Seminars and Colloquiums
for the week of February 18, 2008
Speakers:
Professor Xia Chen, Monday
Dr. Diego del-Castillo-Negrete, Monday
Mr. Chris Sass, Monday
Professor Chuck Collins, Tuesday
Dr. Mark Abramson, Wednesday
Professor David Anderson, Wednesday
Professor Maria Westdickenberg, Thursday
Monday, February 18
PROBABILITY SEMINAR
TIME: 10:10 – 11:00 a.m.
ROOM: Ayres 309A
SPEAKER: Professor Xia Chen
TITLE: “Limit Laws For The Energy Of A Charge Polymer” (continuation)Fe
ABSTRACT: In the physics literature, the geometric shape of certain polymers is often modeled by an interpolation line segment with the vertice given as the n-step lattice (simple) random walk. Place a random electric charge – 1 or 1 to each of n vertice of the polymer and suppose that the random charges forms an i.i.d. sequence independent of the polymer. Assume that when two charges meet, the pair with opposite sign gives negative contribution while the pair with same sign gives positive contribution. In this talk, I will speak on some recent progress on the limit laws for the total charges of the polymer generated in this way of interaction.
DE/COMPUTATIONAL AND APPLIED MATH SEMINAR
TIME: 3:35 p.m.
ROOM: Ayres 104
SPEAKER: Diego del-Castillo-Negrete, ORNL
TITLE: “Front dynamics in reaction-diffusion systems with fractional diffusion”
ANALYSIS SEMINAR
TIME: 3:35 – 4:25 p.m.
ROOM: Ayres 209A
SPEAKER: Chris Sass
TITLE: “Smale's Mean Value Conjecture, II”
Tuesday, February 19
JUNIOR COLLOQUIUM
TIME: 3:40 – 4:30 p.m.
ROOM: Ayres 214
SPEAKER: Professor Charles Collins
TITLE: “Mathematics and the Bendy Straw”
ABSTRACT: The Bendy Straw: everyone has seen it, played with it and used it, but did you know that it is a great tool for understanding some deep mathematics and science? We'll explore the bendy straw and how it relates to measures, generalized functions, optimization and modern material science.
(Bendy straws will be provided)
Wednesday, February 20
COLLOQUIUM
TIME: 3:35 – 4:25 p.m.
ROOM: Ayres 214
SPEAKER: Mark Abramson, Air Force Institute of Technology,
Wright-Patterson AFB, Ohio
TITLE: “Mesh Adaptive Direct Search Algorithms for Constrained Mixed Variable Optimization”
ABSTRACT: In this talk, we target a class of mixed variable optimization problems in which the objective and constraint functions may be nonsmooth, discontinuous, extended valued, computationally expensive to evaluate, given as a black box, provide few significant digits of accuracy, and may even fail to return a value. Furthermore, constraint functions may return only a yes/no value, derivatives are generally unavailable, and variables may be a mix of continuous, integer, or nonnumeric categorical types (such as color, shape, or type of material). Our approach for solving problems of this type is the derivative-free class of mesh adaptive direct search algorithms. We present the class of algorithms, describe its first-order and second-order theoretical convergence properties, and give some numerical results on some test problems that come from homeland security applications.
ALGEBRA SEMINAR
TIME: 3:35 – 4:25 p.m.
ROOM: Ayres 309A
SPEAKER: Professor David Anderson
Professor David Anderson will continue talking about ultrafilters and ultraproducts in commutative ring theory.
Thursday, February 21
MATHEMATICS COLLOQUIUM
TIME: 3:40 p.m.
ROOM: Ayres 214
SPEAKER: Maria Westdickenberg, GA Institute of Technology
TITLE: “Entropy dissipation and the logarithmic Sobolev inequality”
ABSTRACT: Consider a lattice of random ``spin variables'' evolving in time, modeling for instance the alignment or misalignment of the spins of many electrons. Suppose that the system is relaxing towards a unique equilibrium distribution, and one is interested in the rate at which the relaxation occurs. A natural way to quantify the relaxation is to measure the dissipation of the mathematical entropy (the negative of the physical entropy). The logarithmic Sobolev inequality (LSI) introduced by Gross is a powerful tool for studying entropy dissipation---In fact, it yields an exponential rate. We will survey a few fundamental criteria for LSI and discuss two new sufficient conditions.
This talk includes joint work with Natalie Grunewald, Felix Otto, and C'edric Villani.
Interested in giving or arranging a talk? Check out our calendar.
Previous Announcements:
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Seminars from 2006-2007 academic year