Events at Physics |
Events During the Week of September 19th through September 26th, 2010
Monday, September 20th, 2010
- Plasma Physics (Physics/ECE/NE 922) Seminar
- Prospect for Fusion Energy in the 21st Century
- Time: 12:05 pm
- Place: 2535 Engineering Hall
- Speaker: Prof. Farrokh Najmabadi, University of California-San Deigo
- Plasma Theory Seminar
- Numerical Simulation of Non-Inductive Startup in the Pegasus Toroidal Experiment
- Time: 4:00 pm
- Place: 514 ERB
- Speaker: John O'Bryan, UW-Madison Engineering Physics
Tuesday, September 21st, 2010
- Chaos & Complex Systems Seminar
- A New Dynamical Mechanism for Major Climate Shifts
- Time: 12:05 pm
- Place: 4274 Chamberlin Hall
- Speaker: Anastasois Tsonis, UW-Milwaukee Department of Mathematical Sciences
- Abstract: We construct a network of observed climate indices in the period 1900-2000 and investigate their collective behavior. The results indicate that this network synchronized several times in this period. We find that in those cases where the synchronous state was followed by a steady increase in the coupling strength between the indices, the synchronous state was destroyed, after which a new climate state emerged. These shifts are associated with significant changes in global temperature trend and in ENSO variability. The latest such event is known as the great climate shift of the 1970s. We also find the evidence for such type of behavior in three climate simulations using a state-of-the-art model. This is the first time that this mechanism, which appears consistent with the theory of synchronized chaos, is discovered in a physical system of the size and complexity of the climate system.
Wednesday, September 22nd, 2010
- No events scheduled
Thursday, September 23rd, 2010
- R. G. Herb Condensed Matter Seminar
- Raman scattering in graphene: a window on electron dynamics
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Denis Basko, Universite Joseph Fourier & CNRS, Grenoble, France
- Abstract: Graphene, a monolayer of carbon atoms obtained in the laboratory for the first time in 2004, is a very promising material for technological applications. One of the powerful experimental techniques to characterize graphene samples is Raman scattering. The Raman spectrum of graphene consists of several narrow peaks corresponding to emission of one or several phonons. I will discuss theory of Raman scattering in graphene and show that, surprisingly, it carries information not only about phonons, but about the electronic dynamics as well.
- Host: Maxim Vavilov
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- Higgs Boson Distributions from Effective Field Theory
- Time: 4:00 pm - 5:00 pm
- Place: 4274 Chamberlin
- Speaker: Sonny Mantry, University of Wisconsin at Madison
- Host: Michael Ramsey-Musolf
- Graduate Introductory Seminar
- Plasma Seminar
- Time: 5:30 pm - 6:30 pm
- Place: 2223 Chamberlin Hall
- Speaker: Boldyrev, Forest, Sarff, Schnack, Terry, Zweibel
Friday, September 24th, 2010
- Condensed Matter Theory Group Lecture
- Weak chaos in the disordered nonlinear Schroedinger chain: destruction of Anderson localization by Arnold diffusion
- Time: 1:00 pm
- Place: 5310 Chamberlin
- Speaker: Denis Basko, Universite Joseph Fourier & CNRS, Grenoble, France
- Abstract: I will discuss the long-time equilibration dynamics of a strongly disordered one-dimensional chain of coupled weakly anharmonic classical oscillators, which is one of the simplest models allowing to study the effect of a classical nonlinearity on the Anderson localization. The system has chaotic behavior, and it is shown that chaos in this system has a very particular spatial structure: it can be viewed as a dilute gas of chaotic spots. Each chaotic spot corresponds to a stochastic pump which drives the Arnold diffusion of the oscillators surrounding it, thus leading to their relaxation and thermalization. The most important mechanism of relaxation at long distances is provided by random migration of the chaotic spots along the chain, which bears analogy with variable-range hopping of electrons in strongly disordered solids.
- Host: Maxim Vavilov
- Theory/Phenomenology Seminar
- Charmed Mesons -- Their Hadronic Decays and Mixing
- Time: 2:30 pm - 3:30 pm
- Place: 5280 Chamberlin Hall
- Speaker: Chiang-Wei Chiang, National Central University, Taiwan
- Host: Vernon Barger
- Physics Department Colloquium
- Bose Condensation, Superfluidity, and the Quantum Hall Effect
- Time: 4:00 pm
- Place: 2241 Chamberlin Hall (coffee at 3:30 pm)
- Speaker: Jim Eisenstein, Caltech
- Abstract: Composite particles consisting of an even number of fermions(e.g. 4He atoms) can pretend to be bosons. Bosons, of course, can Bose condense and do remarkable things. Superconductivity, which is certainly remarkable when you stop to think about it, result(sort of) from the Bose condensation of electron pairs. With this in mind, theorists have speculated since the early 1960s that excitons (electron-hole pairs in a semiconductor) might be able to do the same thing.
In this talk I will describe experiments done at Caltech on a special collection of excitons that exists in equilibrium and does indeed show many (but not all) of the expected signs of excitonic superfluidity. Surprisingly, the system in question is a double layer two dimensional electron gas. With no valence band holes in sight, where do the excitons come from? - Host: Coppersmith