Forthcoming Seminars
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Thu, 07/05/2009 15:45 |
Eduard Looijenga (Utrecht) |
Algebraic and Symplectic Geometry Seminar  |
SR1 |
| This is an overview, mostly of work of others (Denef, Loeser, Merle, Heinloth-Bittner,..). In the first part of the talk we give a brief introduction to motivic integration emphasizing its application to vanishing cycles. In the second part we discuss a join construction and formulate the relevant Sebastiani-Thom theorem. | |||
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Thu, 07/05/2009 16:00 |
Tom Ward (East Anglia) |
Number Theory Seminar |
L3 |
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Thu, 07/05/2009 16:30 |
Stephen Peppin (OCCAM (Oxford)) |
Differential Equations and Applications Seminar |
DH 1st floor SR |
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Thu, 07/05/2009 17:00 |
Dugald McPherson (Leeds) |
Logic Seminar |
L3 |
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Fri, 08/05/2009 10:00 |
Alexander Korsunsky (Department of Engineering Science, University of Oxford) |
Industrial and Interdisciplinary Workshops |
DH 1st floor SR |
| Inverse problems arise with regularity (sic!) in the context of our study of the deformation of solids, and its characterisation (in terms of diffraction and imaging) using radiation (neutrons and X-rays). I wish to introduce several examples where the advancement of inverse problem methods can make a significant impact on applicatins. 1. Inverse eigenstrain analysis of residual stress states 2. Strain tomography 3. Strain image correlation Depending on the time available, I may also mention (a) Rietveld refinement of diffraction patterns from polycrystalline aggregates, and (b) Laue pattern indexing and energy dispersive detection for single grain strain analysis. | |||
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Fri, 08/05/2009 14:15 |
Jean-Paul Decamps (Toulouse) |
Nomura Seminar |
DH 1st floor SR |
| We focus on structural models in corporate finance with roll-over debt structure and endogenous default triggered by limited liability equity-holders. We point out imprecisions and misstatements in the literature and provide a rationale for the endogenous default policy. | |||
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Fri, 08/05/2009 14:30 |
Dr. Jim McElwaine (University of Cambridge.) |
Mathematical Geoscience Seminar |
DH 3rd floor SR |
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Fri, 08/05/2009 16:30 |
Thomas Woolley (University of Oxford) |
Junior Applied Mathematics Seminar |
DH 3rd floor SR |
| Soliton like structures called “stable droplets” are found to exist within a paradigm reaction diffusion model which can be used to describe the patterning in a number of fish species. It is straightforward to analyse this phenomenon in the case when two non-zero stable steady states are symmetric, however the asymmetric case is more challenging. We use a recently developed perturbation technique to investigate the weakly asymmetric case. | |||
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Fri, 08/05/2009 16:30 |
Professor Steven N. Evans (University of California) |
Colloquia |
L2 |
| A common question in evolutionary biology is whether evolutionary processes leave some sort of signature in the shape of the phylogenetic tree of a collection of present day species. Similarly, computer scientists wonder if the current structure of a network that has grown over time reveals something about the dynamics of that growth. Motivated by such questions, it is natural to seek to construct“statistics” that somehow summarise the shape of trees and more general graphs, and to determine the behaviour of these quantities when the graphs are generated by specific mechanisms. The eigenvalues of the adjacency and Laplacian matrices of a graph are obvious candidates for such descriptors. I will discuss how relatively simple techniques from linear algebra and probability may be used to understand the eigenvalues of a very broad class of large random trees. These methods differ from those that have been used thusfar to study other classes of large random matrices such as those appearing in compact Lie groups, operator algebras, physics, number theory, and communications engineering. This is joint work with Shankar Bhamidi (U. of British Columbia) and Arnab Sen (U.C. Berkeley). | |||
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Mon, 11/05/2009 12:00 |
David Skinner (Oxford) |
String Theory Seminar |
L3 |
| Abstract: Modern techniques for computing multi-particle and multi-loop scattering amplitudes rely on a sophisticated use of on-shell recursion relations and generalised unitarity methods. I will show that these methods are ideally suited to interpretation in twistor space, where superconformal properties become manifest. In fact, the recursion relations of Britto, Cachazo, Feng & Witten provide a clear framework for the twistor diagram program initiated in the 1970s. Tree-level scattering amplitudes in N=4 SYM are now known to possess a Yangian symmetry, formed by combining the original PSU(2,2|4) superconformal invariance with a second "dual" copy. I will also discuss very recent work constructing scattering amplitudes in a twistor space in which this dual superconformal symmetry acts geometrically. | |||
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Mon, 11/05/2009 14:15 |
Dr Martin Pistorius |
Stochastic Analysis Seminar |
Oxford-Man Institute |
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Mon, 11/05/2009 14:15 |
Peter Zograf (St Petersburg) |
Geometry and Analysis Seminar |
L3 |
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Mon, 11/05/2009 15:45 |
Dr Ismael Bailleul (Cambridge) |
Stochastic Analysis Seminar |
Oxford-Man Institute |
| A new class of relativistic diffusions encompassing all the previously studied examples has recently been introduced by C. Chevalier and F Debbasch, both in a heuristic and analytic way. Roughly speaking, they are characterised by the existence at each (proper) time (of the moving particle) of a (local) rest frame where the random part of the acceleration of the particle (computed using the time of the rest frame) is brownian in any spacelike direction of the frame. I will explain how the tools of stochastic calculus enable us to give a concise and elegant description of these random paths on any Lorentzian manifiold. A mathematically clear definition of the the one-particle distribution function of the dynamics will emerge from this definition, and whose main property will be explained. This will enable me to obtain a general H-theorem and to shed some light on links between probablistic notions and the large scale structure of the manifold. All necessary tools from stochastic calculus and geometry will be explained. | |||
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Mon, 11/05/2009 15:45 |
Stefan Schwede (Bonn) |
Topology Seminar |
L3 |
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Mon, 11/05/2009 17:00 |
Jian-Guo Liu (College Park, Maryland) |
Partial Differential Equations Seminar |
Gibson 1st Floor SR |
| For incompressible Navier-Stokes equations in a bounded domain, I will first present a formula for the pressure that involves the commutator of the Laplacian and Leray-Helmholtz projection operators. This commutator and hence the pressure is strictly dominated by the viscous term at leading order. This leads to a well-posed and computationally congenial unconstrained formulation for the Navier-Stokes equations. Based on this pressure formulation, we will present a new understanding and design principle for third-order stable projection methods. Finally, we will discuss the delicate inf-sup stability issue for these classes of methods. This is joint work with Bob Pego and Jie Liu. | |||
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Tue, 12/05/2009 12:00 |
Richard Jozsa (Bristol) |
Quantum Field Theory Seminar |
L3 |
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Tue, 12/05/2009 14:30 |
Mihyun Kang (TU Berlin) (TU Berlin) |
Combinatorial Theory Seminar |
L3 |
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Tue, 12/05/2009 15:45 |
Eckhard Platen (UTS) |
Nomura Seminar |
Oxford-Man Institute |
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Tue, 12/05/2009 15:45 |
Sven Meinhardt (Oxford) |
Algebraic and Symplectic Geometry Seminar |
L3 |
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Tue, 12/05/2009 16:30 |
Dr Laure Zanna (University of Oxford) |
Geophysical and Nonlinear Fluid Dynamics Seminar |
Dobson Room, AOPP |
