https://www.math.wisc.edu/wiki/api.php?action=feedcontributions&user=Spagnolie&feedformat=atomUW-Math Wiki - User contributions [en]2021-01-26T16:34:11ZUser contributionsMediaWiki 1.30.1https://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS/absS21&diff=20643Applied/ACMS/absS212021-01-25T16:34:45Z<p>Spagnolie: /* ACMS Abstracts: Spring 2021 */</p>
<hr />
<div>= ACMS Abstracts: Spring 2021 =<br />
<br />
=== Christina Kurzthaler (Princeton) ===<br />
<br />
Complex Transport Phenomena<br />
<br />
Abstract: Self-propelled agents are intrinsically out of equilibrium and exhibit a variety of unusual transport features. In this talk, I will discuss the spatiotemporal dynamics of catalytic Janus colloids characterized in terms of the intermediate scattering function. Our findings show quantitative agreement of our analytic theory for the active Brownian particle model with experimental observations from the smallest length scales, where translational diffusion and self-propulsion dominate, up to the larges ones, which probe the rotational diffusion of the active agents. In the second part of this talk, I will address the hydrodynamic interactions between sedimenting particles and surfaces with corrugated topographies, omnipresent in biological and microfluidic environments. I will present an analytic theory for the roughness-induced mobility and discuss the sedimentation behavior of a sphere next to periodic and randomly structured surfaces.<br />
<br />
<br />
=== Antoine Remond-Tiedrez (UW) === <br />
<br />
Instability of an Anisotropic Micropolar Fluid<br />
<br />
Abstract: Many aerosols and suspensions, or more broadly fluids containing a non-trivial structure at a microscopic scale, can be described by the theory of micropolar fluids. The resulting equations couple the Navier-Stokes equations which describe the macroscopic motion of the fluid to evolution equations for the angular momentum and the moment of inertia associated with the microcopic structure. In this talk we will discuss the case of viscous incompressible three-dimensional micropolar fluids. We will discuss how, when subject to a fixed torque acting at the microscopic scale, the nonlinear stability of the unique equilibrium of this system depends on the shape of the microstructure.</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS&diff=20642Applied/ACMS2021-01-25T16:33:40Z<p>Spagnolie: /* Spring 2021 */</p>
<hr />
<div>__NOTOC__<br />
<br />
= Applied and Computational Mathematics Seminar =<br />
<br />
*'''When:''' Fridays at 2:25pm (except as otherwise indicated)<br />
*'''Where:''' 901 Van Vleck Hall<br />
*'''Organizers:''' [http://www.math.wisc.edu/~qinli/ Qin Li], [http://www.math.wisc.edu/~spagnolie/ Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''To join the ACMS mailing list:''' Send mail to [mailto:acms+join@g-groups.wisc.edu acms+join@g-groups.wisc.edu].<br />
<br />
<br><br />
<br />
== Spring 2021 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
| Jan 29<br />
|Christina Kurzthaler (Princeton)<br />
|''[[Applied/ACMS/absS21#Christina Kurzthaler (Princeton)|Complex Transport Phenomena]]''<br />
|Jean-Luc<br />
|-<br />
| Feb 5<br />
|[https://www.math.wisc.edu/~remondtiedre/ Antoine Remond-Tiedrez] (UW)<br />
|''[[Applied/ACMS/absS21#Antoine Remond-Tiedrez (UW)|Instability of an Anisotropic Micropolar Fluid]]''<br />
|Spagnolie<br />
|-<br />
| Feb 12<br />
|[http://appliedmaths.sun.ac.za/~htouchette/ Hugo Touchette] (Stellenbosch University)<br />
|''[[Applied/ACMS/absS21#Hugo Touchette (Stellenbosch University)|TBA]]''<br />
|Jean-Luc<br />
|-<br />
| Feb 19<br />
|[https://www.meteo.physik.uni-muenchen.de/~tijana.pfander/ Tijana Pfander] (Ludwig-Maximilians-University of Munich)<br />
|''[[Applied/ACMS/absS21#Tijana Pfander (UW)|TBA]]''<br />
|Chen<br />
|-<br />
| Feb 26<br />
|[https://www.math.wisc.edu/~qdeng37/ Quanling Deng] (UW)<br />
|''[[Applied/ACMS/absS21#Quanling Deng (UW)|TBA]]''<br />
|Stechmann and Chen<br />
|-<br />
| Mar 5<br />
|<br />
|<br />
|<br />
|-<br />
| Mar 12<br />
|[https://www.math.umass.edu/directory/faculty/yulong-lu Yulong Lu] (University of Massachusetts)<br />
|''[[Applied/ACMS/absS21#Yulong Lu (University of Massachusetts)|TBA]]''<br />
|Li<br />
|-<br />
| Mar 19<br />
|Michelle DiBenedetto (University of Washington)<br />
|TBA<br />
|Jean-Luc<br />
|-<br />
| Mar 26<br />
|[https://drexel.edu/coas/faculty-research/faculty-directory/mondaini-cecilia/ Cecilia Mondaini] (Drexel University)<br />
|TBA<br />
|Chen<br />
|-<br />
| Apr 2<br />
|<br />
|<br />
|<br />
|-<br />
| Apr 9<br />
|<br />
|<br />
|<br />
|-<br />
| Apr 16<br />
|<br />
|<br />
|<br />
|-<br />
| Apr 23<br />
|<br />
|<br />
|<br />
|-<br />
|}<br />
<br />
== Future semesters ==<br />
<br />
*[[Applied/ACMS/Spring2021|Fall 2021]]<br />
<br />
<br />
----<br />
<br />
== Archived semesters ==<br />
<br />
*[[Applied/ACMS/Fall2020|Fall 2020]]<br />
*[[Applied/ACMS/Spring2020|Spring 2020]]<br />
*[[Applied/ACMS/Fall2019|Fall 2019]]<br />
*[[Applied/ACMS/Spring2019|Spring 2019]]<br />
*[[Applied/ACMS/Fall2018|Fall 2018]]<br />
*[[Applied/ACMS/Spring2018|Spring 2018]]<br />
*[[Applied/ACMS/Fall2017|Fall 2017]]<br />
*[[Applied/ACMS/Spring2017|Spring 2017]]<br />
*[[Applied/ACMS/Fall2016|Fall 2016]]<br />
*[[Applied/ACMS/Spring2016|Spring 2016]]<br />
*[[Applied/ACMS/Fall2015|Fall 2015]]<br />
*[[Applied/ACMS/Spring2015|Spring 2015]]<br />
*[[Applied/ACMS/Fall2014|Fall 2014]]<br />
*[[Applied/ACMS/Spring2014|Spring 2014]]<br />
*[[Applied/ACMS/Fall2013|Fall 2013]]<br />
*[[Applied/ACMS/Spring2013|Spring 2013]]<br />
*[[Applied/ACMS/Fall2012|Fall 2012]]<br />
*[[Applied/ACMS/Spring2012|Spring 2012]]<br />
*[[Applied/ACMS/Fall2011|Fall 2011]]<br />
*[[Applied/ACMS/Spring2011|Spring 2011]]<br />
*[[Applied/ACMS/Fall2010|Fall 2010]]<br />
<!--<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring10.html Spring 2010]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall09.html Fall 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring09.html Spring 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall08.html Fall 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring08.html Spring 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall07.html Fall 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring07.html Spring 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall06.html Fall 2006]<br />
--><br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/Physical_Applied_Math&diff=20588Applied/Physical Applied Math2021-01-21T15:54:30Z<p>Spagnolie: /* Spring 2021 */</p>
<hr />
<div>= Physical Applied Math Group Meeting =<br />
<br />
*'''When:''' Thursdays at 4:00pm (unless there is a [https://www.math.wisc.edu/deptmeetings Department Meeting])<br />
*'''Where:''' Zoom (contact SES or J-LT for link) <s>901 Van Vleck Hall</s><br />
*'''Organizers:''' [http://www.math.wisc.edu/~spagnolie Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''Announcements:''' Contact SES or J-LT to be added as a guest to our Slack channel.<br />
<br />
== Spring 2021 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
|-<br />
|Jan. 28<br />
|''no group meeting''<br />
|''faculty meeting @ 3:30pm''<br />
|-<br />
|Feb. 4<br />
|Organizational meeting<br />
|<br />
|-<br />
|Feb. 11<br />
|<br />
|<br />
|-<br />
|Feb. 18<br />
|<br />
|<br />
|-<br />
|Feb. 25<br />
|<br />
|<br />
|-<br />
|Mar. 4<br />
|<br />
|<br />
|-<br />
|Mar. 11<br />
|<br />
|<br />
|-<br />
|Mar. 18<br />
|<br />
|<br />
|-<br />
|Mar. 25<br />
|<br />
|<br />
|-<br />
|Apr. 1<br />
|<br />
|<br />
|-<br />
|Apr. 8<br />
|<br />
|<br />
|-<br />
|Apr. 15<br />
|<br />
|<br />
|-<br />
|Apr. 22<br />
|<br />
|<br />
|-<br />
|Apr. 29<br />
|<br />
|<br />
|-<br />
|}<br />
<br />
== Archived semesters ==<br />
*[[Applied/Physical_Applied_Math/Fall2020|Fall 2020]]<br />
*[[Applied/Physical_Applied_Math/Summer2020|Summer 2020]]<br />
*[[Applied/Physical_Applied_Math/Spring2020|Spring 2020]]<br />
*[[Applied/Physical_Applied_Math/Fall2019|Fall 2019]]<br />
*[[Applied/Physical_Applied_Math/Spring2019|Spring 2019]]<br />
*[[Applied/Physical_Applied_Math/Fall2018|Fall 2018]]<br />
*[[Applied/Physical_Applied_Math/Spring2018|Spring 2018]]<br />
*[[Applied/Physical_Applied_Math/Fall2017|Fall 2017]]<br />
*[[Applied/Physical_Applied_Math/Spring2017|Spring 2017]]<br />
*[[Applied/Physical_Applied_Math/Fall2016|Fall 2016]]<br />
*[[Applied/Physical_Applied_Math/Spring2016|Spring 2016]]<br />
*[[Applied/Physical_Applied_Math/Fall2015|Fall 2015]]<br />
*[[Applied/Physical_Applied_Math/Spring2015|Spring 2015]]<br />
*[[Applied/Physical_Applied_Math/Summer2014|Summer 2014]]<br />
*[[Applied/Physical_Applied_Math/Spring2014|Spring 2014]]<br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/Physical_Applied_Math&diff=20587Applied/Physical Applied Math2021-01-21T15:51:23Z<p>Spagnolie: /* Fall 2020 */</p>
<hr />
<div>= Physical Applied Math Group Meeting =<br />
<br />
*'''When:''' Thursdays at 4:00pm (unless there is a [https://www.math.wisc.edu/deptmeetings Department Meeting])<br />
*'''Where:''' Zoom (contact SES or J-LT for link) <s>901 Van Vleck Hall</s><br />
*'''Organizers:''' [http://www.math.wisc.edu/~spagnolie Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''Announcements:''' Contact SES or J-LT to be added as a guest to our Slack channel.<br />
<br />
== Spring 2021 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
|-<br />
|Jan. 28<br />
|Organizational meeting<br />
|<br />
|-<br />
|Feb. 4<br />
|''no group meeting''<br />
|''faculty meeting @ 3:30pm''<br />
|-<br />
|Feb. 11<br />
|<br />
|<br />
|-<br />
|Feb. 18<br />
|<br />
|<br />
|-<br />
|Feb. 25<br />
|<br />
|<br />
|-<br />
|Mar. 4<br />
|<br />
|<br />
|-<br />
|Mar. 11<br />
|<br />
|<br />
|-<br />
|Mar. 18<br />
|<br />
|<br />
|-<br />
|Mar. 25<br />
|<br />
|<br />
|-<br />
|Apr. 1<br />
|<br />
|<br />
|-<br />
|Apr. 8<br />
|<br />
|<br />
|-<br />
|Apr. 15<br />
|<br />
|<br />
|-<br />
|Apr. 22<br />
|<br />
|<br />
|-<br />
|Apr. 29<br />
|<br />
|<br />
|-<br />
|}<br />
<br />
== Archived semesters ==<br />
*[[Applied/Physical_Applied_Math/Fall2020|Fall 2020]]<br />
*[[Applied/Physical_Applied_Math/Summer2020|Summer 2020]]<br />
*[[Applied/Physical_Applied_Math/Spring2020|Spring 2020]]<br />
*[[Applied/Physical_Applied_Math/Fall2019|Fall 2019]]<br />
*[[Applied/Physical_Applied_Math/Spring2019|Spring 2019]]<br />
*[[Applied/Physical_Applied_Math/Fall2018|Fall 2018]]<br />
*[[Applied/Physical_Applied_Math/Spring2018|Spring 2018]]<br />
*[[Applied/Physical_Applied_Math/Fall2017|Fall 2017]]<br />
*[[Applied/Physical_Applied_Math/Spring2017|Spring 2017]]<br />
*[[Applied/Physical_Applied_Math/Fall2016|Fall 2016]]<br />
*[[Applied/Physical_Applied_Math/Spring2016|Spring 2016]]<br />
*[[Applied/Physical_Applied_Math/Fall2015|Fall 2015]]<br />
*[[Applied/Physical_Applied_Math/Spring2015|Spring 2015]]<br />
*[[Applied/Physical_Applied_Math/Summer2014|Summer 2014]]<br />
*[[Applied/Physical_Applied_Math/Spring2014|Spring 2014]]<br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/Physical_Applied_Math/Fall2020&diff=20586Applied/Physical Applied Math/Fall20202021-01-21T15:47:59Z<p>Spagnolie: Created page with "== Fall 2020 == {| cellpadding="8" !align="left" | date !align="left" | speaker !align="left" | title |- |Sept. 3 |Organizational meeting | |- |Sept. 10 |''no group meeting..."</p>
<hr />
<div>== Fall 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
|-<br />
|Sept. 3<br />
|Organizational meeting<br />
|<br />
|-<br />
|Sept. 10<br />
|''no group meeting''<br />
|''faculty meeting @ 3:30pm''<br />
|-<br />
|Sept. 17<br />
|Saverio<br />
|<br />
|-<br />
|Sept. 24<br />
|Wil<br />
|Geometric flows and moving surfaces<br />
|-<br />
|Oct 1<br />
|Bryan<br />
|Homogenization of the advection-diffusion equation in the presence of a source<br />
|-<br />
|Oct 8<br />
|<br />
|''faculty meeting''<br />
|-<br />
|Oct 15<br />
|Chris<br />
|Evolutionary stable strategies and the connection between game theory and the Ising model<br />
|-<br />
|Oct 22<br />
|Yu<br />
|Narrow exit problem with sink flow<br />
|-<br />
|Oct 29<br />
|Hongfei<br />
|Complex model of swimmer interactions<br />
|-<br />
|Nov 5<br />
|Jean-Luc<br />
|Equilibria of Fokker-Planck equations<br />
|-<br />
|Nov 12<br />
|Hongyi Huang<br />
|Bubbles!<br />
|-<br />
|Nov 19<br />
|<br />
|Watch party for ''Gallery of Fluid Motion'' videos<br />
|-<br />
|Nov 26<br />
|<br />
|''Thanksgiving''<br />
|-<br />
|Dec 3<br />
|<br />
|''faculty meeting''<br />
|-<br />
|Dec 10<br />
|Saverio<br />
|Hydrodynamic interaction of swimmer with boundary<br />
|-<br />
|}</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/Physical_Applied_Math&diff=20585Applied/Physical Applied Math2021-01-21T15:47:48Z<p>Spagnolie: /* Archived semesters */</p>
<hr />
<div>= Physical Applied Math Group Meeting =<br />
<br />
*'''When:''' Thursdays at 4:00pm (unless there is a [https://www.math.wisc.edu/deptmeetings Department Meeting])<br />
*'''Where:''' Zoom (contact SES or J-LT for link) <s>901 Van Vleck Hall</s><br />
*'''Organizers:''' [http://www.math.wisc.edu/~spagnolie Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''Announcements:''' Contact SES or J-LT to be added as a guest to our Slack channel.<br />
<br />
== Fall 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
|-<br />
|Sept. 3<br />
|Organizational meeting<br />
|<br />
|-<br />
|Sept. 10<br />
|''no group meeting''<br />
|''faculty meeting @ 3:30pm''<br />
|-<br />
|Sept. 17<br />
|Saverio<br />
|<br />
|-<br />
|Sept. 24<br />
|Wil<br />
|Geometric flows and moving surfaces<br />
|-<br />
|Oct 1<br />
|Bryan<br />
|Homogenization of the advection-diffusion equation in the presence of a source<br />
|-<br />
|Oct 8<br />
|<br />
|''faculty meeting''<br />
|-<br />
|Oct 15<br />
|Chris<br />
|Evolutionary stable strategies and the connection between game theory and the Ising model<br />
|-<br />
|Oct 22<br />
|Yu<br />
|Narrow exit problem with sink flow<br />
|-<br />
|Oct 29<br />
|Hongfei<br />
|Complex model of swimmer interactions<br />
|-<br />
|Nov 5<br />
|Jean-Luc<br />
|Equilibria of Fokker-Planck equations<br />
|-<br />
|Nov 12<br />
|Hongyi Huang<br />
|Bubbles!<br />
|-<br />
|Nov 19<br />
|<br />
|Watch party for ''Gallery of Fluid Motion'' videos<br />
|-<br />
|Nov 26<br />
|<br />
|''Thanksgiving''<br />
|-<br />
|Dec 3<br />
|<br />
|''faculty meeting''<br />
|-<br />
|Dec 10<br />
|Saverio<br />
|Hydrodynamic interaction of swimmer with boundary<br />
|-<br />
|}<br />
<br />
== Archived semesters ==<br />
*[[Applied/Physical_Applied_Math/Fall2020|Fall 2020]]<br />
*[[Applied/Physical_Applied_Math/Summer2020|Summer 2020]]<br />
*[[Applied/Physical_Applied_Math/Spring2020|Spring 2020]]<br />
*[[Applied/Physical_Applied_Math/Fall2019|Fall 2019]]<br />
*[[Applied/Physical_Applied_Math/Spring2019|Spring 2019]]<br />
*[[Applied/Physical_Applied_Math/Fall2018|Fall 2018]]<br />
*[[Applied/Physical_Applied_Math/Spring2018|Spring 2018]]<br />
*[[Applied/Physical_Applied_Math/Fall2017|Fall 2017]]<br />
*[[Applied/Physical_Applied_Math/Spring2017|Spring 2017]]<br />
*[[Applied/Physical_Applied_Math/Fall2016|Fall 2016]]<br />
*[[Applied/Physical_Applied_Math/Spring2016|Spring 2016]]<br />
*[[Applied/Physical_Applied_Math/Fall2015|Fall 2015]]<br />
*[[Applied/Physical_Applied_Math/Spring2015|Spring 2015]]<br />
*[[Applied/Physical_Applied_Math/Summer2014|Summer 2014]]<br />
*[[Applied/Physical_Applied_Math/Spring2014|Spring 2014]]<br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS&diff=20348Applied/ACMS2020-11-14T16:09:59Z<p>Spagnolie: /* Fall 2020 */</p>
<hr />
<div>__NOTOC__<br />
<br />
= Applied and Computational Mathematics Seminar =<br />
<br />
*'''When:''' Fridays at 2:25pm (except as otherwise indicated)<br />
*'''Where:''' 901 Van Vleck Hall<br />
*'''Organizers:''' [http://www.math.wisc.edu/~qinli/ Qin Li], [http://www.math.wisc.edu/~spagnolie/ Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''To join the ACMS mailing list:''' Send mail to [mailto:acms+join@g-groups.wisc.edu acms+join@g-groups.wisc.edu].<br />
<br />
<br><br />
<br />
<br />
== Fall 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
| Sep 11<br />
|[https://cee.stanford.edu/people/nicholas-ouellette Nick Ouellette (Stanford)]<br />
|''[[Applied/ACMS/absF20#Nick Ouellette (Stanford)|Tensor Geometry in the Turbulent Cascade]]''<br />
|Jean-Luc<br />
|-<br />
| Sep 18<br />
|[https://www.researchgate.net/profile/Harry_Lee24 Harry Lee (UW-Madison and UMich)]<br />
|''[[Applied/ACMS/absF20#Harry Lee (UW-Madison, UMich)|Recent extension of V.I. Arnold's and J.L. Synge's mathematical theory of shear flows]]''<br />
|Wally<br />
|-<br />
| Sep 25<br />
|[https://www.mtholyoke.edu/people/spencer-smith Spencer Smith (Mount Holyoke)]<br />
|''[[Applied/ACMS/absF20#Spencer Smith (Mount Holyoke)|Braids on a lattice and maximally efficient mixing in active matter systems]]''<br />
|Jean-Luc<br />
|-<br />
| Oct 2<br />
|[https://zhizhenz.ece.illinois.edu/ Zhizhen Jane Zhao] (UIUC)<br />
|''[[Applied/ACMS/absF20#Zhizhen Jane Zhao (UIUC)|Exploiting Group and Geometric Structures for Massive Data Analysis]]''<br />
| Li & Chen<br />
|<br />
|<br />
|-<br />
| Oct 9<br />
|[https://igppweb.ucsd.edu/~mmorzfeld/ Matthias Morzfeld] (Scripps & UCSD)<br />
|''[[Applied/ACMS/absF20#Matthias Morzfeld (Scripps & UCSD)|What is Bayesian inference, why is it useful in Earth science and why is it challenging to do numerically?]]''<br />
| Chen<br />
|<br />
|<br />
|-<br />
| Oct 16<br />
|[https://jingweihu-math.github.io/webpage/ Jingwei Hu] (Purdue)<br />
|''[[Applied/ACMS/absF20#Jingwei Hu (Purdue)|A new stability and convergence proof of the Fourier-Galerkin spectral method for the spatially homogeneous Boltzmann equation]]''<br />
| Li<br />
|<br />
|-<br />
| Oct 23<br />
|[https://www.aos.wisc.edu/~dvimont/Home.html Dan Vimont] (UW-Madison, AOS)<br />
|''[[Applied/ACMS/absF20#Dan Vimont (UW-Madison, AOS)|Advances in Linear Inverse Modeling for Understanding Tropical Pacific Climate Variability]]''<br />
| Stechmann<br />
|<br />
|-<br />
| Oct 30<br />
|[http://www.dam.brown.edu/people/spsmith/ Sam Punshon-Smith] (Brown)<br />
|''[[Applied/ACMS/absF20#Sam Punshon-Smith (Brown)|Scalar mixing and the Batchelor spectrum in stochastic fluid mechanics]]''<br />
| Li<br />
|<br />
|-<br />
| Nov 6<br />
|[https://www.math.uci.edu/people/yimin-zhong Yimin Zhong] (UCI, Duke)<br />
|''[[Applied/ACMS/absF20#Yimin Zhong (UCI and Duke)|Quantitative PhotoAcoustic Tomography (PAT) with simplified PN approximation]]''<br />
|Li<br />
|<br />
|-<br />
| Nov 13<br />
|'''1:30pm''' [https://www.cmu.edu/biolphys/deserno/ Markus Deserno] (Carnegie Mellon)<br />
|''[[Applied/ACMS/absF20#Markus Deserno (Carnegie Mellon)|Spontaneous curvature, differential stress, and bending modulus of asymmetric lipid membranes]]''<br />
(Virtual, link to recording [https://www.math.wisc.edu/~appliedmathlab/Seminars/ACMS_111320_Deserno.mp4 here])<br />
|Spagnolie<br />
|-<br />
| Nov 20<br />
|[https://www.usna.edu/Users/math/lunasin/index.php/ Evelyn Lunasin] (USNA)<br />
|''[[Applied/ACMS/absF20#Evelyn Lunasin (USNA)|Finite Number of Determining Parameters for the 1D Kuramoto-Sivashinsky equation with Applications to Feedback Control and Data Assimilations]]''<br />
|Jean-Luc & Chen<br />
|-<br />
| Nov 27<br />
|''Thangksgiving recess''<br />
|<br />
|<br />
|-<br />
| Dec 4<br />
||[https://www.math.arizona.edu/people/chertkov Michael Chertkov] (U. Arizona)<br />
|''[[Applied/ACMS/absF20#Michael Chertkov (U Arizona)|TBD]]''<br />
|Zepeda-Nunez<br />
|<br />
|<br />
|-<br />
|}<br />
<br />
== Future semesters ==<br />
<br />
*[[Applied/ACMS/Spring2021|Spring 2021]]<br />
<br />
<br />
----<br />
<br />
== Archived semesters ==<br />
<br />
*[[Applied/ACMS/Spring2020|Spring 2020]]<br />
*[[Applied/ACMS/Fall2019|Fall 2019]]<br />
*[[Applied/ACMS/Spring2019|Spring 2019]]<br />
*[[Applied/ACMS/Fall2018|Fall 2018]]<br />
*[[Applied/ACMS/Spring2018|Spring 2018]]<br />
*[[Applied/ACMS/Fall2017|Fall 2017]]<br />
*[[Applied/ACMS/Spring2017|Spring 2017]]<br />
*[[Applied/ACMS/Fall2016|Fall 2016]]<br />
*[[Applied/ACMS/Spring2016|Spring 2016]]<br />
*[[Applied/ACMS/Fall2015|Fall 2015]]<br />
*[[Applied/ACMS/Spring2015|Spring 2015]]<br />
*[[Applied/ACMS/Fall2014|Fall 2014]]<br />
*[[Applied/ACMS/Spring2014|Spring 2014]]<br />
*[[Applied/ACMS/Fall2013|Fall 2013]]<br />
*[[Applied/ACMS/Spring2013|Spring 2013]]<br />
*[[Applied/ACMS/Fall2012|Fall 2012]]<br />
*[[Applied/ACMS/Spring2012|Spring 2012]]<br />
*[[Applied/ACMS/Fall2011|Fall 2011]]<br />
*[[Applied/ACMS/Spring2011|Spring 2011]]<br />
*[[Applied/ACMS/Fall2010|Fall 2010]]<br />
<!--<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring10.html Spring 2010]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall09.html Fall 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring09.html Spring 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall08.html Fall 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring08.html Spring 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall07.html Fall 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring07.html Spring 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall06.html Fall 2006]<br />
--><br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS&diff=20345Applied/ACMS2020-11-14T04:54:54Z<p>Spagnolie: /* Fall 2020 */</p>
<hr />
<div>__NOTOC__<br />
<br />
= Applied and Computational Mathematics Seminar =<br />
<br />
*'''When:''' Fridays at 2:25pm (except as otherwise indicated)<br />
*'''Where:''' 901 Van Vleck Hall<br />
*'''Organizers:''' [http://www.math.wisc.edu/~qinli/ Qin Li], [http://www.math.wisc.edu/~spagnolie/ Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''To join the ACMS mailing list:''' Send mail to [mailto:acms+join@g-groups.wisc.edu acms+join@g-groups.wisc.edu].<br />
<br />
<br><br />
<br />
<br />
== Fall 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
| Sep 11<br />
|[https://cee.stanford.edu/people/nicholas-ouellette Nick Ouellette (Stanford)]<br />
|''[[Applied/ACMS/absF20#Nick Ouellette (Stanford)|Tensor Geometry in the Turbulent Cascade]]''<br />
|Jean-Luc<br />
|-<br />
| Sep 18<br />
|[https://www.researchgate.net/profile/Harry_Lee24 Harry Lee (UW-Madison and UMich)]<br />
|''[[Applied/ACMS/absF20#Harry Lee (UW-Madison, UMich)|Recent extension of V.I. Arnold's and J.L. Synge's mathematical theory of shear flows]]''<br />
|Wally<br />
|-<br />
| Sep 25<br />
|[https://www.mtholyoke.edu/people/spencer-smith Spencer Smith (Mount Holyoke)]<br />
|''[[Applied/ACMS/absF20#Spencer Smith (Mount Holyoke)|Braids on a lattice and maximally efficient mixing in active matter systems]]''<br />
|Jean-Luc<br />
|-<br />
| Oct 2<br />
|[https://zhizhenz.ece.illinois.edu/ Zhizhen Jane Zhao] (UIUC)<br />
|''[[Applied/ACMS/absF20#Zhizhen Jane Zhao (UIUC)|Exploiting Group and Geometric Structures for Massive Data Analysis]]''<br />
| Li & Chen<br />
|<br />
|<br />
|-<br />
| Oct 9<br />
|[https://igppweb.ucsd.edu/~mmorzfeld/ Matthias Morzfeld] (Scripps & UCSD)<br />
|''[[Applied/ACMS/absF20#Matthias Morzfeld (Scripps & UCSD)|What is Bayesian inference, why is it useful in Earth science and why is it challenging to do numerically?]]''<br />
| Chen<br />
|<br />
|<br />
|-<br />
| Oct 16<br />
|[https://jingweihu-math.github.io/webpage/ Jingwei Hu] (Purdue)<br />
|''[[Applied/ACMS/absF20#Jingwei Hu (Purdue)|A new stability and convergence proof of the Fourier-Galerkin spectral method for the spatially homogeneous Boltzmann equation]]''<br />
| Li<br />
|<br />
|-<br />
| Oct 23<br />
|[https://www.aos.wisc.edu/~dvimont/Home.html Dan Vimont] (UW-Madison, AOS)<br />
|''[[Applied/ACMS/absF20#Dan Vimont (UW-Madison, AOS)|Advances in Linear Inverse Modeling for Understanding Tropical Pacific Climate Variability]]''<br />
| Stechmann<br />
|<br />
|-<br />
| Oct 30<br />
|[http://www.dam.brown.edu/people/spsmith/ Sam Punshon-Smith] (Brown)<br />
|''[[Applied/ACMS/absF20#Sam Punshon-Smith (Brown)|Scalar mixing and the Batchelor spectrum in stochastic fluid mechanics]]''<br />
| Li<br />
|<br />
|-<br />
| Nov 6<br />
|[https://www.math.uci.edu/people/yimin-zhong Yimin Zhong] (UCI, Duke)<br />
|''[[Applied/ACMS/absF20#Yimin Zhong (UCI and Duke)|Quantitative PhotoAcoustic Tomography (PAT) with simplified PN approximation]]''<br />
|Li<br />
|<br />
|-<br />
| Nov 13<br />
|'''1:30pm''' [https://www.cmu.edu/biolphys/deserno/ Markus Deserno] (Carnegie Mellon)<br />
|''[[Applied/ACMS/absF20#Markus Deserno (Carnegie Mellon)|Spontaneous curvature, differential stress, and bending modulus of asymmetric lipid membranes]]''<br />
|(Virtual, link to recording [https://www.math.wisc.edu/~appliedmathlab/Seminars/ACMS_111320_Deserno.mp4 here])<br />
|Spagnolie<br />
|-<br />
| Nov 20<br />
|[https://www.usna.edu/Users/math/lunasin/index.php/ Evelyn Lunasin] (USNA)<br />
|''[[Applied/ACMS/absF20#Evelyn Lunasin (USNA)|Finite Number of Determining Parameters for the 1D Kuramoto-Sivashinsky equation with Applications to Feedback Control and Data Assimilations]]''<br />
|Jean-Luc & Chen<br />
|-<br />
| Nov 27<br />
|''Thangksgiving recess''<br />
|<br />
|<br />
|-<br />
| Dec 4<br />
||[https://www.math.arizona.edu/people/chertkov Michael Chertkov] (U. Arizona)<br />
|''[[Applied/ACMS/absF20#Michael Chertkov (U Arizona)|TBD]]''<br />
|Zepeda-Nunez<br />
|<br />
|<br />
|-<br />
|}<br />
<br />
== Future semesters ==<br />
<br />
*[[Applied/ACMS/Spring2021|Spring 2021]]<br />
<br />
<br />
----<br />
<br />
== Archived semesters ==<br />
<br />
*[[Applied/ACMS/Spring2020|Spring 2020]]<br />
*[[Applied/ACMS/Fall2019|Fall 2019]]<br />
*[[Applied/ACMS/Spring2019|Spring 2019]]<br />
*[[Applied/ACMS/Fall2018|Fall 2018]]<br />
*[[Applied/ACMS/Spring2018|Spring 2018]]<br />
*[[Applied/ACMS/Fall2017|Fall 2017]]<br />
*[[Applied/ACMS/Spring2017|Spring 2017]]<br />
*[[Applied/ACMS/Fall2016|Fall 2016]]<br />
*[[Applied/ACMS/Spring2016|Spring 2016]]<br />
*[[Applied/ACMS/Fall2015|Fall 2015]]<br />
*[[Applied/ACMS/Spring2015|Spring 2015]]<br />
*[[Applied/ACMS/Fall2014|Fall 2014]]<br />
*[[Applied/ACMS/Spring2014|Spring 2014]]<br />
*[[Applied/ACMS/Fall2013|Fall 2013]]<br />
*[[Applied/ACMS/Spring2013|Spring 2013]]<br />
*[[Applied/ACMS/Fall2012|Fall 2012]]<br />
*[[Applied/ACMS/Spring2012|Spring 2012]]<br />
*[[Applied/ACMS/Fall2011|Fall 2011]]<br />
*[[Applied/ACMS/Spring2011|Spring 2011]]<br />
*[[Applied/ACMS/Fall2010|Fall 2010]]<br />
<!--<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring10.html Spring 2010]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall09.html Fall 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring09.html Spring 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall08.html Fall 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring08.html Spring 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall07.html Fall 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring07.html Spring 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall06.html Fall 2006]<br />
--><br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS&diff=20314Applied/ACMS2020-11-09T23:32:46Z<p>Spagnolie: /* Fall 2020 */</p>
<hr />
<div>__NOTOC__<br />
<br />
= Applied and Computational Mathematics Seminar =<br />
<br />
*'''When:''' Fridays at 2:25pm (except as otherwise indicated)<br />
*'''Where:''' 901 Van Vleck Hall<br />
*'''Organizers:''' [http://www.math.wisc.edu/~qinli/ Qin Li], [http://www.math.wisc.edu/~spagnolie/ Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''To join the ACMS mailing list:''' Send mail to [mailto:acms+join@g-groups.wisc.edu acms+join@g-groups.wisc.edu].<br />
<br />
<br><br />
<br />
<br />
== Fall 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
| Sep 11<br />
|[https://cee.stanford.edu/people/nicholas-ouellette Nick Ouellette (Stanford)]<br />
|''[[Applied/ACMS/absF20#Nick Ouellette (Stanford)|Tensor Geometry in the Turbulent Cascade]]''<br />
|Jean-Luc<br />
|-<br />
| Sep 18<br />
|[https://www.researchgate.net/profile/Harry_Lee24 Harry Lee (UW-Madison and UMich)]<br />
|''[[Applied/ACMS/absF20#Harry Lee (UW-Madison, UMich)|Recent extension of V.I. Arnold's and J.L. Synge's mathematical theory of shear flows]]''<br />
|Wally<br />
|-<br />
| Sep 25<br />
|[https://www.mtholyoke.edu/people/spencer-smith Spencer Smith (Mount Holyoke)]<br />
|''[[Applied/ACMS/absF20#Spencer Smith (Mount Holyoke)|Braids on a lattice and maximally efficient mixing in active matter systems]]''<br />
|Jean-Luc<br />
|-<br />
| Oct 2<br />
|[https://zhizhenz.ece.illinois.edu/ Zhizhen Jane Zhao] (UIUC)<br />
|''[[Applied/ACMS/absF20#Zhizhen Jane Zhao (UIUC)|Exploiting Group and Geometric Structures for Massive Data Analysis]]''<br />
| Li & Chen<br />
|<br />
|<br />
|-<br />
| Oct 9<br />
|[https://igppweb.ucsd.edu/~mmorzfeld/ Matthias Morzfeld] (Scripps & UCSD)<br />
|''[[Applied/ACMS/absF20#Matthias Morzfeld (Scripps & UCSD)|What is Bayesian inference, why is it useful in Earth science and why is it challenging to do numerically?]]''<br />
| Chen<br />
|<br />
|<br />
|-<br />
| Oct 16<br />
|[https://jingweihu-math.github.io/webpage/ Jingwei Hu] (Purdue)<br />
|''[[Applied/ACMS/absF20#Jingwei Hu (Purdue)|A new stability and convergence proof of the Fourier-Galerkin spectral method for the spatially homogeneous Boltzmann equation]]''<br />
| Li<br />
|<br />
|-<br />
| Oct 23<br />
|[https://www.aos.wisc.edu/~dvimont/Home.html Dan Vimont] (UW-Madison, AOS)<br />
|''[[Applied/ACMS/absF20#Dan Vimont (UW-Madison, AOS)|Advances in Linear Inverse Modeling for Understanding Tropical Pacific Climate Variability]]''<br />
| Stechmann<br />
|<br />
|-<br />
| Oct 30<br />
|[http://www.dam.brown.edu/people/spsmith/ Sam Punshon-Smith] (Brown)<br />
|''[[Applied/ACMS/absF20#Sam Punshon-Smith (Brown)|Scalar mixing and the Batchelor spectrum in stochastic fluid mechanics]]''<br />
| Li<br />
|<br />
|-<br />
| Nov 6<br />
|[https://www.math.uci.edu/people/yimin-zhong Yimin Zhong] (UCI, Duke)<br />
|''[[Applied/ACMS/absF20#Yimin Zhong (UCI and Duke)|Quantitative PhotoAcoustic Tomography (PAT) with simplified PN approximation]]''<br />
|Li<br />
|<br />
|-<br />
| Nov 13<br />
|'''1:30pm''' [https://www.cmu.edu/biolphys/deserno/ Markus Deserno] (Carnegie Mellon)<br />
|''[[Applied/ACMS/absF20#Markus Deserno (Carnegie Mellon)|Spontaneous curvature, differential stress, and bending modulus of asymmetric lipid membranes]]''<br />
|Spagnolie<br />
|-<br />
| Nov 20<br />
|[https://www.usna.edu/Users/math/lunasin/index.php/ Evelyn Lunasin] (USNA)<br />
|''[[Applied/ACMS/absF20#Evelyn Lunasin (USNA)|TBD]]''<br />
|Jean-Luc & Chen<br />
|-<br />
| Nov 27<br />
|''Thangksgiving recess''<br />
|<br />
|<br />
|-<br />
| Dec 4<br />
||[https://www.math.arizona.edu/people/chertkov Michael Chertkov] (U. Arizona)<br />
|''[[Applied/ACMS/absF20#Michael Chertkov (U Arizona)|TBD]]''<br />
|Zepeda-Nunez<br />
|<br />
|<br />
|-<br />
|}<br />
<br />
== Future semesters ==<br />
<br />
*[[Applied/ACMS/Spring2021|Spring 2021]]<br />
<br />
<br />
----<br />
<br />
== Archived semesters ==<br />
<br />
*[[Applied/ACMS/Spring2020|Spring 2020]]<br />
*[[Applied/ACMS/Fall2019|Fall 2019]]<br />
*[[Applied/ACMS/Spring2019|Spring 2019]]<br />
*[[Applied/ACMS/Fall2018|Fall 2018]]<br />
*[[Applied/ACMS/Spring2018|Spring 2018]]<br />
*[[Applied/ACMS/Fall2017|Fall 2017]]<br />
*[[Applied/ACMS/Spring2017|Spring 2017]]<br />
*[[Applied/ACMS/Fall2016|Fall 2016]]<br />
*[[Applied/ACMS/Spring2016|Spring 2016]]<br />
*[[Applied/ACMS/Fall2015|Fall 2015]]<br />
*[[Applied/ACMS/Spring2015|Spring 2015]]<br />
*[[Applied/ACMS/Fall2014|Fall 2014]]<br />
*[[Applied/ACMS/Spring2014|Spring 2014]]<br />
*[[Applied/ACMS/Fall2013|Fall 2013]]<br />
*[[Applied/ACMS/Spring2013|Spring 2013]]<br />
*[[Applied/ACMS/Fall2012|Fall 2012]]<br />
*[[Applied/ACMS/Spring2012|Spring 2012]]<br />
*[[Applied/ACMS/Fall2011|Fall 2011]]<br />
*[[Applied/ACMS/Spring2011|Spring 2011]]<br />
*[[Applied/ACMS/Fall2010|Fall 2010]]<br />
<!--<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring10.html Spring 2010]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall09.html Fall 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring09.html Spring 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall08.html Fall 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring08.html Spring 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall07.html Fall 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring07.html Spring 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall06.html Fall 2006]<br />
--><br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS&diff=20313Applied/ACMS2020-11-09T23:32:35Z<p>Spagnolie: /* Fall 2020 */</p>
<hr />
<div>__NOTOC__<br />
<br />
= Applied and Computational Mathematics Seminar =<br />
<br />
*'''When:''' Fridays at 2:25pm (except as otherwise indicated)<br />
*'''Where:''' 901 Van Vleck Hall<br />
*'''Organizers:''' [http://www.math.wisc.edu/~qinli/ Qin Li], [http://www.math.wisc.edu/~spagnolie/ Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''To join the ACMS mailing list:''' Send mail to [mailto:acms+join@g-groups.wisc.edu acms+join@g-groups.wisc.edu].<br />
<br />
<br><br />
<br />
<br />
== Fall 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
| Sep 11<br />
|[https://cee.stanford.edu/people/nicholas-ouellette Nick Ouellette (Stanford)]<br />
|''[[Applied/ACMS/absF20#Nick Ouellette (Stanford)|Tensor Geometry in the Turbulent Cascade]]''<br />
|Jean-Luc<br />
|-<br />
| Sep 18<br />
|[https://www.researchgate.net/profile/Harry_Lee24 Harry Lee (UW-Madison and UMich)]<br />
|''[[Applied/ACMS/absF20#Harry Lee (UW-Madison, UMich)|Recent extension of V.I. Arnold's and J.L. Synge's mathematical theory of shear flows]]''<br />
|Wally<br />
|-<br />
| Sep 25<br />
|[https://www.mtholyoke.edu/people/spencer-smith Spencer Smith (Mount Holyoke)]<br />
|''[[Applied/ACMS/absF20#Spencer Smith (Mount Holyoke)|Braids on a lattice and maximally efficient mixing in active matter systems]]''<br />
|Jean-Luc<br />
|-<br />
| Oct 2<br />
|[https://zhizhenz.ece.illinois.edu/ Zhizhen Jane Zhao] (UIUC)<br />
|''[[Applied/ACMS/absF20#Zhizhen Jane Zhao (UIUC)|Exploiting Group and Geometric Structures for Massive Data Analysis]]''<br />
| Li & Chen<br />
|<br />
|<br />
|-<br />
| Oct 9<br />
|[https://igppweb.ucsd.edu/~mmorzfeld/ Matthias Morzfeld] (Scripps & UCSD)<br />
|''[[Applied/ACMS/absF20#Matthias Morzfeld (Scripps & UCSD)|What is Bayesian inference, why is it useful in Earth science and why is it challenging to do numerically?]]''<br />
| Chen<br />
|<br />
|<br />
|-<br />
| Oct 16<br />
|[https://jingweihu-math.github.io/webpage/ Jingwei Hu] (Purdue)<br />
|''[[Applied/ACMS/absF20#Jingwei Hu (Purdue)|A new stability and convergence proof of the Fourier-Galerkin spectral method for the spatially homogeneous Boltzmann equation]]''<br />
| Li<br />
|<br />
|-<br />
| Oct 23<br />
|[https://www.aos.wisc.edu/~dvimont/Home.html Dan Vimont] (UW-Madison, AOS)<br />
|''[[Applied/ACMS/absF20#Dan Vimont (UW-Madison, AOS)|Advances in Linear Inverse Modeling for Understanding Tropical Pacific Climate Variability]]''<br />
| Stechmann<br />
|<br />
|-<br />
| Oct 30<br />
|[http://www.dam.brown.edu/people/spsmith/ Sam Punshon-Smith] (Brown)<br />
|''[[Applied/ACMS/absF20#Sam Punshon-Smith (Brown)|Scalar mixing and the Batchelor spectrum in stochastic fluid mechanics]]''<br />
| Li<br />
|<br />
|-<br />
| Nov 6<br />
|[https://www.math.uci.edu/people/yimin-zhong Yimin Zhong] (UCI, Duke)<br />
|''[[Applied/ACMS/absF20#Yimin Zhong (UCI and Duke)|Quantitative PhotoAcoustic Tomography (PAT) with simplified PN approximation]]''<br />
|Li<br />
|<br />
|-<br />
| Nov 13<br />
|''1:30pm'' [https://www.cmu.edu/biolphys/deserno/ Markus Deserno] (Carnegie Mellon)<br />
|''[[Applied/ACMS/absF20#Markus Deserno (Carnegie Mellon)|Spontaneous curvature, differential stress, and bending modulus of asymmetric lipid membranes]]''<br />
|Spagnolie<br />
|-<br />
| Nov 20<br />
|[https://www.usna.edu/Users/math/lunasin/index.php/ Evelyn Lunasin] (USNA)<br />
|''[[Applied/ACMS/absF20#Evelyn Lunasin (USNA)|TBD]]''<br />
|Jean-Luc & Chen<br />
|-<br />
| Nov 27<br />
|''Thangksgiving recess''<br />
|<br />
|<br />
|-<br />
| Dec 4<br />
||[https://www.math.arizona.edu/people/chertkov Michael Chertkov] (U. Arizona)<br />
|''[[Applied/ACMS/absF20#Michael Chertkov (U Arizona)|TBD]]''<br />
|Zepeda-Nunez<br />
|<br />
|<br />
|-<br />
|}<br />
<br />
== Future semesters ==<br />
<br />
*[[Applied/ACMS/Spring2021|Spring 2021]]<br />
<br />
<br />
----<br />
<br />
== Archived semesters ==<br />
<br />
*[[Applied/ACMS/Spring2020|Spring 2020]]<br />
*[[Applied/ACMS/Fall2019|Fall 2019]]<br />
*[[Applied/ACMS/Spring2019|Spring 2019]]<br />
*[[Applied/ACMS/Fall2018|Fall 2018]]<br />
*[[Applied/ACMS/Spring2018|Spring 2018]]<br />
*[[Applied/ACMS/Fall2017|Fall 2017]]<br />
*[[Applied/ACMS/Spring2017|Spring 2017]]<br />
*[[Applied/ACMS/Fall2016|Fall 2016]]<br />
*[[Applied/ACMS/Spring2016|Spring 2016]]<br />
*[[Applied/ACMS/Fall2015|Fall 2015]]<br />
*[[Applied/ACMS/Spring2015|Spring 2015]]<br />
*[[Applied/ACMS/Fall2014|Fall 2014]]<br />
*[[Applied/ACMS/Spring2014|Spring 2014]]<br />
*[[Applied/ACMS/Fall2013|Fall 2013]]<br />
*[[Applied/ACMS/Spring2013|Spring 2013]]<br />
*[[Applied/ACMS/Fall2012|Fall 2012]]<br />
*[[Applied/ACMS/Spring2012|Spring 2012]]<br />
*[[Applied/ACMS/Fall2011|Fall 2011]]<br />
*[[Applied/ACMS/Spring2011|Spring 2011]]<br />
*[[Applied/ACMS/Fall2010|Fall 2010]]<br />
<!--<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring10.html Spring 2010]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall09.html Fall 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring09.html Spring 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall08.html Fall 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring08.html Spring 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall07.html Fall 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring07.html Spring 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall06.html Fall 2006]<br />
--><br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/Physical_Applied_Math&diff=20310Applied/Physical Applied Math2020-11-09T14:44:38Z<p>Spagnolie: /* Fall 2020 */</p>
<hr />
<div>= Physical Applied Math Group Meeting =<br />
<br />
*'''When:''' Thursdays at 4:00pm (unless there is a [https://www.math.wisc.edu/deptmeetings Department Meeting])<br />
*'''Where:''' Zoom (contact SES or J-LT for link) <s>901 Van Vleck Hall</s><br />
*'''Organizers:''' [http://www.math.wisc.edu/~spagnolie Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''Announcements:''' Contact SES or J-LT to be added as a guest to our Slack channel.<br />
<br />
== Fall 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
|-<br />
|Sept. 3<br />
|Organizational meeting<br />
|<br />
|-<br />
|Sept. 10<br />
|''no group meeting''<br />
|''faculty meeting @ 3:30pm''<br />
|-<br />
|Sept. 17<br />
|Saverio<br />
|<br />
|-<br />
|Sept. 24<br />
|Wil<br />
|Geometric flows and moving surfaces<br />
|-<br />
|Oct 1<br />
|Bryan<br />
|Homogenization of the advection-diffusion equation in the presence of a source<br />
|-<br />
|Oct 8<br />
|<br />
|''faculty meeting''<br />
|-<br />
|Oct 15<br />
|Chris<br />
|Evolutionary stable strategies and the connection between game theory and the Ising model<br />
|-<br />
|Oct 22<br />
|Yu<br />
|Narrow exit problem with sink flow<br />
|-<br />
|Oct 29<br />
|Hongfei<br />
|Complex model of swimmer interactions<br />
|-<br />
|Nov 5<br />
|Jean-Luc<br />
|Equilibria of Fokker-Planck equations<br />
|-<br />
|Nov 12<br />
|Hongyi Huang<br />
|Bubbles!<br />
|-<br />
|Nov 19<br />
|<br />
|<br />
|-<br />
|Nov 26<br />
|<br />
|''Thanksgiving''<br />
|-<br />
|Dec 3<br />
|<br />
|''faculty meeting''<br />
|-<br />
|}<br />
<br />
== Archived semesters ==<br />
*[[Applied/Physical_Applied_Math/Summer2020|Summer 2020]]<br />
*[[Applied/Physical_Applied_Math/Spring2020|Spring 2020]]<br />
*[[Applied/Physical_Applied_Math/Fall2019|Fall 2019]]<br />
*[[Applied/Physical_Applied_Math/Spring2019|Spring 2019]]<br />
*[[Applied/Physical_Applied_Math/Fall2018|Fall 2018]]<br />
*[[Applied/Physical_Applied_Math/Spring2018|Spring 2018]]<br />
*[[Applied/Physical_Applied_Math/Fall2017|Fall 2017]]<br />
*[[Applied/Physical_Applied_Math/Spring2017|Spring 2017]]<br />
*[[Applied/Physical_Applied_Math/Fall2016|Fall 2016]]<br />
*[[Applied/Physical_Applied_Math/Spring2016|Spring 2016]]<br />
*[[Applied/Physical_Applied_Math/Fall2015|Fall 2015]]<br />
*[[Applied/Physical_Applied_Math/Spring2015|Spring 2015]]<br />
*[[Applied/Physical_Applied_Math/Summer2014|Summer 2014]]<br />
*[[Applied/Physical_Applied_Math/Spring2014|Spring 2014]]<br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS&diff=20306Applied/ACMS2020-11-08T20:17:55Z<p>Spagnolie: /* Fall 2020 */</p>
<hr />
<div>__NOTOC__<br />
<br />
= Applied and Computational Mathematics Seminar =<br />
<br />
*'''When:''' Fridays at 2:25pm (except as otherwise indicated)<br />
*'''Where:''' 901 Van Vleck Hall<br />
*'''Organizers:''' [http://www.math.wisc.edu/~qinli/ Qin Li], [http://www.math.wisc.edu/~spagnolie/ Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''To join the ACMS mailing list:''' Send mail to [mailto:acms+join@g-groups.wisc.edu acms+join@g-groups.wisc.edu].<br />
<br />
<br><br />
<br />
<br />
== Fall 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
| Sep 11<br />
|[https://cee.stanford.edu/people/nicholas-ouellette Nick Ouellette (Stanford)]<br />
|''[[Applied/ACMS/absF20#Nick Ouellette (Stanford)|Tensor Geometry in the Turbulent Cascade]]''<br />
|Jean-Luc<br />
|-<br />
| Sep 18<br />
|[https://www.researchgate.net/profile/Harry_Lee24 Harry Lee (UW-Madison and UMich)]<br />
|''[[Applied/ACMS/absF20#Harry Lee (UW-Madison, UMich)|Recent extension of V.I. Arnold's and J.L. Synge's mathematical theory of shear flows]]''<br />
|Wally<br />
|-<br />
| Sep 25<br />
|[https://www.mtholyoke.edu/people/spencer-smith Spencer Smith (Mount Holyoke)]<br />
|''[[Applied/ACMS/absF20#Spencer Smith (Mount Holyoke)|Braids on a lattice and maximally efficient mixing in active matter systems]]''<br />
|Jean-Luc<br />
|-<br />
| Oct 2<br />
|[https://zhizhenz.ece.illinois.edu/ Zhizhen Jane Zhao] (UIUC)<br />
|''[[Applied/ACMS/absF20#Zhizhen Jane Zhao (UIUC)|Exploiting Group and Geometric Structures for Massive Data Analysis]]''<br />
| Li & Chen<br />
|<br />
|<br />
|-<br />
| Oct 9<br />
|[https://igppweb.ucsd.edu/~mmorzfeld/ Matthias Morzfeld] (Scripps & UCSD)<br />
|''[[Applied/ACMS/absF20#Matthias Morzfeld (Scripps & UCSD)|What is Bayesian inference, why is it useful in Earth science and why is it challenging to do numerically?]]''<br />
| Chen<br />
|<br />
|<br />
|-<br />
| Oct 16<br />
|[https://jingweihu-math.github.io/webpage/ Jingwei Hu] (Purdue)<br />
|''[[Applied/ACMS/absF20#Jingwei Hu (Purdue)|A new stability and convergence proof of the Fourier-Galerkin spectral method for the spatially homogeneous Boltzmann equation]]''<br />
| Li<br />
|<br />
|-<br />
| Oct 23<br />
|[https://www.aos.wisc.edu/~dvimont/Home.html Dan Vimont] (UW-Madison, AOS)<br />
|''[[Applied/ACMS/absF20#Dan Vimont (UW-Madison, AOS)|Advances in Linear Inverse Modeling for Understanding Tropical Pacific Climate Variability]]''<br />
| Stechmann<br />
|<br />
|-<br />
| Oct 30<br />
|[http://www.dam.brown.edu/people/spsmith/ Sam Punshon-Smith] (Brown)<br />
|''[[Applied/ACMS/absF20#Sam Punshon-Smith (Brown)|Scalar mixing and the Batchelor spectrum in stochastic fluid mechanics]]''<br />
| Li<br />
|<br />
|-<br />
| Nov 6<br />
|[https://www.math.uci.edu/people/yimin-zhong Yimin Zhong] (UCI, Duke)<br />
|''[[Applied/ACMS/absF20#Yimin Zhong (UCI and Duke)|Quantitative PhotoAcoustic Tomography (PAT) with simplified PN approximation]]''<br />
|Li<br />
|<br />
|-<br />
| Nov 13<br />
|[https://www.cmu.edu/biolphys/deserno/ Markus Deserno] (Carnegie Mellon)<br />
|''[[Applied/ACMS/absF20#Markus Deserno (Carnegie Mellon)|Spontaneous curvature, differential stress, and bending modulus of asymmetric lipid membranes]]''<br />
|Spagnolie<br />
|-<br />
| Nov 20<br />
|[https://www.usna.edu/Users/math/lunasin/index.php/ Evelyn Lunasin] (USNA)<br />
|''[[Applied/ACMS/absF20#Evelyn Lunasin (USNA)|TBD]]''<br />
|Jean-Luc & Chen<br />
|-<br />
| Nov 27<br />
|''Thangksgiving recess''<br />
|<br />
|<br />
|-<br />
| Dec 4<br />
||[https://www.math.arizona.edu/people/chertkov Michael Chertkov] (U. Arizona)<br />
|''[[Applied/ACMS/absF20#Michael Chertkov (U Arizona)|TBD]]''<br />
|Zepeda-Nunez<br />
|<br />
|<br />
|-<br />
|}<br />
<br />
== Future semesters ==<br />
<br />
*[[Applied/ACMS/Spring2021|Spring 2021]]<br />
<br />
<br />
----<br />
<br />
== Archived semesters ==<br />
<br />
*[[Applied/ACMS/Spring2020|Spring 2020]]<br />
*[[Applied/ACMS/Fall2019|Fall 2019]]<br />
*[[Applied/ACMS/Spring2019|Spring 2019]]<br />
*[[Applied/ACMS/Fall2018|Fall 2018]]<br />
*[[Applied/ACMS/Spring2018|Spring 2018]]<br />
*[[Applied/ACMS/Fall2017|Fall 2017]]<br />
*[[Applied/ACMS/Spring2017|Spring 2017]]<br />
*[[Applied/ACMS/Fall2016|Fall 2016]]<br />
*[[Applied/ACMS/Spring2016|Spring 2016]]<br />
*[[Applied/ACMS/Fall2015|Fall 2015]]<br />
*[[Applied/ACMS/Spring2015|Spring 2015]]<br />
*[[Applied/ACMS/Fall2014|Fall 2014]]<br />
*[[Applied/ACMS/Spring2014|Spring 2014]]<br />
*[[Applied/ACMS/Fall2013|Fall 2013]]<br />
*[[Applied/ACMS/Spring2013|Spring 2013]]<br />
*[[Applied/ACMS/Fall2012|Fall 2012]]<br />
*[[Applied/ACMS/Spring2012|Spring 2012]]<br />
*[[Applied/ACMS/Fall2011|Fall 2011]]<br />
*[[Applied/ACMS/Spring2011|Spring 2011]]<br />
*[[Applied/ACMS/Fall2010|Fall 2010]]<br />
<!--<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring10.html Spring 2010]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall09.html Fall 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring09.html Spring 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall08.html Fall 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring08.html Spring 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall07.html Fall 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring07.html Spring 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall06.html Fall 2006]<br />
--><br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS/absF20&diff=20305Applied/ACMS/absF202020-11-08T20:16:54Z<p>Spagnolie: /* ACMS Abstracts: Fall 2020 */</p>
<hr />
<div>= ACMS Abstracts: Fall 2020 =<br />
<br />
=== Nick Ouellette (Stanford) ===<br />
<br />
Title: Tensor Geometry in the Turbulent Cascade<br />
<br />
Abstract: Perhaps the defining characteristic of turbulent flows is the directed flux of energy from the scales at which it is injected into the flow to the scales at which it is dissipated. Often, we think about this transfer of energy in a Fourier sense; but in doing so, we obscure its mechanistic origins and lose any connection to the spatial structure of the flow field. Alternatively, quite a bit of work has been done to try to tie the cascade process to flow structures; but such approaches lead to results that seem to be at odds with observations. Here, I will discuss what we can learn from a different way of thinking about the cascade, this time as a purely mechanical process where some scales do work on others and thereby transfer energy. This interpretation highlights the fundamental importance of the geometric alignment between the turbulent stress tensor and the scale-local rate of strain tensor, since if they are misaligned with each other, no work can be done and no energy will be transferred. We find that (perhaps surprisingly) these two tensors are in general quite poorly aligned, making the cascade a highly inefficient process. Our analysis indicates that although some aspects of this tensor alignment are dynamical, the quadratic nature of Navier-Stokes nonlinearity and the embedding dimension provide significant constraints, with potential implications for turbulence modeling.<br />
<br />
<br />
=== Harry Lee (UW Madison) ===<br />
<br />
Title: Recent extension of V.I. Arnold's and J.L. Synge's mathematical theory of shear flows<br />
<br />
Abstract:<br />
A viscous extension of Arnold’s non-viscous theory ([1]) for 2D wall-bounded shear flows is established ([3]). One special form of our linearized viscous theory recaps the linear perturbation’s enstrophy (vorticity) identity derived by Synge in 1938 ([2]). For the first time in literature, we rigorously deduced the validity of Synge’s identity under nonlinear dynamics and relaxed wall conditions. Furthermore, we discovered a new ‘weighted’ enstrophy identity.<br />
<br />
To illustrate the physical relevance of our identities, we quantitatively investigated mechanisms of linear instability/stability within the normal modal framework. We observed a subtle interaction between a critical layer and its adjacent boundary layer, which governs stability/instability of a flow. We also proposed a boundary control scheme that transitions wall settings from no-slip to free-slip, through which the 2D base flow was stabilized quickly at an early stage of the transition. Effectiveness of such boundary control scheme for 3D shear flows is yet to be tested by DNS/experiments.<br />
<br />
Apart from physics, I shall also talk about the potential of using our nonlinear enstrophy identity to generate rigorous bounds on flow stability.<br />
<br />
References:<br />
<br />
[1] V. I. Arnold. Conditions for the nonlinear stability of the stationary plane curvilinear flows of an ideal fluid. Doklady Akademii Nauk, 162:975–978, 1965. URL: https://doi.org/10.1007/978-3-642-31031-7_4.<br />
<br />
[2] F. Fraternale, L. Domenicale, G. Staffilani, and D. Tordella. Internal waves in sheared flows: Lower bound of the vorticity growth and propagation discontinuities in the parameter space. Physical Review E, 97:063102, 2018. URL: https://doi.org/10.1103/PhysRevE.97.063102.<br />
<br />
[3] H. Lee and S. Wang. Extension of classical stability theory to viscous planar wall-bounded shear flows. Journal of Fluid Mechanics, 877:1134– 1162, 2019. URL: https://doi.org/10.1017/jfm.2019.629.<br />
<br />
<br />
=== Spencer Smith (Mount Holyoke) ===<br />
<br />
Title: Braids on a lattice and maximally efficient mixing in active matter systems<br />
<br />
In active matter systems, energy consumed at the small scale by individual agents (like microtubules, bacteria, or birds) gives rise to emergent flows at large scales. Often these flows are chaotic and effectively mix the surrounding medium. In two dimensions, this mixing can be quantified by the topological entropy of the braids formed from the intertwining motion of particle trajectories. It is natural to ask how large this topological entropy, suitably normalized, can get, and what braiding patterns achieve this. For small numbers of particles on a line, or particles on an annulus, braids with topological entropies related to the golden and silver ratios respectively are maximal. Surprisingly, these braids arise in an active matter system: active nematic microtubules confined to an annulus have topological defects that move in trajectories compatible with the silver braid. However, it is unknown what braiding pattern of particles on the plane maximizes topological entropy in an analogous manner. We will investigate this issue in spatially periodic braids defined on planar lattices. Using a newly developed algorithm, we will give numerical evidence for a candidate planar lattice braiding pattern with maximal topological entropy. Using the version of this algorithm for arbitrary flows, we will also highlight a curious mixing phenomenon in the Vicsek active matter model.<br />
<br />
<br />
=== Zhizhen Jane Zhao (UIUC) ===<br />
<br />
Title: Exploiting Group and Geometric Structures for Massive Data Analysis<br />
<br />
Abstract: In this talk, I will introduce a new unsupervised learning framework for data points that lie on or close to a smooth manifold naturally equipped with a group action. In many applications, such as cryo-electron microscopy image analysis and shape analysis, the dataset of interest consists of images or shapes of potentially high spatial resolution, and admits a natural group action that plays the role of a nuisance or latent variable that needs to be quotient out before useful information is revealed. We estimate the pairwise group-invariant distance and the corresponding optimal alignment. We then construct a graph from the dataset, where each vertex represents a data point and the edges connect points with small group-invariant distance. In addition, each edge is associated with the estimated optimal alignment group. Inspired by the vector diffusion maps proposed by Singer and Wu, we explore the cycle consistency of the group transformations under multiple irreducible representations to define new similarity measures for the data. Utilizing the representation theoretic mechanism, multiple associated vector bundles can be constructed over the orbit space, providing multiple views for learning the geometry of the underlying base manifold from noisy observations. I will introduce three approaches to systematically combine the information from different representations, and show that by exploring the redundancy created across irreducible representations of the transformation group, we can significantly improve nearest neighbor identification, when a large portion of the true edge information are corrupted. I will also show the application in cryo-electron microscopy image analysis.<br />
<br />
<br />
=== Matthias Morzfeld (Scripps & UCSD) ===<br />
<br />
Title: What is Bayesian inference, why is it useful in Earth science and why is it challenging to do numerically?<br />
<br />
Abstract:<br />
