Physics and Astronomy - Colloquium Schedule
Colloquia are presented on Thursdays at 3:45 pm in Room 245 of the Physics Building, unless otherwise noted.
Refreshments are served at 3:30 pm.
Thursday, January 18, 2018
Speaker: Shanshan Cao, Wayne State University
Title: Probing the Quantum Chromodynamic fluid with relativistic nuclear collisions
Abstract: Nuclear matter is heated beyond two trillion degrees in relativistic heavy-ion collisions and becomes a strongly coupled plasma of quarks and gluons. This highly excited quark-gluon plasma (QGP) matter displays properties of perfect fluid and is believed similar to the state of the early universe microseconds after the big bang. In this talk, high-energy particles and jets are utilized to probe the QGP properties. A linear Boltzmann transport coupled to hydrodynamic model is established to describe the strong interaction between energetic partons and the QGP. This includes diverse microscopic processes for both massless and massive parton scatterings, and provides a simultaneous description of the nuclear modification of heavy and light flavor hadrons observed at the RHIC and LHC experiments. To precisely extract transport coefficients of the QGP, a statistical analysis framework that includes machine learning and Bayesian methods is developed, which brings a paradigm shift in statistical comparisons between theory and experiment.
Thursday, January 25, 2018
Speaker: ChunNing (Jeanie) Lau, Ohio State University
Title: Spin, Charge and Heat Transport in Low-Dimensional Materials
Abstract: Low dimensional materials constitute an exciting and unusually tunable platform for investigation of both fundamental phenomena and electronic applications. Here I will present our results on transport measurements of high quality few-layer phosphorene devices, the unprecedented current carrying capacity of carbon nanotube "hot dogs", and our recent observation of robust long distance spin transport through the antiferromagnetic state in graphene.
About the speaker: Dr. Chun Ning (Jeanie) Lau is a Professor in the Department of Physics at The Ohio State University. She received her BA in physics from University of Chicago in 1994, and PhD in physics from Harvard in 2001. She was a research associate at Hewlett Packard Labs in Palo Alto from 2002 to 2004, before joining University of California, Riverside in 2004 as an assistant professor. She was promoted to associate professor in 2009 and full professor in 2012. Starting January 2017 she moved to The Ohio State University. Her research focuses on electronic, thermal and mechanical properties of nanoscale systems, in particular, graphene and other two-dimensional systems.
Tuesday, January 30, 2018 (NOTE SPECIAL DATE)
Speaker: Vladimir Skokov, Brookhaven National Lab
Title: Quantum ChromoDynamics in extreme conditions
Abstract: In my talk, I discuss two landscapes of Quantum ChromoDynamics (QCD), the theory of strong interactions, in extreme conditions. I start with hot and dense QCD, which can be probed in the collisions of heavy-ions at high energy. The goal of the heavy-ion program is to map and study the QCD phase diagram and establish the existence of a conjectured critical point in QCD. The identification of this prominent landmark in the phase diagram is possible owing to its unique signature. I argue that recent experimental measurements agree with the theoretical expectations and, if confirmed, may lead to the discovery of a QCD critical point. I then turn to the landscape of cold QCD to be probed at a future Electron-Ion Collider. I discuss one of the exciting features which is the linear polarization of strong quasi-classical gluon fields in an unpolarized nucleus.
Thursday, February 1, 2018
Speaker: Li Yan, McGill University
Title: A droplet of QGP in the little bang
Abstract: One of the fundamental questions in high energy nuclear physics is how to understand the dynamics of matter systems dominated by strong interactions. Especially, in systems where temperatures are comparable to the QCD energy scale (~10^12 K), such as the universe in the first microseconds after Big Bang, or in high energy heavy-ion collisions carried out at RHIC and the LHC (the Little Bang), our interest is in a novel state of matter -- quark-gluon plasma (QGP). One of the significant properties of QGP is its perfect fluidity. Actually, the value of shear viscosity over entropy density ratio of QGP has been found to be very close to a theoretical lower bound. The fluidity the QGP plays an essential role in the present studies of heavy-ion experiments. QGP evolution dominates the observed correlation behaviors of the produced particles in nucleus-nucleus collisions (large colliding systems), proton-lead and even proton-proton collisions (small colliding systems). In this talk, I will demonstrate how the idea of QGP fluidity emerges from the observed phenomena in experiments. I will also explain how a "standard model" of heavy-ion collisions based on relativistic hydrodynamics is challenged by the fluid behavior in recent small colliding systems.
