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Microstructural Kinetics Group

Department of Materials Science & Metallurgy
 

Mon 01 Dec 13:00: Lunch at Churchill College OOEW10 - Scoping meeting: Computation, modelling, and statistical analysis of physiological and clinical brain signals for real-time classification and prediction

School of Physical Sciences - 1 hour 25 min ago
Lunch at Churchill College

OOEW10 - Scoping meeting: Computation, modelling, and statistical analysis of physiological and clinical brain signals for real-time classification and prediction

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Mon 01 Dec 12:05: Cot to Code and Back Again OOEW10 - Scoping meeting: Computation, modelling, and statistical analysis of physiological and clinical brain signals for real-time classification and prediction

School of Physical Sciences - 1 hour 25 min ago
Cot to Code and Back Again

OOEW10 - Scoping meeting: Computation, modelling, and statistical analysis of physiological and clinical brain signals for real-time classification and prediction

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Mon 01 Dec 11:00: Morning Break OOEW10 - Scoping meeting: Computation, modelling, and statistical analysis of physiological and clinical brain signals for real-time classification and prediction

School of Physical Sciences - 1 hour 25 min ago
Morning Break

OOEW10 - Scoping meeting: Computation, modelling, and statistical analysis of physiological and clinical brain signals for real-time classification and prediction

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Mon 01 Dec 10:05: Organiser's Welcome OOEW10 - Scoping meeting: Computation, modelling, and statistical analysis of physiological and clinical brain signals for real-time classification and prediction

School of Physical Sciences - 1 hour 25 min ago
Organiser's Welcome

OOEW10 - Scoping meeting: Computation, modelling, and statistical analysis of physiological and clinical brain signals for real-time classification and prediction

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Mon 01 Dec 10:00: Director's Briefing OOEW10 - Scoping meeting: Computation, modelling, and statistical analysis of physiological and clinical brain signals for real-time classification and prediction

School of Physical Sciences - 1 hour 25 min ago
Director's Briefing

OOEW10 - Scoping meeting: Computation, modelling, and statistical analysis of physiological and clinical brain signals for real-time classification and prediction

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Mon 01 Dec 09:30: Registration OOEW10 - Scoping meeting: Computation, modelling, and statistical analysis of physiological and clinical brain signals for real-time classification and prediction

School of Physical Sciences - 1 hour 25 min ago
Registration

OOEW10 - Scoping meeting: Computation, modelling, and statistical analysis of physiological and clinical brain signals for real-time classification and prediction

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Tue 09 Dec 10:00: Morning Break / Group Photo BIDW03 - The Many Faces of Boundaries, Impurities, and Defects

School of Physical Sciences - 2 hours 25 min ago
Morning Break / Group Photo

BIDW03 - The Many Faces of Boundaries, Impurities, and Defects

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Wed 26 Nov 10:15: Cohomological methods in stability OGGW04 - Stability and probabilistic methods

School of Physical Sciences - 2 hours 25 min ago
Cohomological methods in stability

For d≥4 and p a sufficiently large prime, we construct a lattice Γ≤PSp2d(ℚp), such that its universal central extension cannot be sofic if Γ satisfies some weak form of stability in permutations. In the proof, we make use of high-dimensional expansion phenomena. A key ingredient are new cohomological obstructions to weak containment of actions.

OGGW04 - Stability and probabilistic methods

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Tue 18 Nov 11:00: LiquidO opaque scintillator detectors and the physics opportunities

School of Physical Sciences - 2 hours 26 min ago
LiquidO opaque scintillator detectors and the physics opportunities

Radiation detectors enable many aspects of our modern lives, from the light sensors in our smartphone cameras to PET scanners that inform treatment of cancer. Particle physicists have often led the development and exploitation of cutting edge radiation detectors to identify particles while measuring their energies, positions and directions.

Many radiation detectors use scintillators, which traditionally have nearly always been transparent to allow detection of the light. Our new counter-intuitive approach called “LiquidO” is to use highly scattering opaque scintillator. The opacity causes the light to bounce around close to where it is produced and then optical fibres extract the light. By looking at which fibres are hit and how much light each one sees, precise particle position and directional information can be obtained. We’ve demonstrated that our approach outperforms existing scintillator technology by a factor of two. With further R&D the resolution is expected to improve by 5-10x, for a similar cost to existing technology. Or, importantly for some applications, reduce the detector cost by 5-10x while maintaining the resolution.

There are multiple applications for high-resolution and cost-effective radiation imaging, from Compton cameras for gamma ray imaging to precision muon tomography. In particle physics, the CLOUD neutrino experiment will pioneer new physics measurements using the novel LiquidO opaque scintillator technology.

