Events at Physics |
Events During the Week of September 28th through October 5th, 2008
Monday, September 29th, 2008
- Plasma Physics (Physics/ECE/NE 922) Seminar
- Plasma Rotation Driven by Static Non-axisymmetric Magnetic Fields in DIII-D
- Time: 12:05 pm
- Place: 1227 Engineering Hall
- Speaker: Dr. Andrea Garofalo, General Atomics
- Special Astronomy Colloquium Talk
- Molecular Clouds and Star Formation in the Magellanic Clouds
- Time: 3:30 pm
- Place: 3425 Sterling Hall
- Speaker: Dr. Yasuo Fukui, Nagoya University, JAPAN
- Abstract: I will present the molecular image of the Magellanic Clouds obtained with NANTEN 4m telescope and other telescopes at mm/sub-mm wavelengths and discuss molecular cloud properties and star formation. The Magellanic Clouds are ideal nearby galaxies where we are able to have a comprehensive and uniform sample of star formatting regions. Previous studies with NANTEN revealed that the molecular clouds are classified into three types, Type I no O star formation, Type II limited O star formation and Type III most active cluster formation, and that the total lifetime of a giant molecular clouds are ~30Myrs. Recent sub-mm data allow us to reveal dense clumps within these molecular clouds and tell us how gas condense to form clusters. The Spitzer SAGE program offers a sample of less luminous young stars associated with the molecular clouds. We also learn how lower density HI gas is accumulating onto the molecular clouds by making a 3-dim comparison between CO and HI. I will use these results to make a comprehensive view of star formation in a galaxy.
http://ads.nao.ac.jp/abs/2008arXiv0804.1458F
http://ads.nao.ac.jp/abs/2008arXiv0804.1458F
http://ads.nao.ac.jp/abs/2007prpl.conf...81B
http://ads.nao.ac.jp/abs/2007prpl.conf...81B
- Host: Professor Snezana Stanimirovic
- High Energy Seminar
- Observation of the Ground State of the bbbar System
- Time: 4:00 pm
- Place: 4274 Chamberlin (Coffee and Cookies at 3:45 pm)
- Speaker: Veronique Ziegler, SLAC
- Host: Matt Herndon
- Plasma Theory Seminar
- Low Collisionality Neoclassical Toroidal Viscosity in Tokamaks and Quasi-symmetric Stellarators
- Time: 4:00 pm
- Place: 514 ERB
- Speaker: Andrew Cole, UW-Madison, Dept. of ECE
Tuesday, September 30th, 2008
- Chaos & Complex Systems Seminar
- Indicators of regime shifts in ecosystems
- Time: 12:05 pm
- Place: 4274 Chamberlin (Refreshments will be served)
- Speaker: Steve Carpenter, UW Center for Limnology
- Abstract: Ecosystems occasionally undergo rapid massive changes - desertification, algae blooms of lakes, replacement of coral reefs by fleshy algae turf, trophic cascades, economic collapse of fisheries, and shrub invasion of rangelands are a few examples. Some regime shifts have big impacts on human life-support and are therefore important for environmental policy. Thus the detection and prediction of regime shifts has emerged as a research topic in basic and applied ecology. Theory shows that certain regular changes in time series should be measurable before an incipient regime shift - autoregression coefficients near one, variance spectra shifted to low frequencies, and rising variance, skewness and kurtosis, for example. However, not all regime shifts show these indicators, and some show opposite responses. While leading indicators show promise as tools for field science and ecosystem management, at present it is difficult to diagnose the characteristics of incipient regime shifts from the indicators alone. Field trials, and modeling to connect theory with the characteristics of particular ecosystems in the field, are needed to improve our understanding of these signals.
- Astronomy Colloquium
- The Assembly of Galaxy Disks and Evolution of Galactic Structures in COSMOS - Reconstructing the Hubble Sequence
- Time: 3:30 pm
- Place: 6515 Sterling Hall
- Speaker: Kartik Sheth, CALTECH
- Abstract: We have analyzed the redshift-dependent fraction of galactic bars over 0.2<z<0.84 in 2,157 luminous face-on spiral galaxies from the COSMOS2-square degree field. Our sample is an order of magnitude larger than that used in any previous investigation, and is based on substantially deeper imaging data than that available from earlier wide-area studies of high-redshift galaxy morphology. We find that the fraction of barred spirals declines rapidly with redshift. Whereas in the local Universe about 65% of luminous spiral galaxies contain bars (SB+SAB), at z~0.84 this fraction drops to about 20%. Over this redshift range the fraction of strong (SB) bars drops from about 30% to under 10%. It is clear that when the Universe was half its present age, the census of galaxies on the Hubble sequence was fundamentally different from that of the present day. A major clue to understanding this phenomenon has also emerged from our analysis, which shows that the bar fraction in spiral galaxies is a strong function of stellar mass, integrated color and bulge prominence. The bar fraction in very massive, luminous spirals is about constant out to z~0.84 whereas for the low mass, blue spirals it declines significantly with redshift beyond z=0.3. There is also a slight preference for bars in bulge dominated systems at high redshifts which may be an important clue towards the co-evolution of bars, bulges and black holes. Our results thus have important ramifications for the processes responsible for galactic downsizing, suggesting that massive galaxies matured early in a dynamical sense, and not just as a result of the regulation of their star formation rate. <br>
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- Host: Professor Eric Wilcots
Wednesday, October 1st, 2008
- Find Our People Meeting
- Potential Physics & Related Majors
- Time: 4:00 pm
- Place: 2241 Chamberlin Hall (Coffee, tea, cookies will be served starting at 3:30)
- Abstract: You are invited to our annual "Find Our People Meeting" in which undergraduate majors and potential majors are invited to come meet, listen to, chat with, and query the people involved in the department's undergrad program and activities. Copies of the 2008 edition of the "Physics Majors Handbook" will be distributed and potential majors, names and e-mail addresses will be solicited for the distribution lists maintained in the department office and by the Physics Club.
