Seminars and Colloquia by Series

Stability and bifurcation in a reaction–diffusion model with nonlocal delay effect

Series
CDSNS Colloquium
Time
Monday, August 17, 2015 - 23:00 for 1 hour (actually 50 minutes)
Location
Skiles 005
Speaker
Shangjiang GuoCollege of Mathematics and Econometrics, Hunan University
In this talk, the existence, stability, and multiplicity of spatially nonhomogeneous steady-state solution and periodic solutions for a reaction–diffusion model with nonlocal delay effect and Dirichlet boundary condition are investigated by using Lyapunov–Schmidt reduction. Moreover, we illustrate our general results by applications to models with a single delay and one-dimensional spatial domain.

Existence and multiplicity of wave trains in 2D lattices

Series
CDSNS Colloquium
Time
Monday, August 10, 2015 - 11:00 for 1 hour (actually 50 minutes)
Location
Skiles 005
Speaker
Shangjiang GuoCollege of Mathematics and Econometrics, Hunan University
We study the existence and branching patterns of wave trains in a two-dimensional lattice with linear and nonlinear coupling between nearest particles and a nonlinear substrate potential. The wave train equation of the corresponding discrete nonlinear equation is formulated as an advanced-delay differential equation which is reduced by a Lyapunov-Schmidt reduction to a finite-dimensional bifurcation equation with certain symmetries and an inherited Hamiltonian structure. By means of invariant theory and singularity theory, we obtain the small amplitude solutions in the Hamiltonian system near equilibria in non-resonance and $p:q$ resonance, respectively. We show the impact of the direction $\theta$ of propagation and obtain the existence and branching patterns of wave trains in a one-dimensional lattice by investigating the existence of travelling waves of the original two-dimensional lattice in the direction $\theta$ of propagation satisfying $\tan\theta$ is rational

Sum-product Inequalities and Combinatorial Problems on Sumsets

Series
Dissertation Defense
Time
Friday, July 17, 2015 - 14:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Albert BushSchool of Mathematics, Georgia Tech
The thesis investigates a version of the sum-product inequality studied by Chang in which one tries to prove the h-fold sumset is large under the assumption that the 2-fold product set is small. Previous bounds were logarithmic in the exponent, and we prove the first super-logarithmic bound. We will also discuss a new technique inspired by convex geometry to find an order-preserving Freiman 2-isomorphism between a set with small doubling and a small interval. Time permitting, we will discuss some combinatorial applications of this result.

Automorphism Groups of Surface Cluster Algebras

Series
Geometry Topology Student Seminar
Time
Thursday, July 16, 2015 - 14:05 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Shane ScottGeorgia Tech
This talk is an oral comprehensive exam in partial fulfillment of the requirements for a doctoral degree. To any topological surface we can assign a certain communtative algebra called a cluster algebra. A surface cluster algebra naturally records the geometry of the surface. The algebra is generated by arcs of the surface. Arcs carry a simplicial structure where the maximal simplices are triangulations. If you squint you can view a surface cluster algebra as a coordinate ring of decorated Teichmuller space with Penner's coordinate. Recent work from many authors has shown that the automorphisms of the surface cluster algebra which preserve triangulations arise from the mapping class group of the surface. But there are additional automorphisms that preserve meaningful structure of the cluster algebra. In this talk we will define surface cluster algebras and discuss future research toward understanding structure preserving automorphisms.

MCTP REU Seminar

Series
Other Talks
Time
Friday, July 10, 2015 - 12:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Dr. Josephine YuGeorgia Institute of Technology
TBA

MCTP REU Seminar: Elevating Deceptions: A Mathemagical Mystery Tour

Series
Other Talks
Time
Friday, June 26, 2015 - 11:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Dr. Matt BakerGeorgia Institute of Technology
Science explains through systematic inquiry; magic celebrates that which defies explanation. This will be tour of sorts along the boundary between science and magic. We will explore the magic of quantum mechanics, the predictions of knot theory, and randomness, as well as the mysteries of the number 58008.

Analytic Continuation of Analytic Fractals

Series
Analysis Seminar
Time
Wednesday, June 24, 2015 - 15:00 for 1 hour (actually 50 minutes)
Location
Skiles 005
Speaker
Michael BarnsleyMathematical Sciences Institute, Australian National University
Examples of analytic fractals are Julia sets, Koch Curves, and Sierpinski triangles, and graphs of analytic functions. Given a piece of such a set, how does one "continue" it, in a manner consistent with the classical construction of an analytic Riemannian manifold, starting from a locally convergent series expansion?

MCTP REU Seminar -Reaction Diffusion Equations and Pattern Formation in Mathematical Biology (How the Zebra got his/her stripes)

Series
Other Talks
Time
Monday, June 22, 2015 - 12:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Dr. James MooreGeorgia Institute of Technology
Reaction diffusion equations are a common tool in mathematical biology, and are used in diverse fields such as ecology, epidemiology and developmental biologyI will show some examples of reaction diffusion equations and what their solutions look like. I will focus on the problem of pattern formation during development and the mathematics that underly it, a problem first studied by Alan Turing more than 60 years ago. I will present a basic example that we can solve together using techniques from differential equations and linear algebra.

MCTP REU Seminar: Riddles about the fundamental group

Series
Other Talks
Time
Friday, June 19, 2015 - 11:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Dr. Kirsten WickelgrenGeorgia Tech
The loops on a topological space up to an equivalence relation called homotopy form a group called the fundamental group. We'll define the fundamental group and talk about two riddles whose solutions use this idea.

On the marginals of product measures

Series
Stochastics Seminar
Time
Monday, June 15, 2015 - 14:00 for 1 hour (actually 50 minutes)
Location
Skiles 005
Speaker
Galyna LivshytsKent State University
It was shown by Keith Ball that the maximal section of an n-dimensional cube is \sqrt{2}. We show the analogous sharp bound for a maximal marginal of a product measure with bounded density. We also show an optimal bound for all k-codimensional marginals in this setting, conjectured by Rudelson and Vershynin. This talk is based on the joint work with G. Paouris and P. Pivovarov.

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