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 Events
Tel Aviv University
Mon 21 Sep 2020, 8:00am
Algebraic Groups and Related Structures
Online: link available at https://researchseminars.org/ or from Zinovy Reichstein
Galois cohomology of real reductive groups
Online: link available at https://researchseminars.org/ or from Zinovy Reichstein
Mon 21 Sep 2020, 8:00am-9:00am

Abstract

Using ideas of Kac and Vinberg, we give a simple combinatorial method of computing the Galois cohomology of semisimple groups over the field R of real numbers. I will explain the method by the examples of simple groups of type E_7 (both adjoint and simply connected). This is joint work with Dmitry A. Timashev, Moscow. Preprint available at  http://arxiv.org/abs/2008.11763
 
 
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Geoff Schiebinger
Department of Mathematics, UBC
Mon 21 Sep 2020, 3:00pm
Institute of Applied Mathematics
Zoom meeting
Towards a mathematical theory of developmental biology: Analyzing developmental processes with optimal transport
Zoom meeting
Mon 21 Sep 2020, 3:00pm-4:00pm

Abstract

 https://ubc.zoom.us/j/63318122194?pwd=RUV2RVZVZUtxV0FvdWhOaDBJbzVrQT09
Meeting ID: 633 1812 2194
Passcode: 141447
 
Abstract. This talk focuses on estimating temporal couplings of stochastic processes with optimal transport (OT), motivated by applications in developmental biology and cellular reprogramming. For nearly a century, the prevailing mathematical theory of developmental biology has been based on Waddington's `epigenetic landscape’ – a potential energy surface that determines trajectories of cellular development. Now, with the advent of high-throughput measurement technologies like single cell RNA-sequencing (scRNA-seq), the prospect of charting this landscape is within reach. This holds tremendous potential for diverse applications from regenerative medicine (e.g. cellular reprogramming) to agriculture (e.g. predicting impacts of climate change on crops or growing artificial meat). While the problem of recovering the landscape is inherently nonconvex, we demonstrate that the ‘laws on paths’ induced by this potential energy surface can be recovered using convex optimization. Our approach provides a general framework for investigating cellular differentiation.
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Northwestern University
Wed 23 Sep 2020, 2:05pm
Mathematical Biology Seminar
Zoom - contact organizer (abuttens at math ubc ca) for meeting id
Modeling and measuring cell dynamics in zebrafish-skin patterns
Zoom - contact organizer (abuttens at math ubc ca) for meeting id
Wed 23 Sep 2020, 2:05pm-3:05pm

Abstract

Wild-type zebrafish (Danio rerio) are characterized by black and yellow stripes, which form on their body and fins due to the self-organization of thousands of pigment cells. Mutant zebrafish and sibling species in the Danio genus, on the other hand, feature altered, variable patterns, including spots and labyrinth curves. The longterm goal of my work is to better link genotype, cell behavior, and phenotype by helping to identify the specific alterations to cell interactions that lead to these different fish patterns. Using a phenomenological approach, we develop agent-based models for cell interactions and simulate pattern formation on growing domains. In this talk, I will overview our models and highlight some topological techniques that allow us to quantitatively compare our simulations to in vivo images. I will also discuss current directions and open questions related to taking a more mechanistic and quantitative approach to describing cell behavior in zebrafish.

Note for Attendees

 Dr. Volkening will also deliver the Rising Stars colloquium on Oct 30, 2020.
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UBC and Technion
Wed 23 Sep 2020, 3:00pm
Probability Seminar
https://ubc.zoom.us/s/67941158154?pwd=TDRjdm1ta2Fxbi9tVjJyaWdKb3A5QT09
Scaling limits of uniform spanning trees in three dimensions
https://ubc.zoom.us/s/67941158154?pwd=TDRjdm1ta2Fxbi9tVjJyaWdKb3A5QT09
Wed 23 Sep 2020, 3:00pm-4:30pm

Abstract

Wilson's algorithm allows efficient sampling of the uniform spanning tree (UST) by using loop-erased random walks. This connection gives a tractable method to study the UST. The strategy has been fruitful for scaling limits of the UST in the planar case and high dimensions. However, three-dimensional scaling limits are far from understood. This talk is about recent advances in this problem when we describe the UST as a metric measure space. Our main result is on the existence of sub-sequential scaling limits and convergence under dyadic scalings with respect to a Gromov-Hausdorff-type topology. We will also discuss some properties of the limit tree.

This is joint work with Omer Angel, David Croydon, and Daisuke Shiraishi.
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University of Washington
Tue 29 Sep 2020, 4:00pm
Discrete Math Seminar
https://ubc.zoom.us/j/62676242229?pwd=RURtUC9UYXEweVZTMTNGT1EvY1FLZz09
Flexible Sunflowers of Convex Open Sets and Applications to Neural Codes
https://ubc.zoom.us/j/62676242229?pwd=RURtUC9UYXEweVZTMTNGT1EvY1FLZz09
Tue 29 Sep 2020, 4:00pm-5:00pm

