Rennes / PIMS

Mon 23 Jan 2017, 3:00pm
Algebraic Geometry Seminar
MATX 1102

On Grothendieck rings in real geometry

MATX 1102
Mon 23 Jan 2017, 3:00pm4:00pm
Abstract
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Toronto

Mon 23 Jan 2017, 3:00pm
SPECIAL
Institute of Applied Mathematics
ESB 2012

Matrix regulation of stem cell fate

ESB 2012
Mon 23 Jan 2017, 3:00pm4:00pm
Abstract
Stem cell fate is regulated by cues from the cellular microenvironment, including biophysical and biochemical cues presented by the extracellular matrix. Matrix regulation of cell fate has broad implications from disease to regeneration. In this talk, I will discuss our work aimed at determining how biophysical and biochemical cues from the matrix act to drive the fate and function of mesenchymal stem cells. In particular, I will discuss how the pathological differentiation of heart valve progenitor cells is modulated by the extracellular matrix and how we are using microdevices to dissect how matrix mechanical and biochemical cues act in concert to regulate mesenchymal stem cell differentiation and tissue regeneration.
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Max Planck Institute Bonn

Tue 24 Jan 2017, 3:00pm
SPECIAL
Diff. Geom, Math. Phys., PDE Seminar
MATH 126

Chiral differential operators and the curved betagamma system

MATH 126
Tue 24 Jan 2017, 3:00pm4:00pm
Abstract
Chiral differential operators (CDOs) are a vertex algebra analog of the associative algebra of differential operators. Originally introduced by mathematicians, Witten explained how CDOs arise as the perturbative part of the curved betagamma system with target X. I will describe recent work with Gorbounov and Williams in which we construct the BV quantization of this theory and use a combination of factorization algebras and formal geometry to recover CDOs. At the end, I hope to discuss how the techniques we developed apply to a broad class of nonlinear sigma models, including source manifolds of higher dimension.
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Center for Geometry and Physics/ Pohang Univ. of Sci. and Tech. Korea.

Tue 24 Jan 2017, 4:00pm
SPECIAL
MATH 1102 Topology/Algebra/Math Physics seminar

A quantization of the unipotent fundamental group

MATH 1102 Topology/Algebra/Math Physics seminar
Tue 24 Jan 2017, 4:00pm5:00pm
Details
We construct two homotopy functors from the category of homotopy commutative algebras to the category of prounipotent group and the category of completed commutative Hopf algebras such that
(1) the group is isomorphic to the pro unipotent fundamental group of smooth connected and based manifold (M,*) and
(2) the Hopf algebra is that of homotopy functionals defined by Chen’s iterated path integrals over closed and based loops on M
if the homotopy commutative algebra is quasiisomorphic to the algebra of differential forms on M.
These constructions can be quantized in appropriate sense after interpreting them as doing “classical field theory” such that the pro unipotent fundamental group is the structure in the space of all "classical expectations" and the completed Hopf algebra is the algebra of “classical observables”. The quantization involves a generalized deformation quantization of homotopy commutative algebra into topologically free homotopy associative algebra along the direction of compatible homotopy Lie algebra.
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UBC

Wed 25 Jan 2017, 1:45pm
Mathematical Biology Seminar
PIMS, ESB 4th floor

Multiscale modeling of vesicular release at neuronal synapses.

PIMS, ESB 4th floor
Wed 25 Jan 2017, 1:45pm2:45pm
Abstract
Binding of molecules, ions or proteins to small target sites is a generic step of cell activation. This process relies on rare stochastic events where a particle located in a large bulk has to find small and often hidden targets. I will present in this talk a hybrid discretecontinuum model that takes into account both a stochastic regime governed by rare events and a continuous regime in the bulk, in the context of vesicular release at chemical synapses.
In a first part, I computed the mean time for a Brownian particle to arrive at a narrow opening defined as the small cylinder joining two tangent spheres. This models the binding of calcium ions on the SNARE complex, a process that triggers vesicular release. Using this result, I developed a model to study how vesicles and calcium channels organization shape such process.
In a second part, I will present a model for the presynaptic terminal built using the results described above. This model was formulated in an initial stage as a reactiondiffusion problem in a confined microdomain, where Brownian particles have to bind to small target sites. I coarsegrained this model into a system of mass action equations coupled to a set of Markov equations, which allows to obtain analytical results and to realize fast stochastic simulations.
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Max Planck Institute Bonn

Wed 25 Jan 2017, 3:00pm
SPECIAL
Department Colloquium
ESB 2012 (note special day)

From Feynman diagrams to commutative diagrams

ESB 2012 (note special day)
Wed 25 Jan 2017, 3:00pm4:00pm
Abstract
Factorization algebras are localtoglobal objects that play a role in quantum field theory akin to the role of sheaves in geometry: they conveniently organize complicated information. In the talk I will introduce this notion, give some concrete examples, and then explain how factorization algebras mediate between QFT and higher algebra. An important example will be ChernSimons theory; ongoing work with Costello and Francis recovers quantum groups with formal parameter by combining Koszul duality with Feynman diagrams.
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University of Chicago

Wed 25 Jan 2017, 4:15pm
SPECIAL
Topology and related seminars
ESB 4133 (PIMS Lounge)

Quantitative Nullcobordism and the (in)effectiveness of algebraic topology.

ESB 4133 (PIMS Lounge)
Wed 25 Jan 2017, 4:15pm5:15pm
Abstract
Topology is full of ineffective arguments constructing objects and equivalences by algebra.
One of the great early achievements of algebraic topology was the work of Thom, followed by Milnor and Wall, on cobordism theory, which describes when a compact smooth (oriented) manifold is the boundary of some compact manifold with boundary. This method is typical of the problems that arise in the use of algebraic methods and is an early example of one of the dominant philosophies of geometric topology. The question we study is to what extent the complexity of a manifold can be used to bound, when it exists, the minimum necessary complexity of something that it bounds.
The goal of this talk is to explain generally some of the issues of making topology less ineffective.
We shall show that there are polynomial size nullcobordisms in a suitable sense. This is joint work with Greg Chambers, Dominic Dotterer and Fedor Manin.
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University of Texas at Austin

Thu 26 Jan 2017, 3:00pm
SPECIAL
Diff. Geom, Math. Phys., PDE Seminar
TBD

TBA

TBD
Thu 26 Jan 2017, 3:00pm4:00pm
Abstract
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University of Texas at Austin

Fri 27 Jan 2017, 3:00pm
Department Colloquium
ESB 2012

TBA

ESB 2012
Fri 27 Jan 2017, 3:00pm4:00pm
Abstract
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Note for Attendees
Reception preceding the talk in ESB 4133 (the PIMS lounge). This is part of the IAM/PIMS distinguished colloquium series.