Wed 14 May 15:05: Type-driven Development with Idris 2
Idris is a functional programming language with first-class types, which allow properties to be expressed in the type system, and with an interactive type-driven editor which allows programs to be developed as a formal conversation with the machine. In this talk I will introduce Idris and its type system, and cover recent developments in Idris 2. In particular, I will describe how the quantities in the type system give additional expressivity which allows us to implement state machines and communicating systems and verify their properties, interactively.
Link to join virtually: https://cam-ac-uk.zoom.us/j/87421957265
This talk is being recorded. If you do not wish to be seen in the recording, please avoid sitting in the front three rows of seats in the lecture theatre. Any questions asked will also be included in the recording. The recording will be made available on the Department’s webpage
- Speaker: Dr Edwin Brady - School of Computer Science, University of St Andrews
- Wednesday 14 May 2025, 15:05-15:55
- Venue: Lecture Theatre 1, Computer Laboratory, William Gates Building.
- Series: Wednesday Seminars - Department of Computer Science and Technology ; organiser: Ben Karniely.
Thu 05 Jun 15:00: Translation Validation for LLVM's AArch64 Backend
Alive2 is a practical oracle for determining whether a transformation on LLVM IR is a refinement—that is, whether it is valid under the rules for LLVM optimizations. In this talk I’ll describe an analogous translation validation solution for LLVM ’s AArch64 backend that we’ve used to find 42 miscompilation bugs, many of which were in architecture-neutral code and hence could have also affected other backends. Our tool, arm-tv, reuses Alive2 as a source of LLVM semantics and offers a choice of two AArch64 semantics, one that we wrote by hand and the other derived from ARM ’s machine readable specification of their ISA .
John Regehr is a computer science professor at the University of Utah, USA . He liked to build tools for compiler developers to use, and then write papers about them.
- Speaker: John Regehr - University of Utah
- Thursday 05 June 2025, 15:00-16:00
- Venue: Computer Laboratory, William Gates Building, LT1.
- Series: compiler socials; organiser: Luisa Cicolini.
Thu 15 May 11:30: Vertical mixing and associated biogeochemical fluxes via radium isotopes
Abstract not available
- Speaker: Tristan McKenzie, Uni of Gothenberg
- Thursday 15 May 2025, 11:30-12:30
- Venue: Open Plan Area, Institute for Energy and Environmental Flows, Madingley Rise CB3 0EZ.
- Series: Institute for Energy and Environmental Flows (IEEF); organiser: Catherine Pearson.
Monitoring α/β Particles Using a Copper Cluster Scintillator Detector
A copper cluster scintillator with excellent stability and scintillation performance, which shows high sensitivity response to α/β particles, is constructed. By coupling it with PMT and nuclear electronics system, a surface contamination monitor for precise detection of α/β particles is successfully fabricated.
Abstract
High-energy radiation is widely used in medicine, industry, and scientific research. Meanwhile, the detection of environmental ionizing radiation is essential to ensure the safe use of high-energy radiation. Among radiation detectors, scintillator detectors offer multiple advantages, including simple structure, high sensitivity, excellent environmental adaptability, and a favorable performance-to-price ratio. However, the development of high-performance scintillators that can provide highly sensitive responses to environmental radiation, especially α/β particles, remains a challenge. In this work, a copper cluster (Cu4I4(DPPPy)2 ) with excellent water-oxygen stability is prepared using a simple one-pot method at room temperature. Cu4I4(DPPPy)2 not only exhibits excellent X-ray excited luminescence (XEL) under X-ray irradiation but also demonstrates a highly sensitive scintillation response to α/β particles. By integrating Cu4I4(DPPPy)2 with a photomultiplier tube (PMT) and nuclear electronics, an α/β surface contamination monitor is successfully developed. This monitor enables the sensitive detection of excessive α/β particles in real-world environments. The detection frequency and signal intensity of Cu4I4(DPPPy)2 significantly surpass those of commercial scintillator of YAP:Ce, BGO, PbWO4, and anthracene under identical conditions, highlighting the promising application of metal clusters in low-dose environmental radiation detection.