I will first review Bayesian inference, which means to incorporate information from observations (data) into a numerical model, and will give some examples of applications in Earth science. The numerical solution of Bayesian inference problems is often based on sampling a posterior probability distribution. Sampling posterior distributions is difficult because these are usually high-dimensional (many parameters or states to estimate) and non-standard (e.g., not Gaussian). In particular a high-dimension causes numerical difficulties and slow convergence in many sampling algorithms. I will explain how ideas from numerical weather prediction can be leveraged to design Markov chain Monte Carlo (MCMC) samplers whose convergence rates are independent of the problem dimension for a well-defined class of problems.<br />
<br />
<br />
=== Jingwei Hu (Purdue) ===<br />
<br />
Title: A new stability and convergence proof of the Fourier-Galerkin spectral method for the spatially homogeneous Boltzmann equation<br />
<br />
ABstract: Numerical approximation of the Boltzmann equation is a challenging problem due to its high-dimensional, nonlocal, and nonlinear collision integral. Over the past decade, the Fourier-Galerkin spectral method has become a popular deterministic method for solving the Boltzmann equation, manifested by its high accuracy and potential of being further accelerated by the fast Fourier transform. Albeit its practical success, the stability of the method is only recently proved by Filbet, F. & Mouhot, C. in [Trans.Amer.Math.Soc. 363, no. 4 (2011): 1947-1980.] by utilizing the "spreading" property of the collision operator. In this work, we provide a new proof based on a careful L2 estimate of the negative part of the solution. We also discuss the applicability of the result to various initial data, including both continuous and discontinuous functions. This is joint work with Kunlun Qi and Tong Yang.<br />
<br />
<br />
=== Dan Vimont (UW-Madison, AOS) ===<br />
<br />
Title: Advances in Linear Inverse Modeling for Understanding Tropical Pacific Climate Variability<br />
<br />
Abstract:<br />
The El Nino / Southern Oscillation (ENSO) phenomenon in the tropical Pacific Ocean is the most energetic climatic phenomenon on Earth for interannual to decadal time scales, with substantial societal and environmental impacts around the world. Despite a well-developed theory for why ENSO events occur several aspects of ENSO variability are still poorly understood, including (1) why individual ENSO events tend to evolve with different spatial structures, (2) why ENSO events tend to be positively skewed (toward El Niño events rather than La Niña events), and (3) the role of deterministic dynamics vs. stochastic forcing in influencing ENSO growth and variance. In this talk, I will present recent work using a suite of Linear Inverse Models (LIMs) in which a linear dynamical operator (including state dependent noise, or cyclo-stationary dynamics) is derived from an existing set of observations. These LIMs can be used to (1) diagnose physical processes that cause growth toward a pre-defined spatial structure, (2) investigate how state-dependent (local) correlated additive and multiplicative noise (CAM-Noise) generates higher order moments (in a linear system forced by gaussian noise), and (3) the role of seasonality in generating ENSO variability and predictability. The talk will focus on development of the linear inverse model and on the application of the models in dynamical system analyses.<br />
<br />
<br />
=== Sam Punshon-Smith (Brown) ===<br />
<br />
Title: Scalar mixing and the Batchelor spectrum in stochastic fluid mechanics<br />
<br />
Abstract: In 1959, George Batchelor predicted that a passively advected scalar in a fluid, when the scalar diffusivity is much lower than the fluid viscosity, should display a power spectral density like 1/|k| over an appropriate inertial range. Extending this result beyond Batchelor's simple example of a "pure straining flow" has proven to be a challenge despite the robust nature of the spectrum in a variety of more general physical settings and numerical experiments. In this talk, I will discuss a recent proof of a version of Batchelor's prediction for a variety of random ergodic fluid motions, including the stochastic Navier-Stokes equations on T^2 at fixed Reynolds number. We will see how the spectrum emerges as a consequence of the uniform-in-diffusivity chaotic mixing property of fluid motion, a non-trivial property that makes crucial use of the random motion and the associated uniformity of the chaotic behavior of Lagrangian trajectories.<br />
<br />
<br />
=== Yimin Zhong (Duke) ===<br />
<br />
Title: Quantitative PhotoAcoustic Tomography (PAT) with simplified PN approximation<br />
<br />
Abstract: In this talk, I will first introduce the physical and biomedical background of the quantitative photoacoustic tomography (qPAT). The quantitative step has been traditionally using the diffusion approximation to solve but fails at many scenarios in practice. In recent years, more and more researches start to use the transport model to study this problem. However there are still some open problems relating to the uniqueness and stability estimates. We will try to study the qPAT with the simplified PN approximation which is regarded as a more accurate approximation than the simplest diffusion approximation. I will show that the uniqueness and stability estimates under this formulation. Numerical experiments are performed to validate the theory.<br />
<br />
<br />
=== Markus Deserno (Carnegie Mellon) ===<br />
<br />
Title: Spontaneous curvature, differential stress, and bending modulus of asymmetric lipid membranes<br />
<br />
Abstract: Lipid bilayers can exhibit asymmetric states, in which the physical characteristics of one leaflet differ from those of the other. This most visibly manifests in a different lipid composition, but it can also involve opposing lateral stresses in each leaflet that combine to an overall vanishing membrane tension. In this talk, I will explore the resulting interplay between a compositional asymmetry and a nonvanishing differential stress using both theoretical modeling and coarse-grained simulations. Minimizing the total elastic energy leads to a preferred spontaneous curvature that balances torques due to both bending moments and differential stress, with sometimes unexpected consequences. For instance, asymmetric flat bilayers, whose specific areas in each leaflet are matched to those of corresponding tensionless symmetric flat membranes, still exhibit a residual differential stress because the conditions of vanishing area strain and vanishing bending moment differ. Moreover, measurements of the curvature rigidity of asymmetric bilayers show that a sufficiently strong differential stress, but not compositional asymmetry alone, can increase the bending modulus. The likely cause is a stiffening of the compressed leaflet, which appears to be related to its gel transition but not identical with it. We finally show that the impact of cholesterol on differential stress depends on the relative strength of elastic and thermodynamic driving forces: if cholesterol solvates equally well in both leaflets, it will redistribute to cancel both leaflet tensions almost completely, but if its partitioning free energy prefers one leaflet over the other, the resulting distribution bias may even create differential stress. Because cells keep most of their lipid bilayers in an asymmetric nonequilibrium steady state, these findings suggest that biomembranes are elastically more complex than previously thought: besides a spontaneous curvature, they might also exhibit significant differential stress, which could strongly affect their curvature energetics.</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS/Spring2021&diff=20005Applied/ACMS/Spring20212020-09-28T12:59:45Z<p>Spagnolie: </p>
<hr />
<div>== Spring 2021 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
| Jan 29<br />
|<br />
|<br />
|<br />
|-<br />
| Feb 5<br />
|[https://www.math.wisc.edu/~remondtiedre/ Antoine Remond-Tiedrez] (UW)<br />
|''[[Applied/ACMS/absS21#Antoine Remond-Tiedrez (UW)|TBA]]''<br />
|Spagnolie<br />
|-<br />
| Feb 12<br />
|<br />
|<br />
|<br />
|-<br />
| Feb 19<br />
|<br />
|<br />
|<br />
|-<br />
| Feb 26<br />
|<br />
|<br />
|<br />
|-<br />
| Mar 5<br />
|<br />
|<br />
|<br />
|-<br />
| Mar 12<br />
|[https://www.math.umass.edu/directory/faculty/yulong-lu Yulong Lu] (University of Massachusetts)<br />
|''[[Applied/ACMS/absS21#Yulong Lu (University of Massachusetts)|TBA]]''<br />
|Li<br />
|-<br />
| Mar 19<br />
|<br />
|<br />
|<br />
|-<br />
| Mar 26<br />
|(spring break)<br />
|<br />
|<br />
|-<br />
| Apr 2<br />
|<br />
|<br />
|<br />
|-<br />
| Apr 9<br />
|<br />
|<br />
|<br />
|-<br />
| Apr 16<br />
|<br />
|<br />
|<br />
|-<br />
| Apr 23<br />
|<br />
|<br />
|<br />
|-<br />
|}</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS/Spring2021&diff=20004Applied/ACMS/Spring20212020-09-28T12:58:12Z<p>Spagnolie: </p>
<hr />
<div>== Spring 2021 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
| Jan 29<br />
|<br />
|<br />
|<br />
|-<br />
| Feb 5<br />
|Antoine Remond-Tiedrez (UW)<br />
|<br />
|Spagnolie<br />
|-<br />
| Feb 12<br />
|<br />
|<br />
|<br />
|-<br />
| Feb 19<br />
|<br />
|<br />
|<br />
|-<br />
| Feb 26<br />
|<br />
|<br />
|<br />
|-<br />
| Mar 5<br />
|<br />
|<br />
|<br />
|-<br />
| Mar 12<br />
|[https://www.math.umass.edu/directory/faculty/yulong-lu Yulong Lu] (University of Massachusetts)<br />
|''[[Applied/ACMS/absS21#Yulong Lu (University of Massachusetts)|TBA]]''<br />
|Li<br />
|-<br />
| Mar 19<br />
|<br />
|<br />
|<br />
|-<br />
| Mar 26<br />
|(spring break)<br />
|<br />
|<br />
|-<br />
| Apr 2<br />
|<br />
|<br />
|<br />
|-<br />
| Apr 9<br />
|<br />
|<br />
|<br />
|-<br />
| Apr 16<br />
|<br />
|<br />
|<br />
|-<br />
| Apr 23<br />
|<br />
|<br />
|<br />
|-<br />
|}</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/Physical_Applied_Math&diff=19642Applied/Physical Applied Math2020-09-03T21:50:13Z<p>Spagnolie: </p>
<hr />
<div>= Physical Applied Math Group Meeting =<br />
<br />
*'''When:''' Thursdays at 4:00pm (unless there is a [https://www.math.wisc.edu/deptmeetings Department Meeting])<br />
*'''Where:''' Zoom (contact SES or J-LT for link) <s>901 Van Vleck Hall</s><br />
*'''Organizers:''' [http://www.math.wisc.edu/~spagnolie Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''Announcements:''' Contact SES or J-LT to be added as a guest to our Slack channel.<br />
<br />
== Fall 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
|-<br />
|Sept. 3<br />
|Organizational meeting<br />
|<br />
|-<br />
|Sept. 10<br />
|''no group meeting''<br />
|''faculty meeting @ 3:30pm''<br />
|-<br />
|Sept. 17<br />
|Wil<br />
|<br />
|-<br />
|Sept. 24<br />
|Bryan<br />
|<br />
|-<br />
|Oct 1<br />
|Yu<br />
|<br />
|-<br />
|Oct 8<br />
|Hongfei<br />
|<br />
|-<br />
|Oct 15<br />
|Chris<br />
|<br />
|-<br />
|Oct 22<br />
|<br />
|<br />
|-<br />
|Oct 29<br />
|<br />
|<br />
|-<br />
|Nov 5<br />
|<br />
|<br />
|-<br />
|Nov 12<br />
|<br />
|<br />
|-<br />
|Nov 19<br />
|<br />
|<br />
|-<br />
|Nov 26<br />
|Thanksgiving<br />
|<br />
|-<br />
|Dec 3<br />
|<br />
|<br />
|-<br />
|}<br />
<br />
== Archived semesters ==<br />
*[[Applied/Physical_Applied_Math/Summer2020|Summer 2020]]<br />
*[[Applied/Physical_Applied_Math/Spring2020|Spring 2020]]<br />
*[[Applied/Physical_Applied_Math/Fall2019|Fall 2019]]<br />
*[[Applied/Physical_Applied_Math/Spring2019|Spring 2019]]<br />
*[[Applied/Physical_Applied_Math/Fall2018|Fall 2018]]<br />
*[[Applied/Physical_Applied_Math/Spring2018|Spring 2018]]<br />
*[[Applied/Physical_Applied_Math/Fall2017|Fall 2017]]<br />
*[[Applied/Physical_Applied_Math/Spring2017|Spring 2017]]<br />
*[[Applied/Physical_Applied_Math/Fall2016|Fall 2016]]<br />
*[[Applied/Physical_Applied_Math/Spring2016|Spring 2016]]<br />
*[[Applied/Physical_Applied_Math/Fall2015|Fall 2015]]<br />
*[[Applied/Physical_Applied_Math/Spring2015|Spring 2015]]<br />
*[[Applied/Physical_Applied_Math/Summer2014|Summer 2014]]<br />
*[[Applied/Physical_Applied_Math/Spring2014|Spring 2014]]<br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/Physical_Applied_Math&diff=19641Applied/Physical Applied Math2020-09-03T21:38:29Z<p>Spagnolie: /* Fall 2020 */</p>
<hr />
<div>= Physical Applied Math Group Meeting =<br />
<br />
*'''When:''' Thursdays at 4:00pm (unless there is a [https://www.math.wisc.edu/deptmeetings Department Meeting])<br />
*'''Where:''' Zoom (contact SES or J-LT for link) <s>901 Van Vleck Hall</s><br />
*'''Organizers:''' [http://www.math.wisc.edu/~spagnolie Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''Announcements:''' Contact SES or J-LT to be added as a guest to our Slack channel.<br />
<br />
== Fall 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
|-<br />
|Sept. 3<br />
|Organizational meeting<br />
|<br />
|-<br />
|Sept. 10<br />
|''no group meeting''<br />
|''faculty meeting @ 3:30pm''<br />
|-<br />
|Sept. 17<br />
|<br />
|<br />
|-<br />
|Sept. 24<br />
|<br />
|<br />
|-<br />
|Oct 1<br />
|<br />
|<br />
|-<br />
|Oct 8<br />
|<br />
|<br />
|-<br />
|Oct 15<br />
|<br />
|<br />
|-<br />
|Oct 22<br />
|<br />
|<br />
|-<br />
|Oct 29<br />
|<br />
|<br />
|-<br />
|Nov 5<br />
|<br />
|<br />
|-<br />
|Nov 12<br />
|<br />
|<br />
|-<br />
|Nov 19<br />
|<br />
|<br />
|-<br />
|Nov 26<br />
|<br />
|<br />
|-<br />
|Dec 3<br />
|<br />
|<br />
|-<br />
|}<br />
<br />
== Archived semesters ==<br />
*[[Applied/Physical_Applied_Math/Summer2020|Summer 2020]]<br />
*[[Applied/Physical_Applied_Math/Spring2020|Spring 2020]]<br />
*[[Applied/Physical_Applied_Math/Fall2019|Fall 2019]]<br />
*[[Applied/Physical_Applied_Math/Spring2019|Spring 2019]]<br />
*[[Applied/Physical_Applied_Math/Fall2018|Fall 2018]]<br />
*[[Applied/Physical_Applied_Math/Spring2018|Spring 2018]]<br />
*[[Applied/Physical_Applied_Math/Fall2017|Fall 2017]]<br />
*[[Applied/Physical_Applied_Math/Spring2017|Spring 2017]]<br />
*[[Applied/Physical_Applied_Math/Fall2016|Fall 2016]]<br />
*[[Applied/Physical_Applied_Math/Spring2016|Spring 2016]]<br />
*[[Applied/Physical_Applied_Math/Fall2015|Fall 2015]]<br />
*[[Applied/Physical_Applied_Math/Spring2015|Spring 2015]]<br />
*[[Applied/Physical_Applied_Math/Summer2014|Summer 2014]]<br />
*[[Applied/Physical_Applied_Math/Spring2014|Spring 2014]]<br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/Physical_Applied_Math&diff=19585Applied/Physical Applied Math2020-08-26T19:41:21Z<p>Spagnolie: /* Summer 2020 */</p>
<hr />
<div>= Physical Applied Math Group Meeting =<br />
<br />
*'''When:''' Thursdays at 4:00pm (unless there is a [https://www.math.wisc.edu/deptmeetings Department Meeting])<br />
*'''Where:''' Zoom (contact SES or J-LT for link) <s>901 Van Vleck Hall</s><br />
*'''Organizers:''' [http://www.math.wisc.edu/~spagnolie Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''Announcements:''' Contact SES or J-LT to be added as a guest to our Slack channel.<br />
<br />
== Fall 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
|-<br />
|Sept. 3<br />
|<br />
|<br />
|-<br />
|Sept. 10<br />
|''no group meeting''<br />
|''faculty meeting @ 3:30pm''<br />
|-<br />
|Sept. 17<br />
|<br />
|<br />
|-<br />
|Sept. 24<br />
|<br />
|<br />
|-<br />
|Oct 1<br />
|<br />
|<br />
|-<br />
|Oct 8<br />
|<br />
|<br />
|-<br />
|Oct 15<br />
|<br />
|<br />
|-<br />
|Oct 22<br />
|<br />
|<br />
|-<br />
|Oct 29<br />
|<br />
|<br />
|-<br />
|Nov 5<br />
|<br />
|<br />
|-<br />
|Nov 12<br />
|<br />
|<br />
|-<br />
|Nov 19<br />
|<br />
|<br />
|-<br />
|Nov 26<br />
|<br />
|<br />
|-<br />
|Dec 3<br />
|<br />
|<br />
|-<br />
|}<br />
<br />
== Archived semesters ==<br />
*[[Applied/Physical_Applied_Math/Summer2020|Summer 2020]]<br />
*[[Applied/Physical_Applied_Math/Spring2020|Spring 2020]]<br />
*[[Applied/Physical_Applied_Math/Fall2019|Fall 2019]]<br />
*[[Applied/Physical_Applied_Math/Spring2019|Spring 2019]]<br />
*[[Applied/Physical_Applied_Math/Fall2018|Fall 2018]]<br />
*[[Applied/Physical_Applied_Math/Spring2018|Spring 2018]]<br />
*[[Applied/Physical_Applied_Math/Fall2017|Fall 2017]]<br />
*[[Applied/Physical_Applied_Math/Spring2017|Spring 2017]]<br />
*[[Applied/Physical_Applied_Math/Fall2016|Fall 2016]]<br />
*[[Applied/Physical_Applied_Math/Spring2016|Spring 2016]]<br />
*[[Applied/Physical_Applied_Math/Fall2015|Fall 2015]]<br />
*[[Applied/Physical_Applied_Math/Spring2015|Spring 2015]]<br />
*[[Applied/Physical_Applied_Math/Summer2014|Summer 2014]]<br />
*[[Applied/Physical_Applied_Math/Spring2014|Spring 2014]]<br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/Physical_Applied_Math/Summer2020&diff=19584Applied/Physical Applied Math/Summer20202020-08-26T19:37:51Z<p>Spagnolie: Created page with "== Summer 2020 == {| cellpadding="8" !align="left" | date !align="left" | speaker !align="left" | title |- |May 14 |''video party'' |Ken Millett, [https://www.youtube.com/w..."</p>
<hr />
<div>== Summer 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
|-<br />
|May 14<br />
|''video party''<br />
|Ken Millett, [https://www.youtube.com/watch?v=JSVE-ukefPg Entanglement of Polymers]<br />
|-<br />
|May 21<br />
|Saverio<br />
|Flagellar locomotion<br />
|-<br />
|May 28<br />
|''video party''<br />
|Gareth Alexander, [https://www.youtube.com/watch?v=NKNkequdrVs&feature=emb_logo Geometric Topology of Liquid Crystal Textures]<br />
|-<br />
|June 4<br />
|Hongfei<br />
|[https://www.dropbox.com/s/nqnbkujpnbxn0mo/Rayleigh_1892_On%20the%20influence%20of%20obstacles%20arranged%20in%20rectangular%20order%20upon%20the.pdf Rayleigh's solution of diffusion in a lattice]<br />
|-<br />
|June 11<br />
|''video party''<br />
|Isabelle Gallagher, [https://youtu.be/BkrKkUVadDo From Newton to Boltzmann, fluctuations and large deviations]<br />
|-<br />
|June 18<br />
|Jean-Luc<br />
|Correlations in the active Brownian particle model<br />
|-<br />
|June 25<br />
|''video party''<br />
|Mark Embree, [https://www.youtube.com/watch?v=m-2tZs1398Y Contour integral methods for nonlinear eigenvalue problems]<br />
|-<br />
|July 2<br />
|''no meeting''<br />
|''watch WHOI-GFD lectures instead''<br />
|-<br />
|July 9<br />
|Eduardo Vitral<br />
|Mesoscale models for soft layered materials: the role of curvatures in topological defect motion, flows and instabilities<br />
|-<br />
|July 16<br />
|''no meeting''<br />
|''watch Jean-Luc's lecture in Phil Morrison's group on July 17''<br />
|-<br />
|July 23<br />
|''video party''<br />
|Nick Trefethen, Von Neumann Lecture at SIAM AN20<br />
|-<br />
|July 30<br />
|''video party''<br />
|David Nelson, [http://online.kitp.ucsb.edu/online/active20/nelson/ Active Antagonism: Reproducing Microorganisms and Fluid Flow ]<br />
|-<br />
<br />
|}</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/Physical_Applied_Math&diff=19583Applied/Physical Applied Math2020-08-26T19:37:37Z<p>Spagnolie: /* Archived semesters */</p>
<hr />
<div>= Physical Applied Math Group Meeting =<br />
<br />
*'''When:''' Thursdays at 4:00pm (unless there is a [https://www.math.wisc.edu/deptmeetings Department Meeting])<br />
*'''Where:''' Zoom (contact SES or J-LT for link) <s>901 Van Vleck Hall</s><br />
*'''Organizers:''' [http://www.math.wisc.edu/~spagnolie Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''Announcements:''' Contact SES or J-LT to be added as a guest to our Slack channel.<br />
<br />
== Summer 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
|-<br />
|May 14<br />
|''video party''<br />
|Ken Millett, [https://www.youtube.com/watch?v=JSVE-ukefPg Entanglement of Polymers]<br />
|-<br />
|May 21<br />
|Saverio<br />
|Flagellar locomotion<br />
|-<br />
|May 28<br />
|''video party''<br />
|Gareth Alexander, [https://www.youtube.com/watch?v=NKNkequdrVs&feature=emb_logo Geometric Topology of Liquid Crystal Textures]<br />
|-<br />
|June 4<br />
|Hongfei<br />
|[https://www.dropbox.com/s/nqnbkujpnbxn0mo/Rayleigh_1892_On%20the%20influence%20of%20obstacles%20arranged%20in%20rectangular%20order%20upon%20the.pdf Rayleigh's solution of diffusion in a lattice]<br />
|-<br />
|June 11<br />
|''video party''<br />
|Isabelle Gallagher, [https://youtu.be/BkrKkUVadDo From Newton to Boltzmann, fluctuations and large deviations]<br />
|-<br />
|June 18<br />
|Jean-Luc<br />
|Correlations in the active Brownian particle model<br />
|-<br />
|June 25<br />
|''video party''<br />
|Mark Embree, [https://www.youtube.com/watch?v=m-2tZs1398Y Contour integral methods for nonlinear eigenvalue problems]<br />
|-<br />
|July 2<br />
|''no meeting''<br />
|''watch WHOI-GFD lectures instead''<br />
|-<br />
|July 9<br />
|Eduardo Vitral<br />
|Mesoscale models for soft layered materials: the role of curvatures in topological defect motion, flows and instabilities<br />
|-<br />
|July 16<br />
|''no meeting''<br />
|''watch Jean-Luc's lecture in Phil Morrison's group on July 17''<br />
|-<br />
|July 23<br />
|''video party''<br />
|Nick Trefethen, Von Neumann Lecture at SIAM AN20<br />
|-<br />
|July 30<br />
|''video party''<br />
|David Nelson, [http://online.kitp.ucsb.edu/online/active20/nelson/ Active Antagonism: Reproducing Microorganisms and Fluid Flow ]<br />
|-<br />
<br />
|}<br />
<br />
== Archived semesters ==<br />
*[[Applied/Physical_Applied_Math/Summer2020|Summer 2020]]<br />
*[[Applied/Physical_Applied_Math/Spring2020|Spring 2020]]<br />
*[[Applied/Physical_Applied_Math/Fall2019|Fall 2019]]<br />
*[[Applied/Physical_Applied_Math/Spring2019|Spring 2019]]<br />
*[[Applied/Physical_Applied_Math/Fall2018|Fall 2018]]<br />
*[[Applied/Physical_Applied_Math/Spring2018|Spring 2018]]<br />
*[[Applied/Physical_Applied_Math/Fall2017|Fall 2017]]<br />
*[[Applied/Physical_Applied_Math/Spring2017|Spring 2017]]<br />
*[[Applied/Physical_Applied_Math/Fall2016|Fall 2016]]<br />
*[[Applied/Physical_Applied_Math/Spring2016|Spring 2016]]<br />
*[[Applied/Physical_Applied_Math/Fall2015|Fall 2015]]<br />
*[[Applied/Physical_Applied_Math/Spring2015|Spring 2015]]<br />
*[[Applied/Physical_Applied_Math/Summer2014|Summer 2014]]<br />
*[[Applied/Physical_Applied_Math/Spring2014|Spring 2014]]<br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS&diff=19541Applied/ACMS2020-08-14T00:30:04Z<p>Spagnolie: /* Fall 2020 */</p>
<hr />
<div>__NOTOC__<br />
<br />
= Applied and Computational Mathematics Seminar =<br />
<br />
*'''When:''' Fridays at 2:25pm (except as otherwise indicated)<br />
*'''Where:''' 901 Van Vleck Hall<br />
*'''Organizers:''' [http://www.math.wisc.edu/~qinli/ Qin Li], [http://www.math.wisc.edu/~spagnolie/ Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''To join the ACMS mailing list:''' See [https://admin.lists.wisc.edu/index.php?p=11&l=acms mailing list] website.<br />
<br />
<br><br />
<br />
<br />
== Fall 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
| Sep 11<br />
|[https://cee.stanford.edu/people/nicholas-ouellette Nick Ouellette] (Stanford)<br />
|''[[Applied/ACMS/absF20#Nick Ouellette (Stanford)|Tensor Geometry in the Turbulent Cascade]]''<br />
|Jean-Luc<br />
|-<br />
| Sep 18<br />
|[https://www.researchgate.net/profile/Harry_Lee24 Harry Lee] (UW-Madison and UMich)<br />
|''[[Applied/ACMS/absF20#Harry Lee (UW-Madison, UMich)|TBD]]''<br />
|Wally<br />
|-<br />
| Sep 25<br />
|[https://www.mtholyoke.edu/people/spencer-smith Spencer Smith] (Mount Holyoke)<br />
|''[[Applied/ACMS/absF20#Spencer Smith (Mount Holyoke)|TBD]]''<br />
|Jean-Luc<br />
|-<br />
| Oct 2<br />
|[https://zhizhenz.ece.illinois.edu/ Zhizhen Jane Zhao] (UIUC)<br />
|''[[Applied/ACMS/absF20#Zhizhen Jane Zhao (UIUC)|TBD]]''<br />
| Li<br />
|<br />
|<br />
|-<br />
| Oct 9<br />
|[https://igppweb.ucsd.edu/~mmorzfeld/ Matthias Morzfeld] (Scripps & UCSD)<br />
|''[[Applied/ACMS/absF20#Matthias Morzfeld (Scripps & UCSD)|TBD]]''<br />
| Chen<br />
|<br />
|<br />
|-<br />
| Oct 16<br />
|[https://jingweihu-math.github.io/webpage/ Jingwei Hu] (Purdue)<br />
|''[[Applied/ACMS/absF20#Jingwei Hu (Purdue)|TBD]]''<br />
| Li<br />
|<br />
|-<br />
| Oct 23<br />
|<br />
|<br />
|<br />
|-<br />
| Oct 30<br />
|<br />
|<br />
|<br />
|-<br />
| Nov 6<br />
|<br />
|<br />
|<br />
|-<br />
| Nov 13<br />
|[https://www.cmu.edu/biolphys/deserno/ Markus Deserno] (CMU)<br />
|''[[Applied/ACMS/absF20#Markus Deserno (CMU)|Spontaneous curvature, differential stress, and bending modulus of asymmetric lipid membranes]]''<br />
|Spagnolie<br />
|-<br />
| Nov 20<br />
|<br />
|<br />
|<br />
|-<br />
| Nov 27<br />
|<br />
|<br />
|<br />
|-<br />
| Dec 4<br />
|<br />
|<br />
|<br />
|-<br />
|}<br />
<br />
== Future semesters ==<br />
<br />
*[[Applied/ACMS/Spring2021|Spring 2021]]<br />
<br />
<br />
----<br />
<br />
== Archived semesters ==<br />
<br />
*[[Applied/ACMS/Spring2020|Spring 2020]]<br />
*[[Applied/ACMS/Fall2019|Fall 2019]]<br />
*[[Applied/ACMS/Spring2019|Spring 2019]]<br />
*[[Applied/ACMS/Fall2018|Fall 2018]]<br />
*[[Applied/ACMS/Spring2018|Spring 2018]]<br />
*[[Applied/ACMS/Fall2017|Fall 2017]]<br />
*[[Applied/ACMS/Spring2017|Spring 2017]]<br />
*[[Applied/ACMS/Fall2016|Fall 2016]]<br />
*[[Applied/ACMS/Spring2016|Spring 2016]]<br />
*[[Applied/ACMS/Fall2015|Fall 2015]]<br />
*[[Applied/ACMS/Spring2015|Spring 2015]]<br />
*[[Applied/ACMS/Fall2014|Fall 2014]]<br />
*[[Applied/ACMS/Spring2014|Spring 2014]]<br />
*[[Applied/ACMS/Fall2013|Fall 2013]]<br />
*[[Applied/ACMS/Spring2013|Spring 2013]]<br />
*[[Applied/ACMS/Fall2012|Fall 2012]]<br />
*[[Applied/ACMS/Spring2012|Spring 2012]]<br />
*[[Applied/ACMS/Fall2011|Fall 2011]]<br />
*[[Applied/ACMS/Spring2011|Spring 2011]]<br />
*[[Applied/ACMS/Fall2010|Fall 2010]]<br />
<!--<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring10.html Spring 2010]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall09.html Fall 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring09.html Spring 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall08.html Fall 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring08.html Spring 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall07.html Fall 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring07.html Spring 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall06.html Fall 2006]<br />
--><br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/Physical_Applied_Math&diff=19438Applied/Physical Applied Math2020-06-29T22:58:59Z<p>Spagnolie: /* Summer 2020 */</p>
<hr />
<div>= Physical Applied Math Group Meeting =<br />
<br />
*'''When:''' Thursdays at 4:00pm (unless there is a [https://www.math.wisc.edu/deptmeetings Department Meeting])<br />
*'''Where:''' Zoom (contact SES or J-LT for link) <s>901 Van Vleck Hall</s><br />
*'''Organizers:''' [http://www.math.wisc.edu/~spagnolie Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''Announcements:''' Contact SES or J-LT to be added as a guest to our Slack channel.<br />
<br />
== Summer 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
|-<br />
|May 14<br />
|''video party''<br />
|Ken Millett, [https://www.youtube.com/watch?v=JSVE-ukefPg Entanglement of Polymers]<br />
|-<br />
|May 21<br />
|Saverio<br />
|Flagellar locomotion<br />
|-<br />
|May 28<br />
|''video party''<br />
|Gareth Alexander, [https://www.youtube.com/watch?v=NKNkequdrVs&feature=emb_logo Geometric Topology of Liquid Crystal Textures]<br />
|-<br />
|June 4<br />
|Hongfei<br />
|[https://www.dropbox.com/s/nqnbkujpnbxn0mo/Rayleigh_1892_On%20the%20influence%20of%20obstacles%20arranged%20in%20rectangular%20order%20upon%20the.pdf Rayleigh's solution of diffusion in a lattice]<br />
|-<br />
|June 11<br />
|''video party''<br />
|Isabelle Gallagher, [https://youtu.be/BkrKkUVadDo From Newton to Boltzmann, fluctuations and large deviations]<br />
|-<br />
|June 18<br />
|Jean-Luc<br />
|Correlations in the active Brownian particle model<br />
|-<br />
|June 25<br />
|''video party''<br />
|Mark Embree, [https://www.youtube.com/watch?v=m-2tZs1398Y Contour integral methods for nonlinear eigenvalue problems]<br />
|-<br />
|July 9<br />
|Eduardo Vitral<br />
|<br />
|-<br />
<br />
|}<br />
<br />
== Archived semesters ==<br />
*[[Applied/Physical_Applied_Math/Spring2020|Spring 2020]]<br />
*[[Applied/Physical_Applied_Math/Fall2019|Fall 2019]]<br />
*[[Applied/Physical_Applied_Math/Spring2019|Spring 2019]]<br />
*[[Applied/Physical_Applied_Math/Fall2018|Fall 2018]]<br />
*[[Applied/Physical_Applied_Math/Spring2018|Spring 2018]]<br />
*[[Applied/Physical_Applied_Math/Fall2017|Fall 2017]]<br />
*[[Applied/Physical_Applied_Math/Spring2017|Spring 2017]]<br />
*[[Applied/Physical_Applied_Math/Fall2016|Fall 2016]]<br />
*[[Applied/Physical_Applied_Math/Spring2016|Spring 2016]]<br />
*[[Applied/Physical_Applied_Math/Fall2015|Fall 2015]]<br />
*[[Applied/Physical_Applied_Math/Spring2015|Spring 2015]]<br />
*[[Applied/Physical_Applied_Math/Summer2014|Summer 2014]]<br />
*[[Applied/Physical_Applied_Math/Spring2014|Spring 2014]]<br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS&diff=19430Applied/ACMS2020-06-08T15:39:29Z<p>Spagnolie: /* Spring 2020 */</p>
<hr />
<div>__NOTOC__<br />
<br />
= Applied and Computational Mathematics Seminar =<br />
<br />
*'''When:''' Fridays at 2:25pm (except as otherwise indicated)<br />
*'''Where:''' 901 Van Vleck Hall<br />
*'''Organizers:''' [http://www.math.wisc.edu/~qinli/ Qin Li], [http://www.math.wisc.edu/~spagnolie/ Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''To join the ACMS mailing list:''' See [https://admin.lists.wisc.edu/index.php?p=11&l=acms mailing list] website.<br />
<br />
<br><br />
<br />
<br />
== Fall 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
| Sep 11<br />
|<br />
|<br />
|<br />
|-<br />
| Sep 18<br />
|<br />
|<br />
|<br />
|-<br />
| Sep 25<br />
|<br />
|<br />
|<br />
|-<br />
| Oct 2<br />
|<br />
|<br />
|<br />
|-<br />
| Oct 9<br />
|<br />
|<br />
|<br />
|-<br />
| Oct 16<br />
|<br />
|<br />
|<br />
|-<br />
| Oct 23<br />
|<br />
|<br />
|<br />
|-<br />
| Oct 30<br />
|<br />
|<br />
|<br />
|-<br />
| Nov 6<br />
|<br />
|<br />
|<br />
|-<br />
| Nov 13<br />
|<br />
|<br />
|<br />
|-<br />
| Nov 20<br />
|<br />
|<br />
|<br />
|-<br />
| Nov 27<br />
|<br />
|<br />
|<br />
|-<br />
| Dec 4<br />
|<br />
|<br />
|<br />
|-<br />
|}<br />
<br />
== Future semesters ==<br />
<br />
*[[Applied/ACMS/Spring2021|Spring 2021]]<br />
<br />
<br />
----<br />
<br />
== Archived semesters ==<br />
<br />
*[[Applied/ACMS/Spring2020|Spring 2020]]<br />
*[[Applied/ACMS/Fall2019|Fall 2019]]<br />
*[[Applied/ACMS/Spring2019|Spring 2019]]<br />
*[[Applied/ACMS/Fall2018|Fall 2018]]<br />
*[[Applied/ACMS/Spring2018|Spring 2018]]<br />
*[[Applied/ACMS/Fall2017|Fall 2017]]<br />
*[[Applied/ACMS/Spring2017|Spring 2017]]<br />
*[[Applied/ACMS/Fall2016|Fall 2016]]<br />
*[[Applied/ACMS/Spring2016|Spring 2016]]<br />
*[[Applied/ACMS/Fall2015|Fall 2015]]<br />
*[[Applied/ACMS/Spring2015|Spring 2015]]<br />
*[[Applied/ACMS/Fall2014|Fall 2014]]<br />
*[[Applied/ACMS/Spring2014|Spring 2014]]<br />
*[[Applied/ACMS/Fall2013|Fall 2013]]<br />
*[[Applied/ACMS/Spring2013|Spring 2013]]<br />
*[[Applied/ACMS/Fall2012|Fall 2012]]<br />
*[[Applied/ACMS/Spring2012|Spring 2012]]<br />
*[[Applied/ACMS/Fall2011|Fall 2011]]<br />
*[[Applied/ACMS/Spring2011|Spring 2011]]<br />
*[[Applied/ACMS/Fall2010|Fall 2010]]<br />
<!--<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring10.html Spring 2010]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall09.html Fall 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring09.html Spring 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall08.html Fall 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring08.html Spring 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall07.html Fall 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring07.html Spring 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall06.html Fall 2006]<br />
--><br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS/Spring2021&diff=19429Applied/ACMS/Spring20212020-06-08T15:35:53Z<p>Spagnolie: Created page with "== Spring 2021 == {| cellpadding="8" !align="left" | date !align="left" | speaker !align="left" | title !align="left" | host(s) |- | Jan 29 | | | |- | Feb 5 | | | |- | Feb..."</p>
<hr />
<div>== Spring 2021 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
| Jan 29<br />
|<br />
|<br />
|<br />
|-<br />
| Feb 5<br />
|<br />
|<br />
|<br />
|-<br />
| Feb 12<br />
|<br />
|<br />
|<br />
|-<br />
| Feb 19<br />
|<br />
|<br />
|<br />
|-<br />
| Feb 26<br />
|<br />
|<br />
|<br />
|-<br />
| Mar 5<br />
|<br />
|<br />
|<br />
|-<br />
| Mar 12<br />
|<br />
|<br />
|<br />
|-<br />
| Mar 19<br />
|<br />
|<br />
|<br />
|-<br />
| Mar 26<br />
|(spring break)<br />
|<br />
|<br />
|-<br />
| Apr 2<br />
|<br />
|<br />
|<br />
|-<br />
| Apr 9<br />
|<br />
|<br />
|<br />
|-<br />
| Apr 16<br />
|<br />
|<br />
|<br />
|-<br />
| Apr 23<br />
|<br />
|<br />
|<br />
|-<br />
|}</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS&diff=19428Applied/ACMS2020-06-08T15:32:00Z<p>Spagnolie: /* Future semesters */</p>
<hr />
<div>__NOTOC__<br />
<br />
= Applied and Computational Mathematics Seminar =<br />
<br />
*'''When:''' Fridays at 2:25pm (except as otherwise indicated)<br />
*'''Where:''' 901 Van Vleck Hall<br />
*'''Organizers:''' [http://www.math.wisc.edu/~qinli/ Qin Li], [http://www.math.wisc.edu/~spagnolie/ Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''To join the ACMS mailing list:''' See [https://admin.lists.wisc.edu/index.php?p=11&l=acms mailing list] website.<br />
<br />
<br><br />
<br />
<br />
== Spring 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
| Jan 31<br />
|[https://www.math.wisc.edu/~hung/ Hung Tran] (UW-Madison)<br />
|''[[Applied/ACMS/absS20#Hung Tran (UW-Madison)| Coagulation-Fragmentation equations with multiplicative coagulation kernel and constant fragmentation kernel]]''<br />
| Li<br />
|-<br />
| Feb 7<br />
|[https://www.usna.edu/Users/weaprcon/avramov/index.php Svetlana Avramov-Zamurovic] (United States Naval Academy)<br />
|''[[Applied/ACMS/absS20#Svetlana Avramov-Zamurovic (United States Naval Academy)|Experiments with Structured Light]]''<br />
| Stechmann<br />
|-<br />
| Feb 14<br />
|[http://math.mit.edu/~vadicgor/ Vadim Gorin] (UW-Madison)<br />
|''[[Applied/ACMS/absS20#Vadim Gorin (UW-Madison)| Integrability of KPZ equation]]''<br />
| Li<br />
|-<br />
| Feb 21<br />
|[http://www.personal.psu.edu/jzh13/ John Harlim] (Penn State University)<br />
|''[[Applied/ACMS/absS20#Speaker (Penn State University)|Modeling Dynamical Systems with Machine Learning]]''<br />
| Chen<br />
|-<br />
| Feb 28<br />
|[https://cims.nyu.edu/~yangq/ Qiu Yang] (NYU/UVic/NCAR)<br />
|''[[Applied/ACMS/absS20#Speaker (NYU/UVic/NCAR)|Upscale Impact of Mesoscale Convective Systems on the MJO and Its Parameterization in Coarse-Resolution GCMs]]''<br />
| Chen<br />
|-<br />
| Mar 6<br />
|[https://directory.engr.wisc.edu/ep/Faculty/Bronkhorst_Curt/ Curt Bronkhorst] (UW-Madison Engineering Physics)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|Computational Prediction of Shear Banding and Deformation Twinning in Metals]]''<br />
| Smith<br />
|-<br />
| Mar 13<br />
|[http://www.columbia.edu/~ktm2132/ Kyle Mandli] (Columbia)<br />
|''[[Applied/ACMS/absS20#Kyle Mandli (Columbia)|canceled]]''<br />
| Wally<br />
|-<br />
| Mar 20<br />
|[Spring break] (Spring Break!)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|title]]''<br />
| host<br />
|-<br />
| Mar 27<br />
|[http://www-personal.umich.edu/~jcsch/ John Schotland] (U Mich)<br />
|''[[Applied/ACMS/absS20#John Schotland (Michigan)|canceled]]''<br />
| host<br />
|-<br />
| Apr 3<br />
|[http://keaton-burns.com/ Keaton Burns] (MIT)<br />
|''[[Applied/ACMS/absS20#Keaton Burns (MIT)| Flexible spectral methods and high-level programming for PDEs]]'' <br />
(Virtual, link to recording [https://www.math.wisc.edu/~appliedmathlab/Seminars/ACMS_040220_Burns.mp4 here])<br />
| Spagnolie<br />
|-<br />
| Apr 10<br />
|[https://www.princeton.edu/~lecoanet/ Daniel Lecoanet] (Princeton)<br />
|''[[Applied/ACMS/absS20#Daniel Lecoanet (Princeton)|canceled]]''<br />
| Wally<br />
|-<br />
| Apr 17<br />
|[https://www.ornl.gov/staff-profile/hoang-tran Hoang Tran] (Oak Ridge National Laboratory)<br />
|''[[Applied/ACMS/absS20#Hoang Tran (institution)|canceled]]''<br />
| Tran<br />
|-<br />
| Apr 24<br />
|[https://www.pml.unc.edu/ Pedro Saenz] (UNC)<br />
|''[[Applied/ACMS/absF19#Pedro Saenz (UNC)|canceled]]''<br />
| Spagnolie<br />
|-<br />
|}<br />
<br />
== Future semesters ==<br />
<br />
*[[Applied/ACMS/Spring2021|Spring 2021]]<br />
<br />
<br />
----<br />
<br />
== Archived semesters ==<br />
<br />
*[[Applied/ACMS/Spring2020|Spring 2020]]<br />
*[[Applied/ACMS/Fall2019|Fall 2019]]<br />
*[[Applied/ACMS/Spring2019|Spring 2019]]<br />
*[[Applied/ACMS/Fall2018|Fall 2018]]<br />
*[[Applied/ACMS/Spring2018|Spring 2018]]<br />
*[[Applied/ACMS/Fall2017|Fall 2017]]<br />
*[[Applied/ACMS/Spring2017|Spring 2017]]<br />
*[[Applied/ACMS/Fall2016|Fall 2016]]<br />
*[[Applied/ACMS/Spring2016|Spring 2016]]<br />
*[[Applied/ACMS/Fall2015|Fall 2015]]<br />
*[[Applied/ACMS/Spring2015|Spring 2015]]<br />
*[[Applied/ACMS/Fall2014|Fall 2014]]<br />
*[[Applied/ACMS/Spring2014|Spring 2014]]<br />
*[[Applied/ACMS/Fall2013|Fall 2013]]<br />
*[[Applied/ACMS/Spring2013|Spring 2013]]<br />
*[[Applied/ACMS/Fall2012|Fall 2012]]<br />
*[[Applied/ACMS/Spring2012|Spring 2012]]<br />
*[[Applied/ACMS/Fall2011|Fall 2011]]<br />
*[[Applied/ACMS/Spring2011|Spring 2011]]<br />
*[[Applied/ACMS/Fall2010|Fall 2010]]<br />
<!--<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring10.html Spring 2010]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall09.html Fall 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring09.html Spring 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall08.html Fall 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring08.html Spring 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall07.html Fall 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring07.html Spring 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall06.html Fall 2006]<br />
--><br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS/Spring2020&diff=19427Applied/ACMS/Spring20202020-06-08T15:31:17Z<p>Spagnolie: </p>
<hr />
<div>== Spring 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
| Jan 31<br />
|[https://www.math.wisc.edu/~hung/ Hung Tran] (UW-Madison)<br />
|''[[Applied/ACMS/absS20#Hung Tran (UW-Madison)| Coagulation-Fragmentation equations with multiplicative coagulation kernel and constant fragmentation kernel]]''<br />
| Li<br />
|-<br />
| Feb 7<br />
|[https://www.usna.edu/Users/weaprcon/avramov/index.php Svetlana Avramov-Zamurovic] (United States Naval Academy)<br />
|''[[Applied/ACMS/absS20#Svetlana Avramov-Zamurovic (United States Naval Academy)|Experiments with Structured Light]]''<br />
| Stechmann<br />
|-<br />
| Feb 14<br />
|[http://math.mit.edu/~vadicgor/ Vadim Gorin] (UW-Madison)<br />
|''[[Applied/ACMS/absS20#Vadim Gorin (UW-Madison)| Integrability of KPZ equation]]''<br />
| Li<br />
|-<br />
| Feb 21<br />
|[http://www.personal.psu.edu/jzh13/ John Harlim] (Penn State University)<br />
|''[[Applied/ACMS/absS20#Speaker (Penn State University)|Modeling Dynamical Systems with Machine Learning]]''<br />
| Chen<br />
|-<br />
| Feb 28<br />
|[https://cims.nyu.edu/~yangq/ Qiu Yang] (NYU/UVic/NCAR)<br />
|''[[Applied/ACMS/absS20#Speaker (NYU/UVic/NCAR)|Upscale Impact of Mesoscale Convective Systems on the MJO and Its Parameterization in Coarse-Resolution GCMs]]''<br />
| Chen<br />
|-<br />
| Mar 6<br />
|[https://directory.engr.wisc.edu/ep/Faculty/Bronkhorst_Curt/ Curt Bronkhorst] (UW-Madison Engineering Physics)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|Computational Prediction of Shear Banding and Deformation Twinning in Metals]]''<br />
| Smith<br />
|-<br />
| Mar 13<br />
|[http://www.columbia.edu/~ktm2132/ Kyle Mandli] (Columbia)<br />
|''[[Applied/ACMS/absS20#Kyle Mandli (Columbia)|canceled]]''<br />
| Wally<br />
|-<br />
| Mar 20<br />
|[Spring break] (Spring Break!)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|title]]''<br />
| host<br />
|-<br />
| Mar 27<br />
|[http://www-personal.umich.edu/~jcsch/ John Schotland] (U Mich)<br />
|''[[Applied/ACMS/absS20#John Schotland (Michigan)|canceled]]''<br />
| host<br />
|-<br />
| Apr 3<br />
|[http://keaton-burns.com/ Keaton Burns] (MIT)<br />
|''[[Applied/ACMS/absS20#Keaton Burns (MIT)| Flexible spectral methods and high-level programming for PDEs]]'' <br />
(Virtual, link to recording [https://www.math.wisc.edu/~appliedmathlab/Seminars/ACMS_040220_Burns.mp4 here])<br />
| Spagnolie<br />
|-<br />
| Apr 10<br />
|[https://www.princeton.edu/~lecoanet/ Daniel Lecoanet] (Princeton)<br />
|''[[Applied/ACMS/absS20#Daniel Lecoanet (Princeton)|canceled]]''<br />
| Wally<br />
|-<br />
| Apr 17<br />
|[https://www.ornl.gov/staff-profile/hoang-tran Hoang Tran] (Oak Ridge National Laboratory)<br />
|''[[Applied/ACMS/absS20#Hoang Tran (institution)|canceled]]''<br />
| Tran<br />
|-<br />
| Apr 24<br />
|[https://www.pml.unc.edu/ Pedro Saenz] (UNC)<br />
|''[[Applied/ACMS/absF19#Pedro Saenz (UNC)|canceled]]''<br />
| Spagnolie<br />
|-<br />
|}</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS&diff=19426Applied/ACMS2020-06-08T15:31:06Z<p>Spagnolie: /* Archived semesters */</p>
<hr />
<div>__NOTOC__<br />
<br />
= Applied and Computational Mathematics Seminar =<br />
<br />
*'''When:''' Fridays at 2:25pm (except as otherwise indicated)<br />
*'''Where:''' 901 Van Vleck Hall<br />
*'''Organizers:''' [http://www.math.wisc.edu/~qinli/ Qin Li], [http://www.math.wisc.edu/~spagnolie/ Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''To join the ACMS mailing list:''' See [https://admin.lists.wisc.edu/index.php?p=11&l=acms mailing list] website.<br />
<br />
<br><br />
<br />
<br />
== Spring 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
| Jan 31<br />
|[https://www.math.wisc.edu/~hung/ Hung Tran] (UW-Madison)<br />
|''[[Applied/ACMS/absS20#Hung Tran (UW-Madison)| Coagulation-Fragmentation equations with multiplicative coagulation kernel and constant fragmentation kernel]]''<br />
| Li<br />
|-<br />
| Feb 7<br />
|[https://www.usna.edu/Users/weaprcon/avramov/index.php Svetlana Avramov-Zamurovic] (United States Naval Academy)<br />
|''[[Applied/ACMS/absS20#Svetlana Avramov-Zamurovic (United States Naval Academy)|Experiments with Structured Light]]''<br />
| Stechmann<br />
|-<br />
| Feb 14<br />
|[http://math.mit.edu/~vadicgor/ Vadim Gorin] (UW-Madison)<br />
|''[[Applied/ACMS/absS20#Vadim Gorin (UW-Madison)| Integrability of KPZ equation]]''<br />
| Li<br />
|-<br />
| Feb 21<br />
|[http://www.personal.psu.edu/jzh13/ John Harlim] (Penn State University)<br />
|''[[Applied/ACMS/absS20#Speaker (Penn State University)|Modeling Dynamical Systems with Machine Learning]]''<br />
| Chen<br />
|-<br />
| Feb 28<br />
|[https://cims.nyu.edu/~yangq/ Qiu Yang] (NYU/UVic/NCAR)<br />
|''[[Applied/ACMS/absS20#Speaker (NYU/UVic/NCAR)|Upscale Impact of Mesoscale Convective Systems on the MJO and Its Parameterization in Coarse-Resolution GCMs]]''<br />
| Chen<br />
|-<br />
| Mar 6<br />
|[https://directory.engr.wisc.edu/ep/Faculty/Bronkhorst_Curt/ Curt Bronkhorst] (UW-Madison Engineering Physics)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|Computational Prediction of Shear Banding and Deformation Twinning in Metals]]''<br />
| Smith<br />
|-<br />
| Mar 13<br />
|[http://www.columbia.edu/~ktm2132/ Kyle Mandli] (Columbia)<br />
|''[[Applied/ACMS/absS20#Kyle Mandli (Columbia)|canceled]]''<br />
| Wally<br />
|-<br />
| Mar 20<br />
|[Spring break] (Spring Break!)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|title]]''<br />
| host<br />
|-<br />
| Mar 27<br />
|[http://www-personal.umich.edu/~jcsch/ John Schotland] (U Mich)<br />
|''[[Applied/ACMS/absS20#John Schotland (Michigan)|canceled]]''<br />
| host<br />
|-<br />
| Apr 3<br />
|[http://keaton-burns.com/ Keaton Burns] (MIT)<br />
|''[[Applied/ACMS/absS20#Keaton Burns (MIT)| Flexible spectral methods and high-level programming for PDEs]]'' <br />
(Virtual, link to recording [https://www.math.wisc.edu/~appliedmathlab/Seminars/ACMS_040220_Burns.mp4 here])<br />
| Spagnolie<br />
|-<br />
| Apr 10<br />
|[https://www.princeton.edu/~lecoanet/ Daniel Lecoanet] (Princeton)<br />
|''[[Applied/ACMS/absS20#Daniel Lecoanet (Princeton)|canceled]]''<br />
| Wally<br />
|-<br />
| Apr 17<br />
|[https://www.ornl.gov/staff-profile/hoang-tran Hoang Tran] (Oak Ridge National Laboratory)<br />
|''[[Applied/ACMS/absS20#Hoang Tran (institution)|canceled]]''<br />
| Tran<br />
|-<br />
| Apr 24<br />
|[https://www.pml.unc.edu/ Pedro Saenz] (UNC)<br />
|''[[Applied/ACMS/absF19#Pedro Saenz (UNC)|canceled]]''<br />
| Spagnolie<br />
|-<br />
|}<br />
<br />
== Future semesters ==<br />
<br />
<br />
<br />
<br />
----<br />
<br />
== Archived semesters ==<br />
<br />
*[[Applied/ACMS/Spring2020|Spring 2020]]<br />
*[[Applied/ACMS/Fall2019|Fall 2019]]<br />
*[[Applied/ACMS/Spring2019|Spring 2019]]<br />
*[[Applied/ACMS/Fall2018|Fall 2018]]<br />
*[[Applied/ACMS/Spring2018|Spring 2018]]<br />
*[[Applied/ACMS/Fall2017|Fall 2017]]<br />
*[[Applied/ACMS/Spring2017|Spring 2017]]<br />
*[[Applied/ACMS/Fall2016|Fall 2016]]<br />
*[[Applied/ACMS/Spring2016|Spring 2016]]<br />
*[[Applied/ACMS/Fall2015|Fall 2015]]<br />
*[[Applied/ACMS/Spring2015|Spring 2015]]<br />
*[[Applied/ACMS/Fall2014|Fall 2014]]<br />
*[[Applied/ACMS/Spring2014|Spring 2014]]<br />
*[[Applied/ACMS/Fall2013|Fall 2013]]<br />
*[[Applied/ACMS/Spring2013|Spring 2013]]<br />
*[[Applied/ACMS/Fall2012|Fall 2012]]<br />
*[[Applied/ACMS/Spring2012|Spring 2012]]<br />
*[[Applied/ACMS/Fall2011|Fall 2011]]<br />
*[[Applied/ACMS/Spring2011|Spring 2011]]<br />
*[[Applied/ACMS/Fall2010|Fall 2010]]<br />
<!--<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring10.html Spring 2010]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall09.html Fall 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring09.html Spring 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall08.html Fall 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring08.html Spring 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall07.html Fall 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring07.html Spring 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall06.html Fall 2006]<br />
--><br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS&diff=19425Applied/ACMS2020-06-08T15:30:48Z<p>Spagnolie: /* Archived semesters */</p>
<hr />
<div>__NOTOC__<br />
<br />
= Applied and Computational Mathematics Seminar =<br />
<br />
*'''When:''' Fridays at 2:25pm (except as otherwise indicated)<br />
*'''Where:''' 901 Van Vleck Hall<br />
*'''Organizers:''' [http://www.math.wisc.edu/~qinli/ Qin Li], [http://www.math.wisc.edu/~spagnolie/ Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''To join the ACMS mailing list:''' See [https://admin.lists.wisc.edu/index.php?p=11&l=acms mailing list] website.<br />
<br />
<br><br />
<br />
<br />
== Spring 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
| Jan 31<br />
|[https://www.math.wisc.edu/~hung/ Hung Tran] (UW-Madison)<br />
|''[[Applied/ACMS/absS20#Hung Tran (UW-Madison)| Coagulation-Fragmentation equations with multiplicative coagulation kernel and constant fragmentation kernel]]''<br />
| Li<br />
|-<br />
| Feb 7<br />
|[https://www.usna.edu/Users/weaprcon/avramov/index.php Svetlana Avramov-Zamurovic] (United States Naval Academy)<br />
|''[[Applied/ACMS/absS20#Svetlana Avramov-Zamurovic (United States Naval Academy)|Experiments with Structured Light]]''<br />
| Stechmann<br />
|-<br />
| Feb 14<br />
|[http://math.mit.edu/~vadicgor/ Vadim Gorin] (UW-Madison)<br />
|''[[Applied/ACMS/absS20#Vadim Gorin (UW-Madison)| Integrability of KPZ equation]]''<br />
| Li<br />
|-<br />
| Feb 21<br />
|[http://www.personal.psu.edu/jzh13/ John Harlim] (Penn State University)<br />
|''[[Applied/ACMS/absS20#Speaker (Penn State University)|Modeling Dynamical Systems with Machine Learning]]''<br />
| Chen<br />
|-<br />
| Feb 28<br />
|[https://cims.nyu.edu/~yangq/ Qiu Yang] (NYU/UVic/NCAR)<br />
|''[[Applied/ACMS/absS20#Speaker (NYU/UVic/NCAR)|Upscale Impact of Mesoscale Convective Systems on the MJO and Its Parameterization in Coarse-Resolution GCMs]]''<br />
| Chen<br />
|-<br />
| Mar 6<br />
|[https://directory.engr.wisc.edu/ep/Faculty/Bronkhorst_Curt/ Curt Bronkhorst] (UW-Madison Engineering Physics)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|Computational Prediction of Shear Banding and Deformation Twinning in Metals]]''<br />
| Smith<br />
|-<br />
| Mar 13<br />
|[http://www.columbia.edu/~ktm2132/ Kyle Mandli] (Columbia)<br />
|''[[Applied/ACMS/absS20#Kyle Mandli (Columbia)|canceled]]''<br />
| Wally<br />
|-<br />
| Mar 20<br />
|[Spring break] (Spring Break!)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|title]]''<br />
| host<br />
|-<br />
| Mar 27<br />
|[http://www-personal.umich.edu/~jcsch/ John Schotland] (U Mich)<br />
|''[[Applied/ACMS/absS20#John Schotland (Michigan)|canceled]]''<br />
| host<br />
|-<br />
| Apr 3<br />
|[http://keaton-burns.com/ Keaton Burns] (MIT)<br />
|''[[Applied/ACMS/absS20#Keaton Burns (MIT)| Flexible spectral methods and high-level programming for PDEs]]'' <br />
(Virtual, link to recording [https://www.math.wisc.edu/~appliedmathlab/Seminars/ACMS_040220_Burns.mp4 here])<br />
| Spagnolie<br />
|-<br />
| Apr 10<br />
|[https://www.princeton.edu/~lecoanet/ Daniel Lecoanet] (Princeton)<br />
|''[[Applied/ACMS/absS20#Daniel Lecoanet (Princeton)|canceled]]''<br />
| Wally<br />
|-<br />
| Apr 17<br />
|[https://www.ornl.gov/staff-profile/hoang-tran Hoang Tran] (Oak Ridge National Laboratory)<br />
|''[[Applied/ACMS/absS20#Hoang Tran (institution)|canceled]]''<br />
| Tran<br />
|-<br />
| Apr 24<br />
|[https://www.pml.unc.edu/ Pedro Saenz] (UNC)<br />
|''[[Applied/ACMS/absF19#Pedro Saenz (UNC)|canceled]]''<br />
| Spagnolie<br />
|-<br />
|}<br />
<br />
== Future semesters ==<br />
<br />
<br />
<br />
<br />
----<br />
<br />
== Archived semesters ==<br />
<br />
*[[Applied/ACMS/Fall2020|Fall 2020]]<br />
*[[Applied/ACMS/Spring2020|Spring 2020]]<br />
*[[Applied/ACMS/Fall2019|Fall 2019]]<br />
*[[Applied/ACMS/Spring2019|Spring 2019]]<br />
*[[Applied/ACMS/Fall2018|Fall 2018]]<br />
*[[Applied/ACMS/Spring2018|Spring 2018]]<br />
*[[Applied/ACMS/Fall2017|Fall 2017]]<br />
*[[Applied/ACMS/Spring2017|Spring 2017]]<br />
*[[Applied/ACMS/Fall2016|Fall 2016]]<br />
*[[Applied/ACMS/Spring2016|Spring 2016]]<br />
*[[Applied/ACMS/Fall2015|Fall 2015]]<br />
*[[Applied/ACMS/Spring2015|Spring 2015]]<br />
*[[Applied/ACMS/Fall2014|Fall 2014]]<br />
*[[Applied/ACMS/Spring2014|Spring 2014]]<br />
*[[Applied/ACMS/Fall2013|Fall 2013]]<br />
*[[Applied/ACMS/Spring2013|Spring 2013]]<br />
*[[Applied/ACMS/Fall2012|Fall 2012]]<br />
*[[Applied/ACMS/Spring2012|Spring 2012]]<br />
*[[Applied/ACMS/Fall2011|Fall 2011]]<br />
*[[Applied/ACMS/Spring2011|Spring 2011]]<br />
*[[Applied/ACMS/Fall2010|Fall 2010]]<br />
<!--<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring10.html Spring 2010]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall09.html Fall 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring09.html Spring 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall08.html Fall 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring08.html Spring 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall07.html Fall 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring07.html Spring 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall06.html Fall 2006]<br />
--><br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS&diff=19336Applied/ACMS2020-04-07T15:43:43Z<p>Spagnolie: /* Spring 2020 */</p>
<hr />
<div>__NOTOC__<br />
<br />
= Applied and Computational Mathematics Seminar =<br />
<br />
*'''When:''' Fridays at 2:25pm (except as otherwise indicated)<br />
*'''Where:''' 901 Van Vleck Hall<br />
*'''Organizers:''' [http://www.math.wisc.edu/~qinli/ Qin Li], [http://www.math.wisc.edu/~spagnolie/ Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''To join the ACMS mailing list:''' See [https://admin.lists.wisc.edu/index.php?p=11&l=acms mailing list] website.<br />
<br />
<br><br />
<br />
<br />
== Spring 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
| Jan 31<br />
|[https://www.math.wisc.edu/~hung/ Hung Tran] (UW-Madison)<br />
|''[[Applied/ACMS/absS20#Hung Tran (UW-Madison)| Coagulation-Fragmentation equations with multiplicative coagulation kernel and constant fragmentation kernel]]''<br />
| Li<br />
|-<br />
| Feb 7<br />
|[https://www.usna.edu/Users/weaprcon/avramov/index.php Svetlana Avramov-Zamurovic] (United States Naval Academy)<br />
|''[[Applied/ACMS/absS20#Svetlana Avramov-Zamurovic (United States Naval Academy)|Experiments with Structured Light]]''<br />
| Stechmann<br />
|-<br />
| Feb 14<br />
|[http://math.mit.edu/~vadicgor/ Vadim Gorin] (UW-Madison)<br />
|''[[Applied/ACMS/absS20#Vadim Gorin (UW-Madison)| Integrability of KPZ equation]]''<br />
| Li<br />
|-<br />
| Feb 21<br />
|[http://www.personal.psu.edu/jzh13/ John Harlim] (Penn State University)<br />
|''[[Applied/ACMS/absS20#Speaker (Penn State University)|Modeling Dynamical Systems with Machine Learning]]''<br />
| Chen<br />
|-<br />
| Feb 28<br />
|[https://cims.nyu.edu/~yangq/ Qiu Yang] (NYU/UVic/NCAR)<br />
|''[[Applied/ACMS/absS20#Speaker (NYU/UVic/NCAR)|Upscale Impact of Mesoscale Convective Systems on the MJO and Its Parameterization in Coarse-Resolution GCMs]]''<br />
| Chen<br />
|-<br />
| Mar 6<br />
|[https://directory.engr.wisc.edu/ep/Faculty/Bronkhorst_Curt/ Curt Bronkhorst] (UW-Madison Engineering Physics)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|Computational Prediction of Shear Banding and Deformation Twinning in Metals]]''<br />
| Smith<br />
|-<br />
| Mar 13<br />
