Fri, 17 May 2024

14:00 - 15:00
L3

Some consequences of phenotypic heterogeneity in living active matter

Dr Philip Pearce
(Dept of Mathematics UCL)
Abstract

In this talk I will discuss how phenotypic heterogeneity affects emergent pattern formation in living active matter with chemical communication between cells. In doing so, I will explore how the emergent dynamics of multicellular communities are qualitatively different in comparison to the dynamics of isolated or non-interacting cells. I will focus on two specific projects. First, I will show how genetic regulation of chemical communication affects motility-induced phase separation in cell populations. Second, I will demonstrate how chemotaxis along self-generated signal gradients affects cell populations undergoing 3D morphogenesis.

Fri, 10 May 2024

14:00 - 15:00
L3

The determining role of cell adhesions for force transmission, mechanical activity and stiffness sensing in cells and tissues

Dr Carina Dunlop
(Dept of Mathematics University of Surrey)
Abstract

The role of tissue stiffness in controlling cell behaviours ranging from proliferation to signalling and activation is by now well accepted. A key focus of experimental studies into mechanotransduction are focal adhesions, localised patches of strong adhesion, where cell signalling has been established to occur. However, these adhesion sites themselves alter the mechanical equilibrium of the system determining the force balance and work done. To explore this I have developed an active matter continuum description of cellular contractility and will discuss recent results on the specific role of spatial positioning of adhesions in mechanotransduction. I show using energy arguments why the experimentally observed arrangements of focal adhesions develop and the implications this has for stiffness sensing and cellular contractility control. I will also show how adhesions play distinct roles in single cells and tissue layers respectively drawing on recent experimental work with Dr JR Davis (Manchester University) and Dr Nic Tapon (Crick Institute) with applications to epithelial layers and organoids.

Fri, 03 May 2024

14:00 - 15:00
L3

Epidemiological modelling with behavioural considerations and to inform policy making

Dr Edward Hill
(Dept of Mathematics University of Warwick)
Abstract
Many problems in epidemiology are impacted by behavioural dynamics, whilst in response to health emergencies prompt analysis and communication of findings is required to be of use to decision makers. Both instances are likely to benefit from interdisciplinary approaches. This talk will feature two examples, one with a public health focus and one with a veterinary health focus.
 
In the first part, I will summarise work originally conducted in late 2020 that was contributed to Scientific Pandemic Influenza Group on Modelling, Operational sub-group (SPI-M-O) of SAGE (Scientific Advisory Group for Emergencies) on Christmas household bubbles in England. This was carried out in response to a policy involving a planned easing of restrictions in England between 23–27 December 2020, with Christmas bubbles allowing people from up to three households to meet throughout the holiday period. Using a household model and computational simulation, we estimated the epidemiological impact of both this and alternative bubble strategies that allowed extending contacts beyond the immediate household.

(Associated paper: Modelling the epidemiological implications for SARS-CoV-2 of Christmas household bubbles in England in December 2020. https://doi.org/10.1016/j.jtbi.2022.111331)

In the second part, I will present a methodological pipeline developed to generate novel quantitative data on farmer beliefs with respect to disease management, process the data into a form amenable for use in mathematical models of livestock disease transmission and then refine said mathematical models according to the findings of the data. Such an approach is motivated by livestock disease models traditionally omitting variation in farmer disease management behaviours. I will discuss our application of this methodology for a fast, spatially spreading disease outbreak scenario amongst cattle herds in Great Britain, for which we elicited when farmers would use an available vaccine and then used the attained behavioural groups within a livestock disease model to make epidemiological and health economic assessments. 

(Associated paper: Incorporating heterogeneity in farmer disease control behaviour into a livestock disease transmission model. https://doi.org/10.1016/j.prevetmed.2023.106019)
Fri, 26 Apr 2024

14:00 - 15:00
L3

Polynomial dynamical systems and reaction networks: persistence and global attractors

Professor Gheorghe Craciun
(Department of Mathematics and Department of Biomolecular Chemistry, University of Wisconsin-Madison)
Abstract
The mathematical analysis of global properties of polynomial dynamical systems can be very challenging (for example: the second part of Hilbert’s 16th problem about polynomial dynamical systems in 2D, or the analysis of chaotic dynamics in the Lorenz system).
On the other hand, any dynamical system with polynomial right-hand side can essentially be regarded as a model of a reaction network. Key properties of reaction systems are closely related to fundamental results about global stability in classical thermodynamics. For example, the Global Attractor Conjecture can be regarded as a finite dimensional version of Boltzmann’s H-theorem. We will discuss some of these connections, as well as the introduction of toric differential inclusions as a tool for proving the Global Attractor Conjecture.
We will also discuss some implications for the more general Persistence Conjecture (which says that solutions of weakly reversible systems cannot "go extinct"), as well as some applications to biochemical mechanisms that implement cellular homeostasis. 
 


 

Thu, 29 Feb 2024

11:00 - 12:00
C3

Coherent group actions

Martin Bays
(University of Oxford)
Abstract

I will discuss aspects of some work in progress with Tingxiang Zou, in which we continue the investigation of pseudofinite sets coarsely respecting structures of algebraic geometry, focusing on algebraic group actions. Using a version of Balog-Szemerédi-Gowers-Tao for group actions, we find quite weak hypotheses which rule out non-abelian group actions, and we are applying this to obtain new Elekes-Szabó results in which the general position hypothesis is fully weakened in one co-ordinate.

The wheel classes in the locally finite homology of
$\mathrm{GL}_n(\mathbb{Z})$, canonical integrals and zeta values
 Brown, F Schnetz, O (09 Feb 2024) http://arxiv.org/abs/2402.06757v3
Structural identifiability analysis of linear reaction–advection–diffusion processes in mathematical biology
 Browning, A Tasca, M Falco, C Baker, R Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences volume 480 issue 2286 (27 Mar 2024)
Twistor Theory: Some Applications
 Mason, L Encyclopedia of Mathematical Physics: Five-Volume Set V5-303-V5-311 (01 Jan 2006)
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