Tuesday 5 December 2023, 13:00-14:00
Lecture room A, Watson building
A rotating stratified fluid such as the atmosphere or ocean is characterised by the coexistence of inertia-gravity waves and turbulent vortical flow. The two interact leading to a redistribution of wave energy in what is approximately a diffusion process in wavevector space. The corresponding diffusivity is derived using matched asymptotics under the assumption that the background flow is time independent. The solution to this diffusion equation is localised to the constant-frequency surface, a cone in wavevector space. Relaxing the assumption of flow time independence causes weak diffusion across the cone. We examine how this weak diffusion affects the wave energy distribution by solving the steady-state, forced system. We find the resultant energy spectrum decays rapidly within a boundary layer about the cone, showing good agreement with a 3D Boussinesq simulation.
Tuesday 16 January 2024, 13:00-14:00
Venue to be confirmed
Abstract not available
Tuesday 30 January 2024, 13:00-14:00
Venue to be confirmed
Abstract not available
Tuesday 6 February 2024, 13:00-14:00
Venue to be confirmed
Abstract not available
Tuesday 13 February 2024, 13:00-14:00
Venue to be confirmed
Abstract not available
Tuesday 27 February 2024, 13:00-14:00
Venue to be confirmed
Abstract not available
Tuesday 5 March 2024, 13:00-14:00
Venue to be confirmed
Abstract not available
Tuesday 12 March 2024, 13:00-14:00
Venue to be confirmed
Abstract not available
Tuesday 12 March 2024, 13:00-14:00
Venue to be confirmed
Abstract not available
Tuesday 12 March 2024, 13:00-14:00
Venue to be confirmed
Abstract not available
Tuesday 28 November 2023, 13:00-14:00
Lecture room A, Watson building
Atherosclerotic plaques form in the linings of large arteries where the blood flow is disrupted. These plaques are implicated in various types of vascular disease, including, most importantly, heart attack and stroke. These adverse events occur when a plaque ruptures, and spills its contents into the bloodstream leading to the formation of blood clots that may block coronary or cerebral arteries. Plaque formation leads to various mechanically important outcomes, including distention of the artery wall, plaque rupture and the thinning of the cap that covers the plaque. These mechanical outcomes are driven by the underlying behaviour of cells, principally macrophages, within the plaque to produce plaque expansion and cap formation. In this talk I will survey models for cellular events and behaviour that have been produced by our group, focusing particularly on mid-stage plaque and show how these events link to plaque structure and composition.
Friday 17 November 2023, 13:00-14:00
Arts LR1
Mathematical and computational techniques can improve our understanding of diseases. In this talk, I’ll present ways in which data from cancer patients can be combined with mathematical modelling and used to improve cancer treatments. Given the variability in individual responses to cancer treatments, agent-based modelling has been a useful technique for accurately capturing cellular behaviours that may lead to stochasticity in patient outcomes. Using a hybrid agent-based model and partial differential equation system, we developed a model for brain cancer (glioblastoma) growth informed by ex-vivo patient samples. Extending the model to capture patient treatment with an oncolytic virus rQNestin, we used our model to propose reasons for treatment failure, which was later confirmed with further patient samples. More recently, we extended this model to investigate the effectiveness of combination treatments (chemotherapy, virotherapy and immunotherapy) informed by individual patient imaging mass cytometry. This talk hopes to provide examples of ways mathematical and computational modelling can be used to run “virtual” clinical trials with the goal of obtaining more effective treatments for diseases.
Tuesday 14 November 2023, 13:00-14:00
Lecture room A, Watson building
Understanding the flow of droplets that are suspended/immersed in other fluids is crucial in a variety of applications, including drug delivery, pharmaceutical manufacturing, and respiratory infection. Such flows are typically three-dimensional, often held in opaque settings or include opaque fluids, and involve mass transfer between the droplets and the surrounding fluid. These traits combined make it extremely challenging to simultaneously keep track of the time-dependent position, size, and shape of droplets using standard experimental methods. Positron imaging, i.e., the use of radioactive tracer to label materials and visualise them by recording their radioactive decay, is a widely used method in diagnosing cancer and other diseases, which we employ to study the motion and dynamics of droplets. In this talk, I will give a short overview of the positron imaging techniques we use to study the flow of droplets, in collaboration with the Positron Imaging Centre at the University of Birmingham. I will elaborate on the key role of modelling in quantifying the uncertainty in these measurements and in allowing for fast, real-time imaging of droplet flows.
