Physics Colloquia - 2008

(Tea and Cookies at 2:45pm)

Friday, 25 January 2008, 3:00pm

Professor Benjamin Bromley, University of Utah, Dept. of Physics
The Formation of Planets Like the Earth
Location: Physics 135

A spectacular merger of physics, astronomy and biology would be the detection of life beyond our own solar system. The formation of planets capable of bearing life is a high priority for our effort to understand the universe we live in, and its details are becoming increasingly understood. However, the dynamics of building up a "terrestrial" planet in the habitable zone around a star are complicated and require the use of supercomputers for modeling. Yet even with the best of our computational abilities, questions remain: how quickly did a terrestrial planet form? What was the consequence of the formation of high-mass -- and mobile -- Jupiter-size planets as they influence the orbits of life-bearing planets? In our own solar system, the answer is clear, but in systems where the "Jupters" move from their original position to locations within the habitable zone, what happens to the terrestrial planets? In this talk, we will review terrestrial planet formation and address these outstanding issues.

Friday, 1 February 2008, 3:00pm

Stefan Westerhoff, University of Wisconsin-Madison
New Results from the Pierre Auger Observatory
Location: Physics 135

The Pierre Auger Observatory in Malargue, Argentina, is the world's largest detector for the study of the origin of ultrahigh energy cosmic rays. The experiment stretches over 3000 km2 and measures cosmic rays with energies above 1018 eV using two complementary detector types: an array of 1600 particle detectors on the ground, and 4 fluorescence detectors overlooking the ground array from the periphery. The Observatory is now nearing completion, but scientific data taking started at the beginning of 2004. The analysis of the data shows first indications that the arrival direction distribution of the highest energy cosmic rays is not isotropic, but might be associated with the positions of nearby extragalactic objects. In this talk, I will review recent results from the first few years of data taking, with a special emphasis on the arrival direction of the highest energy cosmic rays and their possible correlation with known astrophysical sources.

Friday, 8 February 2008, 3:00pm

Select Faculty Members, UW-Milwaukee, Dept. of Physics
Overviews of Individual Research
Location: Physics 135

UWM Physics faculty members Daniel Agterberg, John Friedman, Marija Gajdardziska-Josifovska, Carol Hirschmugl, Lian Li and Paul Lyman, will present short (15-minute) overviews of their particular research and current work in the Physics Dept.

Friday, 15 February 2008, 3:00pm

Cancelled -- tentatively rescheduled for 3-21-08
Location: Physics 135

Friday, 22 February 2008, 3:00pm

Andrew Kunz, Assistant Professor, Dept. of Physics, Marquette University
Field-driven domain wall dynamics in magnetic nanowires
Location: Physics 135

Moving domain walls in magnetic nanowires have been proposed for use in a variety of technological applications including storage, logic, and sensing. The viability of these devices is dependent on the speed, control, and reliability of the moving walls. Micromagnetic simulation is a useful tool to explore the dynamics of domain-wall motion in a variety of wire geometries. I will present our results which demonstrate new techniques to increase domain wall speed, increase the range of reliable domain wall motion, and quickly inject domain walls into the wires. Simple physical models will be presented to explain the results.

Friday, 29 February 2008, 3:00pm

Select Faculty Members, UW-Milwaukee, Dept. of Physics
Overviews of Individual Research
Location: Physics 135

UWM Physics faculty members Prasenjit Guptasarma, Abbas Ourmazd, Sarah Patch, Valerica Raicu, Dilano Saldin, and Alan Wiseman, will present short (15-minute) overviews of their particular research and current work in the Physics Dept.

