Events at Physics |
Events During the Week of October 23rd through October 30th, 2011
Monday, October 24th, 2011
- Plasma Physics (Physics/ECE/NE 922) Seminar
- The Solar-Wind Plasma
- Time: 12:05 pm
- Place: 2317 Engineering Hall
- Speaker: Joe Borovski, LANL
- Condensed Matter Theory Group Seminar
- Theory of Anderson localization III: diagrammatic approach and experiment
- Time: 4:30 pm
- Place: 5310 Chamberlin
- Speaker: Peter Wölfle, Karlsruhe Institute of Technology, Germany
- Abstract: A self-consistent equation for the diffusion coefficient is reviewed and interpreted. The results obtained account very well for the diffusion coefficient not too close to criticality. A recent generalization of the theory to open finite size systems is applied to experiments on localization of acoustic waves, with good success. Recent experiments on the localization of ultracold atoms by a random potential are considered. Dynamic localization and the Anderson transition in the kicked rotor model is reviewed.
- Host: Perkins
Tuesday, October 25th, 2011
- Chaos & Complex Systems Seminar
- Airway sensory deficits in Parkinson’s Disease – Evidence of a complex system gone awry? Now what?
- Time: 12:05 pm
- Place: 4274 Chamberlin
- Speaker: Michael J. Hammer, UW School of Medicine and Public Health
- Abstract: Historically, Parkinson's Disease (PD) has simply been classified as a "movement disorder". Recent evidence, including data from our laboratory, strongly suggests a more complex model of sensory-movement interaction whereby airway movements are guided by sensory (e.g., touch) inputs to the central nervous system. Sensory-movement interactions, and the related deficits that accompany PD, substantially impact a constellation of important airway functions such as breathing, cough, speech, swallow, and voice. This seminar will focus on (a) how airway sensory-movement functions are negatively impacted by PD, (b) the clinical consequences of this impact, and (c) strategies that may improve these airway sensory-movement functions in PD.
- Host: Sprott
- Whitford Lecture
- "The Restless Universe (Palomar Transient Factory)
- Time: 3:30 pm - 5:00 pm
- Place: 4421
- Speaker: Shrinivas Kulkarni, CALTECH
- Abstract: Cosmic explosions were first noted nearly two thousand years ago.However, secure recognition and study began only a hundred years ago. What was once termed as Stella Nova (new stars) are now divided into two major families, novae and supernovae (with real distinct classes in each). Equally the variable stars have a rich phenomenology. Together, supernovae and variable stars have contributed richly to key problems in modern astrophysics: distances to galaxies, cosmography and build up of elements in the Universe.<br>
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The Palomar Transient Factory (PTF), an innovative 2-telescope system, was designed to explicitly to chart the transient sky with a particular focus on events which lie in the nova-supernova gap. PTF is now finding an extragalactic transient every 20 minutes and a Galactic (strong) variable every 10 minutes. Extensive spectroscopy and photometry allowed us: to identify an emerging class of ultra-luminous supernovae, discover luminous red novae, undertake UV spectroscopy of Ia supernovae, discover low budget supernovae, clarify sub-classes of core collapse and thermo-nuclear explosions, map the systematics of core collapse supernovae, identify a trove of eclipsing binaries and the curious AM CVns.<br>
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Wednesday, October 26th, 2011
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- GRB Observations with Fermi Large Area Telescope
- Time: 2:30 pm
- Place: 4274 Chamberlin Hall
- Speaker: Vlasios Vasileiou, LUPM, Universite de Montpellier, Montpellier, France
- Abstract: During its first three years of operations, since August 2008, the Large Area Telescope on board the Fermi spacecraft (Fermi-LAT) has detected more than 30 GRBs in the ~30 MeV - 300 GeV energy range, and has set upper limits on the E>100 MeV emission on hundreds of GRBs occurring in its field of view. These results revealed new and puzzling features in the temporal and spectral behavior of GRBs, such as a delayed onset of the high-energy (E>100 MeV) emission with respect to the lower-energy (keV/MeV) signal detected by the Gamma-Ray Burst Monitor (Fermi-GBM), the presence of an extra spectral component in addition to the Band function, an extended emission lasting significantly longer than the lower-energy keV/MeV prompt emission, and the presence of spectral cutoffs at tens-of-MeV energies. We will present these discoveries and their theoretical implications, focusing both on individual cases and also in the context of a systematic and unbiased study performed towards the first Fermi-LAT GRB catalog. In addition, constraints on any energy dependence of the speed of light placed with GRB observations will be presented.