|[http://www.columbia.edu/~ktm2132/ Kyle Mandli] (Columbia)<br />
|''[[Applied/ACMS/absS20#Kyle Mandli (Columbia)|canceled]]''<br />
| Wally<br />
|-<br />
| Mar 20<br />
|[Spring break] (Spring Break!)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|title]]''<br />
| host<br />
|-<br />
| Mar 27<br />
|[http://www-personal.umich.edu/~jcsch/ John Schotland] (U Mich)<br />
|''[[Applied/ACMS/absS20#John Schotland (Michigan)|canceled]]''<br />
| host<br />
|-<br />
| Apr 3<br />
|[http://keaton-burns.com/ Keaton Burns] (MIT)<br />
|''[[Applied/ACMS/absS20#Keaton Burns (MIT)| Flexible spectral methods and high-level programming for PDEs]]'' <br />
(Virtual, link to recording [https://www.math.wisc.edu/~appliedmathlab/Seminars/ACMS_040220_Burns.mp4 here])<br />
| Spagnolie<br />
|-<br />
| Apr 10<br />
|[https://www.princeton.edu/~lecoanet/ Daniel Lecoanet] (Princeton)<br />
|''[[Applied/ACMS/absS20#Daniel Lecoanet (Princeton)|canceled]]''<br />
| Wally<br />
|-<br />
| Apr 17<br />
|[https://www.ornl.gov/staff-profile/hoang-tran Hoang Tran] (Oak Ridge National Laboratory)<br />
|''[[Applied/ACMS/absS20#Hoang Tran (institution)|canceled]]''<br />
| Tran<br />
|-<br />
| Apr 24<br />
|[https://www.pml.unc.edu/ Pedro Saenz] (UNC)<br />
|''[[Applied/ACMS/absF19#Pedro Saenz (UNC)|canceled]]''<br />
| Spagnolie<br />
|-<br />
|}<br />
<br />
== Future semesters ==<br />
<br />
<br />
<br />
<br />
----<br />
<br />
== Archived semesters ==<br />
<br />
*[[Applied/ACMS/Spring2020|Spring 2020]]<br />
*[[Applied/ACMS/Fall2019|Fall 2019]]<br />
*[[Applied/ACMS/Spring2019|Spring 2019]]<br />
*[[Applied/ACMS/Fall2018|Fall 2018]]<br />
*[[Applied/ACMS/Spring2018|Spring 2018]]<br />
*[[Applied/ACMS/Fall2017|Fall 2017]]<br />
*[[Applied/ACMS/Spring2017|Spring 2017]]<br />
*[[Applied/ACMS/Fall2016|Fall 2016]]<br />
*[[Applied/ACMS/Spring2016|Spring 2016]]<br />
*[[Applied/ACMS/Fall2015|Fall 2015]]<br />
*[[Applied/ACMS/Spring2015|Spring 2015]]<br />
*[[Applied/ACMS/Fall2014|Fall 2014]]<br />
*[[Applied/ACMS/Spring2014|Spring 2014]]<br />
*[[Applied/ACMS/Fall2013|Fall 2013]]<br />
*[[Applied/ACMS/Spring2013|Spring 2013]]<br />
*[[Applied/ACMS/Fall2012|Fall 2012]]<br />
*[[Applied/ACMS/Spring2012|Spring 2012]]<br />
*[[Applied/ACMS/Fall2011|Fall 2011]]<br />
*[[Applied/ACMS/Spring2011|Spring 2011]]<br />
*[[Applied/ACMS/Fall2010|Fall 2010]]<br />
<!--<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring10.html Spring 2010]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall09.html Fall 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring09.html Spring 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall08.html Fall 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring08.html Spring 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall07.html Fall 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring07.html Spring 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall06.html Fall 2006]<br />
--><br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS&diff=19333Applied/ACMS2020-04-07T14:48:45Z<p>Spagnolie: /* Spring 2020 */</p>
<hr />
<div>__NOTOC__<br />
<br />
= Applied and Computational Mathematics Seminar =<br />
<br />
*'''When:''' Fridays at 2:25pm (except as otherwise indicated)<br />
*'''Where:''' 901 Van Vleck Hall<br />
*'''Organizers:''' [http://www.math.wisc.edu/~qinli/ Qin Li], [http://www.math.wisc.edu/~spagnolie/ Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''To join the ACMS mailing list:''' See [https://admin.lists.wisc.edu/index.php?p=11&l=acms mailing list] website.<br />
<br />
<br><br />
<br />
<br />
== Spring 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
| Jan 31<br />
|[https://www.math.wisc.edu/~hung/ Hung Tran] (UW-Madison)<br />
|''[[Applied/ACMS/absS20#Hung Tran (UW-Madison)| Coagulation-Fragmentation equations with multiplicative coagulation kernel and constant fragmentation kernel]]''<br />
| Li<br />
|-<br />
| Feb 7<br />
|[https://www.usna.edu/Users/weaprcon/avramov/index.php Svetlana Avramov-Zamurovic] (United States Naval Academy)<br />
|''[[Applied/ACMS/absS20#Svetlana Avramov-Zamurovic (United States Naval Academy)|Experiments with Structured Light]]''<br />
| Stechmann<br />
|-<br />
| Feb 14<br />
|[http://math.mit.edu/~vadicgor/ Vadim Gorin] (UW-Madison)<br />
|''[[Applied/ACMS/absS20#Vadim Gorin (UW-Madison)| Integrability of KPZ equation]]''<br />
| Li<br />
|-<br />
| Feb 21<br />
|[http://www.personal.psu.edu/jzh13/ John Harlim] (Penn State University)<br />
|''[[Applied/ACMS/absS20#Speaker (Penn State University)|Modeling Dynamical Systems with Machine Learning]]''<br />
| Chen<br />
|-<br />
| Feb 28<br />
|[https://cims.nyu.edu/~yangq/ Qiu Yang] (NYU/UVic/NCAR)<br />
|''[[Applied/ACMS/absS20#Speaker (NYU/UVic/NCAR)|Upscale Impact of Mesoscale Convective Systems on the MJO and Its Parameterization in Coarse-Resolution GCMs]]''<br />
| Chen<br />
|-<br />
| Mar 6<br />
|[https://directory.engr.wisc.edu/ep/Faculty/Bronkhorst_Curt/ Curt Bronkhorst] (UW-Madison Engineering Physics)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|Computational Prediction of Shear Banding and Deformation Twinning in Metals]]''<br />
| Smith<br />
|-<br />
| Mar 13<br />
|[http://www.columbia.edu/~ktm2132/ Kyle Mandli] (Columbia)<br />
|''[[Applied/ACMS/absS20#Kyle Mandli (Columbia)|canceled]]''<br />
| Wally<br />
|-<br />
| Mar 20<br />
|[Spring break] (Spring Break!)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|title]]''<br />
| host<br />
|-<br />
| Mar 27<br />
|[http://www-personal.umich.edu/~jcsch/ John Schotland] (U Mich)<br />
|''[[Applied/ACMS/absS20#John Schotland (Michigan)|canceled]]''<br />
| host<br />
|-<br />
| Apr 3<br />
|[http://keaton-burns.com/ Keaton Burns] (MIT)<br />
|''[[Applied/ACMS/absS20#Keaton Burns (MIT)| Flexible spectral methods and high-level programming for PDEs]]'' <br />
(Virtual, link to recording [https://www.math.wisc.edu/~spagnolie/Seminars/ACMS_040220_Burns.mp4 here])<br />
| Spagnolie<br />
|-<br />
| Apr 10<br />
|[https://www.princeton.edu/~lecoanet/ Daniel Lecoanet] (Princeton)<br />
|''[[Applied/ACMS/absS20#Daniel Lecoanet (Princeton)|canceled]]''<br />
| Wally<br />
|-<br />
| Apr 17<br />
|[https://www.ornl.gov/staff-profile/hoang-tran Hoang Tran] (Oak Ridge National Laboratory)<br />
|''[[Applied/ACMS/absS20#Hoang Tran (institution)|canceled]]''<br />
| Tran<br />
|-<br />
| Apr 24<br />
|[https://www.pml.unc.edu/ Pedro Saenz] (UNC)<br />
|''[[Applied/ACMS/absF19#Pedro Saenz (UNC)|canceled]]''<br />
| Spagnolie<br />
|-<br />
|}<br />
<br />
== Future semesters ==<br />
<br />
<br />
<br />
<br />
----<br />
<br />
== Archived semesters ==<br />
<br />
*[[Applied/ACMS/Spring2020|Spring 2020]]<br />
*[[Applied/ACMS/Fall2019|Fall 2019]]<br />
*[[Applied/ACMS/Spring2019|Spring 2019]]<br />
*[[Applied/ACMS/Fall2018|Fall 2018]]<br />
*[[Applied/ACMS/Spring2018|Spring 2018]]<br />
*[[Applied/ACMS/Fall2017|Fall 2017]]<br />
*[[Applied/ACMS/Spring2017|Spring 2017]]<br />
*[[Applied/ACMS/Fall2016|Fall 2016]]<br />
*[[Applied/ACMS/Spring2016|Spring 2016]]<br />
*[[Applied/ACMS/Fall2015|Fall 2015]]<br />
*[[Applied/ACMS/Spring2015|Spring 2015]]<br />
*[[Applied/ACMS/Fall2014|Fall 2014]]<br />
*[[Applied/ACMS/Spring2014|Spring 2014]]<br />
*[[Applied/ACMS/Fall2013|Fall 2013]]<br />
*[[Applied/ACMS/Spring2013|Spring 2013]]<br />
*[[Applied/ACMS/Fall2012|Fall 2012]]<br />
*[[Applied/ACMS/Spring2012|Spring 2012]]<br />
*[[Applied/ACMS/Fall2011|Fall 2011]]<br />
*[[Applied/ACMS/Spring2011|Spring 2011]]<br />
*[[Applied/ACMS/Fall2010|Fall 2010]]<br />
<!--<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring10.html Spring 2010]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall09.html Fall 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring09.html Spring 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall08.html Fall 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring08.html Spring 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall07.html Fall 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring07.html Spring 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall06.html Fall 2006]<br />
--><br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS/absS20&diff=19329Applied/ACMS/absS202020-04-02T15:43:21Z<p>Spagnolie: /* Keaton Burns (MIT) */</p>
<hr />
<div>= ACMS Abstracts: Spring 2020 =<br />
<br />
=== Hung Tran ===<br />
<br />
Title: Coagulation-Fragmentation equations with multiplicative coagulation kernel and constant fragmentation kernel<br />
<br />
Abstract: We study a critical case of Coagulation-Fragmentation equations with multiplicative coagulation kernel and constant fragmentation kernel. Our method is based on the study of viscosity solutions to a new singular Hamilton-Jacobi equation, which results from applying the Bernstein transform to the original Coagulation-Fragmentation equation. Our results include wellposedness, regularity and long-time behaviors of viscosity solutions to the Hamilton-Jacobi equation in certain regimes, which have implications to wellposedness and long-time behaviors of mass-conserving solutions to the Coagulation-Fragmentation equation. Joint work with Truong-Son Van (CMU).<br />
<br />
=== Svetlana Avramov-Zamurovic ===<br />
<br />
Title: Experiments with Structured Light<br />
<br />
Abstract: Complete understanding of laser light propagation through random complex media, including theoretical models and experimental verifications, is relevant for numerous contemporary communication and sensors applications. Light radiation is the most suitable for transmitting high data rates due to its wide bandwidth, but it is significantly impacted by the state of the propagation media. To mitigate the deterioration of laser light along a propagation path, various independent characteristics of light could be manipulated, most notably: spatial coherence, intensity, wavelength, polarization, as well as the orbital angular momentum of light. Much of the research has focused on laser propagation through turbulent atmospheric conditions, but with the development of distributed sensor networks and autonomous underwater vehicles, achieving high performance data transmission in the ocean is becoming exceptionally valuable. The propagation of laser light in water is influenced by high attenuation rates caused by scattering from organic and inorganic particulates as well as change in refractive index due to temperature and salinity fluctuations. Structured light offers a tool to combat some of the mentioned deteriorations.<br />
<br />
The talk will focus on experiments with structured light propagating in maritime environment. First, the underwater communication system that uses the superposition of coherent beams carrying orbital angular momentum, will be presented. The design objective is the creation of a family of dissimilar images suitable for fast and accurate classification using only the intensity patterns imaged by a camera. Next, the measurements from the field experiments with spatially partially coherent light as well as polarization diversity, propagating at the Academy grounds, will be given. The talk emphasis will be on the physical aspects of the experiments with structured laser light, and the relationship to the data obtained.<br />
<br />
=== Vadim Gorin ===<br />
<br />
Title: Integrability of KPZ equation.<br />
<br />
Abstract: Kardar-Parisi-Zhang stochastic partial differential equation is a prototypical model for the random growth of one-dimensional interfaces. I will review how it appeared and present various exact formulas, which allow the large time asymptotic analysis of the solutions to the equation and hint on its connections to other stochastic objects.<br />
<br />
=== John Harlim ===<br />
<br />
Title: Modeling Dynamical Systems with Machine Learning<br />
<br />
Abstract: The recent success of machine learning has drawn tremendous interest in applied mathematics and scientific computations. In the first part of the talk, I will discuss recent efforts in using an unsupervised learning algorithm (a branch of machine learning) to estimate time-dependent densities of Ito diffusion from time series of the stochastic processes. The second part of the talk is on the topic of model error arises in modeling of dynamical systems. Particularly, I will discuss a general framework to compensate for the model error. The proposed framework reformulates the model error problem into a supervised learning task to approximate a very high-dimensional target function involving the Mori-Zwanzig representation of projected dynamical systems. Connection to traditional parametric approaches will be clarified as specifying the appropriate hypothesis space for the target function. Theoretical convergence and numerical demonstration on modeling problems arising from PDE's will be discussed.<br />
<br />
=== Qiu Yang ===<br />
<br />
Title: Upscale Impact of Mesoscale Convective Systems on the MJO and Its Parameterization in Coarse-Resolution GCMs<br />
<br />
Abstract: The multi-scale organization of tropical convection has emerged as an exciting interdisciplinary research area where many applied math methods can be used to address real-world problems. For example, Madden-Julian oscillation (MJO), the holy grail of tropical atmospheric dynamics, is organized in a hierarchical structure that the eastward-moving planetary-scale envelope usually contains multiple synoptic-scale superclusters with numerous embedded mesoscale convective systems (MCSs). Present-day global climate models (GCMs) fail to explicitly resolve small-scale MCSs due to their coarse resolutions. We hypothesized that such inadequate treatment of MCSs and their upscale impact leads to the poorly simulated MJOs in the GCMs. Here we tackled this challenging problem from three different perspectives based on models in a hierarchy of complexity. We first simulated the multi-scale organization of tropical convection in a 2D global cloud-resolving model and demonstrated the crucial upscale impact of MCSs on the MJO through energy budget analysis. Then we used a multi-scale theoretical model to describe the observed scenario where a convectively coupled Kelvin wave on the synoptic-scale typically contains numerous embedded MCSs. The eddy transfer of momentum and temperature that stands out from the model is interpreted as the upscale impact of MCSs on large-scale circulation. Finally, we developed a basic parameterization for the upscale impact of MCSs based on the multi-scale theoretical model. We tested the effect of this parameterization in both an idealized testbed and a coarse-resolution GCM. The results show that the parameterization promotes persistent eastward propagation of the MJO and recover its realistic features of spatiotemporal variability. <br />
<br />
=== Curt A. Bronkhorst ===<br />
<br />
Title: Computational Prediction of Shear Banding and Deformation Twinning in Metals<br />
<br />
Abstract: The high deformation rate mechanical loading of polycrystalline metallic materials, which have ready access to plastic deformation mechanisms, generally involve an intense process of several deformation mechanisms within the material: dislocation slip (thermally activated and phonon drag dominated), recovery (annihilation and recrystallization), mechanical twinning, porosity, and shear banding depending upon the material. For this class of ductile materials, depending upon the boundary conditions imposed, there are varying degrees of porosity or adiabatic shear banding taking place at the later stages of the deformation history. Each of these two processes are as yet a significant challenge to predict accurately. This is true for both material models to represent the physical response of the material or the computational framework to represent accurately the creation of new surfaces or interfaces in a topologically independent way. Within this talk, I will present an enriched element technique to represent the adiabatic shear banding and deformation twinning process within a traditional Lagrangian finite element framework. A rate-dependent onset criterion for the initiation of a band is defined based upon a rate and temperature dependent material model. Once the bifurcation condition is met, the location and orientation of an embedded field zone is computed and inserted within a computational element. Once embedded the boundary conditions between the localized and unlocalized regions of the element are enforced and the composite sub-grid element follows a weighted average representation of both regions. Continuity in shear band growth is ensured by employing a non-local level-set technique connected to the displacement field within the finite-element solver. The material inside the band is able to be represented independent from the outside material and the thickness of the band can be assigned by any appropriate method. Dynamic recrystallization (DRX) is often observed in conjunction with adiabatic shear banding (ASB) in polycrystalline materials and is believed to be a critical softening mechanism contributing to the material instability. The recrystallized nanograins in the shear band have few dislocations compared to the material outside of the shear band. We reformulate a recently developed continuum theory of polycrystalline plasticity and include the creation of grain boundaries. While the shear-banding instability emerges because thermal heating is faster than heat dissipation, recrystallization is interpreted as an entropic effect arising from the competition between dislocation creation and grain boundary formation and is a significant softening mechanism. We show that our theory closely matches recent results in sheared 316L stainless steel. The theory thus provides a thermodynamically consistent way to systematically describe the formation of shear bands and recrystallized grains therein. The numerical tool has recently been applied to the modeling of deformation twinning in high-purity Ti which will be briefly discussed.<br />
<br />
=== Keaton Burns (MIT) ===<br />
<br />
Title: Flexible spectral methods and high-level programming for PDEs (Virtual!)<br />
<br />
Abstract: The large-scale numerical solution of PDEs is an essential part of scientific research. Decades of work have been put into developing fast numerical schemes for specific equations, but computational research in many fields is still largely software-limited. Here I will discuss how algorithmic flexibility and composability can enable new science, as illustrated by the Dedalus Project. Dedalus is an open-source Python framework that automates the solution of general PDEs using spectral methods. High-level abstractions allow users to symbolically specify equations, parallelize and scale their solvers to thousands of cores, and perform arbitrary analysis with the computed solutions. I will provide an overview the code’s design and the underlying sparse spectral algorithms, and show how they are enabling novel simulations of diverse hydrodynamical systems. I will include astrophysical and geophysical applications using new bases for tensor-valued equations in spherical domains, immersed boundary methods for multiphase flows, and multi-domain simulations interfacing Dedalus with other PDE and integral equation solvers.</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS&diff=19328Applied/ACMS2020-04-02T15:27:26Z<p>Spagnolie: /* Spring 2020 */</p>
<hr />
<div>__NOTOC__<br />
<br />
= Applied and Computational Mathematics Seminar =<br />
<br />
*'''When:''' Fridays at 2:25pm (except as otherwise indicated)<br />
*'''Where:''' 901 Van Vleck Hall<br />
*'''Organizers:''' [http://www.math.wisc.edu/~qinli/ Qin Li], [http://www.math.wisc.edu/~spagnolie/ Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''To join the ACMS mailing list:''' See [https://admin.lists.wisc.edu/index.php?p=11&l=acms mailing list] website.<br />
<br />
<br><br />
<br />
<br />
== Spring 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
| Jan 31<br />
|[https://www.math.wisc.edu/~hung/ Hung Tran] (UW-Madison)<br />
|''[[Applied/ACMS/absS20#Hung Tran (UW-Madison)| Coagulation-Fragmentation equations with multiplicative coagulation kernel and constant fragmentation kernel]]''<br />
| Li<br />
|-<br />
| Feb 7<br />
|[https://www.usna.edu/Users/weaprcon/avramov/index.php Svetlana Avramov-Zamurovic] (United States Naval Academy)<br />
|''[[Applied/ACMS/absS20#Svetlana Avramov-Zamurovic (United States Naval Academy)|Experiments with Structured Light]]''<br />
| Stechmann<br />
|-<br />
| Feb 14<br />
|[http://math.mit.edu/~vadicgor/ Vadim Gorin] (UW-Madison)<br />
|''[[Applied/ACMS/absS20#Vadim Gorin (UW-Madison)| Integrability of KPZ equation]]''<br />
| Li<br />
|-<br />
| Feb 21<br />
|[http://www.personal.psu.edu/jzh13/ John Harlim] (Penn State University)<br />
|''[[Applied/ACMS/absS20#Speaker (Penn State University)|Modeling Dynamical Systems with Machine Learning]]''<br />
| Chen<br />
|-<br />
| Feb 28<br />
|[https://cims.nyu.edu/~yangq/ Qiu Yang] (NYU/UVic/NCAR)<br />
|''[[Applied/ACMS/absS20#Speaker (NYU/UVic/NCAR)|Upscale Impact of Mesoscale Convective Systems on the MJO and Its Parameterization in Coarse-Resolution GCMs]]''<br />
| Chen<br />
|-<br />
| Mar 6<br />
|[https://directory.engr.wisc.edu/ep/Faculty/Bronkhorst_Curt/ Curt Bronkhorst] (UW-Madison Engineering Physics)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|Computational Prediction of Shear Banding and Deformation Twinning in Metals]]''<br />
| Smith<br />
|-<br />
| Mar 13<br />
|[http://www.columbia.edu/~ktm2132/ Kyle Mandli] (Columbia)<br />
|''[[Applied/ACMS/absS20#Kyle Mandli (Columbia)|canceled]]''<br />
| Wally<br />
|-<br />
| Mar 20<br />
|[Spring break] (Spring Break!)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|title]]''<br />
| host<br />
|-<br />
| Mar 27<br />
|[http://www-personal.umich.edu/~jcsch/ John Schotland] (U Mich)<br />
|''[[Applied/ACMS/absS20#John Schotland (Michigan)|canceled]]''<br />
| host<br />
|-<br />
| Apr 3<br />
|[http://keaton-burns.com/ Keaton Burns] (MIT)<br />
|''[[Applied/ACMS/absS20#Keaton Burns (MIT)| Flexible spectral methods and high-level programming for PDEs (Virtual, on Webex!) ]]''<br />
| Spagnolie<br />
|-<br />
| Apr 10<br />
|[https://www.princeton.edu/~lecoanet/ Daniel Lecoanet] (Princeton)<br />
|''[[Applied/ACMS/absS20#Daniel Lecoanet (Princeton)|canceled]]''<br />
| Wally<br />
|-<br />
| Apr 17<br />
|[https://www.ornl.gov/staff-profile/hoang-tran Hoang Tran] (Oak Ridge National Laboratory)<br />
|''[[Applied/ACMS/absS20#Hoang Tran (institution)|canceled]]''<br />
| Tran<br />
|-<br />
| Apr 24<br />
|[https://www.pml.unc.edu/ Pedro Saenz] (UNC)<br />
|''[[Applied/ACMS/absF19#Pedro Saenz (UNC)|canceled]]''<br />
| Spagnolie<br />
|-<br />
|}<br />
<br />
== Future semesters ==<br />
<br />
<br />
<br />
<br />
----<br />
<br />
== Archived semesters ==<br />
<br />
*[[Applied/ACMS/Spring2020|Spring 2020]]<br />
*[[Applied/ACMS/Fall2019|Fall 2019]]<br />
*[[Applied/ACMS/Spring2019|Spring 2019]]<br />
*[[Applied/ACMS/Fall2018|Fall 2018]]<br />
*[[Applied/ACMS/Spring2018|Spring 2018]]<br />
*[[Applied/ACMS/Fall2017|Fall 2017]]<br />
*[[Applied/ACMS/Spring2017|Spring 2017]]<br />
*[[Applied/ACMS/Fall2016|Fall 2016]]<br />
*[[Applied/ACMS/Spring2016|Spring 2016]]<br />
*[[Applied/ACMS/Fall2015|Fall 2015]]<br />
*[[Applied/ACMS/Spring2015|Spring 2015]]<br />
*[[Applied/ACMS/Fall2014|Fall 2014]]<br />
*[[Applied/ACMS/Spring2014|Spring 2014]]<br />
*[[Applied/ACMS/Fall2013|Fall 2013]]<br />
*[[Applied/ACMS/Spring2013|Spring 2013]]<br />
*[[Applied/ACMS/Fall2012|Fall 2012]]<br />
*[[Applied/ACMS/Spring2012|Spring 2012]]<br />
*[[Applied/ACMS/Fall2011|Fall 2011]]<br />
*[[Applied/ACMS/Spring2011|Spring 2011]]<br />
*[[Applied/ACMS/Fall2010|Fall 2010]]<br />
<!--<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring10.html Spring 2010]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall09.html Fall 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring09.html Spring 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall08.html Fall 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring08.html Spring 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall07.html Fall 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring07.html Spring 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall06.html Fall 2006]<br />
--><br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS/absS20&diff=19323Applied/ACMS/absS202020-04-01T22:25:17Z<p>Spagnolie: /* Keaton Burns (MIT) */</p>
<hr />
<div>= ACMS Abstracts: Spring 2020 =<br />
<br />
=== Hung Tran ===<br />
<br />
Title: Coagulation-Fragmentation equations with multiplicative coagulation kernel and constant fragmentation kernel<br />
<br />
Abstract: We study a critical case of Coagulation-Fragmentation equations with multiplicative coagulation kernel and constant fragmentation kernel. Our method is based on the study of viscosity solutions to a new singular Hamilton-Jacobi equation, which results from applying the Bernstein transform to the original Coagulation-Fragmentation equation. Our results include wellposedness, regularity and long-time behaviors of viscosity solutions to the Hamilton-Jacobi equation in certain regimes, which have implications to wellposedness and long-time behaviors of mass-conserving solutions to the Coagulation-Fragmentation equation. Joint work with Truong-Son Van (CMU).<br />
<br />
=== Svetlana Avramov-Zamurovic ===<br />
<br />
Title: Experiments with Structured Light<br />
<br />
Abstract: Complete understanding of laser light propagation through random complex media, including theoretical models and experimental verifications, is relevant for numerous contemporary communication and sensors applications. Light radiation is the most suitable for transmitting high data rates due to its wide bandwidth, but it is significantly impacted by the state of the propagation media. To mitigate the deterioration of laser light along a propagation path, various independent characteristics of light could be manipulated, most notably: spatial coherence, intensity, wavelength, polarization, as well as the orbital angular momentum of light. Much of the research has focused on laser propagation through turbulent atmospheric conditions, but with the development of distributed sensor networks and autonomous underwater vehicles, achieving high performance data transmission in the ocean is becoming exceptionally valuable. The propagation of laser light in water is influenced by high attenuation rates caused by scattering from organic and inorganic particulates as well as change in refractive index due to temperature and salinity fluctuations. Structured light offers a tool to combat some of the mentioned deteriorations.<br />
<br />
The talk will focus on experiments with structured light propagating in maritime environment. First, the underwater communication system that uses the superposition of coherent beams carrying orbital angular momentum, will be presented. The design objective is the creation of a family of dissimilar images suitable for fast and accurate classification using only the intensity patterns imaged by a camera. Next, the measurements from the field experiments with spatially partially coherent light as well as polarization diversity, propagating at the Academy grounds, will be given. The talk emphasis will be on the physical aspects of the experiments with structured laser light, and the relationship to the data obtained.<br />
<br />
=== Vadim Gorin ===<br />
<br />
Title: Integrability of KPZ equation.<br />
<br />
Abstract: Kardar-Parisi-Zhang stochastic partial differential equation is a prototypical model for the random growth of one-dimensional interfaces. I will review how it appeared and present various exact formulas, which allow the large time asymptotic analysis of the solutions to the equation and hint on its connections to other stochastic objects.<br />
<br />
=== John Harlim ===<br />
<br />
Title: Modeling Dynamical Systems with Machine Learning<br />
<br />
Abstract: The recent success of machine learning has drawn tremendous interest in applied mathematics and scientific computations. In the first part of the talk, I will discuss recent efforts in using an unsupervised learning algorithm (a branch of machine learning) to estimate time-dependent densities of Ito diffusion from time series of the stochastic processes. The second part of the talk is on the topic of model error arises in modeling of dynamical systems. Particularly, I will discuss a general framework to compensate for the model error. The proposed framework reformulates the model error problem into a supervised learning task to approximate a very high-dimensional target function involving the Mori-Zwanzig representation of projected dynamical systems. Connection to traditional parametric approaches will be clarified as specifying the appropriate hypothesis space for the target function. Theoretical convergence and numerical demonstration on modeling problems arising from PDE's will be discussed.<br />
<br />
=== Qiu Yang ===<br />
<br />
Title: Upscale Impact of Mesoscale Convective Systems on the MJO and Its Parameterization in Coarse-Resolution GCMs<br />
<br />
Abstract: The multi-scale organization of tropical convection has emerged as an exciting interdisciplinary research area where many applied math methods can be used to address real-world problems. For example, Madden-Julian oscillation (MJO), the holy grail of tropical atmospheric dynamics, is organized in a hierarchical structure that the eastward-moving planetary-scale envelope usually contains multiple synoptic-scale superclusters with numerous embedded mesoscale convective systems (MCSs). Present-day global climate models (GCMs) fail to explicitly resolve small-scale MCSs due to their coarse resolutions. We hypothesized that such inadequate treatment of MCSs and their upscale impact leads to the poorly simulated MJOs in the GCMs. Here we tackled this challenging problem from three different perspectives based on models in a hierarchy of complexity. We first simulated the multi-scale organization of tropical convection in a 2D global cloud-resolving model and demonstrated the crucial upscale impact of MCSs on the MJO through energy budget analysis. Then we used a multi-scale theoretical model to describe the observed scenario where a convectively coupled Kelvin wave on the synoptic-scale typically contains numerous embedded MCSs. The eddy transfer of momentum and temperature that stands out from the model is interpreted as the upscale impact of MCSs on large-scale circulation. Finally, we developed a basic parameterization for the upscale impact of MCSs based on the multi-scale theoretical model. We tested the effect of this parameterization in both an idealized testbed and a coarse-resolution GCM. The results show that the parameterization promotes persistent eastward propagation of the MJO and recover its realistic features of spatiotemporal variability. <br />
<br />
=== Curt A. Bronkhorst ===<br />
<br />
Title: Computational Prediction of Shear Banding and Deformation Twinning in Metals<br />
<br />
Abstract: The high deformation rate mechanical loading of polycrystalline metallic materials, which have ready access to plastic deformation mechanisms, generally involve an intense process of several deformation mechanisms within the material: dislocation slip (thermally activated and phonon drag dominated), recovery (annihilation and recrystallization), mechanical twinning, porosity, and shear banding depending upon the material. For this class of ductile materials, depending upon the boundary conditions imposed, there are varying degrees of porosity or adiabatic shear banding taking place at the later stages of the deformation history. Each of these two processes are as yet a significant challenge to predict accurately. This is true for both material models to represent the physical response of the material or the computational framework to represent accurately the creation of new surfaces or interfaces in a topologically independent way. Within this talk, I will present an enriched element technique to represent the adiabatic shear banding and deformation twinning process within a traditional Lagrangian finite element framework. A rate-dependent onset criterion for the initiation of a band is defined based upon a rate and temperature dependent material model. Once the bifurcation condition is met, the location and orientation of an embedded field zone is computed and inserted within a computational element. Once embedded the boundary conditions between the localized and unlocalized regions of the element are enforced and the composite sub-grid element follows a weighted average representation of both regions. Continuity in shear band growth is ensured by employing a non-local level-set technique connected to the displacement field within the finite-element solver. The material inside the band is able to be represented independent from the outside material and the thickness of the band can be assigned by any appropriate method. Dynamic recrystallization (DRX) is often observed in conjunction with adiabatic shear banding (ASB) in polycrystalline materials and is believed to be a critical softening mechanism contributing to the material instability. The recrystallized nanograins in the shear band have few dislocations compared to the material outside of the shear band. We reformulate a recently developed continuum theory of polycrystalline plasticity and include the creation of grain boundaries. While the shear-banding instability emerges because thermal heating is faster than heat dissipation, recrystallization is interpreted as an entropic effect arising from the competition between dislocation creation and grain boundary formation and is a significant softening mechanism. We show that our theory closely matches recent results in sheared 316L stainless steel. The theory thus provides a thermodynamically consistent way to systematically describe the formation of shear bands and recrystallized grains therein. The numerical tool has recently been applied to the modeling of deformation twinning in high-purity Ti which will be briefly discussed.<br />
<br />
=== Keaton Burns (MIT) ===<br />
<br />
Title: Flexible spectral methods and high-level programming for PDEs<br />
<br />
Abstract: The large-scale numerical solution of PDEs is an essential part of scientific research. Decades of work have been put into developing fast numerical schemes for specific equations, but computational research in many fields is still largely software-limited. Here I will discuss how algorithmic flexibility and composability can enable new science, as illustrated by the Dedalus Project. Dedalus is an open-source Python framework that automates the solution of general PDEs using spectral methods. High-level abstractions allow users to symbolically specify equations, parallelize and scale their solvers to thousands of cores, and perform arbitrary analysis with the computed solutions. I will provide an overview the code’s design and the underlying sparse spectral algorithms, and show how they are enabling novel simulations of diverse hydrodynamical systems. I will include astrophysical and geophysical applications using new bases for tensor-valued equations in spherical domains, immersed boundary methods for multiphase flows, and multi-domain simulations interfacing Dedalus with other PDE and integral equation solvers.</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS/absS20&diff=19322Applied/ACMS/absS202020-04-01T22:25:07Z<p>Spagnolie: /* ACMS Abstracts: Spring 2020 */</p>
<hr />
<div>= ACMS Abstracts: Spring 2020 =<br />
<br />
=== Hung Tran ===<br />
<br />
Title: Coagulation-Fragmentation equations with multiplicative coagulation kernel and constant fragmentation kernel<br />
<br />
Abstract: We study a critical case of Coagulation-Fragmentation equations with multiplicative coagulation kernel and constant fragmentation kernel. Our method is based on the study of viscosity solutions to a new singular Hamilton-Jacobi equation, which results from applying the Bernstein transform to the original Coagulation-Fragmentation equation. Our results include wellposedness, regularity and long-time behaviors of viscosity solutions to the Hamilton-Jacobi equation in certain regimes, which have implications to wellposedness and long-time behaviors of mass-conserving solutions to the Coagulation-Fragmentation equation. Joint work with Truong-Son Van (CMU).<br />
<br />
=== Svetlana Avramov-Zamurovic ===<br />
<br />
Title: Experiments with Structured Light<br />
<br />
Abstract: Complete understanding of laser light propagation through random complex media, including theoretical models and experimental verifications, is relevant for numerous contemporary communication and sensors applications. Light radiation is the most suitable for transmitting high data rates due to its wide bandwidth, but it is significantly impacted by the state of the propagation media. To mitigate the deterioration of laser light along a propagation path, various independent characteristics of light could be manipulated, most notably: spatial coherence, intensity, wavelength, polarization, as well as the orbital angular momentum of light. Much of the research has focused on laser propagation through turbulent atmospheric conditions, but with the development of distributed sensor networks and autonomous underwater vehicles, achieving high performance data transmission in the ocean is becoming exceptionally valuable. The propagation of laser light in water is influenced by high attenuation rates caused by scattering from organic and inorganic particulates as well as change in refractive index due to temperature and salinity fluctuations. Structured light offers a tool to combat some of the mentioned deteriorations.<br />
<br />
The talk will focus on experiments with structured light propagating in maritime environment. First, the underwater communication system that uses the superposition of coherent beams carrying orbital angular momentum, will be presented. The design objective is the creation of a family of dissimilar images suitable for fast and accurate classification using only the intensity patterns imaged by a camera. Next, the measurements from the field experiments with spatially partially coherent light as well as polarization diversity, propagating at the Academy grounds, will be given. The talk emphasis will be on the physical aspects of the experiments with structured laser light, and the relationship to the data obtained.<br />
<br />
=== Vadim Gorin ===<br />
<br />
Title: Integrability of KPZ equation.<br />
<br />
Abstract: Kardar-Parisi-Zhang stochastic partial differential equation is a prototypical model for the random growth of one-dimensional interfaces. I will review how it appeared and present various exact formulas, which allow the large time asymptotic analysis of the solutions to the equation and hint on its connections to other stochastic objects.<br />
<br />
=== John Harlim ===<br />
<br />
Title: Modeling Dynamical Systems with Machine Learning<br />
<br />
Abstract: The recent success of machine learning has drawn tremendous interest in applied mathematics and scientific computations. In the first part of the talk, I will discuss recent efforts in using an unsupervised learning algorithm (a branch of machine learning) to estimate time-dependent densities of Ito diffusion from time series of the stochastic processes. The second part of the talk is on the topic of model error arises in modeling of dynamical systems. Particularly, I will discuss a general framework to compensate for the model error. The proposed framework reformulates the model error problem into a supervised learning task to approximate a very high-dimensional target function involving the Mori-Zwanzig representation of projected dynamical systems. Connection to traditional parametric approaches will be clarified as specifying the appropriate hypothesis space for the target function. Theoretical convergence and numerical demonstration on modeling problems arising from PDE's will be discussed.<br />
<br />
=== Qiu Yang ===<br />
<br />
Title: Upscale Impact of Mesoscale Convective Systems on the MJO and Its Parameterization in Coarse-Resolution GCMs<br />
<br />
Abstract: The multi-scale organization of tropical convection has emerged as an exciting interdisciplinary research area where many applied math methods can be used to address real-world problems. For example, Madden-Julian oscillation (MJO), the holy grail of tropical atmospheric dynamics, is organized in a hierarchical structure that the eastward-moving planetary-scale envelope usually contains multiple synoptic-scale superclusters with numerous embedded mesoscale convective systems (MCSs). Present-day global climate models (GCMs) fail to explicitly resolve small-scale MCSs due to their coarse resolutions. We hypothesized that such inadequate treatment of MCSs and their upscale impact leads to the poorly simulated MJOs in the GCMs. Here we tackled this challenging problem from three different perspectives based on models in a hierarchy of complexity. We first simulated the multi-scale organization of tropical convection in a 2D global cloud-resolving model and demonstrated the crucial upscale impact of MCSs on the MJO through energy budget analysis. Then we used a multi-scale theoretical model to describe the observed scenario where a convectively coupled Kelvin wave on the synoptic-scale typically contains numerous embedded MCSs. The eddy transfer of momentum and temperature that stands out from the model is interpreted as the upscale impact of MCSs on large-scale circulation. Finally, we developed a basic parameterization for the upscale impact of MCSs based on the multi-scale theoretical model. We tested the effect of this parameterization in both an idealized testbed and a coarse-resolution GCM. The results show that the parameterization promotes persistent eastward propagation of the MJO and recover its realistic features of spatiotemporal variability. <br />
<br />
=== Curt A. Bronkhorst ===<br />
<br />
Title: Computational Prediction of Shear Banding and Deformation Twinning in Metals<br />
<br />
Abstract: The high deformation rate mechanical loading of polycrystalline metallic materials, which have ready access to plastic deformation mechanisms, generally involve an intense process of several deformation mechanisms within the material: dislocation slip (thermally activated and phonon drag dominated), recovery (annihilation and recrystallization), mechanical twinning, porosity, and shear banding depending upon the material. For this class of ductile materials, depending upon the boundary conditions imposed, there are varying degrees of porosity or adiabatic shear banding taking place at the later stages of the deformation history. Each of these two processes are as yet a significant challenge to predict accurately. This is true for both material models to represent the physical response of the material or the computational framework to represent accurately the creation of new surfaces or interfaces in a topologically independent way. Within this talk, I will present an enriched element technique to represent the adiabatic shear banding and deformation twinning process within a traditional Lagrangian finite element framework. A rate-dependent onset criterion for the initiation of a band is defined based upon a rate and temperature dependent material model. Once the bifurcation condition is met, the location and orientation of an embedded field zone is computed and inserted within a computational element. Once embedded the boundary conditions between the localized and unlocalized regions of the element are enforced and the composite sub-grid element follows a weighted average representation of both regions. Continuity in shear band growth is ensured by employing a non-local level-set technique connected to the displacement field within the finite-element solver. The material inside the band is able to be represented independent from the outside material and the thickness of the band can be assigned by any appropriate method. Dynamic recrystallization (DRX) is often observed in conjunction with adiabatic shear banding (ASB) in polycrystalline materials and is believed to be a critical softening mechanism contributing to the material instability. The recrystallized nanograins in the shear band have few dislocations compared to the material outside of the shear band. We reformulate a recently developed continuum theory of polycrystalline plasticity and include the creation of grain boundaries. While the shear-banding instability emerges because thermal heating is faster than heat dissipation, recrystallization is interpreted as an entropic effect arising from the competition between dislocation creation and grain boundary formation and is a significant softening mechanism. We show that our theory closely matches recent results in sheared 316L stainless steel. The theory thus provides a thermodynamically consistent way to systematically describe the formation of shear bands and recrystallized grains therein. The numerical tool has recently been applied to the modeling of deformation twinning in high-purity Ti which will be briefly discussed.<br />
<br />
=== Keaton Burns (MIT) ===<br />
<br />
Title: Flexible spectral methods and high-level programming for PDEs<br />
<br />
Abstract: Abstract: The large-scale numerical solution of PDEs is an essential part of scientific research. Decades of work have been put into developing fast numerical schemes for specific equations, but computational research in many fields is still largely software-limited. Here I will discuss how algorithmic flexibility and composability can enable new science, as illustrated by the Dedalus Project. Dedalus is an open-source Python framework that automates the solution of general PDEs using spectral methods. High-level abstractions allow users to symbolically specify equations, parallelize and scale their solvers to thousands of cores, and perform arbitrary analysis with the computed solutions. I will provide an overview the code’s design and the underlying sparse spectral algorithms, and show how they are enabling novel simulations of diverse hydrodynamical systems. I will include astrophysical and geophysical applications using new bases for tensor-valued equations in spherical domains, immersed boundary methods for multiphase flows, and multi-domain simulations interfacing Dedalus with other PDE and integral equation solvers.</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS&diff=19271Applied/ACMS2020-03-17T00:24:05Z<p>Spagnolie: </p>
<hr />
<div>__NOTOC__<br />
<br />
= Applied and Computational Mathematics Seminar =<br />
<br />
*'''When:''' Fridays at 2:25pm (except as otherwise indicated)<br />
*'''Where:''' 901 Van Vleck Hall<br />
*'''Organizers:''' [http://www.math.wisc.edu/~qinli/ Qin Li], [http://www.math.wisc.edu/~spagnolie/ Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''To join the ACMS mailing list:''' See [https://admin.lists.wisc.edu/index.php?p=11&l=acms mailing list] website.<br />
<br />
<br><br />
<br />
<br />
== Spring 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
| Jan 31<br />
|[https://www.math.wisc.edu/~hung/ Hung Tran] (UW-Madison)<br />
|''[[Applied/ACMS/absS20#Hung Tran (UW-Madison)| Coagulation-Fragmentation equations with multiplicative coagulation kernel and constant fragmentation kernel]]''<br />
| Li<br />
|-<br />
| Feb 7<br />
|[https://www.usna.edu/Users/weaprcon/avramov/index.php Svetlana Avramov-Zamurovic] (United States Naval Academy)<br />
|''[[Applied/ACMS/absS20#Svetlana Avramov-Zamurovic (United States Naval Academy)|Experiments with Structured Light]]''<br />
| Stechmann<br />
|-<br />
| Feb 14<br />
|[http://math.mit.edu/~vadicgor/ Vadim Gorin] (UW-Madison)<br />
|''[[Applied/ACMS/absS20#Vadim Gorin (UW-Madison)| Integrability of KPZ equation]]''<br />
| Li<br />
|-<br />
| Feb 21<br />
|[http://www.personal.psu.edu/jzh13/ John Harlim] (Penn State University)<br />
|''[[Applied/ACMS/absS20#Speaker (Penn State University)|Modeling Dynamical Systems with Machine Learning]]''<br />
| Chen<br />
|-<br />
| Feb 28<br />
|[https://cims.nyu.edu/~yangq/ Qiu Yang] (NYU/UVic/NCAR)<br />
|''[[Applied/ACMS/absS20#Speaker (NYU/UVic/NCAR)|Upscale Impact of Mesoscale Convective Systems on the MJO and Its Parameterization in Coarse-Resolution GCMs]]''<br />
| Chen<br />
|-<br />
| Mar 6<br />
|[https://directory.engr.wisc.edu/ep/Faculty/Bronkhorst_Curt/ Curt Bronkhorst] (UW-Madison Engineering Physics)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|Computational Prediction of Shear Banding and Deformation Twinning in Metals]]''<br />
| Smith<br />
|-<br />
| Mar 13<br />
|[http://www.columbia.edu/~ktm2132/ Kyle Mandli] (Columbia)<br />
|''[[Applied/ACMS/absS20#Kyle Mandli (Columbia)|TBA]]''<br />
| Wally<br />
|-<br />
| Mar 20<br />
|[Spring break] (Spring Break!)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|title]]''<br />
| host<br />
|-<br />
| Mar 27<br />
|[http://www-personal.umich.edu/~jcsch/ John Schotland] (U Mich)<br />
|''[[Applied/ACMS/absS20#John Schotland (Michigan)|title]]''<br />
| host<br />
|-<br />
| Apr 3<br />
|[http://keaton-burns.com/ Keaton Burns] (MIT)<br />
|''[[Applied/ACMS/absS20#Keaton Burns (MIT)| VIRTUAL! Details to come. ]]''<br />
| Spagnolie<br />
|-<br />
| Apr 10<br />
|[https://www.princeton.edu/~lecoanet/ Daniel Lecoanet] (Princeton)<br />
|''[[Applied/ACMS/absS20#Daniel Lecoanet (Princeton)|TBA]]''<br />
| Wally<br />
|-<br />
| Apr 17<br />
|[https://www.ornl.gov/staff-profile/hoang-tran Hoang Tran] (Oak Ridge National Laboratory)<br />
|''[[Applied/ACMS/absS20#Hoang Tran (institution)|title]]''<br />
| Tran<br />
|-<br />
| Apr 24<br />
|[https://www.pml.unc.edu/ Pedro Saenz] (UNC)<br />
|''[[Applied/ACMS/absF19#Pedro Saenz (UNC)|TBA]]''<br />
| Spagnolie<br />
|-<br />
|}<br />
<br />
== Future semesters ==<br />
<br />
<br />
<br />
<br />
----<br />
<br />
== Archived semesters ==<br />
<br />
*[[Applied/ACMS/Spring2020|Spring 2020]]<br />
*[[Applied/ACMS/Fall2019|Fall 2019]]<br />
*[[Applied/ACMS/Spring2019|Spring 2019]]<br />
*[[Applied/ACMS/Fall2018|Fall 2018]]<br />
*[[Applied/ACMS/Spring2018|Spring 2018]]<br />
*[[Applied/ACMS/Fall2017|Fall 2017]]<br />
*[[Applied/ACMS/Spring2017|Spring 2017]]<br />
*[[Applied/ACMS/Fall2016|Fall 2016]]<br />
*[[Applied/ACMS/Spring2016|Spring 2016]]<br />
*[[Applied/ACMS/Fall2015|Fall 2015]]<br />
*[[Applied/ACMS/Spring2015|Spring 2015]]<br />
*[[Applied/ACMS/Fall2014|Fall 2014]]<br />
*[[Applied/ACMS/Spring2014|Spring 2014]]<br />
*[[Applied/ACMS/Fall2013|Fall 2013]]<br />
*[[Applied/ACMS/Spring2013|Spring 2013]]<br />
*[[Applied/ACMS/Fall2012|Fall 2012]]<br />
*[[Applied/ACMS/Spring2012|Spring 2012]]<br />
*[[Applied/ACMS/Fall2011|Fall 2011]]<br />
*[[Applied/ACMS/Spring2011|Spring 2011]]<br />
*[[Applied/ACMS/Fall2010|Fall 2010]]<br />
<!--<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring10.html Spring 2010]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall09.html Fall 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring09.html Spring 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall08.html Fall 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring08.html Spring 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall07.html Fall 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring07.html Spring 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall06.html Fall 2006]<br />
--><br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS&diff=19254Applied/ACMS2020-03-12T17:48:36Z<p>Spagnolie: /* Spring 2020 */</p>
<hr />
<div>__NOTOC__<br />
<br />
= Applied and Computational Mathematics Seminar =<br />
<br />
*'''When:''' Fridays at 2:25pm (except as otherwise indicated)<br />
*'''Where:''' 901 Van Vleck Hall<br />
*'''Organizers:''' [http://www.math.wisc.edu/~qinli/ Qin Li], [http://www.math.wisc.edu/~spagnolie/ Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''To join the ACMS mailing list:''' See [https://admin.lists.wisc.edu/index.php?p=11&l=acms mailing list] website.<br />
<br />
<br><br />
<br />
<br />
== Spring 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
| Jan 31<br />
|[https://www.math.wisc.edu/~hung/ Hung Tran] (UW-Madison)<br />
|''[[Applied/ACMS/absS20#Hung Tran (UW-Madison)| Coagulation-Fragmentation equations with multiplicative coagulation kernel and constant fragmentation kernel]]''<br />
| Li<br />
|-<br />
| Feb 7<br />
|[https://www.usna.edu/Users/weaprcon/avramov/index.php Svetlana Avramov-Zamurovic] (United States Naval Academy)<br />
|''[[Applied/ACMS/absS20#Svetlana Avramov-Zamurovic (United States Naval Academy)|Experiments with Structured Light]]''<br />
| Stechmann<br />
|-<br />
| Feb 14<br />
|[http://math.mit.edu/~vadicgor/ Vadim Gorin] (UW-Madison)<br />
|''[[Applied/ACMS/absS20#Vadim Gorin (UW-Madison)| Integrability of KPZ equation]]''<br />
| Li<br />
|-<br />
| Feb 21<br />
|[http://www.personal.psu.edu/jzh13/ John Harlim] (Penn State University)<br />
|''[[Applied/ACMS/absS20#Speaker (Penn State University)|Modeling Dynamical Systems with Machine Learning]]''<br />
| Chen<br />
|-<br />
| Feb 28<br />
|[https://cims.nyu.edu/~yangq/ Qiu Yang] (NYU/UVic/NCAR)<br />
|''[[Applied/ACMS/absS20#Speaker (NYU/UVic/NCAR)|Upscale Impact of Mesoscale Convective Systems on the MJO and Its Parameterization in Coarse-Resolution GCMs]]''<br />
| Chen<br />
|-<br />
| Mar 6<br />
|[https://directory.engr.wisc.edu/ep/Faculty/Bronkhorst_Curt/ Curt Bronkhorst] (UW-Madison Engineering Physics)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|Computational Prediction of Shear Banding and Deformation Twinning in Metals]]''<br />
| Smith<br />
|-<br />
| Mar 13<br />
