shadow_tr
               

Events This Week


Past Year Events of the Week

Week of March 27 - March 31, 2017
Friday, March 31

Topic

Speaker - Institution

Abstract: 

Location:

Time:


Thursday, March 30

Topic

Speaker - Institution

Abstract: 

Location:

Time:


Thursday, March 30

Topic

Speaker - Institution

Abstract: 

Location:

Time:


Wednesday, March 29

Topic

Speaker - Institution

Abstract: 

Location:

Time:


Tuesday, March 28

Topic

Speaker - Institution

Abstract: 

Location:

Time:


Monday, March 27

Topic

Speaker - Institution

Abstract: 

Location:

Time:


Week of March 24 - March 20, 2017
Friday, March 24

Topic

Speaker - Institution

Abstract: 

Location:


Time:


Thursday, March 23

Colloquium

Nonuniqueness of weak solutions to the SQG equation

Vlad Vicol - Princeton  (Host Nathan Glatt-Holtz)

Abstract:


We prove that weak solutions of the inviscid SQG equations are not unique, thereby answering an open problem posed by De Lellis and Szekelyhidi Jr. Moreover, we show that weak solutions of the dissipative SQG equation are not unique, even if the fractional dissipation is stronger than the square root of the Laplacian. This talk is based on a joint work with T. Buckmaster and S. Shkoller.

Location: Dinwiddie 102

Time:  3:30


Thursday, March 23

Algebra & Combinatoric seminar

Points, symbolic powers and a conjecture by G. V. Chudnovsky.

Paolo Mantero - University of Arkansas

Abstract:

What is the smallest possible degree of an equation passing at least m times through t given points in the complex projective space P^N? The answer is not known (except in few special cases), however the complex analyst G. V. Chudnovsky in 1979 conjectured a lower bound, which until last year was only known to hold for points in P^2, general points in P^3 and certain extremal configurations in P^N.

In this talk we will survey the evolving framework of conjectures and results around the above question, and prove Chudnovsky's conjecture for any set of very general points in P^N.

Location: Gibson Hall 400A

Time:  12:45


Wednesday, March 22

Probability and Statistics

Long and medium time behavior of stochastically modeled biochemical reaction networks

David Anderson - University of Wisconsin

Abstract:


If the abundances of the constituent molecules of a biochemical reaction system  are sufficiently high then their concentrations are typically modeled by a coupled set of ordinary differential equations (ODEs).  If, however, the abundances are low then the standard deterministic models do not provide a good representation of the behavior of the system and stochastic models are used.

In this talk, I will focus on stochastic models of biochemical reaction systems and discuss two topics.  In the first, I will provide a large class of interesting nonlinear models for which the stationary distribution can be solved for explicitly.  Such results are particularly useful for averaging purposes in multi-scale settings.  The second topic will pertain to an interesting class of models that exhibits fundamentally different long-term behavior when modeled deterministically or stochastically (the ODEs predict stability, the stochastic model goes extinct with probability one).  Recent work pertaining to the distribution of the stochastic model on compact time intervals (similar to the study of the quasi-stationary distribution) resolves the apparent discrepancy between the modeling choices.


Location:  Gibson 126

Time:  3:00


Tuesday, March 21

Thermal Stratification in Geophysical Fluid Flows

Speaker - Institution

Abstract:


The two-dimensional incompressible Boussinesq equations have been routinely used to model systems across a tremendous range of length and time scales from microfluidics and biophysics to geodynamics and astrophysics. It plays an important role in the study of atmospheric and oceanographic turbulence as well as other situations where rotation and stratification play a dominant role. In addition to its own physical background, the model is also known for its close connection with fundamental models in mathematical fluid mechanics, such as the incompressible Euler and Navier-Stokes equations. In a special situation, the vortex formulation of this two-dimensional model in Eulerian coordinates is formally identical to the vortex formulation of the three-dimensional Euler equations in cylindrical coordinates for axisymmetric swirling fluid flows, which makes it a tremendously rich area for mathematical investigations. This talk focuses on the rigorous mathematical demonstration of one of the common phenomena in geophysical fluid flows:  thermal (vertical) stratification. After introducing the background, the proof will be fully explained, which only requires knowledge of calculus and real analysis. Some open problem and numerical experiments will be exposed towards the end of the talk.