Thursday, February 8, 2018
Speaker: Chun Shen, Brookhaven National Lab
Title: Going with the flow — the nuclear phase diagram at the highest temperatures and densities
Abstract: The nuclear matter has a complex phase structure, with a deconfined Quark-Gluon Plasma (QGP) expected to be present under conditions of extreme pressure and temperature. The hot QGP filled the universe about few microseconds after the Big Bang. This hot nuclear matter can be generated in the laboratory via the collision of heavy atomic nuclei at high energy. I will review recent theoretical progress in studying the transport properties the QGP. Recently, the Relativistic Heavy-Ion Collider (RHIC) conducted the beam energy scan experiments. It offered a unique opportunity to study the nuclear phase diagram in a hot and baryon-rich environment. I will focus on the development of a comprehensive framework that is able to connect the fundamental theory of strong interactions with the RHIC experimental observables. This dynamical framework paves the way for quantitative characterization of the QGP and for locating the critical point in the nuclear phase diagram. These studies will advance our understanding of strongly interacting many-body systems and build interconnections with other areas of physics, including string theory, cosmology, and cold atomic gases.
Thursday, February 15, 2018
Speaker: Mauricio Guerrero, North Carolina State University
Title: Out of equilibrium dynamics: Lessons from Nuclear Collisions
Abstract: The current knowledge of the universe is highly constrained without understanding the formation of baryonic matter widely observed today. It is then required to know the precise details of the transition where a highly dense plasma composed by quarks, antiquarks, and gluons combine to form hadrons. Ultrarelativistic heavy ion experiments can recreate non-equilibrium extreme conditions of the early universe by colliding heavy nuclei moving nearly at the speed of light. One of the major scientific discoveries of this century is the observation of a tiny, short-lived quark-gluon plasma (QGP). This extreme state of matter behaves like a liquid with a very small viscosity. Recently, we have learned that the perfect fluidity property, observed first in nucleus-nucleus collisions, also extends to proton-nucleus and proton-proton collisions. The "nearly perfect liquid" behavior of the QGP has opened up a new avenue for studying transport properties of strongly interacting systems. Nonetheless, these experimental findings challenge the theorists to develop better models which include the non-equilibrium evolution of the expanding nuclear matter created in those collisions. In this talk, I will review the 'standard model picture' of heavy ion collisions and present some recent theoretical studies which attempt to explain the unreasonable phenomenological success of fluid dynamical models in far from local equilibrium situations. I shall pose several unanswered questions about the QGP which emerge from these new theoretical developments and discuss how in the next few years, future experimental programs at large baryon densities and energy regimes will herald a new era of discovery and unraveling of the secrets of QGP.
Thursday, February 22, 2018
Speaker: Hong Guo, McGill University
Title: Electronic States of the Moiré superlattice
Abstract: Two-dimensional (2D) van der Waals (vdW) heterostructures have attracted great attention in the past five years. By stacking different 2D materials to bond via the vdW force, these artificial heterostructures provide interesting and new material phase space for exploration. In this talk I shall focus on one aspect of the 2D vdW materials: the Moiré pattern. In visual arts, Moiré pattern is an optical perception of a new pattern formed on top of two similar stacking patterns. In 2D vdW heterostructures, the Moiré pattern is a physical superlattice which brings about novel electronic properties. To theoretically predict the physical properties of the Moiré superlattice, systems containing more than ten thousand atoms often need to be analyzed by first principles. In this talk I shall begin by briefly discussing how one may break the "size limit" so that very large first principles simulations within the density functional theory can be carried out. Afterward, I shall present and discuss some of the calculated novel properties of the Moiré superlattice: the emergence of a secondary Dirac cone, the suppression of the carrier mobility, and the formation of multiple helical valley currents, on various 2D vdW heterostructure materials. Some of these properties can well be the basis of potential applications.
