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Events During the Week of February 23rd through March 1st, 2020

Monday, February 24th, 2020

Plasma Physics (Physics/ECE/NE 922) Seminar
Frontiers in Linear and Nonlinear Plasma Physics
Time: 12:05 pm - 12:55 pm
Place: 2241 Chamberlin Hall
Speaker: Jeff Parker, Lawrence Livermore National Laboratory
Abstract: This talk will highlight two areas of progress involving linear and nonlinear plasma physics. In the first half I will discuss zonal flows, a pervasive phenomenon in the universe and a prominent example of nonlinear self-organization and pattern formation. The coexistence of zonal flow and turbulence remains incompletely understood, as coherent zonal structures spontaneously break the oft-assumed symmetries of homogeneity and isotropy and profoundly alter the character of turbulent flow. Moreover, intense practical interest in zonal flows has arisen because they are believed to regulate the deleterious turbulence that degrades confinement in magnetic fusion devices. A recent statistical approach has led to breakthroughs in the theoretical understanding of zonal flow, with a systematic framework offering an analytically tractable, self-consistent model that captures many features of zonal flow behavior. Plasma physics also offers insight into zonal flow in gas giants, as considerations from MHD may explain recent measurements of the zonal-flow termination depth of 3,000 km in Jupiter.

In the second half, I will discuss how even linear physics can surprise us with new and rich phenomena. Topological phases of matter were recognized by the 2016 Nobel Prize and are now a large subject in condensed matter physics and photonics. I will present the first applications of these ideas to plasma physics with two examples: (1) A topological gaseous plasmon polariton at the surface between a magnetized plasma and vacuum, and (2) the Reversed-Shear Alfvén Eigenmode, well known in tokamaks. The new field of topological plasma waves represents a multifaceted research frontier with fundamental questions to be addressed by theory, simulation, and experiment.
Host: Jan Egedal
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Atomic Physics Seminar
QC Cluster Seminar
tbd
Time: 3:00 pm - 4:00 pm
Place: 5310 Chamberlin Hall
Speaker: Erhan Saglamyurek, University of Alberta
Abstract: tbd
Host: Mark Saffman
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Tuesday, February 25th, 2020

Chaos & Complex Systems Seminar
The emergence of human emotions: Learning, development and biology
Time: 12:05 pm - 1:00 pm
Place: 4274 Chamberlin (refreshments will be served)
Speaker: Seth Pollak, UW Department of Psychology
Abstract: Theories about the emergence of human emotion have traditionally emphasized evolutionarily preserved, universal aspects of emotion or the functional and cultural adaptations of emotions. While these opposing views make different assumptions about the initial state of emotion in the brain, both theories devote little attention to or specification about potential processes for learning and developmental change. This colloquium will focus on the question of how brain and behavior are shaped and refined by children's early social and emotional experiences. To do so, I will describe recent research involving children who have experienced aberrant early life experiences. These include child abuse and neglect, children raised in extreme poverty, children raised in institutional settings, and children who have endured traumatic life experiences. Studies of these children provide new insights about the developmental processes underlying socio-emotional learning as well as shed light on the mechanisms through which children acquire emotions. In addition to these basic science questions, children raised in adverse environments are at increased risk for a variety of health, academic, and social problems. I will highlight ways in which research in this area can both address central issues in human development as well as hold tremendous promise for improving the health and well-being of children.
Host: Clint Sprott
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NPAC (Nuclear/Particle/Astro/Cosmo) Forum
Neutrino Oscillations at the End of the World
Time: 3:00 pm
Place: 4274 Chamberlin Hall
Speaker: Summer Blot, DESY
Abstract: The IceCube Neutrino Observatory is a pioneering, cubic kilometre-sized neutrino telescope located at the geographic South Pole. Since its discovery of the astrophysical neutrino flux, IceCube has continued to provide invaluable knowledge about both neutrino sources and neutrino properties at the GeV-PeV scale through its detection of neutrino interactions via Cherenkov radiation in the optically clear, deep glacial ice. In this talk I will focus on the most recent measurements of atmospheric neutrino oscillations with the IceCube DeepCore sub-array. Recent improvements in detector calibration and modelling of systematic uncertainties have paved the way for new measurements with unprecedented sensitivity above 5 GeV. I will also describe our progress on a near-future detector extension, the IceCube Upgrade, which will deploy new optical modules into the ice along with improved calibration devices to further enhance the performance of the IceCube Neutrino Observatory.
Host: Albrecht Karle
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Council Meeting
Time: 4:00 pm - 5:00 pm
Place: 2314 Chamberlin Hall
Host: Sridhara Dasu
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Wednesday, February 26th, 2020