Location:  Dinwiddie Hall

Time: 2:00


Tuesday, March 21

Student Colloquium

Useful Result for Regularity of Edge Ideals


Joseph Skelton  - Tulane University

Abstract:

The talk will cover fundamental definitions relating to the regularity of edge ideals, as well as cover a useful result for the bounds of regularity.

Location:  Stanley Thomas 316

Time:  4:15


Monday, March 20

Topic


Speaker - Institution

Abstract: 

Location:

Time:


Week of March 18 - March 13, 2017
Saturday, March 18

SCALA



Friday, March 17

SCALA



Thursday, March 16

Topic

Speaker - Institution

Abstract: 

Location:

Time:


Thursday, March 16

Colloquium

Non-Archimedean analytic curves in algebraic varieties

Prof. William Cherry - University of North Texas (Host: Tai Ha)

Abstract:


I will explain Serge Lang's conjectures relating four aspects of algebraic varieties: geometric structure, rational maps from group varieties, rational points, and holomorphic maps from the complex plane. I will then explain what happens if one considers non-Archimedean analytic maps instead of complex holomorphic maps and discuss a parallel conjectural framework. I will give a broad overview and intend that the talk will be accessible even to those with limited experience with algebraic geometry and non-Archimedean analysis.


Location:  Dinwiddie 102

Time:  3:30


Wednesday, March 15

Probability and Statistics  (Joint with Applied Math)

Asymptotic analysis for randomly forced magnetohydrodynamics


Susan Friedlander - University of Southern California

Abstract:


We consider the three dimensional magnetohydrodynamics (MHD) equations in the presence of stochastic forcing as a model for magnetostrophic turbulence. For scales relevant to the Earth's fluid core this MHD system is very rich in small parameters. We discuss results concerning the asymptotics of the stochastically forced PDEs in the limit of vanishing parameters. In particular we establish that the system sustains ergodic statistically steady states thus providing a rigorous foundation for magnetostrophic turbulence.


Location:  Gibson 126

Time: 3:00


Tuesday, March 14

Graduate Student Colloquium

Everything You Always Wanted to Know About Pi (But Were Afraid to Ask)

Aram Bingham - Tulane University

Abstract:

Imagine all of the internet burns down, with all the books inside it, and we have to recreate the current state of mathematics with our bare brains. What facts about pi (pronounced pee) will we retain? After reciting some of the trivia which is Pi Day orthodoxy, we will discuss proofs of those aspects of pi we take most for granted, making reference to open problems as well.

 Location: Stanley Thomas 316



Time:   4:15


Monday, March 13

Probability and Statistics  (Special Day)

Transition probabilities for degenerate diffusions arinsing in population genetics

Camelia Pop - University of Minnesota  (Host Scott McKinley)

Abstract:

 

We provide a detailed description of the structure of the transition probabilities and of the hitting distributions of boundary components of a manifold with corners for a degenerate strong Markov process arising in population genetics. The Markov processes that we study are a generalization of the classical Wright-Fisher process. The main ingredients in our proofs are based on the analysis of the regularity properties of solutions to a forward Kolmogorov equation defined on a compact manifold with corners, which is degenerate in the sense that it is not strictly elliptic and the coefficients of the first order drift term have mild logarithmic singularities. This is joint work with Charles Epstein.


Location:  Stanley Thomas 316

Time:  4:00


Week of March 10 - March 6, 2017
Friday, March 10

Topic

Speaker - Institution

Abstract: 

Location:

Time:


Thursday, March 9

The sound of silence — Recovering signals from time-frequency zeros

Patrick FlandrinCNRS and ENS-Lyon (host: Didier Gustavo)

Abstract:


Disentangling multicomponent nonstationary signals into coherent AM-FM modes is usually achieved by identifying « loud » time-frequency trajectories where energy is locally maximum. We will here present an alternative perspective that relies on « silent » points, namely spectrogram zeros. Based on the theory of Gaussian analytic functions, a number of results will be presented regarding the distribution of such zeros considered as a point process in the plane, with repulsive properties. The rationale and the implementation of the zeros-based approach for recovering signals embedded in noise will then be discussed, with an application to the extraction and characterization of actual gravitational wave chirps.

