Links to Colloquia

Past years' colloquia

List of past colloquia videos (Restricted: Only members of the Brandeis community can view this list and access the videos)

Eisenbud Lecture Series in Mathematics and Physics

Berko Symposium

All colloquium videos are under copyright and may not be reproduced, in part or in total, without written permission of the speaker and of the Physics Department.

Department Colloquia

Martin Weiner Lecture Series
Department of Physics Colloquium
4 pm, Abelson 131
Refreshments at 3:30 pm outside Abelson 131

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Fall 2017 Colloquia

Tuesday, September 5, 2017
Margaret Johnson, Johns Hopkins University
"Protein self-assembly in the cell: Spatial and temporal control through membrane localization"
Host: Michael Hagan
Abstract: Cell division, endocytosis, and viral budding would not function without the localization and assembly of protein complexes on membranes. What is poorly appreciated, however, is that by localizing to membranes, proteins search in a reduced space that effectively drives up concentration. We have derived an accurate and practical analytical theory to quantify the significance of this dimensionality reduction in regulating protein assembly on membranes. We define a simple metric, an effective equilibrium constant, that allows for quantitative comparison of protein-protein interactions with and without membrane present. We find that many of the protein-protein interactions between pairs of proteins involved in clathrin-mediated endocytosis in human and yeast cells can experience enormous increases in effective protein-protein affinity (10-1000 fold) due to membrane localization. By developing new methods for reaction-diffusion simulation of protein structures, we further characterize the non-equilibrium dynamics of these assembly processes, with reaction parameters defined from experiment. Both theory and simulations highlight the power of membrane localization in triggering robust protein-protein binding, suggesting that it can play an important role in controlling the timing of endocytic protein coat formation.

Tuesday, September 12, 2017
Michael Hagan, Brandeis University
Host: Physics Department
"How to control the size of a self-assembling, self-filling shell"
Abstract: The self-assembly of a protein shell around a cargo is a common mechanism of encapsulation in biology. For example, many viruses assemble an icosahedral protein shell (capsid) around the the viral nucleic acid. Some viruses then acquire an additional exterior coating by budding through a cell membrane. Similarly, bacterial microcompartments (BMCs) are large icosahedral protein shells that assemble around collections of enzymes to act as organelles inside of bacteria.

In this talk I will use coarse-grained computational models and simple scaling calculations to illuminate the factors that control such a self-assembly process. I will particularly focus on how material properties (such as nucleic acid electric charge, membrane bending modulus, or enzyme cohesive forces) control assembly pathways and the size of the assembled shell.

Tuesday, September 19, 2017
Daniel Whiteson, University of California, Irvine & Jorge Cham, PHD Comics
"We Have No Idea"
Host: Bjoern Penning
Abstract: Jorge and Daniel will talk about the big unsolved mysteries of the Universe, including dark matter, dark energy, and the behavior of cats. A fun presentation that combines science, humor, and live drawing, inspired by their new book.

Tuesday, September 26, 2017
Dapeng Bi, Northeastern University
"Mechanics of Epithelial Tissues: Structure, Rigidity and Fluidity"
Host: Bulbul Chakraborty
Abstract: Cells must move through tissues in many important biological processes, including embryonic development, cancer metastasis, and wound healing. Often these tissues are dense and a cell's motion is strongly constrained by its neighbors, leading to glassy dynamics. Although there is a density-driven glass transition in particle-based models for active matter, these cannot explain liquid-to-solid transitions in confluent tissues, where there are no gaps between cells and the packing fraction remains fixed and equal to unity. I will demonstrate the existence of a new type of rigidity transition that occurs in confluent tissue monolayers at constant density.  The onset of rigidity is governed by a model parameter that encodes single-cell properties such as cell-cell adhesion and cortical tension. I will also introduce a new model that simultaneously captures polarized cell motility and multicellular interactions in a confluent tissue and identify a glassy transition line that originates at the critical point of the rigidity transition. This work suggests an experimentally accessible structural order parameter that specifies the entire transition surface separating fluid tissues and solid tissues. 

