A facile approach for generating ordered oxygen vacancies in metal oxides
Nature Materials, Published online: 07 March 2025; doi:10.1038/s41563-025-02171-4
A simple method combining thermal activation and electric fields is demonstrated to efficiently generate ordered vacancies in bulk metal oxides, which can be used for broad applications.Vapour–liquid–solid–solid growth of two-dimensional non-layered β-Bi<sub>2</sub>O<sub>3</sub> crystals with high hole mobility
Nature Materials, Published online: 07 March 2025; doi:10.1038/s41563-025-02141-w
High-quality, non-layered 2D β-Bi2O3 crystals are grown using a vapour–liquid–solid–solid growth technique. These crystals demonstrate promising properties for p-channel field-effect transistors.Stiff and self-healing hydrogels by polymer entanglements in co-planar nanoconfinement
Nature Materials, Published online: 07 March 2025; doi:10.1038/s41563-025-02146-5
Mechanical stiffness and self-healing properties are difficult to combine in synthetic hydrogels. Using polymer entanglements in co-planar nanoconfinement, stiff and self-healing hydrogels are fabricated, with applications in biology and engineering.Tue 18 Mar 18:00: Beyond the Standard Model of particle physics: a maths-driven journey to the unknown
Our current understanding of the elementary building blocks of Nature, encapsulated by the Standard Model (SM) of particle physics, is one of the most successful theory constructions of the past century, yet it is necessarily incomplete. Several experimental observations, such as the presence of Dark Matter and the matter-antimatter asymmetry of the Universe, are currently unexplained by the model. In my talk I will discuss how the uncharted territory beyond the Standard Model can be explored and how Maths can be a precious compass to guide us in the fascinating quest for the unknown.
This talk will be free for all, including non-members.
- Speaker: Prof Maria Ubiali
- Tuesday 18 March 2025, 18:00-19:30
- Venue: Pfizer Lecture Theatre, Department of Chemistry, Lensfield Road.
- Series: SciSoc – Cambridge University Scientific Society; organiser: Zhang Xianghao Jeffrey.
Tue 11 Mar 18:00: Black Holes & spin-offs
The popular notion of a black hole “sucking in everything” from its surroundings only happens very close to a black hole. Far away, the pull of the black hole is identical to that of anything else of the same mass. However, black holes do give rise to many remarkable phenomena such as extragalactic quasars and, in our own Galaxy, microquasars. This is because gravity is not the only law of physics that must be obeyed. Matter can be spun off from near black holes in the form of winds and jets that spread through their surroundings and thus cause black holes to have tremendous cosmic influence many light years beyond their event horizons. I will describe various approaches that I employ to investigate these phenomena, and their spin-offs.
This talk will be free for all, including non-members.
- Speaker: Prof Katherine Blundell
- Tuesday 11 March 2025, 18:00-19:30
- Venue: Pfizer Lecture Theatre, Department of Chemistry, Lensfield Road.
- Series: SciSoc – Cambridge University Scientific Society; organiser: Zhang Xianghao Jeffrey.
Wed 12 Mar 16:30: Local structure of finite groups and fusion systems
Local finite group theory has been an important topic, particularly via the Classification of Finite Simple Groups. Fusion systems have helped simplify and extend much of the theory in the last 20 years and are starting to link group theory, representation theory, and algebraic topology. I will give an overview of some key ideas, introduce some examples, and discuss some of my results in the areas.
- Speaker: Baoyu Zhang, University of Birmingham
- Wednesday 12 March 2025, 16:30-17:30
- Venue: MR12.
- Series: Algebra and Representation Theory Seminar; organiser: Adam Jones.