About the speaker: Dr. Hong Guo obtained B.Sc. in Physics at the Sichuan Normal University in China and Ph.D. in theoretical condensed matter physics at the University of Pittsburgh. In 1989, he joined the faculty of the Physics Department, McGill University in Montreal Canada. He is currently a James McGill Professor of Physics. His research includes quantum transport theory, nanoelectronic device physics, nonequilibrium phenomena, materials physics, density functional theory, mathematical and computational physics. He was elected to Fellow of the American Physical Society in 2004, and Fellow of the Royal Society of Canada (Academy of Sciences) in 2007. He received the Killam Research Fellowship Award from the Canadian Council for the Arts in 2004; the Brockhouse Medal for Excellence in Experimental or Theoretical Condensed Matter Physics of the Canadian Association of Physicists in 2006; and the CAP-CRM Prize in Theoretical and Mathematical Physics from Canadian Association of Physicists in 2009.
Friday, March 2, 2018 (Note Special Colloquium Date)
Speaker: David Ceperley, University of Illinois at Urbana-Champaign, and member of the National Academy of Sciences
Title: How can we model the hydrogen inside Jupiter and Saturn?
Abstract: Jupiter, Saturn and a host of newly discovered exoplanets are thought to be composed largely of hydrogen and helium. To understand the planets, we need properties of hydrogen and helium under the extreme conditions of temperature and pressure inside those planets, conditions hardly accessible to laboratory measurements. I will describe how we use high performance computers to calculate those properties and thus help understand some of the most important objects in the Universe.
About the speaker: Dr. David Ceperley is the Founder and Blue Waters Professor of Physics at University of Illinois Urbana-Champaign, and a member of the National Academy of Sciences. He received his BS in physics from the University of Michigan in 1971 and his Ph.D. in physics from Cornell University in 1976. After one year at the University of Paris and a second postdoc at Rutgers University, he worked as a staff scientist at both Lawrence Berkeley and Lawrence Livermore National Laboratories. In 1987, he joined the Department of Physics at Illinois. He was a staff scientist at the National Center for Supercomputing Applications from 1987 until 2012. Professor Ceperley is a Fellow of the American Physical Society and a member of the American Academy of Arts and Sciences, and was elected to the National Academy of Sciences in 2006. He has received many honors and awards; see https://physics.illinois.edu/people/directory/profile/ceperley
Tuesday, March 6, 2018 (NOTE SPECIAL DATE AND TIME: 2:30pm)
Speaker: LongGang Pang, Lawrence Berkeley National Laboratory
Title: Exploring the quantum chromodynamics phase transition with deep learning
Abstract: The state-of-the-art pattern recognition method in machine learning (deep convolution neural network) has been used to classify two different phase transitions between normal nuclear matter and hot-dense quark gluon plasma. Big amount of training data is prepared by simulating heavy ion collisions with the most efficient relativistic hydrodynamic program CLVisc. High level correlations of particle spectra in transverse momentum and azimuthal angle learned by the neural network are quite robust in deciphering the transition type in the quantum chromodynamics phase diagram. Through this study we demonstrated that there is a traceable encoder of the phase structure that survives the dynamical evolution and exists in the final snap shot of heavy ion collisions and one can exclusively and effectively decode these information from the highly complex output using machine learning.
