Events at Physics |
Events During the Week of September 27th through October 4th, 2009
Monday, September 28th, 2009
- Yum Kippur
- Plasma Physics (Physics/ECE/NE 922) Seminar
- Helical Equilibria and Magnetic Structures in Reversed Field Pinch
- Time: 12:05 pm
- Place: 4274 Chamberlin Hall
- Speaker: Maria Ester Puiatti, Conzorio RFX, Italy
Tuesday, September 29th, 2009
- Chaos & Complex Systems Seminar
- Some possible regulatory changes for U.S. financial markets
- Time: 12:05 pm
- Place: 4274 Chamberlin (Refreshments will be served)
- Speaker: Don Hester, UW Department of Economics
- Abstract: This talk is awkward because regulatory change is contentious and legislation about changes is being hotly debated as I organize my comments. Consequently, I will briefly 1) explain why new regulations are needed, 2) propose some reforms that address these needs, and then 3) critically comment on likely legislation.
- Astronomy Colloquium
- Spatially-resolved studies of super star cluster feedback in Starburst Galaxies
- Time: 3:30 pm - 5:00 pm
- Place: 3425 Sterling Hall
- Speaker: Mark Westmoquette, University College - London
- Abstract: Understanding starburst-driven outflows is important for many reasons within the context of galaxy evolution. However, to understand outflows on the large scale, the details of feedback mechanisms from individual star clusters must first be understood. In this talk I will discuss recent results from a number of high spatial and spectral resolution optical integral field spectroscopic studies of the ionized gas environment surrounding super star clusters (SSCs) within nearby starbursts (e.g. NGC 1569, M82, NGC 1140). Through dynamical, excitation and density measurements, these studies are allowing us to build up a picture of (1) how power is fed from these clusters into the surrounding ISM, and (2) how the ISM properties affect how this power is directed.
- Host: Professor John S Gallagher
Wednesday, September 30th, 2009
- No events scheduled
Thursday, October 1st, 2009
- R. G. Herb Condensed Matter Seminar
- Dephasing and disorder effects in quantum spin Hall effect
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Xincheng Xie, Oklahoma State University
- Abstract: The influence of dephasing on the quantum spin Hall effect (QSHE) is studied. In the absence of dephasing, the longitudinal resistance in a QSHE system exhibits the quantum plateaus. We find that these quantum plateaus are robust against the normal dephasing but fragile with the spin dephasing. Thus, these quantum plateaus only survive in mesoscopic samples. Moreover, the longitudinal resistance increases linearly with the sample length but is insensitive to the sample width. These characters are in excellent agreement with the recent experimental results [Science 318, 766 (2007)]. In addition, we define a new spin Hall resistance that also exhibits quantum plateaus. In particular, these plateaus are robust against any type of dephasing and therefore, survive in macroscopic samples and better reflect the topological nature of QSHE.
In addition, we also study the disorder effect on the transport properties in QSHE. We confirm that at a moderate disorder strength, the initially un-quantized two terminal conductance becomes quantized, and the system makes a transition to the novel topological Anderson insulator (TAI). Conductances calculated for the stripe and cylinder samples reveal the topological feature of TAI and supports the idea that the helical edge states may cause the anomalous quantized plateaus. The influence of disorder is studied by calculating the distributions of local currents. Base on the above-mentioned picture, the phenomena induced by disorder in the quantum spin Hall region and TAI region are directly explained. - Host: Robert Joynt
- Introductory Graduate Seminar
- Biophysics
- Time: 5:30 pm
- Place: 2223 Chamberlin Hall
- Speaker: Coppersmith, Gilbert, University of Wisconsin Department of Physics
Friday, October 2nd, 2009
- Special Astronomy Colloquium
- The Wide-Field Infrared Survey Explorer - WISE
- Time: 2:00 pm
- Place: 3425 Sterling Hall
- Speaker: Professor Ned Wright, UCLA- Physics and Astronomy Department
- Abstract:
The Widefield Infrared Survey Explorer (WISE) is a NASA Medium Explorer(MIDEX) currently under construction which will survey the entire sky in 4 mid-infrared bands at 3.4, 4.6, 12 and 22 microns with vastly greater sensitivity than previous all-sky surveys at these wavelengths.
The WISE long wavelength channels will be very powerful for detecting Ultra-Luminous Infrared Galaxies, and WISE should detect the most luminous galaxies in the Universe. The WISE short wavelength channels will be very powerful for detecting old cold brown dwarfs, and WISE should detect the nearest brown dwarfs to the Sun. WISE will also measure the radiometric diameters of about 250,000 asteroids.
WISE will have a 40 cm cryogenic telescope, 1024x1024 arrays, a scan mirror to freeze images on the arrays while the spacecraft scans continuously, and will take 47'x47' images every 11 seconds in all four bands from an IRAS/COBE style Sun-synchronous nearly polar low Earth orbit. WISE is expected to launch in late 2009 - Host: Professor Richard Townsend
- Theory/Phenomenology Seminar
- Theoretical Constraints on the Higgs Effective Couplings
- Time: 2:30 pm
- Place: 5280 Chamberlin Hall
- Speaker: Ian Low, Northwestern University and Argonne National Laboratory
- Host: T. Han
- Physics Department Colloquium
- Search for Time-Reversal-Symmetry-Breaking Effects in Unconventional Superconductors
- Time: 4:00 pm
- Place: 2241 Chamberlin Hall (coffee and cookies at 3:30 pm)
- Speaker: Aharon Kapitulnik, Stanford University
- Abstract: BCS theory of conventional superconductivity can be described by a condensate of Cooper-pairs of time-reversed states. Such superconductors respect time reversal symmetry and are immune against non-magnetic scattering (the Anderson theorem). However, for unconventional superconductors, which do not respect Anderson theorem, there can be a class of superconductors with "chiral" order parameter for which time-reversal symmetry is broken (TRSB). In this talk we will review our recent studies of TRSB in several systems, emphasizing possible triplet superconductors such as Sr2RuO4, the study of the pseudogap state of high temperature superconductors, and the inverse proximity effect in superconductor/ferromagnet bilayer structures.
For a recent review of our studies see: Aharon Kapitulnik, Jing Xia, Elizabeth Schemm and Alexander Palevski, New J. Phys. 11 (2009) 055060. - Host: Chubukov