Seminars this semester

16:00

The generalised Mukai conjecture for spherical varieties

Hicks Seminar Room J11

Abstract:
The generalised Mukai conjecture (GMC) concerns the characterisation of powers of projective space among Fano varieties. In this talk, we will prove the GMC for spherical varieties. These varieties generalise toric varieties, and their geometry may be interpreted combinatorially via a 'spherical dictionary'. If time permits, we will explain how this result can be extended to prove a purely combinatorial smoothness criterion for spherical varieties.

Jan 30

Thu

Alex Pietrow (Leibniz Institute for Astrophysics Potsdam - AIP, Germany)

10:00

Sun-as-a-star flare observations with HARPS-N and SST

Abstract:
Stellar flares cannot be spatially resolved, which means that we have to extract complex three-dimensional behavior from a one-dimensional disk-integrated spectrum. Due to their proximity to Earth, solar flares can serve as a stepping stone for understanding their stellar counterparts, especially when using a Sun-as-a-star instrument in combination with spatially resolved observations. In this talk I will discuss a confined X2.2 flare and its eruptive X9.3 successor as measured by the HARPS-N Sun-as-a-star telescope. The behavior of multiple photospheric and chromospheric spectral lines are investigated by means of activity indices and contrast profiles, which are then related to physical processes directly observed in high-resolution observations made with the Swedish 1-meter Solar Telescope (SST). We further explore these relations by using the newly developed Numerical Sun-as-a-Star Integrator (NESSI) code to convert high-resolution SST flares to full disk spectra. Our findings suggest a relationship between the evolving shapes of the disk integrated spectra and the flare locations on the solar disk, which could be act as a guide for constraining flare locations in stellar spectra.

Jan 31

Fri

Barworth Agriculture (https://www.kehubmaths.co.uk/triage-workshops/)

10:00

Soil sampling at a field scale for crop pests

https://tinyurl.com/raxmyf4y

Abstract:
Potato cyst nematode (PCN) is an endemic pest found in potato growing regions around the world. Crucial agronomic management decisions are made pertaining to the establishment of a potato crop based on the results of a field survey for the pest. For each sample, current practice is to amalgamate around 40 soil cores collected in either a regular grid pattern or at randomised GPS points generated by a computer algorithm. The current recommended area for each composite sample is one hectare. Soil samples can be as small as 100g, and as PCN are very small (<1mm), they can easily be missed using industry standard sampling methods. Our challenge is to improve soil sampling strategy such that more PCN is detected. One factor that could be considered is decreasing the sampling area (for example, from one hectare to a quarter hectare), but in practice, this option is not attractive to field owners since the cost for taking and processing a sample remains the same, independent of the area size. Ideally, we would like to understand the likelihood of retrieving the target organism when the diameter or number of cores taken per area is varied. Much work has been done on attempting to model the ‘typical’ field distribution of PCN, but unfortunately there is a wide range of environmental and biological factors that undermine any model based on real field distribution data. Instead, a matrix that compares the likelihood of detecting PCN based on theoretical population distributions would be helpful.

Feb 5

Wed

Robert Rogers (Sheffield)

Algebraic Geometry Seminar

16:00

Moduli of Quiver Representations and GIT Quotients

Hicks Seminar Room J11

Abstract:
In this talk we will discuss the notion of a quiver and its applications to algebraic geometry. In particular we will construct moduli spaces of quiver representations and stability conditions on quivers. We will show how to construct some simple GIT quotients from this data. Along the way Gabriel's theorem and Mumford's criterion will be covered.

Feb 6

Thu

Spectral Sequences Reading Group

13:00

Hicks Seminar Room J11

Feb 10

Mon

Michael Wemyss (Glasgow)

14:00

The classification of 3-fold flops

Hicks Seminar Room J11

Abstract:
I will overview the analytic classification of smooth, simple, 3-fold flops. There are three main aspects: (1) the theoretical advances that reduce the problem to classification of a certain class of noncommutative finite dimensional algebras, (2) a complete understanding of those algebras, then lastly (3) building the associated geometry for each algebra in that class. In the process of proving these results, we also obtain various bonus (and very surprising) geometric corollaries, including to curve-counting invariants, and also to 3-fold crepant divisor-to-curve contractions. Part (1) is joint with Joe Karmazyn and Emma Lepri, the remainder is joint with Gavin Brown.

