Weekly bulletin

Week starting Monday 26 February 2018

Monday 26 February - Computational Mathematics Seminar

Start time: 4pm

John Dedman Building 27 Room G35

Presenter(s): Assoc. Prof. Conrad Burden (MSI)

Population genetics models are usually based on the Wright-Fisher model, in which each individual in a population randomly chooses their parent from the previous generation.  One could argue that a more realistic description of population dynamics is a Galton-Watson branching process, in which each individual in a population produces a random number of offspring to create the next generation.  

In this talk I will describe a multi-type branching process, in which the population is divided into a finite number of allele types.  At each generation individuals are able to mutate to a different type.  By considering the the diffusion limit forward Kolmogorov equation for the case of neutral mutations we find that the population asymptotically partitions into subpopulations whose relative sizes are determined by mutation rates. An approximate time-dependent solution is obtained in the limit of low mutation rates. This solution has the property that the system undergoes a rapid transition from a perturbation of the model with zero mutation rates to a phase in which the distribution collapses onto the asymptotic stationary distribution. The changeover point of the transition is determined by the per-generation growth factor and mutation rate.  

Tuesday 27 February - Graduate Seminar

Start time: 11am

John Dedman Building 27 Room G35

Presenter(s): Dominic Weiller (MSI)

The PhD seminar is a weekly seminar held on Tuesday mornings, at 11am, for PhD students to talk about their thesis work or other projects.

There is tea in the common room afterwards.

Tuesday 27 February - Algebra and Topology Seminar

Start time: 3.30pm

John Dedman Building 27, Room G35.

Presenter(s): Jack Davies

Given a ring R and a multiplicative subset S of R, then one can localise R at S using a number of different constructions. Using some of these constructions it is not clear the result is flat over R, or non-zero, or even a ring. Commutative algebra tells us there is nothing to worry about in this situation, but as soon as we step into non-commutative algebra we require some type of Ore condition. 

We are going to take a step in another direction, towards equivariant homotopical algebra, and see that in the world of equivariant ring spectra, there is a necessary and sufficient condition to localise a ring sensibly. This follows work by Hill and Hopkins, and can sometimes be phrased in the global homotopy theory language of Schwede.

Updated:  22 February 2018/Responsible Officer:  Director/Page Contact:  School Manager