Friday, 7 March 2008, 3:00pm

Dr. Keith Moffat, Louis Block, Professor of Biochemistry and Molecular Biology , Institute for Biophysical Dynamics, University of Chicago
How Do Biological Macromolecules Respond to Light? (Studies by Static and Time-resolved Crystallography)
Location: Physics 135

Special Introduction: We are delighted to welcome Dr. Keith Moffat, a pioneer and world renowned researcher in protein crystallography, to UW-Milwaukee, as part of the Physics colloquia! Currently the Louis Block Professor of Biochemistry and Molecular Biology at the Institute for Biophysical Dynamics of the University of Chicago and the principal investigator at the Center for Advanced Radiation Sources (CARS), Moffat and his team have developed synchrotron X-ray beam lines suitable for many experiments in structural biology at the Advanced Photon Sources (APS) at Argonne National Laboratory. Using crystallographic methods, his research is aimed at the identification of the ways in which biological molecules respond to light. In addition, the effects of crystal freezing and radiation damage on data quality from macromolecular crystals are active areas of research in Dr. Moffat's lab. Dr. Moffat received his PhD with Max Perutz (Nobel Laureate for the structure of hemoglobin) in Cambridge, and has also worked with Quentin Gibson (who pioneered transient state kinetics in bio-molecules), in the US. One of many highlights from his illustrious career, Dr. Moffat has pioneered time-resolved crystallography over a time-period of more than 25 years after x-ray sources with sufficient intensity became available in the form of synchrotron radiation. We hope you can join us to hear about Dr. Moffat's recent work and findings! Be sure to visit his website ( to learn more about him and his work.

Friday, 14 March 2008, 3:00pm

Dean Myles, Center for Structural Molecular Biology, Oak Ridge National Laboratory
New Opportunities for Neutron Structural Biology
Location: Physics 135

Neutron scattering provides a unique non destructive tool that is able to probe the structure and dynamics of macromolecular complexes and higher order assemblies over a wide range of time and length scales. With the advent of the Spallation Neutron Source (SNS) and the parallel upgrade and development of the 85MW HFIR facility, Oak Ridge National Laboratory (ORNL) is set to become the worlds leading center for the neutron sciences. The field of neutron protein crystallography in particular is likely to benefit enormously from the construction of the Macromolecular Neutron Diffractometer (Mandi) at the SNS, which promises to provide 10-50 fold improvements in performance over the worlds current best instruments. A Center for Structural Molecular Biology has been established at ORNL to develop and support the user access and research programs in neutron-based studies of bio-molecular structure and function. The center includes a dedicated Bio-Deuteration Laboratory for isotopic labeling. These facilities offer new opportunities for the characterization of the structure and dynamics of proteins and macromolecular complexes in crystals, in solution and in membrane associated states.

Friday, 21 March 2008, 3:00pm

Egor Babaev, Assistant Professor, Physics Dept., University of Massachusetts-Amherst
Liquid metallic hydrogen: a quest for novel quantum fluid
Location: Physics 135

Liquid metallic hydrogen is the most abundant state of matter in our planetary system constituting a large part of Jupiter and Saturn. It was also produced in a terrestrial laboratory in shock-wave compression. The problem now is the metallization of hydrogen at static pressures, and at lower temperatures, which is a subject of renewed experimental pursuit spurred by the recent introduction of ultrahard diamond technology. Experiments now reach pressures of 320 GPa, and hydrogen is expected to assume a quantum liquid metallic state at around 400 GPa; the new technology is also expected to lead to diamond cells reaching pressures in 1 TPa range. In this talk, I will discuss what conclusions can be made at the moment regarding the properties of quantum fluid of metallic hydrogen and its possible experimental probes. Remarkably, it is found to violate the quintessential state - defining laws which describe reaction to external field or rotation of presently known quantum fluids, which suggests that liquid metallic hydrogen or deuterium might represent a projected new class of quantum fluids.