Department Meeting
Time: 12:15 pm - 1:15 pm
Place: B343 Sterling Hall
Speaker: Sridhara Dasu, Department Chair
Host: Sridhara Dasu
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Theory Seminar (High Energy/Cosmology)
Cosmology with cosmic voids
Time: 4:00 pm
Place: 5280 Chamberlin
Speaker: Alice Pisani, Princeton
Abstract: Modern surveys provide access to high quality measurements on large areas in the sky and span large redshift ranges—thus sampling the galaxy distribution in detail also in the emptier regions, voids. Void cosmology is becoming an increasingly active sector of galaxy clustering analysis: by measuring void properties, such as the void size function or density profiles, it is possible to constrain cosmological parameters. Voids are particularly sensitive to the properties of dark energy and are a powerful tool to test modifications of the laws of General Relativity. In this talk I illustrate the use of cosmic voids as a tool for cosmology, I present recent developments in the field and discuss the constraining power of voids to be observed by upcoming surveys.
Host: Dan Chung
Presentation: Seminar_UWM_AlicePisani.pdf
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Thursday, February 27th, 2020

R. G. Herb Condensed Matter Seminar
The Complex Mesoscale Dynamics of Condensed Matter Systems Unveiled by High-resolution Inelastic X-Ray Scattering
Time: 10:00 am
Place: 5310 Chamberlin Hall
Speaker: Alessandro Cunsolo, Brookhaven National Laboratory
Abstract: Since the end of the past millennium, high-resolution Inelastic X-Ray Scattering (IXS) has substantially improved our knowledge of the collective molecular dynamics of disordered systems. This technique enabled us to explore a host of phenomena occurring over distance and time windows respectively approaching nearest neighbor atomic separations and ‘in cage’ oscillation periods. It elucidated fundamental aspects of the high-frequency transport properties of fluids, such as the persistence of extended hydrodynamic excitations beyond the continuous limit, the microscopic mechanism driving relaxation phenomena, and the onset of quantum effects. In more recent years, an increasing number of IXS investigations have been focusing on more complex mesoscale structures promising new functionalities; the outcome of these studies could inspire new routes to manipulate the high-frequency acoustic propagation in materials. Finally, technical improvements of IXS and other synchrotron-based methods could soon enable a whole new class of investigations of transient phenomena in metastable states or undergoing a phase transition.
Host: Gilbert
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Cosmology Journal Club
Time: 12:00 pm - 1:00 pm
Place: 5242 Chamberlin Hall
Abstract: We discuss papers from arxiv.org related to cosmology each week. All are welcome and feel free to bring your lunch. If there is a paper you would like to present, or have questions or comments, please email Ross Cawthon (cawthon@wisc.edu) and Santanu Das (sdas33@wisc.edu).
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Astronomy Colloquium
The Life Cycle of galaxies in clusters over 10 Billion Years
Time: 3:30 pm - 5:00 pm
Place: 4421 Sterling Hall, Coffee and cookies 3:30 PM, Talk begins 3:45 PM
Speaker: Greg Rudnick, Director of Graduate Studies, University of Kansas, Department of Physics and Astronomy
Abstract: Galaxies live in a range of environments, characterized by their volume density. For example, the densest regions of the Universe are in galaxy clusters, which contain hundreds to thousands of galaxies all in pseudo gravitational virial equilibrium. These dense environments can in turn alter the properties of the galaxies themselves in striking ways via a variety of gravitational and hydrodynamic processes. The result of these processes alter galaxy shapes, their internal dynamics, and shuts off the formation of new stars. I will present work I have been doing to characterize the evolution of galaxies in clusters over the past 10 billion years as a way of understanding how the environment can affect galaxies. I will describe how we have used extensive multi-wavelength data sets on distant clusters to form a picture in which infalling cluster galaxies likely have their gas supplies cut off, their morphologies transformed, and may even experience epochs of very frequent mergers. I will then describe new results from a large program called Gemini Observations of Galaxies in Rich Environments (GOGREEN) which is the premier spectroscopic survey of distant clusters. With the GOGREEN data, we are finding that the quenching of galaxies in dense environments at high redshift may proceed very differently from that at redshifts less than one, requiring a revision of our thoughts on how environment affects galaxy evolution at large lookback times.
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Friday, February 28th, 2020

PhD Prospective Student Visit Day
Time: 1:30 pm - 5:00 pm
Speaker: na, na
Abstract: For admitted students only
Host: Michelle Holland, Graduate Program Coordinator
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Physics Department Colloquium
Multi-messenger Astrophysics: Probing Compact Objects with Cosmic Particles
Time: 3:30 pm
Place: 2241 Chamberlin Hall
Speaker: Ke Fang, Stanford University
Abstract: The study of compact stellar remnants such as black holes and neutron stars is an important component of modern astrophysics. Recent observations of the first neutron star merger event and an active galactic nucleus as the first high-energy neutrino source open a new way to study compact objects using multi-messengers. The key to coordinated detection and interpretation of multiple messenger signals, namely, electromagnetic radiation, cosmic rays, neutrinos, and gravitational waves, is to understand the link between the messengers. We try to answer this question from both theoretical and observational perspectives. We study high-energy particle propagation in the vicinity of magnetar-powered transients and black hole jets using numerical simulation. We also investigate analysis frameworks aiming to exploit data across multiple wavelengths and messengers. We close the talk by overlooking the future of Multi-messenger Astrophysics, in light of upcoming facilities such as SWGO and LSST, as well as new questions brought by recent observations.
Host: Albrecht Karle
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