Seminars

Uddipan Banik derives a dynamical account of dark-matter halo density profiles using the Boltzmann–Poisson equations for an expanding Universe populated by subhalos of many masses. A self-similar solution links density slope to halo mass growth; including gravitational scattering and subhalo capture gives gamma = 6/(s + 2). Initial collapse with s = 2 produces a prompt cusp of slope 3/2. Hierarchical growth connects the slope to the primordial power spectrum and recovers the Syer–White relation during matter domination. Stable clustering selects an inner Navarro–Frenk–White cusp of slope one, while stalled accretion approaches the outer slope of three. The framework connects these profiles to successive stages of halo assembly.

Vanessa Siffredi explores why the corpus callosum is central to typical brain development, yet some children born without it or with callosal abnormalities develop comparably to their peers. The talk connects callosal structure and communication between hemispheres with cognition, attention, executive function, memory, language and socio-emotional development. Structural and functional neuroimaging studies of typical development and callosal dysgenesis examine how developing brains compensate for alterations in this major white-matter pathway. Siffredi is affiliated with CHUV and UNIL; Carole Guedj chairs the seminar. Hybrid: Auditoire de pédiatrie Fred Bamatter, HUG, Hôpital des Enfants, Geneva; online via Zoom. Tuesday 29 September 2026, 09:30–10:30 CEST (Europe/Zurich; UTC+2), followed by CIBM news and networking until 11:00. Organized by CIBM Center for Biomedical Imaging — Breakfast and Science. In-person attendance is free without registration. Remote attendees must register through the Zoom link on the event page and select the 29 September occurrence.

Tanmay Vachaspati, joined by Maulik Parikh, explores the limits of knowledge in cosmology and particle physics. The discussion moves from large-scale cosmic structure, the cosmic microwave background and black holes to the Higgs particle, symmetry breaking and magnetic monopoles. These established research landscapes frame questions about what remains unknown and whether some questions could be fundamentally unknowable. This is part of the Beyond Center’s Thinking Beyond series on major questions in science. Speakers: Tanmay Vachaspati and Maulik Parikh, Arizona State University. Organized by the Beyond Center for Fundamental Concepts in Science. Monday 28 September 2026, 18:00 America/Phoenix (Arizona, UTC−07:00). Online via Zoom. Use Register Here on the official event page to complete the event-specific Zoom registration; registration is required. The registration page confirms the date and time.

Lurdes Ondaro Mallea examines whether current models of the kinematic Sunyaev–Zeldovich signal accurately recover diffuse baryons and the strength of astrophysical feedback. The analysis uses hydrodynamic simulations to generate mock stacked measurements for realistic DESI-like galaxy samples, separating contributions from gas density, velocities and nonlinear astrophysics. It tests baryonic changes to density and velocity fields, satellite galaxies, nonlinear velocities and velocity reconstruction. Neglecting satellites can underestimate halo gas fractions at today's measurement precision; further corrections become significant for future datasets. The talk explains how including these effects can improve gas-distribution measurements and assessments of feedback. Online via Zoom. Monday 28 September 2026, 11:00–12:00 PDT (America/Los_Angeles; UTC−7). Follow Join the zoom meeting on the organizer's event page. Lurdes Ondaro Mallea is affiliated with Cambridge. Organized by the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC), Stanford University. This listing advertises the verified remote option.

Irene Rombel discusses how artificial intelligence and machine learning can address bottlenecks, quality issues, and production costs in cell, gene, and RNA therapy manufacturing. The seminar focuses on real-world process-development applications that improve reproducibility, speed, and cost effectiveness.

Paco Villaescusa surveys the growing role of numerical simulations and AI in cosmology. Quijote and Backlight explore how much information about the Universe can be recovered beyond conventional summary statistics, including nonlinear structure and higher-order relationships. CAMELS addresses uncertainty in galaxy formation and other astrophysical processes, while DREAMS examines dark-matter predictions in the presence of baryonic effects. The seminar then considers automated research workflows through Denario, a system that develops hypotheses, plans analyses, writes and executes code, and interprets results. It discusses possibilities opened by combining simulation libraries with coordinated AI systems, while framing these as research directions. The speaker is a computational cosmologist at the Flatiron Institute.

Merav Ahissar examines how expertise emerges through learning the statistics of task-relevant stimuli. Slow learning builds familiarity with stable regularities, such as syllable patterns in language, while fast adaptation supports flexible responses to changing situations, including surprising social interactions. The talk considers atypical learning dynamics in dyslexia and autism and how these may explain difficulties in linguistic and social skill acquisition, respectively. The discussion draws on Gertsovski and Ahissar, Trends in Cognitive Sciences, 2026. Speaker: Merav Ahissar, Edmond and Lily Safra Center for Brain Sciences, Hebrew University of Jerusalem. Organized by Cornell Cognitive Science. Friday 25 September 2026, 15:00–16:30 America/New_York (EDT). Attend online through the public Join via Zoom link on the official event page; the link opens Zoom’s app and browser join options. Cornell advertises the source event as hybrid, but this listing covers the verified online attendance route.