Feb 11

Tue

Fraser Sparks (Nottingham)

16:00

A (very) brief introduction to motives

Hicks Seminar Room J11

Abstract:
(Co)homology theories are ubiquitous throughout pure mathematics. Can we find some objects which `capture’ the (co)homological behaviour of our spaces of interest? In algebraic geometry, the answer is the theory of motives. They allow one to use topological methods in the context of algebraic geometry, and can be thought of as a `universal cohomology theory’ for varieties. In this talk I will give a brief introduction to the theory, highlighting the analogies with topology, and I’ll also discuss some applications.

Feb 12

Wed

Christian Lehn (Bochum)

14:00

Tannakian groups of perverse sheaves and E6 geometry

Hicks Seminar Room J11

Feb 12

Wed

Lei Zu (NCBJ Warsaw)

15:00

Probing Dark Matter Non-gravitational Interactions with Weak Lensing Surveys

F20

Abstract:
Modern cosmological surveys, with their unprecedented precision, have established weak lensing as a powerful probe of the matter distribution in the universe, enabling us to test the nature of dark matter (DM) interactions. The talk will briefly introduce this topic and present our recent investigation of weak lensing constraints on DM interactions with baryons and neutrinos. We utilize cosmological N-body simulations to model the nonlinear evolution of structure formation on weak lensing scales (k ~ 0.1–1 h/Mpc). To efficiently explore the parameter space of cosmological models, we have developed a novel numerical method that facilitates the use of simulation results. Our analysis of DES Year 3 data reveals significant constraints on DM-proton scattering, improving upon previous constraints from cosmic microwave background (CMB) data by up to a factor of five. Furthermore, our analysis of cosmic shear data reveals an intriguing ~3σ hint of a non-vanishing DM-neutrino interaction, which strengthens similar previous findings in high-multipole CMB and Lyman-α forest data. We also discuss how this interaction could simultaneously ameliorate the persisting S8 tension.

Feb 12

Wed

Francesco Denisi

15:30

MMP for Enriques pairs and singular Enriques varieties

Hicks Seminar Room J11

Feb 12

Wed

Dominique Mattei (Hannover)

17:00

Twisting Lagrangian fibrations

Hicks Seminar Room J11

Feb 13

Thu

Ignacio Barros (Antwerp)

09:30

Geometric theta correspondence and extremal divisors on moduli spaces of K3 surfaces

Hicks Seminar Room J11

Feb 13

Thu

Jaroslav Dudík (Astronomical Institute of the Czech Academy of Sciences, ASU (CZ))

10:00

Three dimensional magnetic reconnection: Theory and observations

Abstract:
In the recent decades, three-dimensional modelling of solar flares and eruptions has made a number of predictions that were subsequently indicated by high-resolution imaging observations. These include existence of magnetic reconnection geometries involving the erupting flux rope itself, which drifts as a result, and also the apparent slipping and slip-running motion of footpoints of individual reconnecting structures. In this talk, we will summarize the predictions of the MHD models as well as the corroborating evidence, with particular emphasis on recent observations of super-Alfvénic slippage of flare kernels.

Feb 13

Thu

Franco Giovenzana (Paris)

11:00

On the Projective Duality of Kummer Fourfolds and Their Equations

Hicks Seminar Room J11

Feb 13

Thu

Alessio Bottini (Bonn)

14:00

A modular construction of OG10

Hicks Seminar Room J11

Feb 13

Thu

Claudio Onorati (Bologna)

15:30

Schur functors and modular bundles

Hicks Seminar Room J11

Feb 13

Thu

Igor Sikora (Krakow University of Economics)

16:00

Hicks LT11

Feb 13

Thu

Reinder Meinsma (Brussels)

17:00

Derived equivalence for moduli spaces of sheaves on K3 surfaces

Hicks Seminar Room J11

Feb 14

Fri

Yajnaseni Dutta (Leiden)