- Host: Segev BenZvi
- Astronomy Colloquium
- Spectroscopic Support of Southern Photometric Surveys
- Time: 3:30 pm - 5:00 pm
- Place: 4421 Sterling Hall
- Speaker: Mario Mateo, University of Michigan
- Abstract: he upcoming large-scale photometric surveys of the Southern Sky (SkyMapper, PanSTARRS, LSST, GAIA) promise to produce vast catalogs of interesting targets relevant to just about every area of modern astrophysics. I will describe a conceptual plan for a dedicated, all-sky spectroscopic survey that would powerfully complement these photometric projects. The focus of this plan is to develop a facility - the Southern Spectroscopic Survey Telescope (SSST) - that will provide highly flexible, wide-field and moderately deep spectroscopic capabilities over the entire Southern sky. The SSST's capabilities - all based on well-understood, proven technologies - allow it to efficiently explore a wide range of science projects. In particular, the SSST's ability to carry out a range of spectroscopic surveys simultaneously - each of which may involve targets with diverse field distributions and which require vastly different wavelength coverage and spectral resolution - will make it a uniquely powerful facility to advance a broad range of astronomical disciplines. I will describe how the science case for the SSST might be developed and implemented using, as preliminary examples, some specific science cases of interest to astronomers at the University of Michigan. I will also outline an approach that we have begun to pursue that aims to build a viable consortium -perhaps one spearheaded by the institutions of the Big-10? - that could build and operate the SSST through its initial survey cycles.
- Host: Professor Matt Bershady
Thursday, October 27th, 2011
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- COSMIC RAY ACCELERATION IN SUPERNOVA REMNANTS
- Time: 4:30 pm
- Place: 4274 Chamberlin
- Speaker: Pasquale Blasi, Osservatorio Astrofisico di Arcetri (Florence, Italy)
- Abstract: Present observations, especially in the gamma ray band, appear to confirm the need for source spectra of cosmic rays steeper than suggested by current theories. This trend is also required by observations of the anisotropy on large scales which in the TeV range is at the level of $sim 10^{-3}$ and appear to stay roughly constant with energy up to around the knee region. Steep spectra are very difficult to explain unless one invokes poorly understood effects in particle scattering or probably the presence of neutrals in the medium where the shock propagates. I will discuss these issues with particular emphasis on the process of particle acceleration in partially ionized media.
- Host: Paolo Desiati
- Graduate Introductory Seminar
- Biophysics Seminar
- Time: 5:30 pm
- Place: 2223 Chamberlin Hall
- Speaker: Coppersmith, Gilbert
Friday, October 28th, 2011
- Cosmology Journal Club
- An Informal discussion about a broad variety of arXiv papers related to Cosmology
- Time: 12:00 pm
- Place: 5242 Chamberlin Hall
- Abstract: Please visit the following link for more details:
http://cmb.physics.wisc.edu/journal/index.html
Please feel free to bring your lunch!
If you have questions or comments about this journal club, would like to propose a topic or volunteer to introduce a paper, please email Le Zhang (lzhang263@wisc.edu) - Host: Peter Timbie
- Theory Seminar (High Energy/Cosmology)
- Phenomenology of a pseudoscalar inflaton: naturally large non-gaussianity
- Time: 2:00 pm
- Place: Chamberlin 5280
- Speaker: Marco Peloso, University of Minnesota
- Abstract: More than 20 years ago, it has been noted that pseudoscalar axions are one of the best candidates for the inflaton field, since the flatness of their potential is protected against radiative corrections by a shift symmetry. Axions have a specific coupling to gauge fields; however, such coupling has so far received little attention in connection to inflation. We show that this coupling can actually drastically change the phenomenological predictions of the most straightforward realizations of axion inflation. The signatures in the CMB anisotropies are highly distinctive and promising: a specific and large non-gaussianity of (nearly) equilateral shape, in addition to detectably large spectral tilt and gravity waves. The same coupling can also lead to observable gravitational waves at interferometers as Advanced LIGO/VIRGO. The current bounds on non-gaussianity imply that the coupling of a pseudo-scalar inflaton to any gauge field must be smaller than about 1/10^{16} GeV; this limit is about 5 orders of magnitude stronger than the analogous limit for the coupling of the QCD axion to photons.
- Physics Department Colloquium
- Nature Adorns a Vacuum: The Casimir Force
- Time: 3:30 pm
- Place: 2241 Chamberlin Hall (coffee at 4:30 pm)
- Speaker: Steve Lamoreaux, Yale University
- Abstract: In 1948, Hendrik Casimir showed that two perfectly conducting parallel plates will be mutually attracted. This attraction is due to the modification of the the electromagnetic field mode structure between the plates, which leads to a change in the zero point energy of the field. It has only been within the last 15 years that this force has been measured to good precision, and recently the effect of finite temperature (300 K) has been measured, for the first time, in our laboratory at Yale. The notion that boundaries can affect the zero point energy of a system has broad application throughout physics, and some applications will be discussed, along with an overview of our experimental work.
- Host: Heeger