Thursday, March 8, 2018
Speaker: Christoph Naumann, Indiana University - Purdue University Indianapolis
Title: Probing membrane protein organization and dynamics in planar model membranes using single molecule-sensitive confocal detection techniques
Abstract: The organization and distribution of proteins in the plasma membrane is widely known to influence membrane protein functionality. However, it remains challenging to decipher the underlying mechanisms that regulate membrane protein properties in the complex environment of cellular membranes. To overcome these challenges, an experimental strategy is discussed, in which the distribution, oligomerization state, and mobility of membrane proteins can be explored in a planar polymer-tethered lipid bilayer of well-defined lipid compositions using single molecule-sensitive confocal detection strategies. Results from such model membrane experiments are presented, which explore the influence of native ligands, bilayer asymmetry, and cholesterol content on the sequestration/oligomerization of urokinase plasminogen activator receptors (uPAR) and integrins [1-4]. Moreover, dual-color confocal experiments are described, which provide information about the formation and composition of uPAR-integrin complexes and the role of membrane cholesterol therein. Polymer-tethered lipid bilayer systems, comprised of phospholipids and lipopolymers, are also characterized by remarkable materials properties, which make them suitable as cell surface-mimicking substrates for the analysis of adhesion and spreading of plated cells. To illustrate the feasibility of such an application, we discuss the assembly of cadherin chimera into clusters on the surface of a polymer-tethered lipid bilayer substrate to form stable cell-substrate cadherin linkages underneath migrating C2C12 myoblasts . Cluster tracking experiments reveal the cytoskeleton-regulated long-range mobility of cell-substrate linkages, thereby displaying remarkable parallels to the dynamics of cadherin-based cell-cell junctions.
 A. P. Siegel et al. (2011) Biophys. J. 101, 1642.
 N. F. Hussain et al. (2013) Biophys. J. 104, 2212.
 Y. Ge et al. (2014) Biophys. J. 107, 2101.
 Y. Ge et al. (2018) Biophys. J. 114, 158.
 Y. Ge et al. (2016) Soft Matter 12, 8259.
Thursday, March 15, 2018
No Colloquium - Spring break
Thursday, March 22, 2018
Speaker: W.J. Llope, Wayne State University
Title: How to give a great talk - tips for success and traps to avoid
Abstract: Whether your future lies in academia or industry, you will have opportunities to present your recent work while standing in front of an audience of interested people. Giving a good talk is a very powerful advertisement of you and your efforts, and, if you can properly enthuse the audience during your talk, the subsequent discussions can be very helpful for your future work. Great talks come in many forms, but all share a few key positive aspects and all avoid some (unfortunately rather common) pitfalls. This colloquium will share some tips from what I've learned over the years while watching thousands of talks, and giving a few myself. This presentation is specifically aimed at our students and postdocs, although the faculty are of course welcome to share their insights as well. The atmosphere will be informal and an open discussion, especially with our younger colleagues, will be encouraged.
Thursday, March 29, 2018
Speaker: Vladimir Chernyak, Department of Chemistery, Wayne State University
Title: Integrability in Non-Equilibrium Quantum Dynamics
Thursday, April 5, 2018
Speaker: Aaron Pierce, University of Michigan
Thursday, April 12, 2018
No Colloquium -- Graduate Research Day
Thursday, April 19, 2018 (Vaden Miles Lecture)
Speaker: J. Michael Kosterlitz, Brown University (2016 Nobel Prize in Physics)
Location: Spencer M. Partrich Auditorium, Wayne State University Law School
Title: Topological Defects and Phase Transitions - A Random Walk to the Nobel Prize
Abstract: This talk is about my path to the Nobel Prize and reviews some of the applications of topology and topological defects in phase transitions in two-dimensional systems for which Kosterlitz and Thouless split half the 2016 Physics Nobel Prize. The theoretical predictions and experimental verification in two dimensional superfluids, superconductors and crystals will be reviewed because they provide very convincing quantitative agreement with topological defect theories.
