August 30
Prof. James P. Sethna, Cornell University
Multiscale Manifesto: Physics at the Interfaces between
Continuum, Defect Structures, Defects,and Atoms
People model the properties of materials with a variety
of methods, each appropriate to a certain length scale. Engineers use continuum
mechanics and plasticity to describe the aluminum alloys in their airplanes.
Materials scientists study the evolution
of the polycrystalline grains and particulates making
up the aluminum as it is pounded and rolled into shape. Physicists study
the motion of the atoms (or electrons!) in the aluminum as the stress pushes
a single defect line. Theoretical physicists claim to be experts at deriving
effective theoretical descriptions for exotic phases of matter: why haven't
we had more of an impact on the study of these mundane, structural materials?
I believe we have much to offer, and I'll explain why I think there are
analogies to gauge invariance, Berry's phase, the Meissner/Higgs effect,
and universality. http://www.lassp.cornell.edu/sethna/sethna.html
Note: Prof. Sethna is also speaking at a UIC
International Workshop on Hysteresis and Materials on August 28, and
will be visiting the UIC Physics Department on August 31.
September 6
Dr. Maria Iavarone, Materials Science Division, Argonne
National Laboratory, Argonne Il 60439 and University of Naples "Federico
II", Naples Italy
Probing Superconductivity with a Low Temperature STM
Scanning Tunneling Microscopy is a powerful tool for
exploring surfaces on atomic scale. Both structural and spectroscopic information
can be obtained from the electron tunneling between an atomically sharpened
tip and the sample surface. The study of the superconductivity, both
in the Meissner and in the mixed state, is one of the outstanding application
of the Scanning Tunneling Spectroscopy. We have used low temperature STM
to study both low temperature and high temperature superconductors. The
STM used in the experiments is a home built system operating at 4.2 K in
helium exchange gas. Density of states imaging can reveal the spatial
distribution of magnetic vortices in type II superconductors. This is the
most direct observation of the vortex lattice since the images are obtained
by tunneling into normal and superconducting regions. Beyond to its high
spatial resolution, the decisive advantage of the Scanning Tunneling Spectroscopy,
compared to other techniques, is that for the first time the density of
state inside individual flux line can be probed in real space. I will present
STM observation of vortices on NbSe2 single crystals with random distribution
of topological defect in order to study the effect of the pinning. Deviation
from the conventional hexagonal symmetry have been found in different situations
and can be attributed to various sources. I'll also report on measurements
performed on borocarbide (LuNi2B2C) single crystals which reveal a square
vortex lattice related to the tetragonal crystalline structure of this
material. Moreover the STM allows a direct probe of fundamental properties
of high Tc such as the superconducting gap, the coherence lenght and the
pairing symmetry. Hence STM spectroscopy applied to high Tc materials holds
promise to shed new light on the fundamental nature of high temperature
superconductivity. Results obtained on BSCCO(2212) single crystals and
YNdxBa2-xCu3O7-d will be also discussed.
Host: Helmut Claus
September 13
Dr. Sanford Leuba, National Institutes of Health
Probing Single Chromatin Fibers with AFM and Optical
Tweezers
In the nucleosome ~150 bp DNA are wrapped a couple of
times around an octamer of core histones H3, H4, H2B and H2A, and these
particles are connected by stretches of linker DNA. Nucleosomes are
fundamental particles of eukaryotic chromosomes. Polymerases must
access the underlying DNA template, removing histones in a process involving
force. Using optical tweezers, we have determined the force to unravel
an individual nucleosome in a single chromatin fiber. Investigations
of single chromatin fibers with the atomic force microscope will also be
presented.
Host: Marko
September 20
Prof. E. Lynn Zechiedrich, Baylor College of Medicine
DNA Knotting in Bacteria
We have found that topoisomerase IV unknots DNA in E.
coli and that it does so differently from how it unlinks DNA molecules.
In addition, we have characterized naturally occurring knots in the cell.
Finally, we have shown that knots in DNA kill cells.
Host: Marko
September 27
Prof. Heidi Schellman, Northwestern University
Neutrino Factories
Over the past two years, results from atmospheric neutrinos
and improved studies of solar neutrinos have made a convincing case for
neutrino oscillations with large mixing angles and at least two mass scales.
These measurements indicate, at the minimum, a neutrino sector at least
as rich as the quark sector. Over the next few years several experiments
will be able to get rough estimates of the larger mixing angles by performing
200-700 km baseline experiments at the MeV and GeV scales. However,
several effects, such as the smaller mixing angles, resonant oscillations
due to matter effects, and CP violation are believed to only be accessible
in accelerator based experiments with baselines above 2000 km and beam
energies above 20 GeV. Such beams will require unprecedented fluxes to
give adequate statistics at such distances. I will describe recent
studies of the feasibilty of such experiments.
Host: Varelas
October 4
Prof. Nino Boccara, University of Illinois at Chicago
Highway car traffic as a complex system. The physicist's
point of view.
After a short introduction on complex systems, a few
cellular automaton models of traffic flow will be described. It will be
shown that symmetry breaking field, order parameter, critical phenomena,
variational principle are some of the concepts that help understanding
the behavior of these models.