Friday, 28 March 2008, 3:00pm

Francesc Ferrer, Case Western Reserve University
Dark matter candidates: from the MeV to the TeV
Location: Physics 135

The precision measurements of the cosmological parameters in the last decade have lead to the standard cosmological model, or LCDM, that seems capable of accounting for all the observations. The LCDM, strikingly, posits that 95% of the present universe is dark, with 25% of the dark sector made of dark matter, associated with bound structures such as galaxies, and 70% of dark energy driving the accelerated expansion of the universe. Weakly interacting particles, a natural candidate for composing the dark matter, may lead to observable fluxes of gamma-rays or neutrinos that could be soon identified by Cerenkov telescopes, satellites and neutrino detectors. I will consider extensions of the standard model of particle physics, that predict a dark matter particle with mass in the MeV-TeV range, and study the observable signals at forthcoming detectors.

Friday, 4 April 2008, 3:00pm

Gary Shiu, Assoc. Professor, University of Wisconsin-Madison
The Promise of String Cosmology
Location: Physics 135

String theory and cosmology are made for each other. Fundamental questions about the early universe call for an understanding of quantum gravity. On the other hand, observational cosmology provides a promising window to probe high energy physics. In this talk, I will describe some recent developments in constructing inflationary models from string theory, the observational signatures of these models, and how one may use data to uncover the details of the underlying string compactification.

Friday, 11 April 2008, 3:00pm

Paul Champion, Dept. of Physics , Northeastern University
Investigations of Coherent Motion and Ligand Binding in Heme and Heme Proteins
Location: Physics 135

Ultrafast kinetic and femtosecond coherence measurements of hemes and heme proteins are discussed. We examine the role of spin-state and the role of protein induced heme distortions as a source of the very different coherent responses for several ferric heme protein systems [1,2]. We also present temperature dependent kinetic measurements [3] of ultrafast diatomic ligand binding to the "bare" protoheme. We find that the binding of CO is temperature dependent and non-exponential over many decades in time, while the binding of NO is exponential and temperature independent. The non-exponential nature of CO binding to protoheme, as well as its relaxation above the solvent glass transition, mimics the kinetics of CO binding to myoglobin (Mb), but on faster time scales. This demonstrates that the non-exponential kinetic response observed for Mb is not necessarily due to the presence of protein conformational substates, but rather is an inherent property of the heme itself. Moreover, the wide range of Arrhenius prefactors (109-1011s-1), observed for CO binding to heme under differing conditions, suggests that entropy production timescales may be an important source of control in this class of biochemical reactions.

Friday, 18 April 2008, 3:00pm

Professor John H. Miller, Jr., Dept. of Physics, Univ. of Houston, and Director of the Texas Center for Superconductivity
Mechanisms and Detection of Biological Molecular Motors
Location: Physics 135

Rotary motors, including ATP synthase and the bacterial flagellar motor, play critical roles in living organisms. ATP synthase produces ATP, life's chemical currency of energy, in all three domains of life: bacteria, archaea, and eukarya. In humans, ATP synthase operates in the inner membranes of mitochondria. I will describe our recently developed electric field driven torque model of ion-driven rotary motors. The model predicts a scaling law that relates torque to the number of ion-carrying subunits in the rotor, the number of stators, and the ion motive force across the membrane. When the F0 complex of ATP synthase is coupled to F1, the model predicts a critical proton motive force below which ATP production drops to zero. In a human, such a drop in ATP would lead to unconsciousness and, eventually, death. We have also been measuring electromagnetic properties, such as impedance and harmonic responses, of live cells, mitochondria, and chloroplasts, in an effort to detect activity of ATP synthase and other enzymes. Dysfunction of mitochondrial enzymes have been implicated in type-2 diabetes, cancer, heart disease, Alzheimer's disease, and numerous specific mitochondrial disorders. Therefore, improved understanding of ATP synthase, and other enzymes of mitochondrial respiratory chain, is broadly significant to human health.