About the speaker: Dr. J. Michael Kosterlitz is a theoretical physicist recognized for his work with David J. Thouless on the application of topological ideas to the theory of phase transitions in two-dimensional systems with a continuous symmetry. The theory has been applied to thin films of superfluid 4He, superconductors and to melting of two-dimensional solids. This work was recognized by the Lars Onsager prize in 2000, membership in the AAAS 2007, and by the 2016 Nobel Prize in Physics. Dr. Kosterlitz graduated from Cambridge University earning a BSc in physics in 1965, an MA in 1966, and received a D. Phil. from Oxford in 1969. He was a postdoctoral fellow at Torino University, Italy, in 1970 and at Birmingham University, U.K., from 1970-73. There he met David Thouless and together they did their groundbreaking work on phase transitions mediated by topological defects in two dimensions. He was a postdoctoral fellow at Cornell in 1974, on the faculty at Birmingham 1974-81, Professor of Physics at Brown University 1982 – present, and elected to the National Academy of Sciences in 2017.
Thursday, September 7, 2017
Speaker: Victor Yakovenko, University of Maryland
Title: Economic inequality from a statistical physics point of view
Abstract: By analogy with the probability distribution of energy in statistical physics, the probability distribution of money among the agents in a closed economic system is expected to follow the exponential Boltzmann-Gibbs law, as a consequence of entropy maximization. Analysis of empirical data shows that income distributions in the USA, European Union, and other countries exhibit a well-defined two-class structure. The majority of the population (about 97%) belongs to the lower class characterized by the exponential ("thermal") distribution. The upper class (about 3% of the population) is characterized by the Pareto power-law ("superthermal") distribution, and its share of the total income expands and contracts dramatically during booms and busts in financial markets. Such a two-class distribution can be obtained analytically for a combination of additive and multiplicative stochastic processes. Globally, data analysis of energy consumption (and CO2 emission) per capita around the world in the last 30 years shows decreasing inequality and convergence toward the exponential probability distribution, in agreement with the maximal entropy principle. All papers are available at http://physics.umd.edu/~yakovenk/econophysics/.
Thursday, September 14, 2017 (Note special location)
Speaker: Kip Thorne
Location: Spencer M. Partrich Auditorium, Wayne State University Law School
Title: Geometrodynamics: Exploring the nonlinear dynamics of curved spacetime via computer simulations and gravitational wave observations
Abstract: A half century ago, John Wheeler challenged his students and colleagues to explore Geometrodynamics: the nonlinear dynamics of curved spacetime. How does the curvature of spacetime behave when roiled in a storm, like a storm at sea with crashing waves. Dr. Thorne and collaborators tried to explore this, and the failed. Success eluded us until two new tools became available: computer simulations, and gravitational wave observations. Dr. Thorne will describe what these have begun to teach us, and he will offer a vision for the future of Geometrodynamics.
About the speaker: Kip Thorne is the Richard P. Feynman Professor of Theoretical Physics, Emeritus, at the California Institute of Technology in Pasadena, California. He is a theoretical physicist specializing in the astrophysical effects of Einstein's General Theory of Relativity, especially black holes and gravitational waves. He was one of the founding members of the Laser Interferometer Gravitational Wave Observatory (LIGO) in 1984. The goal of LIGO is to observe gravitational waves from extreme astrophysical events. Gravitational waves were first predicted by Albert Einstein one-hundred years ago this year. While there is good indirect evidence for gravitational waves based on the behavior of binary pulsars, the first direct measurement of a gravitational wave was announced by the LIGO team on February 11, 2016. Two independent laser interferometers in Livingston, Louisiana and Hanford, Washington observed a gravitational wave on September 14, 2015. Analysis of the signal indicates the wave was produced by the collision of two black holes more than one-billion light years away. Professor Thorne is an accomplished author of books for scientists and the general public, and he was the scientific consultant and Executive Producer of the film Interstellar.
A video of this colloquium may be found HERE (YouTube)
Thursday, September 21, 2017
Speaker: Boris Yakobson, Rice University
Title: Predictive modeling of low-dimensional materials, nanotubes, graphene, and beyond
Abstract: Comprehensive tools of materials modeling are derived from the principles of physics and chemistry, empowered by high performance computing. Together, this allows one to make verifiable predictions of novel physical structures with specific, often useful or even extraordinary, properties. Nanotubes offer one such lesson , where atomic makeup and defects dynamics lead to the understanding of their strength and failure physics on one hand, while also reveal the origins of chiral symmetry in nano-carbon synthesis . A second, very recent, example is the prediction of pure mono-elemental 2D boron, its particular structures to form on Ag(111), which culminated in recent experimental confirmations. We may also mention, if time permits, its physical properties like new 2D-superconductor , now-detected Dirac cone dispersion, still-sought 2D-plasmonics, and catalysis.