Wed 28 May 11:00: Conditional Expectation and Machine Learning
The problem addressed by machine learning can also be formulated as one of computing conditional expectation, an approach little explored because of the success of machine learning. The focus of this presentation is to view conditional expectation, not as an alternative, but as a means of performance enhancement for machine learning. In particular, we show that conventional machine learning is itself a vehicle for computing conditional expectation, both post training and during training. A neural network architecture that combine conventional machine learning and computing conditional expectation will be presented.
- Speaker: Eugene Wong(UC Berkeley and Clare Hall, Cambridge)
- Wednesday 28 May 2025, 11:00-12:30
- Venue: Cambridge University Engineering Department, CBL Seminar room BE4-38..
- Series: Machine Learning Reading Group @ CUED; organiser: Xianda Sun.
Wed 28 May 11:00: Conditional Expectation and Machine Learning
The problem addressed by machine learning can also be formulated as one of computing conditional expectation, an approach little explored because of the success of machine learning. The focus of this presentation is to view conditional expectation, not as an alternative, but as a means of performance enhancement for machine learning. In particular, we show that conventional machine learning is itself a vehicle for computing conditional expectation, both post training and during training. A neural network architecture that combine conventional machine learning and computing conditional expectation will be presented.
- Speaker: Eugene Wong(UC Berkeley and Clare Hall, Cambridge)
- Wednesday 28 May 2025, 11:00-12:30
- Venue: Cambridge University Engineering Department, CBL Seminar room BE4-38..
- Series: Machine Learning Reading Group @ CUED; organiser: Xianda Sun.
Mechanical Resonant Sensing of Spin Texture Dynamics in a 2D Antiferromagnet
Detection of antiferromagnetic spin texture in a 2D magnetic crystal is achieved through nanomechanical resonators at radio frequencies. Sharp magnetic transitions that lead to abrupt changes in mechanical linear and nonlinear responses are assigned to antiferromagnetic domain motions. The results indicate rich and fluid-like dynamics between the coupled spin and lattice at the transition field.
Abstract
The coupling between the spin degrees of freedom and macroscopic mechanical motions, including striction, shearing, and rotation, has attracted wide interest with applications in actuation, transduction, and information processing. Experiments so far have established the mechanical responses to the long-range ordered or isolated single spin states. However, it remains elusive whether mechanical motions can couple to a different type of magnetic structure, the non-collinear spin textures, which exhibit nanoscale spatial variations of spin (domain walls, skyrmions, etc.) and are promising candidates to realize high-speed computing devices. Here, collective spin texture dynamics is detected with nanoelectromechanical resonators fabricated from 2D antiferromagnetic (AFM) MnPS3 with 10−9 strain sensitivity. By examining radio frequency mechanical oscillations under magnetic fields, new magnetic transitions are identified with sharp dips in resonant frequency. They are attributed to collective AFM domain wall motions as supported by the analytical modeling of magnetostriction and large-scale spin-dynamics simulations. Additionally, an abnormally large modulation in the mechanical nonlinearity at the transition field infers a fluid-like response due to ultrafast domain motion. The work establishes a strong coupling between spin texture and mechanical dynamics, laying the foundation for electromechanical manipulation of spin texture and developing quantum hybrid devices.
Decoupling Lithium Reutilization Behavior under Different Discharge Rates for Anode‐Free Lithium Metal Batteries
This work uncovers the Li0 reutilization behavior of AFLMBs at different discharge rates, which exhibits a “volcano-type” variation. The opposite effects of the distribution relationship between fresh Li and residue Li0 and concentration polarization at specific discharge rate dominate Li0 reutilization. This cognition provides guidance toward high-power density AFLMBs under practical conditions.
