Mon, 30 Apr 2007
12:00
L3

D-brane superpotentials and RG flows on the quintic

Ilka Brunner
(ETH Zurich)
Abstract
    The behaviour of D2-branes on the quintic under complex structure deformations is analysed by combining Landau-Ginzburg techniques with methods from conformal field theory. It is shown that the boundary renormalisation group flow induced by the bulk deformations is realised as a gradient flow of the effective space time superpotential which is calculated explicitly to all orders in the boundary coupling constant.
Fri, 27 Apr 2007
11:45
DH 3rd floor SR

Waxy Oils

Lorenzo Fusi
(Dept. of Ulisse Dini, Florence)
Thu, 26 Apr 2007
16:30
DH 1st floor SR

Biological applications of reaction diffusion equations and low Reynolds number fluid dynamics

Eamonn Gaffney
(Oxford)
Abstract
 

Aspects of my current research will be reviewed. In terms of reaction diffusion equations, I will review current work on cancer modelling and biological pattern formation. I will then proceed to consider biological applications of low Reynolds number fluid dynamics with respect to cilia-induced flows in the lung and human spermatozoa dynamics.  

 
Thu, 26 Apr 2007

14:00 - 15:00
Rutherford Appleton Laboratory, nr Didcot

Multigrid solvers for quantum dynamics - a first look

Dr Scott McLachlan
(Delft University of Technology)
Abstract

The numerical study of lattice quantum chromodynamics (QCD) is an attempt to extract predictions about the world around us from the standard model of physics. Worldwide, there are several large collaborations on lattice QCD methods, with terascale computing power dedicated to these problems. Central to the computation in lattice QCD is the inversion of a series of fermion matrices, representing the interaction of quarks on a four-dimensional space-time lattice. In practical computation, this inversion may be approximated based on the solution of a set of linear systems.

In this talk, I will present a basic description of the linear algebra problems in lattice QCD and why we believe that multigrid methods are well-suited to effectively solving them. While multigrid methods are known to be efficient solution techniques for many operators, those arising in lattice QCD offer new challenges, not easily handled by classical multigrid and algebraic multigrid approaches. The role of adaptive multigrid techniques in addressing the fermion matrices will be highlighted, along with preliminary results for several model problems.

Mon, 23 Apr 2007
15:45
DH 3rd floor SR

SPDE's driven by Poissonian noise

Dr Erika Hausenblas
Abstract
 

First I will introduce Poisson random measures and their connection to Levy processes.  Then SPDE

Fri, 20 Apr 2007
15:15
L3

Garside's Solution to the Conjugacy Problem in the Braid Group

Tristram de Piro
(Camerino)
Abstract
  I will discuss Garside's representation of elements of the braid group in terms of "half- twists" and the corresponding solution to the Conjugacy Problem, originally posed by Artin. If time permits, I will discuss some geometric implications of this result.  
Wed, 28 Mar 2007
15:00
L3

Blurred exponentiation and the geometry of exponential fields

Jonathan Kirby
(UIC, Chicago)
Abstract
  I will discuss the proof that the exponential algebraic closure operator on the complex exponential field is isomorphic to the pregeometry which controls the "pseudoexponential" field.  
Wed, 28 Mar 2007
11:00
L3

From Polynomial Interpolation to the Complexity of Ideals

David Eisenbud, MSRI
(Berkeley)
Abstract

 

 

One natural question in interpolation theory is: given a finite set of points

in R^n, what is the least degree of polynomials on R^n needed to induce every

function from the points to R? It turns out that this "interpolation degree" is

closely related to a fundamental measure of complexity in algebraic geometry

called Castelnuovo-Mumford regularity. I'll explain these ideas a new

application to projections of varieties.

 

Mon, 26 Mar 2007
15:45
DH 3rd floor SR

From Ising 2D towards Mumford-Shah (joint work with Reda Messikh)

Professor Raphael Cerf
(Universite de Paris XI)
Abstract
  The talk will be self-contained and does not require specific knowledge on the Ising model. I will present the basic results concerning the Wulff crystal of the Ising model and I will study its behaviour near the critical point. Finally I will show how to apply these results to the problem of image segmentation.