Wednesday, 23 April 2008, 3:00pm

Somendra Parihar, Ph.D. Student, UW-Milwaukee Dept. of Physics
Location: Physics 135


Friday, 25 April 2008, 3:00pm

Jodi Cooley-Sekula, Postdoctoral Scholar, CDMS Experiment, Stanford University
Recoiling Against the Dark Universe: CDMS and the Hunt for Dark Matter
Location: Physics 135

The first evidence for dark matter dates back to observations of the Coma cluster made by Fritz Zwicky in 1933. Since that time, astrophysicists and astronomers have produced compelling evidence for the existence of dark matter and determined that it constitutes the bulk of the matter in the Universe. Despite this fact, the composition of the dark matter remains unknown. One compelling candidate for particle dark matter is the Weakly Interacting Massive Particle (WIMP). Working in a low-background environment in the Soudan Mine, located in northern Minnesota, the CDMS experiment is designed to directly detect interactions between WIMPs and nuclei in its target Ge and Si crystals. In this talk, I will present new results from the CDMS experiment. I will also discuss the current status of CDMS and plans for a future 25-kg experiment, which is planned for operation in SNOLab.

Friday, 2 May 2008, 3:00pm

Danny Marfatia, University of Kansas
Physics of Massive Neutrinos
Location: Physics 135

The discovery that neutrinos have mass has led to a revolution in our understanding of neutrinos. I will summarize the current status of this understanding, identify the open questions, and describe how they may be answered by an ambitious program of experimentation.

Friday, 9 May 2008, 3:00pm

Jose Juan Blanco-Pillado, Tufts University
Cosmic Superstrings
Location: Physics 135

In this talk, I will give a general introduction to the subject of cosmic strings mainly focusing on their formation, dynamics and the potential observational signatures. I will then discuss recent models of cosmology within string theory that suggest the possibility that different types of string-like objects (Cosmic Superstrings) may be formed in the early universe. Finally, I will describe the observational signatures that would help us to identify Cosmic Superstrings in the sky, which represents, up to date, one of the most promising avenues for experimentally test String Theory.

Friday, 16 May 2008, 3:00pm

Dr. Sebastian Wachsmann-Hogiu, Facility Director , NSF Center of Biophotonics, Univ. of CA-Davis
Novel Biophotonics Technologies for Biomedical Applications
Location: Physics 135

Biophotonics is an interdisciplinary field at the interface between physics, chemistry, biology, engineering, and medicine, dealing with the use of light in life sciences and medicine. Photons can be absorbed, emitted, or scattered by biomolecules. During either of these types of interaction, the molecule will, under controlled experimental conditions, preserve its integrity. Therefore, light offers the unique opportunity to study the morphology of biomolecules and the functions they play in their native environment. Taking advantage of a worldwide market of more then $53B, biophotonics has developed new tools, such as multiphoton excitation, Raman spectroscopy/imaging, fluorescence resonance energy transfer, or single molecule fluorescence, to mention just a few, in addition to the more established ones like transmission/absorption, reflection, or fluorescence. Several applications will be presented, including SERS biosensors, identification of cancer stem cells, cancer detection, and gene expression.

Friday, 23 May 2008, 3:00pm

Eun-Ah Kim, Stanford University
In Search of Topological States of Matter with Fractionalized Excitations
Location: Physics 135

Topological states of matter are characterized by emergence of topological invariance in their low-energy, long-distance physics. The very fact that we can postulate states of matter with properties insensitive to local perturbations itself is remarkable. Moreover recent proposals for using appropriate topological states for decoherence free quantum computation added new enthusiasm to the search for such states. In this talk I will discuss two different physical systems which are considered candidates for hosting topological phases: fractional quantum Hall states and Sr2RuO4. I will first give an overview of the connection between topology and fractionalized excitations and highlight features fractionalized excitations of these two very different systems share in common. Before closing the talk, I will bring out open questions critical for harnessing and exploiting these exotic excitations.