09:15

The relative intermediate Jacobian

Hicks Seminar Room J11

Feb 14

Fri

The Access Group (https://www.kehubmaths.co.uk/triage-workshops/)

10:00

Linkage of Hierarchical Data

https://tinyurl.com/vzas23se

Abstract:
Suppose you wanted to match individuals in Dataset 1 to individuals in Dataset 2. The individuals in both datasets have various identifying features – first name, last name, email, phone number, address. These features may be missing in either set, and also may have errors or differences. There is no training data. Matching individuals between the two sets is a standard problem in data linkage, and there are various standard methods which may be rule based or probabilistic or some combination of the two. Now consider that in addition, Datasets 1 and 2 record parent-child relationships between individuals. Again, the recorded relationships may be missing or incorrect. Also, of course, not all individuals are in both datasets, so a recorded parent-child relationship in Dataset 1 may be missing either the parent or the child (as well as of course the relationship) in Dataset 2, or vice versa. What is the best way to incorporate this relationship data into either rule-based or probabilistic linkage?

Feb 14

Fri

Andrey Soldatenkov (Campinas)

10:30

Metric structures on degenerate twistor families

Hicks Seminar Room J11

Feb 14

Fri

Yoonjoo Kim (Columbia)

12:00

The Néron model of a Lagrangian fibration

Hicks Seminar Room J11

Feb 17

Mon

Dr Anastasia Kadochnikova (University of Nottingham)

15:00

Forward and inverse problems in the analysis of biological data.

LT9, Hicks / Google Meet

Abstract:
Despite the ever-increasing volume of high-resolution biological data, its analysis remains strongly grounded in first principles, as our goal is to gain insight into the underlying mechanisms that generate the data. Thus, the investigation of biological data often employs mechanistic mathematical models. Two main challenges in developing a mechanistic model are parametrisation (the forward problem) and calibration against the observed data (the inverse problem). Though these two tasks must be addressed on a case-by-case basis, there are common steps that can be taken to streamline the modelling process across various scenarios. In this talk, we will consider three case studies that highlight different aspects of model development for biological systems. The first study focuses on cellular biology, where a Hidden Markov Model is developed to infer hidden variables from the observed data. The second study, set in the microbiology domain, is an example of developing a dynamical model completely from first principles in anticipation of the experimental data against which the model will be calibrated. The third study, related to cardiac electrophysiology, involves building a dynamical model that incorporates experimentally observed ratios as its parameters. Through these examples, we will attempt to summarise common practices of model synthesis for biological systems. Additionally, we will discuss the challenges and advantages of engaging with the domain specialists during model development, methods of assessing the model quality, and examples of dealing with messy data.

Feb 19

Wed

Adam Smith (Sheffield)

15:00

Axion-dilaton interactions in the dark sector

Hicks Seminar Room J11

Abstract:
Axion-dilaton models provide a well-motivated, minimal class of models for which kinetic interactions between multiple scalar fields and their predictions can be explored, in particular in late time cosmology. I will review this class of models and present the formalism we developed for studying kinetic interactions between rapidly oscillating axion fields and their dilaton partners on cosmological scales. I will then show how this formalism can be used to study two cases of phenomenological interest. Firstly, the cosmological implications of prescribing an axion and a dilaton field to describe dark matter and dark energy, respectively, along with the predicted interactions with other cosmological species. Secondly, the implications of allowing an axion field to couple to multiple species of matter and how this can be used to build early dark energy theories compatible with novel multi-field screening mechanisms.

Feb 19

Wed

Lily Bennett (Sheffield)

16:00

Pontryagin Duality for Semilattices

Hicks Seminar Room J11

Abstract:
In this talk we discuss the duality of the category of discrete semilattices and the category of compact zero-dimensional semilattices, introduced by Hofmann, Mislove and Stralka in the 1970s. We start by taking a brief look at semilattices and compact zero-dimensional semilattices, before moving on to look at diagram categories and the notion of categorical density. Finally, we use this categorical machinery to provide an outline of the argument for duality.