Abstract
Anode-free lithium metal battery (AFLMB) has become an excellent candidate for long endurance electric vehicles and electric low altitude aircraft, profiting from its high energy density as well as outstanding manufacturing safety. However, the limitation at high discharge rates of AFLMBs is shrouded in mystery, yet to achieve more attention. Herein, the limitation of fast discharge for AFLMBs is dissected exhaustively, and a symptomatic strategy to break the limit is put forward, in order to eliminate the inevitable mismatch that lies in the inferior performance of AFLMBs. A “volcano-type” curve of capacity retention of AFLMBs is discovered with the discharge rate increased. Systematic investigation revealed that the overlapped spatial relationship between fresh deposited Li and residue Li0 facilitated the utilization of “recoverable Li0” (Li0) at the prophase of discharge rate increase. However, further enhanced discharge rate induced large concentration polarization (η conc), reflecting limited Li+ diffusion. Enabling the electrolyte to rapidly transport Li+ by lowering η conc increased the optimal discharge rate as well as the cycling stability of AFLMBs. This work reveals the rate-determining step for high-rate discharge and expands the employment boundary of AFLMBs under harsh conditions, providing a significant complement of present knowledge with respect to the power performance of AFLMBs.
Concurrent energy storage and decarbonization by metal-CO2 batteries: aqueous or non-aqueous?
DOI: 10.1039/D5EE00266D, Review ArticleZaiping Guo, Divyani Gupta, Jinshuo Zou, Jianfeng Mao
Rechargeable metal-CO2 batteries (RMCBs) are highly promising for renewable energy storage and simultaneous reduction of carbon footprint from the environment, making it very attractive for next-generation battery development. An electrolyte...
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Achromatic metagratings for compact near-eye displays
Nature Nanotechnology, Published online: 30 April 2025; doi:10.1038/s41565-025-01896-2
An achromatic metagrating waveguide with a tailored periodic structure designed using a stochastic topology optimization algorithm efficiently guides red, green and blue light at the same angle. This structure provides a compact, lightweight architecture for waveguide-based full-colour augmented reality displays.Single-layer waveguide displays using achromatic metagratings for full-colour augmented reality
Nature Nanotechnology, Published online: 30 April 2025; doi:10.1038/s41565-025-01887-3
A 500-μm-thick design simplifies fabrication and reduces weight while offering good brightness and colour uniformity for augmented reality near-eye optical design.Aromatic amines boost electrolysis
Nature Energy, Published online: 30 April 2025; doi:10.1038/s41560-025-01765-1
The slow kinetics of hydrogen evolution in alkaline solutions limit the current density of alkaline electrolysers. Research now demonstrates that the addition of aromatic amines to the electrolyte enhances alkaline hydrogen evolution, a strategy that is readily applicable to existing electrolysers.Fri 16 May 16:00: Can AI weather and climate emulators predict out-of-distribution gray swan extreme events?
Artificial intelligence (AI) is transforming weather and climate modeling. For example, neural network-based weather models can now outperform physics-based models for up to 15-day forecasts at a fraction of the computing time. However, these AI models have challenges with learning the rarest yet most impactful weather extremes, particularly the gray swans (i.e., physically possible events so rare they have never been seen in the training set). They also poorly learn multi-scale chaotic dynamics. I will discuss some of these challenges, as well as some of the surprising capabilities of these models, e.g., transferring what they learn from one region to another for dynamically similar event. I will present ideas around integrating tools from applied math, climate physics, and AI to address some of these challenges and make progress. In particular, I will discuss the use if rare event sampling algorithms and the Fourier transform and adjoint of the deep neural networks.
- Speaker: Prof Pedram Hassanzedeh, University of Chicago
- Friday 16 May 2025, 16:00-17:00
- Venue: MR2.
- Series: Fluid Mechanics (DAMTP); organiser: Professor Grae Worster.
Tue 13 May 16:00: Einstein-Maxwell instantons, complex structures, and the Geroch group
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.
Wed 07 May 13:00: The SIREN study at five years: Tracking SARS-CoV-2 and respiratory infections in UK healthcare workers since 2020
All are invited to the Bradford Hill Seminar:
The SIREN study at five years: Tracking SARS -CoV-2 and respiratory infections in UK healthcare workers since 2020
Speaker: Victoria Hall, Consultant Epidemiologist, Antimicrobial Resistance & Healthcare Associated Infections Division of the UK Health Security Agency (UK HSA )
Register to attend Please note this will be a free hybrid seminar, with the option to attend in-person (Large Seminar Room, East Forvie Building, Forvie Site, Robinson Way, Cambridge CB2 0SR ) or virtually (via Zoom).