Friday, 5 September 2008, 3:00pm

John Beamish, Dept. of Physics , University of Alberta
Flow and Elastic Properties of Helium -- is it a "supersolid?"
Location: Physics 135

Helium's small mass and weak interatomic forces make it a truly quantum material. At temperatures below 2.17 K, liquid 4He becomes a superfluid, with many unusual properties. A classic 1946 experiment by Andronikashvili measured the "superfluid fraction" - the zero viscosity part of the liquid which decoupled from a torsional oscillator. A recent experiment observed similar decoupling for solid 4He below 200 mK, the signature of the "non-classical rotational inertia" which would characterize a new supersolid phase of matter. During the past 4 years, many experiments have looked at other properties of solid helium, but have not yet found definitive proof of other "super" behavior. We have developed new techniques and measured the mechanical (flow and elastic) properties of solid helium, to look for unusual behavior at low temperatures. We see no flow, but our recent shear modulus measurements show a large and unexpected stiffening of the solid at very low temperatures. This is clearly related to the decoupling seen in torsional oscillator experiments, but the exact relationship is not understood. I describe our efforts to understand the roles of crystalline defects and quantum statistics in the behavior of this very quantum solid.

Friday, 12 September 2008, 3:00pm

Marius Schmidt, Asst. Professor, University of Wisconsin-Milwaukee
The Dynamics of Proteins
Location: Physics 135

Dynamics is essential for proteins to function. Protein dynamics lies at the base of all catalytic processes in living matter. Fundamental motions of protein dynamics can be observed by methods having energy resolution such as Moessbauer spectroscopy. In this lecture we will surf on the multidimensional hypersurface of protein conformational space and bring together dynamics and kinetics of these interesting macromolecules.

Friday, 10 October 2008, 3:00pm

Matthew Glenz, Ph.D. Candidate, University of Wisconsin-Milwaukee
Cosmological Inflation and Particle Creation
Location: Physics 135

Cosmological Inflation is the theory that the early universe went through a short period of rapid expansion. During this time, quantum fluctuations on the smallest scales were stretched to lengths that exceeded the observable size of the inflationary universe. After the end of Inflation, the size of the observable universe expanded faster than did the inflated quantum fluctuations, so these perturbations then began to re-enter our observable universe. These perturbations, due to Inflation, were imprinted in the temperature fluctuations of the Cosmic Microwave Background and led to the seeding of large-scale structure. In my talk, I will discuss work done with Distinguished Professor Leonard Parker related to the number of particles created by the expansion of the universe. I will focus on the inflaton particles, which are the particles associated with the single, minimally-coupled scalar field that drives the expansion of the universe in our calculations. These created particles are the quanta that correspond to the fluctuations of the inflaton field. I will relate the spectrum of the particle production to the energy of the particles created, the effective mass of the inflaton, and to the total amount of inflation. These particles can then be used to model Reheating, which is a return to the high temperatures responsible for the success of the Big Bang theory.

Friday, 17 October 2008, 3:00pm

Paul Fenter, Senior Scientist, Argonne National Lab, Dept. of Chemical Sciences and Engineering
Imaging Interfaces with X-rays
Location: Physics 135

Interfaces are central to a broad range of energy technologies, ranging from catalysis, growth of artificial materials (e.g., for solid-state lighting), and the sequestration of energy by-products. Buried (e.g., liquid-solid and solid-solid) interfaces pose a special challenge due to the paucity of probes that can access these interfaces. Synchrotron-based X-ray approaches have substantially clarified the molecular-scale structures at these interfaces, by making use of their unique characteristics (e.g., high penetration through matter, �-scale structural resolution, and straightforward quantification of measured intensities). I will review recent advances in X-ray microscopy, and discuss our ongoing work to extend these capabilities to image interfaces directly with X-rays, an area that has been largely unexplored. Examples will be presented that illustrate the utility of this approach, illustrate the relevant contrast mechanisms that can be used in these systems, and suggest future opportunities.