Feb 20

Thu

Clover May (NTNU)

16:00

Hicks Seminar Room J11

Feb 25

Tue

Alex Torzewski (Kings)

14:00

How common is Galois complex multiplication?

Hicks Seminar Room J11 / Google Meet

Abstract:
An elliptic curve over a characteristic zero field is said to have complex multiplication when its endomorphism ring is larger than Z ("E has extra endomorphisms"). Generic elliptic curves don't have complex multiplication. Similarly, when the Tate module of E has extra endomorphisms we say E has "Galois" complex multiplication. Over a number field, E has Galois complex multiplication if and only if it has complex multiplication. Over a local field this need not be the case. We investigate how often this happens via basic computations in p-adic Hodge theory.

Feb 26

Wed

Jacob Thompson (Sheffield)

15:00

Quantum corrected anti-de Sitter spacetime: backreaction from the RSET (and a little bit of RKT)

Hicks Seminar Room J11

Abstract:
The question on a lot of theoretical physicists’ minds at the moment is, when is the next coffee break? And to a lesser extent, how do we connect quantum mechanics with general relativity and have a fully self-consistent theory of quantum gravity? Quantum field theory on curved spacetimes, a semi-classical theory, is one such approach. This describes how quantum fields (modelled by a renormalised stress-energy tensor) behave on classical curved backgrounds. In this talk I will outline how this approach works and what role backreaction - required for a fully self-consistent theory - plays. I will also describe an approximation to full semi-classical gravity, quantum corrections, and present some results on three- and four-dimensional anti-de Sitter spacetime for the massless, conformally coupled scalar field. I will additionally show some preliminary results for a relativistic kinetic theory (RKT) approach where matter is modelled as a classical gas of particles, and how we have used this as an approximation to the RSET on the RHS of the semi-classical Einstein equations.

Feb 26

Wed

N/A

15:00

Enriched duality in double categories 1

Hicks LT9

Abstract:
We will discuss Vasilakopoulou's paper up the end of Section 2.3.

Feb 26

Wed

Jingxiang Ma (Sheffield)

16:00

Counting rational curves in the projective plane

Hicks Seminar Room J11

Abstract:
I will talk about a classical problem in enumerative geometry. We start with special cases that can be solved using elementary geometric arguments. We then move to the modern approach which solves the general problem, where the key idea is to understand these curve counts as Gromov-Witten invariants.

Feb 27

Thu

Augustin André-Hoffmann (Univ of Sheffield, MPS (UK))

10:00

How BRADPIT could help us in flare forecasting through small AR activity monitoring

Abstract:
The Sun is a dynamic star, displaying activities ranging from subtle, short-lived events to major coronal mass ejections (CMEs) and powerful flares. Differentiating between “flaring” and “non-flaring” active region (AR) configurations is critical for heliophysics research. This study investigates whether small to medium-scale activity in ARs holds clues about their eruptive potential and future behaviour. Using data from the Atmospheric Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO), we analyse transient brightenings and their relationship to the magnetic polarity inversion line (PIL) in ARs. We observe significant differences between pre-flaring and non-flaring ARs in terms of the spatial distribution and temporal evolution of transient brightenings around the PIL. Key parameters include the number, intensity, and magnetic flux of brightenings over time, as well as their behaviour across multiple wavelengths. These variations offer insights into the Sun's atmospheric dynamics and the mechanisms driving major flares and – in case of coronal mass ejections – eruptions. By understanding the pre-eruptive activity in ARs, we aim to improve solar event prediction capabilities and advance our knowledge of the relevant dynamics.

Feb 27

Thu

Alexander Pietrow (Leibniz Institute for Astrophysics, Potsdam)

Plasma Dynamics Group

16:00

Sun-as-a-star flare observations with high-resolution telescopes

online / meet.google.com/rso-peaf-hse

Abstract:
Stellar flares cannot be spatially resolved, meaning we have to extract complex three-dimensional behavior from a one-dimensional disk-integrated spectral timeseries. Due to their proximity to Earth, solar flares can serve as a stepping stone for understanding their stellar counterparts, especially when using a Sun-as-a-star instrument in combination with spatially resolved observations including some large IRIS flares. In this talk, I will discuss how high-resolution observations with a limited field-of-view can be converted into approximations of disk-integrated spectra using the newly developed Numerical Sun-as-a-Star Integrator (NESSI). Additionally, I will discuss the impact of projectional effects on the study of such events with focus on the detection of coronal mass ejections. Our findings suggest common patterns in the disk-integrated spectra between flares of different strengths and locations that can be used to better interpret stellar flares without resolved context.

