Wed 21 May 14:30: Title to be confirmed
Abstract not available
- Speaker: Samuel Brookes, University of Cambridge
- Wednesday 21 May 2025, 14:30-15:00
- Venue: Unilever Lecture Theatre, Yusuf Hamied Department of Chemistry.
- Series: Theory - Chemistry Research Interest Group; organiser: Lisa Masters.
Tue 04 Mar 14:00: The scaling limit of random planar maps with large faces.
In this talk, we consider large Boltzmann stable planar maps with index (1,2). In recent joint work with Nicolas Curien and Grégory Miermont, we established that this model converges, in the scaling limit, to a random compact metric space that we construct explicitly. The goal of this presentation is to outline the main steps of our proof. We will also discuss various properties of the scaling limit, including its topology and geodesic structure.
- Speaker: Armand Riera (Paris)
- Tuesday 04 March 2025, 14:00-15:00
- Venue: MR12.
- Series: Probability; organiser: ww295.
Tue 18 Feb 14:00: Height gap of the planar Brownian motion
Schramm and Sheffield introduced the notion of height gap for the continuum Gaussian free field (GFF) in dimension 2. It turns out that this height gap has a natural interpretation through clusters of Brownian loops arising in Brownian loop soups representations of the GFF . By considering different intensity parameters 0
- Speaker: Titus Lupu (Paris)
- Tuesday 18 February 2025, 14:00-15:00
- Venue: MR12.
- Series: Probability; organiser: ww295.
Wed 26 Feb 15:30: Freshwater displacement effect on the Weddell Gyre carbon budget
The Weddell Gyre mediates carbon exchange between the abyssal ocean and atmosphere, which is critical to global climate. This region also features large and highly variable freshwater fluxes due to seasonal sea ice, net precipitation, and glacial melt; however, the impact of these freshwater fluxes on the regional carbon cycle has not been fully explored. Using a novel budget analysis of dissolved inorganic carbon (DIC) mass in the Biogeochemical Southern Ocean State Estimate and revisiting hydrographic analysis from the ANDREX cruises, we highlight two freshwater-driven transports. Where freshwater with minimal DIC enters the ocean, it displaces DIC -rich seawater outwards, driving a lateral transport of 75±5 Tg DIC /year. Additionally, sea ice export requires a compensating import of seawater, which carries 48±11 Tg DIC /year into the gyre. Though often overlooked, these freshwater displacement effects are of leading order in the Weddell Gyre carbon budget in the state estimate and in regrouped box-inversion estimates. Implications for evaluating basin-scale carbon transports are considered. [Time permitting, I’ll also share some results on the role of heat addition in driving circulation change and warming patterns in the Indian sector of the Southern Ocean.]
- Speaker: Benjamin Taylor, Scripps Institution of Oceanography
- Wednesday 26 February 2025, 15:30-16:30
- Venue: BAS Seminar Room 1.
- Series: British Antarctic Survey - Polar Oceans seminar series; organiser: Dr Birgit Rogalla.
Tue 25 Feb 11:15: Exoplanet Detection with SPIRIT: Infrared CMOS Photometry and the Discovery of the Hot Neptune TOI-2407b
The SPECULOOS project is dedicated to the discovery of transiting exoplanets around ultracool dwarfs using high-precision ground-based observations. To enhance sensitivity to these cool stars, we have implemented SPIRIT , a new infrared detector utilizing CMOS technology instead of traditional CCDs. In this talk, I will present my work on developing the data pipeline for SPIRIT and optimizing its performance for detecting exoplanet transits. I will also highlight the discovery of TOI -2407b, a Neptune-like planet observed with this system.
- Speaker: Clàudia Janó Muñoz (University of Cambridge)
- Tuesday 25 February 2025, 11:15-12:00
- Venue: Coffee area, Battcock Centre.
- Series: Hills Coffee Talks; organiser: Charles Walker.
Mon 17 Mar 14:00: Title to be confirmed
Abstract not available
- Speaker: Víctor Navarro-Fernández, Imperial College London
- Monday 17 March 2025, 14:00-15:00
- Venue: MR13.
- Series: Partial Differential Equations seminar; organiser: Amelie Justine Loher.