|[http://www.columbia.edu/~ktm2132/ Kyle Mandli] (Columbia)<br />
|''[[Applied/ACMS/absS20#Kyle Mandli (Columbia)|TBA]]''<br />
| Wally<br />
|-<br />
| Mar 20<br />
|[Spring break] (Spring Break!)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|title]]''<br />
| host<br />
|-<br />
| Mar 27<br />
|[http://www-personal.umich.edu/~jcsch/ John Schotland] (U Mich)<br />
|''[[Applied/ACMS/absS20#John Schotland (Michigan)|title]]''<br />
| host<br />
|-<br />
| Apr 3<br />
|[http://keaton-burns.com/ Keaton Burns] (MIT)<br />
|''[[Applied/ACMS/absS20#Keaton Burns (MIT)|Cancelled, to be rescheduled]]''<br />
| Spagnolie<br />
|-<br />
| Apr 10<br />
|[https://www.princeton.edu/~lecoanet/ Daniel Lecoanet] (Princeton)<br />
|''[[Applied/ACMS/absS20#Daniel Lecoanet (Princeton)|TBA]]''<br />
| Wally<br />
|-<br />
| Apr 17<br />
|[https://www.ornl.gov/staff-profile/hoang-tran Hoang Tran] (Oak Ridge National Laboratory)<br />
|''[[Applied/ACMS/absS20#Hoang Tran (institution)|title]]''<br />
| Tran<br />
|-<br />
| Apr 24<br />
|[https://www.pml.unc.edu/ Pedro Saenz] (UNC)<br />
|''[[Applied/ACMS/absF19#Pedro Saenz (UNC)|TBA]]''<br />
| Spagnolie<br />
|-<br />
|}<br />
<br />
== Future semesters ==<br />
<br />
<br />
<br />
<br />
----<br />
<br />
== Archived semesters ==<br />
<br />
*[[Applied/ACMS/Spring2020|Spring 2020]]<br />
*[[Applied/ACMS/Fall2019|Fall 2019]]<br />
*[[Applied/ACMS/Spring2019|Spring 2019]]<br />
*[[Applied/ACMS/Fall2018|Fall 2018]]<br />
*[[Applied/ACMS/Spring2018|Spring 2018]]<br />
*[[Applied/ACMS/Fall2017|Fall 2017]]<br />
*[[Applied/ACMS/Spring2017|Spring 2017]]<br />
*[[Applied/ACMS/Fall2016|Fall 2016]]<br />
*[[Applied/ACMS/Spring2016|Spring 2016]]<br />
*[[Applied/ACMS/Fall2015|Fall 2015]]<br />
*[[Applied/ACMS/Spring2015|Spring 2015]]<br />
*[[Applied/ACMS/Fall2014|Fall 2014]]<br />
*[[Applied/ACMS/Spring2014|Spring 2014]]<br />
*[[Applied/ACMS/Fall2013|Fall 2013]]<br />
*[[Applied/ACMS/Spring2013|Spring 2013]]<br />
*[[Applied/ACMS/Fall2012|Fall 2012]]<br />
*[[Applied/ACMS/Spring2012|Spring 2012]]<br />
*[[Applied/ACMS/Fall2011|Fall 2011]]<br />
*[[Applied/ACMS/Spring2011|Spring 2011]]<br />
*[[Applied/ACMS/Fall2010|Fall 2010]]<br />
<!--<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring10.html Spring 2010]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall09.html Fall 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring09.html Spring 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall08.html Fall 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring08.html Spring 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall07.html Fall 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring07.html Spring 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall06.html Fall 2006]<br />
--><br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS&diff=19253Applied/ACMS2020-03-12T17:48:10Z<p>Spagnolie: </p>
<hr />
<div>__NOTOC__<br />
<br />
= Applied and Computational Mathematics Seminar =<br />
<br />
*'''When:''' Fridays at 2:25pm (except as otherwise indicated)<br />
*'''Where:''' 901 Van Vleck Hall<br />
*'''Organizers:''' [http://www.math.wisc.edu/~qinli/ Qin Li], [http://www.math.wisc.edu/~spagnolie/ Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''To join the ACMS mailing list:''' See [https://admin.lists.wisc.edu/index.php?p=11&l=acms mailing list] website.<br />
<br />
<br><br />
<br />
<br />
== Spring 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
| Jan 31<br />
|[https://www.math.wisc.edu/~hung/ Hung Tran] (UW-Madison)<br />
|''[[Applied/ACMS/absS20#Hung Tran (UW-Madison)| Coagulation-Fragmentation equations with multiplicative coagulation kernel and constant fragmentation kernel]]''<br />
| Li<br />
|-<br />
| Feb 7<br />
|[https://www.usna.edu/Users/weaprcon/avramov/index.php Svetlana Avramov-Zamurovic] (United States Naval Academy)<br />
|''[[Applied/ACMS/absS20#Svetlana Avramov-Zamurovic (United States Naval Academy)|Experiments with Structured Light]]''<br />
| Stechmann<br />
|-<br />
| Feb 14<br />
|[http://math.mit.edu/~vadicgor/ Vadim Gorin] (UW-Madison)<br />
|''[[Applied/ACMS/absS20#Vadim Gorin (UW-Madison)| Integrability of KPZ equation]]''<br />
| Li<br />
|-<br />
| Feb 21<br />
|[http://www.personal.psu.edu/jzh13/ John Harlim] (Penn State University)<br />
|''[[Applied/ACMS/absS20#Speaker (Penn State University)|Modeling Dynamical Systems with Machine Learning]]''<br />
| Chen<br />
|-<br />
| Feb 28<br />
|[https://cims.nyu.edu/~yangq/ Qiu Yang] (NYU/UVic/NCAR)<br />
|''[[Applied/ACMS/absS20#Speaker (NYU/UVic/NCAR)|Upscale Impact of Mesoscale Convective Systems on the MJO and Its Parameterization in Coarse-Resolution GCMs]]''<br />
| Chen<br />
|-<br />
| Mar 6<br />
|[https://directory.engr.wisc.edu/ep/Faculty/Bronkhorst_Curt/ Curt Bronkhorst] (UW-Madison Engineering Physics)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|Computational Prediction of Shear Banding and Deformation Twinning in Metals]]''<br />
| Smith<br />
|-<br />
| Mar 13<br />
|[http://www.columbia.edu/~ktm2132/ Kyle Mandli] (Columbia)<br />
|''[[Applied/ACMS/absS20#Kyle Mandli (Columbia)|TBA]]''<br />
| Wally<br />
|-<br />
| Mar 20<br />
|[Spring break] (Spring Break!)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|title]]''<br />
| host<br />
|-<br />
| Mar 27<br />
|[http://www-personal.umich.edu/~jcsch/ John Schotland] (U Mich)<br />
|''[[Applied/ACMS/absS20#John Schotland (Michigan)|title]]''<br />
| host<br />
|-<br />
| Apr 3<br />
|[http://keaton-burns.com/ Keaton Burns] (MIT)<br />
|''[[Applied/ACMS/absS20#Keaton Burns (MIT)|To be rescheduled]]''<br />
| Spagnolie<br />
|-<br />
| Apr 10<br />
|[https://www.princeton.edu/~lecoanet/ Daniel Lecoanet] (Princeton)<br />
|''[[Applied/ACMS/absS20#Daniel Lecoanet (Princeton)|TBA]]''<br />
| Wally<br />
|-<br />
| Apr 17<br />
|[https://www.ornl.gov/staff-profile/hoang-tran Hoang Tran] (Oak Ridge National Laboratory)<br />
|''[[Applied/ACMS/absS20#Hoang Tran (institution)|title]]''<br />
| Tran<br />
|-<br />
| Apr 24<br />
|[https://www.pml.unc.edu/ Pedro Saenz] (UNC)<br />
|''[[Applied/ACMS/absF19#Pedro Saenz (UNC)|TBA]]''<br />
| Spagnolie<br />
|-<br />
|}<br />
<br />
== Future semesters ==<br />
<br />
<br />
<br />
<br />
----<br />
<br />
== Archived semesters ==<br />
<br />
*[[Applied/ACMS/Spring2020|Spring 2020]]<br />
*[[Applied/ACMS/Fall2019|Fall 2019]]<br />
*[[Applied/ACMS/Spring2019|Spring 2019]]<br />
*[[Applied/ACMS/Fall2018|Fall 2018]]<br />
*[[Applied/ACMS/Spring2018|Spring 2018]]<br />
*[[Applied/ACMS/Fall2017|Fall 2017]]<br />
*[[Applied/ACMS/Spring2017|Spring 2017]]<br />
*[[Applied/ACMS/Fall2016|Fall 2016]]<br />
*[[Applied/ACMS/Spring2016|Spring 2016]]<br />
*[[Applied/ACMS/Fall2015|Fall 2015]]<br />
*[[Applied/ACMS/Spring2015|Spring 2015]]<br />
*[[Applied/ACMS/Fall2014|Fall 2014]]<br />
*[[Applied/ACMS/Spring2014|Spring 2014]]<br />
*[[Applied/ACMS/Fall2013|Fall 2013]]<br />
*[[Applied/ACMS/Spring2013|Spring 2013]]<br />
*[[Applied/ACMS/Fall2012|Fall 2012]]<br />
*[[Applied/ACMS/Spring2012|Spring 2012]]<br />
*[[Applied/ACMS/Fall2011|Fall 2011]]<br />
*[[Applied/ACMS/Spring2011|Spring 2011]]<br />
*[[Applied/ACMS/Fall2010|Fall 2010]]<br />
<!--<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring10.html Spring 2010]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall09.html Fall 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring09.html Spring 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall08.html Fall 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring08.html Spring 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall07.html Fall 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring07.html Spring 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall06.html Fall 2006]<br />
--><br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS&diff=19252Applied/ACMS2020-03-12T17:47:38Z<p>Spagnolie: /* Spring 2020 */</p>
<hr />
<div>__NOTOC__<br />
<br />
= Applied and Computational Mathematics Seminar =<br />
<br />
*'''When:''' Fridays at 2:25pm (except as otherwise indicated)<br />
*'''Where:''' 901 Van Vleck Hall<br />
*'''Organizers:''' [http://www.math.wisc.edu/~qinli/ Qin Li], [http://www.math.wisc.edu/~spagnolie/ Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''To join the ACMS mailing list:''' See [https://admin.lists.wisc.edu/index.php?p=11&l=acms mailing list] website.<br />
<br />
<br><br />
<br />
<br />
== Spring 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
| Jan 31<br />
|[https://www.math.wisc.edu/~hung/ Hung Tran] (UW-Madison)<br />
|''[[Applied/ACMS/absS20#Hung Tran (UW-Madison)| Coagulation-Fragmentation equations with multiplicative coagulation kernel and constant fragmentation kernel]]''<br />
| Li<br />
|-<br />
| Feb 7<br />
|[https://www.usna.edu/Users/weaprcon/avramov/index.php Svetlana Avramov-Zamurovic] (United States Naval Academy)<br />
|''[[Applied/ACMS/absS20#Svetlana Avramov-Zamurovic (United States Naval Academy)|Experiments with Structured Light]]''<br />
| Stechmann<br />
|-<br />
| Feb 14<br />
|[http://math.mit.edu/~vadicgor/ Vadim Gorin] (UW-Madison)<br />
|''[[Applied/ACMS/absS20#Vadim Gorin (UW-Madison)| Integrability of KPZ equation]]''<br />
| Li<br />
|-<br />
| Feb 21<br />
|[http://www.personal.psu.edu/jzh13/ John Harlim] (Penn State University)<br />
|''[[Applied/ACMS/absS20#Speaker (Penn State University)|Modeling Dynamical Systems with Machine Learning]]''<br />
| Chen<br />
|-<br />
| Feb 28<br />
|[https://cims.nyu.edu/~yangq/ Qiu Yang] (NYU/UVic/NCAR)<br />
|''[[Applied/ACMS/absS20#Speaker (NYU/UVic/NCAR)|Upscale Impact of Mesoscale Convective Systems on the MJO and Its Parameterization in Coarse-Resolution GCMs]]''<br />
| Chen<br />
|-<br />
| Mar 6<br />
|[https://directory.engr.wisc.edu/ep/Faculty/Bronkhorst_Curt/ Curt Bronkhorst] (UW-Madison Engineering Physics)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|Computational Prediction of Shear Banding and Deformation Twinning in Metals]]''<br />
| Smith<br />
|-<br />
| Mar 13<br />
|[http://www.columbia.edu/~ktm2132/ Kyle Mandli] (Columbia)<br />
|''[[Applied/ACMS/absS20#Kyle Mandli (Columbia)|TBA]]''<br />
| Wally<br />
|-<br />
| Mar 20<br />
|[Spring break] (Spring Break!)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|title]]''<br />
| host<br />
|-<br />
| Mar 27<br />
|[http://www-personal.umich.edu/~jcsch/ John Schotland] (U Mich)<br />
|''[[Applied/ACMS/absS20#John Schotland (Michigan)|title]]''<br />
| host<br />
|-<br />
| Apr 3<br />
|[http://keaton-burns.com/ Keaton Burns] (MIT) --> to be rescheduled.<br />
|''[[Applied/ACMS/absS20#Keaton Burns (MIT)|title]]''<br />
| Spagnolie<br />
|-<br />
| Apr 10<br />
|[https://www.princeton.edu/~lecoanet/ Daniel Lecoanet] (Princeton)<br />
|''[[Applied/ACMS/absS20#Daniel Lecoanet (Princeton)|TBA]]''<br />
| Wally<br />
|-<br />
| Apr 17<br />
|[https://www.ornl.gov/staff-profile/hoang-tran Hoang Tran] (Oak Ridge National Laboratory)<br />
|''[[Applied/ACMS/absS20#Hoang Tran (institution)|title]]''<br />
| Tran<br />
|-<br />
| Apr 24<br />
|[https://www.pml.unc.edu/ Pedro Saenz] (UNC)<br />
|''[[Applied/ACMS/absF19#Pedro Saenz (UNC)|TBA]]''<br />
| Spagnolie<br />
|-<br />
|}<br />
<br />
== Future semesters ==<br />
<br />
<br />
<br />
<br />
----<br />
<br />
== Archived semesters ==<br />
<br />
*[[Applied/ACMS/Spring2020|Spring 2020]]<br />
*[[Applied/ACMS/Fall2019|Fall 2019]]<br />
*[[Applied/ACMS/Spring2019|Spring 2019]]<br />
*[[Applied/ACMS/Fall2018|Fall 2018]]<br />
*[[Applied/ACMS/Spring2018|Spring 2018]]<br />
*[[Applied/ACMS/Fall2017|Fall 2017]]<br />
*[[Applied/ACMS/Spring2017|Spring 2017]]<br />
*[[Applied/ACMS/Fall2016|Fall 2016]]<br />
*[[Applied/ACMS/Spring2016|Spring 2016]]<br />
*[[Applied/ACMS/Fall2015|Fall 2015]]<br />
*[[Applied/ACMS/Spring2015|Spring 2015]]<br />
*[[Applied/ACMS/Fall2014|Fall 2014]]<br />
*[[Applied/ACMS/Spring2014|Spring 2014]]<br />
*[[Applied/ACMS/Fall2013|Fall 2013]]<br />
*[[Applied/ACMS/Spring2013|Spring 2013]]<br />
*[[Applied/ACMS/Fall2012|Fall 2012]]<br />
*[[Applied/ACMS/Spring2012|Spring 2012]]<br />
*[[Applied/ACMS/Fall2011|Fall 2011]]<br />
*[[Applied/ACMS/Spring2011|Spring 2011]]<br />
*[[Applied/ACMS/Fall2010|Fall 2010]]<br />
<!--<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring10.html Spring 2010]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall09.html Fall 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring09.html Spring 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall08.html Fall 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring08.html Spring 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall07.html Fall 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring07.html Spring 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall06.html Fall 2006]<br />
--><br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/Physical_Applied_Math&diff=19051Applied/Physical Applied Math2020-02-18T15:22:34Z<p>Spagnolie: /* Spring 2020 */</p>
<hr />
<div>= Physical Applied Math Group Meeting =<br />
<br />
*'''When:''' Thursdays at 4:00pm (unless there is a [https://www.math.wisc.edu/deptmeetings Department Meeting])<br />
*'''Where:''' 901 Van Vleck Hall<br />
*'''Organizers:''' [http://www.math.wisc.edu/~spagnolie Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''To join the Physical Applied Math mailing list:''' See the [https://admin.lists.wisc.edu/index.php?p=11&l=phys_appl_math mailing list website].<br />
<br />
== Spring 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
|-<br />
|Jan. 30<br />
|Jean-Luc<br />
|Organizational meeting; [https://www.dropbox.com/s/bnjpyud6h8u3lav/homog_periodic_lattice_group_meeting.pdf?dl=0 Homogenization of a periodic lattice]<br />
|-<br />
|Feb. 6<br />
|Gage<br />
|Krasilov et al., [https://bura.brunel.ac.uk/bitstream/2438/419/1/Growing%20Random%20Sequences.pdf Growing random sequences]<br> Makover and McGowan, [https://arxiv.org/abs/math/0510159 An elementary proof that random Fibonacci sequences grow exponentially]<br />
|-<br />
|Feb. 13<br />
|<br />
|''Faculty Meeting''<br />
|-<br />
|Feb. 20<br />
|Saverio<br />
|Greengard and Jiang, [https://epubs.siam.org/doi/abs/10.1137/18M1216158 A New Mixed Potential Representation for Unsteady, Incompressible Flow]<br />
|-<br />
|Feb. 27<br />
|Wil<br />
|''EC?''<br />
|-<br />
|Mar. 5<br />
|<br />
|''Faculty Meeting''<br />
|-<br />
|Mar. 12<br />
|Ruifu<br />
|''EC?''<br />
|-<br />
|Mar. 19<br />
|<br />
|''Spring Break''<br />
|-<br />
|Mar. 26<br />
|<br />
|''Faculty Meeting''<br />
|-<br />
|Apr. 2<br />
|Keaton Burns?<br />
|<br />
|-<br />
|Apr. 9<br />
|<br />
|<br />
|-<br />
|Apr. 16<br />
|<br />
|<br />
|-<br />
|Apr. 23<br />
|<br />
|''Faculty Meeting''<br />
|-<br />
|Apr. 30<br />
|<br />
|<br />
|-<br />
|}<br />
<br />
== Archived semesters ==<br />
*[[Applied/Physical_Applied_Math/Fall2019|Fall 2019]]<br />
*[[Applied/Physical_Applied_Math/Spring2019|Spring 2019]]<br />
*[[Applied/Physical_Applied_Math/Fall2018|Fall 2018]]<br />
*[[Applied/Physical_Applied_Math/Spring2018|Spring 2018]]<br />
*[[Applied/Physical_Applied_Math/Fall2017|Fall 2017]]<br />
*[[Applied/Physical_Applied_Math/Spring2017|Spring 2017]]<br />
*[[Applied/Physical_Applied_Math/Fall2016|Fall 2016]]<br />
*[[Applied/Physical_Applied_Math/Spring2016|Spring 2016]]<br />
*[[Applied/Physical_Applied_Math/Fall2015|Fall 2015]]<br />
*[[Applied/Physical_Applied_Math/Spring2015|Spring 2015]]<br />
*[[Applied/Physical_Applied_Math/Summer2014|Summer 2014]]<br />
*[[Applied/Physical_Applied_Math/Spring2014|Spring 2014]]<br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Colloquia/Spring2020&diff=18960Colloquia/Spring20202020-02-09T18:08:13Z<p>Spagnolie: </p>
<hr />
<div>= Mathematics Colloquium =<br />
<br />
All colloquia are on Fridays at 4:00 pm in Van Vleck B239, '''unless otherwise indicated'''.<br />
<br />
<br />
<br />
==Fall 2019==<br />
{| cellpadding="8"<br />
!align="left" | date <br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
|Sept 6 '''Room 911'''<br />
| Will Sawin (Columbia)<br />
| [[#Will Sawin (Columbia) | On Chowla's Conjecture over F_q[T] ]]<br />
| Marshall<br />
|-<br />
|Sept 13<br />
| [https://www.math.ksu.edu/~soibel/ Yan Soibelman] (Kansas State)<br />
|[[#Yan Soibelman (Kansas State)| Riemann-Hilbert correspondence and Fukaya categories ]]<br />
| Caldararu<br />
|<br />
|-<br />
|Sept 16 '''Monday Room 911'''<br />
| [http://mate.dm.uba.ar/~alidick/ Alicia Dickenstein] (Buenos Aires)<br />
|[[#Alicia Dickenstein (Buenos Aires)| Algebra and geometry in the study of enzymatic cascades ]]<br />
| Craciun<br />
|<br />
|-<br />
|Sept 20<br />
| [https://math.duke.edu/~jianfeng/ Jianfeng Lu] (Duke)<br />
|[[#Jianfeng Lu (Duke) | How to "localize" the computation?]]<br />
| Qin<br />
|<br />
|-<br />
|Sept 26 '''Thursday 3-4 pm Room 911'''<br />
| [http://eugeniacheng.com/ Eugenia Cheng] (School of the Art Institute of Chicago)<br />
| [[#Eugenia Cheng (School of the Art Institute of Chicago)| Character vs gender in mathematics and beyond ]]<br />
| Marshall / Friends of UW Madison Libraries<br />
|<br />
|-<br />
|Sept 27<br />
|<br />
|<br />
|-<br />
|Oct 4<br />
|<br />
|<br />
|-<br />
|Oct 11<br />
| Omer Mermelstein (Madison)<br />
| [[#Omer Mermelstein (Madison)| Generic flat pregeometries ]]<br />
|Andrews<br />
|<br />
|-<br />
|Oct 18<br />
| Shamgar Gurevich (Madison)<br />
| [[#Shamgar Gurevich (Madison) | Harmonic Analysis on GL(n) over Finite Fields ]]<br />
| Marshall<br />
|-<br />
|Oct 25<br />
|<br />
|-<br />
|Nov 1<br />
|Elchanan Mossel (MIT)<br />
|Distinguished Lecture<br />
|Roch<br />
|-<br />
|Nov 8<br />
|Jose Rodriguez (UW-Madison)<br />
|[[#Jose Rodriguez (UW-Madison) | Nearest Point Problems and Euclidean Distance Degrees]]<br />
|Erman<br />
|-<br />
|Nov 13 '''Wednesday 4-5pm'''<br />
|Ananth Shankar (MIT)<br />
|Exceptional splitting of abelian surfaces<br />
|-<br />
|Nov 20 '''Wednesday 4-5pm'''<br />
|Franca Hoffman (Caltech)<br />
|[[#Franca Hoffman (Caltech) | Gradient Flows: From PDE to Data Analysis]]<br />
|Smith<br />
|-<br />
|Nov 22<br />
| Jeffrey Danciger (UT Austin)<br />
| [[#Jeffrey Danciger (UT Austin) | "Affine geometry and the Auslander Conjecture"]]<br />
| Kent<br />
|-<br />
|Nov 25 '''Monday 4-5 pm Room 911'''<br />
|Tatyana Shcherbina (Princeton)<br />
| [[# Tatyana Shcherbina (Princeton)| "Random matrix theory and supersymmetry techniques"]]<br />
|Roch<br />
|-<br />
|Nov 29<br />
|Thanksgiving<br />
|<br />
|-<br />
|Dec 2 '''Monday 4-5pm'''<br />
|Tingran Gao (University of Chicago)<br />
| [[#Tingran Gao (University of Chicago)| "Manifold Learning on Fibre Bundles"]]<br />
|Smith<br />
|-<br />
|Dec 4 '''Wednesday 4-5 pm Room 911'''<br />
|Andrew Zimmer (LSU)<br />
|[[#Andrew Zimmer (LSU)| "Intrinsic and extrinsic geometries in several complex variables"]]<br />
|Gong<br />
|-<br />
|Dec 6<br />
|Charlotte Chan (MIT)<br />
|[[#Charlotte Chan (MIT)|"Flag varieties and representations of p-adic groups"]]<br />
|Erman<br />
|-<br />
|Dec 9 '''Monday 4-5 pm'''<br />
|Hui Yu (Columbia)<br />
|[[#Hui Yu (Columbia)|Singular sets in obstacle problems]]<br />
|Tran<br />
|-<br />
|Dec 11 '''Wednesday 2:30-3:30pm Room 911'''<br />
|Alex Waldron (Michigan)<br />
|[[#Alex Waldron (Michigan)|Gauge theory and geometric flows]]<br />
|Paul<br />
|-<br />
|Dec 11 '''Wednesday 4-5pm'''<br />
|Nick Higham (Manchester)<br />
|[[#Nick Higham (Manchester)|LAA lecture: Challenges in Multivalued Matrix Functions]]<br />
|Brualdi<br />
|-<br />
|Dec 13 <br />
|Chenxi Wu (Rutgers)<br />
|[[#Chenxi Wu (Rutgers)|Kazhdan's theorem on metric graphs]]<br />
|Ellenberg<br />
|-<br />
|Dec 18 '''Wednesday 4-5pm'''<br />
|Ruobing Zhang (Stony Brook)<br />
|[[#Ruobing Zhang (Stony Brook)|Geometry and analysis of degenerating Calabi-Yau manifolds]]<br />
|Paul<br />
|-<br />
|}<br />
<br />
==Spring 2020==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date <br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|<br />
|-<br />
|Jan 10<br />
|Thomas Lam (Michigan) <br />
|[[#Thomas Lam (Michigan) |Positive geometries and string theory amplitudes]]<br />
|Erman<br />
|-<br />
|Jan 21 '''Tuesday 4-5 pm in B139'''<br />
|[http://www.nd.edu/~cholak/ Peter Cholak] (Notre Dame) <br />
|[[#Peter Cholak (Notre Dame) |What can we compute from solutions to combinatorial problems?]]<br />
|Lempp<br />
|-<br />
|Jan 24<br />
|[https://math.duke.edu/people/saulo-orizaga Saulo Orizaga] (Duke)<br />
|[[#Saulo Orizaga (Duke) | Introduction to phase field models and their efficient numerical implementation ]]<br />
|<br />
|-<br />
|Jan 27 '''Monday 4-5 pm in 911'''<br />
|[https://math.yale.edu/people/caglar-uyanik Caglar Uyanik] (Yale)<br />
|[[#Caglar Uyanik (Yale) | Hausdorff dimension and gap distribution in billiards ]]<br />
|Ellenberg<br />
|-<br />
|Jan 29 '''Wednesday 4-5 pm'''<br />
|[https://ajzucker.wordpress.com/ Andy Zucker] (Lyon)<br />
|[[#Andy Zucker (Lyon) |Topological dynamics of countable groups and structures]]<br />
|Soskova/Lempp<br />
|-<br />
|Jan 31 <br />
|[https://services.math.duke.edu/~pierce/ Lillian Pierce] (Duke)<br />
|[[#Lillian Pierce (Duke) |On Bourgain’s counterexample for the Schrödinger maximal function]]<br />
|Marshall/Seeger<br />
|-<br />
|Feb 7<br />
|[https://web.math.princeton.edu/~jkileel/ Joe Kileel] (Princeton)<br />
|[[#Joe Kileel (Princeton) |Inverse Problems, Imaging and Tensor Decomposition]]<br />
|Roch<br />
|-<br />
|Feb 10<br />
|[https://clvinzan.math.ncsu.edu/ Cynthia Vinzant] (NCSU)<br />
|[[#Cynthia Vinzant (NCSU) |Matroids, log-concavity, and expanders]]<br />
|Roch/Erman<br />
|-<br />
|Feb 12 '''Wednesday 4-5 pm in VV 911'''<br />
|[https://www.machuang.org/ Jinzi Mac Huang] (UCSD)<br />
|[[#Jinzi Mac Huang (UCSD) |Mass transfer through fluid-structure interactions]]<br />
|Spagnolie<br />
|-<br />
|Feb 14<br />
|[https://math.unt.edu/people/william-chan/ William Chan] (University of North Texas)<br />
|[[#William Chan (University of North Texas) |Definable infinitary combinatorics under determinacy]]<br />
|Soskova/Lempp<br />
|-<br />
|Feb 17<br />
|[https://yisun.io/ Yi Sun] (Columbia)<br />
|[[#Yi Sun (Columbia) |TBA]]<br />
|Roch<br />
|-<br />
|Feb 21<br />
|Shai Evra (IAS)<br />
|<br />
|Gurevich<br />
|<br />
|-<br />
|Feb 28<br />
|Brett Wick (Washington University, St. Louis)<br />
|<br />
|Seeger<br />
|-<br />
|March 6<br />
| Jessica Fintzen (Michigan)<br />
|<br />
|Marshall<br />
|-<br />
|March 13<br />
|<br />
|-<br />
|March 20<br />
|Spring break<br />
|<br />
|-<br />
|March 27<br />
|[https://max.lieblich.us/ Max Lieblich] (Univ. of Washington, Seattle)<br />
|<br />
|Boggess, Sankar<br />
|-<br />
|April 3<br />
|Caroline Turnage-Butterbaugh (Carleton College)<br />
|<br />
|Marshall<br />
|-<br />
|April 10<br />
| Sarah Koch (Michigan)<br />
|<br />
| Bruce (WIMAW)<br />
|-<br />
|April 17<br />
|<br />
|<br />
|<br />
|-<br />
|April 23<br />
|Martin Hairer (Imperial College London)<br />
|Wolfgang Wasow Lecture<br />
|Hao Shen<br />
|-<br />
|April 24<br />
|Natasa Sesum (Rutgers University)<br />
|<br />
|Angenent<br />
|-<br />
|May 1<br />
|Robert Lazarsfeld (Stony Brook)<br />
|Distinguished lecture<br />
|Erman<br />
|}<br />
<br />
== Abstracts ==<br />
<br />
<br />
===Will Sawin (Columbia)===<br />
<br />
Title: On Chowla's Conjecture over F_q[T]<br />
<br />
Abstract: The Mobius function in number theory is a sequences of 1s, <br />
-1s, and 0s, which is simple to define and closely related to the <br />
prime numbers. Its behavior seems highly random. Chowla's conjecture <br />
is one precise formalization of this randomness, and has seen recent <br />
work by Matomaki, Radziwill, Tao, and Teravainen making progress on <br />
it. In joint work with Mark Shusterman, we modify this conjecture by <br />
replacing the natural numbers parameterizing this sequence with <br />
polynomials over a finite field. Under mild conditions on the finite <br />
field, we are able to prove a strong form of this conjecture. The <br />
proof is based on taking a geometric perspective on the problem, and <br />
succeeds because we are able to simplify the geometry using a trick <br />
based on the strange properties of polynomial derivatives over finite <br />
fields.<br />
<br />
<br />
===Yan Soibelman (Kansas State)===<br />
<br />
Title: Riemann-Hilbert correspondence and Fukaya categories<br />
<br />
Abstract: In this talk I am going to discuss the role of Fukaya categories in the Riemann-Hilbert correspondence<br />
for differential, q-difference and elliptic difference equations in dimension one.<br />
This approach not only gives a unified answer for several versions of the Riemann-Hilbert correspondence but also leads to a natural formulation<br />
of the non-abelian Hodge theory in dimension one. It also explains why periodic monopoles<br />
should appear as harmonic objects in this generalized non-abelian Hodge theory.<br />
All that is a part of the bigger project ``Holomorphic Floer theory",<br />
joint with Maxim Kontsevich.<br />
<br />
<br />
===Alicia Dickenstein (Buenos Aires)===<br />
<br />
Title: Algebra and geometry in the study of enzymatic cascades<br />
<br />
Abstract: In recent years, techniques from computational and real algebraic geometry have been successfully used to address mathematical challenges in systems biology. The algebraic theory of chemical reaction systems aims to understand their dynamic behavior by taking advantage of the inherent algebraic structure in the kinetic equations, and does not need the determination of the parameters a priori, which can be theoretically or practically impossible.<br />
I will give a gentle introduction to general results based on the network structure. In particular, I will describe a general framework for biological systems, called MESSI systems, that describe Modifications of type Enzyme-Substrate or Swap with Intermediates, and include many networks that model post-translational modifications of proteins inside the cell. I will also outline recent methods to address the important question of multistationarity, in particular in the study of enzymatic cascades, and will point out some of the mathematical challenges that arise from this application.<br />
<br />
<br />
=== Jianfeng Lu (Duke) ===<br />
Title: How to ``localize" the computation?<br />
<br />
It is often desirable to restrict the numerical computation to a local region to achieve best balance between accuracy and affordability in scientific computing. It is important to avoid artifacts and guarantee predictable modelling while artificial boundary conditions have to be introduced to restrict the computation. In this talk, we will discuss some recent understanding on how to achieve such local computation in the context of topological edge states and elliptic random media.<br />
<br />
<br />
===Eugenia Cheng (School of the Art Institute of Chicago)===<br />
<br />
Title: Character vs gender in mathematics and beyond<br />
<br />
Abstract: This presentation will be based on my experience of being a female mathematician, and teaching mathematics at all levels from elementary school to grad school. The question of why women are under-represented in mathematics is complex and there are no simple answers, only many many contributing factors. I will focus on character traits, and argue that if we focus on this rather than gender we can have a more productive and less divisive conversation. To try and focus on characters rather than genders I will introduce gender-neutral character adjectives "ingressive" and "congressive" to replace masculine and feminine. I will share my experience of teaching congressive abstract mathematics to art students, in a congressive way, and the possible effects this could have for everyone in mathematics, not just women.<br />
<br />
<br />
===Omer Mermelstein (Madison)===<br />
<br />
Title: Generic flat pregeometries<br />
<br />
Abstract: In model theory, the tamest of structures are the strongly minimal ones -- those in which every equation in a single variable has either finitely many or cofinitely many solution. Algebraically closed fields and vector spaces are the canonical examples. Zilber’s conjecture, later refuted by Hrushovski, states that the source of geometric complexity in a strongly minimal structure must be algebraic. The property of "flatness" (strict gammoid) of a geometry (matroid) is that which guarantees Hrushovski's construction is devoid of any associative structure.<br />
The majority of the talk will explain what flatness is, how it should be thought of, and how closely it relates to hypergraphs and Hrushovski's construction method. Model theory makes an appearance only in the second part, where I will share results pertaining to the specific family of geometries arising from Hrushovski's methods.<br />
<br />
<br />
===Shamgar Gurevich (Madison)===<br />
<br />
Title: Harmonic Analysis on GL(n) over Finite Fields.<br />
<br />
Abstract: There are many formulas that express interesting properties of a finite group G in terms of sums over its characters. For evaluating or estimating these sums, one of the most salient quantities to understand is the character ratio:<br />
<br />
trace(ρ(g)) / dim(ρ),<br />
<br />
for an irreducible representation ρ of G and an element g of G. For example, Diaconis and Shahshahani stated a formula of the mentioned type for analyzing certain random walks on G.<br />
<br />
Recently, we discovered that for classical groups G over finite fields there is a natural invariant of representations that provides strong information on the character ratio. We call this invariant rank. <br />
<br />
This talk will discuss the notion of rank for the group GLn over finite fields, demonstrate how it controls the character ratio, and explain how one can apply the results to verify mixing time and rate for certain random walks.<br />
<br />
This is joint work with Roger Howe (Yale and Texas AM). The numerics for this work was carried by Steve Goldstein (Madison)<br />
<br />
<br />
===Jose Rodriguez (UW-Madison)===<br />
<br />
Abstract: Determining the closest point to a model (subset of Euclidean space) is an important problem in many applications in science,<br />
engineering, and statistics. One way to solve this problem is by minimizing the squared Euclidean distance function using a gradient<br />
descent approach. However, when there are multiple local minima, there is no guarantee of convergence to the true global minimizer.<br />
An alternative method is to determine the critical points of an objective function on the model.<br />
In algebraic statistics, the models of interest are algebraic sets, i.e., solution sets to a system of multivariate polynomial equations. In this situation, the number of critical points of the squared Euclidean distance function on the model’s Zariski closure is a topological invariant called the Euclidean distance degree (ED degree).<br />
In this talk, I will present some models from computer vision and statistics that may be described as algebraic sets. Moreover,<br />
I will describe a topological method for determining a Euclidean distance degree and a numerical algebraic geometry approach for<br />
determining critical points of the squared Euclidean distance function.<br />
<br />
<br />
===Ananth Shankar (MIT)===<br />
<br />
Abstract: An abelian surface 'splits' if it admits a non-trivial map to some elliptic curve. It is well known that the set of abelian surfaces that split are sparse in the set of all abelian surfaces. Nevertheless, we prove that there are infinitely many split abelian surfaces in arithmetic one-parameter families of generically non-split abelian surfaces. I will describe this work, and if time permits, mention generalizations of this result to the setting of K3 surfaces, as well as applications to the dynamics of hecke orbits. This is joint work with Tang, Maulik-Tang, and Shankar-Tang-Tayou.<br />
<br />
<br />
===Franca Hoffman (Caltech)===<br />
<br />
Title: Gradient Flows: From PDE to Data Analysis.<br />
<br />
Abstract: Certain diffusive PDEs can be viewed as infinite-dimensional gradient flows. This fact has led to the development of new tools in various areas of mathematics ranging from PDE theory to data science. In this talk, we focus on two different directions: model-driven approaches and data-driven approaches.<br />
In the first part of the talk we use gradient flows for analyzing non-linear and non-local aggregation-diffusion equations when the corresponding energy functionals are not necessarily convex. Moreover, the gradient flow structure enables us to make connections to well-known functional inequalities, revealing possible links between the optimizers of these inequalities and the equilibria of certain aggregation-diffusion PDEs.<br />
In the second part, we use and develop gradient flow theory to design novel tools for data analysis. We draw a connection between gradient flows and Ensemble Kalman methods for parameter estimation. We introduce the Ensemble Kalman Sampler - a derivative-free methodology for model calibration and uncertainty quantification in expensive black-box models. The interacting particle dynamics underlying our algorithm can be approximated by a novel gradient flow structure in a modified Wasserstein metric which reflects particle correlations. The geometry of this modified Wasserstein metric is of independent theoretical interest.<br />
<br />
<br />
=== Jeffrey Danciger (UT Austin) ===<br />
<br />
Title: Affine geometry and the Auslander Conjecture<br />
<br />
Abstract: The Auslander Conjecture is an analogue of Bieberbach’s theory of Euclidean crystallographic groups in the setting of affine geometry. It predicts that a complete affine manifold (a manifold equipped with a complete torsion-free flat affine connection) which is compact must have virtually solvable fundamental group. The conjecture is known up to dimension six, but is known to fail if the compactness assumption is removed, even in low dimensions. We discuss some history of this conjecture, give some basic examples, and then survey some recent advances in the study of non-compact complete affine manifolds with non-solvable fundamental group. <br />
Tools from the deformation theory of pseudo-Riemannian hyperbolic manifolds and also from higher Teichm&uuml;ller theory will enter the picture.<br />
<br />
<br />
=== Tatyana Shcherbina (Princeton) ===<br />
<br />
Title: Random matrix theory and supersymmetry techniques<br />
<br />
Abstract: Starting from the works of Erdos, Yau, Schlein with coauthors, the significant progress in understanding the universal behavior of many random graph and random matrix models were achieved. However for the random matrices with a special structure our understanding is still very limited. In this talk I am going to overview applications of another approach to the study of the local eigenvalues statistics in random matrix theory based on so-called supersymmetry techniques (SUSY). SUSY approach is based on the representation of the determinant as an integral over the Grassmann (anticommuting) variables. Combining this representation with the representation of an inverse determinant as an integral over the Gaussian complex field, SUSY allows to obtain an integral representation for the main spectral characteristics of random matrices such as limiting density, correlation functions, the resolvent's elements, etc. This method is widely (and successfully) used in the physics literature and is potentially very powerful but the rigorous control of the integral representations, which can be obtained by this method, is quite difficult, and it requires powerful analytic and statistical mechanics tools. In this talk we will discuss some recent progress in application of SUSY to the analysis of local spectral characteristics of the prominent ensemble of random band matrices, i.e. random matrices<br />
whose entries become negligible if their distance from the main diagonal exceeds a certain parameter called the band width. <br />
<br />
<br />
=== Tingran Gao (University of Chicago) ===<br />
<br />
Title: Manifold Learning on Fibre Bundles<br />
<br />
Abstract: Spectral geometry has played an important role in modern geometric data analysis, where the technique is widely known as Laplacian eigenmaps or diffusion maps. In this talk, we present a geometric framework that studies graph representations of complex datasets, where each edge of the graph is equipped with a non-scalar transformation or correspondence. This new framework models such a dataset as a fibre bundle with a connection, and interprets the collection of pairwise functional relations as defining a horizontal diffusion process on the bundle driven by its projection on the base. The eigenstates of this horizontal diffusion process encode the “consistency” among objects in the dataset, and provide a lens through which the geometry of the dataset can be revealed. We demonstrate an application of this geometric framework on evolutionary anthropology.<br />
<br />
<br />
=== Andrew Zimmer (LSU) ===<br />
<br />
Title: Intrinsic and extrinsic geometries in several complex variables<br />
<br />
Abstract: A bounded domain in complex Euclidean space, despite being one of the simplest types of manifolds, has a number of interesting geometric structures. When the domain is pseudoconvex, it has a natural intrinsic geometry: the complete Kaehler-Einstein metric constructed by Cheng-Yau and Mok-Yau. When the domain is smoothly bounded, there is also a natural extrinsic structure: the CR-geometry of the boundary. In this talk, I will describe connections between these intrinsic and extrinsic geometries. Then, I will discuss how these connections can lead to new analytic results.<br />
<br />
=== Charlotte Chan (MIT) ===<br />
<br />
Title: Flag varieties and representations of p-adic groups<br />
<br />
Abstract: In the 1950s, Borel, Weil, and Bott showed that the<br />
irreducible representations of a complex reductive group can be<br />
realized in the cohomology of line bundles on flag varieties. In the<br />
1970s, Deligne and Lusztig constructed a family of subvarieties of<br />
flag varieties whose cohomology realizes the irreducible<br />
representations of reductive groups over finite fields. I will survey<br />
these stories, explain recent progress towards finding geometric<br />
constructions of representations of p-adic groups, and discuss<br />
interactions with the Langlands program.<br />
<br />
=== Hui Yu (Columbia) ===<br />
<br />
Title: Singular sets in obstacle problems<br />
<br />
Abstract: One of the most important free boundary problems is the obstacle problem. The regularity of its free boundary has been studied for over half a century. In this talk, we review some classical results as well as exciting new developments. In particular, we discuss the recent resolution of the regularity of the singular set for the fully nonlinear obstacle problem. This talk is based on a joint work with Ovidiu Savin at Columbia University.<br />
<br />
=== Alex Waldron (Michigan) ===<br />
<br />
Title: Gauge theory and geometric flows<br />
<br />
Abstract: I will give a brief introduction to two major areas of research in differential geometry: gauge theory and geometric flows. I'll then introduce a geometric flow (Yang-Mills flow) arising from a variational problem with origins in physics, which has been studied by geometric analysts since the early 1980s. I'll conclude by discussing my own work on the behavior of Yang-Mills flow in the critical dimension (n = 4).<br />
<br />
=== Nick Higham (Manchester) ===<br />
<br />
Title: Challenges in Multivalued Matrix Functions<br />
<br />
Abstract: In this lecture I will discuss multivalued matrix functions that arise in solving various kinds of matrix equations. The matrix logarithm is the prototypical example, and my first interaction with Hans Schneider was about this function. Another example is the Lambert W function of a matrix, which is much less well known but has been attracting recent interest. A theme of the talk is the importance of choosing appropriate principal values and making sure that the correct choices of signs and branches are used,<br />
both in theory and in computation. I will give examples where incorrect results have previously been obtained.<br />
<br />
I focus on matrix inverse trigonometric and inverse hyperbolic functions, beginning by investigating existence and characterization. Turning to the principal values, various functional identities are derived, some of which are new even in the scalar case, including a “round trip” formula that relates acos(cos A) to A and similar formulas for the other inverse functions. Key tools used in the derivations are the matrix unwinding function and the matrix sign function.<br />
<br />
A new inverse scaling and squaring type algorithm employing a Schur decomposition and variable-degree Pade approximation is derived for computing acos, and it is shown how it can also be used to compute asin, acosh, and asinh.<br />
<br />
=== Chenxi Wu (Rutgers) ===<br />
<br />
Title: Kazhdan's theorem on metric graphs<br />
<br />
Abstract: I will give an introduction to the concept of canonical (arakelov) metric on a metric graph, which is related to combinatorial questions like the counting of spanning trees, and generalizes the corresponding concept on Riemann surfaces. I will also present a recent result in collaboration with Farbod Shokrieh on the convergence of canonical metric under normal covers.<br />
<br />
=== Ruobing Zhang (Stony Brook) ===<br />
<br />
Title: Geometry and analysis of degenerating Calabi-Yau manifolds<br />
<br />
Abstract: This talk concerns a naturally occurring family of degenerating Calabi-Yau manifolds. A primary tool in analyzing their behavior is to combine the recently developed structure theory for Einstein manifolds and multi-scale singularity analysis for degenerating nonlinear PDEs in the collapsed setting. Based on the algebraic degeneration, we will give precise and more quantitative descriptions of singularity formation from both metric and analytic points of view.<br />
<br />
=== Thomas Lam (Michigan) === <br />
<br />
Title: Positive geometries and string theory amplitudes<br />
<br />
Abstract: Inspired by developments in quantum field theory, we<br />
recently defined the notion of a positive geometry, a class of spaces<br />
that includes convex polytopes, positive parts of projective toric<br />
varieties, and positive parts of flag varieties. I will discuss some<br />
basic features of the theory and an application to genus zero string<br />
theory amplitudes. As a special case, we obtain the Euler beta<br />
function, familiar to mathematicians, as the "stringy canonical form"<br />
of the closed interval.<br />
<br />
This talk is based on joint work with Arkani-Hamed, Bai, and He.<br />
<br />
=== Peter Cholak (Notre Dame) ===<br />
<br />
Title: What can we compute from solutions to combinatorial problems?<br />
<br />
Abstract: This will be an introductory talk to an exciting current <br />
research area in mathematical logic. Mostly we are interested in <br />
solutions to Ramsey's Theorem. Ramsey's Theorem says for colorings <br />
C of pairs of natural numbers, there is an infinite set H such that <br />
all pairs from H have the same constant color. H is called a homogeneous <br />
set for C. What can we compute from H? If you are not sure, come to <br />
the talk and find out!<br />
<br />
=== Saulo Orizaga (Duke) ===<br />
<br />
Title: Introduction to phase field models and their efficient numerical implementation<br />
<br />
Abstract: In this talk we will provide an introduction to phase field models. We will focus in models<br />
related to the Cahn-Hilliard (CH) type of partial differential equation (PDE). We will discuss the<br />
challenges associated in solving such higher order parabolic problems. We will present several<br />
new numerical methods that are fast and efficient for solving CH or CH-extended type of problems.<br />
The new methods and their energy-stability properties will be discussed and tested with several computational examples commonly found in material science problems. If time allows, we will talk about more applications in which phase field models are useful and applicable.<br />
<br />
=== Caglar Uyanik (Yale) ===<br />
<br />
Title: Hausdorff dimension and gap distribution in billiards<br />
<br />
Abstract: A classical “unfolding” procedure allows one to turn questions about billiard trajectories in a Euclidean polygon into questions about the geodesic flow on a surface equipped with a certain geometric structure. Surprisingly, the flow on the surface is in turn related to the geodesic flow on the classical moduli spaces of Riemann surfaces. Building on recent breakthrough results of Eskin-Mirzakhani-Mohammadi, we prove a large deviations result for Birkhoff averages as well as generalize a classical theorem of Masur on geodesics in the moduli spaces of translation surfaces. <br />
<br />
=== Andy Zucker (Lyon) ===<br />
<br />
Title: Topological dynamics of countable groups and structures<br />
<br />
Abstract: We give an introduction to the abstract topological dynamics <br />
of topological groups, i.e. the study of the continuous actions of a <br />
topological group on a compact space. We are particularly interested <br />
in the minimal actions, those for which every orbit is dense. <br />
The study of minimal actions is aided by a classical theorem of Ellis, <br />
who proved that for any topological group G, there exists a universal <br />
minimal flow (UMF), a minimal G-action which factors onto every other <br />
minimal G-action. Here, we will focus on two classes of groups: <br />
a countable discrete group and the automorphism group of a countable <br />
first-order structure. In the case of a countable discrete group, <br />
Baire category methods can be used to show that the collection of <br />
minimal flows is quite rich and that the UMF is rather complicated. <br />
For an automorphism group G of a countable structure, combinatorial <br />
methods can be used to show that sometimes, the UMF is trivial, or <br />
equivalently that every continuous action of G on a compact space <br />
admits a global fixed point.<br />
<br />
=== Lillian Pierce (Duke) ===<br />
<br />
Title: On Bourgain’s counterexample for the Schrödinger maximal function<br />
<br />
Abstract: In 1980, Carleson asked a question in harmonic analysis: to which Sobolev space $H^s$ must an initial data function belong, for a pointwise a.e. convergence result to hold for the solution to the associated linear Schrödinger equation? Over the next decades, many people developed counterexamples to push the (necessary) range of s up, and positive results to push the (sufficient) range of s down. Now, these ranges are finally meeting: Bourgain’s 2016 counterexample showed s < n/(2(n+1)) fails, and Du and Zhang’s 2019 paper shows that s>n/(2(n+1)) suffices. <br />
In this talk, we will give an overview of how to rigorously derive Bourgain’s 2016 counterexample, based on simple facts from number theory. We will show how to build Bourgain’s counterexample starting from “zero knowledge," and how to gradually optimize the set-up to arrive at the final counterexample. The talk will be broadly accessible, particularly if we live up to the claim of starting from “zero knowledge.”<br />
<br />
=== Joe Kileel (Princeton) ===<br />
<br />
Title: Inverse Problems, Imaging and Tensor Decomposition<br />
<br />
Abstract: Perspectives from computational algebra and optimization are brought <br />
to bear on a scientific application and a data science application. <br />
In the first part of the talk, I will discuss cryo-electron microscopy <br />
(cryo-EM), an imaging technique to determine the 3-D shape of <br />
macromolecules from many noisy 2-D projections, recognized by the 2017 <br />
Chemistry Nobel Prize. Mathematically, cryo-EM presents a <br />
particularly rich inverse problem, with unknown orientations, extreme <br />
noise, big data and conformational heterogeneity. In particular, this <br />
motivates a general framework for statistical estimation under compact <br />
group actions, connecting information theory and group invariant <br />
theory. In the second part of the talk, I will discuss tensor rank <br />
decomposition, a higher-order variant of PCA broadly applicable in <br />
data science. A fast algorithm is introduced and analyzed, combining <br />
ideas of Sylvester and the power method.<br />
<br />
=== Cynthia Vinzant (NCSU) ===<br />
<br />
Title: Matroids, log-concavity, and expanders<br />
<br />
Abstract: Matroids are combinatorial objects that model various types of independence. They appear several fields mathematics, including graph theory, combinatorial optimization, and algebraic geometry. In this talk, I will introduce the theory of matroids along with the closely related class of polynomials called strongly log-concave polynomials. Strong log-concavity is a functional property of a real multivariate polynomial that translates to useful conditions on its coefficients. Discrete probability distributions defined by these coefficients inherit several of these nice properties. I will discuss the beautiful real and combinatorial geometry underlying these polynomials and describe applications to random walks on the faces of simplicial complexes. Consequences include proofs of Mason's conjecture that the sequence of numbers of independent sets of a matroid is ultra log-concave and the Mihail-Vazirani conjecture that the basis exchange graph of a matroid has expansion at least one. This is based on joint work with Nima Anari, Kuikui Liu, and Shayan Oveis Gharan.<br />
<br />
=== Jinzi Mac Huang (UCSD) ===<br />
<br />
Title: Mass transfer through fluid-structure interactions<br />
<br />
Abstract: The advancement of mathematics is closely associated with new discoveries from physical experiments. On one hand, mathematical tools like numerical simulation can help explain observations from experiments. On the other hand, experimental discoveries of physical phenomena, such as Brownian motion, can inspire the development of new mathematical approaches. In this talk, we focus on the interplay between applied math and experiments involving fluid-structure interactions -- a fascinating topic with both physical relevance and mathematical complexity. One such problem, inspired by geophysical fluid dynamics, is the experimental and numerical study of the dissolution of solid bodies in a fluid flow. The results of this study allow us to sketch mathematical answers to some long standing questions like the formation of stone forests in China and Madagascar, and how many licks it takes to get to the center of a Tootsie Pop. We will also talk about experimental math problems at the micro-scale, focusing on the mass transport process of diffusiophoresis, where colloidal particles are advected by a concentration gradient of salt solution. Exploiting this phenomenon, we see that colloids are able to navigate a micro-maze that has a salt concentration gradient across the exit and entry points. We further demonstrate that their ability to solve the maze is closely associated with the properties of a harmonic function – the salt concentration.<br />
<br />
=== William Chan (University of North Texas) ===<br />
<br />
Title: Definable infinitary combinatorics under determinacy<br />
<br />
Abstract: The axiom of determinacy, AD, states that in any infinite two player integer game of a certain form, one of the two players must have a winning strategy. It is incompatible with the ZFC set theory axioms with choice; however, it is a succinct extension of ZF which implies many subsets of the real line possess familiar regularity properties and eliminates many pathological sets. For instance, AD implies all sets of reals are Lebesgue measurable and every function from the reals to the reals is continuous on a comeager set. Determinacy also implies that the first uncountable cardinal has the strong partition property which can be used to define the partition measures. This talk will give an overview of the axiom of determinacy and will discuss recent results on the infinitary combinatorics surrounding the first uncountable cardinal and its partition measures. I will discuss the almost everywhere continuity phenomenon for functions outputting countable ordinals and the almost-everywhere uniformization results for closed and unbounded subsets of the first uncountable cardinal. These will be used to describe the rich structure of the cardinals below the powerset of the first and second uncountable cardinals under determinacy assumptions and to investigate the ultrapowers by these partition measures.<br />
<br />
== Future Colloquia ==<br />
[[Colloquia/Fall 2020| Fall 2020]]<br />
<br />
== Past Colloquia ==<br />
<br />
[[Colloquia/Blank|Blank]]<br />
<br />
[[Colloquia/Spring2019|Spring 2019]]<br />
<br />
[[Colloquia/Fall2018|Fall 2018]]<br />
<br />
[[Colloquia/Spring2018|Spring 2018]]<br />
<br />
[[Colloquia/Fall2017|Fall 2017]]<br />
<br />
[[Colloquia/Spring2017|Spring 2017]]<br />
<br />
[[Archived Fall 2016 Colloquia|Fall 2016]]<br />
<br />
[[Colloquia/Spring2016|Spring 2016]]<br />
<br />
[[Colloquia/Fall2015|Fall 2015]]<br />
<br />
[[Colloquia/Spring2014|Spring 2015]]<br />
<br />
[[Colloquia/Fall2014|Fall 2014]]<br />
<br />
[[Colloquia/Spring2014|Spring 2014]]<br />
<br />
[[Colloquia/Fall2013|Fall 2013]]<br />
<br />
[[Colloquia 2012-2013|Spring 2013]]<br />
<br />
[[Colloquia 2012-2013#Fall 2012|Fall 2012]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Colloquia/Spring2020&diff=18953Colloquia/Spring20202020-02-07T18:02:01Z<p>Spagnolie: /* Abstracts */</p>
<hr />
<div>= Mathematics Colloquium =<br />
<br />
