Events

Mathematical model of sexual response
Speaker: Dr Konstantin Blyuss, University of Sussex, UK
Date: 7 March 2023
Abstract: In this talk I will discuss a mathematical model of Masters-Johnson human sexual response cycle. As a starting point, I will review cusp catastrophe and will show why earlier studies that interpreted sexual response cycle using this catastrophe were incorrect. I will then present a derivation of a phenomenological psycho-physiological model of human sexual response cycle. Bifurcation analysis is performed to identify stability properties of the model’s steady state, and numerical simulations are performed to illustrated different types of dynamics associated with the cycle. We will then look at the stochastic version of the model, where I will discuss properties of the spectrum and variance of stochastic oscillations around deterministically stable steady state, as well as the computation of confidence regions. To make a better understanding of stochastic dynamics, I will show how large deviation theory can be used to compute optimal escape paths from the neighbourhood of the steady state, and will discuss clinical implications of results.

TBA (Discussion)
Speaker: Prof. Lorenzo Fioramonti, Surrey Institute for Sustainability, University of Surrey, UK
Date: 21 February 2023

A talk of two halves:  “Practical catastrophe theory”, and “Hidden dynamics of maps and sleep cycles”
Speaker: Dr Mike Jeffrey, University of Bristol
Date: 7 February 2023
Abstract: During covid I did the unusual thing of discovering something that might actually be useful. Actually two things, so I’d like to present them both briefly. One concerns how to handle discontinuities in maps, and one concerns how we locate bifurcations in (also unusually for me) smooth dynamical systems. I’ll give examples taken from reaction-diffusion PDEs in part 1 (Practical catastrophe theory for the modern age), and from sleep-wake cycle maps in part 2 (Hidden dynamics of maps and sleep cycles, and when “period 1+2 implies chaos”)

Modelling dryland vegetation patterns: the impact of non-local seed dispersal and mechanisms of species coexistence
Speaker: Dr Lukas Eigentler, University of Bielefeld, Germany
Date: 27 January 2023

Geometric singular perturbation analysis of the multiple-timescale Hodgkin-Huxley equations
Speaker: Dr Panos Kaklamoanos,  Maxwell Institute for Mathematical Sciences, University of Edinburgh
Date: 17 January 2023

Accommodating data structure in clinical trials and other applied studies. 
Speaker: Professor Simon Skene, Professor of Medical Statistics and Director of Surrey Clinical Trials Unit

Date: 6 December 2022

Modelling in early discovery for large molecules
Speaker: Dr Adam Nasim, GSK
Date: 15 November 2022

Open quantum dynamics for plant motions
Speaker: Professor Dorje Brody, Department of Mathematics, Surrey
Date: 25 October 2022

Computational modelling of neural dynamics: From basic principles to biomedical research
Speaker: Dr Roman Bauer
Date: Thursday 10 December 2020
Abstract: The development of the brain is a highly complex process, involving various mechanisms on different spatial and temporal scales.

While technological advances have allowed to extract valuable information from the brain, the complex nature of these data renders it often challenging to compare and validate theoretical concepts. However, a better understanding of changes during brain development could help elucidate driving factors of disorders, as well as give rise to potential treatment strategies.

Here, I will present some lines of work where computational modelling and analysis is used to study changes in neural tissue during brain development and degeneration. These changes range from axonal arborizations on the single neuron level to inter-areal fibre tracts on the scale of large populations of neurons. Notably, several characteristics associated with pathological conditions can be reproduced, establishing a quantitative framework for the study of neurodevelopmental disorders and degenerative diseases.

Systems biology for single cell RNA-Seq data
Speaker: Dr Tom Thorne
Date: Thursday 10 December 2020
Abstract: Single cell RNA-Seq data is challenging to analyse due to problems like dropout and cell type identification. We present a novel clustering approach that applies mixture models to learn interpretable clusters from RNA-Seq data, and demonstrate how it can be applied to publicly available scRNA-Seq data. Having inferred groupings of the cells, we can then also attempt to learn networks from the data. These approaches are widely applicable to single cell RNA-Seq datasets where there is a need to identify and characterise sub-populations of cells.

Genetic control of BMI dynamics: a tale of longitudinal growth models and instrumental variables
Speaker: Dr. Alex Couto Alves
Date: Thursday 27 February 2020
Abstract: Critical periods in body mass index (BMI) trajectory predict childhood obesity and cardio-metabolic conditions. BMI trajectory is nonlinear and nonmonotonic reflecting the influence of genetics, pre-conceptional, gestational, and chilldhood environment. However, the regulation of BMI dynamics in childhood is poorly understood.

Here, we discuss the application of growth models to longitudinal BMI data, which we then use to identify genes controlling BMI dynamics. We estimate model parameters reflecting age and BMI at different critical periods in infancy and childhood and demonstrate that different genetic factors control BMI in these periods.