Feb 28

Fri

Datasparq (https://www.kehubmaths.co.uk/triage-workshops/)

Probability in the North East

10:00

Evaluating performance of pricing models for constrained products with finite selling periods

https://tinyurl.com/mntv5jd9

Abstract:
In industries where products expire after a long selling period, often spanning 100 days or more, evaluating the impact of a new pricing strategy is particularly challenging due to fluctuating, seasonal patterns of demand across the extended sales cycle. Traditional A/B testing or other conventional methods of evaluation would typically require waiting for the entire sales period to complete before drawing conclusions, which can be a significant disadvantage when rapid feedback is necessary to optimise strategy and improve performance. An extended test can be undesirable and costly for the business if the strategy underperforms. How can we develop an efficient evaluation framework that provides an accurate assessment of a pricing strategy’s effectiveness in the shortest time possible?

Mar 4

Tue

Various

08:00

Hicks Seminar Room J11

Mar 4

Tue

Various

Probability in the North East

09:00

Mar 4

Tue

Jens Funke (Durham)

14:00

Indefinite theta series via incomplete theta integrals

Hicks Seminar Room J11 / Google Meet

Abstract:
Positive definite theta series have been a classical tool in the arithmetic of quadratic forms and also in the theory of modular forms. In comparison, the indefinite case has been less studied. In this talk we will explain how indefinite theta series naturally arise in the context of symmetric spaces of orthogonal type and discuss recent developments inspired by mathematical physics. This is joint work with Steve Kudla.

Mar 4

Tue

14:00

Enriched duality in double categories 2

Mar 5

Wed

Benito Juárez Aubry (York)

15:00

Advances and challenges in semiclassical gravity

Hicks Seminar Room J11

Abstract:
Semiclassical gravity offers a description of the semiclassical regime of quantum gravity, in which quantum matter sources the Einstein field equation through the expectation value of the matter fields' stress-energy tensor, while the quantum fields propagate in the spacetime they curve. In this talk, I will briefly review the status of this theory, including some challenges and advances. Amongst the advances, I will discuss what we understand in terms of exact solutions to the theory. I will also discuss the role of strong cosmic censorship in semiclassical gravity and how it prevents information loss in black hole evaporation. Finally I will discuss some conceptual difficulties and tensions and propose new avenues to explore to get a better grasp of these problems.

Mar 5

Wed

Pierre-Louis Guillot (Sheffield)

16:00

The G-construction : an un-delooped construction for algebraic K-theory

Hicks Seminar Room J11

Abstract:
We will introduce constructions for algebraic K-theory that have the property of being un-delooped -- meaning that they provide simplicial objects whose homotopy groups correspond to the K-groups with no shift in degree. We will see how they can be constructed with increasing generality, and applied to categories with increasingly weak "additivity conditions". The goal is to try to engage with ideas contained in models for algebraic K-theory and try to get a feeling for why these " additivity conditions " matter.

Mar 6

Thu

Neil Strickland (Sheffield)

Frobenius manifolds and Quantum cohomology

16:00

THH of truncated Brown-Peterson spectra and related invariants

Hicks Seminar Room J11

Mar 7

Fri

Evgeny Shinder (Sheffield)

02:00

Why should we study Frobenius manifolds?