Location: Dinwiddie 102

Time: 3:30


Thursday, March 9

A DYNAMIC BUCHBERGER ALGORITHM

John Perry | University of Southern Mississippi

Abstract:

Gröbner bases are a major tool in commutative algebra, typically computed using the Buchberger algorithm. This algorithm is “static” in that it works with a fixed term ordering, required as input along with the ideal’s generators. In many cases, however, a “dynamic” Buchberger algorithm is more appropriate: it requires only the generators as input, and returns both a basis and an ordering that guarantees the Gröbner property. It computes the ordering by the guidance of a criterion inspired by an invariant of an ideal. This talk describes the algorithm, the traditional criterion to guide computation, and a new criterion.

Location: Gibson Hall 400A

Time:  12:45


Wednesday, March 8

Simulating the Mean Efficiently and to a Given Tolerance

Fred Hickernell - Illinois Institute of Technology (HOST James Hyman)

Abstract:


Various application problems are formulated as means of random variables, e.g., option pricing, multivariate probabilities, and Sobol' indices. When the distribution of the random variable is complicated, computer simulation can be used to approximate the population mean by a sample mean.  Two big questions are how to draw the sample to minimize error, and what sample size is needed to guarantee the desired accuracy.  This talk describes our best answers so far.  The sampling error can be decomposed into a product of three factors. 

One of these factors, the discrepancy, describes the efficiency of simulation.  By assuming that the distribution of the random variable is nice, in some mathematically precise way, we can rigorously bound the error of the simulation and thus determined the sample size required.


Location: Gibson 126

Time:  3:00


Monday, March 7

Topic

Diego Villamizar - Tulane University

Abstract:

I will talk about r-indecomposable factorial numbers, and how I do not know anything about them.

Location: Stanley Thomas 316

Time:  4:15


Tuesday, March 7

Tulane AWM/AMS Student Chapters present:

Applications of computational geometry and topology in shape matching

Dr Carola Wenk - Tulane University

Abstract:


Abstract: In this talk we will discuss approaches of computational geometry and topology to theory and applications of geometric shape matching. This includes the Frechet distance for curves, the use of persistent homology, and applications in map construction and comparison.

Location: Dinwiddie 102

Time: 2:00


Monday, March 6

Topic

Speaker - Institution

Abstract: 

Location:

Time:



Week of March 3 - February 27, 2017


Friday, March 3

Topic

Speaker - Institution

Abstract: 

Location:

Time:


Thursday, March 2

Algebra & Combinatorics

The depth function of ideals in polynomial rings.

Tai Huy Ha - Tulane University

Abstract:

We shall discuss what could be the depth function of an ideal in a polynomial ring. That is, for which function f(n), there exists an ideal I in a polynomial ring R such that depth R/I^n = f(n) for all n > 0.

Location: Gibson 400A

Time: 12:45


Thursday, March 2

Topic

Speaker - Institution

Abstract: 

Location:

Time:


Wednesday, February 1

Topic

Speaker - Institution

Abstract: 

Location:

Time:


Tuesday, February 28

Mardi Gras Break


All University Offices will be closed

Have a safe Holiday

 


Monday, February 27

Mardi Gras Break


All University Offices will be closed

Have a safe Holiday


Week of February 24 - February 20, 2017

Friday, February 24

Topic

Speaker - Institution

Abstract: 

Location:

Time:


Thursday, February 23

Colloquium

Why is the ergodic theory of stochastic PDEs different?

Jonathan Mattingly - Duke (HOST: Nathan Glatt-Holtz and Scott McKinley)

Abstract:

Ergodicity is one of the fundamental questions for a stochastic dynamical  system,  ensuring the convergence of  long time averages of observable quantities to a statistical steady state independent of the initial condition.