All colloquia are on Fridays at 4:00 pm in Van Vleck B239, '''unless otherwise indicated'''.<br />
<br />
<br />
<br />
==Fall 2019==<br />
{| cellpadding="8"<br />
!align="left" | date <br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
|Sept 6 '''Room 911'''<br />
| Will Sawin (Columbia)<br />
| [[#Will Sawin (Columbia) | On Chowla's Conjecture over F_q[T] ]]<br />
| Marshall<br />
|-<br />
|Sept 13<br />
| [https://www.math.ksu.edu/~soibel/ Yan Soibelman] (Kansas State)<br />
|[[#Yan Soibelman (Kansas State)| Riemann-Hilbert correspondence and Fukaya categories ]]<br />
| Caldararu<br />
|<br />
|-<br />
|Sept 16 '''Monday Room 911'''<br />
| [http://mate.dm.uba.ar/~alidick/ Alicia Dickenstein] (Buenos Aires)<br />
|[[#Alicia Dickenstein (Buenos Aires)| Algebra and geometry in the study of enzymatic cascades ]]<br />
| Craciun<br />
|<br />
|-<br />
|Sept 20<br />
| [https://math.duke.edu/~jianfeng/ Jianfeng Lu] (Duke)<br />
|[[#Jianfeng Lu (Duke) | How to "localize" the computation?]]<br />
| Qin<br />
|<br />
|-<br />
|Sept 26 '''Thursday 3-4 pm Room 911'''<br />
| [http://eugeniacheng.com/ Eugenia Cheng] (School of the Art Institute of Chicago)<br />
| [[#Eugenia Cheng (School of the Art Institute of Chicago)| Character vs gender in mathematics and beyond ]]<br />
| Marshall / Friends of UW Madison Libraries<br />
|<br />
|-<br />
|Sept 27<br />
|<br />
|<br />
|-<br />
|Oct 4<br />
|<br />
|<br />
|-<br />
|Oct 11<br />
| Omer Mermelstein (Madison)<br />
| [[#Omer Mermelstein (Madison)| Generic flat pregeometries ]]<br />
|Andrews<br />
|<br />
|-<br />
|Oct 18<br />
| Shamgar Gurevich (Madison)<br />
| [[#Shamgar Gurevich (Madison) | Harmonic Analysis on GL(n) over Finite Fields ]]<br />
| Marshall<br />
|-<br />
|Oct 25<br />
|<br />
|-<br />
|Nov 1<br />
|Elchanan Mossel (MIT)<br />
|Distinguished Lecture<br />
|Roch<br />
|-<br />
|Nov 8<br />
|Jose Rodriguez (UW-Madison)<br />
|[[#Jose Rodriguez (UW-Madison) | Nearest Point Problems and Euclidean Distance Degrees]]<br />
|Erman<br />
|-<br />
|Nov 13 '''Wednesday 4-5pm'''<br />
|Ananth Shankar (MIT)<br />
|Exceptional splitting of abelian surfaces<br />
|-<br />
|Nov 20 '''Wednesday 4-5pm'''<br />
|Franca Hoffman (Caltech)<br />
|[[#Franca Hoffman (Caltech) | Gradient Flows: From PDE to Data Analysis]]<br />
|Smith<br />
|-<br />
|Nov 22<br />
| Jeffrey Danciger (UT Austin)<br />
| [[#Jeffrey Danciger (UT Austin) | "Affine geometry and the Auslander Conjecture"]]<br />
| Kent<br />
|-<br />
|Nov 25 '''Monday 4-5 pm Room 911'''<br />
|Tatyana Shcherbina (Princeton)<br />
| [[# Tatyana Shcherbina (Princeton)| "Random matrix theory and supersymmetry techniques"]]<br />
|Roch<br />
|-<br />
|Nov 29<br />
|Thanksgiving<br />
|<br />
|-<br />
|Dec 2 '''Monday 4-5pm'''<br />
|Tingran Gao (University of Chicago)<br />
| [[#Tingran Gao (University of Chicago)| "Manifold Learning on Fibre Bundles"]]<br />
|Smith<br />
|-<br />
|Dec 4 '''Wednesday 4-5 pm Room 911'''<br />
|Andrew Zimmer (LSU)<br />
|[[#Andrew Zimmer (LSU)| "Intrinsic and extrinsic geometries in several complex variables"]]<br />
|Gong<br />
|-<br />
|Dec 6<br />
|Charlotte Chan (MIT)<br />
|[[#Charlotte Chan (MIT)|"Flag varieties and representations of p-adic groups"]]<br />
|Erman<br />
|-<br />
|Dec 9 '''Monday 4-5 pm'''<br />
|Hui Yu (Columbia)<br />
|[[#Hui Yu (Columbia)|Singular sets in obstacle problems]]<br />
|Tran<br />
|-<br />
|Dec 11 '''Wednesday 2:30-3:30pm Room 911'''<br />
|Alex Waldron (Michigan)<br />
|[[#Alex Waldron (Michigan)|Gauge theory and geometric flows]]<br />
|Paul<br />
|-<br />
|Dec 11 '''Wednesday 4-5pm'''<br />
|Nick Higham (Manchester)<br />
|[[#Nick Higham (Manchester)|LAA lecture: Challenges in Multivalued Matrix Functions]]<br />
|Brualdi<br />
|-<br />
|Dec 13 <br />
|Chenxi Wu (Rutgers)<br />
|[[#Chenxi Wu (Rutgers)|Kazhdan's theorem on metric graphs]]<br />
|Ellenberg<br />
|-<br />
|Dec 18 '''Wednesday 4-5pm'''<br />
|Ruobing Zhang (Stony Brook)<br />
|[[#Ruobing Zhang (Stony Brook)|Geometry and analysis of degenerating Calabi-Yau manifolds]]<br />
|Paul<br />
|-<br />
|}<br />
<br />
==Spring 2020==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date <br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|<br />
|-<br />
|Jan 10<br />
|Thomas Lam (Michigan) <br />
|[[#Thomas Lam (Michigan) |Positive geometries and string theory amplitudes]]<br />
|Erman<br />
|-<br />
|Jan 21 '''Tuesday 4-5 pm in B139'''<br />
|[http://www.nd.edu/~cholak/ Peter Cholak] (Notre Dame) <br />
|[[#Peter Cholak (Notre Dame) |What can we compute from solutions to combinatorial problems?]]<br />
|Lempp<br />
|-<br />
|Jan 24<br />
|[https://math.duke.edu/people/saulo-orizaga Saulo Orizaga] (Duke)<br />
|[[#Saulo Orizaga (Duke) | Introduction to phase field models and their efficient numerical implementation ]]<br />
|<br />
|-<br />
|Jan 27 '''Monday 4-5 pm in 911'''<br />
|[https://math.yale.edu/people/caglar-uyanik Caglar Uyanik] (Yale)<br />
|[[#Caglar Uyanik (Yale) | Hausdorff dimension and gap distribution in billiards ]]<br />
|Ellenberg<br />
|-<br />
|Jan 29 '''Wednesday 4-5 pm'''<br />
|[https://ajzucker.wordpress.com/ Andy Zucker] (Lyon)<br />
|[[#Andy Zucker (Lyon) |Topological dynamics of countable groups and structures]]<br />
|Soskova/Lempp<br />
|-<br />
|Jan 31 <br />
|[https://services.math.duke.edu/~pierce/ Lillian Pierce] (Duke)<br />
|[[#Lillian Pierce (Duke) |On Bourgain’s counterexample for the Schrödinger maximal function]]<br />
|Marshall/Seeger<br />
|-<br />
|Feb 7<br />
|[https://web.math.princeton.edu/~jkileel/ Joe Kileel] (Princeton)<br />
|[[#Joe Kileel (Princeton) |Inverse Problems, Imaging and Tensor Decomposition]]<br />
|Roch<br />
|-<br />
|Feb 10<br />
|[https://clvinzan.math.ncsu.edu/ Cynthia Vinzant] (NCSU)<br />
|[[#Cynthia Vinzant (NCSU) |Matroids, log-concavity, and expanders]]<br />
|Roch/Erman<br />
|-<br />
|Feb 12 '''Wednesday 4-5 pm in VV 911'''<br />
|[https://www.machuang.org/ Jinzi Mac Huang] (UCSD)<br />
|[[#Jinzi Mac Huang (UCSD) |Mass transfer through fluid-structure interactions]]<br />
|Spagnolie<br />
|-<br />
|Feb 14<br />
|[https://math.unt.edu/people/william-chan/ William Chan] (University of North Texas)<br />
|[[#William Chan (University of North Texas) |Definable infinitary combinatorics under determinacy]]<br />
|Soskova/Lempp<br />
|-<br />
|Feb 17<br />
|[https://yisun.io/ Yi Sun] (Columbia)<br />
|[[#Yi Sun (Columbia) |TBA]]<br />
|Roch<br />
|-<br />
|Feb 21<br />
|Shai Evra (IAS)<br />
|<br />
|Gurevich<br />
|<br />
|-<br />
|Feb 28<br />
|Brett Wick (Washington University, St. Louis)<br />
|<br />
|Seeger<br />
|-<br />
|March 6<br />
| Jessica Fintzen (Michigan)<br />
|<br />
|Marshall<br />
|-<br />
|March 13<br />
|<br />
|-<br />
|March 20<br />
|Spring break<br />
|<br />
|-<br />
|March 27<br />
|(Moduli Spaces Conference)<br />
|<br />
|Boggess, Sankar<br />
|-<br />
|April 3<br />
|Caroline Turnage-Butterbaugh (Carleton College)<br />
|<br />
|Marshall<br />
|-<br />
|April 10<br />
| Sarah Koch (Michigan)<br />
|<br />
| Bruce (WIMAW)<br />
|-<br />
|April 17<br />
|<br />
|<br />
|<br />
|-<br />
|April 23<br />
|Martin Hairer (Imperial College London)<br />
|Wolfgang Wasow Lecture<br />
|Hao Shen<br />
|-<br />
|April 24<br />
|Natasa Sesum (Rutgers University)<br />
|<br />
|Angenent<br />
|-<br />
|May 1<br />
|Robert Lazarsfeld (Stony Brook)<br />
|Distinguished lecture<br />
|Erman<br />
|}<br />
<br />
== Abstracts ==<br />
<br />
<br />
===Will Sawin (Columbia)===<br />
<br />
Title: On Chowla's Conjecture over F_q[T]<br />
<br />
Abstract: The Mobius function in number theory is a sequences of 1s, <br />
-1s, and 0s, which is simple to define and closely related to the <br />
prime numbers. Its behavior seems highly random. Chowla's conjecture <br />
is one precise formalization of this randomness, and has seen recent <br />
work by Matomaki, Radziwill, Tao, and Teravainen making progress on <br />
it. In joint work with Mark Shusterman, we modify this conjecture by <br />
replacing the natural numbers parameterizing this sequence with <br />
polynomials over a finite field. Under mild conditions on the finite <br />
field, we are able to prove a strong form of this conjecture. The <br />
proof is based on taking a geometric perspective on the problem, and <br />
succeeds because we are able to simplify the geometry using a trick <br />
based on the strange properties of polynomial derivatives over finite <br />
fields.<br />
<br />
<br />
===Yan Soibelman (Kansas State)===<br />
<br />
Title: Riemann-Hilbert correspondence and Fukaya categories<br />
<br />
Abstract: In this talk I am going to discuss the role of Fukaya categories in the Riemann-Hilbert correspondence<br />
for differential, q-difference and elliptic difference equations in dimension one.<br />
This approach not only gives a unified answer for several versions of the Riemann-Hilbert correspondence but also leads to a natural formulation<br />
of the non-abelian Hodge theory in dimension one. It also explains why periodic monopoles<br />
should appear as harmonic objects in this generalized non-abelian Hodge theory.<br />
All that is a part of the bigger project ``Holomorphic Floer theory",<br />
joint with Maxim Kontsevich.<br />
<br />
<br />
===Alicia Dickenstein (Buenos Aires)===<br />
<br />
Title: Algebra and geometry in the study of enzymatic cascades<br />
<br />
Abstract: In recent years, techniques from computational and real algebraic geometry have been successfully used to address mathematical challenges in systems biology. The algebraic theory of chemical reaction systems aims to understand their dynamic behavior by taking advantage of the inherent algebraic structure in the kinetic equations, and does not need the determination of the parameters a priori, which can be theoretically or practically impossible.<br />
I will give a gentle introduction to general results based on the network structure. In particular, I will describe a general framework for biological systems, called MESSI systems, that describe Modifications of type Enzyme-Substrate or Swap with Intermediates, and include many networks that model post-translational modifications of proteins inside the cell. I will also outline recent methods to address the important question of multistationarity, in particular in the study of enzymatic cascades, and will point out some of the mathematical challenges that arise from this application.<br />
<br />
<br />
=== Jianfeng Lu (Duke) ===<br />
Title: How to ``localize" the computation?<br />
<br />
It is often desirable to restrict the numerical computation to a local region to achieve best balance between accuracy and affordability in scientific computing. It is important to avoid artifacts and guarantee predictable modelling while artificial boundary conditions have to be introduced to restrict the computation. In this talk, we will discuss some recent understanding on how to achieve such local computation in the context of topological edge states and elliptic random media.<br />
<br />
<br />
===Eugenia Cheng (School of the Art Institute of Chicago)===<br />
<br />
Title: Character vs gender in mathematics and beyond<br />
<br />
Abstract: This presentation will be based on my experience of being a female mathematician, and teaching mathematics at all levels from elementary school to grad school. The question of why women are under-represented in mathematics is complex and there are no simple answers, only many many contributing factors. I will focus on character traits, and argue that if we focus on this rather than gender we can have a more productive and less divisive conversation. To try and focus on characters rather than genders I will introduce gender-neutral character adjectives "ingressive" and "congressive" to replace masculine and feminine. I will share my experience of teaching congressive abstract mathematics to art students, in a congressive way, and the possible effects this could have for everyone in mathematics, not just women.<br />
<br />
<br />
===Omer Mermelstein (Madison)===<br />
<br />
Title: Generic flat pregeometries<br />
<br />
Abstract: In model theory, the tamest of structures are the strongly minimal ones -- those in which every equation in a single variable has either finitely many or cofinitely many solution. Algebraically closed fields and vector spaces are the canonical examples. Zilber’s conjecture, later refuted by Hrushovski, states that the source of geometric complexity in a strongly minimal structure must be algebraic. The property of "flatness" (strict gammoid) of a geometry (matroid) is that which guarantees Hrushovski's construction is devoid of any associative structure.<br />
The majority of the talk will explain what flatness is, how it should be thought of, and how closely it relates to hypergraphs and Hrushovski's construction method. Model theory makes an appearance only in the second part, where I will share results pertaining to the specific family of geometries arising from Hrushovski's methods.<br />
<br />
<br />
===Shamgar Gurevich (Madison)===<br />
<br />
Title: Harmonic Analysis on GL(n) over Finite Fields.<br />
<br />
Abstract: There are many formulas that express interesting properties of a finite group G in terms of sums over its characters. For evaluating or estimating these sums, one of the most salient quantities to understand is the character ratio:<br />
<br />
trace(ρ(g)) / dim(ρ),<br />
<br />
for an irreducible representation ρ of G and an element g of G. For example, Diaconis and Shahshahani stated a formula of the mentioned type for analyzing certain random walks on G.<br />
<br />
Recently, we discovered that for classical groups G over finite fields there is a natural invariant of representations that provides strong information on the character ratio. We call this invariant rank. <br />
<br />
This talk will discuss the notion of rank for the group GLn over finite fields, demonstrate how it controls the character ratio, and explain how one can apply the results to verify mixing time and rate for certain random walks.<br />
<br />
This is joint work with Roger Howe (Yale and Texas AM). The numerics for this work was carried by Steve Goldstein (Madison)<br />
<br />
<br />
===Jose Rodriguez (UW-Madison)===<br />
<br />
Abstract: Determining the closest point to a model (subset of Euclidean space) is an important problem in many applications in science,<br />
engineering, and statistics. One way to solve this problem is by minimizing the squared Euclidean distance function using a gradient<br />
descent approach. However, when there are multiple local minima, there is no guarantee of convergence to the true global minimizer.<br />
An alternative method is to determine the critical points of an objective function on the model.<br />
In algebraic statistics, the models of interest are algebraic sets, i.e., solution sets to a system of multivariate polynomial equations. In this situation, the number of critical points of the squared Euclidean distance function on the model’s Zariski closure is a topological invariant called the Euclidean distance degree (ED degree).<br />
In this talk, I will present some models from computer vision and statistics that may be described as algebraic sets. Moreover,<br />
I will describe a topological method for determining a Euclidean distance degree and a numerical algebraic geometry approach for<br />
determining critical points of the squared Euclidean distance function.<br />
<br />
<br />
===Ananth Shankar (MIT)===<br />
<br />
Abstract: An abelian surface 'splits' if it admits a non-trivial map to some elliptic curve. It is well known that the set of abelian surfaces that split are sparse in the set of all abelian surfaces. Nevertheless, we prove that there are infinitely many split abelian surfaces in arithmetic one-parameter families of generically non-split abelian surfaces. I will describe this work, and if time permits, mention generalizations of this result to the setting of K3 surfaces, as well as applications to the dynamics of hecke orbits. This is joint work with Tang, Maulik-Tang, and Shankar-Tang-Tayou.<br />
<br />
<br />
===Franca Hoffman (Caltech)===<br />
<br />
Title: Gradient Flows: From PDE to Data Analysis.<br />
<br />
Abstract: Certain diffusive PDEs can be viewed as infinite-dimensional gradient flows. This fact has led to the development of new tools in various areas of mathematics ranging from PDE theory to data science. In this talk, we focus on two different directions: model-driven approaches and data-driven approaches.<br />
In the first part of the talk we use gradient flows for analyzing non-linear and non-local aggregation-diffusion equations when the corresponding energy functionals are not necessarily convex. Moreover, the gradient flow structure enables us to make connections to well-known functional inequalities, revealing possible links between the optimizers of these inequalities and the equilibria of certain aggregation-diffusion PDEs.<br />
In the second part, we use and develop gradient flow theory to design novel tools for data analysis. We draw a connection between gradient flows and Ensemble Kalman methods for parameter estimation. We introduce the Ensemble Kalman Sampler - a derivative-free methodology for model calibration and uncertainty quantification in expensive black-box models. The interacting particle dynamics underlying our algorithm can be approximated by a novel gradient flow structure in a modified Wasserstein metric which reflects particle correlations. The geometry of this modified Wasserstein metric is of independent theoretical interest.<br />
<br />
<br />
=== Jeffrey Danciger (UT Austin) ===<br />
<br />
Title: Affine geometry and the Auslander Conjecture<br />
<br />
Abstract: The Auslander Conjecture is an analogue of Bieberbach’s theory of Euclidean crystallographic groups in the setting of affine geometry. It predicts that a complete affine manifold (a manifold equipped with a complete torsion-free flat affine connection) which is compact must have virtually solvable fundamental group. The conjecture is known up to dimension six, but is known to fail if the compactness assumption is removed, even in low dimensions. We discuss some history of this conjecture, give some basic examples, and then survey some recent advances in the study of non-compact complete affine manifolds with non-solvable fundamental group. <br />
Tools from the deformation theory of pseudo-Riemannian hyperbolic manifolds and also from higher Teichm&uuml;ller theory will enter the picture.<br />
<br />
<br />
=== Tatyana Shcherbina (Princeton) ===<br />
<br />
Title: Random matrix theory and supersymmetry techniques<br />
<br />
Abstract: Starting from the works of Erdos, Yau, Schlein with coauthors, the significant progress in understanding the universal behavior of many random graph and random matrix models were achieved. However for the random matrices with a special structure our understanding is still very limited. In this talk I am going to overview applications of another approach to the study of the local eigenvalues statistics in random matrix theory based on so-called supersymmetry techniques (SUSY). SUSY approach is based on the representation of the determinant as an integral over the Grassmann (anticommuting) variables. Combining this representation with the representation of an inverse determinant as an integral over the Gaussian complex field, SUSY allows to obtain an integral representation for the main spectral characteristics of random matrices such as limiting density, correlation functions, the resolvent's elements, etc. This method is widely (and successfully) used in the physics literature and is potentially very powerful but the rigorous control of the integral representations, which can be obtained by this method, is quite difficult, and it requires powerful analytic and statistical mechanics tools. In this talk we will discuss some recent progress in application of SUSY to the analysis of local spectral characteristics of the prominent ensemble of random band matrices, i.e. random matrices<br />
whose entries become negligible if their distance from the main diagonal exceeds a certain parameter called the band width. <br />
<br />
<br />
=== Tingran Gao (University of Chicago) ===<br />
<br />
Title: Manifold Learning on Fibre Bundles<br />
<br />
Abstract: Spectral geometry has played an important role in modern geometric data analysis, where the technique is widely known as Laplacian eigenmaps or diffusion maps. In this talk, we present a geometric framework that studies graph representations of complex datasets, where each edge of the graph is equipped with a non-scalar transformation or correspondence. This new framework models such a dataset as a fibre bundle with a connection, and interprets the collection of pairwise functional relations as defining a horizontal diffusion process on the bundle driven by its projection on the base. The eigenstates of this horizontal diffusion process encode the “consistency” among objects in the dataset, and provide a lens through which the geometry of the dataset can be revealed. We demonstrate an application of this geometric framework on evolutionary anthropology.<br />
<br />
<br />
=== Andrew Zimmer (LSU) ===<br />
<br />
Title: Intrinsic and extrinsic geometries in several complex variables<br />
<br />
Abstract: A bounded domain in complex Euclidean space, despite being one of the simplest types of manifolds, has a number of interesting geometric structures. When the domain is pseudoconvex, it has a natural intrinsic geometry: the complete Kaehler-Einstein metric constructed by Cheng-Yau and Mok-Yau. When the domain is smoothly bounded, there is also a natural extrinsic structure: the CR-geometry of the boundary. In this talk, I will describe connections between these intrinsic and extrinsic geometries. Then, I will discuss how these connections can lead to new analytic results.<br />
<br />
=== Charlotte Chan (MIT) ===<br />
<br />
Title: Flag varieties and representations of p-adic groups<br />
<br />
Abstract: In the 1950s, Borel, Weil, and Bott showed that the<br />
irreducible representations of a complex reductive group can be<br />
realized in the cohomology of line bundles on flag varieties. In the<br />
1970s, Deligne and Lusztig constructed a family of subvarieties of<br />
flag varieties whose cohomology realizes the irreducible<br />
representations of reductive groups over finite fields. I will survey<br />
these stories, explain recent progress towards finding geometric<br />
constructions of representations of p-adic groups, and discuss<br />
interactions with the Langlands program.<br />
<br />
=== Hui Yu (Columbia) ===<br />
<br />
Title: Singular sets in obstacle problems<br />
<br />
Abstract: One of the most important free boundary problems is the obstacle problem. The regularity of its free boundary has been studied for over half a century. In this talk, we review some classical results as well as exciting new developments. In particular, we discuss the recent resolution of the regularity of the singular set for the fully nonlinear obstacle problem. This talk is based on a joint work with Ovidiu Savin at Columbia University.<br />
<br />
=== Alex Waldron (Michigan) ===<br />
<br />
Title: Gauge theory and geometric flows<br />
<br />
Abstract: I will give a brief introduction to two major areas of research in differential geometry: gauge theory and geometric flows. I'll then introduce a geometric flow (Yang-Mills flow) arising from a variational problem with origins in physics, which has been studied by geometric analysts since the early 1980s. I'll conclude by discussing my own work on the behavior of Yang-Mills flow in the critical dimension (n = 4).<br />
<br />
=== Nick Higham (Manchester) ===<br />
<br />
Title: Challenges in Multivalued Matrix Functions<br />
<br />
Abstract: In this lecture I will discuss multivalued matrix functions that arise in solving various kinds of matrix equations. The matrix logarithm is the prototypical example, and my first interaction with Hans Schneider was about this function. Another example is the Lambert W function of a matrix, which is much less well known but has been attracting recent interest. A theme of the talk is the importance of choosing appropriate principal values and making sure that the correct choices of signs and branches are used,<br />
both in theory and in computation. I will give examples where incorrect results have previously been obtained.<br />
<br />
I focus on matrix inverse trigonometric and inverse hyperbolic functions, beginning by investigating existence and characterization. Turning to the principal values, various functional identities are derived, some of which are new even in the scalar case, including a “round trip” formula that relates acos(cos A) to A and similar formulas for the other inverse functions. Key tools used in the derivations are the matrix unwinding function and the matrix sign function.<br />
<br />
A new inverse scaling and squaring type algorithm employing a Schur decomposition and variable-degree Pade approximation is derived for computing acos, and it is shown how it can also be used to compute asin, acosh, and asinh.<br />
<br />
=== Chenxi Wu (Rutgers) ===<br />
<br />
Title: Kazhdan's theorem on metric graphs<br />
<br />
Abstract: I will give an introduction to the concept of canonical (arakelov) metric on a metric graph, which is related to combinatorial questions like the counting of spanning trees, and generalizes the corresponding concept on Riemann surfaces. I will also present a recent result in collaboration with Farbod Shokrieh on the convergence of canonical metric under normal covers.<br />
<br />
=== Ruobing Zhang (Stony Brook) ===<br />
<br />
Title: Geometry and analysis of degenerating Calabi-Yau manifolds<br />
<br />
Abstract: This talk concerns a naturally occurring family of degenerating Calabi-Yau manifolds. A primary tool in analyzing their behavior is to combine the recently developed structure theory for Einstein manifolds and multi-scale singularity analysis for degenerating nonlinear PDEs in the collapsed setting. Based on the algebraic degeneration, we will give precise and more quantitative descriptions of singularity formation from both metric and analytic points of view.<br />
<br />
=== Thomas Lam (Michigan) === <br />
<br />
Title: Positive geometries and string theory amplitudes<br />
<br />
Abstract: Inspired by developments in quantum field theory, we<br />
recently defined the notion of a positive geometry, a class of spaces<br />
that includes convex polytopes, positive parts of projective toric<br />
varieties, and positive parts of flag varieties. I will discuss some<br />
basic features of the theory and an application to genus zero string<br />
theory amplitudes. As a special case, we obtain the Euler beta<br />
function, familiar to mathematicians, as the "stringy canonical form"<br />
of the closed interval.<br />
<br />
This talk is based on joint work with Arkani-Hamed, Bai, and He.<br />
<br />
=== Peter Cholak (Notre Dame) ===<br />
<br />
Title: What can we compute from solutions to combinatorial problems?<br />
<br />
Abstract: This will be an introductory talk to an exciting current <br />
research area in mathematical logic. Mostly we are interested in <br />
solutions to Ramsey's Theorem. Ramsey's Theorem says for colorings <br />
C of pairs of natural numbers, there is an infinite set H such that <br />
all pairs from H have the same constant color. H is called a homogeneous <br />
set for C. What can we compute from H? If you are not sure, come to <br />
the talk and find out!<br />
<br />
=== Saulo Orizaga (Duke) ===<br />
<br />
Title: Introduction to phase field models and their efficient numerical implementation<br />
<br />
Abstract: In this talk we will provide an introduction to phase field models. We will focus in models<br />
related to the Cahn-Hilliard (CH) type of partial differential equation (PDE). We will discuss the<br />
challenges associated in solving such higher order parabolic problems. We will present several<br />
new numerical methods that are fast and efficient for solving CH or CH-extended type of problems.<br />
The new methods and their energy-stability properties will be discussed and tested with several computational examples commonly found in material science problems. If time allows, we will talk about more applications in which phase field models are useful and applicable.<br />
<br />
=== Caglar Uyanik (Yale) ===<br />
<br />
Title: Hausdorff dimension and gap distribution in billiards<br />
<br />
Abstract: A classical “unfolding” procedure allows one to turn questions about billiard trajectories in a Euclidean polygon into questions about the geodesic flow on a surface equipped with a certain geometric structure. Surprisingly, the flow on the surface is in turn related to the geodesic flow on the classical moduli spaces of Riemann surfaces. Building on recent breakthrough results of Eskin-Mirzakhani-Mohammadi, we prove a large deviations result for Birkhoff averages as well as generalize a classical theorem of Masur on geodesics in the moduli spaces of translation surfaces. <br />
<br />
=== Andy Zucker (Lyon) ===<br />
<br />
Title: Topological dynamics of countable groups and structures<br />
<br />
Abstract: We give an introduction to the abstract topological dynamics <br />
of topological groups, i.e. the study of the continuous actions of a <br />
topological group on a compact space. We are particularly interested <br />
in the minimal actions, those for which every orbit is dense. <br />
The study of minimal actions is aided by a classical theorem of Ellis, <br />
who proved that for any topological group G, there exists a universal <br />
minimal flow (UMF), a minimal G-action which factors onto every other <br />
minimal G-action. Here, we will focus on two classes of groups: <br />
a countable discrete group and the automorphism group of a countable <br />
first-order structure. In the case of a countable discrete group, <br />
Baire category methods can be used to show that the collection of <br />
minimal flows is quite rich and that the UMF is rather complicated. <br />
For an automorphism group G of a countable structure, combinatorial <br />
methods can be used to show that sometimes, the UMF is trivial, or <br />
equivalently that every continuous action of G on a compact space <br />
admits a global fixed point.<br />
<br />
=== Lillian Pierce (Duke) ===<br />
<br />
Title: On Bourgain’s counterexample for the Schrödinger maximal function<br />
<br />
Abstract: In 1980, Carleson asked a question in harmonic analysis: to which Sobolev space $H^s$ must an initial data function belong, for a pointwise a.e. convergence result to hold for the solution to the associated linear Schrödinger equation? Over the next decades, many people developed counterexamples to push the (necessary) range of s up, and positive results to push the (sufficient) range of s down. Now, these ranges are finally meeting: Bourgain’s 2016 counterexample showed s < n/(2(n+1)) fails, and Du and Zhang’s 2019 paper shows that s>n/(2(n+1)) suffices. <br />
In this talk, we will give an overview of how to rigorously derive Bourgain’s 2016 counterexample, based on simple facts from number theory. We will show how to build Bourgain’s counterexample starting from “zero knowledge," and how to gradually optimize the set-up to arrive at the final counterexample. The talk will be broadly accessible, particularly if we live up to the claim of starting from “zero knowledge.”<br />
<br />
=== Joe Kileel (Princeton) ===<br />
<br />
Title: Inverse Problems, Imaging and Tensor Decomposition<br />
<br />
Abstract: Perspectives from computational algebra and optimization are brought <br />
to bear on a scientific application and a data science application. <br />
In the first part of the talk, I will discuss cryo-electron microscopy <br />
(cryo-EM), an imaging technique to determine the 3-D shape of <br />
macromolecules from many noisy 2-D projections, recognized by the 2017 <br />
Chemistry Nobel Prize. Mathematically, cryo-EM presents a <br />
particularly rich inverse problem, with unknown orientations, extreme <br />
noise, big data and conformational heterogeneity. In particular, this <br />
motivates a general framework for statistical estimation under compact <br />
group actions, connecting information theory and group invariant <br />
theory. In the second part of the talk, I will discuss tensor rank <br />
decomposition, a higher-order variant of PCA broadly applicable in <br />
data science. A fast algorithm is introduced and analyzed, combining <br />
ideas of Sylvester and the power method.<br />
<br />
=== Cynthia Vinzant (NCSU) ===<br />
<br />
Title: Matroids, log-concavity, and expanders<br />
<br />
Abstract: Matroids are combinatorial objects that model various types of independence. They appear several fields mathematics, including graph theory, combinatorial optimization, and algebraic geometry. In this talk, I will introduce the theory of matroids along with the closely related class of polynomials called strongly log-concave polynomials. Strong log-concavity is a functional property of a real multivariate polynomial that translates to useful conditions on its coefficients. Discrete probability distributions defined by these coefficients inherit several of these nice properties. I will discuss the beautiful real and combinatorial geometry underlying these polynomials and describe applications to random walks on the faces of simplicial complexes. Consequences include proofs of Mason's conjecture that the sequence of numbers of independent sets of a matroid is ultra log-concave and the Mihail-Vazirani conjecture that the basis exchange graph of a matroid has expansion at least one. This is based on joint work with Nima Anari, Kuikui Liu, and Shayan Oveis Gharan.<br />
<br />
=== Jinz Mac Huang (UCSD) ===<br />
<br />
Title: Mass transfer through fluid-structure interactions<br />
<br />
Abstract: The advancement of mathematics is closely associated with new discoveries from physical experiments. On one hand, mathematical tools like numerical simulation can help explain observations from experiments. On the other hand, experimental discoveries of physical phenomena, such as Brownian motion, can inspire the development of new mathematical approaches. In this talk, we focus on the interplay between applied math and experiments involving fluid-structure interactions -- a fascinating topic with both physical relevance and mathematical complexity. One such problem, inspired by geophysical fluid dynamics, is the experimental and numerical study of the dissolution of solid bodies in a fluid flow. The results of this study allow us to sketch mathematical answers to some long standing questions like the formation of stone forests in China and Madagascar, and how many licks it takes to get to the center of a Tootsie Pop. We will also talk about experimental math problems at the micro-scale, focusing on the mass transport process of diffusiophoresis, where colloidal particles are advected by a concentration gradient of salt solution. Exploiting this phenomenon, we see that colloids are able to navigate a micro-maze that has a salt concentration gradient across the exit and entry points. We further demonstrate that their ability to solve the maze is closely associated with the properties of a harmonic function – the salt concentration.<br />
<br />
=== William Chan (University of North Texas) ===<br />
<br />
Title: Definable infinitary combinatorics under determinacy<br />
<br />
Abstract: The axiom of determinacy, AD, states that in any infinite two player integer game of a certain form, one of the two players must have a winning strategy. It is incompatible with the ZFC set theory axioms with choice; however, it is a succinct extension of ZF which implies many subsets of the real line possess familiar regularity properties and eliminates many pathological sets. For instance, AD implies all sets of reals are Lebesgue measurable and every function from the reals to the reals is continuous on a comeager set. Determinacy also implies that the first uncountable cardinal has the strong partition property which can be used to define the partition measures. This talk will give an overview of the axiom of determinacy and will discuss recent results on the infinitary combinatorics surrounding the first uncountable cardinal and its partition measures. I will discuss the almost everywhere continuity phenomenon for functions outputting countable ordinals and the almost-everywhere uniformization results for closed and unbounded subsets of the first uncountable cardinal. These will be used to describe the rich structure of the cardinals below the powerset of the first and second uncountable cardinals under determinacy assumptions and to investigate the ultrapowers by these partition measures.<br />
<br />
== Future Colloquia ==<br />
[[Colloquia/Fall 2020| Fall 2020]]<br />
<br />
== Past Colloquia ==<br />
<br />
[[Colloquia/Blank|Blank]]<br />
<br />
[[Colloquia/Spring2019|Spring 2019]]<br />
<br />
[[Colloquia/Fall2018|Fall 2018]]<br />
<br />
[[Colloquia/Spring2018|Spring 2018]]<br />
<br />
[[Colloquia/Fall2017|Fall 2017]]<br />
<br />
[[Colloquia/Spring2017|Spring 2017]]<br />
<br />
[[Archived Fall 2016 Colloquia|Fall 2016]]<br />
<br />
[[Colloquia/Spring2016|Spring 2016]]<br />
<br />
[[Colloquia/Fall2015|Fall 2015]]<br />
<br />
[[Colloquia/Spring2014|Spring 2015]]<br />
<br />
[[Colloquia/Fall2014|Fall 2014]]<br />
<br />
[[Colloquia/Spring2014|Spring 2014]]<br />
<br />
[[Colloquia/Fall2013|Fall 2013]]<br />
<br />
[[Colloquia 2012-2013|Spring 2013]]<br />
<br />
[[Colloquia 2012-2013#Fall 2012|Fall 2012]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Colloquia/Spring2020&diff=18874Colloquia/Spring20202020-02-03T17:48:54Z<p>Spagnolie: /* Spring 2020 */</p>
<hr />
<div>= Mathematics Colloquium =<br />
<br />
All colloquia are on Fridays at 4:00 pm in Van Vleck B239, '''unless otherwise indicated'''.<br />
<br />
<br />
<br />
==Fall 2019==<br />
{| cellpadding="8"<br />
!align="left" | date <br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
|Sept 6 '''Room 911'''<br />
| Will Sawin (Columbia)<br />
| [[#Will Sawin (Columbia) | On Chowla's Conjecture over F_q[T] ]]<br />
| Marshall<br />
|-<br />
|Sept 13<br />
| [https://www.math.ksu.edu/~soibel/ Yan Soibelman] (Kansas State)<br />
|[[#Yan Soibelman (Kansas State)| Riemann-Hilbert correspondence and Fukaya categories ]]<br />
| Caldararu<br />
|<br />
|-<br />
|Sept 16 '''Monday Room 911'''<br />
| [http://mate.dm.uba.ar/~alidick/ Alicia Dickenstein] (Buenos Aires)<br />
|[[#Alicia Dickenstein (Buenos Aires)| Algebra and geometry in the study of enzymatic cascades ]]<br />
| Craciun<br />
|<br />
|-<br />
|Sept 20<br />
| [https://math.duke.edu/~jianfeng/ Jianfeng Lu] (Duke)<br />
|[[#Jianfeng Lu (Duke) | How to "localize" the computation?]]<br />
| Qin<br />
|<br />
|-<br />
|Sept 26 '''Thursday 3-4 pm Room 911'''<br />
| [http://eugeniacheng.com/ Eugenia Cheng] (School of the Art Institute of Chicago)<br />
| [[#Eugenia Cheng (School of the Art Institute of Chicago)| Character vs gender in mathematics and beyond ]]<br />
| Marshall / Friends of UW Madison Libraries<br />
|<br />
|-<br />
|Sept 27<br />
|<br />
|<br />
|-<br />
|Oct 4<br />
|<br />
|<br />
|-<br />
|Oct 11<br />
| Omer Mermelstein (Madison)<br />
| [[#Omer Mermelstein (Madison)| Generic flat pregeometries ]]<br />
|Andrews<br />
|<br />
|-<br />
|Oct 18<br />
| Shamgar Gurevich (Madison)<br />
| [[#Shamgar Gurevich (Madison) | Harmonic Analysis on GL(n) over Finite Fields ]]<br />
| Marshall<br />
|-<br />
|Oct 25<br />
|<br />
|-<br />
|Nov 1<br />
|Elchanan Mossel (MIT)<br />
|Distinguished Lecture<br />
|Roch<br />
|-<br />
|Nov 8<br />
|Jose Rodriguez (UW-Madison)<br />
|[[#Jose Rodriguez (UW-Madison) | Nearest Point Problems and Euclidean Distance Degrees]]<br />
|Erman<br />
|-<br />
|Nov 13 '''Wednesday 4-5pm'''<br />
|Ananth Shankar (MIT)<br />
|Exceptional splitting of abelian surfaces<br />
|-<br />
|Nov 20 '''Wednesday 4-5pm'''<br />
|Franca Hoffman (Caltech)<br />
|[[#Franca Hoffman (Caltech) | Gradient Flows: From PDE to Data Analysis]]<br />
|Smith<br />
|-<br />
|Nov 22<br />
| Jeffrey Danciger (UT Austin)<br />
| [[#Jeffrey Danciger (UT Austin) | "Affine geometry and the Auslander Conjecture"]]<br />
| Kent<br />
|-<br />
|Nov 25 '''Monday 4-5 pm Room 911'''<br />
|Tatyana Shcherbina (Princeton)<br />
| [[# Tatyana Shcherbina (Princeton)| "Random matrix theory and supersymmetry techniques"]]<br />
|Roch<br />
|-<br />
|Nov 29<br />
|Thanksgiving<br />
|<br />
|-<br />
|Dec 2 '''Monday 4-5pm'''<br />
|Tingran Gao (University of Chicago)<br />
| [[#Tingran Gao (University of Chicago)| "Manifold Learning on Fibre Bundles"]]<br />
|Smith<br />
|-<br />
|Dec 4 '''Wednesday 4-5 pm Room 911'''<br />
|Andrew Zimmer (LSU)<br />
|[[#Andrew Zimmer (LSU)| "Intrinsic and extrinsic geometries in several complex variables"]]<br />
|Gong<br />
|-<br />
|Dec 6<br />
|Charlotte Chan (MIT)<br />
|[[#Charlotte Chan (MIT)|"Flag varieties and representations of p-adic groups"]]<br />
|Erman<br />
|-<br />
|Dec 9 '''Monday 4-5 pm'''<br />
|Hui Yu (Columbia)<br />
|[[#Hui Yu (Columbia)|Singular sets in obstacle problems]]<br />
|Tran<br />
|-<br />
|Dec 11 '''Wednesday 2:30-3:30pm Room 911'''<br />
|Alex Waldron (Michigan)<br />
|[[#Alex Waldron (Michigan)|Gauge theory and geometric flows]]<br />
|Paul<br />
|-<br />
|Dec 11 '''Wednesday 4-5pm'''<br />
|Nick Higham (Manchester)<br />
|[[#Nick Higham (Manchester)|LAA lecture: Challenges in Multivalued Matrix Functions]]<br />
|Brualdi<br />
|-<br />
|Dec 13 <br />
|Chenxi Wu (Rutgers)<br />
|[[#Chenxi Wu (Rutgers)|Kazhdan's theorem on metric graphs]]<br />
|Ellenberg<br />
|-<br />
|Dec 18 '''Wednesday 4-5pm'''<br />
|Ruobing Zhang (Stony Brook)<br />
|[[#Ruobing Zhang (Stony Brook)|Geometry and analysis of degenerating Calabi-Yau manifolds]]<br />
|Paul<br />
|-<br />
|}<br />
<br />
==Spring 2020==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date <br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|<br />
|-<br />
|Jan 10<br />
|Thomas Lam (Michigan) <br />
|[[#Thomas Lam (Michigan) |Positive geometries and string theory amplitudes]]<br />
|Erman<br />
|-<br />
|Jan 21 '''Tuesday 4-5 pm in B139'''<br />
|[http://www.nd.edu/~cholak/ Peter Cholak] (Notre Dame) <br />
|[[#Peter Cholak (Notre Dame) |What can we compute from solutions to combinatorial problems?]]<br />
|Lempp<br />
|-<br />
|Jan 24<br />
|[https://math.duke.edu/people/saulo-orizaga Saulo Orizaga] (Duke)<br />
|[[#Saulo Orizaga (Duke) | Introduction to phase field models and their efficient numerical implementation ]]<br />
|<br />
|-<br />
|Jan 27 '''Monday 4-5 pm in 911'''<br />
|[https://math.yale.edu/people/caglar-uyanik Caglar Uyanik] (Yale)<br />
|[[#Caglar Uyanik (Yale) | Hausdorff dimension and gap distribution in billiards ]]<br />
|Ellenberg<br />
|-<br />
|Jan 29 '''Wednesday 4-5 pm'''<br />
|[https://ajzucker.wordpress.com/ Andy Zucker] (Lyon)<br />
|[[#Andy Zucker (Lyon) |Topological dynamics of countable groups and structures]]<br />
|Soskova/Lempp<br />
|-<br />
|Jan 31 <br />
|[https://services.math.duke.edu/~pierce/ Lillian Pierce] (Duke)<br />
|[[#Lillian Pierce (Duke) |On Bourgain’s counterexample for the Schrödinger maximal function]]<br />
|Marshall/Seeger<br />
|-<br />
|Feb 7<br />
|[https://web.math.princeton.edu/~jkileel/ Joe Kileel] (Princeton)<br />
|[[#Joe Kileel (Princeton) |Inverse Problems, Imaging and Tensor Decomposition]]<br />
|Roch<br />
|-<br />
|Feb 10<br />
|[https://clvinzan.math.ncsu.edu/ Cynthia Vinzant] (NCSU)<br />
|[[#Cynthia Vinzant (NCSU) |Matroids, log-concavity, and expanders]]<br />
|Roch/Erman<br />
|-<br />
|Feb 12 '''Wednesday 4-5 pm in VV 911'''<br />
|[https://www.machuang.org/ Jinzi Mac Huang] (UCSD)<br />
|[[#Jinzi Mac Huang (UCSD) |Mass transfer through fluid-structure interactions]]<br />
|Spagnolie<br />
|-<br />
|Feb 14<br />
|Reserved for job talk<br />
|<br />
|-<br />
|Feb 21<br />
|Shai Evra (IAS)<br />
|<br />
|Gurevich<br />
|<br />
|-<br />
|Feb 28<br />
|Brett Wick (Washington University, St. Louis)<br />
|<br />
|Seeger<br />
|-<br />
|March 6<br />
| Jessica Fintzen (Michigan)<br />
|<br />
|Marshall<br />
|-<br />
|March 13<br />
|<br />
|-<br />
|March 20<br />
|Spring break<br />
|<br />
|-<br />
|March 27<br />
|(Moduli Spaces Conference)<br />
|<br />
|Boggess, Sankar<br />
|-<br />
|April 3<br />
|Caroline Turnage-Butterbaugh (Carleton College)<br />
|<br />
|Marshall<br />
|-<br />
|April 10<br />
| Sarah Koch (Michigan)<br />
|<br />
| Bruce (WIMAW)<br />
|-<br />
|April 17<br />
|<br />
|<br />
|<br />
|-<br />
|April 23<br />
|Martin Hairer (Imperial College London)<br />
|Wolfgang Wasow Lecture<br />
|Hao Shen<br />
|-<br />
|April 24<br />
|Natasa Sesum (Rutgers University)<br />
|<br />
|Angenent<br />
|-<br />
|May 1<br />
|Robert Lazarsfeld (Stony Brook)<br />
|Distinguished lecture<br />
|Erman<br />
|}<br />
<br />
== Abstracts ==<br />
<br />
<br />
===Will Sawin (Columbia)===<br />
<br />
Title: On Chowla's Conjecture over F_q[T]<br />
<br />
Abstract: The Mobius function in number theory is a sequences of 1s, <br />
-1s, and 0s, which is simple to define and closely related to the <br />
prime numbers. Its behavior seems highly random. Chowla's conjecture <br />
is one precise formalization of this randomness, and has seen recent <br />
work by Matomaki, Radziwill, Tao, and Teravainen making progress on <br />
it. In joint work with Mark Shusterman, we modify this conjecture by <br />
replacing the natural numbers parameterizing this sequence with <br />
polynomials over a finite field. Under mild conditions on the finite <br />
field, we are able to prove a strong form of this conjecture. The <br />
proof is based on taking a geometric perspective on the problem, and <br />
succeeds because we are able to simplify the geometry using a trick <br />
based on the strange properties of polynomial derivatives over finite <br />
fields.<br />
<br />
<br />
===Yan Soibelman (Kansas State)===<br />
<br />
Title: Riemann-Hilbert correspondence and Fukaya categories<br />
<br />
Abstract: In this talk I am going to discuss the role of Fukaya categories in the Riemann-Hilbert correspondence<br />
for differential, q-difference and elliptic difference equations in dimension one.<br />
This approach not only gives a unified answer for several versions of the Riemann-Hilbert correspondence but also leads to a natural formulation<br />
of the non-abelian Hodge theory in dimension one. It also explains why periodic monopoles<br />
should appear as harmonic objects in this generalized non-abelian Hodge theory.<br />
All that is a part of the bigger project ``Holomorphic Floer theory",<br />
joint with Maxim Kontsevich.<br />
<br />
<br />
===Alicia Dickenstein (Buenos Aires)===<br />
<br />
Title: Algebra and geometry in the study of enzymatic cascades<br />
<br />
Abstract: In recent years, techniques from computational and real algebraic geometry have been successfully used to address mathematical challenges in systems biology. The algebraic theory of chemical reaction systems aims to understand their dynamic behavior by taking advantage of the inherent algebraic structure in the kinetic equations, and does not need the determination of the parameters a priori, which can be theoretically or practically impossible.<br />
I will give a gentle introduction to general results based on the network structure. In particular, I will describe a general framework for biological systems, called MESSI systems, that describe Modifications of type Enzyme-Substrate or Swap with Intermediates, and include many networks that model post-translational modifications of proteins inside the cell. I will also outline recent methods to address the important question of multistationarity, in particular in the study of enzymatic cascades, and will point out some of the mathematical challenges that arise from this application.<br />
<br />
<br />
=== Jianfeng Lu (Duke) ===<br />
Title: How to ``localize" the computation?<br />
<br />
It is often desirable to restrict the numerical computation to a local region to achieve best balance between accuracy and affordability in scientific computing. It is important to avoid artifacts and guarantee predictable modelling while artificial boundary conditions have to be introduced to restrict the computation. In this talk, we will discuss some recent understanding on how to achieve such local computation in the context of topological edge states and elliptic random media.<br />
<br />
<br />
===Eugenia Cheng (School of the Art Institute of Chicago)===<br />
<br />
Title: Character vs gender in mathematics and beyond<br />
<br />
Abstract: This presentation will be based on my experience of being a female mathematician, and teaching mathematics at all levels from elementary school to grad school. The question of why women are under-represented in mathematics is complex and there are no simple answers, only many many contributing factors. I will focus on character traits, and argue that if we focus on this rather than gender we can have a more productive and less divisive conversation. To try and focus on characters rather than genders I will introduce gender-neutral character adjectives "ingressive" and "congressive" to replace masculine and feminine. I will share my experience of teaching congressive abstract mathematics to art students, in a congressive way, and the possible effects this could have for everyone in mathematics, not just women.<br />
<br />
<br />
===Omer Mermelstein (Madison)===<br />
<br />
Title: Generic flat pregeometries<br />
<br />
Abstract: In model theory, the tamest of structures are the strongly minimal ones -- those in which every equation in a single variable has either finitely many or cofinitely many solution. Algebraically closed fields and vector spaces are the canonical examples. Zilber’s conjecture, later refuted by Hrushovski, states that the source of geometric complexity in a strongly minimal structure must be algebraic. The property of "flatness" (strict gammoid) of a geometry (matroid) is that which guarantees Hrushovski's construction is devoid of any associative structure.<br />
The majority of the talk will explain what flatness is, how it should be thought of, and how closely it relates to hypergraphs and Hrushovski's construction method. Model theory makes an appearance only in the second part, where I will share results pertaining to the specific family of geometries arising from Hrushovski's methods.<br />
<br />
<br />
===Shamgar Gurevich (Madison)===<br />
<br />
Title: Harmonic Analysis on GL(n) over Finite Fields.<br />
<br />
Abstract: There are many formulas that express interesting properties of a finite group G in terms of sums over its characters. For evaluating or estimating these sums, one of the most salient quantities to understand is the character ratio:<br />
<br />
trace(ρ(g)) / dim(ρ),<br />
<br />
for an irreducible representation ρ of G and an element g of G. For example, Diaconis and Shahshahani stated a formula of the mentioned type for analyzing certain random walks on G.<br />
<br />
Recently, we discovered that for classical groups G over finite fields there is a natural invariant of representations that provides strong information on the character ratio. We call this invariant rank. <br />
<br />
This talk will discuss the notion of rank for the group GLn over finite fields, demonstrate how it controls the character ratio, and explain how one can apply the results to verify mixing time and rate for certain random walks.<br />
<br />
This is joint work with Roger Howe (Yale and Texas AM). The numerics for this work was carried by Steve Goldstein (Madison)<br />
<br />
<br />
===Jose Rodriguez (UW-Madison)===<br />
<br />
Abstract: Determining the closest point to a model (subset of Euclidean space) is an important problem in many applications in science,<br />
engineering, and statistics. One way to solve this problem is by minimizing the squared Euclidean distance function using a gradient<br />
descent approach. However, when there are multiple local minima, there is no guarantee of convergence to the true global minimizer.<br />
An alternative method is to determine the critical points of an objective function on the model.<br />
In algebraic statistics, the models of interest are algebraic sets, i.e., solution sets to a system of multivariate polynomial equations. In this situation, the number of critical points of the squared Euclidean distance function on the model’s Zariski closure is a topological invariant called the Euclidean distance degree (ED degree).<br />
In this talk, I will present some models from computer vision and statistics that may be described as algebraic sets. Moreover,<br />
I will describe a topological method for determining a Euclidean distance degree and a numerical algebraic geometry approach for<br />
determining critical points of the squared Euclidean distance function.<br />
<br />
<br />
===Ananth Shankar (MIT)===<br />
<br />
Abstract: An abelian surface 'splits' if it admits a non-trivial map to some elliptic curve. It is well known that the set of abelian surfaces that split are sparse in the set of all abelian surfaces. Nevertheless, we prove that there are infinitely many split abelian surfaces in arithmetic one-parameter families of generically non-split abelian surfaces. I will describe this work, and if time permits, mention generalizations of this result to the setting of K3 surfaces, as well as applications to the dynamics of hecke orbits. This is joint work with Tang, Maulik-Tang, and Shankar-Tang-Tayou.<br />