Hicks Seminar Room J11

Mar 10

Mon

Jenya Tevelev (Massachusetts at Amherst)

Algebraic Geometry Seminar

14:00

Semi-orthogonal decompositions of Fano varieties and moduli spaces

Hicks Seminar Room J11

Abstract:
The study of fully faithful functors, including equivalences, between derived categories of smooth projective varieties (or, more generally, smooth proper triangulated categories) is, in many ways, analogous to the study of rational contractions in the minimal model program. For a Fano manifold, homological mirror symmetry predicts that its derived category admits canonical semi-orthogonal decompositions (related by the braid group action) with remarkable properties, such as compatibility with rational contractions. After discussing this motivation, I will survey potential constructions of canonical semi-orthogonal decompositions, focusing on the case where the Fano manifold is a moduli space of stable objects of some type on another manifold and where its birational geometry can be understood as a variation of the stability condition. As an application, we will construct the canonical semi-orthogonal decomposition of the derived category of the moduli space of stable vector bundles of rank 2 with a fixed determinant of odd degree on a smooth projective curve. When the degree is even, the moduli space is singular, and the construction provides canonical semi-orthogonal decompositions of its quasi-BPS categories; for example, they are compatible with the Hecke correspondence.

Mar 10

Mon

Anna Leathard (Chemical, Biological and Materials Engineering, University of Sheffield)

15:00

Design and Control of Emergent Dynamics in Enzymatic Reaction Networks

LT7

Abstract:
Over the last fifty years, the interdisciplinary area of nonlinear chemical dynamics has significantly expanded, characterised by a cooperative interplay between theory and experiment. These systems display a wide range of behaviours, including sudden shifts in stability and the emergence of intricate patterns that cannot be captured by linear mathematics alone. In chemical systems, such non-linearities often stem from mass action kinetics, particularly in reactions far from equilibrium. This research develops numerical kinetic models of enzyme systems to explore how system design, confinement, feedback, and mass transport influence biochemical rhythms and other interesting phenomena. \vspace{0.1em}
Bio: Anna is a fourth-year PhD student in Chemical, Biological and Materials Engineering at the University of Sheffield, supervised by Professor Annette Taylor. Her research focuses on numerical modelling of enzyme-based systems, exploring interesting dynamics through reaction kinetics and transport processes. She is part of a Leverhulme Trust-funded collaboration with the University of Leeds, with interests in integrating experiments and kinetic modelling for applications in artificial cells, materials science, drug delivery, and sensing.

Mar 10

Mon

James Salsbury (Sheffield, Mathematical and Physical Sciences)

15:00

Probability of Success Methods in Clinical Trial Design

LT7

Abstract:
When designing a clinical trial, the sample size must be carefully planned to ensure reliable results. If too few patients are enrolled, the trial may lack sufficient statistical power to demonstrate the treatment’s efficacy. Conversely, enrolling too many patients may expose them to unnecessary risks and increase costs. Traditionally, sample size determination relies on the statistical concept of ‘power,’ which assumes that the treatment has the expected effect. However, this assumption may not always hold. We introduce an alternative approach, the ‘Probability of Success’ method, which accounts for uncertainty in clinical trial design.

Bio: James Salsbury is a fourth year statistics PhD student at the University of Sheffield, supervised by Professors Jeremy Oakley, Steven Julious and Dr Lisa Hampson. His PhD is in collaboration with Novartis [a pharmaceutical company], looking at probability of success calculations for survival trials. His interests lie in Bayesian statistics, in particular eliciting prior distributions from experts and quantitative decision-making.

Mar 11

Tue

14:00

Enriched duality in double categories 3

LT9

Mar 12

Wed

Laura Iacconi (Queen Mary)

15:00

Mapping inflationary loop corrections to boundary terms

Hicks Seminar Room J11

Abstract:
Both single- and multi-field models of inflation might lead to enhanced scalar fluctuations on scales much smaller than those seeding the large-scale structure formation. In these scenarios, it is possible that the spike of power at high wavenumber might induce large corrections to the scalar power spectrum, e.g. in the form of loop corrections, potentially endangering the perturbativity of the underlying models. In this talk we discuss recent developments in the calculation of the 1-loop correction to a large-scale adiabatic mode. We demonstrate that non-volume-suppressed corrections only contribute at the boundaries of the momentum integral. To achieve this we employ expansion methods, such as the $\delta N$ formalism, as well as more general expansions that do not rely on assumption of validity of the separate universe picture.

