Colloquium and Seminars
Colloquia
Unless otherwise notified, Colloquia start at 4:45 pm in the Wilder Auditorium (refreshments are in the Physics Library starting at 4:15 pm). Seminars are organized on an individual basis (see seminar link for details). Colloquia organized by Dr. Massimiliano Galeazzi
| 9/9/2009 | Andy Lau, Florida Atlantic University Response and Fluctuations in Active Systems |
| 10/7/2009 | Chris Landsea, NOAA/NWS/National Hurricane Center Hurricane Analysis and Forecasting at the National Hurricane Center |
| 10/28/2009 | Jorge L. Rodriguez, Florida International University Physics at the Large Hadron Collider with the CMS Experiment: Status Fall 2009 |
| 11/4/2009 | Stewart E. Barnes, University of Miami Taking Faraday's law for a spin - gauge theories and spin batteries |
| 12/02/2009 | Roland Romeiser, University of Miami/RSMAS High-resolution ocean current measurements from satellites |
Workshop
| 11/14/2009 Conf. Room 10:30am-3pm |
Mini-Workshop on High-Tc Superconductivity and Related Topics Click for program! |
Seminars
| 10/23/2009 Room 203 3:30pm |
Jonathan D. Armstrong Symmetry breaking and its role in solid state physics |
| 10/30/2009 Room 203 3:30pm |
Narayan Prasai An Introduction to Thermoelectric Power: Significance and Measurement |
| 11/6/2009 Room 203 3:30pm |
Zhisong Tong Introduction to Left-Handed Materials: properties, varieties and my sample |
| 11/13/2009 Room 203 3:30pm |
Shubbendu Nandi The Klein Paradox in Carbon Flatland |
| 11/20/2009 Room 203 3:30pm |
Yu Yue An Introduction to Carbon Nanotubes (structure and application) |
Abstracts
September 9, 2009
Prof. Andy Lau, Florida Atlantic University
Title: Response and Fluctuations in Active Systems
Active complex fluid systems like living cells, assemblies
of motors and filaments, flocks of birds, and vibrated granular
material are nonequilibrium systems that consume and dissipate energy.
These active systems exhibit phenomena that can
be quite distinct from those of conventional equilibrium soft
materials. Nevertheless, their long-wavelength properties can at
times be described by hydrodynamic-like stochastic equations
similar to those of equilibrium systems but with additional
terms that break Onsager reciprocity and noise sources that violate
the fluctuation dissipation theorem. In this talk, we focus on a
model active system, namely, a bacterial bath, which consists of
a population of rod-like motile or self-propelled bacteria
suspended in a fluid environment. We discuss results of recent
microrheological experiments in terms of a dynamical model
for nematic liquid crystals in the isotropic state, appropriately
modified to reflect the activity of bacteria. We show,
in particular, that the non-equilibrium contributions to the stress
arising from the swimming of the bacteria lead to a $1/\sqrt{omega}$
scaling in the power spectrum of the active stress fluctuations,
as observed experimentally.
October 7, 2009
Prof. Chris Landsea, NOAA/NWS/National Hurricane Center
Title: Hurricane Analysis and Forecasting at the
National Hurricane Center
The National Hurricane Center issues
analyses, forecasts, and warnings over large parts of the North
Atlantic and Pacific Oceans, and in support of many nearby countries.
Advances in observational capabilities, operational numerical
weather prediction, and forecaster tools and support systems over
the past 15-20 yr have enabled the center to make more accurate
forecasts, extend forecast lead times, and provide new
products and services. Important limitations, however, persist.
This talk discusses the current workings and state of the nation's
hurricane warning program, and highlights recent improvements and
the enabling science and technology. It concludes with a look
ahead at opportunities to address challenges.
