Active filaments I: Curvature and torsion generation
Kaczmarski, B Moulton, D Kuhl, E Goriely, A Journal of the Mechanics and Physics of Solids volume 164 (10 May 2022)
Thu, 05 May 2022

16:00 - 17:00
L5

Gaussian distribution of squarefree and B-free numbers in short intervals

Alexander Mangerel
(Durham University)
Abstract
(Joint with O. Gorodetsky and B. Rodgers) It is a classical quest in analytic number theory to understand the fine-scale distribution of arithmetic sequences such as the primes. For a given length scale h, the number of elements of a "nice" sequence in a uniformly randomly selected interval $(x,x+h], 1 \leq x \leq X$, might be expected to follow the statistics of a normally distributed random variable (in suitable ranges of $1 \leq h \leq X$).  Following the work of Montgomery and Soundararajan, this is known to be true for the primes, but only if we assume several deep and long-standing conjectures among which the Riemann Hypothesis. In fact, previously such distributional results had not been proven for any (non-trivial) sequence of number-theoretic interest, unconditionally.

As a model for the primes, in this talk I will address such statistical questions for the sequence of squarefree numbers, i.e., numbers not divisible by the square of any prime, among other related ``sifted'' sequences called B-free numbers. I hope to further motivate and explain our main result that shows, unconditionally, that short interval counts of squarefree numbers do satisfy Gaussian statistics, answering several questions of R.R. Hall.

Droplets on lubricated surfaces: the slow dynamics of skirt formation
Dai, Z Vella, D Physical Review Fluids volume 7 (27 May 2022)
Constancy of the dimension in codimension one and locality of the unit normal on RCD(K,N) spaces
Bruè, E Pasqualetto, E Semola, D Annali della Scuola Normale Superiore di Pisa, Classe di Scienze
Tue, 17 May 2022

12:30 - 13:30
C5

Finite element methods for the Stokes–Onsager–Stefan–Maxwell equations of multicomponent flow

Francis Aznaran
(Mathematical Institute (University of Oxford))
Abstract

The Onsager framework for linear irreversible thermodynamics provides a thermodynamically consistent model of mass transport in a phase consisting of multiple species, via the Stefan–Maxwell equations, but a complete description of the overall transport problem necessitates also solving the momentum equations for the flow velocity of the medium. We derive a novel nonlinear variational formulation of this coupling, called the (Navier–)Stokes–Onsager–Stefan–Maxwell system, which governs molecular diffusion and convection within a non-ideal, single-phase fluid composed of multiple species, in the regime of low Reynolds number in the steady state. We propose an appropriate Picard linearisation posed in a novel Sobolev space relating to the diffusional driving forces, and prove convergence of a structure-preserving finite element discretisation. The broad applicability of our theory is illustrated with simulations of the centrifugal separation of noble gases and the microfluidic mixing of hydrocarbons.

A method for the inference of cytokine interaction networks
Coles, M Jansen, J Uhlig, H Aschenbrenner, D Gaffney, E PLoS Computational Biology volume 18 issue 6 (22 Jun 2022)
Convergence and Implicit Regularization Properties of Gradient Descent for Deep Residual Networks
Cont, R Rossier, A Xu, R (01 Jan 2022)
Conormal spaces and Whitney stratifications
Helmer, M Nanda, V Foundations of Computational Mathematics volume 23 1745-1780 (14 Jun 2022)
A note on the rational homological dimension of lattices in positive characteristic
Hughes, S Glasgow Mathematical Journal volume 65 issue 1 138-140 (10 Jun 2022)
Tue, 03 May 2022

12:00 - 13:00
L4

Burns holography

Atul Sharma
((Oxford University))
Abstract

Holography in asymptotically flat spaces is one of the most coveted goals of modern mathematical physics. In this talk, I will motivate a novel holographic description of self-dual SO(8) Yang-Mills + self-dual conformal gravity on a Euclidean signature, asymptotically flat background called Burns space. The holographic dual lives on a stack of D1-branes wrapping a CP^1 cycle in the twistor space of R^4 and is given by a gauged beta-gamma system with SO(8) flavor and a pair of defects at the north and south poles. It provides the first example of a stringy realization of (asymptotically) flat holography and is a Euclidean signature variant of celestial holography. This is based on ongoing work with Kevin Costello and Natalie Paquette.

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