 M. Davenport, Chemical & Engineering News, 93, 10 (2015) || B.I. Yakobson and R.E. Smalley, American Scientist, 85, 324-337 (1997).
 F. Ding et al. Proc. Natl. Acad. Sci., 106, 2506 (2009) || V. Artyukhov et al. Proc. Natl. Acad. Sci. 109, 15136 (2012) || V. Artyukhov et al. Phys. Rev. Lett. 114, 115502 (2015) || V. Artyukhov - E. Penev, et al. Nature Comm. 5, 489 (2014).
 Z. Zhang et al. Nature Chem. 8, 525 (2016) || Z. Zhang et al. Angewandte Chemie Int. Ed. 54, 13022 (2015) || E. Penev - A. Kutana et al. Nano Lett. 16, 2522 (2016) || Z. Zhang et al. Nano Lett. 6, 6622 (2016) || A. Brotchie, Nature Reviews, doi:10.1038/natrevmats.2016.83 (2016) || S. Shirodkar, Y. Huang et al. (unpublished) || Y. Liu et al. Nature Energy 2, 17127 (2017).
Thursday, September 28, 2017
Speaker: Michael Murray, University of Kansas
Title: There and Back Again: A Journey from classical physics to quantum mechanics and back to classical fields.
Abstract: When the nucleus was discovered it appeared to be a massive classical charged sphere at the heart of atom. Later protons and neutrons were discovered inside the nucleus. Later still it was found that protons and neutrons are themselves made up of quarks held together by gluons. Such objects are described by quantum field theories. As the energy of our colliders has increased we have found more and more gluons inside the nucleus. At some point we expect the gluons to fuse together into a glass like state called the Color Glass Condensate. This new state of quantum matter may actually behave like a classical field.
Thursday, October 5, 2017
Speaker: Chris Adami, Michigan State University
Title: What quantum optics can tell us about black holes
Abstract: Black holes are astrophysical objects whose reality is beyond doubt. However, many aspects of them remain mysterious because observations are difficult and experiments are impossible. Research in the last two decades has revealed a remarkable analogy between the mathematics of quantum black holes and certain quantum optical systems, which makes it possible to study "black hole analogues" in the lab, and to better understand some of the seemingly paradoxical features of black holes. I review recent breakthroughs in black hole physics that were inspired by the quantum optics analogy, and that have removed some of the paradoxes surrounding black holes.
About the speaker: Dr. Adami is Professor for Microbiology and Molecular Genetics & Physics and Astronomy at Michigan State University in East Lansing, Michigan. As a computational biologist, Dr. Adami's main focus is Darwinian evolution, which he studies theoretically, experimentally, and computationally, at different levels of organization (from simple molecules to brains). He has pioneered the application of methods from information theory to the study of evolution, and designed the "Avida"" system that launched the use of digital life (mutating and adapting computer viruses living in a controlled computer environment) as a tool for investigating basic questions in evolutionary biology. He was also a Principal Scientist at the Jet Propulsion Laboratory where he conducted research into the foundations of quantum mechanics and quantum information theory. Dr. Adami earned a BS in physics and mathematics and a Diplom in theoretical physics from the University of Bonn (Germany) and MA and PhD degrees in theoretical nuclear physics from the State University of New York at Stony Brook. He wrote the textbook "Introduction to Artificial Life" (Springer, 1998) and is the recipient of NASA's Exceptional Achievement Medal. He was elected a Fellow of the American Association for the Advancement of Science (AAAS) in 2011.