<br />
<br />
===Franca Hoffman (Caltech)===<br />
<br />
Title: Gradient Flows: From PDE to Data Analysis.<br />
<br />
Abstract: Certain diffusive PDEs can be viewed as infinite-dimensional gradient flows. This fact has led to the development of new tools in various areas of mathematics ranging from PDE theory to data science. In this talk, we focus on two different directions: model-driven approaches and data-driven approaches.<br />
In the first part of the talk we use gradient flows for analyzing non-linear and non-local aggregation-diffusion equations when the corresponding energy functionals are not necessarily convex. Moreover, the gradient flow structure enables us to make connections to well-known functional inequalities, revealing possible links between the optimizers of these inequalities and the equilibria of certain aggregation-diffusion PDEs.<br />
In the second part, we use and develop gradient flow theory to design novel tools for data analysis. We draw a connection between gradient flows and Ensemble Kalman methods for parameter estimation. We introduce the Ensemble Kalman Sampler - a derivative-free methodology for model calibration and uncertainty quantification in expensive black-box models. The interacting particle dynamics underlying our algorithm can be approximated by a novel gradient flow structure in a modified Wasserstein metric which reflects particle correlations. The geometry of this modified Wasserstein metric is of independent theoretical interest.<br />
<br />
<br />
=== Jeffrey Danciger (UT Austin) ===<br />
<br />
Title: Affine geometry and the Auslander Conjecture<br />
<br />
Abstract: The Auslander Conjecture is an analogue of Bieberbach’s theory of Euclidean crystallographic groups in the setting of affine geometry. It predicts that a complete affine manifold (a manifold equipped with a complete torsion-free flat affine connection) which is compact must have virtually solvable fundamental group. The conjecture is known up to dimension six, but is known to fail if the compactness assumption is removed, even in low dimensions. We discuss some history of this conjecture, give some basic examples, and then survey some recent advances in the study of non-compact complete affine manifolds with non-solvable fundamental group. <br />
Tools from the deformation theory of pseudo-Riemannian hyperbolic manifolds and also from higher Teichm&uuml;ller theory will enter the picture.<br />
<br />
<br />
=== Tatyana Shcherbina (Princeton) ===<br />
<br />
Title: Random matrix theory and supersymmetry techniques<br />
<br />
Abstract: Starting from the works of Erdos, Yau, Schlein with coauthors, the significant progress in understanding the universal behavior of many random graph and random matrix models were achieved. However for the random matrices with a special structure our understanding is still very limited. In this talk I am going to overview applications of another approach to the study of the local eigenvalues statistics in random matrix theory based on so-called supersymmetry techniques (SUSY). SUSY approach is based on the representation of the determinant as an integral over the Grassmann (anticommuting) variables. Combining this representation with the representation of an inverse determinant as an integral over the Gaussian complex field, SUSY allows to obtain an integral representation for the main spectral characteristics of random matrices such as limiting density, correlation functions, the resolvent's elements, etc. This method is widely (and successfully) used in the physics literature and is potentially very powerful but the rigorous control of the integral representations, which can be obtained by this method, is quite difficult, and it requires powerful analytic and statistical mechanics tools. In this talk we will discuss some recent progress in application of SUSY to the analysis of local spectral characteristics of the prominent ensemble of random band matrices, i.e. random matrices<br />
whose entries become negligible if their distance from the main diagonal exceeds a certain parameter called the band width. <br />
<br />
<br />
=== Tingran Gao (University of Chicago) ===<br />
<br />
Title: Manifold Learning on Fibre Bundles<br />
<br />
Abstract: Spectral geometry has played an important role in modern geometric data analysis, where the technique is widely known as Laplacian eigenmaps or diffusion maps. In this talk, we present a geometric framework that studies graph representations of complex datasets, where each edge of the graph is equipped with a non-scalar transformation or correspondence. This new framework models such a dataset as a fibre bundle with a connection, and interprets the collection of pairwise functional relations as defining a horizontal diffusion process on the bundle driven by its projection on the base. The eigenstates of this horizontal diffusion process encode the “consistency” among objects in the dataset, and provide a lens through which the geometry of the dataset can be revealed. We demonstrate an application of this geometric framework on evolutionary anthropology.<br />
<br />
<br />
=== Andrew Zimmer (LSU) ===<br />
<br />
Title: Intrinsic and extrinsic geometries in several complex variables<br />
<br />
Abstract: A bounded domain in complex Euclidean space, despite being one of the simplest types of manifolds, has a number of interesting geometric structures. When the domain is pseudoconvex, it has a natural intrinsic geometry: the complete Kaehler-Einstein metric constructed by Cheng-Yau and Mok-Yau. When the domain is smoothly bounded, there is also a natural extrinsic structure: the CR-geometry of the boundary. In this talk, I will describe connections between these intrinsic and extrinsic geometries. Then, I will discuss how these connections can lead to new analytic results.<br />
<br />
=== Charlotte Chan (MIT) ===<br />
<br />
Title: Flag varieties and representations of p-adic groups<br />
<br />
Abstract: In the 1950s, Borel, Weil, and Bott showed that the<br />
irreducible representations of a complex reductive group can be<br />
realized in the cohomology of line bundles on flag varieties. In the<br />
1970s, Deligne and Lusztig constructed a family of subvarieties of<br />
flag varieties whose cohomology realizes the irreducible<br />
representations of reductive groups over finite fields. I will survey<br />
these stories, explain recent progress towards finding geometric<br />
constructions of representations of p-adic groups, and discuss<br />
interactions with the Langlands program.<br />
<br />
=== Hui Yu (Columbia) ===<br />
<br />
Title: Singular sets in obstacle problems<br />
<br />
Abstract: One of the most important free boundary problems is the obstacle problem. The regularity of its free boundary has been studied for over half a century. In this talk, we review some classical results as well as exciting new developments. In particular, we discuss the recent resolution of the regularity of the singular set for the fully nonlinear obstacle problem. This talk is based on a joint work with Ovidiu Savin at Columbia University.<br />
<br />
=== Alex Waldron (Michigan) ===<br />
<br />
Title: Gauge theory and geometric flows<br />
<br />
Abstract: I will give a brief introduction to two major areas of research in differential geometry: gauge theory and geometric flows. I'll then introduce a geometric flow (Yang-Mills flow) arising from a variational problem with origins in physics, which has been studied by geometric analysts since the early 1980s. I'll conclude by discussing my own work on the behavior of Yang-Mills flow in the critical dimension (n = 4).<br />
<br />
=== Nick Higham (Manchester) ===<br />
<br />
Title: Challenges in Multivalued Matrix Functions<br />
<br />
Abstract: In this lecture I will discuss multivalued matrix functions that arise in solving various kinds of matrix equations. The matrix logarithm is the prototypical example, and my first interaction with Hans Schneider was about this function. Another example is the Lambert W function of a matrix, which is much less well known but has been attracting recent interest. A theme of the talk is the importance of choosing appropriate principal values and making sure that the correct choices of signs and branches are used,<br />
both in theory and in computation. I will give examples where incorrect results have previously been obtained.<br />
<br />
I focus on matrix inverse trigonometric and inverse hyperbolic functions, beginning by investigating existence and characterization. Turning to the principal values, various functional identities are derived, some of which are new even in the scalar case, including a “round trip” formula that relates acos(cos A) to A and similar formulas for the other inverse functions. Key tools used in the derivations are the matrix unwinding function and the matrix sign function.<br />
<br />
A new inverse scaling and squaring type algorithm employing a Schur decomposition and variable-degree Pade approximation is derived for computing acos, and it is shown how it can also be used to compute asin, acosh, and asinh.<br />
<br />
=== Chenxi Wu (Rutgers) ===<br />
<br />
Title: Kazhdan's theorem on metric graphs<br />
<br />
Abstract: I will give an introduction to the concept of canonical (arakelov) metric on a metric graph, which is related to combinatorial questions like the counting of spanning trees, and generalizes the corresponding concept on Riemann surfaces. I will also present a recent result in collaboration with Farbod Shokrieh on the convergence of canonical metric under normal covers.<br />
<br />
=== Ruobing Zhang (Stony Brook) ===<br />
<br />
Title: Geometry and analysis of degenerating Calabi-Yau manifolds<br />
<br />
Abstract: This talk concerns a naturally occurring family of degenerating Calabi-Yau manifolds. A primary tool in analyzing their behavior is to combine the recently developed structure theory for Einstein manifolds and multi-scale singularity analysis for degenerating nonlinear PDEs in the collapsed setting. Based on the algebraic degeneration, we will give precise and more quantitative descriptions of singularity formation from both metric and analytic points of view.<br />
<br />
=== Thomas Lam (Michigan) === <br />
<br />
Title: Positive geometries and string theory amplitudes<br />
<br />
Abstract: Inspired by developments in quantum field theory, we<br />
recently defined the notion of a positive geometry, a class of spaces<br />
that includes convex polytopes, positive parts of projective toric<br />
varieties, and positive parts of flag varieties. I will discuss some<br />
basic features of the theory and an application to genus zero string<br />
theory amplitudes. As a special case, we obtain the Euler beta<br />
function, familiar to mathematicians, as the "stringy canonical form"<br />
of the closed interval.<br />
<br />
This talk is based on joint work with Arkani-Hamed, Bai, and He.<br />
<br />
=== Peter Cholak (Notre Dame) ===<br />
<br />
Title: What can we compute from solutions to combinatorial problems?<br />
<br />
Abstract: This will be an introductory talk to an exciting current <br />
research area in mathematical logic. Mostly we are interested in <br />
solutions to Ramsey's Theorem. Ramsey's Theorem says for colorings <br />
C of pairs of natural numbers, there is an infinite set H such that <br />
all pairs from H have the same constant color. H is called a homogeneous <br />
set for C. What can we compute from H? If you are not sure, come to <br />
the talk and find out!<br />
<br />
=== Saulo Orizaga (Duke) ===<br />
<br />
Title: Introduction to phase field models and their efficient numerical implementation<br />
<br />
Abstract: In this talk we will provide an introduction to phase field models. We will focus in models<br />
related to the Cahn-Hilliard (CH) type of partial differential equation (PDE). We will discuss the<br />
challenges associated in solving such higher order parabolic problems. We will present several<br />
new numerical methods that are fast and efficient for solving CH or CH-extended type of problems.<br />
The new methods and their energy-stability properties will be discussed and tested with several computational examples commonly found in material science problems. If time allows, we will talk about more applications in which phase field models are useful and applicable.<br />
<br />
=== Caglar Uyanik (Yale) ===<br />
<br />
Title: Hausdorff dimension and gap distribution in billiards<br />
<br />
Abstract: A classical “unfolding” procedure allows one to turn questions about billiard trajectories in a Euclidean polygon into questions about the geodesic flow on a surface equipped with a certain geometric structure. Surprisingly, the flow on the surface is in turn related to the geodesic flow on the classical moduli spaces of Riemann surfaces. Building on recent breakthrough results of Eskin-Mirzakhani-Mohammadi, we prove a large deviations result for Birkhoff averages as well as generalize a classical theorem of Masur on geodesics in the moduli spaces of translation surfaces. <br />
<br />
=== Andy Zucker (Lyon) ===<br />
<br />
Title: Topological dynamics of countable groups and structures<br />
<br />
Abstract: We give an introduction to the abstract topological dynamics <br />
of topological groups, i.e. the study of the continuous actions of a <br />
topological group on a compact space. We are particularly interested <br />
in the minimal actions, those for which every orbit is dense. <br />
The study of minimal actions is aided by a classical theorem of Ellis, <br />
who proved that for any topological group G, there exists a universal <br />
minimal flow (UMF), a minimal G-action which factors onto every other <br />
minimal G-action. Here, we will focus on two classes of groups: <br />
a countable discrete group and the automorphism group of a countable <br />
first-order structure. In the case of a countable discrete group, <br />
Baire category methods can be used to show that the collection of <br />
minimal flows is quite rich and that the UMF is rather complicated. <br />
For an automorphism group G of a countable structure, combinatorial <br />
methods can be used to show that sometimes, the UMF is trivial, or <br />
equivalently that every continuous action of G on a compact space <br />
admits a global fixed point.<br />
<br />
=== Lillian Pierce (Duke) ===<br />
<br />
Title: On Bourgain’s counterexample for the Schrödinger maximal function<br />
<br />
Abstract: In 1980, Carleson asked a question in harmonic analysis: to which Sobolev space $H^s$ must an initial data function belong, for a pointwise a.e. convergence result to hold for the solution to the associated linear Schrödinger equation? Over the next decades, many people developed counterexamples to push the (necessary) range of s up, and positive results to push the (sufficient) range of s down. Now, these ranges are finally meeting: Bourgain’s 2016 counterexample showed s < n/(2(n+1)) fails, and Du and Zhang’s 2019 paper shows that s>n/(2(n+1)) suffices. <br />
In this talk, we will give an overview of how to rigorously derive Bourgain’s 2016 counterexample, based on simple facts from number theory. We will show how to build Bourgain’s counterexample starting from “zero knowledge," and how to gradually optimize the set-up to arrive at the final counterexample. The talk will be broadly accessible, particularly if we live up to the claim of starting from “zero knowledge.”<br />
<br />
=== Joe Kileel (Princeton) ===<br />
<br />
Title: Inverse Problems, Imaging and Tensor Decomposition<br />
<br />
Abstract: Perspectives from computational algebra and optimization are brought <br />
to bear on a scientific application and a data science application. <br />
In the first part of the talk, I will discuss cryo-electron microscopy <br />
(cryo-EM), an imaging technique to determine the 3-D shape of <br />
macromolecules from many noisy 2-D projections, recognized by the 2017 <br />
Chemistry Nobel Prize. Mathematically, cryo-EM presents a <br />
particularly rich inverse problem, with unknown orientations, extreme <br />
noise, big data and conformational heterogeneity. In particular, this <br />
motivates a general framework for statistical estimation under compact <br />
group actions, connecting information theory and group invariant <br />
theory. In the second part of the talk, I will discuss tensor rank <br />
decomposition, a higher-order variant of PCA broadly applicable in <br />
data science. A fast algorithm is introduced and analyzed, combining <br />
ideas of Sylvester and the power method.<br />
<br />
=== Cynthia Vinzant (NCSU) ===<br />
<br />
Title: Matroids, log-concavity, and expanders<br />
<br />
Abstract: Matroids are combinatorial objects that model various types of independence. They appear several fields mathematics, including graph theory, combinatorial optimization, and algebraic geometry. In this talk, I will introduce the theory of matroids along with the closely related class of polynomials called strongly log-concave polynomials. Strong log-concavity is a functional property of a real multivariate polynomial that translates to useful conditions on its coefficients. Discrete probability distributions defined by these coefficients inherit several of these nice properties. I will discuss the beautiful real and combinatorial geometry underlying these polynomials and describe applications to random walks on the faces of simplicial complexes. Consequences include proofs of Mason's conjecture that the sequence of numbers of independent sets of a matroid is ultra log-concave and the Mihail-Vazirani conjecture that the basis exchange graph of a matroid has expansion at least one. This is based on joint work with Nima Anari, Kuikui Liu, and Shayan Oveis Gharan.<br />
<br />
== Future Colloquia ==<br />
[[Colloquia/Fall 2020| Fall 2020]]<br />
<br />
== Past Colloquia ==<br />
<br />
[[Colloquia/Blank|Blank]]<br />
<br />
[[Colloquia/Spring2019|Spring 2019]]<br />
<br />
[[Colloquia/Fall2018|Fall 2018]]<br />
<br />
[[Colloquia/Spring2018|Spring 2018]]<br />
<br />
[[Colloquia/Fall2017|Fall 2017]]<br />
<br />
[[Colloquia/Spring2017|Spring 2017]]<br />
<br />
[[Archived Fall 2016 Colloquia|Fall 2016]]<br />
<br />
[[Colloquia/Spring2016|Spring 2016]]<br />
<br />
[[Colloquia/Fall2015|Fall 2015]]<br />
<br />
[[Colloquia/Spring2014|Spring 2015]]<br />
<br />
[[Colloquia/Fall2014|Fall 2014]]<br />
<br />
[[Colloquia/Spring2014|Spring 2014]]<br />
<br />
[[Colloquia/Fall2013|Fall 2013]]<br />
<br />
[[Colloquia 2012-2013|Spring 2013]]<br />
<br />
[[Colloquia 2012-2013#Fall 2012|Fall 2012]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Colloquia/Spring2020&diff=18873Colloquia/Spring20202020-02-03T17:48:23Z<p>Spagnolie: /* Spring 2020 */</p>
<hr />
<div>= Mathematics Colloquium =<br />
<br />
All colloquia are on Fridays at 4:00 pm in Van Vleck B239, '''unless otherwise indicated'''.<br />
<br />
<br />
<br />
==Fall 2019==<br />
{| cellpadding="8"<br />
!align="left" | date <br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
|Sept 6 '''Room 911'''<br />
| Will Sawin (Columbia)<br />
| [[#Will Sawin (Columbia) | On Chowla's Conjecture over F_q[T] ]]<br />
| Marshall<br />
|-<br />
|Sept 13<br />
| [https://www.math.ksu.edu/~soibel/ Yan Soibelman] (Kansas State)<br />
|[[#Yan Soibelman (Kansas State)| Riemann-Hilbert correspondence and Fukaya categories ]]<br />
| Caldararu<br />
|<br />
|-<br />
|Sept 16 '''Monday Room 911'''<br />
| [http://mate.dm.uba.ar/~alidick/ Alicia Dickenstein] (Buenos Aires)<br />
|[[#Alicia Dickenstein (Buenos Aires)| Algebra and geometry in the study of enzymatic cascades ]]<br />
| Craciun<br />
|<br />
|-<br />
|Sept 20<br />
| [https://math.duke.edu/~jianfeng/ Jianfeng Lu] (Duke)<br />
|[[#Jianfeng Lu (Duke) | How to "localize" the computation?]]<br />
| Qin<br />
|<br />
|-<br />
|Sept 26 '''Thursday 3-4 pm Room 911'''<br />
| [http://eugeniacheng.com/ Eugenia Cheng] (School of the Art Institute of Chicago)<br />
| [[#Eugenia Cheng (School of the Art Institute of Chicago)| Character vs gender in mathematics and beyond ]]<br />
| Marshall / Friends of UW Madison Libraries<br />
|<br />
|-<br />
|Sept 27<br />
|<br />
|<br />
|-<br />
|Oct 4<br />
|<br />
|<br />
|-<br />
|Oct 11<br />
| Omer Mermelstein (Madison)<br />
| [[#Omer Mermelstein (Madison)| Generic flat pregeometries ]]<br />
|Andrews<br />
|<br />
|-<br />
|Oct 18<br />
| Shamgar Gurevich (Madison)<br />
| [[#Shamgar Gurevich (Madison) | Harmonic Analysis on GL(n) over Finite Fields ]]<br />
| Marshall<br />
|-<br />
|Oct 25<br />
|<br />
|-<br />
|Nov 1<br />
|Elchanan Mossel (MIT)<br />
|Distinguished Lecture<br />
|Roch<br />
|-<br />
|Nov 8<br />
|Jose Rodriguez (UW-Madison)<br />
|[[#Jose Rodriguez (UW-Madison) | Nearest Point Problems and Euclidean Distance Degrees]]<br />
|Erman<br />
|-<br />
|Nov 13 '''Wednesday 4-5pm'''<br />
|Ananth Shankar (MIT)<br />
|Exceptional splitting of abelian surfaces<br />
|-<br />
|Nov 20 '''Wednesday 4-5pm'''<br />
|Franca Hoffman (Caltech)<br />
|[[#Franca Hoffman (Caltech) | Gradient Flows: From PDE to Data Analysis]]<br />
|Smith<br />
|-<br />
|Nov 22<br />
| Jeffrey Danciger (UT Austin)<br />
| [[#Jeffrey Danciger (UT Austin) | "Affine geometry and the Auslander Conjecture"]]<br />
| Kent<br />
|-<br />
|Nov 25 '''Monday 4-5 pm Room 911'''<br />
|Tatyana Shcherbina (Princeton)<br />
| [[# Tatyana Shcherbina (Princeton)| "Random matrix theory and supersymmetry techniques"]]<br />
|Roch<br />
|-<br />
|Nov 29<br />
|Thanksgiving<br />
|<br />
|-<br />
|Dec 2 '''Monday 4-5pm'''<br />
|Tingran Gao (University of Chicago)<br />
| [[#Tingran Gao (University of Chicago)| "Manifold Learning on Fibre Bundles"]]<br />
|Smith<br />
|-<br />
|Dec 4 '''Wednesday 4-5 pm Room 911'''<br />
|Andrew Zimmer (LSU)<br />
|[[#Andrew Zimmer (LSU)| "Intrinsic and extrinsic geometries in several complex variables"]]<br />
|Gong<br />
|-<br />
|Dec 6<br />
|Charlotte Chan (MIT)<br />
|[[#Charlotte Chan (MIT)|"Flag varieties and representations of p-adic groups"]]<br />
|Erman<br />
|-<br />
|Dec 9 '''Monday 4-5 pm'''<br />
|Hui Yu (Columbia)<br />
|[[#Hui Yu (Columbia)|Singular sets in obstacle problems]]<br />
|Tran<br />
|-<br />
|Dec 11 '''Wednesday 2:30-3:30pm Room 911'''<br />
|Alex Waldron (Michigan)<br />
|[[#Alex Waldron (Michigan)|Gauge theory and geometric flows]]<br />
|Paul<br />
|-<br />
|Dec 11 '''Wednesday 4-5pm'''<br />
|Nick Higham (Manchester)<br />
|[[#Nick Higham (Manchester)|LAA lecture: Challenges in Multivalued Matrix Functions]]<br />
|Brualdi<br />
|-<br />
|Dec 13 <br />
|Chenxi Wu (Rutgers)<br />
|[[#Chenxi Wu (Rutgers)|Kazhdan's theorem on metric graphs]]<br />
|Ellenberg<br />
|-<br />
|Dec 18 '''Wednesday 4-5pm'''<br />
|Ruobing Zhang (Stony Brook)<br />
|[[#Ruobing Zhang (Stony Brook)|Geometry and analysis of degenerating Calabi-Yau manifolds]]<br />
|Paul<br />
|-<br />
|}<br />
<br />
==Spring 2020==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date <br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|<br />
|-<br />
|Jan 10<br />
|Thomas Lam (Michigan) <br />
|[[#Thomas Lam (Michigan) |Positive geometries and string theory amplitudes]]<br />
|Erman<br />
|-<br />
|Jan 21 '''Tuesday 4-5 pm in B139'''<br />
|[http://www.nd.edu/~cholak/ Peter Cholak] (Notre Dame) <br />
|[[#Peter Cholak (Notre Dame) |What can we compute from solutions to combinatorial problems?]]<br />
|Lempp<br />
|-<br />
|Jan 24<br />
|[https://math.duke.edu/people/saulo-orizaga Saulo Orizaga] (Duke)<br />
|[[#Saulo Orizaga (Duke) | Introduction to phase field models and their efficient numerical implementation ]]<br />
|<br />
|-<br />
|Jan 27 '''Monday 4-5 pm in 911'''<br />
|[https://math.yale.edu/people/caglar-uyanik Caglar Uyanik] (Yale)<br />
|[[#Caglar Uyanik (Yale) | Hausdorff dimension and gap distribution in billiards ]]<br />
|Ellenberg<br />
|-<br />
|Jan 29 '''Wednesday 4-5 pm'''<br />
|[https://ajzucker.wordpress.com/ Andy Zucker] (Lyon)<br />
|[[#Andy Zucker (Lyon) |Topological dynamics of countable groups and structures]]<br />
|Soskova/Lempp<br />
|-<br />
|Jan 31 <br />
|[https://services.math.duke.edu/~pierce/ Lillian Pierce] (Duke)<br />
|[[#Lillian Pierce (Duke) |On Bourgain’s counterexample for the Schrödinger maximal function]]<br />
|Marshall/Seeger<br />
|-<br />
|Feb 7<br />
|[https://web.math.princeton.edu/~jkileel/ Joe Kileel] (Princeton)<br />
|[[#Joe Kileel (Princeton) |Inverse Problems, Imaging and Tensor Decomposition]]<br />
|Roch<br />
|-<br />
|Feb 10<br />
|[https://clvinzan.math.ncsu.edu/ Cynthia Vinzant] (NCSU)<br />
|[[#Cynthia Vinzant (NCSU) |Matroids, log-concavity, and expanders]]<br />
|Roch/Erman<br />
|-<br />
|Feb 12 '''Wednesday 4-5 pm in VV 911'''<br />
|[https://www.machuang.org/ Jinzi Mac Huang] (UCSD)<br />
|[[#Jinzi Mac Huang (UCSD) |Math in the lab: mass transfer through fluid-structure interactions]]<br />
|Spagnolie<br />
|-<br />
|Feb 14<br />
|Reserved for job talk<br />
|<br />
|-<br />
|Feb 21<br />
|Shai Evra (IAS)<br />
|<br />
|Gurevich<br />
|<br />
|-<br />
|Feb 28<br />
|Brett Wick (Washington University, St. Louis)<br />
|<br />
|Seeger<br />
|-<br />
|March 6<br />
| Jessica Fintzen (Michigan)<br />
|<br />
|Marshall<br />
|-<br />
|March 13<br />
|<br />
|-<br />
|March 20<br />
|Spring break<br />
|<br />
|-<br />
|March 27<br />
|(Moduli Spaces Conference)<br />
|<br />
|Boggess, Sankar<br />
|-<br />
|April 3<br />
|Caroline Turnage-Butterbaugh (Carleton College)<br />
|<br />
|Marshall<br />
|-<br />
|April 10<br />
| Sarah Koch (Michigan)<br />
|<br />
| Bruce (WIMAW)<br />
|-<br />
|April 17<br />
|<br />
|<br />
|<br />
|-<br />
|April 23<br />
|Martin Hairer (Imperial College London)<br />
|Wolfgang Wasow Lecture<br />
|Hao Shen<br />
|-<br />
|April 24<br />
|Natasa Sesum (Rutgers University)<br />
|<br />
|Angenent<br />
|-<br />
|May 1<br />
|Robert Lazarsfeld (Stony Brook)<br />
|Distinguished lecture<br />
|Erman<br />
|}<br />
<br />
== Abstracts ==<br />
<br />
<br />
===Will Sawin (Columbia)===<br />
<br />
Title: On Chowla's Conjecture over F_q[T]<br />
<br />
Abstract: The Mobius function in number theory is a sequences of 1s, <br />
-1s, and 0s, which is simple to define and closely related to the <br />
prime numbers. Its behavior seems highly random. Chowla's conjecture <br />
is one precise formalization of this randomness, and has seen recent <br />
work by Matomaki, Radziwill, Tao, and Teravainen making progress on <br />
it. In joint work with Mark Shusterman, we modify this conjecture by <br />
replacing the natural numbers parameterizing this sequence with <br />
polynomials over a finite field. Under mild conditions on the finite <br />
field, we are able to prove a strong form of this conjecture. The <br />
proof is based on taking a geometric perspective on the problem, and <br />
succeeds because we are able to simplify the geometry using a trick <br />
based on the strange properties of polynomial derivatives over finite <br />
fields.<br />
<br />
<br />
===Yan Soibelman (Kansas State)===<br />
<br />
Title: Riemann-Hilbert correspondence and Fukaya categories<br />
<br />
Abstract: In this talk I am going to discuss the role of Fukaya categories in the Riemann-Hilbert correspondence<br />
for differential, q-difference and elliptic difference equations in dimension one.<br />
This approach not only gives a unified answer for several versions of the Riemann-Hilbert correspondence but also leads to a natural formulation<br />
of the non-abelian Hodge theory in dimension one. It also explains why periodic monopoles<br />
should appear as harmonic objects in this generalized non-abelian Hodge theory.<br />
All that is a part of the bigger project ``Holomorphic Floer theory",<br />
joint with Maxim Kontsevich.<br />
<br />
<br />
===Alicia Dickenstein (Buenos Aires)===<br />
<br />
Title: Algebra and geometry in the study of enzymatic cascades<br />
<br />
Abstract: In recent years, techniques from computational and real algebraic geometry have been successfully used to address mathematical challenges in systems biology. The algebraic theory of chemical reaction systems aims to understand their dynamic behavior by taking advantage of the inherent algebraic structure in the kinetic equations, and does not need the determination of the parameters a priori, which can be theoretically or practically impossible.<br />
I will give a gentle introduction to general results based on the network structure. In particular, I will describe a general framework for biological systems, called MESSI systems, that describe Modifications of type Enzyme-Substrate or Swap with Intermediates, and include many networks that model post-translational modifications of proteins inside the cell. I will also outline recent methods to address the important question of multistationarity, in particular in the study of enzymatic cascades, and will point out some of the mathematical challenges that arise from this application.<br />
<br />
<br />
=== Jianfeng Lu (Duke) ===<br />
Title: How to ``localize" the computation?<br />
<br />
It is often desirable to restrict the numerical computation to a local region to achieve best balance between accuracy and affordability in scientific computing. It is important to avoid artifacts and guarantee predictable modelling while artificial boundary conditions have to be introduced to restrict the computation. In this talk, we will discuss some recent understanding on how to achieve such local computation in the context of topological edge states and elliptic random media.<br />
<br />
<br />
===Eugenia Cheng (School of the Art Institute of Chicago)===<br />
<br />
Title: Character vs gender in mathematics and beyond<br />
<br />
Abstract: This presentation will be based on my experience of being a female mathematician, and teaching mathematics at all levels from elementary school to grad school. The question of why women are under-represented in mathematics is complex and there are no simple answers, only many many contributing factors. I will focus on character traits, and argue that if we focus on this rather than gender we can have a more productive and less divisive conversation. To try and focus on characters rather than genders I will introduce gender-neutral character adjectives "ingressive" and "congressive" to replace masculine and feminine. I will share my experience of teaching congressive abstract mathematics to art students, in a congressive way, and the possible effects this could have for everyone in mathematics, not just women.<br />
<br />
<br />
===Omer Mermelstein (Madison)===<br />
<br />
Title: Generic flat pregeometries<br />
<br />
Abstract: In model theory, the tamest of structures are the strongly minimal ones -- those in which every equation in a single variable has either finitely many or cofinitely many solution. Algebraically closed fields and vector spaces are the canonical examples. Zilber’s conjecture, later refuted by Hrushovski, states that the source of geometric complexity in a strongly minimal structure must be algebraic. The property of "flatness" (strict gammoid) of a geometry (matroid) is that which guarantees Hrushovski's construction is devoid of any associative structure.<br />
The majority of the talk will explain what flatness is, how it should be thought of, and how closely it relates to hypergraphs and Hrushovski's construction method. Model theory makes an appearance only in the second part, where I will share results pertaining to the specific family of geometries arising from Hrushovski's methods.<br />
<br />
<br />
===Shamgar Gurevich (Madison)===<br />
<br />
Title: Harmonic Analysis on GL(n) over Finite Fields.<br />
<br />
Abstract: There are many formulas that express interesting properties of a finite group G in terms of sums over its characters. For evaluating or estimating these sums, one of the most salient quantities to understand is the character ratio:<br />
<br />
trace(ρ(g)) / dim(ρ),<br />
<br />
for an irreducible representation ρ of G and an element g of G. For example, Diaconis and Shahshahani stated a formula of the mentioned type for analyzing certain random walks on G.<br />
<br />
Recently, we discovered that for classical groups G over finite fields there is a natural invariant of representations that provides strong information on the character ratio. We call this invariant rank. <br />
<br />
This talk will discuss the notion of rank for the group GLn over finite fields, demonstrate how it controls the character ratio, and explain how one can apply the results to verify mixing time and rate for certain random walks.<br />
<br />
This is joint work with Roger Howe (Yale and Texas AM). The numerics for this work was carried by Steve Goldstein (Madison)<br />
<br />
<br />
===Jose Rodriguez (UW-Madison)===<br />
<br />
Abstract: Determining the closest point to a model (subset of Euclidean space) is an important problem in many applications in science,<br />
engineering, and statistics. One way to solve this problem is by minimizing the squared Euclidean distance function using a gradient<br />
descent approach. However, when there are multiple local minima, there is no guarantee of convergence to the true global minimizer.<br />
An alternative method is to determine the critical points of an objective function on the model.<br />
In algebraic statistics, the models of interest are algebraic sets, i.e., solution sets to a system of multivariate polynomial equations. In this situation, the number of critical points of the squared Euclidean distance function on the model’s Zariski closure is a topological invariant called the Euclidean distance degree (ED degree).<br />
In this talk, I will present some models from computer vision and statistics that may be described as algebraic sets. Moreover,<br />
I will describe a topological method for determining a Euclidean distance degree and a numerical algebraic geometry approach for<br />
determining critical points of the squared Euclidean distance function.<br />
<br />
<br />
===Ananth Shankar (MIT)===<br />
<br />
Abstract: An abelian surface 'splits' if it admits a non-trivial map to some elliptic curve. It is well known that the set of abelian surfaces that split are sparse in the set of all abelian surfaces. Nevertheless, we prove that there are infinitely many split abelian surfaces in arithmetic one-parameter families of generically non-split abelian surfaces. I will describe this work, and if time permits, mention generalizations of this result to the setting of K3 surfaces, as well as applications to the dynamics of hecke orbits. This is joint work with Tang, Maulik-Tang, and Shankar-Tang-Tayou.<br />
<br />
<br />
===Franca Hoffman (Caltech)===<br />
<br />
Title: Gradient Flows: From PDE to Data Analysis.<br />
<br />
Abstract: Certain diffusive PDEs can be viewed as infinite-dimensional gradient flows. This fact has led to the development of new tools in various areas of mathematics ranging from PDE theory to data science. In this talk, we focus on two different directions: model-driven approaches and data-driven approaches.<br />
In the first part of the talk we use gradient flows for analyzing non-linear and non-local aggregation-diffusion equations when the corresponding energy functionals are not necessarily convex. Moreover, the gradient flow structure enables us to make connections to well-known functional inequalities, revealing possible links between the optimizers of these inequalities and the equilibria of certain aggregation-diffusion PDEs.<br />
In the second part, we use and develop gradient flow theory to design novel tools for data analysis. We draw a connection between gradient flows and Ensemble Kalman methods for parameter estimation. We introduce the Ensemble Kalman Sampler - a derivative-free methodology for model calibration and uncertainty quantification in expensive black-box models. The interacting particle dynamics underlying our algorithm can be approximated by a novel gradient flow structure in a modified Wasserstein metric which reflects particle correlations. The geometry of this modified Wasserstein metric is of independent theoretical interest.<br />
<br />
<br />
=== Jeffrey Danciger (UT Austin) ===<br />
<br />
Title: Affine geometry and the Auslander Conjecture<br />
<br />
Abstract: The Auslander Conjecture is an analogue of Bieberbach’s theory of Euclidean crystallographic groups in the setting of affine geometry. It predicts that a complete affine manifold (a manifold equipped with a complete torsion-free flat affine connection) which is compact must have virtually solvable fundamental group. The conjecture is known up to dimension six, but is known to fail if the compactness assumption is removed, even in low dimensions. We discuss some history of this conjecture, give some basic examples, and then survey some recent advances in the study of non-compact complete affine manifolds with non-solvable fundamental group. <br />
Tools from the deformation theory of pseudo-Riemannian hyperbolic manifolds and also from higher Teichm&uuml;ller theory will enter the picture.<br />
<br />
<br />
=== Tatyana Shcherbina (Princeton) ===<br />
<br />
Title: Random matrix theory and supersymmetry techniques<br />
<br />
Abstract: Starting from the works of Erdos, Yau, Schlein with coauthors, the significant progress in understanding the universal behavior of many random graph and random matrix models were achieved. However for the random matrices with a special structure our understanding is still very limited. In this talk I am going to overview applications of another approach to the study of the local eigenvalues statistics in random matrix theory based on so-called supersymmetry techniques (SUSY). SUSY approach is based on the representation of the determinant as an integral over the Grassmann (anticommuting) variables. Combining this representation with the representation of an inverse determinant as an integral over the Gaussian complex field, SUSY allows to obtain an integral representation for the main spectral characteristics of random matrices such as limiting density, correlation functions, the resolvent's elements, etc. This method is widely (and successfully) used in the physics literature and is potentially very powerful but the rigorous control of the integral representations, which can be obtained by this method, is quite difficult, and it requires powerful analytic and statistical mechanics tools. In this talk we will discuss some recent progress in application of SUSY to the analysis of local spectral characteristics of the prominent ensemble of random band matrices, i.e. random matrices<br />
whose entries become negligible if their distance from the main diagonal exceeds a certain parameter called the band width. <br />
<br />
<br />
=== Tingran Gao (University of Chicago) ===<br />
<br />
Title: Manifold Learning on Fibre Bundles<br />
<br />
Abstract: Spectral geometry has played an important role in modern geometric data analysis, where the technique is widely known as Laplacian eigenmaps or diffusion maps. In this talk, we present a geometric framework that studies graph representations of complex datasets, where each edge of the graph is equipped with a non-scalar transformation or correspondence. This new framework models such a dataset as a fibre bundle with a connection, and interprets the collection of pairwise functional relations as defining a horizontal diffusion process on the bundle driven by its projection on the base. The eigenstates of this horizontal diffusion process encode the “consistency” among objects in the dataset, and provide a lens through which the geometry of the dataset can be revealed. We demonstrate an application of this geometric framework on evolutionary anthropology.<br />
<br />
<br />
=== Andrew Zimmer (LSU) ===<br />
<br />
Title: Intrinsic and extrinsic geometries in several complex variables<br />
<br />
Abstract: A bounded domain in complex Euclidean space, despite being one of the simplest types of manifolds, has a number of interesting geometric structures. When the domain is pseudoconvex, it has a natural intrinsic geometry: the complete Kaehler-Einstein metric constructed by Cheng-Yau and Mok-Yau. When the domain is smoothly bounded, there is also a natural extrinsic structure: the CR-geometry of the boundary. In this talk, I will describe connections between these intrinsic and extrinsic geometries. Then, I will discuss how these connections can lead to new analytic results.<br />
<br />
=== Charlotte Chan (MIT) ===<br />
<br />
Title: Flag varieties and representations of p-adic groups<br />
<br />
Abstract: In the 1950s, Borel, Weil, and Bott showed that the<br />
irreducible representations of a complex reductive group can be<br />
realized in the cohomology of line bundles on flag varieties. In the<br />
1970s, Deligne and Lusztig constructed a family of subvarieties of<br />
flag varieties whose cohomology realizes the irreducible<br />
representations of reductive groups over finite fields. I will survey<br />
these stories, explain recent progress towards finding geometric<br />
constructions of representations of p-adic groups, and discuss<br />
interactions with the Langlands program.<br />
<br />
=== Hui Yu (Columbia) ===<br />
<br />
Title: Singular sets in obstacle problems<br />
<br />
Abstract: One of the most important free boundary problems is the obstacle problem. The regularity of its free boundary has been studied for over half a century. In this talk, we review some classical results as well as exciting new developments. In particular, we discuss the recent resolution of the regularity of the singular set for the fully nonlinear obstacle problem. This talk is based on a joint work with Ovidiu Savin at Columbia University.<br />
<br />
=== Alex Waldron (Michigan) ===<br />
<br />
Title: Gauge theory and geometric flows<br />
<br />
Abstract: I will give a brief introduction to two major areas of research in differential geometry: gauge theory and geometric flows. I'll then introduce a geometric flow (Yang-Mills flow) arising from a variational problem with origins in physics, which has been studied by geometric analysts since the early 1980s. I'll conclude by discussing my own work on the behavior of Yang-Mills flow in the critical dimension (n = 4).<br />
<br />
=== Nick Higham (Manchester) ===<br />
<br />
Title: Challenges in Multivalued Matrix Functions<br />
<br />
Abstract: In this lecture I will discuss multivalued matrix functions that arise in solving various kinds of matrix equations. The matrix logarithm is the prototypical example, and my first interaction with Hans Schneider was about this function. Another example is the Lambert W function of a matrix, which is much less well known but has been attracting recent interest. A theme of the talk is the importance of choosing appropriate principal values and making sure that the correct choices of signs and branches are used,<br />
both in theory and in computation. I will give examples where incorrect results have previously been obtained.<br />
<br />
I focus on matrix inverse trigonometric and inverse hyperbolic functions, beginning by investigating existence and characterization. Turning to the principal values, various functional identities are derived, some of which are new even in the scalar case, including a “round trip” formula that relates acos(cos A) to A and similar formulas for the other inverse functions. Key tools used in the derivations are the matrix unwinding function and the matrix sign function.<br />
<br />
A new inverse scaling and squaring type algorithm employing a Schur decomposition and variable-degree Pade approximation is derived for computing acos, and it is shown how it can also be used to compute asin, acosh, and asinh.<br />
<br />
=== Chenxi Wu (Rutgers) ===<br />
<br />
Title: Kazhdan's theorem on metric graphs<br />
<br />
Abstract: I will give an introduction to the concept of canonical (arakelov) metric on a metric graph, which is related to combinatorial questions like the counting of spanning trees, and generalizes the corresponding concept on Riemann surfaces. I will also present a recent result in collaboration with Farbod Shokrieh on the convergence of canonical metric under normal covers.<br />
<br />
=== Ruobing Zhang (Stony Brook) ===<br />
<br />
Title: Geometry and analysis of degenerating Calabi-Yau manifolds<br />
<br />
Abstract: This talk concerns a naturally occurring family of degenerating Calabi-Yau manifolds. A primary tool in analyzing their behavior is to combine the recently developed structure theory for Einstein manifolds and multi-scale singularity analysis for degenerating nonlinear PDEs in the collapsed setting. Based on the algebraic degeneration, we will give precise and more quantitative descriptions of singularity formation from both metric and analytic points of view.<br />
<br />
=== Thomas Lam (Michigan) === <br />
<br />
Title: Positive geometries and string theory amplitudes<br />
<br />
Abstract: Inspired by developments in quantum field theory, we<br />
recently defined the notion of a positive geometry, a class of spaces<br />
that includes convex polytopes, positive parts of projective toric<br />
varieties, and positive parts of flag varieties. I will discuss some<br />
basic features of the theory and an application to genus zero string<br />
theory amplitudes. As a special case, we obtain the Euler beta<br />
function, familiar to mathematicians, as the "stringy canonical form"<br />
of the closed interval.<br />
<br />
This talk is based on joint work with Arkani-Hamed, Bai, and He.<br />
<br />
=== Peter Cholak (Notre Dame) ===<br />
<br />
Title: What can we compute from solutions to combinatorial problems?<br />
<br />
Abstract: This will be an introductory talk to an exciting current <br />
research area in mathematical logic. Mostly we are interested in <br />
solutions to Ramsey's Theorem. Ramsey's Theorem says for colorings <br />
C of pairs of natural numbers, there is an infinite set H such that <br />
all pairs from H have the same constant color. H is called a homogeneous <br />
set for C. What can we compute from H? If you are not sure, come to <br />
the talk and find out!<br />
<br />
=== Saulo Orizaga (Duke) ===<br />
<br />
Title: Introduction to phase field models and their efficient numerical implementation<br />
<br />
Abstract: In this talk we will provide an introduction to phase field models. We will focus in models<br />
related to the Cahn-Hilliard (CH) type of partial differential equation (PDE). We will discuss the<br />
challenges associated in solving such higher order parabolic problems. We will present several<br />
new numerical methods that are fast and efficient for solving CH or CH-extended type of problems.<br />
The new methods and their energy-stability properties will be discussed and tested with several computational examples commonly found in material science problems. If time allows, we will talk about more applications in which phase field models are useful and applicable.<br />
<br />
=== Caglar Uyanik (Yale) ===<br />
<br />
Title: Hausdorff dimension and gap distribution in billiards<br />
<br />
Abstract: A classical “unfolding” procedure allows one to turn questions about billiard trajectories in a Euclidean polygon into questions about the geodesic flow on a surface equipped with a certain geometric structure. Surprisingly, the flow on the surface is in turn related to the geodesic flow on the classical moduli spaces of Riemann surfaces. Building on recent breakthrough results of Eskin-Mirzakhani-Mohammadi, we prove a large deviations result for Birkhoff averages as well as generalize a classical theorem of Masur on geodesics in the moduli spaces of translation surfaces. <br />
<br />
=== Andy Zucker (Lyon) ===<br />
<br />
Title: Topological dynamics of countable groups and structures<br />
<br />
Abstract: We give an introduction to the abstract topological dynamics <br />
of topological groups, i.e. the study of the continuous actions of a <br />
topological group on a compact space. We are particularly interested <br />
in the minimal actions, those for which every orbit is dense. <br />
The study of minimal actions is aided by a classical theorem of Ellis, <br />
who proved that for any topological group G, there exists a universal <br />
minimal flow (UMF), a minimal G-action which factors onto every other <br />
minimal G-action. Here, we will focus on two classes of groups: <br />
a countable discrete group and the automorphism group of a countable <br />
first-order structure. In the case of a countable discrete group, <br />
Baire category methods can be used to show that the collection of <br />
minimal flows is quite rich and that the UMF is rather complicated. <br />
For an automorphism group G of a countable structure, combinatorial <br />
methods can be used to show that sometimes, the UMF is trivial, or <br />
equivalently that every continuous action of G on a compact space <br />
admits a global fixed point.<br />
<br />
=== Lillian Pierce (Duke) ===<br />
<br />
Title: On Bourgain’s counterexample for the Schrödinger maximal function<br />
<br />
Abstract: In 1980, Carleson asked a question in harmonic analysis: to which Sobolev space $H^s$ must an initial data function belong, for a pointwise a.e. convergence result to hold for the solution to the associated linear Schrödinger equation? Over the next decades, many people developed counterexamples to push the (necessary) range of s up, and positive results to push the (sufficient) range of s down. Now, these ranges are finally meeting: Bourgain’s 2016 counterexample showed s < n/(2(n+1)) fails, and Du and Zhang’s 2019 paper shows that s>n/(2(n+1)) suffices. <br />
In this talk, we will give an overview of how to rigorously derive Bourgain’s 2016 counterexample, based on simple facts from number theory. We will show how to build Bourgain’s counterexample starting from “zero knowledge," and how to gradually optimize the set-up to arrive at the final counterexample. The talk will be broadly accessible, particularly if we live up to the claim of starting from “zero knowledge.”<br />
<br />
=== Joe Kileel (Princeton) ===<br />
<br />
Title: Inverse Problems, Imaging and Tensor Decomposition<br />
<br />
Abstract: Perspectives from computational algebra and optimization are brought <br />
to bear on a scientific application and a data science application. <br />
In the first part of the talk, I will discuss cryo-electron microscopy <br />
(cryo-EM), an imaging technique to determine the 3-D shape of <br />
macromolecules from many noisy 2-D projections, recognized by the 2017 <br />
Chemistry Nobel Prize. Mathematically, cryo-EM presents a <br />
particularly rich inverse problem, with unknown orientations, extreme <br />
noise, big data and conformational heterogeneity. In particular, this <br />
motivates a general framework for statistical estimation under compact <br />
group actions, connecting information theory and group invariant <br />
theory. In the second part of the talk, I will discuss tensor rank <br />
decomposition, a higher-order variant of PCA broadly applicable in <br />
data science. A fast algorithm is introduced and analyzed, combining <br />
ideas of Sylvester and the power method.<br />
<br />
=== Cynthia Vinzant (NCSU) ===<br />
<br />
Title: Matroids, log-concavity, and expanders<br />
<br />
Abstract: Matroids are combinatorial objects that model various types of independence. They appear several fields mathematics, including graph theory, combinatorial optimization, and algebraic geometry. In this talk, I will introduce the theory of matroids along with the closely related class of polynomials called strongly log-concave polynomials. Strong log-concavity is a functional property of a real multivariate polynomial that translates to useful conditions on its coefficients. Discrete probability distributions defined by these coefficients inherit several of these nice properties. I will discuss the beautiful real and combinatorial geometry underlying these polynomials and describe applications to random walks on the faces of simplicial complexes. Consequences include proofs of Mason's conjecture that the sequence of numbers of independent sets of a matroid is ultra log-concave and the Mihail-Vazirani conjecture that the basis exchange graph of a matroid has expansion at least one. This is based on joint work with Nima Anari, Kuikui Liu, and Shayan Oveis Gharan.<br />
<br />
== Future Colloquia ==<br />
[[Colloquia/Fall 2020| Fall 2020]]<br />
<br />
== Past Colloquia ==<br />
<br />
[[Colloquia/Blank|Blank]]<br />
<br />
[[Colloquia/Spring2019|Spring 2019]]<br />
<br />
[[Colloquia/Fall2018|Fall 2018]]<br />
<br />
[[Colloquia/Spring2018|Spring 2018]]<br />
<br />
[[Colloquia/Fall2017|Fall 2017]]<br />
<br />
[[Colloquia/Spring2017|Spring 2017]]<br />
<br />
[[Archived Fall 2016 Colloquia|Fall 2016]]<br />
<br />
[[Colloquia/Spring2016|Spring 2016]]<br />
<br />
[[Colloquia/Fall2015|Fall 2015]]<br />
<br />
[[Colloquia/Spring2014|Spring 2015]]<br />
<br />
[[Colloquia/Fall2014|Fall 2014]]<br />
<br />
[[Colloquia/Spring2014|Spring 2014]]<br />
<br />
[[Colloquia/Fall2013|Fall 2013]]<br />
<br />
[[Colloquia 2012-2013|Spring 2013]]<br />
<br />
[[Colloquia 2012-2013#Fall 2012|Fall 2012]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Colloquia/Spring2020&diff=18872Colloquia/Spring20202020-02-03T17:32:48Z<p>Spagnolie: /* Spring 2020 */</p>
<hr />
<div>= Mathematics Colloquium =<br />
<br />
All colloquia are on Fridays at 4:00 pm in Van Vleck B239, '''unless otherwise indicated'''.<br />
<br />
<br />
<br />
==Fall 2019==<br />
{| cellpadding="8"<br />
