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Abstract not available

• Speaker: Elyes Boughattas (University of Rennes 1)
• Tuesday 18 November 2025, 14:30-15:30
• Venue: MR13.
• Series: Number Theory Seminar; organiser: Bence Hevesi.

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Abstract not available

• Speaker: Gyujin Oh (Columbia University)
• Tuesday 04 November 2025, 14:30-15:30
• Venue: MR13.
• Series: Number Theory Seminar; organiser: Bence Hevesi.

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Abstract not available

• Speaker: Katerina Santicola (University of Bath)
• Tuesday 21 October 2025, 14:30-15:30
• Venue: MR13.
• Series: Number Theory Seminar; organiser: Bence Hevesi.

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I will introduce higher Hida theory for Hilbert modular forms. This is a theory of higher coherent cohomological ordinary p-adic modular forms, which can be thought of as p-adically interpolating non holomorphic Hilbert modular forms. Then I will explain a Jacquet-Langlands type correspondence with certain quaternionic modular forms, which is explained by the existence of “exotic Hecke correspondences” which exist modulo powers of p. This is joint work with Vincent Pilloni.

• Speaker: George Boxer (Imperial College London)
• Tuesday 14 October 2025, 14:30-15:30
• Venue: MR13.
• Series: Number Theory Seminar; organiser: Bence Hevesi.

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Abstract not available

• Speaker: Dr. Ian Mcgough, Babraham Institute
• Friday 31 October 2025, 13:00-14:00
• Venue: Biffen Theater- Please subscribe to mailing list for link.
• Series: Developmental Biology Seminar Series; organiser: lb935.

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Abstract not available

• Speaker: Isabel Rendell (LSGNT)
• Tuesday 02 December 2025, 14:30-15:30
• Venue: MR13.
• Series: Number Theory Seminar; organiser: Dmitri Whitmore.

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Abstract not available

• Speaker: Zachary Feng (University of Oxford)
• Tuesday 25 November 2025, 14:30-15:30
• Venue: MR13.
• Series: Number Theory Seminar; organiser: Dmitri Whitmore.

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Abstract not available

• Speaker: Xiangqian Yang (Peking University)
• Tuesday 28 October 2025, 14:30-15:30
• Venue: MR13.
• Series: Number Theory Seminar; organiser: Dmitri Whitmore.

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Abstract not available

• Speaker: Andrea Dotto (King's College London)
• Tuesday 11 November 2025, 14:30-15:30
• Venue: MR13.
• Series: Number Theory Seminar; organiser: Dmitri Whitmore.

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Abstract not available

• Speaker: Vicki Metzis, Imperial College London
• Friday 28 November 2025, 13:00-14:00
• Venue: Biffen Theater- Please subscribe to mailing list for link.
• Series: Developmental Biology Seminar Series; organiser: John Russell.

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Abstract not available

• Speaker: Claire Senner, Loke Centre for Trophoblast Research
• Friday 14 November 2025, 13:00-14:00
• Venue: Biffen Theater- Please subscribe to mailing list for link.
• Series: Developmental Biology Seminar Series; organiser: Theresa Gross-Thebing.

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TBC

• Speaker: David Abrahams, DAMTP, University of Cambridge
• Friday 05 December 2025, 16:00-17:00
• Venue: MR2.
• Series: Fluid Mechanics (DAMTP); organiser: Duncan Hewitt.

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TBC

• Speaker: Quentin Kriaa, DAMTP, University of Cambridge
• Friday 07 November 2025, 16:00-17:00
• Venue: MR2.
• Series: Fluid Mechanics (DAMTP); organiser: Duncan Hewitt.

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Over the time-scales of seconds to years that are associated with processes such as seismic wave propagation, tidal deformation, and rotational variations, the Earth’s crust, mantle and inner core are viscoelastic solids, while the outer core and oceans are compressible fluids whose viscosity’s are sufficiently low as to be commonly neglected. Were it not for the presence of the fluid regions, an essentially complete mathematical description of the dynamics could be developed, and the numerical solution of the resulting equations would present no essential difficulties. In this talk I will discuss some of the remaining challenges, both theoretical and computational, that arise within these applications due to the presence of fluid regions and point to some possible methods for their resolution.

• Speaker: David Al-Attar, DES, University of Cambridge
• Friday 17 October 2025, 16:00-17:00
• Venue: MR2.
• Series: Fluid Mechanics (DAMTP); organiser: Duncan Hewitt.

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The response of the polymeric stress in the Oldroyd-B model to various planar flow kinematics is probed. By focusing on the two invariants of the conformation tensor©, namely the trace (tr) and determinant (det), (or, equivalently, the sum and the product of the two eigenvalues) the domain of realisable stress states are mapped. Previous theoretical bounds have been (re)proposed for 2D flows, viz det C 1 and therefore tr C 2 (det C)1/2 ((Hulsen (1988), Hu & Lelièvre (2007), Yerasi et al (2024)).