Thursday, October 12, 2017
Speaker: Pushpa Bhat (FNAL)
Title: Fifty Years of Particle Physics and Discoveries at Fermilab
Abstract: Fermilab, the premier laboratory for elementary particle physics and accelerator research in the U.S., has been at the forefront of fundamental discoveries for the past fifty years. It has had the distinction of discovering three fundamental particles – the bottom and top quarks, and the tau neutrino, as well as leading the detailed exploration of the Standard Model, and making major advances in the pursuit of the Higgs boson. The home of the highest energy proton accelerator and particle collider in the world until the end of the last decade, Fermilab has also led the development of enabling technologies for powerful accelerator facilities. In this talk, I will present the highlights of the past fifty years of particle physics at Fermilab and discuss its future program and role in the new global enterprise of particle physics.
About the speaker: Pushpa Bhat is a senior scientist at Fermi National Accelerator Laboratory (Fermilab), Deputy Head of Fermilab Program Planning, and an Adjunct Professor and graduate faculty at Northern Illinois University. After receiving her Ph.D. in physics from Bangalore University, India, in 1982 and a brief stint as a scientific officer at the Eindhoven University Cyclotron Lab in the Netherlands, she moved to the U.S. and carried out postdoctoral work in experimental high energy physics at Duke University and Fermilab. Her research career has spanned applied physics, nuclear physics and experimental particle physics, from keV energies to the energy frontier. Bhat is a Fellow of the American Physical Society (APS) and the American Association for the Advancement of Science (AAAS). She has served as the Chair of the APS Forum on Physics and Society (FPS) and as Chair of several committees. She currently serves on the APS Council and on the APS Board of Directors, and as Secretary for the International Committee on Future Accelerators (ICFA).
Thursday, October 19, 2017
Speaker: Zhi-Feng Huang, Wayne State University
Title: Exploring microstructures and dynamics of complex systems: Ordering, chirality, defects, and scale coupling
Abstract: One of the long-lasting challenges in the study of advanced materials is how to effectively tackle vast complexity of the system that is of nonequilibrium nature and involves multiple spatial and temporal scales. Of particular importance is the bridging between material microstructural details and mesoscopic characteristics such as surface patterns or interfacial structures, for which much of recent theoretical effort has been put on the development of novel density-field based approaches across different scales. In this talk I will discuss some recent advances in this field for modeling material microstructures and dynamics and some of the ongoing challenges. Sample topics include the emergence of ordering phases, the control of 2D structure or pattern chirality and chiral elastic properties, structures and collective dynamics of topological defects in binary 2D materials such as h-BN, and the interface lattice pinning effect during material growth due to the coupling between micro and meso spatial scales.
Thursday, October 26, 2017
Speaker: Christopher Kelly, Wayne State University
Title: Nanoscale membrane curvature revealed by polarized localization microscopy
Abstract: Many essential biological processes depend on the interaction of lipids, proteins, and carbohydrates at length scales that are unresolvable by conventional optical microscopes. We have combined super-resolution microscopy methods to create polarized localization microscopy (PLM). With PLM, we have measured membrane curvature as small as 20 nm radii, measured curvature-induced molecular sorting, and a local change in the local membrane viscosity. Further, we have discovered that cholera toxin subunit B self-assembles to form nanoscale membrane buds in quasi-one component bilayers to facilitate its immobilization and internalization into cells. We will discuss the physics of PLM and the mechanisms by which cholera toxin bends membranes.
Thursday, November 2, 2017
No Colloquium (Fall Get-Together)
Thursday, November 9, 2017
Speaker: Ken Ritchie, Purdue University
Title: High-speed single molecule tracking of proteins in E. coli
Abstract: All living cells are encapsulated by an outer envelope, which contains a fluid phospholipid-based membrane that structurally delineates the inside of the cell from its environment. Embedded within this membrane is the machinery (proteins) required for the cell to sense and interact with its environment. As such, one expects that there are mechanisms in place to control the location and mobility of the membrane proteins in the fluid membrane in order to perform complex and critical tasks. In this talk, I will present our group's recent single molecule mobility studies into the (dynamic) organization of the cellular membranes of E. coli bacteria performed at acquisition rates up to 1 kHz. Examples will include the structure of the polar region of the inner membrane as seen by the serine chemoreceptor Tsr and investigations into interactions of the iron transporter FepA in the E. coli outer membrane with the inner membrane protein TonB.