Zack Gelles examines how black-hole rotation twists magnetic fields near light cylinders, where plasma accelerates into inflows and outflows. Semi-analytic models and simulations connect this structure to polarization changes detectable with radio interferometry, offering constraints on black-hole spin and relativistic jets. Kritti Sharma presents fast radio bursts as probes of cosmic baryons. Dispersion measures and secure host redshifts constrain gas in galaxy groups and clusters, while correlations with large-scale structure and other tracers map matter along burst sight-lines. The talk considers how future burst surveys can measure baryonic feedback and its evolution alongside other cosmological observations. Online via Stanford KIPAC Zoom. Friday 25 September 2026, 10:40–11:30 PDT (America/Los_Angeles; UTC−7). Follow Join the zoom meeting on the event page. The organizer lists faculty, staff, members and students as the audience. This is one session with two speakers; individual talk start times are not supplied.

Salvatore Pace discusses the order of anomalies in global symmetries: the number of identical copies needed before their diagonal symmetry becomes anomaly-free. Familiar lattice examples often have finite order, whereas perturbative continuum anomalies have infinite order. The seminar examines Onsager symmetry as a lattice counterpart of chiral symmetry for a massless Dirac fermion in one spatial dimension. Its anomaly has order two, but imposing CPT symmetry on the lattice changes it to infinite order, bringing the lattice description closer to the continuum. The work was carried out with Elijah Lew-Smith and Shu-Heng Shao and is reported in arXiv:2606.12510. Attendance is at the IAS Bloomberg Lecture Hall; the organizer also offers Zoom access by request through the contact listed on the event page.

Srini Devadas examines how hardware and cryptography can strengthen each other. Hardware can protect keys, monitor attacks in real time and reduce the trusted computing base, while hardware vulnerabilities can undermine software security. The talk presents research on accelerating cryptographic computation and using those capabilities to design more efficient protocols. It also asks how cryptography and new security definitions can guide the construction of secure hardware. Devadas is MIT's Webster Professor of Electrical Engineering and Computer Science. Hybrid: MIT Stata Center, Room 32-G449 (Kiva), 32 Vassar Street, Cambridge, MA 02139; online via Zoom. Thursday 24 September 2026, talk at 19:00 EDT (UTC−4); in-person refreshments begin at 18:30. This public event is organized by the Boston Chapter of the IEEE Computer Society and GBC/ACM. Register through the organizer-linked Zoom form for either mode and indicate online or in-person attendance. For physical access, use the Stata Center entrance nearest Main Street, then the fourth-floor elevators.

Mark Harnett presents work on how synaptic organization, nonlinear dendritic processing, and neuronal activity patterns interact to support computation, flexibility, and learning in the adult mammalian neocortex. The Brain and Cognitive Sciences colloquium is followed by a reception.

Lawrence Cheuk presents experiments using laser-cooled polar molecules held in optical-tweezer arrays. Molecular internal states and electric-dipole interactions provide resources for quantum computation, simulation and precision measurement. The talk covers preparation, control and detection of individual molecules; two-qubit operations and deterministic molecular entanglement; and one-dimensional spin simulations. Those experiments examine how spin excitations move, form bound pairs and undergo coherent pair creation and removal. A second set of experiments generates molecular spin-squeezed states and uses spatially resolved measurements to investigate reduced measurement noise, bipartite entanglement and Einstein-Podolsky-Rosen steering. Preliminary progress toward larger arrays may also be discussed. The Donald R. Hamilton Colloquium takes place in Jadwin Hall A-10 at Princeton University.

Farhad Danesh examines how mitochondrial reactive oxygen species, altered metabolism and structural remodelling convert hyperglycaemia into progressive kidney injury. The seminar connects mitochondrial dynamics with diabetic microvascular damage, non-coding RNA regulation and experimental models that establish causal links to disease progression. Genome-wide CRISPR screens and spatial metabolomics reveal cellular gene-regulatory and metabolic changes. Integrating these approaches with molecular genetics, genomics and epigenomics, the work seeks therapeutic targets to prevent diabetic kidney disease progressing to kidney failure. Hybrid: New Research Building Auditorium, Georgetown University Medical Center, Washington, DC, and Zoom. Thursday 24 September 2026, 16:00–17:00 EDT (America/New_York; UTC−4). Use the public event registration form to arrange attendance, or follow its Zoom link for remote participation. Organized by Georgetown’s Distinguished Scientist Seminar Series. Danesh is Professor of Medicine and Chief of Nephrology at MD Anderson.