For all steady homogeneous 2D flows, including flows tending to solid body rotation, steady shearing, planar extension (and all flows in between these bounds), plus fully developed channel flow (i.e. inhomogeneous shearing) and flows next to all continuous walls without sharp corners, we show that tr C = 2 det C. Start-up shearing and planar extension are seen to approach the steady flow relationship in a differing manner, whilst large amplitude oscillatory shearing (LAOS) and extension (LAOE) exhibit rich kinematics. We find the lower theoretical bound (tr C 2 (det C)1/2) is only approached for strongly time varying extensional kinematics (LAOE with De~O(0.1)) and many other flows appear bound by tr C = 1 + det C (start up extension, LAOS ).

Limited results from more complex benchmark flows involving mixed shear and extension (steady in a Eulerian sense), including flow past a confined cylinder in a channel, the cross slot and flow in a 4:1 contraction fall within the bounds of those “simpler” kinematics. Extensions of the approach to more complicated models, such as the simplified Phan-Thien and Tanner and the FENE -P models, will also briefly be discussed. The results here may be useful in determining bounds for numerical computations or providing information regarding what rheological tests produce similar stress state responses to more complex flows.

• Speaker: Robert Poole, University of Liverpool
• Friday 28 November 2025, 16:00-17:00
• Venue: MR2.
• Series: Fluid Mechanics (DAMTP); organiser: Duncan Hewitt.

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The currently ongoing climate change and the debate about possible measures to be taken to limit the consequences of climate change, requires to know and understand the future response of the climate system to greenhouse gas emissions. Classical measures of climate change such as the Equilibrium Climate Sensitivity are inherently linear and unable to account for abrupt transitions due to (interacting) tipping elements.

In this presentation I will discuss more general notions of climate sensitivity defined on a climate attractor that can be useful in understanding the response of a climate state to changes in radiative forcing. For example, a climate state close to a tipping point will have a degenerate linear response to perturbations, which can be associated with extreme values of the climate sensitivity. While many identified tipping elements in the climate system are regional and may have no direct impact on the global mean temperature, cascades of tipping elements can potentially have an impact, initiated by the threshold of the leading tipping element in a cascade.

I will also showcase a few examples of large scale climate tipping elements and their interactions, in particular related to the Atlantic Meridional Overturning Circulation and polar ice sheets.

• Speaker: Anna von der Heydt, Utrecht University
• Friday 14 November 2025, 16:00-17:00
• Venue: MR2.
• Series: Fluid Mechanics (DAMTP); organiser: Duncan Hewitt.

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TBC

• Speaker: Matilda Backholm, Aalto University
• Friday 31 October 2025, 16:00-17:00
• Venue: MR2.
• Series: Fluid Mechanics (DAMTP); organiser: Duncan Hewitt.

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Abstract:

In the field of engineered systems, the integration of machine learning has enabled the development of advanced predictive models that ensure the reliable operation of complex assets. However, challenges such as sparse, noisy, and incomplete data necessitate the integration of prior knowledge and inductive bias to improve generalization, interpretability, and robustness.

Inductive bias, the set of assumptions embedded in machine learning models, plays a crucial role in guiding these models to generalize effectively from limited training data to real-world scenarios. In engineered systems, where physical laws and domain-specific knowledge are fundamental, the use of inductive bias can significantly enhance a model’s ability to predict system behavior under diverse operating conditions. By embedding physical principles into learning algorithms, inductive bias reduces the reliance on large datasets, ensures that model predictions are physically consistent, and enhances both the generalizability and interpretability of the models.

This talk will explore various forms of inductive bias applied in engineered systems, with a particular focus on heterogenous spatio-temporal, and physics-informed graph neural networks, as well as symbolic regression with applications in virtual sensing, modelling multi-body dynamical systems and anomaly detection.

Olga Fink

Assistant Professor of Intelligent Maintenance and Operations Systems, EPFL , Lausanne

Short Bio:

Olga Fink has been assistant professor at EPFL since March 2022, heading the Intelligent Maintenance and Operations Systems (IMOS) laboratory. Olga’s research focuses on Physics-Informed Machine Learning, Multi-Modal Learning, Domain Adaptation and Generalization, and Reinforcement Learning for Intelligent Maintenance and Operations of Infrastructure and Complex Assets.

Before joining EPFL faculty, Olga was assistant professor of intelligent maintenance systems at ETH Zurich from 2018 to 2022, being awarded the prestigious professorship grant of the Swiss National Science Foundation (SNSF). Between 2014 and 2018 she was heading the research group “Smart Maintenance” at the Zurich University of Applied Sciences (ZHAW).

Olga received her Ph.D. degree from ETH Zurich, and Diploma degree from Hamburg University of Technology. She has gained valuable industrial experience as reliability engineer with Stadler Bussnang AG and as reliability and maintenance expert with Pöyry Switzerland Ltd.

Olga is serving as an editorial board member of several prestigious journals, including Mechanical Systems and Signal Processing, Engineering Applications of Artificial Intelligence and Reliability Engineering and System Safety.