Abstract

Motivated by neuroscience phenomena, the study of convex neural codes seeks to characterize how convex sets may intersect and overlap one another in Euclidean space. We will see how certain arrangements of convex sets, called sunflowers and flexible sunflowers, can help answer this question. In particular, we will describe a new Helly-type theorem that constrains these arrangements, and highlight several applications to the theory of convex neural codes. We will briefly contextualize these results by examining minors of codes, a framework that is somewhat analogous to minors of graphs.
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Princeton
Wed 30 Sep 2020, 3:00pm
Probability Seminar
https://ubc.zoom.us/s/67941158154?pwd=TDRjdm1ta2Fxbi9tVjJyaWdKb3A5QT09
Mixing time of the upper triangular matrix walk over Z/mZ
https://ubc.zoom.us/s/67941158154?pwd=TDRjdm1ta2Fxbi9tVjJyaWdKb3A5QT09
Wed 30 Sep 2020, 3:00pm-4:30pm

Abstract

We study a natural random walk over the upper triangular matrices, with entries in Z/mZ, generated by steps which add or subtract row i+1 to row i. We show that the mixing time of the lazy random walk is O((nm)^2) which is optimal up to constants. This generalizes a result of Peres and Sly and answers a question of Stong and of Arias-Castro, Diaconis and Stanley. This is joint work with Allan Sly.
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Adrianne Jenner
Universite de Montreal
Wed 14 Oct 2020, 1:45pm
Mathematical Biology Seminar
TBD
Improving oncolytic virotherapy using hybrid PDE/agent-based models and ODE systems
TBD
Wed 14 Oct 2020, 1:45pm-2:45pm

Abstract

Developing effective cancer treatment presents a unique challenge due to the overwhelming variability in tumour cell behaviour and spatial heterogeneity. Virotherapy is a type of cancer treatment that uses genetically engineered viruses to infect and lyse cancerous cells. When these viruses are administered with immune cells or immunostimulatory cytokines, an antitumour immune response is instigated. Developing a hybrid PDE/agent-based modelling for the treatment of glioblastoma (a type brain cancer), we predicted the variability in glioblastoma cells that hinders the efficacy of oncolytic virotherapy. We then show how this treatment could be improved for the majority of patients. Recently, gel-based mediums have been used to improve the efficacy of oncolytic virotherapy by providing a sustained therapeutic delivery of the vectors . Using a system of ODEs and a genetic algorithm, we show how this treatment could be further optimised by changing the gel-material to reduce the immune cell release rate. Overall, this talk aims to demonstrate complementing mathematical models and their applications in oncolytic virotherapy.
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UBC
Fri 16 Oct 2020, 3:00pm
Department Colloquium
Zoom
TBA
Zoom
Fri 16 Oct 2020, 3:00pm-4:00pm

Abstract

TBA
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Columbia
Tue 20 Oct 2020, 3:30pm
Diff. Geom, Math. Phys., PDE Seminar
Online
TBA
Online
Tue 20 Oct 2020, 3:30pm-4:30pm

Abstract


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Northwestern University
Fri 30 Oct 2020, 3:00pm SPECIAL
Department Colloquium
online -- TBA
Forecasting the 2020 U.S. elections: a compartmental modeling approach
online -- TBA
Fri 30 Oct 2020, 3:00pm-4:00pm

Abstract

Election dynamics are a rich complex system, and forecasting next month's U.S. elections is an exciting, high-stakes problem with many sources of subjectivity and uncertainty. In this talk, we take a dynamical-systems perspective on election forecasting, with the goal of helping to shed light on the forecast process and raise questions for future work. By adapting a well-studied model from epidemiology, we show how to combine a compartmental approach with polling data to produce forecasts of presidential, senatorial, and gubernatorial elections at the state level. Our results for the last 16 years of U.S. elections are largely in agreement with those of popular analysts, and we apply our model to forecast the upcoming U.S. elections on 3 November 2020. We also use our modeling framework to explore how different methods for handling polling data and accounting for uncertainty affect forecasts.

This is joint work with Samuel Chian, William He, Christopher Lee, Daniel Linder, Mason Porter, and Grzegorz Rempala.

Note for Attendees

 Rising Stars Colloquium
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Marius Lemm
EPFL
Tue 3 Nov 2020, 11:00am
Diff. Geom, Math. Phys., PDE Seminar
Zoom
TBA
Zoom
Tue 3 Nov 2020, 11:00am-12:00pm

Abstract

TBA
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ETH Zurich, will move to NYU
Fri 20 Nov 2020, 3:00pm
Department Colloquium
TBD
Faculty of Science Early Career Invited Lecture: TBD
TBD
Fri 20 Nov 2020, 3:00pm-3:50pm

Abstract


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UC Irvine
Thu 18 Mar 2021, 3:30pm SPECIAL
Diff. Geom, Math. Phys., PDE Seminar
TBA
TBA
TBA
Thu 18 Mar 2021, 3:30pm-4:30pm

Abstract

 
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UC Irvine
Fri 19 Mar 2021, 3:00pm
Department Colloquium
TBA
PIMS-UBC Rising Star Colloquium
TBA
Fri 19 Mar 2021, 3:00pm-4:00pm

Abstract

 
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Conor Mooney
Fri 19 Mar 2021, 3:00pm SPECIAL
Rising Star Colloquium
Fri 19 Mar 2021, 3:00pm-4:00pm

Details

 
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Ciprian Manolescu
Stanford University
Fri 26 Mar 2021, 3:00pm
Department Colloquium
ESB1012
PIMS-UBC Distinguished Colloquium
ESB1012
Fri 26 Mar 2021, 3:00pm-4:00pm

Abstract

 
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