!align="left" | date <br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
|Sept 6 '''Room 911'''<br />
| Will Sawin (Columbia)<br />
| [[#Will Sawin (Columbia) | On Chowla's Conjecture over F_q[T] ]]<br />
| Marshall<br />
|-<br />
|Sept 13<br />
| [https://www.math.ksu.edu/~soibel/ Yan Soibelman] (Kansas State)<br />
|[[#Yan Soibelman (Kansas State)| Riemann-Hilbert correspondence and Fukaya categories ]]<br />
| Caldararu<br />
|<br />
|-<br />
|Sept 16 '''Monday Room 911'''<br />
| [http://mate.dm.uba.ar/~alidick/ Alicia Dickenstein] (Buenos Aires)<br />
|[[#Alicia Dickenstein (Buenos Aires)| Algebra and geometry in the study of enzymatic cascades ]]<br />
| Craciun<br />
|<br />
|-<br />
|Sept 20<br />
| [https://math.duke.edu/~jianfeng/ Jianfeng Lu] (Duke)<br />
|[[#Jianfeng Lu (Duke) | How to "localize" the computation?]]<br />
| Qin<br />
|<br />
|-<br />
|Sept 26 '''Thursday 3-4 pm Room 911'''<br />
| [http://eugeniacheng.com/ Eugenia Cheng] (School of the Art Institute of Chicago)<br />
| [[#Eugenia Cheng (School of the Art Institute of Chicago)| Character vs gender in mathematics and beyond ]]<br />
| Marshall / Friends of UW Madison Libraries<br />
|<br />
|-<br />
|Sept 27<br />
|<br />
|<br />
|-<br />
|Oct 4<br />
|<br />
|<br />
|-<br />
|Oct 11<br />
| Omer Mermelstein (Madison)<br />
| [[#Omer Mermelstein (Madison)| Generic flat pregeometries ]]<br />
|Andrews<br />
|<br />
|-<br />
|Oct 18<br />
| Shamgar Gurevich (Madison)<br />
| [[#Shamgar Gurevich (Madison) | Harmonic Analysis on GL(n) over Finite Fields ]]<br />
| Marshall<br />
|-<br />
|Oct 25<br />
|<br />
|-<br />
|Nov 1<br />
|Elchanan Mossel (MIT)<br />
|Distinguished Lecture<br />
|Roch<br />
|-<br />
|Nov 8<br />
|Jose Rodriguez (UW-Madison)<br />
|[[#Jose Rodriguez (UW-Madison) | Nearest Point Problems and Euclidean Distance Degrees]]<br />
|Erman<br />
|-<br />
|Nov 13 '''Wednesday 4-5pm'''<br />
|Ananth Shankar (MIT)<br />
|Exceptional splitting of abelian surfaces<br />
|-<br />
|Nov 20 '''Wednesday 4-5pm'''<br />
|Franca Hoffman (Caltech)<br />
|[[#Franca Hoffman (Caltech) | Gradient Flows: From PDE to Data Analysis]]<br />
|Smith<br />
|-<br />
|Nov 22<br />
| Jeffrey Danciger (UT Austin)<br />
| [[#Jeffrey Danciger (UT Austin) | "Affine geometry and the Auslander Conjecture"]]<br />
| Kent<br />
|-<br />
|Nov 25 '''Monday 4-5 pm Room 911'''<br />
|Tatyana Shcherbina (Princeton)<br />
| [[# Tatyana Shcherbina (Princeton)| "Random matrix theory and supersymmetry techniques"]]<br />
|Roch<br />
|-<br />
|Nov 29<br />
|Thanksgiving<br />
|<br />
|-<br />
|Dec 2 '''Monday 4-5pm'''<br />
|Tingran Gao (University of Chicago)<br />
| [[#Tingran Gao (University of Chicago)| "Manifold Learning on Fibre Bundles"]]<br />
|Smith<br />
|-<br />
|Dec 4 '''Wednesday 4-5 pm Room 911'''<br />
|Andrew Zimmer (LSU)<br />
|[[#Andrew Zimmer (LSU)| "Intrinsic and extrinsic geometries in several complex variables"]]<br />
|Gong<br />
|-<br />
|Dec 6<br />
|Charlotte Chan (MIT)<br />
|[[#Charlotte Chan (MIT)|"Flag varieties and representations of p-adic groups"]]<br />
|Erman<br />
|-<br />
|Dec 9 '''Monday 4-5 pm'''<br />
|Hui Yu (Columbia)<br />
|[[#Hui Yu (Columbia)|Singular sets in obstacle problems]]<br />
|Tran<br />
|-<br />
|Dec 11 '''Wednesday 2:30-3:30pm Room 911'''<br />
|Alex Waldron (Michigan)<br />
|[[#Alex Waldron (Michigan)|Gauge theory and geometric flows]]<br />
|Paul<br />
|-<br />
|Dec 11 '''Wednesday 4-5pm'''<br />
|Nick Higham (Manchester)<br />
|[[#Nick Higham (Manchester)|LAA lecture: Challenges in Multivalued Matrix Functions]]<br />
|Brualdi<br />
|-<br />
|Dec 13 <br />
|Chenxi Wu (Rutgers)<br />
|[[#Chenxi Wu (Rutgers)|Kazhdan's theorem on metric graphs]]<br />
|Ellenberg<br />
|-<br />
|Dec 18 '''Wednesday 4-5pm'''<br />
|Ruobing Zhang (Stony Brook)<br />
|[[#Ruobing Zhang (Stony Brook)|Geometry and analysis of degenerating Calabi-Yau manifolds]]<br />
|Paul<br />
|-<br />
|}<br />
<br />
==Spring 2020==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date <br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|<br />
|-<br />
|Jan 10<br />
|Thomas Lam (Michigan) <br />
|[[#Thomas Lam (Michigan) |Positive geometries and string theory amplitudes]]<br />
|Erman<br />
|-<br />
|Jan 21 '''Tuesday 4-5 pm in B139'''<br />
|[http://www.nd.edu/~cholak/ Peter Cholak] (Notre Dame) <br />
|[[#Peter Cholak (Notre Dame) |What can we compute from solutions to combinatorial problems?]]<br />
|Lempp<br />
|-<br />
|Jan 24<br />
|[https://math.duke.edu/people/saulo-orizaga Saulo Orizaga] (Duke)<br />
|[[#Saulo Orizaga (Duke) | Introduction to phase field models and their efficient numerical implementation ]]<br />
|<br />
|-<br />
|Jan 27 '''Monday 4-5 pm in 911'''<br />
|[https://math.yale.edu/people/caglar-uyanik Caglar Uyanik] (Yale)<br />
|[[#Caglar Uyanik (Yale) | Hausdorff dimension and gap distribution in billiards ]]<br />
|Ellenberg<br />
|-<br />
|Jan 29 '''Wednesday 4-5 pm'''<br />
|[https://ajzucker.wordpress.com/ Andy Zucker] (Lyon)<br />
|[[#Andy Zucker (Lyon) |Topological dynamics of countable groups and structures]]<br />
|Soskova/Lempp<br />
|-<br />
|Jan 31 <br />
|[https://services.math.duke.edu/~pierce/ Lillian Pierce] (Duke)<br />
|[[#Lillian Pierce (Duke) |On Bourgain’s counterexample for the Schrödinger maximal function]]<br />
|Marshall/Seeger<br />
|-<br />
|Feb 7<br />
|[https://web.math.princeton.edu/~jkileel/ Joe Kileel] (Princeton)<br />
|[[#Joe Kileel (Princeton) |Inverse Problems, Imaging and Tensor Decomposition]]<br />
|Roch<br />
|-<br />
|Feb 10<br />
|[https://clvinzan.math.ncsu.edu/ Cynthia Vinzant] (NCSU)<br />
|[[#Cynthia Vinzant (NCSU) |Matroids, log-concavity, and expanders]]<br />
|Roch/Erman<br />
|-<br />
|Feb 12 '''Wednesday 4-5 pm'''<br />
|[https://www.machuang.org/ Jinzi Mac Huang] (UCSD)<br />
|[[#Jinzi Mac Huang (UCSD) |Math in the lab: mass transfer through fluid-structure interactions]]<br />
|Spagnolie<br />
|-<br />
|Feb 14<br />
|Reserved for job talk<br />
|<br />
|-<br />
|Feb 21<br />
|Shai Evra (IAS)<br />
|<br />
|Gurevich<br />
|<br />
|-<br />
|Feb 28<br />
|Brett Wick (Washington University, St. Louis)<br />
|<br />
|Seeger<br />
|-<br />
|March 6<br />
| Jessica Fintzen (Michigan)<br />
|<br />
|Marshall<br />
|-<br />
|March 13<br />
|<br />
|-<br />
|March 20<br />
|Spring break<br />
|<br />
|-<br />
|March 27<br />
|(Moduli Spaces Conference)<br />
|<br />
|Boggess, Sankar<br />
|-<br />
|April 3<br />
|Caroline Turnage-Butterbaugh (Carleton College)<br />
|<br />
|Marshall<br />
|-<br />
|April 10<br />
| Sarah Koch (Michigan)<br />
|<br />
| Bruce (WIMAW)<br />
|-<br />
|April 17<br />
|<br />
|<br />
|<br />
|-<br />
|April 23<br />
|Martin Hairer (Imperial College London)<br />
|Wolfgang Wasow Lecture<br />
|Hao Shen<br />
|-<br />
|April 24<br />
|Natasa Sesum (Rutgers University)<br />
|<br />
|Angenent<br />
|-<br />
|May 1<br />
|Robert Lazarsfeld (Stony Brook)<br />
|Distinguished lecture<br />
|Erman<br />
|}<br />
<br />
== Abstracts ==<br />
<br />
<br />
===Will Sawin (Columbia)===<br />
<br />
Title: On Chowla's Conjecture over F_q[T]<br />
<br />
Abstract: The Mobius function in number theory is a sequences of 1s, <br />
-1s, and 0s, which is simple to define and closely related to the <br />
prime numbers. Its behavior seems highly random. Chowla's conjecture <br />
is one precise formalization of this randomness, and has seen recent <br />
work by Matomaki, Radziwill, Tao, and Teravainen making progress on <br />
it. In joint work with Mark Shusterman, we modify this conjecture by <br />
replacing the natural numbers parameterizing this sequence with <br />
polynomials over a finite field. Under mild conditions on the finite <br />
field, we are able to prove a strong form of this conjecture. The <br />
proof is based on taking a geometric perspective on the problem, and <br />
succeeds because we are able to simplify the geometry using a trick <br />
based on the strange properties of polynomial derivatives over finite <br />
fields.<br />
<br />
<br />
===Yan Soibelman (Kansas State)===<br />
<br />
Title: Riemann-Hilbert correspondence and Fukaya categories<br />
<br />
Abstract: In this talk I am going to discuss the role of Fukaya categories in the Riemann-Hilbert correspondence<br />
for differential, q-difference and elliptic difference equations in dimension one.<br />
This approach not only gives a unified answer for several versions of the Riemann-Hilbert correspondence but also leads to a natural formulation<br />
of the non-abelian Hodge theory in dimension one. It also explains why periodic monopoles<br />
should appear as harmonic objects in this generalized non-abelian Hodge theory.<br />
All that is a part of the bigger project ``Holomorphic Floer theory",<br />
joint with Maxim Kontsevich.<br />
<br />
<br />
===Alicia Dickenstein (Buenos Aires)===<br />
<br />
Title: Algebra and geometry in the study of enzymatic cascades<br />
<br />
Abstract: In recent years, techniques from computational and real algebraic geometry have been successfully used to address mathematical challenges in systems biology. The algebraic theory of chemical reaction systems aims to understand their dynamic behavior by taking advantage of the inherent algebraic structure in the kinetic equations, and does not need the determination of the parameters a priori, which can be theoretically or practically impossible.<br />
I will give a gentle introduction to general results based on the network structure. In particular, I will describe a general framework for biological systems, called MESSI systems, that describe Modifications of type Enzyme-Substrate or Swap with Intermediates, and include many networks that model post-translational modifications of proteins inside the cell. I will also outline recent methods to address the important question of multistationarity, in particular in the study of enzymatic cascades, and will point out some of the mathematical challenges that arise from this application.<br />
<br />
<br />
=== Jianfeng Lu (Duke) ===<br />
Title: How to ``localize" the computation?<br />
<br />
It is often desirable to restrict the numerical computation to a local region to achieve best balance between accuracy and affordability in scientific computing. It is important to avoid artifacts and guarantee predictable modelling while artificial boundary conditions have to be introduced to restrict the computation. In this talk, we will discuss some recent understanding on how to achieve such local computation in the context of topological edge states and elliptic random media.<br />
<br />
<br />
===Eugenia Cheng (School of the Art Institute of Chicago)===<br />
<br />
Title: Character vs gender in mathematics and beyond<br />
<br />
Abstract: This presentation will be based on my experience of being a female mathematician, and teaching mathematics at all levels from elementary school to grad school. The question of why women are under-represented in mathematics is complex and there are no simple answers, only many many contributing factors. I will focus on character traits, and argue that if we focus on this rather than gender we can have a more productive and less divisive conversation. To try and focus on characters rather than genders I will introduce gender-neutral character adjectives "ingressive" and "congressive" to replace masculine and feminine. I will share my experience of teaching congressive abstract mathematics to art students, in a congressive way, and the possible effects this could have for everyone in mathematics, not just women.<br />
<br />
<br />
===Omer Mermelstein (Madison)===<br />
<br />
Title: Generic flat pregeometries<br />
<br />
Abstract: In model theory, the tamest of structures are the strongly minimal ones -- those in which every equation in a single variable has either finitely many or cofinitely many solution. Algebraically closed fields and vector spaces are the canonical examples. Zilber’s conjecture, later refuted by Hrushovski, states that the source of geometric complexity in a strongly minimal structure must be algebraic. The property of "flatness" (strict gammoid) of a geometry (matroid) is that which guarantees Hrushovski's construction is devoid of any associative structure.<br />
The majority of the talk will explain what flatness is, how it should be thought of, and how closely it relates to hypergraphs and Hrushovski's construction method. Model theory makes an appearance only in the second part, where I will share results pertaining to the specific family of geometries arising from Hrushovski's methods.<br />
<br />
<br />
===Shamgar Gurevich (Madison)===<br />
<br />
Title: Harmonic Analysis on GL(n) over Finite Fields.<br />
<br />
Abstract: There are many formulas that express interesting properties of a finite group G in terms of sums over its characters. For evaluating or estimating these sums, one of the most salient quantities to understand is the character ratio:<br />
<br />
trace(ρ(g)) / dim(ρ),<br />
<br />
for an irreducible representation ρ of G and an element g of G. For example, Diaconis and Shahshahani stated a formula of the mentioned type for analyzing certain random walks on G.<br />
<br />
Recently, we discovered that for classical groups G over finite fields there is a natural invariant of representations that provides strong information on the character ratio. We call this invariant rank. <br />
<br />
This talk will discuss the notion of rank for the group GLn over finite fields, demonstrate how it controls the character ratio, and explain how one can apply the results to verify mixing time and rate for certain random walks.<br />
<br />
This is joint work with Roger Howe (Yale and Texas AM). The numerics for this work was carried by Steve Goldstein (Madison)<br />
<br />
<br />
===Jose Rodriguez (UW-Madison)===<br />
<br />
Abstract: Determining the closest point to a model (subset of Euclidean space) is an important problem in many applications in science,<br />
engineering, and statistics. One way to solve this problem is by minimizing the squared Euclidean distance function using a gradient<br />
descent approach. However, when there are multiple local minima, there is no guarantee of convergence to the true global minimizer.<br />
An alternative method is to determine the critical points of an objective function on the model.<br />
In algebraic statistics, the models of interest are algebraic sets, i.e., solution sets to a system of multivariate polynomial equations. In this situation, the number of critical points of the squared Euclidean distance function on the model’s Zariski closure is a topological invariant called the Euclidean distance degree (ED degree).<br />
In this talk, I will present some models from computer vision and statistics that may be described as algebraic sets. Moreover,<br />
I will describe a topological method for determining a Euclidean distance degree and a numerical algebraic geometry approach for<br />
determining critical points of the squared Euclidean distance function.<br />
<br />
<br />
===Ananth Shankar (MIT)===<br />
<br />
Abstract: An abelian surface 'splits' if it admits a non-trivial map to some elliptic curve. It is well known that the set of abelian surfaces that split are sparse in the set of all abelian surfaces. Nevertheless, we prove that there are infinitely many split abelian surfaces in arithmetic one-parameter families of generically non-split abelian surfaces. I will describe this work, and if time permits, mention generalizations of this result to the setting of K3 surfaces, as well as applications to the dynamics of hecke orbits. This is joint work with Tang, Maulik-Tang, and Shankar-Tang-Tayou.<br />
<br />
<br />
===Franca Hoffman (Caltech)===<br />
<br />
Title: Gradient Flows: From PDE to Data Analysis.<br />
<br />
Abstract: Certain diffusive PDEs can be viewed as infinite-dimensional gradient flows. This fact has led to the development of new tools in various areas of mathematics ranging from PDE theory to data science. In this talk, we focus on two different directions: model-driven approaches and data-driven approaches.<br />
In the first part of the talk we use gradient flows for analyzing non-linear and non-local aggregation-diffusion equations when the corresponding energy functionals are not necessarily convex. Moreover, the gradient flow structure enables us to make connections to well-known functional inequalities, revealing possible links between the optimizers of these inequalities and the equilibria of certain aggregation-diffusion PDEs.<br />
In the second part, we use and develop gradient flow theory to design novel tools for data analysis. We draw a connection between gradient flows and Ensemble Kalman methods for parameter estimation. We introduce the Ensemble Kalman Sampler - a derivative-free methodology for model calibration and uncertainty quantification in expensive black-box models. The interacting particle dynamics underlying our algorithm can be approximated by a novel gradient flow structure in a modified Wasserstein metric which reflects particle correlations. The geometry of this modified Wasserstein metric is of independent theoretical interest.<br />
<br />
<br />
=== Jeffrey Danciger (UT Austin) ===<br />
<br />
Title: Affine geometry and the Auslander Conjecture<br />
<br />
Abstract: The Auslander Conjecture is an analogue of Bieberbach’s theory of Euclidean crystallographic groups in the setting of affine geometry. It predicts that a complete affine manifold (a manifold equipped with a complete torsion-free flat affine connection) which is compact must have virtually solvable fundamental group. The conjecture is known up to dimension six, but is known to fail if the compactness assumption is removed, even in low dimensions. We discuss some history of this conjecture, give some basic examples, and then survey some recent advances in the study of non-compact complete affine manifolds with non-solvable fundamental group. <br />
Tools from the deformation theory of pseudo-Riemannian hyperbolic manifolds and also from higher Teichm&uuml;ller theory will enter the picture.<br />
<br />
<br />
=== Tatyana Shcherbina (Princeton) ===<br />
<br />
Title: Random matrix theory and supersymmetry techniques<br />
<br />
Abstract: Starting from the works of Erdos, Yau, Schlein with coauthors, the significant progress in understanding the universal behavior of many random graph and random matrix models were achieved. However for the random matrices with a special structure our understanding is still very limited. In this talk I am going to overview applications of another approach to the study of the local eigenvalues statistics in random matrix theory based on so-called supersymmetry techniques (SUSY). SUSY approach is based on the representation of the determinant as an integral over the Grassmann (anticommuting) variables. Combining this representation with the representation of an inverse determinant as an integral over the Gaussian complex field, SUSY allows to obtain an integral representation for the main spectral characteristics of random matrices such as limiting density, correlation functions, the resolvent's elements, etc. This method is widely (and successfully) used in the physics literature and is potentially very powerful but the rigorous control of the integral representations, which can be obtained by this method, is quite difficult, and it requires powerful analytic and statistical mechanics tools. In this talk we will discuss some recent progress in application of SUSY to the analysis of local spectral characteristics of the prominent ensemble of random band matrices, i.e. random matrices<br />
whose entries become negligible if their distance from the main diagonal exceeds a certain parameter called the band width. <br />
<br />
<br />
=== Tingran Gao (University of Chicago) ===<br />
<br />
Title: Manifold Learning on Fibre Bundles<br />
<br />
Abstract: Spectral geometry has played an important role in modern geometric data analysis, where the technique is widely known as Laplacian eigenmaps or diffusion maps. In this talk, we present a geometric framework that studies graph representations of complex datasets, where each edge of the graph is equipped with a non-scalar transformation or correspondence. This new framework models such a dataset as a fibre bundle with a connection, and interprets the collection of pairwise functional relations as defining a horizontal diffusion process on the bundle driven by its projection on the base. The eigenstates of this horizontal diffusion process encode the “consistency” among objects in the dataset, and provide a lens through which the geometry of the dataset can be revealed. We demonstrate an application of this geometric framework on evolutionary anthropology.<br />
<br />
<br />
=== Andrew Zimmer (LSU) ===<br />
<br />
Title: Intrinsic and extrinsic geometries in several complex variables<br />
<br />
Abstract: A bounded domain in complex Euclidean space, despite being one of the simplest types of manifolds, has a number of interesting geometric structures. When the domain is pseudoconvex, it has a natural intrinsic geometry: the complete Kaehler-Einstein metric constructed by Cheng-Yau and Mok-Yau. When the domain is smoothly bounded, there is also a natural extrinsic structure: the CR-geometry of the boundary. In this talk, I will describe connections between these intrinsic and extrinsic geometries. Then, I will discuss how these connections can lead to new analytic results.<br />
<br />
=== Charlotte Chan (MIT) ===<br />
<br />
Title: Flag varieties and representations of p-adic groups<br />
<br />
Abstract: In the 1950s, Borel, Weil, and Bott showed that the<br />
irreducible representations of a complex reductive group can be<br />
realized in the cohomology of line bundles on flag varieties. In the<br />
1970s, Deligne and Lusztig constructed a family of subvarieties of<br />
flag varieties whose cohomology realizes the irreducible<br />
representations of reductive groups over finite fields. I will survey<br />
these stories, explain recent progress towards finding geometric<br />
constructions of representations of p-adic groups, and discuss<br />
interactions with the Langlands program.<br />
<br />
=== Hui Yu (Columbia) ===<br />
<br />
Title: Singular sets in obstacle problems<br />
<br />
Abstract: One of the most important free boundary problems is the obstacle problem. The regularity of its free boundary has been studied for over half a century. In this talk, we review some classical results as well as exciting new developments. In particular, we discuss the recent resolution of the regularity of the singular set for the fully nonlinear obstacle problem. This talk is based on a joint work with Ovidiu Savin at Columbia University.<br />
<br />
=== Alex Waldron (Michigan) ===<br />
<br />
Title: Gauge theory and geometric flows<br />
<br />
Abstract: I will give a brief introduction to two major areas of research in differential geometry: gauge theory and geometric flows. I'll then introduce a geometric flow (Yang-Mills flow) arising from a variational problem with origins in physics, which has been studied by geometric analysts since the early 1980s. I'll conclude by discussing my own work on the behavior of Yang-Mills flow in the critical dimension (n = 4).<br />
<br />
=== Nick Higham (Manchester) ===<br />
<br />
Title: Challenges in Multivalued Matrix Functions<br />
<br />
Abstract: In this lecture I will discuss multivalued matrix functions that arise in solving various kinds of matrix equations. The matrix logarithm is the prototypical example, and my first interaction with Hans Schneider was about this function. Another example is the Lambert W function of a matrix, which is much less well known but has been attracting recent interest. A theme of the talk is the importance of choosing appropriate principal values and making sure that the correct choices of signs and branches are used,<br />
both in theory and in computation. I will give examples where incorrect results have previously been obtained.<br />
<br />
I focus on matrix inverse trigonometric and inverse hyperbolic functions, beginning by investigating existence and characterization. Turning to the principal values, various functional identities are derived, some of which are new even in the scalar case, including a “round trip” formula that relates acos(cos A) to A and similar formulas for the other inverse functions. Key tools used in the derivations are the matrix unwinding function and the matrix sign function.<br />
<br />
A new inverse scaling and squaring type algorithm employing a Schur decomposition and variable-degree Pade approximation is derived for computing acos, and it is shown how it can also be used to compute asin, acosh, and asinh.<br />
<br />
=== Chenxi Wu (Rutgers) ===<br />
<br />
Title: Kazhdan's theorem on metric graphs<br />
<br />
Abstract: I will give an introduction to the concept of canonical (arakelov) metric on a metric graph, which is related to combinatorial questions like the counting of spanning trees, and generalizes the corresponding concept on Riemann surfaces. I will also present a recent result in collaboration with Farbod Shokrieh on the convergence of canonical metric under normal covers.<br />
<br />
=== Ruobing Zhang (Stony Brook) ===<br />
<br />
Title: Geometry and analysis of degenerating Calabi-Yau manifolds<br />
<br />
Abstract: This talk concerns a naturally occurring family of degenerating Calabi-Yau manifolds. A primary tool in analyzing their behavior is to combine the recently developed structure theory for Einstein manifolds and multi-scale singularity analysis for degenerating nonlinear PDEs in the collapsed setting. Based on the algebraic degeneration, we will give precise and more quantitative descriptions of singularity formation from both metric and analytic points of view.<br />
<br />
=== Thomas Lam (Michigan) === <br />
<br />
Title: Positive geometries and string theory amplitudes<br />
<br />
Abstract: Inspired by developments in quantum field theory, we<br />
recently defined the notion of a positive geometry, a class of spaces<br />
that includes convex polytopes, positive parts of projective toric<br />
varieties, and positive parts of flag varieties. I will discuss some<br />
basic features of the theory and an application to genus zero string<br />
theory amplitudes. As a special case, we obtain the Euler beta<br />
function, familiar to mathematicians, as the "stringy canonical form"<br />
of the closed interval.<br />
<br />
This talk is based on joint work with Arkani-Hamed, Bai, and He.<br />
<br />
=== Peter Cholak (Notre Dame) ===<br />
<br />
Title: What can we compute from solutions to combinatorial problems?<br />
<br />
Abstract: This will be an introductory talk to an exciting current <br />
research area in mathematical logic. Mostly we are interested in <br />
solutions to Ramsey's Theorem. Ramsey's Theorem says for colorings <br />
C of pairs of natural numbers, there is an infinite set H such that <br />
all pairs from H have the same constant color. H is called a homogeneous <br />
set for C. What can we compute from H? If you are not sure, come to <br />
the talk and find out!<br />
<br />
=== Saulo Orizaga (Duke) ===<br />
<br />
Title: Introduction to phase field models and their efficient numerical implementation<br />
<br />
Abstract: In this talk we will provide an introduction to phase field models. We will focus in models<br />
related to the Cahn-Hilliard (CH) type of partial differential equation (PDE). We will discuss the<br />
challenges associated in solving such higher order parabolic problems. We will present several<br />
new numerical methods that are fast and efficient for solving CH or CH-extended type of problems.<br />
The new methods and their energy-stability properties will be discussed and tested with several computational examples commonly found in material science problems. If time allows, we will talk about more applications in which phase field models are useful and applicable.<br />
<br />
=== Caglar Uyanik (Yale) ===<br />
<br />
Title: Hausdorff dimension and gap distribution in billiards<br />
<br />
Abstract: A classical “unfolding” procedure allows one to turn questions about billiard trajectories in a Euclidean polygon into questions about the geodesic flow on a surface equipped with a certain geometric structure. Surprisingly, the flow on the surface is in turn related to the geodesic flow on the classical moduli spaces of Riemann surfaces. Building on recent breakthrough results of Eskin-Mirzakhani-Mohammadi, we prove a large deviations result for Birkhoff averages as well as generalize a classical theorem of Masur on geodesics in the moduli spaces of translation surfaces. <br />
<br />
=== Andy Zucker (Lyon) ===<br />
<br />
Title: Topological dynamics of countable groups and structures<br />
<br />
Abstract: We give an introduction to the abstract topological dynamics <br />
of topological groups, i.e. the study of the continuous actions of a <br />
topological group on a compact space. We are particularly interested <br />
in the minimal actions, those for which every orbit is dense. <br />
The study of minimal actions is aided by a classical theorem of Ellis, <br />
who proved that for any topological group G, there exists a universal <br />
minimal flow (UMF), a minimal G-action which factors onto every other <br />
minimal G-action. Here, we will focus on two classes of groups: <br />
a countable discrete group and the automorphism group of a countable <br />
first-order structure. In the case of a countable discrete group, <br />
Baire category methods can be used to show that the collection of <br />
minimal flows is quite rich and that the UMF is rather complicated. <br />
For an automorphism group G of a countable structure, combinatorial <br />
methods can be used to show that sometimes, the UMF is trivial, or <br />
equivalently that every continuous action of G on a compact space <br />
admits a global fixed point.<br />
<br />
=== Lillian Pierce (Duke) ===<br />
<br />
Title: On Bourgain’s counterexample for the Schrödinger maximal function<br />
<br />
Abstract: In 1980, Carleson asked a question in harmonic analysis: to which Sobolev space $H^s$ must an initial data function belong, for a pointwise a.e. convergence result to hold for the solution to the associated linear Schrödinger equation? Over the next decades, many people developed counterexamples to push the (necessary) range of s up, and positive results to push the (sufficient) range of s down. Now, these ranges are finally meeting: Bourgain’s 2016 counterexample showed s < n/(2(n+1)) fails, and Du and Zhang’s 2019 paper shows that s>n/(2(n+1)) suffices. <br />
In this talk, we will give an overview of how to rigorously derive Bourgain’s 2016 counterexample, based on simple facts from number theory. We will show how to build Bourgain’s counterexample starting from “zero knowledge," and how to gradually optimize the set-up to arrive at the final counterexample. The talk will be broadly accessible, particularly if we live up to the claim of starting from “zero knowledge.”<br />
<br />
=== Joe Kileel (Princeton) ===<br />
<br />
Title: Inverse Problems, Imaging and Tensor Decomposition<br />
<br />
Abstract: Perspectives from computational algebra and optimization are brought <br />
to bear on a scientific application and a data science application. <br />
In the first part of the talk, I will discuss cryo-electron microscopy <br />
(cryo-EM), an imaging technique to determine the 3-D shape of <br />
macromolecules from many noisy 2-D projections, recognized by the 2017 <br />
Chemistry Nobel Prize. Mathematically, cryo-EM presents a <br />
particularly rich inverse problem, with unknown orientations, extreme <br />
noise, big data and conformational heterogeneity. In particular, this <br />
motivates a general framework for statistical estimation under compact <br />
group actions, connecting information theory and group invariant <br />
theory. In the second part of the talk, I will discuss tensor rank <br />
decomposition, a higher-order variant of PCA broadly applicable in <br />
data science. A fast algorithm is introduced and analyzed, combining <br />
ideas of Sylvester and the power method.<br />
<br />
=== Cynthia Vinzant (NCSU) ===<br />
<br />
Title: Matroids, log-concavity, and expanders<br />
<br />
Abstract: Matroids are combinatorial objects that model various types of independence. They appear several fields mathematics, including graph theory, combinatorial optimization, and algebraic geometry. In this talk, I will introduce the theory of matroids along with the closely related class of polynomials called strongly log-concave polynomials. Strong log-concavity is a functional property of a real multivariate polynomial that translates to useful conditions on its coefficients. Discrete probability distributions defined by these coefficients inherit several of these nice properties. I will discuss the beautiful real and combinatorial geometry underlying these polynomials and describe applications to random walks on the faces of simplicial complexes. Consequences include proofs of Mason's conjecture that the sequence of numbers of independent sets of a matroid is ultra log-concave and the Mihail-Vazirani conjecture that the basis exchange graph of a matroid has expansion at least one. This is based on joint work with Nima Anari, Kuikui Liu, and Shayan Oveis Gharan.<br />
<br />
== Future Colloquia ==<br />
[[Colloquia/Fall 2020| Fall 2020]]<br />
<br />
== Past Colloquia ==<br />
<br />
[[Colloquia/Blank|Blank]]<br />
<br />
[[Colloquia/Spring2019|Spring 2019]]<br />
<br />
[[Colloquia/Fall2018|Fall 2018]]<br />
<br />
[[Colloquia/Spring2018|Spring 2018]]<br />
<br />
[[Colloquia/Fall2017|Fall 2017]]<br />
<br />
[[Colloquia/Spring2017|Spring 2017]]<br />
<br />
[[Archived Fall 2016 Colloquia|Fall 2016]]<br />
<br />
[[Colloquia/Spring2016|Spring 2016]]<br />
<br />
[[Colloquia/Fall2015|Fall 2015]]<br />
<br />
[[Colloquia/Spring2014|Spring 2015]]<br />
<br />
[[Colloquia/Fall2014|Fall 2014]]<br />
<br />
[[Colloquia/Spring2014|Spring 2014]]<br />
<br />
[[Colloquia/Fall2013|Fall 2013]]<br />
<br />
[[Colloquia 2012-2013|Spring 2013]]<br />
<br />
[[Colloquia 2012-2013#Fall 2012|Fall 2012]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Colloquia/Spring2020&diff=18871Colloquia/Spring20202020-02-03T17:32:26Z<p>Spagnolie: /* Spring 2020 */</p>
<hr />
<div>= Mathematics Colloquium =<br />
<br />
All colloquia are on Fridays at 4:00 pm in Van Vleck B239, '''unless otherwise indicated'''.<br />
<br />
<br />
<br />
==Fall 2019==<br />
{| cellpadding="8"<br />
!align="left" | date <br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
|Sept 6 '''Room 911'''<br />
| Will Sawin (Columbia)<br />
| [[#Will Sawin (Columbia) | On Chowla's Conjecture over F_q[T] ]]<br />
| Marshall<br />
|-<br />
|Sept 13<br />
| [https://www.math.ksu.edu/~soibel/ Yan Soibelman] (Kansas State)<br />
|[[#Yan Soibelman (Kansas State)| Riemann-Hilbert correspondence and Fukaya categories ]]<br />
| Caldararu<br />
|<br />
|-<br />
|Sept 16 '''Monday Room 911'''<br />
| [http://mate.dm.uba.ar/~alidick/ Alicia Dickenstein] (Buenos Aires)<br />
|[[#Alicia Dickenstein (Buenos Aires)| Algebra and geometry in the study of enzymatic cascades ]]<br />
| Craciun<br />
|<br />
|-<br />
|Sept 20<br />
| [https://math.duke.edu/~jianfeng/ Jianfeng Lu] (Duke)<br />
|[[#Jianfeng Lu (Duke) | How to "localize" the computation?]]<br />
| Qin<br />
|<br />
|-<br />
|Sept 26 '''Thursday 3-4 pm Room 911'''<br />
| [http://eugeniacheng.com/ Eugenia Cheng] (School of the Art Institute of Chicago)<br />
| [[#Eugenia Cheng (School of the Art Institute of Chicago)| Character vs gender in mathematics and beyond ]]<br />
| Marshall / Friends of UW Madison Libraries<br />
|<br />
|-<br />
|Sept 27<br />
|<br />
|<br />
|-<br />
|Oct 4<br />
|<br />
|<br />
|-<br />
|Oct 11<br />
| Omer Mermelstein (Madison)<br />
| [[#Omer Mermelstein (Madison)| Generic flat pregeometries ]]<br />
|Andrews<br />
|<br />
|-<br />
|Oct 18<br />
| Shamgar Gurevich (Madison)<br />
| [[#Shamgar Gurevich (Madison) | Harmonic Analysis on GL(n) over Finite Fields ]]<br />
| Marshall<br />
|-<br />
|Oct 25<br />
|<br />
|-<br />
|Nov 1<br />
|Elchanan Mossel (MIT)<br />
|Distinguished Lecture<br />
|Roch<br />
|-<br />
|Nov 8<br />
|Jose Rodriguez (UW-Madison)<br />
|[[#Jose Rodriguez (UW-Madison) | Nearest Point Problems and Euclidean Distance Degrees]]<br />
|Erman<br />
|-<br />
|Nov 13 '''Wednesday 4-5pm'''<br />
|Ananth Shankar (MIT)<br />
|Exceptional splitting of abelian surfaces<br />
|-<br />
|Nov 20 '''Wednesday 4-5pm'''<br />
|Franca Hoffman (Caltech)<br />
|[[#Franca Hoffman (Caltech) | Gradient Flows: From PDE to Data Analysis]]<br />
|Smith<br />
|-<br />
|Nov 22<br />
| Jeffrey Danciger (UT Austin)<br />
| [[#Jeffrey Danciger (UT Austin) | "Affine geometry and the Auslander Conjecture"]]<br />
| Kent<br />
|-<br />
|Nov 25 '''Monday 4-5 pm Room 911'''<br />
|Tatyana Shcherbina (Princeton)<br />
| [[# Tatyana Shcherbina (Princeton)| "Random matrix theory and supersymmetry techniques"]]<br />
|Roch<br />
|-<br />
|Nov 29<br />
|Thanksgiving<br />
|<br />
|-<br />
|Dec 2 '''Monday 4-5pm'''<br />
|Tingran Gao (University of Chicago)<br />
| [[#Tingran Gao (University of Chicago)| "Manifold Learning on Fibre Bundles"]]<br />
|Smith<br />
|-<br />
|Dec 4 '''Wednesday 4-5 pm Room 911'''<br />
|Andrew Zimmer (LSU)<br />
|[[#Andrew Zimmer (LSU)| "Intrinsic and extrinsic geometries in several complex variables"]]<br />
|Gong<br />
|-<br />
|Dec 6<br />
|Charlotte Chan (MIT)<br />
|[[#Charlotte Chan (MIT)|"Flag varieties and representations of p-adic groups"]]<br />
|Erman<br />
|-<br />
|Dec 9 '''Monday 4-5 pm'''<br />
|Hui Yu (Columbia)<br />
|[[#Hui Yu (Columbia)|Singular sets in obstacle problems]]<br />
|Tran<br />
|-<br />
|Dec 11 '''Wednesday 2:30-3:30pm Room 911'''<br />
|Alex Waldron (Michigan)<br />
|[[#Alex Waldron (Michigan)|Gauge theory and geometric flows]]<br />
|Paul<br />
|-<br />
|Dec 11 '''Wednesday 4-5pm'''<br />
|Nick Higham (Manchester)<br />
|[[#Nick Higham (Manchester)|LAA lecture: Challenges in Multivalued Matrix Functions]]<br />
|Brualdi<br />
|-<br />
|Dec 13 <br />
|Chenxi Wu (Rutgers)<br />
|[[#Chenxi Wu (Rutgers)|Kazhdan's theorem on metric graphs]]<br />
|Ellenberg<br />
|-<br />
|Dec 18 '''Wednesday 4-5pm'''<br />
|Ruobing Zhang (Stony Brook)<br />
|[[#Ruobing Zhang (Stony Brook)|Geometry and analysis of degenerating Calabi-Yau manifolds]]<br />
|Paul<br />
|-<br />
|}<br />
<br />
==Spring 2020==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date <br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|<br />
|-<br />
|Jan 10<br />
|Thomas Lam (Michigan) <br />
|[[#Thomas Lam (Michigan) |Positive geometries and string theory amplitudes]]<br />
|Erman<br />
|-<br />
|Jan 21 '''Tuesday 4-5 pm in B139'''<br />
|[http://www.nd.edu/~cholak/ Peter Cholak] (Notre Dame) <br />
|[[#Peter Cholak (Notre Dame) |What can we compute from solutions to combinatorial problems?]]<br />
|Lempp<br />
|-<br />
|Jan 24<br />
|[https://math.duke.edu/people/saulo-orizaga Saulo Orizaga] (Duke)<br />
|[[#Saulo Orizaga (Duke) | Introduction to phase field models and their efficient numerical implementation ]]<br />
|<br />
|-<br />
|Jan 27 '''Monday 4-5 pm in 911'''<br />
|[https://math.yale.edu/people/caglar-uyanik Caglar Uyanik] (Yale)<br />
|[[#Caglar Uyanik (Yale) | Hausdorff dimension and gap distribution in billiards ]]<br />
|Ellenberg<br />
|-<br />
|Jan 29 '''Wednesday 4-5 pm'''<br />
|[https://ajzucker.wordpress.com/ Andy Zucker] (Lyon)<br />
|[[#Andy Zucker (Lyon) |Topological dynamics of countable groups and structures]]<br />
|Soskova/Lempp<br />
|-<br />
|Jan 31 <br />
|[https://services.math.duke.edu/~pierce/ Lillian Pierce] (Duke)<br />
|[[#Lillian Pierce (Duke) |On Bourgain’s counterexample for the Schrödinger maximal function]]<br />
|Marshall/Seeger<br />
|-<br />
|Feb 7<br />
|[https://web.math.princeton.edu/~jkileel/ Joe Kileel] (Princeton)<br />
|[[#Joe Kileel (Princeton) |Inverse Problems, Imaging and Tensor Decomposition]]<br />
|Roch<br />
|-<br />
|Feb 10<br />
|[https://clvinzan.math.ncsu.edu/ Cynthia Vinzant] (NCSU)<br />
|[[#Cynthia Vinzant (NCSU) |Matroids, log-concavity, and expanders]]<br />
|Roch/Erman<br />
|-<br />
|Feb 10<br />
|[https://www.machuang.org/ Jinzi Mac Huang] (UCSD)<br />
|[[#Jinzi Mac Huang (UCSD) |Math in the lab: mass transfer through fluid-structure interactions]]<br />
|Spagnolie<br />
|-<br />
|Feb 14<br />
|Reserved for job talk<br />
|<br />
|-<br />
|Feb 21<br />
|Shai Evra (IAS)<br />
|<br />
|Gurevich<br />
|<br />
|-<br />
|Feb 28<br />
|Brett Wick (Washington University, St. Louis)<br />
|<br />
|Seeger<br />
|-<br />
|March 6<br />
| Jessica Fintzen (Michigan)<br />
|<br />
|Marshall<br />
|-<br />
|March 13<br />
|<br />
|-<br />
|March 20<br />
|Spring break<br />
|<br />
|-<br />
|March 27<br />
|(Moduli Spaces Conference)<br />
|<br />
|Boggess, Sankar<br />
|-<br />
|April 3<br />
|Caroline Turnage-Butterbaugh (Carleton College)<br />
|<br />
|Marshall<br />
|-<br />
|April 10<br />
| Sarah Koch (Michigan)<br />
|<br />
| Bruce (WIMAW)<br />
|-<br />
|April 17<br />
|<br />
|<br />
|<br />
|-<br />
|April 23<br />
|Martin Hairer (Imperial College London)<br />
|Wolfgang Wasow Lecture<br />
|Hao Shen<br />
|-<br />
|April 24<br />
|Natasa Sesum (Rutgers University)<br />
|<br />
|Angenent<br />
|-<br />
|May 1<br />
|Robert Lazarsfeld (Stony Brook)<br />
|Distinguished lecture<br />
|Erman<br />
|}<br />
<br />
== Abstracts ==<br />
<br />
<br />
===Will Sawin (Columbia)===<br />
<br />
Title: On Chowla's Conjecture over F_q[T]<br />
<br />
Abstract: The Mobius function in number theory is a sequences of 1s, <br />
-1s, and 0s, which is simple to define and closely related to the <br />
prime numbers. Its behavior seems highly random. Chowla's conjecture <br />
is one precise formalization of this randomness, and has seen recent <br />
work by Matomaki, Radziwill, Tao, and Teravainen making progress on <br />
it. In joint work with Mark Shusterman, we modify this conjecture by <br />
replacing the natural numbers parameterizing this sequence with <br />
polynomials over a finite field. Under mild conditions on the finite <br />
field, we are able to prove a strong form of this conjecture. The <br />
proof is based on taking a geometric perspective on the problem, and <br />
succeeds because we are able to simplify the geometry using a trick <br />
based on the strange properties of polynomial derivatives over finite <br />
fields.<br />
<br />
<br />
===Yan Soibelman (Kansas State)===<br />
<br />
Title: Riemann-Hilbert correspondence and Fukaya categories<br />
<br />
Abstract: In this talk I am going to discuss the role of Fukaya categories in the Riemann-Hilbert correspondence<br />
for differential, q-difference and elliptic difference equations in dimension one.<br />
This approach not only gives a unified answer for several versions of the Riemann-Hilbert correspondence but also leads to a natural formulation<br />
of the non-abelian Hodge theory in dimension one. It also explains why periodic monopoles<br />
should appear as harmonic objects in this generalized non-abelian Hodge theory.<br />
All that is a part of the bigger project ``Holomorphic Floer theory",<br />
joint with Maxim Kontsevich.<br />
<br />
<br />
===Alicia Dickenstein (Buenos Aires)===<br />
<br />
Title: Algebra and geometry in the study of enzymatic cascades<br />
<br />
Abstract: In recent years, techniques from computational and real algebraic geometry have been successfully used to address mathematical challenges in systems biology. The algebraic theory of chemical reaction systems aims to understand their dynamic behavior by taking advantage of the inherent algebraic structure in the kinetic equations, and does not need the determination of the parameters a priori, which can be theoretically or practically impossible.<br />
I will give a gentle introduction to general results based on the network structure. In particular, I will describe a general framework for biological systems, called MESSI systems, that describe Modifications of type Enzyme-Substrate or Swap with Intermediates, and include many networks that model post-translational modifications of proteins inside the cell. I will also outline recent methods to address the important question of multistationarity, in particular in the study of enzymatic cascades, and will point out some of the mathematical challenges that arise from this application.<br />
<br />
<br />
=== Jianfeng Lu (Duke) ===<br />
Title: How to ``localize" the computation?<br />
<br />
It is often desirable to restrict the numerical computation to a local region to achieve best balance between accuracy and affordability in scientific computing. It is important to avoid artifacts and guarantee predictable modelling while artificial boundary conditions have to be introduced to restrict the computation. In this talk, we will discuss some recent understanding on how to achieve such local computation in the context of topological edge states and elliptic random media.<br />
<br />
<br />
===Eugenia Cheng (School of the Art Institute of Chicago)===<br />
<br />
Title: Character vs gender in mathematics and beyond<br />
<br />
Abstract: This presentation will be based on my experience of being a female mathematician, and teaching mathematics at all levels from elementary school to grad school. The question of why women are under-represented in mathematics is complex and there are no simple answers, only many many contributing factors. I will focus on character traits, and argue that if we focus on this rather than gender we can have a more productive and less divisive conversation. To try and focus on characters rather than genders I will introduce gender-neutral character adjectives "ingressive" and "congressive" to replace masculine and feminine. I will share my experience of teaching congressive abstract mathematics to art students, in a congressive way, and the possible effects this could have for everyone in mathematics, not just women.<br />
<br />
<br />
===Omer Mermelstein (Madison)===<br />
<br />
Title: Generic flat pregeometries<br />
<br />
Abstract: In model theory, the tamest of structures are the strongly minimal ones -- those in which every equation in a single variable has either finitely many or cofinitely many solution. Algebraically closed fields and vector spaces are the canonical examples. Zilber’s conjecture, later refuted by Hrushovski, states that the source of geometric complexity in a strongly minimal structure must be algebraic. The property of "flatness" (strict gammoid) of a geometry (matroid) is that which guarantees Hrushovski's construction is devoid of any associative structure.<br />
The majority of the talk will explain what flatness is, how it should be thought of, and how closely it relates to hypergraphs and Hrushovski's construction method. Model theory makes an appearance only in the second part, where I will share results pertaining to the specific family of geometries arising from Hrushovski's methods.<br />
<br />
<br />
===Shamgar Gurevich (Madison)===<br />
<br />
Title: Harmonic Analysis on GL(n) over Finite Fields.<br />
<br />
Abstract: There are many formulas that express interesting properties of a finite group G in terms of sums over its characters. For evaluating or estimating these sums, one of the most salient quantities to understand is the character ratio:<br />
<br />
trace(ρ(g)) / dim(ρ),<br />
<br />
for an irreducible representation ρ of G and an element g of G. For example, Diaconis and Shahshahani stated a formula of the mentioned type for analyzing certain random walks on G.<br />
<br />
Recently, we discovered that for classical groups G over finite fields there is a natural invariant of representations that provides strong information on the character ratio. We call this invariant rank. <br />
<br />
This talk will discuss the notion of rank for the group GLn over finite fields, demonstrate how it controls the character ratio, and explain how one can apply the results to verify mixing time and rate for certain random walks.<br />
<br />
This is joint work with Roger Howe (Yale and Texas AM). The numerics for this work was carried by Steve Goldstein (Madison)<br />
<br />
<br />
===Jose Rodriguez (UW-Madison)===<br />
<br />
Abstract: Determining the closest point to a model (subset of Euclidean space) is an important problem in many applications in science,<br />
engineering, and statistics. One way to solve this problem is by minimizing the squared Euclidean distance function using a gradient<br />
descent approach. However, when there are multiple local minima, there is no guarantee of convergence to the true global minimizer.<br />
An alternative method is to determine the critical points of an objective function on the model.<br />
In algebraic statistics, the models of interest are algebraic sets, i.e., solution sets to a system of multivariate polynomial equations. In this situation, the number of critical points of the squared Euclidean distance function on the model’s Zariski closure is a topological invariant called the Euclidean distance degree (ED degree).<br />
In this talk, I will present some models from computer vision and statistics that may be described as algebraic sets. Moreover,<br />
I will describe a topological method for determining a Euclidean distance degree and a numerical algebraic geometry approach for<br />
determining critical points of the squared Euclidean distance function.<br />
<br />
<br />
===Ananth Shankar (MIT)===<br />
<br />
Abstract: An abelian surface 'splits' if it admits a non-trivial map to some elliptic curve. It is well known that the set of abelian surfaces that split are sparse in the set of all abelian surfaces. Nevertheless, we prove that there are infinitely many split abelian surfaces in arithmetic one-parameter families of generically non-split abelian surfaces. I will describe this work, and if time permits, mention generalizations of this result to the setting of K3 surfaces, as well as applications to the dynamics of hecke orbits. This is joint work with Tang, Maulik-Tang, and Shankar-Tang-Tayou.<br />
<br />
<br />
===Franca Hoffman (Caltech)===<br />
<br />
Title: Gradient Flows: From PDE to Data Analysis.<br />
<br />
Abstract: Certain diffusive PDEs can be viewed as infinite-dimensional gradient flows. This fact has led to the development of new tools in various areas of mathematics ranging from PDE theory to data science. In this talk, we focus on two different directions: model-driven approaches and data-driven approaches.<br />
In the first part of the talk we use gradient flows for analyzing non-linear and non-local aggregation-diffusion equations when the corresponding energy functionals are not necessarily convex. Moreover, the gradient flow structure enables us to make connections to well-known functional inequalities, revealing possible links between the optimizers of these inequalities and the equilibria of certain aggregation-diffusion PDEs.<br />
In the second part, we use and develop gradient flow theory to design novel tools for data analysis. We draw a connection between gradient flows and Ensemble Kalman methods for parameter estimation. We introduce the Ensemble Kalman Sampler - a derivative-free methodology for model calibration and uncertainty quantification in expensive black-box models. The interacting particle dynamics underlying our algorithm can be approximated by a novel gradient flow structure in a modified Wasserstein metric which reflects particle correlations. The geometry of this modified Wasserstein metric is of independent theoretical interest.<br />
<br />
<br />
=== Jeffrey Danciger (UT Austin) ===<br />
<br />
Title: Affine geometry and the Auslander Conjecture<br />
<br />
Abstract: The Auslander Conjecture is an analogue of Bieberbach’s theory of Euclidean crystallographic groups in the setting of affine geometry. It predicts that a complete affine manifold (a manifold equipped with a complete torsion-free flat affine connection) which is compact must have virtually solvable fundamental group. The conjecture is known up to dimension six, but is known to fail if the compactness assumption is removed, even in low dimensions. We discuss some history of this conjecture, give some basic examples, and then survey some recent advances in the study of non-compact complete affine manifolds with non-solvable fundamental group. <br />
Tools from the deformation theory of pseudo-Riemannian hyperbolic manifolds and also from higher Teichm&uuml;ller theory will enter the picture.<br />
<br />
<br />
=== Tatyana Shcherbina (Princeton) ===<br />
<br />
Title: Random matrix theory and supersymmetry techniques<br />
<br />
Abstract: Starting from the works of Erdos, Yau, Schlein with coauthors, the significant progress in understanding the universal behavior of many random graph and random matrix models were achieved. However for the random matrices with a special structure our understanding is still very limited. In this talk I am going to overview applications of another approach to the study of the local eigenvalues statistics in random matrix theory based on so-called supersymmetry techniques (SUSY). SUSY approach is based on the representation of the determinant as an integral over the Grassmann (anticommuting) variables. Combining this representation with the representation of an inverse determinant as an integral over the Gaussian complex field, SUSY allows to obtain an integral representation for the main spectral characteristics of random matrices such as limiting density, correlation functions, the resolvent's elements, etc. This method is widely (and successfully) used in the physics literature and is potentially very powerful but the rigorous control of the integral representations, which can be obtained by this method, is quite difficult, and it requires powerful analytic and statistical mechanics tools. In this talk we will discuss some recent progress in application of SUSY to the analysis of local spectral characteristics of the prominent ensemble of random band matrices, i.e. random matrices<br />