In the second part of this talk, I will present preliminary results delineating a mechanism linking birth weight to BMI dynamics using an instrumental variable approach. We show that childhood BMI partly mediates the influence of birth weight on adult BMI. However, this study also reveals that alternative pathways must exist, suggesting that prevention of childhood obesity may need to start earlier than originally thought.

This work informs on the targets and periods for prevention and treatment of childhood obesity and adult cardiometabolic conditions

New developments in global sensitivity analysis of engineering models
Speaker: Oleksiy Klymenko
Date: Thursday 28 November 2019
Abstract: Mathematical modelling plays crucial role in the design and operation of man-made systems ranging from small appliances to industrial manufacturing and distribution facilities and further to overarching approaches such as Life Cycle Analysis. Many ensuing models encompass numerous physical, chemical, biological, economic, etc. phenomena in multi-scale settings and involve making optimal decisions regarding system configuration and its optimal model-predictive control.

However, optimal design and operation of such process systems is subject to multiple sources of uncertainty, the effect of which on model outputs (e.g., Key Performance Indicators (KPIs) of a process or Critical Quality Attributes (CQAs) of a product) must be quantified in order to ensure robust system design and operational performance.

In this talk I will give an overview of Global Sensitivity Analysis (GSA) – a tool for model analysis under uncertainty, its applications in engineering and new computational approaches for models involving inequality constraints.

The role of noise in quantum decoherence in cellular systems
Speaker: Lester Buxton
Date: Thursday 10 October 2019
Abstract: Quantum mechanics has been applied to many areas of physics ranging from semiconductors, to computing, to cryptography. In recent years the study of quantum biology has gained momentum, highlighting the fundamental problem of explaining how biological systems may remain coherent in warm and wet cellular environments.

Making use of the Caldeira-Leggett model for open quantum systems, where the quantum system of interest is linearly coupled to a bath of harmonics oscillators, we study the effect of environmental noise on quantum decoherence. Adapting the Caldeira-Leggett model for this noisy system requires first the introduction of the Caldirola-Kanai Hamiltonian into the influence functional, in order to mimic environmental induced damping terms in the oscillators' equations of motion. This will be followed by including appropriate noise terms in the CK Hamiltonian.

The general aim of this project is to see if this model can extend decoherence times of quantum systems.

The effect of spectral density on decoherence dynamics of open quantum systems
Speaker: Sapphire Lally
Date: Thursday 10 October 2019
Abstract: The Caldeira-Leggett model is a successful way of describing the reduced dynamics of a multi-level quantum system in constant interaction with a reservoir of harmonic oscillators.

In open quantum systems, the spectral density describes the distribution of reservoir frequency modes. The Caldeira-Leggett model assumes a spectral density which is Ohmic and Markovian. Initial experimental results suggest that a reservoir of harmonic oscillators has a strongly sub-Ohmic, non-Markovian spectral density.

Here, the Caldeira-Leggett model is extended to an Ohmic non-Markovian spectral density, with the prospect of generalising to non-Ohmic spectral densities. This extended model should be applicable to a wide range of systems and may predict increased decoherence times of the quantum system.

Speaker: Onur Oktay (University of Surrey)
Date: 2 May 2023
Title: Binary-coupling sparse SYK model: Spectral statistics and chaotic dynamics

Speaker: Suvajit Majumder (City University London)
Date: 25 April 2023
Title: The R-mAtrIx Net

Speaker: Leander Wyss (University of Surrey)
Date: 14 March 2023
Title: Strings and Spins in Deformed AdS/CFT

Speaker: Roberto D'Onofrio (University of Surrey)
Date: Monday 27 February 2023
Title: Monge-Ampere Geometry and Geophysical Fluid Dynamics

Speaker: Daniele Bielli (University of Surrey)
Date: Tuesday 21 February 2023
Title: Non-abelian T-duality in superspace

Speaker: Benoit Vicedo (University of York)
Date: Tuesday 14 February 2023
Title: 2d integrable field theories from 4d Chern-Simons theory

Speaker: Lewis Napper (University of Surrey)
Date: Monday 6 February 2023
Title: Monge-Ampere Geometry and the Navier-Stokes Equation

Speaker: Edgar Perez Bolanos (King's College London)
Date: Tuesday 6 December 2022
Title: Twisted covariant form hierarchies and hidden symmetries

Speaker: Sergei Ovchinnikov (University of Edinburgh)
Date: Tuesday 29 November 2022
Title: Uniqueness of supersymmetric AdS₅ black holes

Speaker: Arnab Kundu (Saha Institute of Nuclear Physics)
Date: Tuesday 22 November 2022
Title: Synthesis of Dip-Ramp-Plateau, black holes and a semi-classical analysis