Mon 17 Mar 13:05: Helsing: Simulating a System of Systems
At Helsing, speed and correctness are key in delivering high quality products. The two are often in antithesis; it is difficult to quickly iterate over designs while keeping your codebase correct and vice versa. To build confidence in the systems we build, we use deterministic simulation concepts to enable full end-to-end testing and verification of our software through our in-house simulation platform called Prophecy. Prophecy aims to make simulating easy by providing libraries and services necessary to orchestrate simulations and build a system of systems. This allows other teams to test scenarios up-front and ensure their code and models are resilient to failure, and to run complex, distributed workflows through closed or open loop simulations. In this talk, we’ll be having a look at what deterministic simulation is in a nutshell, how Prophecy works, and how to simulate concurrent code in Rust using tokio.
Please register at the following link: https://forms.office.com/e/E2nCWEpkA9
Please note that it is not a requirement to sign up in order to attend the event
Some catering will be provided
- Speaker: Matei David
- Monday 17 March 2025, 13:05-13:55
- Venue: FW26, William Gates Building.
- Series: Technical Talks - Department of Computer Science and Technology ; organiser: Ben Karniely.
Fri 07 Mar 12:00: Typological Diversity in NLP: What, Why and a Way Forward
To justify the generalisability of multilingual NLP research, multilingual language technology is frequently evaluated on ‘typologically diverse’ language selections. Yet, what this means often remains vague. In this talk, I first discuss what typological diversity means in NLP , and why it matters. Then, I introduce a framework for systematic language sampling, which is inspired by typological insights. Ultimately, the aim of this talk is to inspire research on linguistic typology in NLP that goes beyond merely leveraging databases, but rather incorporates research methodologies from linguistic typology.
- Speaker: Esther Ploeger (Aalborg University)
- Friday 07 March 2025, 12:00-13:00
- Venue: Zoom link: https://cam-ac-uk.zoom.us/j/4751389294?pwd=Z2ZOSDk0eG1wZldVWG1GVVhrTzFIZz09.
- Series: NLIP Seminar Series; organiser: Suchir Salhan.
Tue 13 May 16:00: TBA
Abstract not available
- Speaker: Bernardo Araneda (Edinburgh)
- Tuesday 13 May 2025, 16:00-17:00
- Venue: CMS, MR11.
- Series: Mathematical Physics Seminar; organiser: Professor Maciej Dunajski.
Tue 06 May 16:00: General solution to gauged U(1) anomaly equations
Abstract not available
- Speaker: Ben Allanach (DAMTP)
- Tuesday 06 May 2025, 16:00-17:00
- Venue: CMS, MR11.
- Series: Mathematical Physics Seminar; organiser: Professor Maciej Dunajski.
Mon 17 Mar 16:00: Two New Developments concerning Noether's Two Theorems
In her fundamental 1918 paper, written whilst at Göttingen at the invitation of Klein and Hilbert to help them resolve an apparent paradox concerning the conservation of energy in general relativity, Emmy Noether proved two fundamental theorems relating symmetries and conservation laws of variational problems. Her First Theorem, as originally formulated, relates strictly invariant variational problems and conservation laws of their Euler—Lagrange equations. The Noether correspondence was extended by her student Bessel-Hagen to divergence invariant variational problems. A key issue is when is a divergence invariant variational problem equivalent to a strictly invariant one. Here, I illustrate these issues using a very basic example from her original paper, and then highlight the role of Lie algebra cohomology in resolving this question in general. This part includes some provocative remarks on the role of invariant variational problems in the modern formulation of fundamental physics.
Noether’s Second Theorem concerns variational problems admitting an infinite-dimensional symmetry group depending on an arbitrary function. I first recall the two well-known classes of partial differential equations that admit infinite hierarchies of higher order generalized symmetries: 1) linear and linearizable systems that admit a nontrivial point symmetry group; 2) integrable nonlinear equations such as Korteweg—de Vries, nonlinear Schrödinger, and Burgers’. I will then introduce a new general class: 3) underdetermined systems of partial differential equations that admit an infinite-dimensional symmetry algebra depending on one or more arbitrary functions of the independent variables. An important subclass of the latter are the underdetermined Euler—Lagrange equations arising from a variational principle that admits an infinite-dimensional variational symmetry algebra depending on one or more arbitrary functions of the independent variables. According to Noether’s Second Theorem, the associated Euler—Lagrange equations satisfy Noether dependencies and are hence underdetermined and the conservation laws corresponding to such symmetries are trivial; examples include general relativity, electromagnetism, and parameter-independent variational principles.