Wed 26 Feb 15:00: From accurate quantum mechanics to converged thermodynamics in solution with machine learning potentials
Obtaining accurate predictions of thermodynamic properties, especially free energies which define the state of a system, is one of the key goals in atomistic simulations. This can enable a direct understanding of atomic-scale processes and provide a direct link to experiment. Achieving this requires converged statistical sampling from accurate wavefunction based potential energy surfaces, which is a formidable challenge due to the very high computational cost of such methods. Here, we leverage advances in machine learning potentials to efficiently obtain converged thermodynamic properties at increasing levels of theory. To showcase the potential of this approach, I will use the ion pairing of CaCO3 as a benchmark system, since it presents a significant challenge from both electronic structure and sampling perspectives. I will show that a machine learning framework based on second order Møller-Plesset Perturbation Theory delivers excellent agreement with experiment for the ion-pair association free energy—a challenging property for first principles atomistic simulations. Furthermore I will show that classical force fields get the right answer for the wrong reasons. Finally, I will discuss steps towards developing CCSD accuracy machine learning models, the ‘gold-standard’ of quantum chemical methods.
- Speaker: Niamh O'Neill, University of Cambridge
- Wednesday 26 February 2025, 15:00-15:30
- Venue: Unilever Lecture Theatre, Yusuf Hamied Department of Chemistry.
- Series: Theory - Chemistry Research Interest Group; organiser: Lisa Masters.
Wed 12 Mar 17:00: Title to be confirmed NOTE UNUSUAL DAY
=== Hybrid talk ===
Join Zoom Meeting https://cam-ac-uk.zoom.us/j/87143365195?pwd=SELTNkOcfVrIE1IppYCsbooOVqenzI.1
Meeting ID: 871 4336 5195
Passcode: 541180
NOTE UNUSUAL DAY
- Speaker: Francisco Ferreira Ruiz (Royal Holloway, University of London)
- Wednesday 12 March 2025, 17:00-18:00
- Venue: MR14 Centre for Mathematical Sciences.
- Series: Formalisation of mathematics with interactive theorem provers ; organiser: Anand Rao Tadipatri.
Thu 13 Feb 17:00: Algebraising foundations of elliptic curves
Elliptic curves are one of the simplest non-trivial objects in algebraic geometry, which are pervasive in modern number theory, but also see applications in point counting algorithms and public key cryptography. Due to their geometric nature, formalising a working definition typically requires a lot of technical machinery, let alone any non-trivial results. Yet, the Lean community has managed to formalise two of the most fundamental theorems in the theory of elliptic curves, with scope for many more projects. In this talk, I will explain these theorems, and how we inadvertently discovered new proofs in our formalisation attempts.
Slides: https://multramate.github.io/talks/afoec/main.pdf
- Speaker: David Angdinata (University College London)
- Thursday 13 February 2025, 17:00-18:00
- Venue: MR14 Centre for Mathematical Sciences.
- Series: Formalisation of mathematics with interactive theorem provers ; organiser: Anand Rao Tadipatri.
Fri 21 Feb 13:00: Free conformally-rescaled hyperboloidal evolution: status and applications
Gravitational wave radiation is only unambiguously defined at future null infinity – the location in spacetime where light rays arrive and where global properties of spacetimes can be measured. Reaching future null infinity is thus very important for extracting correct waveforms. A convenient way to include it in numerical relativity simulations is via hyperboloidal foliations. I will focus on conformal compactification as method to implement free hyperboloidal evolution, in the BSSN / conformal Z4 formulations. After illustrating its advantages, I will report on some ongoing applications in spherical symmetry: an extension to include the Maxwell equations, scattering simulations on a given background, and wave equation(s) evolved on some FLRW -type spacetimes with time-dependent scale factor. I will conclude giving an update on ongoing work in 3D evolutions.
- Speaker: Alex Vañó-Viñuales (IST Lisbon)
- Friday 21 February 2025, 13:00-14:00
- Venue: Potter room.
- Series: DAMTP Friday GR Seminar; organiser: Daniela Cors.
Thu 20 Feb 17:00: Formalising Brauer Group and Group Cohomology in Lean4
=== Hybrid talk ===
Join Zoom Meeting https://cam-ac-uk.zoom.us/j/87143365195?pwd=SELTNkOcfVrIE1IppYCsbooOVqenzI.1
Meeting ID: 871 4336 5195
Passcode: 541180
- Speaker: Jujian Zhang (Imperial College London)
- Thursday 20 February 2025, 17:00-18:00
- Venue: MR14 Centre for Mathematical Sciences.
- Series: Formalisation of mathematics with interactive theorem provers ; organiser: Anand Rao Tadipatri.
Wed 21 May 14:30: Title to be confirmed
Abstract not available
- Speaker: Elisavet Baltas, University of Cambridge
- Wednesday 21 May 2025, 14:30-15:30
- Venue: BAS Seminar Room 330b.
- Series: British Antarctic Survey - Polar Oceans seminar series; organiser: Dr Yohei Takano.
