Stokes waves with constant vorticity: numerical computation

Speaker: 

Vera Mikyoung Hur

Institution: 

UIUC

Time: 

Monday, June 5, 2017 - 4:00pm

Host: 

Location: 

RH306

Stokes in his classical memoir made many contributions about periodic traveling waves at the free surface of a water flow. In particular, he conjectured that a wave of greatest possible height would exhibit stagnation with a 120 degree's corner. In the zero vorticity case, Amick, Fraenkel, and Toland answered the conjecture affirmatively. But interior stagnation is not allowed for all waves.

 

The situation becomes much more complicated with non-zero vorticity. Recently, Constantin, Strauss, and Varvaruca worked out global bifurcation in the constant vorticity case, and they conjectured about limiting waves. I will present the joint work with Sergey Dyachenko (Illinois), numerically computing Stokes waves with constant vorticity from zero close to the limiting wave, and discovering new limiting waves.

Three principles of data science: predictability, stability, and computability

Speaker: 

Bin Yu

Institution: 

UC Berkeley

Time: 

Friday, February 3, 2017 - 2:00pm to 3:00pm

Host: 

Location: 

NS2, 1201

In this talk, I'd like to discuss the intertwining importance and connections of three principles of data science in the title in data-driven decisions. The ultimate importance of prediction lies in the fact that future holds the unique and possibly the only purpose of all human activities, in business, education, research, and government alike.
Making prediction as its central task and embracing computation as its core, machine learning has enabled wide-ranging data-driven successes. Prediction is a useful way to check with reality. Good prediction implicitly assumes stability between past and future. Stability (relative to data and model perturbations) is also a minimum requirement for interpretability and reproducibility of data driven results. It is closely related to uncertainty assessment. Obviously, both prediction and stability principles can not be employed without feasible computational algorithms, hence the importance of computability. The three principles will be demonstrated through analytical connections, and in the context of two on-going neuroscience projects, for which "data wisdom" is also indispensable. Specifically, the first project interprets a predictive model used for reconstruction
of movies from fMRI brain signals; the second project employs deep learning networks (CNNs) to understand pattern selectivities of neurons in the difficult visual cortex V4.

Professor Richard Schoen awarded the 2017 Wolf Prize in Mathematics

Professor Richard Schoen, the Excellence in Teaching Chair in the Department of Mathematics at UCI, has been awarded the 2017 Wolf Prize in Mathematics (AMS announcement). The 2017 award will be shared with Charles Fefferman from Princeton. Professor Schoen is receiving the award for his contributions to geometric analysis and the understanding of the interconnectedness of partial differential equations and differential geometry. 
 

Stochastic aspects of curvature flows

Speaker: 

Rob Neel

Institution: 

Lehigh University

Time: 

Tuesday, February 28, 2017 - 4:00pm

Host: 

Location: 

RH306

We begin by discussing the natural diffusion associated to mean curvature flow and work of Soner and Touzi showing that, in Euclidean space, this stochastic structure allows one to reformulate mean curvature flow as the solution to a type of stochastic target problem. Then we describe work with Ionel Popescu adapting the target problem formulation to Ricci flow on compact surfaces and using the accompanying diffusion to understand the convergence of the normalized Ricci flow. We aim to avoid being overly technical, instead focusing on the ideas underlying the appearance of stochastic objects in the context of curvature flow.

An introduction to Carleman estimates

Speaker: 

Katya Krupchyk

Institution: 

UC Irvine

Time: 

Friday, January 27, 2017 - 4:00pm

Location: 

MSTB 124

The origins of Carleman estimates lie with the pioneering 1939 work by the Swedish mathematician T. Carleman, concerned with the unique continuation property for solutions for linear elliptic partial differential equations with smooth coefficients in dimension two. The fundamental new idea introduced by Carleman, which consists of establishing a priori energy estimates involving an exponential weight, has permeated essentially all the subsequent work in the subject. More recently, Carleman estimates have found numerous striking applications beyond the original domain of unique continuation, from control theory to spectral theory to the analysis of inverse problems. The purpose of this talk is to provide a broad introduction to the subject and to attempt to illustrate some of its inner workings.

Absolutely continuous spectrum and the spectra of periodic approximants

Speaker: 

Yoram Last

Institution: 

Hebrew University

Time: 

Thursday, February 9, 2017 - 2:00pm

Location: 

RH 340P

We discuss relations between absolutely continuous spectrum of discrete one-dimensional
Schroedinger operators and the spectra of periodic approximants made by cutting and
repeating
finite pieces of the potential.

Mean curvature flow in bundle manifolds of special holonomy

Speaker: 

Chung-Jun Tsai

Institution: 

National Taiwan University

Time: 

Tuesday, February 7, 2017 - 4:00pm

Location: 

RH 306

In manifolds with special holonomy, it is interesting to
study calibrated submanifolds, which are volume minimizer in their
homology classes. We study the calibrated submanifolds and mean
curvature flow in several famous local models of manifolds with
special holonomy. These model spaces are all total spaces of some
vector bundles, and the zero section is a calibrated submanifold. We
show that the zero section is the only compact minimal submanifold,
and is dynamically stable under the mean curvature flow. This is a
joint work with Mu-Tao Wang.

University Mathematics in the Digital Age

Speaker: 

Steven Heilman

Institution: 

UCLA

Time: 

Tuesday, January 10, 2017 - 3:00pm to 4:00pm

Host: 

Location: 

RH 306

We will discuss my experience and plans for teaching mathematics to students with increasing dependence on the internet. For example, we will discuss my use of online, hyperlinked lecture notes, the role of math.stackexchange.com and other websites for writing homeworks and exams, etc.  Some new course proposals will be given, including an increased role of the math department for the UCI Data Science Initiative.
 

Stability and sparsity in sets of natural numbers

Speaker: 

Gabriel Conant

Institution: 

Notre Dame

Time: 

Monday, March 13, 2017 - 4:00pm

Location: 

RH 440R

The additive group of integers is a well-studied example of a stable group, whose definable sets can be easily and explicitly described. However, until recently, very little has been known about stable expansions of this group. In this talk, we examine the relationship between model-theoretic stability of expansions of the form (Z,+,0,A), where A is a subset of the natural numbers, and the number theoretic behavior of A with respect to sumsets, asymptotic density, and arithmetic progressions.

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