Friday, 24 October 2008, 3:00pm

Hao Zhang, Associate Professor, University of Wisconsin-Milwaukee
Pushing the Limits of Photoacoustic Imaging
Location: Physics 135

Photoacoustic (PA) imaging is a novel scalable imaging technology that detects laser-induced ultrasonic waves to image the three-dimensional distribution of the optical energy deposition, which is related to the optical absorption. It has been investigated intensively during the past decade due to its capability to achieve both physiologically specific optical absorption contrast and good spatial resolution in deep tissue. Various designs and algorithms for image acquisition and image reconstruction are reported, and potential applications in a wide spectrum of both biomedical research and clinical diagnostics were also demonstrated. In this seminar, I will introduce our current work on PA imaging toward three new directions: ophthalmic imaging, label-free molecular imaging, and real-time full-field imaging.

Friday, 31 October 2008, 3:00pm

Dr. Vasily Astratov, Assoc. Professor, UNC - Charlotte, Dept. of Physics & Optical Science
Mesoscale Photonics: Novel Optical Properties and Applications of Coupled Spherical Microresonators
Location: Physics 135

This talk is devoted to "mesophotonics" - a novel area of photonics dealing with the optical properties of mesoscopic systems of coupled cavities with dimensions in the order of several wavelengths. The focus of this presentation is on developing new concepts related to light transport in systems of coupled microspheres including photonic nanojet-induced modes, percolation of whispering gallery modes and the role of structural disorder and dimensionality. At the device level, these studies stimulate developing designs where coupled cavities are applied to tight focusing micro-probes, sensors, and compact spectrometers.

Friday, 7 November 2008, 3:00pm

Andrey Chabanov, Asst. Professor, Univ. of Texas - San Antonio, Dept. of Physics & Astronomy
Towards Anderson Photon Localization
Location: Physics 135

In analogy with electron localization in insulators, it has been anticipated that photons may be trapped by the constructive interference of waves returning to a point within a strongly scattering medium. Since the statistics of multiply scattered waves is determined by the closeness to the transition between diffusive and localized waves, charting this transition is of fundamental interest for both statistical optics and electronic mesoscopic physics. However, the very possibility of observing photon localization in random systems has been called into question by both the difficulties of achieving strong scattering and of unambiguously detecting electromagnetic localization. Measurements of exponential scaling of transmission and broadened coherent backscattering peaks have not definitively established localization since absorption can also be the source of exponential decay of transmitted intensity. Recently, however, we have shown that the variance of relative fluctuations provides a decisive test for localization, even in the presence of absorption. This also provides a sure guide in the search for photon localization, which can be used to sort out the precise material and structural characteristics that may edge samples towards and potentially across the localization threshold. We also discuss recent reports of photon and ultrasound Anderson localization.

Friday, 14 November 2008, 3:00pm

Teresa Montaruli, UW-Madison and the Univ. of Bari
Results from the Neutrino Telescopes IceCube and ANTARES
Location: Physics 135

Hadronic processes should exist in sources, but most information we have until now on the Universe comes from electromagnetic processes conveyed by photons. Using neutrinos, we can look at the sky with "new glasses." They allow us to observe regions up to tens of Gpc and bring information on the most powerful engines of the universe, like gamma-ray bursts and active galactic nuclei. I will go through the most recent results on the hunt for point-sources of neutrinos in IceCube in the Antarctic ice depths and ANTARES in the sea abyss in front of Toulon. I will discuss the importance of the observation of astrophysical neutrinos, at what level of fluxes we expect to see some signal, and about the power of methods we have implemented to deal with low statistics signals on top of large backgrounds from atmospheric particles. I also will discuss particle physics results that we are deriving using unprecedented statistics of atmospheric neutrinos and muons. This measurement is useful to explore kinematic regions not accessible by colliders and fixed target experiments.

Thursday, 20 November 2008, 3:00pm

Gonzalo J. Olmo, Instituto de Estructura de la Materia - CSIC (Madrid)and Perimeter Institute for Theoretical Physics, Waterloo (Ontario)
Cosmological Inflation: from science fiction to a fully testable theory
Location: Physics 135

The standard model for modern cosmology consists on the Hot Big Bang theory plus an earlier phase of rapid accelerated expansion known as Inflation. The physical processes occurring during inflation successfully solve important questions raised by the HBB model and, in addition, provide a justification for the large scale homogeneity of the Universe as well as a quantum mechanism for the generation of primordial fluctuations, the seeds for galaxies and other cosmic structures. Quantum Mechanics also tells us that inflation must be occurring eternally, producing an infinity of bubble universes disconnected from ours. I will review the HBB model plus inflation and will discuss the quantum processes that generate the primordial seeds for structure formation and lead to eternal inflation (bubble universes).