Tuesday, October 3, 2017

No colloquium (Brandeis Thursday)

Tuesday, October 10, 2017
Tulika Bose, Boston University
"Unlocking the mysteries of the Universe with the CMS experiment at the Large Hadron Collider"
Host: Bjoern Penning
Abstract: The discovery of the Higgs Boson at the Large Hadron Collider (LHC) in 2012 was a ground-breaking event in particle physics history. The LHC has restarted recently at an unprecedented center of mass energy of about 13 TeV and the data collected by the CMS experiment is expected to help fully understand the nature of electroweak symmetry breaking and potentially discover new physics. In this talk, I will review recent results from the CMS experiment with special focus on searches for physics beyond the Standard Model.

Tuesday, October 17, 2017
Elizabeth Blanton, Boston University
"Extragalactic Jets as Probes of Clusters of Galaxies"
Host: John Wardle
Abstract: I will present multi-wavelength (X-ray, optical, infrared, and radio) observations of clusters of galaxies, including in-depth study of nearby objects and a survey of distant systems. Cooling of the hot, gaseous intracluster medium in cluster centers can feed the supermassive black holes in the cores of the dominant cluster galaxies leading to active galactic nucleus (AGN) outbursts. This AGN feedback can reheat the gas, stopping cooling and large amounts of star formation. Most relaxed, cool core clusters host powerful AGN in their central galaxies and these AGN can significantly affect the distribution of e.g., temperature and abundance on cluster scales. AGN heating can come in the form of shocks, buoyantly rising bubbles that have been inflated by radio jets and lobes, and sound wave propogation. Sloshing of the cluster gas, related to minor, off-center interactions with galaxy sub-clusters or groups also affects the distribution of temperature and abundance on large scales. This sloshing gas can interact with the AGN's radio-emitting jets and lobes causing them to bend. This bending is also found in AGN jets and lobes embedded in clusters undergoing major, head-on cluster, cluster mergers. Since this bending is a signature of interaction within clusters, bent, double-lobed AGN observed in the radio can be used as beacons for clusters of galaxies at high redshifts. I will describe our large sample of high-redshift, bent-double radio sources that were observed in the infrared with the Spitzer Space Telescope and in the optical with the Discovery Channel Telescope and that have yielded approximately 200 new, distant clusters of galaxies. The clusters in our survey ("COBRA," Clusters Occupied by Bent Radio AGN) will serve as important laboratories for studying galaxy evolution.

Tuesday, October 24, 2017
Stephon Alexander, Brown University
"The Jazz of Physics: The Link Between Music and The Structure of the Universe"
Host: Bjoern Penning
Abstract: In this talk Alexander revisits the interconnection between music and the evolution of astrophysics and the laws of motion. He explores new ways music, in particular jazz music, mirrors modern physics, such as quantum mechanics, general relativity, and the physics of the early universe. Finally, he discusses ways that innovations in physics have been and can be inspired from "improvisational logic" exemplified in Jazz performance and practice.

Tuesday, October 31, 2017
Huajian Gao, Brown University
"Mechanics of Cell-Nanomaterials Interaction"
Host: Michael Hagan
Abstract: Nanomaterials, including various types of nanoparticles, nanowires, nanofibers, nanotubes, and atomically thin plates and sheets have emerged as candidates as building blocks for the next generation electronics, microchips, composites, barrier coatings, biosensors, drug delivery, and energy harvesting and conversion systems. There is now an urgent societal need to understand the biological interactions and environmental impact of nanomaterials which are being produced and released into the environment by nearly a million tons per year. This talk aims to discuss mechanics as an enabling tool in this emerging field of study. The discussions will touch on some of the recent experimental, modelling and simulation studies on the mechanisms of cell uptake of low-dimensional nanomaterials and their effects on subcellular vesicles and damage.