No registration is required to attend in person.
Register in advance to attend this seminar online at:
https://cam-ac-uk.zoom.us/meeting/register/CoavXVmNQtWN8j8TOFv-rg#/registration
Abstract The SARS -CoV-2 Immunity and Reinfection Evaluation (SIREN) study is a prospective cohort study of hospital-based healthcare workers across the UK. It was established in 2020 as a pandemic response study, with over 44,000 healthcare workers recruited from 135 NHS trusts/health boards. The study initially investigated SARS -CoV-2 reinfections and the durability of immunity following infection, and subsequently COVID -19 vaccination. It has expanded its scope to evaluate Winter Pressures on the healthcare workforce, and questions related to immunity more broadly.
SIREN has been running since 2024. This has involved collecting data on symptoms and absence from time off work trends in around 5000 participants recruited from the original SIREN cohort. In addition to investigating Winter Pressures, SIREN provides an opportunity to address new research questions of public health importance that impact healthcare workers, including the emergence of multidrug resistant organisms and risk factors for healthcare associated infections.
More details on the study and publications from the study can be found here: https://www.gov.uk/guidance/siren-study
About Victoria Hall Victoria Hall is a Consultant Epidemiologist in the Antimicrobial Resistance & Healthcare Associated Infections Division of the UK Health Security Agency and has been leading the SIREN study team since 2020. She completed public health speciality training in the East of England and the UK Field Epidemiology Training Programme based in South East and London Regional Field Epidemiology Service. She holds a part-time position at the Institute for Health Informatics, UCL working on research on infections and AMR in care homes with the VIVALDI study.
About the Bradford Hill seminars The Bradford Hill seminar series is the principal series of The Cambridge Population Health Sciences Partnership, in collaboration with the PHG Foundation. This comprises the Departments of Public Health & Primary Care, MRC Biostatistics Unit and MRC Epidemiology Unit at the University of Cambridge, bringing together a multi-disciplinary partnership of academics and public health professionals. The Bradford Hill seminar programme of internationally recognised speakers covers topics of broad interest to our public health research community. It aims to transcend as well as connect the activities of our individual partners.
All are welcome at our Bradford Hill seminars.
- Speaker: Victoria Hall, UK Health Security Agency
- Wednesday 07 May 2025, 13:00-14:00
- Venue: Large Seminar Room, East Forvie Building, Forvie Site Robinson Way Cambridge CB2 0SR..
- Series: Bradford Hill Seminars; organiser: Paul Browne.
Wed 07 May 13:00: The SIREN study at five years: Tracking SARS-CoV-2 and respiratory infections in UK healthcare workers since 2020
All are invited to the Bradford Hill Seminar:
The SIREN study at five years: Tracking SARS -CoV-2 and respiratory infections in UK healthcare workers since 2020
Speaker: Victoria Hall, Consultant Epidemiologist, Antimicrobial Resistance & Healthcare Associated Infections Division of the UK Health Security Agency (UK HSA )
Register to attend Please note this will be a free hybrid seminar, with the option to attend in-person (Large Seminar Room, East Forvie Building, Forvie Site, Robinson Way, Cambridge CB2 0SR ) or virtually (via Zoom).
No registration is required to attend in person.
Register in advance to attend this seminar online at:
https://cam-ac-uk.zoom.us/meeting/register/CoavXVmNQtWN8j8TOFv-rg#/registration
Abstract The SARS -CoV-2 Immunity and Reinfection Evaluation (SIREN) study is a prospective cohort study of hospital-based healthcare workers across the UK. It was established in 2020 as a pandemic response study, with over 44,000 healthcare workers recruited from 135 NHS trusts/health boards. The study initially investigated SARS -CoV-2 reinfections and the durability of immunity following infection, and subsequently COVID -19 vaccination. It has expanded its scope to evaluate Winter Pressures on the healthcare workforce, and questions related to immunity more broadly.