Leonid Berlyand discusses mathematical models for the onset of cell motion driven by myosin contraction. A two-dimensional free-boundary PDE model links cell-shape evolution to diffusion and Keller–Segel-type transport. The talk examines linear stability, a stability-determining eigenvalue and the way nonlinear diffusion changes the bifurcation from supercritical to subcritical. It also considers the curvature of the bifurcation curve, connections to bistability, and the role of non-self-adjoint operators. An example illustrates why a spectral gap alone need not guarantee stability. This is an in-person Analysis of Fluids and Related Topics seminar at Princeton.

This talk is about the proposal that (1) quantum states that violate the momentum and Hamiltonian constraints represent instances of time, and (2) time evolution corresponds to the gradual collapse of an initial state toward a diffeomorphism-invariant state, driven by stochastic fluctuations of the lapse and shift. During the wavefunction collapse, the scale factor increases monotonically and thus acts as a clock. Scalar, vector, and tensor gravitons arise as physical excitations. In the long-time limit, the tensor gravitons exhibit emergent unitary dynamics, while the extra modes are damped by the non-unitary dynamics that suppress constraint-violating excitations. I will also comment on possible physical implications of these extra graviton modes.

Taillte May investigates how unstable black-hole quasinormal-mode spectra affect observed gravitational-wave signals. Small changes in a gravitational potential can substantially shift the frequencies normally used to test astrophysical black holes. A simple time-domain model reveals a delay before those shifts appear, tied to the echo travel time between the perturbation and the main potential. In the perturbative regime, the frequency change after one echo agrees with the conventional frequency-domain prediction. Beyond that regime, the intermediate waveform cannot be represented by a single constant frequency shift.

James K. Thompson describes how photons repeatedly reflected inside an optical cavity can couple laser-cooled atoms. These collective interactions provide tools for both simulating many-body systems and improving precision measurements. The seminar examines ways to shape the coupling, including exchange and XYZ interactions, interactions involving three or four particles, dissipative processes and protection of coherence through a many-body energy gap. Applications include studying time-dependent phases of superconductors, increasing the sensitivity of matter-wave interferometers and advancing optical clocks. The organizer provides both an Ann Arbor venue and an online attendance option.

Bowen Li explains how ionizable lipids are designed for lipid nanoparticles that deliver messenger RNA. The seminar covers combinatorial and machine-learning-guided design, four-component reactions for rapidly producing lipid libraries, and barcoded screening in living systems to identify formulations targeting organs and cells, including lungs, T cells and tumours. It then examines applications of AI-guided nanoparticle platforms to mRNA therapeutics. Li is an Associate Professor and Canada Research Chair at the University of Toronto's Leslie Dan Faculty of Pharmacy. Online via Zoom. Thursday 24 September 2026, 11:00–12:00 Eastern Daylight Time (America/New_York; UTC−4). Use Join via Zoom on Western University's event page. The stated audience includes researchers, students, alumni and the general public. Organized by Western University's Western Bioinformatics Research Seminar.

Massive stars are among the most influential engines in the Universe, shaping their surroundings through radiation, winds, and supernovae driving turbulence, regulating star and planet formation, and seeding the next generations of stars. Their feedback not only sculpts the interstellar medium of galaxies but also sets key boundary conditions for processes that concern nearly every branch of astrophysics: the baryon cycle (an essential ingredient in galaxy evolution across cosmic time), the progenitor environments of gravitational wave sources, the chemical and dynamical histories of planetary systems, and the magnetic and radiative feedback mechanisms that regulate the lifetimes of molecular clouds.Despite this central role, our quantitative understanding of how feedback operates across different galactic environments – and across the history of the Universe – remains limited. This is now changing. Over the past decade, optical integral field units (IFUs) have enabled a revolution in resolved feedback studies, allowing us to simultaneously map the feedback-driving stars and the interstellar medium they energize across entire galaxies. I will present results mostly (nut not exclusively) from large IFU surveys of nearby galaxies that empirically link stellar feedback efficiency to local environmental conditions — from dwarf starburst galaxies to massive disks. I will discuss how these findings inform topics ranging from cosmic reionization to binary evolution pathways and planet-forming environments, and I will highlight how IFU datasets are unexpectedly revealing new, serendipitous phenomena that challenge our feedback models and open fresh discovery space across astrophysics.

Savina Cammalleri discusses extending DISCO, a digital microfluidic platform for single-cell omics, to protein analysis. The work uses controlled handling of individual cells and samples to make proteomic measurements more efficient and scalable. The presentation considers how a flexible microfluidic approach can support studies of variation between cells and the molecular processes underlying that variation. Its goal is to broaden the experimental tools available for biological measurements at single-cell resolution. Cammalleri is a doctoral researcher in biomedical engineering at the University of Toronto and conducts her research at the Max Planck Institute for Multidisciplinary Sciences.