In 2019, Olga earned the distinction of being recognized as a young scientist of the World Economic Forum. In 2020, 2021, and 2024 she was honored as a young scientist of the World Laureate Forum. In 2023, she was distinguished as a fellow by the Prognostics and Health Management Society

• Speaker: Dr Olga Fink, EPFL, Switzerland
• Friday 07 November 2025, 16:00-17:00
• Venue: JDB Seminar Room, CUED.
• Series: Engineering - Dynamics and Vibration Tea Time Talks; organiser: div-c.

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Turbulent convection processes are ubiquitous in nature and technology. We study the structure of thermal and viscous boundary layers in three-dimensional Rayleigh-Bénard convection, a paradigm of these natural flows, for a range of Rayleigh numbers that spans 6 orders of magnitude by means of direct numerical simulations. The configuration is a plane layer of aspect ratio 4 with periodic boundary conditions at the sides – the configuration that comes close to the original configuration studied by Lord Rayleigh and others. Velocity fluctuations dominate the near-wall regions at all Rayleigh numbers. A global mean flow, which is a prerequisite for several theoretical models of turbulent heat transfer, is practically absent. Rather, the velocity field close to the wall can be decomposed into regions that are dominated by local, differently oriented and transient shear motion with shear-free regions in between. Thermal plumes are found to be organized in a self-similar hierarchical network, which gets coarser with increasing distance from the wall. The thermal boundary layers are marginally stable; the critical wavelength bounds the mean thermal plume spacing in the hierarchical network for all Rayleigh numbers from below. Our studies thus underline that the character of the near-wall layers in plane-layer Rayleigh-Bénard convection differs from those of canonical wall-bounded shear flows.

• Speaker: Jörg Schumacher, Technische Universität Ilmenau
• Friday 24 October 2025, 16:00-17:00
• Venue: MR2.
• Series: Fluid Mechanics (DAMTP); organiser: Duncan Hewitt.

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We assess a prognostic formulation of triple coherence relating to energy exchange between mesoscale eddies and the internal wavefield and compare with observations from the Sargasso Sea.

We break new ground in the following ways: (1) We utilize concepts from Open Quantum Systems to arrive at the essential results presented in Muller 1976, JFM , where eddy induced internal wave-stress perturbations are damped using a nonlinear relaxation time scale approximation. The broad brush take on Open Quantum Systems is that there is a system (ray tracing), a bath (the background internal wavefield) and a system bath interaction (nonlinear relaxation). We avoid the asymptotic expansion involving small perturbations to wave phase speed that is the basis of Muller.

(2) We define the background internal wave spectrum based upon a regional characterization of the wavefield in the Sargasso Sea. This differs from the canonical description referred to as GM76 in crucial respects.

(3) We use recent theoretical work on both extreme scale separated interactions and the internal wave kinetic equation to properly define nonlinear relaxation time scales.

Agreement of the prognostic formulation with data is remarkable and is consistent with eddy-wave coupling dominating the regional internal wave energy budget, as in the diagnostic study of Polzin 2010, JPO , using data from the Local Dynamics Experiment of PolyMode III , circa 1978-1979. Extraction of eddy energy happens at the horizontal and vertical scales that characterize baroclinic instability and potential vorticity fluxes. The goodness of this effort reinforces a prior hypothesis (Polzin and Lvov 2011, RoG) that the character of the internal wavefield in the Sargasso Sea is set by this interaction, which, in turn, serves as an amplifier of tertiary energy inputs from larger vertical scales that characterize internal swell. With this knowledge and confidence, we then speculate on the role that this coupling plays in mesoscale eddy dynamics in the Southern Recirculation Gyre of the Gulf Stream. In this instance our interest is the potential enstrophy budget, in which enstrophy is the square of the perturbation potential vorticity and, as is energy, an inviscid invariant.

We argue that this nonlinear relaxation effectively provides a local eddy enstrophy damping consistent with potential vorticity flux observations from the Local Dynamics Experiment. This happens at spatial scales somewhat smaller than the energy extraction scale and locates the end of the potential enstrophy cascade in the spectral domain as the energy containing scale of the internal wavefield. We offer insight into how such speculation might acquire firmer ground by ​ describing how to incorporate modulations of the lower bound of internal wave frequency by potential vorticity perturbations into the existing formulation. In the context of a formal WKB approximation, the current formulation stands as a ‘geometric optics’ approximation controlling system behavior whereas modulations of the waveguide are a ‘physical optics’ correction.

Regardless, the dynamical consequence is that wave-eddy coupling is responsible for the maintenance of gyre scale potential vorticity gradients that are crucial to Rossby wave propagation and Earth system behavior.

• Speaker: Kurt Polzin, Woods Hole Oceanographic Institution
• Friday 10 October 2025, 16:00-17:00
• Venue: MR2.
• Series: Fluid Mechanics (DAMTP); organiser: Duncan Hewitt.

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