Host: Aratyn
October 11
Special Colloquium for Graduate Students
Graduate Student Research Opportunities in High-Energy
Particle and Heavy Ion Physics at UIC
1. Professor Russell Betts, UIC - Introduction
2. Professor Cecilia Gerber. UIC - Particle Physics at
UIC
3. Professor David Hofman, UIC - Heavy Ion Physics at
UIC
4. Professor Wai-Yee Keung, UIC - Theoretical Particle
and Heavy Ion Physics at UIC
NOTE: LAS FACULTY MEETING ALSO THIS DAY
October 18
NO COLLOQUIUM - PHYSICS DEPARTMENT FACULTY MEETING
October 25
Prof. Charles L. Kane, University of Pennsylvania
Carbon Nanotubes as Molecular Quantum Wires
The rapid experimental progress in the controlled preparation
of carbon nanotubes bodes well for both applications and fundamental science.
One of the most exciting prospects from the point of view of physics is
that of a nearly ideal quantum wire. In this colloquium we will review
recent developments in our understanding of the electronic properties of
carbon nanotubes. Their purely one dimensional electronic structure leads
to a number of fascinating properties involving scattering, elastic deformations
and electron electron interactions.
Host: Marko
November 1
Dr. Steve Holmes, Fermilab
The Next Generation of High Energy Accelerators
During the twentieth century advances in particle accelerator
technology have fueled the expansion of the energy frontier by nearly six
orders of magnitude. As the latest round of high energy accelerators is
brought into operation it is worth considering what comes next. This talk
will discuss the ultimate performance limitation in high energy particle
accelerators, and the R&D that will need to be completed to continue
into the twenty first century the trends in performance improvement established
during the twentieth.
Host: Varelas
November 8
Prof. Edward W. Kolb, Fermilab & University of
Chicago
Seeds of Cosmic Structure: Quantum Fluctuations in
the Primordial Soup
If the early universe had a phase of rapid expansion
known as inflation, then the pattern of small quantum fluctuations may
be imprinted on the universe in the form of large scale structure and fluctuations
in the background radiation temperature. In the talk I will explain how
something as small as quantum fluctuations can lead to something
as large as a galaxy, and review observational tests of the idea.
Host: Varleas
November 15
Prof. Gerald T. Seidler, University of Washington
Random Close Packing: Fact or Fiction?
The granular bed, or colloquially the sandpile, has become
one of the condensed matter physicist's favorite model systems, exhibiting
geometric frustration, nonlinear response, and self-organization.
In addition to conceptual appeal, the simplest granular beds consisting
of monodisperse hard spheres have relevance for several physical systems,
including powders, liquids, and metallic glasses. Any fundamental
understanding of the transport and mechanical properties of mesoscale disordered
materials (such as sandpiles) must follow from a thorough understanding
of their structure. However, in the overwhelming majority of cases,
experimental characterization of such materials has been limited to first-
and second-order structural correlation functions, i.e. the mean filling
fraction and the structural autocorrelation function. This situation
is especially prevalent in the ongoing sandpile renaissance, wherein experimental
work has largely focused on dynamics while some of the most interesting
theoretical questions concern structure. I will discuss the
combination of synchrotron x-ray microtomography and 3-d image processing
to perform 3-d virtual reconstructions of real sandpiles. We have
used this complete knowledge of structure to compare the relative translational
and bond-orientational order in sandpiles. This characterization
is motivated by hexatic-like theories of glass formation, and provides
new input on the question: "What is random about random close packing?"
Host: Marko
November 22 - NO COLLOQUIUM - Last day before Thanksgiving holiday
November 29 -
Special Colloquium for Graduate Students
Graduate Student Research Opportunities in Condensed
Matter Physics at UIC
1. Professor Nigel Browning, UIC - Interface Physics
2. Professor Juan Carlos Campuzano. UIC - Photoemission
Spectroscopy
3. Professor Richard Kodama, UIC - Magnetic Nanoparticles
4. Professor Sivalingnam Sivananthan, UIC - Microphysics
Lab
December 6 - NO COLLOQUIUM
FINALS WEEK -AND- PHYSICS DEPARTMENT FACULTY MEETING
If you are driving, you can park in any of the public parking lots. Parking Lot 4 at the northwest corner of Halsted and Taylor is most convenient, although occasionally full. Speakers should ask their hosts for a parking validation sticker.
If you are arriving at O'Hare International Airport, you can travel to UIC directly by subway (CTA Blue Line). This costs $1.50, and takes you from inside the airport to the UIC-Halsted CTA Station (at Halsted and Harrison), a few blocks north of the department, in about 50 minutes. Alternatives include taxi (roughly $30 to downtown Chicago), or the Airport Express limosine, which can take you to the Quality Inn at Madison and Halsted (1/2 mile north of campus) for about $15.
If you are arriving at Midway Airport which is southwest of UIC, subway travel is possible (Orange Line to downtown, then change to the Blue Line), but it is much faster to take a taxi ($20).
Map
of UIC East Campus North of Taylor Street (shows Parking Lot 4 and UIC-Halsted
CTA Station)
Map
of UIC East Campus South of Taylor Street (shows SES Building and alternate
public parking)
MapQuestWeb Map of UIC Area
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