14:30
Random plane waves and other classes of random functions
Abstract
There are several classes of random function that appear naturally in mathematical physics, probability, number theory, and other areas of mathematics. I will give a brief overview of some of these random functions and explain what they are and why they are important. Finally, I will explain how I use chebfun to study these functions.
Octupolar Order Tensors
Abstract
In Soft Matter, octupolar order is not just an exotic mathematical curio. Liquid crystals have already provided a noticeable case of soft ordered materials for which a (second-rank) quadrupolar order tensor may not suffice to capture the complexity of the condensed phases they can exhibit. This lecture will discuss the properties of a third-rank order tensor capable of describing these more complex phases. In particular, it will be shown that octupolar order tensors come in two separate, equally abundant variants. This fact, which will be given a simple geometric interpretation, anticipates the possible existence of two distinct octupolar sub-phases.
On the Ihara/Oda-Matsumoto conjecture and its variants
Abstract
Following the spirit of Grothendieck’s Esquisse d’un Programme, the Ihara/Oda-Matsumoto conjecture predicted a combinatorial description of the absolute Galois group of Q based on its action on geometric fundamental groups of varieties. This conjecture was resolved in the 90’s by Pop using anabelian techniques. In this talk, I will discuss some satronger variants of this conjecture, focusing on the more recent solutions of its pro-ell and mod-ell two-step nilpotent variants.
14:15
Two phase flow in volcanic conduits
Abstract
Strombolian volcanoes are thought to maintain their semi-permanent eruptive style by means of counter-current two-phase convective flow in the volcanic conduit leading from the magma chamber, driven by the buoyancy provided by exsolution of volatiles such as water vapour and carbon dioxide in the upwelling magma, due to pressure release. A model of bubbly two-phase flow is presented to describe this, but it is found that the solution breaks down before the vent at the surface is reached. We propose that the mathematical breakdown of the solution is associated with the physical breakdown of the two-phase flow regime from a bubbly flow to a churn-turbulent flow. We provide a second two-phase flow model to describe this regime, and we show that the solution can be realistically continued to the vent. The model is also in keeping with observations of eruptive style.
Oxford Mathematician and Fellow of Keble College, Gui-Qiang G. Chen has been elected a Fellow of the American Mathematical Society in recognition of his contribution to partial differential equations, nonlinear analysis, fluid mechanics, hyperbolic conservation laws, and shock wave theory.
11:00
10:00
Realising the projective representations of the symmetric group using Dirac cohomology.
Abstract
Firstly I will outline Dirac cohomology for graded Hecke algebras and the branching rules for the projective representations of $S_n$. Combining these notions with the Jucys-Murphy elements for $\tilde{S}_n$, that is the double cover of the symmetric group, I will go through a method to completely describe the spectrum data for the Jucys-Murphy elements for $\tilde{S}_n$. If time allows I will also explain how this spectrum data gives rise to a a concrete description for the matrices of the action of $\tilde{S}_n$.