Events Calendar

November 2009
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Events for November 2009:

6 (Friday)	Analysis Seminar Renormalization in the Kondo problem Sarada Rajeev, University of Rochester 2:00 pm - 3:00 pm, Hylan 1106A When electrons in a metal encounter an impurity of small size, the zero temperature resistance is predicted to be infinite by the usual methods of quantum theory. Experimentally, the resistance grows at low temperatures, but remains finite. This contradiction was resolved by Wilson using his celebrated Numerical Renormalization Group method. I will discuss another approach which has the potential of being mathematically rigorous. Some toy models of renormalization with a rigorous mathematical formulation will also be discussed. Tea served at 3:00pm, in the Math Lounge, 9th floor Hylan Bldg.
	Geometry Seminar Scalar Curvature and Connected Sums Of Self-Dual 4-Manifolds Mustafa Kalafat, University of Wisconsin-Madison 4:00 pm - 5:00 pm, Hylan 1106A Under a vanishing hypothesis, Donaldson and Friedman proved that the connected sum of two self-dual Riemannian 4-Manifolds is again self-dual. We prove that the same result can be extended over to the positive scalar curvature case. Tea will be served starting at 3:00pm in the Math Lounge, 9th Floor, Hylan Bldg.
11 (Wednesday)	Probability Study Group The fractal dimension of the zero set of Brownian Motion ( Continuation ) Shannon Starr, U of R 4 pm - 5 pm, Hylan 1106A
12 (Thursday)	Special Lecture Managing and Evaluating Large Introductory Programs Karen Rhea, University of Michigan 2 pm - 3 pm, Hylan 1106B Each year, university departments are faced with the opportunity and challenge of training and mentoring new instructors. Such training and mentoring are critical to the success of the departments’ teaching endeavors, given that programs often rely heavily on graduate students or temporary faculty (postdocs or adjuncts) to teach the bulk of their lower-level courses. In this talk, we will explore some training and mentoring techniques, and talk about some methods of evaluating the effect of training and suggested pedagogical techniques. Tea will be served at 3:00pm in the Math Dept. Lounge, 9th floor, Hylan Bldg.
	Colloquium Twist & Shout: Maximal enstrophy production in the 3D Navier-Stokes Charles Doering 3:30 pm - 4:30 pm, Computer Studies Building 209 It is still not known whether solutions to the 3D Navier-Stokes equations for incompressible flows in a finite periodic box can become singular in finite time. (This question is the subject of one of the $1M Clay Prize problems.) It is known that a solution remains smooth as long as the enstrophy, i.e., the mean-square vorticity, of the solution is finite. The generation rate of enstrophy is given by a functional that can be bounded using elementary functional estimates. Those estimates establish short-time regularity but do not rule out finite-time singularities in the solutions. In this work we formulate and solve the variational problem for the maximal growth rate of enstrophy and display flows that generate enstrophy at the greatest possible rate. Implications for questions of regularity or singularity in solutions of the 3D Navier-Stokes equations are discussed. This is joint work with Lu Lu, Indiana University Mathematics Journal Vol. 57, pp. 2693-2727 (2008). Tea will be served at 3:00pm in the Math Dept. Lounge, 9th floor, Hylan Bldg.
13 (Friday)	Analysis Seminar Eventual regularization of the slightly supercritical fractional Burgers equation. Magdalena Czuback of the University of Toronto. 2 pm - 3 pm, Hylan 1106A We prove that a weak solution of a slightly supercritical fractional Burgers equation becomes H\"older continuous for large time. Tea served at 1:30pm, Math Lounge, Hylan Bldg., 9th floor.
	Topology Seminar Torsion and Open Book Decompositions. David Shea Vela-Vick,(Columbia University) 4 pm - 5 pm, Hylan 1106A Interpreting and understanding contact geometric notions in terms of open book decompositions has been a central theme in the study of contact structures on 3-manifolds ever since Giroux's fundamental breakthrough equating contact structures on a 3-manifold with open book decompositions up to positive stabilization. Concretely, one would like to understand how natural structures arising on contact manifolds are reflected in their supporting open book decompositions. Giroux torsion is a perfect example of such a structure as it is currently the only known mechanism for a manifold to admit more than a finite number of tight contact structures. In this talk, I will shop how to use new invariants of transverse links coming from Heegaard Floer homology to begin to study the relationship between Giroux torsion and open book decompositions. Tea will be served at 3:30PM in the common room on the 9th floor of Hylan
18 (Wednesday)	Special talk The First 150 Years of the Riemann Zeta-Function Steve Gonek 1 pm - 2 pm, CSB 209 Wednesday November 18, has been declared "Riemann Hypothesis Day" in celebration of the 150th anniversary of the publication of Riemann's famous paper on the zeta-function. That day there will be lectures all over the world on topics related to the zeta-function (see link). As our local contribution I will speak on "The First 150 Years of the Riemann Zeta-Function " In this survey talk I will describe the contents of Riemann's pivotal paper "Ueber die Anzahl der Primzahlen unter einer gegebenen Grosse" ("On the number of primes less than a given magnitude"), the early work it spurred in the theory of the zeta-function, and how the theory subsequently developed. Along the way we give an overview of key features of the theory and an idea of how some of the most important results were achieved.
20 (Friday)	Analysis Seminar Nonlinear elliptic equations at resonance Nsoki Mavinga, University of Rochester 2 pm - 3 pm, Hylan 1106A We consider a generalized Steklov-Robin eigenproblem with (singular) weights and prove existence results for nonlinear elliptic equations when the nonlinear perturbations are at resonance with the spectrum, in some sense. The proofs are based on variational methods, a priori estimates, and topological degree techniques.
	Probability/Math-Physics A resonance approach to evolution of entanglement Marco Merkli (MUN) 3 pm, Hylan 1106A We consider a system S = S_1 + S_2 of two spins 1/2 (qubits) interacting with several thermal reservoirs. Each spin j=1,2 is coupled to an individual reservoir R_j and the two spins interact collectively with a third reservoir R. All reservoirs are at the same temperature and do not interact directly. Each interaction between a spin and a reservoir has two channels, an energy-conserving and an energy-exchange one. We analyze decoherence, thermalization and disentanglement of the system S. We show that due to the energy-exchange interactions, the system has a finite disentanglement time, we estimate that time and compare it to decoherence times. Tea served at 3:00PM in math lounge, 9th floor Hylan Building.