Friday, 21 November 2008, 3:00pm

David Beebe, University of Wisconsin-Madison
"Tubeless" Microfluidics for Studying Cell Biology
Location: Physics 135

Microfluidic technology holds great promise for improved cell-based assays.The dominant physics of the microscale offer unique functionality and opportunities. These include diffusion-based transport, short diffusion distances, surface tension-based pumping and small volumes. Leveraging these unique attributes, microfluidics offers practical advantages for cell-based assays. In combination, these characteristics provide a new tool for both basic cell biology inquiry as well as the potential to advance clinical diagnostics. Importantly, our "tubeless" microchannel arrays interface seamlessly with existing automated liquid dispensing systems removing an important barrier to the application of microfluidics in both screening and clinical diagnostic applications. I will present a the basic technology platform as well as several examples using the technology to probe cell behavior and communication - including cell migration, stromal-epithelial interactions and growth regulation.

Friday, 5 December 2008 -- JOINT Colloquium with UWM Dept. of Chemistry, 3:00pm

Phil Coppens, Distinguished Professor & Henry M. Woodburn Chair of Chemistry, SUNY - Buffalo
Time resolved X-ray diffraction. Can we image chemical reactions?
Location: Physics 135

Time-resolved photocrystallographic experiments using both monochromatic and Laue techniques will be described and the prospect for ultra-fast time-resolved studies of simple chemical reactions, which are triggers in photo-induced biological processes will be discussed.

Friday, 12 December 2008, 3:00pm

Ranko Richert, Assoc. Professor, Dept. of Chemistry and Biochemistry, Arizona State University
Dielectric and Optical Approaches to Complex Dynamics in Simple Liquids
Location: Physics 135

Liquids are often the precursor of glassy materials, which have found numerous applications in many fields. The dynamics of glass-forming liquids is heterogeneous in nature, with viscosities effectively differing by a factor of one hundred across distances of only few nanometers in simple single compnent liquids. The interest in dynamic heterogeneity has led to various new experimental approaches aimed at detecting the fluctuations in space and time. The talk will outline several such techniques, some based on dielectric relaxation techniques (probe rotation, dielectric hole-burning), others involving optical spectroscopy (triplet state solvation dynamics, optical depolarization). It will be emphasized that more and more observations are emerging that are incompatible with a homogeneous picture, already at the qualitative level.

Friday, 19 December 2008, 3:00pm

Kevin W. Eliceiri, Director , UW-Madison, Laboratory for Optical and Computational Instrumentation
Biophotonics -- Computational and Optical Advances in Biological Imaging
Location: Physics 135

Revolutionary advances in biological and biomedical imaging over the last twenty years have brought about the development of improved methods for non-invasively imaging dynamic biological processes. Of particular significance have been optical (photonic) techniques that have allowed for the visualization and manipulation of molecular and cellular structures within living tissue with minimal perturbation. The importance of these approaches has led to the development of a new field, Biophotonics, the study of photon interaction with biological materials. A fertile area of Biophotonics research and development is in the area of optical instrumentation where collaborative efforts are needed to develop the next generation of optical instrumentation and computational approaches for visualizing and assaying key biological and biomedical phenomena. The efforts of the multidisciplinary UW-Madison Laboratory for Optical and Computational Instrumentation (LOCI), to develop optical and computational approaches for biological and biomedical studies will be presented. These efforts include signal processing approaches for multidimensional image analysis, image informatics, nonlinear optical and intrinsic fluorescence studies, optical histopathology, and adaptive optics for deep imaging of biological tissue.