Mar 13

Thu

Yara De Leo (INAF – Catania Astrophysical Observatory, Italy)

10:00

Two Distinct Eruptive Events Observed by Metis on October 28, 2021

Abstract:
On October 28, 2021 the first X-class solar flare of Solar Cycle 25 occurred in active region NOAA AR 12887 with a peak at 15:35 UT. It produced the rare event of ground-level enhancement of the solar relativistic proton flux and a global extreme ultraviolet wave, along with a fast halo coronal mass ejection (CME) as seen from Earth’s perspective. A few hours before the flare, a slower CME had erupted from a quiet Sun region just behind the northwestern solar limb. Solar Orbiter was almost aligned with the Sun-Earth line and, during a synoptic campaign, its coronagraph Metis detected the two CME events in both Visible Light (VL) and UltraViolet (UV) channels. The earlier CME took place in the north-west (NW) sector of Metis field of view, while several bright features of the flare-related event appeared mostly to the south-east (SE). The NW and SE events have two distinct origins, but were both characterized by a very bright emission in HI Ly-alpha visible in the UV images of Metis up to 8 solar radii. This work is a follow-up study of two out of the six events analyzed by Russano et al. 2024 (A&A, 683, A191), aimed at investigating the evolution of these two almost co-temporal CMEs but originating in such distinct source regions. To that end, we extensively inspect data sets from numerous remote-sensing instruments observing the Sun in several spatial and spectral regimes. We characterize several aspects of these CMEs, including their three-dimensional properties, kinematics, mass, and temporal evolution of those quantities. Results of this work point to notable differences between these two events showing significant UV emission in the corona.

Mar 13

Thu

Daniel Luckhardt (Sheffield)

Office for National Statistics

16:00

The Giry monad revisited

Hicks Seminar Room J11

Abstract:
For over 40 years the Giry monad has been an object of intense investigations plagued by difficulties. Typically---as already done by Giry—the monad is restricted to specific classes of topological spaces to achieve tractability. In this talk we will return to a $\sigma$-algebra as the only structure and carefully analyse, how the monad can be restricted, while still covering all cases relevant for real-world application. Again---as for Giry---limit preservation properties will serve as a touchstone. Unlike Giry we obtain also result on weak pullback preservation. Moreover the journey will lead us ward the boundaries of ZCF and beyond.

Mar 14

Fri

10:00

Reliable confidence intervals for proportions in the UK Annual Population Survey

https://tinyurl.com/5n8yc8y9

Abstract:
The ONS compiles the Annual Population Survey (APS) based on surveying households across the UK. It provides quarterly snapshots for key labour market statistics such as official employment figures, job characteristics and work-related education. Government departments, public bodies and charities use this survey extensively for policy making and research. There is increasing user demand for data disaggregated by demography and geography, and this exacerbates difficulties in calculating uncertainties for estimates due to small subpopulation sample sizes. Improvements to the estimates and their uncertainties can therefore have significant public impact. We are specifically interested in validating methodology for computing confidence intervals (CIs) for small and large proportions in the APS. For simple random samples (SRS), several well-established methods are available, such as the Wald, Wilson or Clopper-Pearson CIs. However, for surveys such as the APS with complex sample designs including, for example, stratification, clustering or longitudinal elements, this is still an area of active research. A common strategy consists in adapting the SRS approaches by introducing an effective sample size which incorporates the impact of the sample design on precision. Unfortunately, the literature disagrees on how to estimate the effective sample size, and the optimal approach may depend on the specific survey design. We therefore aim to develop a CI method appropriate for the APS and validate its performance. This could be approached through simulated samples based on suitably simplified versions of the APS sample design. Further aspects requiring more research concern CIs for sample subgroups and accounting for a calibration stage within survey weighting.

Mar 18

Tue

Elena Collacciani (Padova)

14:00

Hicks Seminar Room J11 / Google Meet

Mar 18

Tue

14:00

Enriched duality in double categories 4

**F35**

Mar 19

Wed

Jens Chluba (Manchester)

15:00

CMB spectral distortion science beyond the monopole

Hicks Seminar Room J11

Abstract:
CMB spectral distortions have now been recognized as an important new probe in cosmology. However, most of the science has focused on CMB monopole distortions. In my talk, I will give a brief update on the status of CMB spectral distortions and then explain how it has now become possible to compute the full spectro-spatial evolution of the CMB including distortions. Anisotropic distortion signals do not require an absolute calibration and can be constrained with Planck, Litebird, CMB-S4 and the SKA, opening yet another way to study the primordial universe.