Speaker: Ben Hoare (Durham University)
Date: Tuesday 15 November 2022
Title: Integrable deformations of Z₂ and Z₄ permutation cosets

Speaker: Fabrizio Nieri (Trinity College Dublin)
Date: Tuesday 8 November 2022
Title: Spectral Duality in 2d CFT: Yangian W Algebras and Dual-AGT Correspondence

Speaker: Daniele Farotti (University of Surrey)
Date: Tuesday 1 November 2022
Title: Heterotic de-Sitter solutions

Conferences

Date: Tuesday 28 April 2022
Title: 16th meeting of the South East Mathematical Physics Seminars (SEMPS)

Date: 11 - 13 April 2022
Title: YOUNGST@RS - Rebuilding the tower of Babel: bringing together the various languages of color-kinematics duality

Seminars

Speaker: Roberto Ruíz (Complutense University of Madrid)
Date: Tuesday 21 June 2022
Title: Bosonic strings on AdS₃×S³ with Neveu-Schwarz-Neveu-Schwarz flux

Speaker: Vaibhav Gautam (University of Surrey)
Date: Tuesday 7 June 2022
Title: Matrix Entanglement

Speaker: Juan Miguel Nieto Garcia (University of Surrey)
Date: Tuesday 24 May 2022
Title: Jordan blocks and the Bethe ansatz: the eclectic spin chain as a limit

Speaker: Damián Galante (King's College London)
Date: Tuesday 10 May 2022
Title: De Sitter horizons and holography

Speaker: Daniele Farotti (University of Surrey)
Date: Tuesday 26 April 2022
Title: Supersymmetric de Sitter solutions in D=11 supergravity

Speaker: Davide Cassani (University of Padua)
Date: Tuesday 29 March 2022
Title: Towards the quantum entropy of BPS AdS₅ black holes

Speaker: Raghav Govind Jha (Perimeter Institute)
Date: Tuesday 22 February 2022
Title: Large N matrix models using Monte Carlo and Bootstrap

Speaker: Paul Ryan (King's College, London)
Date: Tuesday 8 February 2022
Title: Separation of variables and correlation functions in high-rank integrable systems

Speaker: Daniele Bielli (University of Surrey)
Date: Tuesday 11 January 2022
Title: Super non-abelian T-duality of principal chiral and coset models

Speaker: Brandon Robinson (KU Leuven)
Date: Tuesday 7 December 2021
Title: Weyl anomalies for conformal defects

Speaker: Daniele Farotti (University of Surrey)
Date: Tuesday 16 November 2021
Title: Supersymmetry Enhancement of Heterotic Horizons

Speaker: Jack Holden (University of Southampton)
Date: Tuesday 2 November 2021
Title: Global symmetries and partial confinement

Speaker: Julius Julius (King's College, London)
Date: Tuesday 12 October 2021
Title: Bootstrability for 1d defect CFT

Speaker: Vladimir Rubtsov (University of Angers)
Date: Tuesday 5 October 2021
Title: Quantization of Monodromy data for confluent Painlevé systems, Calabi-Yau 3-algebras and degenerated non-commutative del Pezzo surfaces

Conferences

Date: 17 - 20 August 2021
Title: Integrability in lower-dimensional AdS/CFT

Seminars

Speaker: Lorenzo Raspollini (University of Surrey)
Date: Tuesday 27 July 2021
Title: Higher gauge theory, BV formalism and self-dual theories from twistor space

Speaker: Tommaso Macrelli (University of Surrey)
Date: Tuesday 20 July 2021
Title: Homotopy algebras, gauge theories and gravity

Speaker: Paul Heslop (Durham University)
Date: Tuesday 11 May 2021
Title: Towards the Virasoro—Shapiro Amplitude in AdS₅ × S⁵

Speaker: Chethan Krishnan (Indian Institute of Science)
Date: Tuesday 20 April 2021
Title: Hints of gravitational ergodicity

Speaker: Xizhi Han (Stanford University)
Date: Tuesday 16 March 2021
Title: Neural quantum state in matrix quantum mechanics

Speaker: Marcos Crichigno (Imperial College, London)
Date: Tuesday 26 January 2021
Title: Supersymmetry and quantum computation 

Speaker: James Drummond (University of Southampton)
Date: Tuesday 17 November 2020
Title: Amplitudes, tropical geometry, and cluster algebras

Speaker: Andrea Fontanella (Humboldt University of Berlin)
Date: Tuesday 13 October 2020
Title: Classical integrability in Lie algebra expanded coset sigma models

Speaker: Severin Bunk (University of Hamburg)
Date: Tuesday 22 September 2020
Title: Symmetries of gerbes and applications in geometry and physics

Speaker: Tommaso Macrelli (University of Surrey)
Date: Tuesday 1 September 2020
Title: BV formalism, QFT, and gravity: a homotopy perspective