Tuesday, November 7, 2017
Narayanan Menon, UMass Amherst
Host: Michael Hagan
"Flexibility and Form: Emergence of Shape in Thin Sheets"
Abstract: Thin sheets assume a rich diversity of shapes in the natural world, ranging from folds on the earth’s crust, to the wavy shapes of leaves and flowers, down to more microscopic biomembranes and synthetic thin films. We have used thin polymer films floating on the surface of a fluid as a venue in which to study the emergence of complex shapes via successive elastic instabilities. Understanding these patterns required new notions of ‘thinness’ or bendability of a sheet, which define regimes in which textbook theories of post-buckling fails. I will end by describing opportunities for wrapping and encapsulation in this new regime of highly-bendable materials.

Tuesday, November 14, 2017
Julie Williams-Byrd, NASA Langley Research Center
"Decision Analysis Methods Used to Make Appropriate Investments in Human Exploration Capabilities and Technologies"
Host: Anique Olivier-Mason
Abstract: NASA is transforming human spaceflight. The Agency is shifting from an exploration-based program with human activities in low Earth orbit (LEO) and targeted robotic missions in deep space to a more sustainable and integrated pioneering approach. Through pioneering, NASA seeks to address national goals to develop the capacity for people to work, learn, operate, live, and thrive safely beyond Earth for extended periods of time. However, pioneering space involves daunting technical challenges of transportation, maintaining health, and enabling crew productivity for long durations in remote, hostile, and alien environments. Prudent investments in capability and technology developments, based on mission need, are critical for enabling a campaign of human exploration missions. There are a wide variety of capabilities and technologies that could enable these missions, so it is a major challenge for NASA’s Human Exploration and Operations Mission Directorate (HEOMD) to make knowledgeable portfolio decisions. It is critical for this pioneering initiative that these investment decisions are informed with a prioritization process that is robust and defensible. It is NASA’s role to invest in targeted technologies and capabilities that would enable exploration missions even though specific requirements have not been identified. To inform these investments decisions, NASA’s HEOMD has supported a variety of analysis activities that prioritize capabilities and technologies. These activities are often based on input from subject matter experts within the NASA community who understand the technical challenges of enabling human exploration missions.

This paper will review a variety of processes and methods that NASA has used to prioritize and rank capabilities and technologies applicable to human space exploration. The paper will show the similarities in the various processes and showcase instances where customer specified priorities force modifications to the process. Specifically, this paper will describe the processes that the NASA Langley Research Center (LaRC) Technology Assessment and Integration Team (TAIT) has used for several years and how those processes have been customized to meet customer needs while staying robust and defensible.

Tuesday, November 21, 2017

No colloquium (Thanksgiving week)

Monday, November 27 to Wednesday, November 29, 2017
Eisenbud Lecture Series in Mathematics and Physics
James Sethna, Cornell University
Host: Bulbul Chakraborty

Monday, November 27, 2017 (Lecture I), 4:00pm, Gerstenzang 121
"Sloppy Models, Differential Geometry, and How Science Works"
James P. Sethna, Katherine Quinn, Archishman Raju, Mark Transtrum, Ben Machta, Ricky Chachra, Ryan Gutenkunst, Joshua J. Waterfall, Fergal P. Casey, Kevin S. Brown, Christopher R. Myers
Abstract: Models of systems biology, climate change, ecosystems, and macroeconomics have parameters that are hard or impossible to measure directly. If we fit these unknown parameters, fiddling with them until they agree with past experiments, how much can we trust their predictions? We have found that predictions can be made despite huge uncertainties in the parameters – many parameter combinations are mostly unimportant to the collective behavior. We will use ideas and methods from differential geometry to explain what sloppiness is and why it happens so often. We show that physics theories are also sloppy – that sloppiness may be the underlying reason why the world is comprehensible.