Wed 23 Apr 14:00: Title to be confirmed
Abstract not available
- Speaker: Yingpu Xiahou, University of Auckland
- Wednesday 23 April 2025, 14:00-15:00
- Venue: BAS Seminar Room 330b.
- Series: British Antarctic Survey - Polar Oceans seminar series; organiser: Dr Birgit Rogalla.
Wed 09 Apr 15:00: Title to be confirmed
Abstract not available
- Speaker: Claire Parrott, University of British Columbia
- Wednesday 09 April 2025, 15:00-16:00
- Venue: BAS Seminar Room 2.
- Series: British Antarctic Survey - Polar Oceans seminar series; organiser: Dr Birgit Rogalla.
Wed 19 Mar 14:00: Tipping points of the Ross and Filchner-Ronne Ice Shelves: how worried should we be?
Ocean models consistently project that with sufficient climate change forcing, the Ross and Filchner-Ronne ice shelf cavities could abruptly transition from a cold state to a warm state. Crossing these tipping points would have profound consequences for basal melt rates, buttressing of ice streams, and ultimately sea level rise. Here we analyse over 14,000 years of “overshoot” simulations with the UK Earth System Model, which includes a fully coupled Antarctic Ice Sheet. As the climate warms, stabilises at different temperatures, and cools again, we simulate many examples of the cavities tipping and recovering. We find that global warming thresholds of around 3.5°C and 5°C tip the Ross and Filchner-Ronne respectively. We also find evidence of hysteresis: the climate must cool back down beyond the tipping thresholds in order for each cavity to return to its original cold state. Even if the oceanography recovers, the ice sheet does not: sea level contribution from each catchment takes centuries even to stabilise, and the ice does not begin to regrow on this timescale. Therefore, if the Ross or Filchner-Ronne Ice Shelves cross tipping points, the resulting sea level rise will be effectively irreversible.
- Speaker: Kaitlin Naughten
- Wednesday 19 March 2025, 14:00-15:00
- Venue: BAS Seminar Room 2.
- Series: British Antarctic Survey - Polar Oceans seminar series; organiser: Dr Birgit Rogalla.
Wed 26 Mar 15:30: Title to be confirmed
Abstract not available
- Speaker: Gian Giacomo Navarra, Princeton University
- Wednesday 26 March 2025, 15:30-16:30
- Venue: BAS Seminar Room 330b.
- Series: British Antarctic Survey - Polar Oceans seminar series; organiser: Dr Birgit Rogalla.
Wed 12 Mar 14:00: Title to be confirmed
Abstract not available
- Speaker: Katie Lowry, British Antarctic Survey
- Wednesday 12 March 2025, 14:00-15:00
- Venue: BAS Seminar Room 2.
- Series: British Antarctic Survey - Polar Oceans seminar series; organiser: Dr Birgit Rogalla.
Wed 26 Feb 15:30: Title to be confirmed
Abstract not available
- Speaker: Benjamin Taylor, Scripps Institution of Oceanography
- Wednesday 26 February 2025, 15:30-16:30
- Venue: BAS Seminar Room 1.
- Series: British Antarctic Survey - Polar Oceans seminar series; organiser: Dr Birgit Rogalla.
Tue 04 Mar 11:15: Cygnus X-3 in 2024: many giant radio flares!
Cygnus X-3 is a `high mass X-ray binary’, which was first detected in the early days of X-ray astronomy, in 1966. It is also seen in the radio and the infra-red (but not optically due to obscuration). The emission is due to accretion from the companion star onto the compact source, thought to be a Wolf-Rayet star and a black hole respectively. It occasionally shows giant fares, and has been monitored—approximately daily—for several years with the Arcminute Microkelvin Image (AMI) at Lord’s Bridge, SW of Cambridge. During 2022 and 2023 was placid, with little variation in its radio (or X-ray) emission, but in 2024 it showed five giant radio flares, brightening from a few mJy to > 10 Jy over a few days.
- Speaker: Prof. Dave Green (Cavendish Astrophysics)
- Tuesday 04 March 2025, 11:15-12:00
- Venue: Martin Ryle Seminar Room, Kavli Institute.
- Series: Hills Coffee Talks; organiser: Charles Walker.
Fri 14 Feb 15:30: Discussion on Confidence Intervals for Policy Evaluation in Adaptive Experiments
See the preprint at: https://arxiv.org/pdf/1911.02768
- Speaker: Qingyuan Zhao (Statistical Laboratory)
- Friday 14 February 2025, 15:30-17:00
- Venue: MR5, Centre for Mathematical Sciences, Wilberforce Road, Cambridge.
- Series: Causal Inference Reading Group; organiser: Martina Scauda.