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Wed 26 Nov 10:15: An introduction to primary cohomological obstructions to group stability OGGW04 - Stability and probabilistic methods

School of Physical Sciences - 3 hours 25 min ago
An introduction to primary cohomological obstructions to group stability

I will give an introductory talk with the aim of describing primary cohomological obstructions to group stability. I will discuss two complementary approaches: one based on the approximate monodromy correspondence of Connes, Gromov and Moscovici, and the other, on which I will focus more closely, relying on Kasparov’s KK-theory combined with finite dimensional approximation properties of group C*-algebras.

OGGW04 - Stability and probabilistic methods

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Tue 25 Nov 14:00: Stability, residual finiteness and lots of examples OGGW04 - Stability and probabilistic methods

School of Physical Sciences - 3 hours 25 min ago
Stability, residual finiteness and lots of examples

I will give an introductory talk with the aim of describing primary cohomological obstructions to group stability. I will discuss two complementary approaches: one based on the approximate monodromy correspondence of Connes, Gromov and Moscovici, and the other, on which I will focus more closely, relying on Kasparov’s KK-theory combined with finite dimensional approximation properties of group C*-algebras.

OGGW04 - Stability and probabilistic methods

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Fri 21 Nov 14:00: On the sample complexity of multi-objective learning

School of Physical Sciences - Sun, 16/11/2025 - 20:03
On the sample complexity of multi-objective learning

In multi-objective learning (MOL), several possibly competing prediction tasks must be solved jointly by a single model. Achieving good trade-offs may require a model class G with larger capacity than what is necessary for solving the individual tasks. This, in turn, increases the statistical cost, as reflected in known MOL bounds that depend on the complexity of G. We show that this cost is unavoidable for some losses, even in an idealized semi-supervised setting, where the learner has access to the Bayes-optimal solutions for the individual tasks as well as the marginal distributions over the covariates. On the other hand, for objectives defined with Bregman losses, we prove that the complexity of G may come into play only in terms of unlabeled data. Concretely, we establish sample complexity upper bounds, showing precisely when and how unlabeled data can significantly alleviate the need for labeled data. These rates are achieved by a simple, semi-supervised algorithm via pseudo-labeling.

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Wed 03 Dec 13:30: Short character sums evaluated at homogeneous polynomials

School of Physical Sciences - Sat, 15/11/2025 - 06:58
Short character sums evaluated at homogeneous polynomials

Let p be a prime. Bounding short Dirichlet character sums is a classical problem in analytic number theory, and the celebrated work of Burgess provides nontrivial bounds for sums as short as p1/4+ε for all ε>0. In this talk, we will first survey known bounds in the original and generalized settings. Then we discuss the so-called ``Burgess method’’ and present new results that rely on bounds on the multiplicative energy of certain sets in products of finite fields.

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Wed 19 Nov 16:00: Symplectic groups and Cobordism categories

School of Physical Sciences - Fri, 14/11/2025 - 18:34
Symplectic groups and Cobordism categories

In joint work with Land and Nikolaus, we recently computed a large part of the stable cohomology of symplectic groups over the integers. In the talk I will try to explain our approach highlighting two perhaps surprising facts: That we import surgery techniques from differential topology and that it is necessary to include derived symplectic forms to facilitate this.

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Mon 08 Dec 09:30: translation invariant defects in two dimensions and integrable perturbations BIDW03 - The Many Faces of Boundaries, Impurities, and Defects

School of Physical Sciences - Fri, 14/11/2025 - 18:30
translation invariant defects in two dimensions and integrable perturbations

We consider translation invariant defects in two dimensions and their properties. Two classes of such defects are operators implementing generalised Gibbs ensembles (GGEs), and chiral perturbations of topological defects. We investigate non-local charges for perturbations of two-dimensional conformal field theories that arise as chiral perturbations in this way. We find solutions for a wide range of perturbations including the well-known (1,2), (1,3) and (1,5) integrable perturbations of Virasoro minimal models (with associated local conserved charges), but we also find solutions for other bulk perturbations, such as (1,7), and we contrast this with the (non) existence of local conserved charges. Based on work with F Ambrosino, M Downing, F Karimi, A Konechny, I Runkel, T Sengupta and A Sudhakar.

BIDW03 - The Many Faces of Boundaries, Impurities, and Defects

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Fri 21 Nov 16:00: Topological Portals to the Dark Sector

School of Physical Sciences - Fri, 14/11/2025 - 16:36
Topological Portals to the Dark Sector

I will present the construction and phenomenology of novel portals between the Standard Model and dark sectors, arising from topological operators in chiral perturbation theory. The first example is based on a mixed Wess–Zumino–Witten term that uniquely connects three QCD pions to two dark pions, leading to a consistent framework for light thermal inelastic dark matter with suppressed direct and indirect detection, but distinctive collider signatures. The second example is a minimal model in which gauging the topological Skyrme current naturally links a QCD -like dark sector to the Standard Model, allowing a semi-annihilation process that sets the relic abundance. The purely p-wave nature of these interactions ensures compatibility with existing constraints while offering discovery prospects at colliders and beam-dump experiments.

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