- Speaker: Peter Olver
- Monday 17 March 2025, 16:00-17:00
- Venue: Centre for Mathematical Sciences, MR13.
- Series: Applied and Computational Analysis; organiser: Matthew Colbrook.
Mon 10 Mar 14:00: An Onsager theorem in 2D
I will discuss the Nash iterative construction of non-conservative weak solutions to the Euler equations, with a particular focus on the difficulties presented by the two-dimensional case. I will then present a linear decoupling method, which enabled the construction of examples achieving sharp regularity for the 2D Euler equations, as well as for other systems.
- Speaker: Razvan Radu (Princeton)
- Monday 10 March 2025, 14:00-15:00
- Venue: MR13.
- Series: Partial Differential Equations seminar; organiser: Amelie Justine Loher.
Industrially viable formate production with 50% lower CO2 emissions
DOI: 10.1039/D5EE00452G, Paper Open Access   This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence.Fanxu Meng, Zihan Shen, Xinlong Lin, Pengfei Song, Tianze Wu, Shibo Xi, Chao Wu, Zhenhui Ma, Daniel Mandler, Zhichuan J. Xu
The conventional production of formic acid is energy-intensive, requiring methanol and carbon monoxide reactions followed by hydrolysis under high temperature and pressure. Methanol electrochemical refinery (e-refinery) offers a sustainable alternative...
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Fri 07 Mar 08:45: Grand Rounds - QICG Canceled
Abstract not available
Canceled
- Speaker: Alison Hayes, Department of Veterinary Medicine
- Friday 07 March 2025, 08:45-10:00
- Venue: LT2.
- Series: Friday Morning Seminars, Dept of Veterinary Medicine; organiser: Fiona Roby.
Thu 13 Mar 15:00: An introduction to quantum graphs and their spectral geometry, with some open questions
Quantum graphs are (usually self-adjoint) second-order differential operators over collections of intervals that are glued at their endpoints (“metric graphs”). We survey recent and past advances in quantum graph eigenvalue estimates, focusing on how geometry, topology, and diffusion-transport phenomena interact. Specifically, we examine surgery techniques—localized graph modifications—to manipulate eigenvalues. We also explore transport and transport-diffusion equations on directed graphs, highlighting how directional flow and non-symmetric operators impact spectral properties. We discuss adapting surgery techniques to control these effects, emphasizing the link between edge transmission/boundary conditions, diffusion-transport dynamics, and resulting eigenvalues.
- Speaker: Delio Mugnolo
- Thursday 13 March 2025, 15:00-16:00
- Venue: Centre for Mathematical Sciences, MR14.
- Series: Applied and Computational Analysis; organiser: Matthew Colbrook.
Fri 21 Mar 14:00: Number of quantifiers in 3-variable logic on linear orders
Grohe and Schweikardt proved in 2005 that the smallest sentence of 3-variable logic FO3 that can separate a linear order of length n from all shorter linear orders is of length at least O(√n). The best upper bound for the length of such a sentence that we found in the literature is O(n).
In this talk I present a new game that characterizes definability by sentences of FOk with n quantifiers. Using this game I show that there is a sentence of FO3 with 2m+1 quantifiers that is true in a linear order if and only if its length is at least 2m(m+1)+1. Furthermore, I show a matching lower bound result using the game: all linear orders of length at least 2m(m+1)+1 are equivalent with respect to all sentences of FO3 with at most 2m+1 quantifiers. The first of these results implies O(√n) upper bound for the length of a sentence of FO3 needed for separating linear orders of length n from shorter linear orders.