About the speaker: Dr. Ritchie is a professor and the Associate Head of Department of Physics and Astronomy at Purdue University. He obtained his PhD at University of British Columbia in Vancouver in 1998, and was the Group Leader in the Kusumi Membrane Organizer Project in Nagoya, Japan in 1998-2005 and an assistant professor at Nagoya University in 2000-2005. He joined Purdue University in 2005 as a professor of physics and is the associate head of the department since 2015.
Thursday, November 16, 2017
No Colloquium -- UG Research Day
Thursday, November 23, 2017
No Colloquium -- Thanksgiving
Thursday, November 30, 2017
Speaker: Jenny Thomas, University College London
Title: An alternative future for neutrino physics
Abstract: Neutrino Oscillations have provided a new insight into the properties of neutrinos since their discovery almost 20 years ago. There are a number of experiments presently providing new results pointing to a future direction in the field. One fundamental and overarching difficulty associated with any kind of measurements of neutrinos is that they only interact with the weak interaction, making their observation rather rare. This leads to very long wait times for results and the need for larger and larger detectors which eventually break the bank. It is time for a paradigm shift in the way neutrino physics is carried out, without the need for 1000 people for each experiment, sums of money that take your breath away and detectors that are so small they need 20 years to make the next fundamental step. I will give an introduction to the physics, the recent results in the field and then talk about an alternative future where we can make measurements quickly with huge detectors at a fraction of the cost of presently planned experiments.
Thursday, December 7, 2017
Speaker: Oleg D. Lavrentovich, Kent State University
Title: Using liquid crystals to command swimming bacteria
Abstract: Self-propelled bacteria are marvels of nature. If we can control their dynamics, we could use it to power dynamic materials and microsystems of the future. Unfortunately, bacterial swimming is mostly random in isotropic liquids such as water and is difficult to control by factors other than transient gradients of nutrients. We propose to command the dynamics of bacteria by replacing water with water-based liquid crystals. The long-range orientational order of the liquid crystal can pre-patterned into various structures by a plasmonic photoalignment technique . The experiments demonstrate that the liquid crystals command the dynamics of bacteria, namely, the trajectories of swimming, polarity of motion, and distribution of bacteria in space . The study of bacteria-liquid crystal system might result in approaches to harness the energy of collective motion for micro-robotic, biomechanical, and sensing devices, as well as micro-mixing and transport of micro-cargo. The work is supported by NSF grants DMR-1507637 and DMS-1729509.
 C. Peng, Y. Guo, T. Turiv, M. Jiang, Q.-H. Wei, O.D. Lavrentovich, Patterning of Lyotropic Chromonic Liquid Crystals by Photoalignment with Photonic Metamasks, Advanced Materials 2017, 1606112 (2017).
 C. Peng, T. Turiv, Y. Guo, Q.-H. Wei, O.D. Lavrentovich, Command of active matter by topological defects and patterns, Science 354, 882 (2016).
About the speaker: Oleg D. Lavrentovich received his Ph.D. (1984) and Doctor of Science (1990) degrees in Physics and Mathematics from the Ukrainian Academy of Sciences for his research on topological defects in liquid crystals. In 1992 he joined the Liquid Crystal Institute at Kent State University. He served as the director of Institute in 2003-2011. He is currently a Trustees research professor affiliated with the Department of Physics, Chemical Physics Interdisciplinary program and the Liquid Crystal Institute at Kent State. His current research focuses on electro-optics of liquid crystals, topological defects, hybrid colloid-liquid crystal systems, liquid crystals as active matter and liquid crystals as nonlinear electrolytes. He is the editor of Liquid Crystals Reviews (Taylor & Francis), associate editor of Soft Matter (Royal Society of Chemistry), Fellow of APS and SPIE.
WSU colloquia from years past may be found here.