Mon, 28 Feb 2022

16:00 - 17:00
C4

Joint moments of characteristic polynomials of random unitary matrices

Arun Soor
Abstract

The moments of Hardy’s function have been of interest to number theorists since the early 20th century, and to random matrix theorists especially since the seminal work of Keating and Snaith, who were able to conjecture the leading order behaviour of all moments. Studying joint moments offers a unified approach to both moments and derivative moments. In his 2006 thesis, Hughes made a version of the Keating-Snaith conjecture for joint moments of Hardy’s function. Since then, people have been calculating the joint moments on the random matrix side. I will outline some recent progress in these calculations. This is joint work with Theo Assiotis, Benjamin Bedert, and Mustafa Alper Gunes.

Mon, 21 Feb 2022

16:00 - 17:00
C2

TBA

Julia Stadlmann
Mon, 14 Feb 2022

16:00 - 17:00
C4

TBA

Mon, 07 Feb 2022

16:00 - 17:00
C2

TBA

Mon, 31 Jan 2022

16:00 - 17:00
L5

The Probabilistic Zeta Function of a Finite Lattice

Besfort Shala
Abstract

In this talk, we present our study of Brown’s definition of the probabilistic zeta function of a finite lattice, and propose a natural alternative that may be better-suited for non-atomistic lattices. The probabilistic zeta function admits a general Dirichlet series expression, which need not be ordinary. We investigate properties of the function and compute it on several examples of finite lattices, establishing connections with well-known identities. Furthermore, we investigate when the series is an ordinary Dirichlet series. Since this is the case for coset lattices, we call such lattices coset-like. In this regard, we focus on partition lattices and d-divisible partition lattices and show that they typically fail to be coset-like. We do this by using the prime number theorem, establishing a connection with number theory.

Mon, 24 Jan 2022

16:00 - 17:00
C2

TBA

Yifan Jing
Mon, 17 Jan 2022

16:00 - 17:00
C4

Classical Mechanics and Diophantine Equations

Jay Swar
Abstract

We'll sketch how the $K$-rational solutions of a system $X$ of multivariate polynomials can be viewed as the solutions of a "classical mechanics" problem on an associated affine space.

When $X$ has a suitable topology, e.g. if its $\mathbb{C}$-solutions form a Riemann surface of genus $>1$, we'll observe some of the advantages of this new point of view such as a relatively computable algorithm for effective finiteness (with some stipulations). This is joint work with Minhyong Kim.
 

Tue, 01 Feb 2022
14:00
L5

Numerical quadrature for singular integrals on fractals

Dave Hewett
(University College London)
Abstract

How can one integrate singular functions over fractals? And why would one want to do this? In this talk I will present a general approach to numerical quadrature on the compact attractor of an iterated function system of contracting similarities, where integration is with respect to the relevant Hausdorff measure. For certain singular integrands of logarithmic or algebraic type the self-similarity of the integration domain can be exploited to express the singular integral exactly in terms of regular integrals that can be approximated using standard techniques. As an application we show how this approach, combined with a singularity-subtraction technique, can be used to accurately evaluate the singular double integrals that arise in Hausdorff-measure Galerkin boundary element methods for acoustic wave scattering by fractal screens. This is joint work with Andrew Gibbs (UCL) and Andrea Moiola (Pavia).

Tue, 15 Feb 2022
14:00
L5

Extracting Autism's Biomarkers in Placenta Using Multiscale Methods

Karamatou Yacoubou Djima
(Amherst College)
Abstract

The placenta is the essential organ of maternal-fetal interactions, where nutrient, oxygen, and waste exchange occur. In recent studies, differences in the morphology of the placental chorionic surface vascular network (PCSVN) have been associated with developmental disorders such as autism. This suggests that the PCSVN could potentially serve as a biomarker for the early diagnosis and treatment of autism. Studying PCSVN features in large cohorts requires a reliable and automated mechanism to extract the vascular networks. In this talk, we present a method for PCSVN extraction. Our algorithm builds upon a directional multiscale mathematical framework based on a combination of shearlets and Laplacian eigenmaps and can isolate vessels with high success in high-contrast images such as those produced in CT scans. 

 
Evaluating strategies for spatial allocation of vaccines based on risk and centrality
Singer, B Thompson, R Bonsall, M Journal of the Royal Society Interface volume 19 issue 187 (16 Feb 2022)
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