I will explore why the ergodic theory of stochastic PDEs is different and how it underlines the basic difference between ODEs and PDEs. I will start at the beginning giving a crash course on the basic elements needed to prove an ergodic result.  We will come to understand why sometimes ergodicity can be easy for hard PDEs. Time permitting I will touch on hypoellipticity in infinite dimensions and singular PDEs.

Location: Dimwiddie 102

Time: 3:30


Thursday, February 23

Topic

Speaker - Institution

Abstract: 

Location:

Time:


Wednesday, February 22

Topic

Hung Nguyen - Tulane University

Abstract: 

Location: Gibson Hall

Time: 3:00


Tuesday, February 21

Secret Meeting of the L5 Society

Kristi Vandusen and Padi Fuster - Tulane University

Abstract:

Secret Meeting of the L5 Society

Location: Stanley Thomas 316

Time: 4:15


Monday, February 20

Topic

Speaker - Institution

Abstract: 

Location:

Time:

Week of February 17 - February 13, 2017
Friday, February 17

Topic

Speaker - Institution

Abstract: 

Location:

Time:


Thursday, February 16

Algebra and Combinatorics Seminar


Classification of spherical diagonal actions of reductive groups, Part II.

Mahir Bilen Can - Tulane University

Abstract:


In this talk we present our recent progress on the diagonal actions of a reductive groups on product varieties of the form X_1 x X_2, where X_1 is a symmetric space and X_2 is a partial flag variety.  In particular, we classify all such actions.

Location:  Gibson Hall 400A

Time: 12:45


Wednesday, February 15

Continuum approximation of invasion probabilities for stochastic population models

Rebecca Borchering - University of Florida

Abstract:


When an individual with a novel trait is introduced in a new environment, we would like to understand what drives the likelihood that its lineage will persist. In deterministic population models, whether the invasive population “succeeds” often depends on whether the parameters of the system fall in a super- or sub-critical regime.  In stochastic population models, the parameters must be super-critical for there to be a substantial of invasion, but even in the super-critical regime, chance alone allows for many invasive lineages to quickly go extinct.

In this talk, we compare popular continuum approximations for the invasion probability to its exact solution. In particular, methods known as "Diffusion (or Stochastic Differential Equation) Approximation" and "Exponential Approximation" are derived. We find analytical expressions for these approximations in the large population limit and then use numerical methods to evaluate the performance of the approximation methods for finite populations.  Interestingly we find that the diffusion approximation fails to obtain the correct large population limit, but can perform well for small populations that experience near critical dynamics.  The exponential approximation obtains the right large population limit in the supercritical regime, but fails to capture nonmontonic characteristics of the invasion probability for small to intermediate sized populations. 


Location: Gibson 126

Time: 3:00


Wednesday, February 14

GRAD STUDENT COLLOQUIUM

Lasso, Group Lasso, and SLOPE

Lin Li - Tulane University

Abstract:


From linear regression, I will introduce the penalty method such as ridge method and lasso method. However, in some cases, the variates have strong correlation with each other, then we can use the group lasso. After that, I will talk about SLOPE(sorted L-One Penalty Estimation), which is method similar to the lasso method and consider the false discovery rate as the criteria.

Location: Stanley Thomas 316

Time: 4:15



Tuesday, February 14

Tulane AWM/AMS Student Chapter present:


COFFEE AND DISCUSSION: “Finding opportunities for conferences, workshops, etc”

Speaker - Institution

Abstract:

"We will be discussing effective ways to find and apply for conferences, workshops, and summer programs, including opportunities that are offered in collaboration with AWM.  Topics include attending the joint meetings, MSRI's, Advance grant workshops, area specific conferences/workshops, how to stay informed of future opportunities, and how to apply for funding."


