Tue, 14 Jun 2016

15:45 - 16:45
L4

Symplectic homology for cobordisms

Alexandru Oancea
(Jussieu)
Abstract

I will present a definition of symplectic homology groups for pairs of Liouville cobordisms with fillings, and explain how these fit into a formalism of homology theory similar to that of Eilenberg and Steenrod. This construction allows to understand form a unified point of view many structural results involving Floer homology groups, and yields new applications. Joint work with Kai Cieliebak.

Tue, 31 May 2016

15:45 - 16:45
L4

Non-reductive GIT for graded groups and curve counting

Greg Berczi
(Oxford)
Abstract
I will start with a short report on recent progress in constructing quotients by actions of non-reductive algebraic groups and extending Mumford's geometric invariant theory to a wide class of non-reductive linear algebraic groups which we call graded groups. I will then explain how certain components of the Hilbert scheme of points on smooth varieties can be described as non-reductive quotients and why this description is especially efficient to study the topology of Hilbert schemes. In particular I will explain how equivariant localisation can be used to develop iterated residue formulae for tautological integrals on geometric subsets of Hilbert schemes and I present new formulae counting curves on surfaces (and more generally hypersurfaces in smooth varieties) with given singularity classes. This talk is based on joint works with Frances Kirwan, Thomas Hawes, Brent Doran and Andras Szenes. 
Thu, 05 May 2016

16:00 - 17:00
C5

Deligne’s construction for extending connections

Francis Bischoff
(University of Toronto)
Abstract

Let X be a complex manifold with divisor D. I will describe a construction, which is due to Deligne, whereby given a choice of a branch of the logarithm one can canonically extend a holomorphic flat connection on the complement of the divisor X\D to a flat logarithmic connection on X.

Frost heave is a common problem in any country where the temperature drops below 0 degrees Celsius. It’s most commonly known as the cause of potholes that form in roads during winter, costing billions of dollars worth of damage worldwide each year. However, despite this, it is still not well understood. For example, the commonly accepted explanation of how it occurs is that water expands as it freezes, and this expansion tears open the surrounding material.

Fri, 17 Jun 2016

10:00 - 11:00
L5

Reconstructing effective signalling networks in T cells

Omer Dushek
(Sir William Dunn School of Pathology)
Abstract

T cells are important white blood cells that continually circulate in the body in search of the molecular signatures ('antigens') of infection and cancer. We (and many other labs) are trying to construct models of the T cell signalling network that can be used to predict how ligand binding (at the surface of the cell) controls gene express (in the nucleus). To do this, we stimulate T cells with various ligands (input) and measure products of gene expression (output) and then try to determine which model must be invoked to explain the data. The challenge that we face is finding 1) unique models and 2) scaling the method to many different input and outputs.

Fri, 27 May 2016
10:00
L4

Mathematical models of genome replication

Conrad Nieduszynski
(Sir William Dunn School of Pathology)
Abstract

We aim to determine how cells faithfully complete genome replication. Accurate and complete genome replication is essential for all life. A single DNA replication error in a single cell division can give rise to a genomic disorder. However, almost all experimental data are ensemble; collected from millions of cells. We used a combination of high-resolution, genomic-wide DNA replication data, mathematical modelling and single cell experiments to demonstrate that ensemble data mask the significant heterogeneity present within a cell population; see [1-4]. Therefore, the pattern of replication origin usage and dynamics of genome replication in individual cells remains largely unknown. We are now developing cutting-edge single molecule methods and allied mathematical models to determine the dynamics of genome replication at the DNA sequence level in normal and perturbed human cells.

[1] de Moura et al., 2010, Nucleic Acids Research, 38: 5623-5633

[2] Retkute et al, 2011, PRL, 107:068103

[3] Retkute et al, 2012, PRE, 86:031916

[4] Hawkins et al., 2013, Cell Reports, 5:1132-41

Mon, 09 May 2016

12:00 - 13:00
L3

Mirror symmetry, supersymmetry and generalized geometry on SU(4)-structure vacua

Daniel Prins
(CEA/Saclay)
Abstract
Recently, there has been some progress in examining mirror symmetry beyond Calabi-Yau threefolds. I will discuss how this is related to flux vacua of type II supergravity on eight-dimensional manifolds equipped with SU(4)-structure. It will be shown that the natural framework to describe such vacua is generalized complex geometry. Two classes of type IIB solutions will be given, one of which is complex, the other symplectic, and I will describe in what sense these are mirror to one another.  
 
Tue, 10 May 2016

15:30 - 17:00
L4

Cohomological DT theory beyond the integrality conjecture

Ben Davison
(EPFL)
Abstract
The integrality conjecture is one of the central conjectures of the DT theory of quivers with potential, which itself is a key tool in understanding the local calculation of DT invariants on moduli spaces of coherent sheaves, as well as having deep links to geometric representation theory, noncommutative geometry and algebraic combinatorics.  I will explain some of the ingredients of the proof of this conjecture by myself and Sven Meinhardt.  In fact the proof gives much more than the original conjecture, which ultimately concerns identities in a Grothendieck ring of mixed Hodge structures associated to moduli spaces of representations, and proves that these equalities categorify to isomorphisms in the category of mixed Hodge structures.  I'll explain what this all means, as well as giving some applications of the categorified version of the theory.
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