October 28, 2009
Prof. Jorge L. Rodriguez, Florida International University
Title: Physics at the Large Hadron Collider with the CMS Experiment: Status Fall 2009
The Large Hadron Collider (LHC) will resume operations in November of 2009. The LHC is designed to collide protons head on at 7 trillion electron volts and at collision rates higher than ever before achieved in any particle accelerator. The unprecedented energies and the large data rates will usher in a new era of exploration that will allow us to peer further into fundamental constituent of matter and processes that govern our universe. At the LHC experiments are scheduled to search for the origin of mass, the constituents of dark matter and even for the extra-special dimension predicted by string theory. In this talk I will begin by briefly introducing the field of particle physics, highlighting some of these very these basic questions and unresolved mysteries. I will then describe the experimental apparatus constructed globally but gathered at CERN including a short synopsis of the status of the accelerator after its year long hiatus. I will then spend a few minutes describing one of the two large general purpose detectors, the Compact Muon Solenoid experiment, positioned around one of the interaction points and poised to collect data from the LHC.
November 4, 2009
Prof. Stewart E. Barnes, University of Miami
Title: Taking Faraday's law for a spin - gauge theories and spin batteries
Faraday's 1831 law of induction E = - dΦ/dt relates the rate
of change of magnetic flux Φ to the electromotive-force E
produced in a circuit. This accounts only for the forces acting on the
charge of an electron. When the forces acting on the spin are accounted
for this is better stated as
E = - ( hbar / e ) dγ/dt where
γ is the (1984) Berry phase acquired while the electron passes
around a circuit. The Anaronov-Bohm contribution to γ gives back
E = - dΦ/dt while adding the spin Berry phase leads to
a spin-motive-force which in a ferromagnetic material implies
an electromotive-force. Feynman, in 1948, anticipated Berry by showing
the velocity commutation rule [vi,vj ] =
i (e hbar / m2) εijk Bk,
defining the Berry curvature Bk, implies Faraday's law.
A ferromagnetic has broken rotational symmetry and implies a result
for Bk which is a Pauli matrix corresponding a a SU(2)
rather than U(1) gauge group. In turn this leads to the additional
spin terms in Faraday's law. Nearly all generation of electrical
power reflects Faraday's law, while essentially all storage batteries
convert chemical to electrical energy and both lead to currents due
to the forces on the electron's charge. A spin battery converts
energy stored in a magnetic material into electric power via
the extended Faraday's law using the spin-transfer-torque effect
and corresponds to forces acting on the electron's spin. The energy
density stored in such a battery based upon nano-magnets is perhaps
comparable to that of a lead-acid battery. Might this one day
power electric cars?
December 2, 2009
Prof. Roland Romeiser, University of Miami/RSMAS
Title: High-resolution ocean current measurements from satellites
A new remote sensing technique, called along-track interferometric synthetic
aperture radar (along-track InSAR, ATI), permits a direct imaging of line-of-sight
velocity fields from airborne and spaceborne platforms at spatial resolutions better
than 1000 m and swath widths of up to 100 km and more. This capability is attractive
for the observation of moving objects on land as well as for surface current measurements
in coastal waters, rivers, and the open ocean for a variety of applications. A conventional
synthetic aperture radar (SAR) uses coherent processing of signals received by a moving small
antenna to synthesize a long antenna aperture with a high spatial resolution in flight direction.
The along-track InSAR uses two antennas to acquire two images with a short time lag.
Phase differences between the two complex images are proportional to Doppler shifts and
thus to line-of-sight target velocities. This basic concept was first described by
Goldstein & Zebker in (1987); first experiments with airborne ATI systems took place
in the late 1980s and the 1990s. Since then, we have learned how to model the imaging
mechanism of currents and waves theoretically in order to correct measured velocity fields
for contributions of wave motions and imaging artifacts and to study the performance of
spaceborne ATI concepts. A first demonstration of current measurements from space was
possible with data from the Shuttle Radar Topography Mission (SRTM) in
February 2000. The first operational satellite with (experimental) ATI capabilities is
the German TerraSAR-X, which was launched in 2007. The University of Miami's satellite
receiving station, the Center for Southeastern Tropical Advanced Remote Sensing (CSTARS),
will begin to receive TerraSAR-X data in 1010. This presentation gives an overview of basic principles of ATI, the theory of the ATI imaging mechanism of currents and waves, example
results from airborne ATI experiments, SRTM, and TerraSAR-X, and promising applications.