People whom we hope to have present for the students to meet include officers of the Physics Club and other upper division majors with information to share, the club advisor, the mentor assignment committee, the undergrad advisors, including the AMEP and honors advisor, the instructors of the undergraduate courses, the undergraduate secretary, the personnel officer, the academic department manager, the undergraduate coordinator, the chair and associate chair, and others actively involved with undergraduates, particularly those who tend to employ them or like to answer the question, "Why should I seriously consider being a Physics Major?' - Host: Physics Department
Thursday, October 2nd, 2008
- R. G. Herb Condensed Matter Seminar
- Quantum transport and its classical limit
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Piet Brouwer, Cornell University
- Abstract: The interference of multiply scattered quantum mechanical matter waves causes small but noticeable corrections to the electrical conduction of a metal at low temperatures. What is the fate of quantum interference corrections in the limit that the wavelength of the electrons becomes small in comparison to all other relevant length scales? This limit is a "classical limit" similar to the transition from wave optics to ray optics that occurs when the typical size of optical elements becomes much larger than the wavelength of light. Surprisingly, the answer is not at all trivial: Whereas the interference correction to the ensemble-averaged conductance (weak localization) disappears in this classical limit, the quantum interference contribution to the sample-specific conductance fluctuations survives.
The "classical limit" is relevant for conductors in which the electron motion is ballistic and the only source of scattering is specular reflection off sample boundaries or artificial macroscopic scattering sites. In this talk, I'll outline the basic structure of a theory of quantum transport in ballistic conductors, as well as possible experimental signatures that distinguish ballistic conductors and their disordered counterparts.
- Host: Vavilov
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- LSST, the most complete survey of the sky: How tools of particle physics can serve in astronomy
- Time: 4:00 pm
- Place: 4274 Chamberlin
- Speaker: Michael Prouza, FZU Prague, Czech Republic
- Abstract: For a few decades it is clear that astronomy and particle physics share a number of interesting topics. The Large Synoptic Survey Telescope (LSST) is one of the newest proofs that these two significantly different communities can also effectively cooperate within one project. Construction of the unique 8.4-meter LSST telescope started earlier this year. The telescope will be equipped with a huge 3.2 Gigapixel camera and will have a field of view of 10 square degrees. During single 15-second exposures it will capture stars up to 25th magnitude, and the whole accessible sky will be covered every three nights. During 10 years of operation, the LSST will create a "movie of the deep space" - each spot on the sky will be imaged at least 300 times. After its completion in 2014, the LSST will be the most advanced surface tool for the mapping of dark energy and dark matter, and the most sensitive instrument for detection and identification of any transient sources. Thus, the LSST will e.g. collect an unprecedented number of supernovae and will identify the trajectories of most of the so-called Earth Threatening Asteroids. In my talk I will discuss the current status, the technical challenges, and the potential scientific impacts of the LSST project.
- Host: Stefan Westerhoff
Friday, October 3rd, 2008
- Theory/Phenomenology Seminar
- The Simplicity of Scattering Amplitudes
- Time: 1:30 pm
- Place: 5280 Chamberlin Hall
- Speaker: Ruth Britto, Fermilab
- Host: Frank Petriello
- Physics Department Colloquium
- Cosmic Rays
- Time: 4:00 pm
- Place: 2241 Chamberlin Hall (coffee at 3:30 pm)
- Speaker: Pierre Sokolsky, University of Utah
- Abstract: The fourty year search for the end of the cosmic ray spectrum, the so-called Greisen-Zatsepin-Kuzmin (GZK) Cutoff is described. This is the result of the inelastic interactions between ultra-high energy cosmic rays and the remnant universal black-body radiation. The first definitive observation of this effect has recently been published by the High Resolution Fly's Eye Experiment. This result and confirming evidence from the Pierre Auger Experiment will also be presented and discussed. Results on the ultra-high energy composition and anisotropy will also be presented as well as a discussion of the new Telescope Array project.
- Host: Halzen