Seminars and Colloquia by Series

Intuitive Dyadic Calculus

Series
Analysis Working Seminar
Time
Monday, November 10, 2014 - 15:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Robert Rahm – School of Math
We discuss an approach to dyadic lattices (and their applications to harmonic analysis) presented by Lerner and Nazarov in their manuscript, Intutive Dyadic Calculus.

Torsion of curves on locally convex surfaces

Series
Geometry Topology Seminar
Time
Monday, November 10, 2014 - 14:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Mohammad Ghomi – Georgia Tech –
We prove that the torsion of any smooth closed curve in Euclidean space which bounds a simply connected locally convex surface vanishes at least 4 times (vanishing of torsion means that the first 3 derivatives of the curve are linearly dependent). This answers a question of Rosenberg related to a problem of Yau on characterizing the boundary of positively curved disks in 3-space. Furthermore, our result generalizes the 4 vertex theorem of Sedykh for convex space curves, and thus constitutes a far reaching extension of the classical 4 vertex theorem for planar curves. The proof follows from an extensive study of the structure of convex caps in a locally convex surface.

Embeddings of manifolds and contact manifolds IV

Series
Geometry Topology Working Seminar
Time
Friday, November 7, 2014 - 14:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
John Etnyre – Georgia Tech
This is the fourth of several talks discussing embeddings of manifolds. I will discuss some general results for smooth manifolds, but focus on embeddings of contact manifolds into other contact manifolds. Particular attention will be paid to embeddings of contact 3-manifolds in contact 5-manifolds. I will discuss two approaches to this last problem that are being developed jointly with Yanki Lekili.

Frontiers in Science - Bionic Knees and Elephant Nerves

Series
Other Talks
Time
Thursday, November 6, 2014 - 19:00 for 2 hours
Location
Clary Theatre
Speaker
Max Donelan – Simon Fraser University, Department of Biomedical Physiology and Kinesiology

Please Note: 
After the talk there will be a reception and time for visitors to chat with Donelan and each other.

Professor Max Donelan talks about the bionic energy harvester, which uses energy generated from walking to power portable devices. He also discusses his research on the reflexes and nerves of animals, from elephants to shrews.

Singularity formation in Compressible Euler equations (Part II)

Series
PDE Working Seminar
Time
Thursday, November 6, 2014 - 15:00 for 1 hour (actually 50 minutes)
Location
Skiles 005
Speaker
Ronhua Pan – GeorgiaTech –
Compressible Euler equations describe the motion of compressible inviscid fluid. Physically, it states the basic conservation laws of mass, momentum, and energy. As one of the most important examples of nonlinear hyperbolic conservation laws, it is well-known that singularity will form in the solutions of Compressible Euler equations even with small smooth initial data. This talk will discuss some classical results in this direction, including some most recent results for the problem with large initial data.

Mixing rates of interacting particle systems

Series
Math Physics Seminar
Time
Thursday, November 6, 2014 - 14:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Yao Li – Courrant Institute, NY –
In this talk I will begin with our recent results on non-equilibrium steady states (NESS) of a microscopic heat conduction model, which is a stochastic particle system coupled to unequal heat baths. This stochastic model is derived from a mechanical chain model (Eckmann and Young 2006) by randomizing certain quantities while retaining the other features. We proved various results including the existence and uniqueness of NESS and the exponential rate of mixing. Then I will follow with an energy dependent Kac-type model that is obtained from an improved version of randomization of the “local" dynamics. We rigorously proved that this Kac-type model has a mixing rate $\sim t^{-2}$. In the end, I will show that slow (polynomial) mixing rates appear in a large class of statistical mechanics models.

Revisiting classical results at the interface of number theory and representation theory

Series
School of Mathematics Colloquium
Time
Thursday, November 6, 2014 - 11:00 for 1 hour (actually 50 minutes)
Location
Skiles 005
Speaker
Ken Ono – Emory University
The speaker will discuss recent work on Moonshine and the Rogers-Ramanujan identities. The Rogers-Ramanujan identities are two peculiar identities which express two infinite product modular forms as number theoretic q-series. These identities give rise to the Rogers-Ramanujan continued fraction, whose values at CM points are algebraic integral units. In recent work with Griffin and Warnaar, the speaker has obtained a comprehensive framework of identities for infinite product modular forms in terms of Hall-Littlewood q-series. This work characterizes those integral units that arise from this theory. In a related direction, the speaker revisits the classical Moonshine Theorem which asserts that the coefficients of the modular j-functions are dimensions of virtual characters for the Monster, the largest of the simple sporadic groups. There are 194 irreducible representations of the Monster, and it has been a longstanding open problem to determine the distribution of these representations in Moonshine. In joint work with Griffin and Duncan, the speaker has obtained exact formulas for these distributions.

The Thurston Norm

Series
Geometry Topology Student Seminar
Time
Wednesday, November 5, 2014 - 14:05 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Shane Scott – GaTech
The genus of a knot can be thought of as a measure of complexity for a 3 dimensional knot compliment. This notion can be extended to compact 3 manifolds by defining a norm on the second homology group with real coefficients measuring the Euler characteristic of embedded surfaces.

Joint Athens-Atlanta Number Theory

Series
Algebra Seminar
Time
Tuesday, November 4, 2014 - 16:00 for 4 hours (half day)
Location
Skiles 005
Speaker
Arul Shankar and Wei Zhang – Harvard University and Columbia University
The Joint Athens-Atlanta Number Theory Seminar meets once a semester, usually on a Tuesday, with two talks back to back, at 4:00 and at 5:15. Participants then go to dinner together.

Shock wave solutions of conservation laws and their regularization by dissipation and dispersion.

Series
PDE Seminar
Time
Tuesday, November 4, 2014 - 15:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Michael Shearer – North Carolina State University
Shock waves are idealizations of steep spatial gradients of physical quantities such as pressure and density in a gas, or stress in an elastic solid. In this talk, I outline the mathematics of shock waves for nonlinear partial differential equations that are simple models of physical systems. I will focus on non-classical shocks and smooth waves that they approximate. Of particular interest are comparisons between nonlinear traveling waves influenced strongly by dissipative effects such as viscosity or surface tension, and spreading waves generated by the balance between dispersion and nonlinearity, when the nonlinearity is non-convex.

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