Tuesday, November 28, 2017 (Lecture II), 4:00pm, Abelson 131
"Crackling Noise"
James P. Sethna
Abstract: A piece of paper or candy wrapper crackles when it is crumpled. A magnet crackles when you change its magnetization slowly. The earth crackles as the continents slowly drift apart, forming earthquakes. Crackling noise happens when a material, when put under a slowly increasing strain, slips through a series of short, sharp events with an enormous range of sizes. There are many thousands of tiny earthquakes each year, but only a few huge ones. The sizes and shapes of earthquakes show regular patterns that they share with magnets, plastically deformed metals, granular materials, and other systems. This suggests that there must be a shared scientific explanation. We shall hear about crackling noise and that it is a symptom of a surprising truth: the system has emergent scale invariance – it behaves the same on small, medium, and large lengths. 

Wednesday, November 29, 2017 (Lecture III), 10:00am, Abelson 333
"Normal Form for Renormalization Groups: The Framework for the Logs"
James P. Sethna, Archishman Raju, Colin Clement, Lorien Hayden, Jaron Kent-Dobias, Danilo Liarte, and Zeb Rocklin
Abstract: Ken Wilson’s renormalization group solved for the behavior of phase transitions by mapping statistical mechanics into a differential equation in the space of all Hamiltonians, as we examine them on different length scales. This mapping from complex physical systems to simple differential equations has allowed us to explain scale invariance that emerges in everything from crackling noise to the onset of chaos. The results of the renormalization group are commonly advertised as the existence of power law singularities near critical points. This classic prediction is often violated, with logarithms and exponentials that pop up in the most interesting cases. Mathematicians have developed normal form theory to describe the likely behaviors of differential equations. We use normal form theory to systematically group these seeming violations into universality families. We recover and explain the existing literature, predict the nonlinear generalization for universal homogeneous functions, and show that the procedure leads to a better handling of the singularity even for the classic 4-d Ising model.

Tuesday, December 5, 2017
Roxanne Guenette, Harvard University
Host: Bjoern Penning
Title: Neutrinos: from zeros to heroes?
Abstract: The Standard Model, that describes extremely well the particles and their interactions, predicts that neutrinos are massless and only interacts via weak interaction. These properties made neutrinos some of the least interesting particles of the model... until the discovery that they oscillate. This groundbreaking result implies that neutrinos are massive particles and opens the door to physics beyond the Standard Model- the holy grail of particle physicists. In addition, it seems that neutrinos could hold the key to many great mysteries of physics, such as the imbalance in the Universe between matter and anti-matter, and these are now within the reach of the next generation of neutrino experiments. After reviewing the intriguing properties of neutrinos, I will present the open questions in neutrino physics and describe how current and future neutrino experiments, focusing on Liquid Argon experiments, can bring new answers. 

Spring 2018 Colloquia

Tuesday, January 16, 2018


Tuesday, January 23, 2018


Tuesday, January 30, 2018


Tuesday, February 6, 2018


Tuesday, February 13, 2018


Tuesday, February 20, 2018

No Colloquium (Midterm Recess)

Tuesday, February 27, 2018

Philip Nelson, University of Pennsylvania
Host: Jané Kondev

Tuesday, March 6, 2018

No colloquium (APS)

Tuesday, March 13, 2018
Rachel Mandelbaum, Carnegie Mellon University
Host: Marcelle Soares-Santos

Tuesday, March 20, 2017
David Pritchard, Massachusetts Institute of Technology
Host: Matthew Headrick

Tuesday, March 27, 2018
Anushya Chandran, Boston University
Host: Matthew Headrick

Tuesday, April 3, 2018

No colloquium: Passover and spring recess

Tuesday April 10, 2018
Washington Taylor, Massachusetts Institute of Technology
Host: Matthew Headrick

Tuesday, April 17, 2018


Tuesday, April 24, 2018