Tuesday 31 October 2023, 13:00-14:00
Lecture room A, Watson building
Social network data can give us a powerful view of our health inequalities but obtaining and sharing it can be very challenging. We have been developing an alternative view in which small amounts of network data can be used to constrain a family of network models allowing network-based social reasoning with incomplete information. I’ll cover how we can find dense regions in networks from time-series data, how we can infer network structure from static voting behaviour or coarsened graphs and how to combine social survey data with census microdata to obtain a principled generalization of the Gini index. On the way I’ll comment on evidence that lots of social behaviour can be understood as a strong-field setting of spin-systems. In conventional network science one computes statistics like the betweenness-centrality of nodes, given a fully observed network; we provide extensive analytic results that allow us to efficiently compute these (geodesic) statistics when the network is only partially observed. This allows us to link health outcomes for individuals with their position in partially observed social networks. Depending on time I will also cover some recent work on an alternative evolutionary mechanism to replicative advantage that allows mutations to spread through populations while having a replicative disadvantage. The effect is intrinsically stochastic and has links to the spread of altruistic traits. The mechanism we describe offers a solution to a decades old problem in mitochondrial genetics, in a manner consonant with data, and which indicates new routes to combat muscle ageing.
Tuesday 24 October 2023, 13:00-14:00
Lecture room A, Watson building
“In that Empire, the Art of Cartography attained such Perfection that the map of a single Province occupied the entirety of a City, and the map of the Empire, the entirety of a Province. In time, those Unconscionable Maps no longer satisfied, and the Cartographers Guilds struck a Map of the Empire whose size was that of the Empire, and which coincided point for point with it. The following Generations, who were not so fond of the Study of Cartography as their Forebears had been, saw that that vast map was Useless, and not without some Pitilessness was it, that they delivered it up to the inclemencies of Sun and Winters. In the Deserts of the West, still today, there are Tattered Ruins of that Map, inhabited by Animals and Beggars; in all the Land there is no other Relic of the Disciplines of Geography.” Del rigor en la ciencia, Jorge Luis Borges
Tuesday 17 October 2023, 13:00-14:00
Lecture room A, Watson building
BHV space is a well-studied moduli space of phylogenetic trees that appears in many scientific disciplines, including computational biology, computer vision, combinatorics, and category theory. Speyer and Sturmfels identify a homeomorphism between BHV space and a version of the Grassmannian using tropical geometry, endowing the space of phylogenetic trees with a tropical structure, which turns out to be advantageous for computational studies. In this talk, I will present the coincidence between BHV space and the tropical Grassmannian. I will then give an overview of some recent work I have done that studies the tropical Grassmannian as a metric space and the practical implications of these results on probabilistic and statistical studies on sets of phylogenetic trees.
Tuesday 10 October 2023, 13:00-14:00
ARTS Lecture Room 5 (219)
Active drops are synthetic, micron-sized “swimmers” that convert chemical energy into mechanical motion. These drops are physico-chemically isotropic and emit/absorb chemical solutes, whose concentration gradients cause interfacial flows which drive the solute’s own transport via advection. This nonlinear coupling between the fluid flow and solute transport around the drop can cause a spontaneous symmetry-breaking, leading to sustained interfacial flows and self-propulsion of the drop, provided the ratio of convective-to-diffusive solute transport, or Peclet number, is large enough. As a result of their net buoyancy, active drops typically evolve at small finite distances from rigid boundaries. Yet, existing theoretical models on drop propulsion systematically focus on unbounded flows, due to their geometrical simplicity. Using numerical simulations, we address this gap in understanding and provide physical insights on the spontaneous emergence and nonlinear saturation of the propulsion of active drops along a rigid wall. Specifically, we show that, and explain why, a reduction in the drop-to-wall separation actually promotes the drop’s self-propulsion.