Location: Dinwiddie Hall 102

Time: 2:00


Monday, February 13

Special Mathematical Biology seminar

Diabetes: One Disease, Many Paths

Dr. Arthur Sherman - National Institutes of Health

Abstract: 

Location:  Stanley Thomas 316

Time:  3:00



Week of February 10 - February 6, 2017
Friday, February 10

Topic

Speaker - Institution

Abstract: 

Location:

Time:


Thursday, February 9

Colloquium

Global Regularity v.s. Finite Time Blowup for Compressible Euler Equations

Prof. Ronghua Pan - Georgia Tech (host Kun Zhao)

Abstract:

As one of the oldest nonlinear PDE systems, the compressible Euler equations has been studied by many outstanding mathematicians. However, some basic questions, such as the global existence of classical solution v.s. finite time blowup, are still open even in one space dimension. In this lecture, we will report our recent progress in this direction, including a complete understanding on isentropic flows, and a refreshed understanding on general adiabatic flows. This lecture is based on joint works with H. Cai, G. Chen, S. Zhu, and Y. Zhu.

Location: Dinwiddie 102

Time: 3:30


Wednesday, February 9

Algebra and Combinatorics Seminar


Classification of spherical diagonal actions of reductive groups

Mahir Bilen Can - Tulane University

Abstract:

In this talk we present our recent progress on the diagonal actions of a reductive groups on product varieties of the form X_1 x X_2, where X_1 is a symmetric space and X_2 is a partial flag variety. In particular, we classify all such actions.

Location: Gibson Hall 400A

Time:12:45


Wednesday, February 8

Probability and Statistics

Scalings and saturation in infinite-dimensional control problems with applications to stochastic partial differential equations.

David Herzog - Institution

Abstract:


We discuss scaling methods which can be used to solve low mode control problems for nonlinear partial differential equations.  These methods lead naturally to a infinite-dimensional generalization of the notion of saturation, originally due to Jurdjevic and Kupka in the finite-dimensional setting of ODEs.  The methods will be highlighted by applying them to specific equations, including reaction-diffusion equations, the 2d/3d Euler/Navier-Stokes equations and the 2d Boussinesq equations.  Applications to support properties of the laws solving randomly-forced versions of each of these equations will be noted.

Location: Gibson Hall 126

Time: 3:00


Tuesday, February 7

Graduate Student Colloquium

Poincare Duality With Local Coecients

Fang Sun - Tulane University

Abstract:


Location: Stanley Thomas 316

Time: 4:15


Monday, February 7


TULANE AWM/AMS STUDENT CHAPTERS

Introduction to Riemannian Geometry

DR. DAGANG YANG - Tulaner - Institution

Abstract:

This talk is a brief introduction to Riemannian geometry. Namely, I will explain what is a Riemannian manifold, why should one be interested in Riemannian geometry, the meaning of the sign of the sectional curvature, and some well-known open problems in Riemannian geometry.

Location: Dimwiddie Hall 102

Time: 2:00


Monday, February 6

Topic

Speaker - Institution

Abstract: 

Location:

Time:



Week of February 3 - January 30, 2017

Friday, February 3

Topic

Speaker - Institution

Abstract: 

Location:

Time:

 
Thursday, February 2

Colloquium

Limit Shapes for Rational Functions


Robin Pemantle
University of Pennsylvania  (host mahir can)

Abstract:

Exact enumeration in probability and combinatorics often leads to rational generating functions.  These, in turn, lead to limit shapes, often more exotic than the generic Gaussian shape arising from a Central Limit Theorem.  This motivates the study of the asymptotics of the coefficients of a rational power series

                F(Z) = P(Z) / Q(Z) = sum_R a_R Z^R

where Z = (z_1, ... , z_d) and R = (r_1, ..., r_d) are d-tuples. Estimating a_R from P and Q is both a theoretical problem and a problem in effective computation.  I will discuss what we know about how to read limit shape behavior from P and Q (mostly from Q). The examples in the pictures will all be explained.