Mar 20

Thu

Andrew Fisher (Sheffield)

16:00

Hicks Seminar Room J11

Mar 24

Mon

Joshua Berry (Chemical, Biological and Materials Engineering, Sheffield)

15:00

Machine Learning and Artificial Intelligence Towards Better Engineering Materials

LT7

Abstract:
Metallic alloys are the cornerstone of modern industry, driving everything from transport in the aerospace and automotive industries, to energy generation, healthcare and beyond. The continuous development of new alloys is essential for improving performance in service and enabling future technologies. However, alloy development remains a long, costly, and iterative process with limited adaptability. Machine learning presents an opportunity to accelerate and reduce the cost of alloy discovery. In the first part of this talk, we’ll explore how machine learning can drive the discovery of novel hard metal alloys, providing a step change in the design cycle. Despite this, a key limitation in applying machine learning to alloy design is the lack of sufficiently large and high-quality datasets. While extensive experimental data exists in the scientific literature, it is often scattered and unstructured, making it difficult to leverage for computational analysis. To address this challenge, the second part of this talk will discuss leveraging large language models (LLMs) and natural language processing (NLP) to extract, curate, and construct alloy property databases directly from published research. Performing a comparative analysis between manually curated datasets and those generated through LLM-driven literature mining, evaluating the challenges and opportunities of automated data extraction for materials informatics. By integrating machine learning-driven alloy design with automated literature-based data extraction, this research aims to facilitate the development of comprehensive databases, ultimately accelerating alloy discovery and enhancing the effectiveness of computational materials design.

Bio: I am an experimental physicist by background, holding a master's degree in physics from the University of Sheffield before transitioning into material science. My PhD at the University of Sheffield focussed on materials informatics and alloy design, where I collaborated with the AIRE team in the computer science department, working at the intersection of material science and data-driven methodologies. Currently I am a postdoctoral research associate at the University of Sheffield, specialising in powder feedstock recycling and reconditioning to enhance the sustainability of industry manufacturing by reducing its environmental footprint.

Mar 24

Mon

Daniel M Chaib (Sheffield Methods Institute (SMI))

15:00

Constructing a Measure of Cultural Participation for Young Carers

LT7

Abstract:
What did you do at the end of the school day? Would you go to a sports club with friends? Or go to the cinema with your family? Or perhaps you needed to go home to cook and clean for a loved one? In this paper I look at exactly that, constructing a model of cultural participation for children with and without caring roles. Childhood cultural participation is linked to beneficial outcomes in one's educational attainment, employment and wider opportunities. Despite this, current literature is scarce of inquiry into the impacts of cultural participation on children. Additionally, young carers occupy a precarious position within the youth demographic, as their informal caring responsibilities take time and energy from other aspects of their lives. In this seminar, I will give a deep dive into my implementation of confirmatory factor analysis to construct a model of cultural participation of children. Further, I give critiques of PCA and aggregate measures to best justify the use of CFA. However, despite the value of exploring cultural participation for children with and without caring responsibilities using this methodology, we also need to be aware of its restrictions. With this in mind, I’ll also talk about data limitations I’ve experienced in building this model, and the drawbacks this has on building factors that entirely encompass different facets of cultural participation

Bio: I’m a PhD student in the Sheffield Methods Institute (SMI), researching outcomes of Young Carers. Through this, I’m very grateful to be partnered with Sheffield Young Carers, who have been amazing throughout! Previously, I’ve completed a Masters in Clinical Research and a Bachelors in Maths and Economics, both also from the University of Sheffield. Previous work as a mentor for young people, in addition to being part of student focused research projects has helped further in situating me in the Young Carer research space.

Mar 25

Tue

Rose Berry (UEA)

14:00

Hicks Seminar Room J11 / Google Meet

Mar 25

Tue