whose entries become negligible if their distance from the main diagonal exceeds a certain parameter called the band width. <br />
<br />
<br />
=== Tingran Gao (University of Chicago) ===<br />
<br />
Title: Manifold Learning on Fibre Bundles<br />
<br />
Abstract: Spectral geometry has played an important role in modern geometric data analysis, where the technique is widely known as Laplacian eigenmaps or diffusion maps. In this talk, we present a geometric framework that studies graph representations of complex datasets, where each edge of the graph is equipped with a non-scalar transformation or correspondence. This new framework models such a dataset as a fibre bundle with a connection, and interprets the collection of pairwise functional relations as defining a horizontal diffusion process on the bundle driven by its projection on the base. The eigenstates of this horizontal diffusion process encode the “consistency” among objects in the dataset, and provide a lens through which the geometry of the dataset can be revealed. We demonstrate an application of this geometric framework on evolutionary anthropology.<br />
<br />
<br />
=== Andrew Zimmer (LSU) ===<br />
<br />
Title: Intrinsic and extrinsic geometries in several complex variables<br />
<br />
Abstract: A bounded domain in complex Euclidean space, despite being one of the simplest types of manifolds, has a number of interesting geometric structures. When the domain is pseudoconvex, it has a natural intrinsic geometry: the complete Kaehler-Einstein metric constructed by Cheng-Yau and Mok-Yau. When the domain is smoothly bounded, there is also a natural extrinsic structure: the CR-geometry of the boundary. In this talk, I will describe connections between these intrinsic and extrinsic geometries. Then, I will discuss how these connections can lead to new analytic results.<br />
<br />
=== Charlotte Chan (MIT) ===<br />
<br />
Title: Flag varieties and representations of p-adic groups<br />
<br />
Abstract: In the 1950s, Borel, Weil, and Bott showed that the<br />
irreducible representations of a complex reductive group can be<br />
realized in the cohomology of line bundles on flag varieties. In the<br />
1970s, Deligne and Lusztig constructed a family of subvarieties of<br />
flag varieties whose cohomology realizes the irreducible<br />
representations of reductive groups over finite fields. I will survey<br />
these stories, explain recent progress towards finding geometric<br />
constructions of representations of p-adic groups, and discuss<br />
interactions with the Langlands program.<br />
<br />
=== Hui Yu (Columbia) ===<br />
<br />
Title: Singular sets in obstacle problems<br />
<br />
Abstract: One of the most important free boundary problems is the obstacle problem. The regularity of its free boundary has been studied for over half a century. In this talk, we review some classical results as well as exciting new developments. In particular, we discuss the recent resolution of the regularity of the singular set for the fully nonlinear obstacle problem. This talk is based on a joint work with Ovidiu Savin at Columbia University.<br />
<br />
=== Alex Waldron (Michigan) ===<br />
<br />
Title: Gauge theory and geometric flows<br />
<br />
Abstract: I will give a brief introduction to two major areas of research in differential geometry: gauge theory and geometric flows. I'll then introduce a geometric flow (Yang-Mills flow) arising from a variational problem with origins in physics, which has been studied by geometric analysts since the early 1980s. I'll conclude by discussing my own work on the behavior of Yang-Mills flow in the critical dimension (n = 4).<br />
<br />
=== Nick Higham (Manchester) ===<br />
<br />
Title: Challenges in Multivalued Matrix Functions<br />
<br />
Abstract: In this lecture I will discuss multivalued matrix functions that arise in solving various kinds of matrix equations. The matrix logarithm is the prototypical example, and my first interaction with Hans Schneider was about this function. Another example is the Lambert W function of a matrix, which is much less well known but has been attracting recent interest. A theme of the talk is the importance of choosing appropriate principal values and making sure that the correct choices of signs and branches are used,<br />
both in theory and in computation. I will give examples where incorrect results have previously been obtained.<br />
<br />
I focus on matrix inverse trigonometric and inverse hyperbolic functions, beginning by investigating existence and characterization. Turning to the principal values, various functional identities are derived, some of which are new even in the scalar case, including a “round trip” formula that relates acos(cos A) to A and similar formulas for the other inverse functions. Key tools used in the derivations are the matrix unwinding function and the matrix sign function.<br />
<br />
A new inverse scaling and squaring type algorithm employing a Schur decomposition and variable-degree Pade approximation is derived for computing acos, and it is shown how it can also be used to compute asin, acosh, and asinh.<br />
<br />
=== Chenxi Wu (Rutgers) ===<br />
<br />
Title: Kazhdan's theorem on metric graphs<br />
<br />
Abstract: I will give an introduction to the concept of canonical (arakelov) metric on a metric graph, which is related to combinatorial questions like the counting of spanning trees, and generalizes the corresponding concept on Riemann surfaces. I will also present a recent result in collaboration with Farbod Shokrieh on the convergence of canonical metric under normal covers.<br />
<br />
=== Ruobing Zhang (Stony Brook) ===<br />
<br />
Title: Geometry and analysis of degenerating Calabi-Yau manifolds<br />
<br />
Abstract: This talk concerns a naturally occurring family of degenerating Calabi-Yau manifolds. A primary tool in analyzing their behavior is to combine the recently developed structure theory for Einstein manifolds and multi-scale singularity analysis for degenerating nonlinear PDEs in the collapsed setting. Based on the algebraic degeneration, we will give precise and more quantitative descriptions of singularity formation from both metric and analytic points of view.<br />
<br />
=== Thomas Lam (Michigan) === <br />
<br />
Title: Positive geometries and string theory amplitudes<br />
<br />
Abstract: Inspired by developments in quantum field theory, we<br />
recently defined the notion of a positive geometry, a class of spaces<br />
that includes convex polytopes, positive parts of projective toric<br />
varieties, and positive parts of flag varieties. I will discuss some<br />
basic features of the theory and an application to genus zero string<br />
theory amplitudes. As a special case, we obtain the Euler beta<br />
function, familiar to mathematicians, as the "stringy canonical form"<br />
of the closed interval.<br />
<br />
This talk is based on joint work with Arkani-Hamed, Bai, and He.<br />
<br />
=== Peter Cholak (Notre Dame) ===<br />
<br />
Title: What can we compute from solutions to combinatorial problems?<br />
<br />
Abstract: This will be an introductory talk to an exciting current <br />
research area in mathematical logic. Mostly we are interested in <br />
solutions to Ramsey's Theorem. Ramsey's Theorem says for colorings <br />
C of pairs of natural numbers, there is an infinite set H such that <br />
all pairs from H have the same constant color. H is called a homogeneous <br />
set for C. What can we compute from H? If you are not sure, come to <br />
the talk and find out!<br />
<br />
=== Saulo Orizaga (Duke) ===<br />
<br />
Title: Introduction to phase field models and their efficient numerical implementation<br />
<br />
Abstract: In this talk we will provide an introduction to phase field models. We will focus in models<br />
related to the Cahn-Hilliard (CH) type of partial differential equation (PDE). We will discuss the<br />
challenges associated in solving such higher order parabolic problems. We will present several<br />
new numerical methods that are fast and efficient for solving CH or CH-extended type of problems.<br />
The new methods and their energy-stability properties will be discussed and tested with several computational examples commonly found in material science problems. If time allows, we will talk about more applications in which phase field models are useful and applicable.<br />
<br />
=== Caglar Uyanik (Yale) ===<br />
<br />
Title: Hausdorff dimension and gap distribution in billiards<br />
<br />
Abstract: A classical “unfolding” procedure allows one to turn questions about billiard trajectories in a Euclidean polygon into questions about the geodesic flow on a surface equipped with a certain geometric structure. Surprisingly, the flow on the surface is in turn related to the geodesic flow on the classical moduli spaces of Riemann surfaces. Building on recent breakthrough results of Eskin-Mirzakhani-Mohammadi, we prove a large deviations result for Birkhoff averages as well as generalize a classical theorem of Masur on geodesics in the moduli spaces of translation surfaces. <br />
<br />
=== Andy Zucker (Lyon) ===<br />
<br />
Title: Topological dynamics of countable groups and structures<br />
<br />
Abstract: We give an introduction to the abstract topological dynamics <br />
of topological groups, i.e. the study of the continuous actions of a <br />
topological group on a compact space. We are particularly interested <br />
in the minimal actions, those for which every orbit is dense. <br />
The study of minimal actions is aided by a classical theorem of Ellis, <br />
who proved that for any topological group G, there exists a universal <br />
minimal flow (UMF), a minimal G-action which factors onto every other <br />
minimal G-action. Here, we will focus on two classes of groups: <br />
a countable discrete group and the automorphism group of a countable <br />
first-order structure. In the case of a countable discrete group, <br />
Baire category methods can be used to show that the collection of <br />
minimal flows is quite rich and that the UMF is rather complicated. <br />
For an automorphism group G of a countable structure, combinatorial <br />
methods can be used to show that sometimes, the UMF is trivial, or <br />
equivalently that every continuous action of G on a compact space <br />
admits a global fixed point.<br />
<br />
=== Lillian Pierce (Duke) ===<br />
<br />
Title: On Bourgain’s counterexample for the Schrödinger maximal function<br />
<br />
Abstract: In 1980, Carleson asked a question in harmonic analysis: to which Sobolev space $H^s$ must an initial data function belong, for a pointwise a.e. convergence result to hold for the solution to the associated linear Schrödinger equation? Over the next decades, many people developed counterexamples to push the (necessary) range of s up, and positive results to push the (sufficient) range of s down. Now, these ranges are finally meeting: Bourgain’s 2016 counterexample showed s < n/(2(n+1)) fails, and Du and Zhang’s 2019 paper shows that s>n/(2(n+1)) suffices. <br />
In this talk, we will give an overview of how to rigorously derive Bourgain’s 2016 counterexample, based on simple facts from number theory. We will show how to build Bourgain’s counterexample starting from “zero knowledge," and how to gradually optimize the set-up to arrive at the final counterexample. The talk will be broadly accessible, particularly if we live up to the claim of starting from “zero knowledge.”<br />
<br />
=== Joe Kileel (Princeton) ===<br />
<br />
Title: Inverse Problems, Imaging and Tensor Decomposition<br />
<br />
Abstract: Perspectives from computational algebra and optimization are brought <br />
to bear on a scientific application and a data science application. <br />
In the first part of the talk, I will discuss cryo-electron microscopy <br />
(cryo-EM), an imaging technique to determine the 3-D shape of <br />
macromolecules from many noisy 2-D projections, recognized by the 2017 <br />
Chemistry Nobel Prize. Mathematically, cryo-EM presents a <br />
particularly rich inverse problem, with unknown orientations, extreme <br />
noise, big data and conformational heterogeneity. In particular, this <br />
motivates a general framework for statistical estimation under compact <br />
group actions, connecting information theory and group invariant <br />
theory. In the second part of the talk, I will discuss tensor rank <br />
decomposition, a higher-order variant of PCA broadly applicable in <br />
data science. A fast algorithm is introduced and analyzed, combining <br />
ideas of Sylvester and the power method.<br />
<br />
=== Cynthia Vinzant (NCSU) ===<br />
<br />
Title: Matroids, log-concavity, and expanders<br />
<br />
Abstract: Matroids are combinatorial objects that model various types of independence. They appear several fields mathematics, including graph theory, combinatorial optimization, and algebraic geometry. In this talk, I will introduce the theory of matroids along with the closely related class of polynomials called strongly log-concave polynomials. Strong log-concavity is a functional property of a real multivariate polynomial that translates to useful conditions on its coefficients. Discrete probability distributions defined by these coefficients inherit several of these nice properties. I will discuss the beautiful real and combinatorial geometry underlying these polynomials and describe applications to random walks on the faces of simplicial complexes. Consequences include proofs of Mason's conjecture that the sequence of numbers of independent sets of a matroid is ultra log-concave and the Mihail-Vazirani conjecture that the basis exchange graph of a matroid has expansion at least one. This is based on joint work with Nima Anari, Kuikui Liu, and Shayan Oveis Gharan.<br />
<br />
== Future Colloquia ==<br />
[[Colloquia/Fall 2020| Fall 2020]]<br />
<br />
== Past Colloquia ==<br />
<br />
[[Colloquia/Blank|Blank]]<br />
<br />
[[Colloquia/Spring2019|Spring 2019]]<br />
<br />
[[Colloquia/Fall2018|Fall 2018]]<br />
<br />
[[Colloquia/Spring2018|Spring 2018]]<br />
<br />
[[Colloquia/Fall2017|Fall 2017]]<br />
<br />
[[Colloquia/Spring2017|Spring 2017]]<br />
<br />
[[Archived Fall 2016 Colloquia|Fall 2016]]<br />
<br />
[[Colloquia/Spring2016|Spring 2016]]<br />
<br />
[[Colloquia/Fall2015|Fall 2015]]<br />
<br />
[[Colloquia/Spring2014|Spring 2015]]<br />
<br />
[[Colloquia/Fall2014|Fall 2014]]<br />
<br />
[[Colloquia/Spring2014|Spring 2014]]<br />
<br />
[[Colloquia/Fall2013|Fall 2013]]<br />
<br />
[[Colloquia 2012-2013|Spring 2013]]<br />
<br />
[[Colloquia 2012-2013#Fall 2012|Fall 2012]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS/Spring2020&diff=18486Applied/ACMS/Spring20202019-11-24T04:00:22Z<p>Spagnolie: /* Spring 2020 */</p>
<hr />
<div>== Spring 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
| Jan 31<br />
|[https://www.math.wisc.edu/~hung/ Hung Tran] (UW-Madison)<br />
|''[[Applied/ACMS/absS20#Hung Tran (UW-Madison)| Coagulation-Fragmentation equations with multiplicative coagulation kernel and constant fragmentation kernel]]''<br />
| Li<br />
|-<br />
| Feb 7<br />
|[https://www.usna.edu/Users/weaprcon/avramov/index.php Svetlana Avramov-Zamurovic] (United States Naval Academy)<br />
|''[[Applied/ACMS/absS20#Svetlana Avramov-Zamurovic (United States Naval Academy)|TBA]]''<br />
| Stechmann<br />
|-<br />
| Feb 14<br />
|[http://math.mit.edu/~vadicgor/ Gorin Vadim] (UW-Madison)<br />
|''[[Applied/ACMS/absS20#Gorin Vadim (UW-Madison)|TBA, either random matrix or KPZ equation]]''<br />
| Li<br />
|-<br />
| Feb 21<br />
|[website] (institution)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|title]]''<br />
| host<br />
|-<br />
| Feb 28<br />
|[https://cims.nyu.edu/~yangq/ Qiu Yang] (NYU/UVic/NCAR)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|title]]''<br />
| Chen<br />
|-<br />
| Mar 6<br />
|[website] (institution)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|title]]''<br />
| host<br />
|-<br />
| Mar 13<br />
|[http://www.columbia.edu/~ktm2132/ Kyle Mandli] (Columbia)<br />
|''[[Applied/ACMS/absS20#Kyle Mandli (Columbia)|TBA]]''<br />
| Wally<br />
|-<br />
| Mar 20<br />
|[Spring break] (Spring Break!)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|title]]''<br />
| host<br />
|-<br />
| Mar 27<br />
|[http://www-personal.umich.edu/~jcsch/ John Schotland] (U Mich)<br />
|''[[Applied/ACMS/absS20#John Schotland (Michigan)|title]]''<br />
| host<br />
|-<br />
| Apr 3<br />
|[http://keaton-burns.com/ Keaton Burns] (MIT)<br />
|''[[Applied/ACMS/absS20#Keaton Burns (MIT)|title]]''<br />
| Spagnolie<br />
|-<br />
| Apr 10<br />
|[https://www.princeton.edu/~lecoanet/ Daniel Lecoanet] (Princeton)<br />
|''[[Applied/ACMS/absS20#Daniel Lecoanet (Princeton)|TBA]]''<br />
| Wally<br />
|-<br />
| Apr 17<br />
|[https://www.ornl.gov/staff-profile/hoang-tran Hoang Tran] (Oak Ridge National Laboratory)<br />
|''[[Applied/ACMS/absS20#Hoang Tran (institution)|title]]''<br />
| Tran<br />
|-<br />
| Apr 24<br />
|[https://www.pml.unc.edu/ Pedro Saenz] (UNC)<br />
|''[[Applied/ACMS/absF19#Pedro Saenz (UNC)|TBA]]''<br />
| Spagnolie</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS/Spring2020&diff=18485Applied/ACMS/Spring20202019-11-24T03:59:20Z<p>Spagnolie: </p>
<hr />
<div>== Spring 2020 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
| Jan 31<br />
|[https://www.math.wisc.edu/~hung/ Hung Tran] (UW-Madison)<br />
|''[[Applied/ACMS/absS20#Hung Tran (UW-Madison)| Coagulation-Fragmentation equations with multiplicative coagulation kernel and constant fragmentation kernel]]''<br />
| Li<br />
|-<br />
| Feb 7<br />
|[https://www.usna.edu/Users/weaprcon/avramov/index.php Svetlana Avramov-Zamurovic] (United States Naval Academy)<br />
|''[[Applied/ACMS/absS20#Svetlana Avramov-Zamurovic (United States Naval Academy)|TBA]]''<br />
| Stechmann<br />
|-<br />
| Feb 14<br />
|[http://math.mit.edu/~vadicgor/ Gorin Vadim] (UW-Madison)<br />
|''[[Applied/ACMS/absS20#Gorin Vadim (UW-Madison)|TBA, either random matrix or KPZ equation]]''<br />
| Li<br />
|-<br />
| Feb 21<br />
|[website] (institution)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|title]]''<br />
| host<br />
|-<br />
| Feb 28<br />
|[https://cims.nyu.edu/~yangq/ Qiu Yang] (NYU/UVic/NCAR)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|title]]''<br />
| Chen<br />
|-<br />
| Mar 6<br />
|[website] (institution)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|title]]''<br />
| host<br />
|-<br />
| Mar 13<br />
|[http://www.columbia.edu/~ktm2132/ Kyle Mandli] (Columbia)<br />
|''[[Applied/ACMS/absS20#Kyle Mandli (Columbia)|TBA]]''<br />
| Wally<br />
|-<br />
| Mar 20<br />
|[Spring break] (Spring Break!)<br />
|''[[Applied/ACMS/absS20#Speaker (institution)|title]]''<br />
| host<br />
|-<br />
| Mar 27<br />
|[http://www-personal.umich.edu/~jcsch/ John Schotland] (U Mich)<br />
|''[[Applied/ACMS/absS20#John Schotland (Michigan)|title]]''<br />
| host<br />
|-<br />
| Apr 3<br />
|[website] (institution)<br />
|''[[Applied/ACMS/absS20#Keaton Burns (MIT)|title]]''<br />
| Spagnolie<br />
|-<br />
| Apr 10<br />
|[https://www.princeton.edu/~lecoanet/ Daniel Lecoanet] (Princeton)<br />
|''[[Applied/ACMS/absS20#Daniel Lecoanet (Princeton)|TBA]]''<br />
| Wally<br />
|-<br />
| Apr 17<br />
|[https://www.ornl.gov/staff-profile/hoang-tran Hoang Tran] (Oak Ridge National Laboratory)<br />
|''[[Applied/ACMS/absS20#Hoang Tran (institution)|title]]''<br />
| Tran<br />
|-<br />
| Apr 24<br />
|[https://www.pml.unc.edu/ Pedro Saenz] (UNC)<br />
|''[[Applied/ACMS/absF19#Pedro Saenz (UNC)|TBA]]''<br />
| Spagnolie</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS/absF19&diff=18363Applied/ACMS/absF192019-11-08T15:48:18Z<p>Spagnolie: /* ACMS Abstracts: Fall 2019 */</p>
<hr />
<div>= ACMS Abstracts: Fall 2019 =<br />
<br />
=== Leonardo Andrés Zepeda Núñez ===<br />
<br />
Title: Deep Learning for Electronic Structure Computations: A Tale of Symmetries, Locality, and Physics<br />
<br />
Abstract: Recently, the surge of interest in deep neural learning has dramatically improved image and signal processing, which has fueled breakthroughs in many domains such as drug discovery, genomics, and automatic translation. These advances have been further applied to scientific computing and, in particular, to electronic structure computations. In this case, the main objective is to directly compute the electron density, which encodes most of information of the system, thus bypassing the computationally intensive solution of the Kohn-Sham equations. However, similar to neural networks for image processing, the performance of the methods depends spectacularly on the physical and analytical intuition incorporated in the network, and on the training stage.<br />
<br />
In this talk, I will show how to build a network that respects physical symmetries and locality. I will show how to train the networks and how such properties impact the performance of the resulting network. Finally, I will present several examples for small yet realistic chemical systems.<br />
<br />
<br />
=== Daniel Floryan (UW-Madison) ===<br />
<br />
Title: Flexible Inertial Swimmers<br />
<br />
Abstract: Inertial swimmers deform their bodies and fins to push against the water and propel themselves forward. The deformation is driven partly by active musculature, and partly by passive elasticity. The interaction between elasticity and hydrodynamics confers features on the swimmers not enjoyed by their rigid friends, for example, boosts in speed when flapping at certain frequencies. We explain the salient features of flexible swimmers by drawing ideas from airfoils, vibrating beams, and flags flapping in the wind. The presence of fluid drag has important consequences. We also explore optimal arrangements of flexibility. (It turns out that nature is quite good.)<br />
<br />
<br />
=== Jianfeng Lu (Duke) ===<br />
<br />
Title: How to ``localize" the computation?<br />
<br />
It is often desirable to restrict the numerical computation to a local <br />
region to achieve best balance between accuracy and affordability in scientific computing. It is important to avoid artifacts and guarantee predictable modelling while artificial boundary conditions have to be introduced to restrict the computation. In this talk, we will discuss some recent understanding on how to achieve such local computation in the context of topological edge states and elliptic random media.<br />
<br />
<br />
=== Mitch Bushuk (GFDL/Princeton) ===<br />
<br />
Title: Arctic Sea Ice Predictability in a Changing Cryosphere<br />
<br />
Abstract: Forty years of satellite observations have documented a striking decline in the areal extent of Arctic sea ice. The loss of sea ice has impacts on the climate system, human populations, ecosystems, and natural environments across a broad range of spatial and temporal scales. These changes have motivated significant research interest in the predictability and prediction of Arctic sea ice on seasonal-to-interannual timescales. In this talk, I will address two related questions: (1) What is the inherent predictability of Arctic sea ice and what physical mechanisms underlie this predictability? and (2) How can this knowledge be leveraged to improve operational sea ice predictions? I will present findings on the relative roles of the ocean, sea ice, and atmosphere in controlling Arctic sea ice predictability. I will also present evidence for an Arctic spring predictability barrier, which may impose a sharp limit on our ability to make skillful predictions of the summer sea ice minimum. <br />
<br />
<br />
=== Qin Li (UW-Madison) ===<br />
<br />
Title: The power of randomness in scientific computing<br />
<br />
Abstract: Most numerical methods in scientific computing are deterministic. Traditionally, accuracy has been the target while the cost was not the concern. However, in this era of big data, we incline to relax the strict requirements on the accuracy to reduce numerical cost. Introducing randomness in the numerical solvers could potentially speed up the computation significantly at small sacrifice of accuracy. In this talk, I'd like to show two concrete examples how this is done: first on random sketching in experimental design, and the second on numerical homgenization, hoping the discussion can shed light on potential other applications. Joint work with Ke Chen, Jianfeng Lu, Kit Newton and Stephen Wright.<br />
<br />
<br />
=== Joel Nishimura (Arizona State) ===<br />
<br />
Title: Random graph models with fixed degree sequences: choices, consequences and irreducibility proofs for sampling<br />
<br />
Abstract: Determining which features of an empirical graph are noteworthy frequently relies upon the ability to sample random graphs with constrained properties. Since empirical graphs have distinctive degree sequences, one of the most popular random graph models is the configuration model, which produces a graph uniformly at random from the set of graphs with a fixed degree sequence. While it is commonly treated as though there is only a single configuration model, one sampled via stub-matching, there are many, depending on whether self-loops and multiedges are allowed and whether edge stubs are labeled or not. We show, these different configuration models can lead to drastically, sometimes opposite, interpretations of empirical graphs. In order to sample from these different configuration models, we review and develop the underpinnings of Markov chain Monte Carlo methods based upon double-edge swaps. We also present new results on the irreducibility of the Markov chain for graphs with self-loops, either proving irreducibility or exactly characterizing the degree sequences for which the Markov chain is reducible. This work completes the study of the irreducibility of double edge-swap Markov chains (and the related Curveball Markov chain) for all combinations of allowing self-loops, multiple self-loops and/or multiedges. <br />
<br />
<br />
=== Alex Townsend (Cornell) ===<br />
<br />
Title: Why are so many matrices and tensors of low rank in computational mathematics?<br />
<br />
Abstract: Matrices and tensors that appear in computational mathematics are so often well-approximated by low-rank objects. Since random ("average") matrices are almost surely of full rank, mathematics needs to explain the abundance of low-rank structures. We will give various methodologies that allow one to begin to understand the prevalence of compressible matrices and tensors and we hope to reveal an underlying link between disparate applications. In particular, we will show how one can connect the singular values of a matrix with displacement structure to a rational approximation problem that highlights fundamental connections between polynomial interpolation, Krylov methods, and fast Toeplitz solvers.<br />
<br />
<br />
=== Prashant G. Mehta ===<br />
<br />
Title: What is the Lagrangian for Nonlinear Filtering?<br />
<br />
Abstract: There is a certain magic involved in recasting the equations in Physics, and the algorithms in Engineering, in variational terms. The most classical of these ‘magics’ is the Lagrange’s formulation of the Newtonian mechanics. An accessible modern take on all this and more appears in the February 19, 2019 issue of The New Yorker magazine: https://www.newyorker.com/science/elements/a-different-kind-of-theory-of-everything?reload=true <br />
<br />
My talk is concerned with a variational (optimal control type) formulation of the problem of nonlinear filtering/estimation. Such formulations are referred to as duality between optimal estimation and optimal control. The first duality principle appears in the seminal (1961) paper of Kalman-Bucy, where the problem of minimum variance estimation is shown to be dual to a linear quadratic optimal control problem. <br />
<br />
In my talk, I will describe a generalization of the Kalman-Bucy duality theory to nonlinear filtering. The generalization is an exact extension, in the sense that the dual optimal control problem has the same minimum variance structure for linear and nonlinear filtering problems. Kalman-Bucy’s classical result is shown to be a special case. During the talk, I will also attempt to review other types of duality relationships that have appeared over the years for the problem of linear and nonlinear filtering. <br />
<br />
This is joint work with Jin Won Kim and Sean Meyn. The talk is based on the following papers: https://arxiv.org/pdf/1903.11195.pdf and https://arxiv.org/pdf/1904.01710.pdf.<br />
<br />
<br />
=== Jean-Luc Thiffeault ===<br />
<br />
Title: Shape matters: A Brownian swimmer in a channel<br />
<br />
Abstract: We consider a simple model of a two-dimensional microswimmer with fixed swimming speed. The direction of swimming changes according to<br />
a Brownian process, and the swimmer is interacting with boundaries. This is a standard model for a simple microswimmer, or a confined<br />
wormlike chain polymer. The shape of the swimmer determines the range of allowable values that its degrees of freedom can assume --- its<br />
configuration space. Using natural assumptions about reflection of the swimmer at boundaries, we compute the swimmer's invariant<br />
distribution across a channel consisting of two parallel walls, and the statistics of spreading in the longitudinal direction. This gives<br />
us the effective diffusion constant of the swimmer's large scale motion. When the swimmer is longer than the channel width, it cannot<br />
reverse, and we then compute the mean drift velocity of the swimmer. This model offers insight into experiments of scattering of swimmers<br />
from boundaries, and serves as an exactly-solvable baseline when comparing to more complex models. This is joint work with Hongfei Chen.<br />
<br />
=== Tan Bui (UT-Austin) ===<br />
<br />
Title: Scalable Algorithms for Data-driven Inverse and Learning Problems<br />
<br />
Abstract: Inverse problems and uncertainty quantification (UQ) are pervasive in scientific discovery and decision-making for complex, natural, engineered, and societal systems. They are perhaps the most popular mathematical approaches for enabling predictive scientific simulations that integrate observational/experimental data, simulations and/or models. Unfortunately, inverse/UQ problems for practical complex systems possess these the simultaneous challenges: the large-scale forward problem challenge, the high dimensional parameter space challenge, and the big data challenge.<br />
<br />
To address the first challenge, we have developed parallel high-order (hybridized) discontinuous Galerkin methods to discretize complex forward PDEs. <br />
To address the second challenge, we have developed various approaches from model reduction to advanced Markov chain Monte Carlo methods to effectively explore high dimensional parameter spaces to compute posterior statistics. To address the last challenge, we have developed a randomized misfit approach that uncovers the interplay between the Johnson-Lindenstrauss and the Morozov's discrepancy principle to significantly reduce the dimension of the data without compromising the quality of the inverse solutions.<br />
<br />
In this talk we selectively present scalable and rigorous approaches to tackle these challenges for PDE-governed Bayesian inverse problems. Various numerical results for simple to complex PDEs will be presented to verify our algorithms and theoretical findings. If time permits, we will present our recent work on scientific machine learning for inverse and learning problems.<br />
<br />
=== Wenxiao Pan (UW-Madison) ===<br />
<br />
Title: Mesoscale Modeling of Soft Matter<br />
<br />
Abstract: Soft matter systems, such as colloids and polymers, are characterized by an interplay of interactions and processes that span a wide range of length- and time scales. Computer simulations require modeling approaches to cover these scales. In order to access mesoscopic time- and length scales, necessary to access material properties, two numerical approaches will be discussed in this talk. The first one concerns suspension flows of arbitrary-shaped colloids. A high-order, spatially adaptive, meshless method was developed to solve the PDEs that govern hydrodynamics and fluid- solid interactions. Near-field hydrodynamic interactions between arbitrary-shaped colloids can be accurately captured without subgrid-scale lubrication models. The second approach seeks a bottom-up, coarse-grained modeling for polymers in solution. It starts from atomistic descriptions, and by proper mapping atomistic details onto a coarser representation, arrives at the mesoscale. The effect of unresolved degrees of freedom on the kinetics of polymers is accounted by the non-Markovian memory kernel. The coarse-grained variables and governing equation are directly linked to the statistics of atomistic data.<br />
<br />
=== Prerna Gera (UW-Madison) ===<br />
<br />
Title: Patchy Vesicles in Shear Flow<br />
<br />
Abstract: Multicomponent vesicles are fluid filled structure enclosed by a lipid bilayer and are composed of cholesterol that combine with saturated lipids to form energetically stable domains on the vesicle surface. The presence of different lipid species lead to varying material properties, such as bending rigidity, produce a rich variety of dynamics as seen in experiments. In the first part of the talk, a three dimensional continuum model will be presented to explore the dynamics of multicomponent vesicle. The membrane is modeled using a two-phase surface Cahn-Hilliard equation along with a level/set closest point method. The domain on the membrane is coupled with fluid surrounding the vesicle via an energy variation approach. Motivated by the results from the continuum simulations, a small amplitude asymptotic approach is used to derive a reduced order model and predict the low wave numbers breathing and trembling behavior of the membrane.</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS&diff=18362Applied/ACMS2019-11-08T15:46:13Z<p>Spagnolie: /* Fall 2019 */</p>
<hr />
<div>__NOTOC__<br />
<br />
= Applied and Computational Mathematics Seminar =<br />
<br />
*'''When:''' Fridays at 2:25pm (except as otherwise indicated)<br />
*'''Where:''' 901 Van Vleck Hall<br />
*'''Organizers:''' [http://www.math.wisc.edu/~qinli/ Qin Li], [http://www.math.wisc.edu/~spagnolie/ Saverio Spagnolie] and [http://www.math.wisc.edu/~jeanluc Jean-Luc Thiffeault]<br />
*'''To join the ACMS mailing list:''' See [https://admin.lists.wisc.edu/index.php?p=11&l=acms mailing list] website.<br />
<br />
<br><br />
<br />
<br />
== Fall 2019 ==<br />
<br />
{| cellpadding="8"<br />
!align="left" | date<br />
!align="left" | speaker<br />
!align="left" | title<br />
!align="left" | host(s)<br />
|-<br />
| Sept 6<br />
|[http://math.mit.edu/~lzepeda/ Leonardo Andrés Zepeda Núñez] (UW-Madison)<br />
|''[[Applied/ACMS/absF19#Leonardo Andrés Zepeda Núñez (UW-Madison)|Deep Learning for Electronic Structure Computations: A Tale of Symmetries, Locality, and Physics]]''<br />
| Li<br />
|-<br />
| Sept 13<br />
|[http://dfloryan.mycpanel.princeton.edu/ Daniel Floryan] (UW-Madison)<br />
|''[[Applied/ACMS/absF19#Daniel Floryan (UW-Madison)|Flexible Inertial Swimmers]]''<br />
| Jean-Luc<br />
|-<br />
| Sept 14-15<br />
|[https://www.ams.org/meetings/sectional/2267_program.html AMS sectional meeting]<br />
| UW-Madison<br />
|-<br />
| Sept 20<br />
|[https://www.gfdl.noaa.gov/mitch-bushuk/ Mitch Bushuk] (GFDL/Princeton)<br />
|''[[Applied/ACMS/absF19#Mitch Bushuk (GFDL/Princeton)|Arctic Sea Ice Predictability in a Changing Cryosphere]]''<br />
| Chen<br />
|-<br />
| Sept 20 (colloquium, 4pm, B239)<br />
|[https://services.math.duke.edu/~jianfeng/ Jianfeng Lu] (Duke)<br />
|''[[Applied/ACMS/absF19#Jianfeng Lu (Duke)|How to "localize" the computation?]]''<br />
| Li<br />
|-<br />
| Sept 27<br />
|[http://www.math.wisc.edu/~qinli/ Qin Li] (UW-Madison)<br />
|''[[Applied/ACMS/absF19#Qin Li (UW-Madison)|The power of randomness in scientific computing]]''<br />
| host<br />
|-<br />
| Oct 4<br />
|[https://isearch.asu.edu/profile/2169104 Joel Nishimura] (Arizona State)<br />
|''[[Applied/ACMS/absF19#Joel Nishimura (Arizona State)|Random graph models with fixed degree sequences: choices, consequences and irreducibility proofs for sampling]]''<br />
| Cochran<br />
|-<br />
| Oct 11<br />
|[http://pi.math.cornell.edu/~ajt/ Alex Townsend] (Cornell)<br />
|''[[Applied/ACMS/absF19#Alex Townsend (Cornell)|Why are so many matrices and tensors of low rank in computational mathematics?]]''<br />
| Li<br />
|-<br />
| Oct 18<br />
|[http://mehta.mechse.illinois.edu/ Prashant G. Mehta] (UIUC)<br />
|''[[Applied/ACMS/absF19#Prashant G. Mehta (UIUC)|What is the Lagrangian for Nonlinear Filtering?]]''<br />
| Chen<br />
|-<br />
| Oct 25<br />
|[https://www.math.wisc.edu/~jeanluc/ Jean-Luc Thiffeault] (UW-Madison)<br />
|''[[Applied/ACMS/absF19#Jean-Luc Thiffeault|Shape matters: A Brownian microswimmer interacting with walls]]''<br />
| <br />
|-<br />
| Nov 1<br />
|[https://users.oden.utexas.edu/~tanbui/ Tan Bui] (UT-Austin)<br />
|''[[Applied/ACMS/absF19#Tan Bui (UT-Austin)|Scalable Algorithms for Data-driven Inverse and Learning Problems]]''<br />
| Li<br />
|-<br />
| Nov 8<br />
|[https://pan.labs.wisc.edu/staff/pan-wenxiao/ Wenxiao Pan] (UW)<br />
|''[[Applied/ACMS/absF19#Wenxiao Pan (UW)|Mesoscale Modeling of Soft Matter]]''<br />
| Spagnolie<br />
| <br />
|-<br />
| Nov 15<br />
|[https://www.math.wisc.edu/~pgera/ Prerna Gera] (UW)<br />
|''[[Applied/ACMS/absF19#Prerna Gera (UW)|Patchy Vesicles in Shear Flow]]''<br />
| Spagnolie<br />
|-<br />
| Dec 6<br />
|[https://math.berkeley.edu/~linlin/ Lin Lin] (Berkeley)<br />
|''[[Applied/ACMS/absF19#Lin Lin (UC Berkeley)|TBA]]''<br />
| Li<br />
|-<br />
|}<br />
<br />
== Future semesters ==<br />
<br />
*[[Applied/ACMS/Spring2020|Spring 2020]]<br />
<br />
== Archived semesters ==<br />
*[[Applied/ACMS/Spring2019|Spring 2019]]<br />
*[[Applied/ACMS/Fall2018|Fall 2018]]<br />
*[[Applied/ACMS/Spring2018|Spring 2018]]<br />
*[[Applied/ACMS/Fall2017|Fall 2017]]<br />
*[[Applied/ACMS/Spring2017|Spring 2017]]<br />
*[[Applied/ACMS/Fall2016|Fall 2016]]<br />
*[[Applied/ACMS/Spring2016|Spring 2016]]<br />
*[[Applied/ACMS/Fall2015|Fall 2015]]<br />
*[[Applied/ACMS/Spring2015|Spring 2015]]<br />
*[[Applied/ACMS/Fall2014|Fall 2014]]<br />
*[[Applied/ACMS/Spring2014|Spring 2014]]<br />
*[[Applied/ACMS/Fall2013|Fall 2013]]<br />
*[[Applied/ACMS/Spring2013|Spring 2013]]<br />
*[[Applied/ACMS/Fall2012|Fall 2012]]<br />
*[[Applied/ACMS/Spring2012|Spring 2012]]<br />
*[[Applied/ACMS/Fall2011|Fall 2011]]<br />
*[[Applied/ACMS/Spring2011|Spring 2011]]<br />
*[[Applied/ACMS/Fall2010|Fall 2010]]<br />
<!--<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring10.html Spring 2010]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall09.html Fall 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring09.html Spring 2009]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall08.html Fall 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring08.html Spring 2008]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall07.html Fall 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Spring07.html Spring 2007]<br />
*[http://www.math.wisc.edu/~jeanluc/ACMS/archive/Fall06.html Fall 2006]<br />
--><br />
<br />
<br><br />
<br />
----<br />
Return to the [[Applied|Applied Mathematics Group Page]]</div>Spagnoliehttps://www.math.wisc.edu/wiki/index.php?title=Applied/ACMS/absF19&diff=18325Applied/ACMS/absF192019-11-04T17:24:33Z<p>Spagnolie: /* ACMS Abstracts: Fall 2019 */</p>
<hr />
<div>= ACMS Abstracts: Fall 2019 =<br />
<br />
=== Leonardo Andrés Zepeda Núñez ===<br />
<br />
Title: Deep Learning for Electronic Structure Computations: A Tale of Symmetries, Locality, and Physics<br />
<br />
Abstract: Recently, the surge of interest in deep neural learning has dramatically improved image and signal processing, which has fueled breakthroughs in many domains such as drug discovery, genomics, and automatic translation. These advances have been further applied to scientific computing and, in particular, to electronic structure computations. In this case, the main objective is to directly compute the electron density, which encodes most of information of the system, thus bypassing the computationally intensive solution of the Kohn-Sham equations. However, similar to neural networks for image processing, the performance of the methods depends spectacularly on the physical and analytical intuition incorporated in the network, and on the training stage.<br />
<br />
In this talk, I will show how to build a network that respects physical symmetries and locality. I will show how to train the networks and how such properties impact the performance of the resulting network. Finally, I will present several examples for small yet realistic chemical systems.<br />
<br />
<br />
=== Daniel Floryan (UW-Madison) ===<br />
<br />
Title: Flexible Inertial Swimmers<br />
<br />
Abstract: Inertial swimmers deform their bodies and fins to push against the water and propel themselves forward. The deformation is driven partly by active musculature, and partly by passive elasticity. The interaction between elasticity and hydrodynamics confers features on the swimmers not enjoyed by their rigid friends, for example, boosts in speed when flapping at certain frequencies. We explain the salient features of flexible swimmers by drawing ideas from airfoils, vibrating beams, and flags flapping in the wind. The presence of fluid drag has important consequences. We also explore optimal arrangements of flexibility. (It turns out that nature is quite good.)<br />
<br />
<br />
=== Jianfeng Lu (Duke) ===<br />
<br />
Title: How to ``localize" the computation?<br />
<br />
It is often desirable to restrict the numerical computation to a local <br />
region to achieve best balance between accuracy and affordability in scientific computing. It is important to avoid artifacts and guarantee predictable modelling while artificial boundary conditions have to be introduced to restrict the computation. In this talk, we will discuss some recent understanding on how to achieve such local computation in the context of topological edge states and elliptic random media.<br />
<br />
<br />
=== Mitch Bushuk (GFDL/Princeton) ===<br />
<br />
Title: Arctic Sea Ice Predictability in a Changing Cryosphere<br />
<br />
Abstract: Forty years of satellite observations have documented a striking decline in the areal extent of Arctic sea ice. The loss of sea ice has impacts on the climate system, human populations, ecosystems, and natural environments across a broad range of spatial and temporal scales. These changes have motivated significant research interest in the predictability and prediction of Arctic sea ice on seasonal-to-interannual timescales. In this talk, I will address two related questions: (1) What is the inherent predictability of Arctic sea ice and what physical mechanisms underlie this predictability? and (2) How can this knowledge be leveraged to improve operational sea ice predictions? I will present findings on the relative roles of the ocean, sea ice, and atmosphere in controlling Arctic sea ice predictability. I will also present evidence for an Arctic spring predictability barrier, which may impose a sharp limit on our ability to make skillful predictions of the summer sea ice minimum. <br />
<br />
<br />
=== Qin Li (UW-Madison) ===<br />
<br />
Title: The power of randomness in scientific computing<br />
<br />
Abstract: Most numerical methods in scientific computing are deterministic. Traditionally, accuracy has been the target while the cost was not the concern. However, in this era of big data, we incline to relax the strict requirements on the accuracy to reduce numerical cost. Introducing randomness in the numerical solvers could potentially speed up the computation significantly at small sacrifice of accuracy. In this talk, I'd like to show two concrete examples how this is done: first on random sketching in experimental design, and the second on numerical homgenization, hoping the discussion can shed light on potential other applications. Joint work with Ke Chen, Jianfeng Lu, Kit Newton and Stephen Wright.<br />
<br />
<br />
=== Joel Nishimura (Arizona State) ===<br />
<br />
Title: Random graph models with fixed degree sequences: choices, consequences and irreducibility proofs for sampling<br />
<br />
Abstract: Determining which features of an empirical graph are noteworthy frequently relies upon the ability to sample random graphs with constrained properties. Since empirical graphs have distinctive degree sequences, one of the most popular random graph models is the configuration model, which produces a graph uniformly at random from the set of graphs with a fixed degree sequence. While it is commonly treated as though there is only a single configuration model, one sampled via stub-matching, there are many, depending on whether self-loops and multiedges are allowed and whether edge stubs are labeled or not. We show, these different configuration models can lead to drastically, sometimes opposite, interpretations of empirical graphs. In order to sample from these different configuration models, we review and develop the underpinnings of Markov chain Monte Carlo methods based upon double-edge swaps. We also present new results on the irreducibility of the Markov chain for graphs with self-loops, either proving irreducibility or exactly characterizing the degree sequences for which the Markov chain is reducible. This work completes the study of the irreducibility of double edge-swap Markov chains (and the related Curveball Markov chain) for all combinations of allowing self-loops, multiple self-loops and/or multiedges. <br />
<br />
<br />
=== Alex Townsend (Cornell) ===<br />
<br />
Title: Why are so many matrices and tensors of low rank in computational mathematics?<br />
<br />
Abstract: Matrices and tensors that appear in computational mathematics are so often well-approximated by low-rank objects. Since random ("average") matrices are almost surely of full rank, mathematics needs to explain the abundance of low-rank structures. We will give various methodologies that allow one to begin to understand the prevalence of compressible matrices and tensors and we hope to reveal an underlying link between disparate applications. In particular, we will show how one can connect the singular values of a matrix with displacement structure to a rational approximation problem that highlights fundamental connections between polynomial interpolation, Krylov methods, and fast Toeplitz solvers.<br />
<br />
<br />
=== Prashant G. Mehta ===<br />
<br />
Title: What is the Lagrangian for Nonlinear Filtering?<br />
<br />
Abstract: There is a certain magic involved in recasting the equations in Physics, and the algorithms in Engineering, in variational terms. The most classical of these ‘magics’ is the Lagrange’s formulation of the Newtonian mechanics. An accessible modern take on all this and more appears in the February 19, 2019 issue of The New Yorker magazine: https://www.newyorker.com/science/elements/a-different-kind-of-theory-of-everything?reload=true <br />
<br />
My talk is concerned with a variational (optimal control type) formulation of the problem of nonlinear filtering/estimation. Such formulations are referred to as duality between optimal estimation and optimal control. The first duality principle appears in the seminal (1961) paper of Kalman-Bucy, where the problem of minimum variance estimation is shown to be dual to a linear quadratic optimal control problem. <br />
<br />
In my talk, I will describe a generalization of the Kalman-Bucy duality theory to nonlinear filtering. The generalization is an exact extension, in the sense that the dual optimal control problem has the same minimum variance structure for linear and nonlinear filtering problems. Kalman-Bucy’s classical result is shown to be a special case. During the talk, I will also attempt to review other types of duality relationships that have appeared over the years for the problem of linear and nonlinear filtering. <br />
<br />
This is joint work with Jin Won Kim and Sean Meyn. The talk is based on the following papers: https://arxiv.org/pdf/1903.11195.pdf and https://arxiv.org/pdf/1904.01710.pdf.<br />
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=== Jean-Luc Thiffeault ===<br />
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Title: Shape matters: A Brownian swimmer in a channel<br />
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Abstract: We consider a simple model of a two-dimensional microswimmer with fixed swimming speed. The direction of swimming changes according to<br />
a Brownian process, and the swimmer is interacting with boundaries. This is a standard model for a simple microswimmer, or a confined<br />
wormlike chain polymer. The shape of the swimmer determines the range of allowable values that its degrees of freedom can assume --- its<br />
configuration space. Using natural assumptions about reflection of the swimmer at boundaries, we compute the swimmer's invariant<br />
distribution across a channel consisting of two parallel walls, and the statistics of spreading in the longitudinal direction. This gives<br />
us the effective diffusion constant of the swimmer's large scale motion. When the swimmer is longer than the channel width, it cannot<br />
reverse, and we then compute the mean drift velocity of the swimmer. This model offers insight into experiments of scattering of swimmers<br />
from boundaries, and serves as an exactly-solvable baseline when comparing to more complex models. This is joint work with Hongfei Chen.<br />
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=== Tan Bui (UT-Austin) ===<br />
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Title: Scalable Algorithms for Data-driven Inverse and Learning Problems<br />
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Abstract: Inverse problems and uncertainty quantification (UQ) are pervasive in scientific discovery and decision-making for complex, natural, engineered, and societal systems. They are perhaps the most popular mathematical approaches for enabling predictive scientific simulations that integrate observational/experimental data, simulations and/or models. Unfortunately, inverse/UQ problems for practical complex systems possess these the simultaneous challenges: the large-scale forward problem challenge, the high dimensional parameter space challenge, and the big data challenge.<br />
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To address the first challenge, we have developed parallel high-order (hybridized) discontinuous Galerkin methods to discretize complex forward PDEs. <br />
To address the second challenge, we have developed various approaches from model reduction to advanced Markov chain Monte Carlo methods to effectively explore high dimensional parameter spaces to compute posterior statistics. To address the last challenge, we have developed a randomized misfit approach that uncovers the interplay between the Johnson-Lindenstrauss and the Morozov's discrepancy principle to significantly reduce the dimension of the data without compromising the quality of the inverse solutions.<br />
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In this talk we selectively present scalable and rigorous approaches to tackle these challenges for PDE-governed Bayesian inverse problems. Various numerical results for simple to complex PDEs will be presented to verify our algorithms and theoretical findings. If time permits, we will present our recent work on scientific machine learning for inverse and learning problems.<br />
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=== Wenxiao Pan (UW-Madison) ===<br />
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Title: Mesoscale Modeling of Soft Matter<br />
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Abstract: Soft matter systems, such as colloids and polymers, are characterized by an interplay of interactions and processes that span a wide range of length- and time scales. Computer simulations require modeling approaches to cover these scales. In order to access mesoscopic time- and length scales, necessary to access material properties, two numerical approaches will be discussed in this talk. The first one concerns suspension flows of arbitrary-shaped colloids. A high-order, spatially adaptive, meshless method was developed to solve the PDEs that govern hydrodynamics and fluid- solid interactions. Near-field hydrodynamic interactions between arbitrary-shaped colloids can be accurately captured without subgrid-scale lubrication models. The second approach seeks a bottom-up, coarse-grained modeling for polymers in solution. It starts from atomistic descriptions, and by proper mapping atomistic details onto a coarser representation, arrives at the mesoscale. The effect of unresolved degrees of freedom on the kinetics of polymers is accounted by the non-Markovian memory kernel. The coarse-grained variables and governing equation are directly linked to the statistics of atomistic data.</div>Spagnolie