02b-octic  06-qrw


aztec256  QRW-2D


Location:  Dinwiddie 102


Time:  3:30



Thursday, February 2

Algebra and Combinatorics Seminar

Introduction to the Hodge Conjecture (part 2)

Al Vitter - Tulane University

Abstract:

This will be a continuation of my first talk. I will state the Hodge Conjecture and then talk about some aspects that show its subtlety and importance. The Hodge Conjecture concerns smooth (non-singular) complex projective varieties. It relates the purely algebraic structure of the variety to its topological/complex-analytic structure via its cohomology groups. I will begin by discussing in a relatively untechnical way, some of the mathematics needed to state clearly the Hodge Conjecture.

Location: Gibson 400A

Time: 1:00



Wednesday, February 1

Topic

Speaker - Institution

Abstract: 

Location:

Time:



Friday, February 31

Graduate Student Colloquium

Some algebraic properties of toric edge rings

Slivi Beyarslan - Tulane University

Abstract:

Student Colloquium

Location:  Stanley Thomas 316

Time: 4:15


Tuesday, January 31

AWM / AMS

Biofluids of reproduction: oscillators, viscoelastic networks and sticky situations.

Dr. Lisa Fauci - Tulane University

Abstract:

From fertilization to birth, successful mammalian reproduction relies on interactions of elastic structures with a fluid environment.  Sperm flagella must move through cervical mucus to the uterus and into the oviduct, where fertilization occurs.  In fact, some sperm may adhere to oviductal epithelia, and must change their pattern of oscillation to escape.  In addition, coordinated beating of oviductal cilia also drives the flow.  Sperm-egg penetration, transport of the fertilized ovum from the oviduct to its implantation in the uterus and, indeed, birth itself are rich examples of elasto-hydrodynamic coupling.   
We will discuss successes and challenges in the mathematical and computational modeling of the biofluids of reproduction.  In addition, we will present reduced models that evoke intriguing questions in fundamental fluid dynamics. 

Location: Dinwiddie 102

Time: 2:00



Monday, January 30

Topic

Speaker - Institution

Abstract: 

Location:

Time:


Week of January 27 - January 23, 2017

Friday, January 27

Topic

Speaker - Institution

Abstract: 

Location:

Time:


Thursday, January 26

Algebra and Combinatorics Seminar

Introduction to the Hodge Conjecture

Al Vitter - Tulane University

Abstract:

This will be the first of probably 2 talks. The Hodge Conjecture concerns smooth (non-singular) complex projective varieties. It relates the purely algebraic structure of the variety to its topological/complex-analytic structure via its cohomology groups. I will begin by discussing in a relatively untechnical way, some of the mathematics needed to state clearly the Hodge Conjecture. Then I will concentrate on some aspects that  bring out (hopefully) the subtlety and importance of the conjecture.

Location: Gibson Hall 400A

Time: 4:00



Wednesday, January 25

Topic

Speaker - Institution

Abstract: 

Location:

Time:


Tuesday, January 24

Graduate Student Colloquium

The Method of Brackets

Victor H. Moll - Tulane University

Abstract:

 Capture22

Location:  Stanley Thomas 316

Time: 4:30


Monday, January 23

Topic

Speaker - Institution

Abstract: 

Location:

Time:


Week of January 20 - January 16, 2017

Friday, January 20

Topic

Speaker - Institution

Abstract: 

Location:

Time:


Thursday, January 20

Sixth Annual Winter Workshop on Neuromechanics and Dynamics of Locomotion


Location:  Lavin Bernick Center for University Life (building 29) - Kendall Cram Room

Thursday, January 19

Sixth Annual Winter Workshop on Neuromechanics and Dynamics of Locomotion


Location:  Lavin Bernick Center for University Life (building 29) - Kendall Cram Room

 


Thursday, January 19

Topic

Speaker - Institution

Abstract: 

Location:

Time:


Wednesday, January 18

Topic

Speaker - Institution

Abstract: 

Location:

Time:


Tuesday, January 17

Topic

Speaker - Institution

Abstract: 

Location:

Time:


Monday, January 16
Martin Luther King Day


Mathematics Department, 424 Gibson Hall, New Orleans, LA 70118 504-865-5727 math@math.tulane.edu