(joint work with Kerkko Luosto)
- Speaker: Lauri Hella (Univeristy of Tampere)
- Friday 21 March 2025, 14:00-15:00
- Venue: SS03, Computer Laboratory.
- Series: Logic and Semantics Seminar (Computer Laboratory); organiser: Anuj Dawar.
Thu 06 Mar 17:00: On Vanishing Gradients, Over-Smoothing, and Over-Squashing in GNNs: Bridging Recurrent and Graph Learning hybrid : meet.google.com/bhz-scdk-unp
Graph Neural Networks (GNNs) are models that leverage the graph structure to transmit information between nodes, typically through the message-passing operation. While widely successful, this approach is well known to suffer from the over-smoothing and over-squashing phenomena, which result in representational collapse as the number of layers increases and insensitivity to the information contained at distant and poorly connected nodes, respectively. In this paper, we present a unified view of these problems through the lens of vanishing gradients, using ideas from linear control theory for our analysis. We propose an interpretation of GNNs as recurrent models and empirically demonstrate that a simple state-space formulation of a GNN effectively alleviates over-smoothing and over-squashing at no extra trainable parameter cost. Further, we show theoretically and empirically that (i) GNNs are by design prone to extreme gradient vanishing even after a few layers; (ii) Over-smoothing is directly related to the mechanism causing vanishing gradients; (iii) Over-squashing is most easily alleviated by a combination of graph rewiring and vanishing gradient mitigation. We believe our work will help bridge the gap between the recurrent and graph neural network literature and will unlock the design of new deep and performant GNNs
also: meet.google.com/bhz-scdk-unp
hybrid : meet.google.com/bhz-scdk-unp
- Speaker: Alvaro Arroyo, University of Oxford
- Thursday 06 March 2025, 17:00-17:45
- Venue: Lecture Theatre 1, Computer Laboratory, William Gates Building.
- Series: Foundation AI; organiser: Pietro Lio.
Thu 06 Mar 11:00: 2025 Scott Lectures - Quantum science with atom-like systems in diamond
Abstract not available
- Speaker: Professor Mikhail Lukin, Harvard University
- Thursday 06 March 2025, 11:00-12:00
- Venue: Lecture Theatre, Level 1, Ray Dolby Centre, Cavendish Laboratory, JJ Thomson Avenue, CB3 0US.
- Series: Scott Lectures; organiser: Leona Hope-Coles.
Fri 21 Mar 14:00: Number of quantifiers in 3-variable logic on linear orders
Grohe and Schweikardt proved in 2005 that the smallest sentence of 3-variable logic FO3 that can separate a linear order of length n from all shorter linear orders is of length at least O(√n). The best upper bound for the length of such a sentence that we found in the literature is O(n).
In this talk I present a new game that characterizes definability by sentences of FOk with n quantifiers. Using this game I show that there is a sentence of FO3 with 2m+1 quantifiers that is true in a linear order if and only if its length is at least 2m(m+1)+1. Furthermore, I show a matching lower bound result using the game: all linear orders of length at least 2m(m+1)+1 are equivalent with respect to all sentences of FO3 with at most 2m+1 quantifiers. The first of these results implies O(√n) upper bound for the length of a sentence of FO^3 needed for separating linear orders of length n from shorter linear orders.
(joint work with Kerkko Luosto)
- Speaker: Lauri Hella (Univeristy of Tampere)
- Friday 21 March 2025, 14:00-15:00
- Venue: SS03, Computer Laboratory.
- Series: Logic and Semantics Seminar (Computer Laboratory); organiser: Anuj Dawar.
Thu 06 Mar 11:00: 2025 Scott Lectures - Quantum science with atom-like systems in diamond
Abstract not available
- Speaker: Professor Mikhail Lukin, Harvard University
- Thursday 06 March 2025, 11:00-12:00
- Venue: Lecture Theatre, Ray Dolby Centre, Cavendish Laboratory, JJ Thomson Avenue, CB3 0US.
- Series: Scott Lectures; organiser: Leona Hope-Coles.