SIREN has been running since 2024. This has involved collecting data on symptoms and absence from time off work trends in around 5000 participants recruited from the original SIREN cohort. In addition to investigating Winter Pressures, SIREN provides an opportunity to address new research questions of public health importance that impact healthcare workers, including the emergence of multidrug resistant organisms and risk factors for healthcare associated infections.
More details on the study and publications from the study can be found here: https://www.gov.uk/guidance/siren-study
About Victoria Hall Victoria Hall is a Consultant Epidemiologist in the Antimicrobial Resistance & Healthcare Associated Infections Division of the UK Health Security Agency and has been leading the SIREN study team since 2020. She completed public health speciality training in the East of England and the UK Field Epidemiology Training Programme based in South East and London Regional Field Epidemiology Service. She holds a part-time position at the Institute for Health Informatics, UCL working on research on infections and AMR in care homes with the VIVALDI study.
About the Bradford Hill seminars The Bradford Hill seminar series is the principal series of The Cambridge Population Health Sciences Partnership, in collaboration with the PHG Foundation. This comprises the Departments of Public Health & Primary Care, MRC Biostatistics Unit and MRC Epidemiology Unit at the University of Cambridge, bringing together a multi-disciplinary partnership of academics and public health professionals. The Bradford Hill seminar programme of internationally recognised speakers covers topics of broad interest to our public health research community. It aims to transcend as well as connect the activities of our individual partners.
All are welcome at our Bradford Hill seminars.
- Speaker: Victoria Hall, UK Health Security Agency
- Wednesday 07 May 2025, 13:00-14:00
- Venue: Large Seminar Room, East Forvie Building, Forvie Site Robinson Way Cambridge CB2 0SR..
- Series: Bradford Hill Seminars; organiser: Paul Browne.
Fri 06 Jun 15:00: When is Multilinguality a Curse? Language Modeling for 350 Languages
NOTE THE UNUSUAL TIME FOR THIS SEMINAR
Language models work well for a small number of languages. For the other languages, the best existing language model is likely multilingual, still with the vast majority of the training data coming from English and a few “priority” languages. We show that in many cases, multilinguality leads to worse performance across many languages due to limited model capacity. We then train a suite of over 1,000 monolingual models for 350 languages, finding that these models can outperform multilingual models over ten times their size. However, multilinguality can also be a blessing: we train a small number of controlled bilingual models in order to study how crosslingual transfer happens. We aim to better understand transfer learning in order to better leverage multilinguality to improve language model performance for all languages.
- Speaker: Catherine Arnett and Tyler Chang (EleutherAI and UC San Diego)
- Friday 06 June 2025, 15:00-16:00
- Venue: ONLINE ONLY. Here is the Zoom link: https://cam-ac-uk.zoom.us/j/4751389294?pwd=Z2ZOSDk0eG1wZldVWG1GVVhrTzFIZz09.
- Series: NLIP Seminar Series; organiser: Suchir Salhan.
Fri 16 May 16:00: Title to be confirmed
Abstract not available
- Speaker: Prof Pedram Hassanzedeh, University of Chicago
- Friday 16 May 2025, 16:00-17:00
- Venue: MR2.
- Series: Fluid Mechanics (DAMTP); organiser: Professor Grae Worster.
Fri 30 May 16:00: PhD Students' talks
Abstract not available
- Speaker: Speakers listed in abstract in due course
- Friday 30 May 2025, 16:00-17:00
- Venue: MR2.
- Series: Fluid Mechanics (DAMTP); organiser: Professor Grae Worster.
Fri 06 Jun 16:00: Numerical simulations of multiphase flows with various complexities
Abstract not available
- Speaker: Prof Omar Matar, Imperial College London
- Friday 06 June 2025, 16:00-17:00
- Venue: https://cassyni.com/s/fmws.
- Series: Fluid Mechanics (DAMTP); organiser: Professor Grae Worster.