Full Abstracts

January 27, 2010

Gil Pacey, Miami University

Department of Chemistry and Biochemistry

"What does one do at IDCAST”
The Institute for Development Commercialization of Advanced Sensor Technology (IDCAST), is an Ohio Third Frontier Wright Center for Innovation.   IDCAST’s mission is to establish collaboration between academia, government, and industry to develop new sensor technology in both remote and Chemical Biological, Radiological, Nuclear and Explosive (CBRNE) sensing.  Seven Ohio universities (Central State University, Miami University, Ohio State University, University of Cincinnati, University of Dayton, University of Toledo, and Wright State University), over 50 commercial companies, and 6 government laboratories including the Air Force Research Laboratory (AFRL) at Wright Patterson Air Force base are members of IDCAST. The IDCAST membership is in a position to provide cutting edge research projects, technical services, and commercialization experience in a variety of areas to its members.  In just its third year of existence, IDCAST has produced new technologies that have created nearly 300 jobs.  The seminar will describe the types of research being performed in the IDCAST collaborations.
 

February 3, 2010

Timothy Dowling, University of Louisville

"Shear Instability: A Bountiful Yield from a Field Sown by Mathematicians, Meteorologists, and Other Pessimists"
Shear instability and stability are at the heart of geophysical fluid dynamics, governing the birth, life, and death of vortices and jet streams.  Most systems admit two distinct branches of stability criteria, corresponding to the fact that closed contours around a point, the signature of stability in phase space, can refer to the topographic map of either a hill or a depression. In the case of meteorology, one branch of shear-instability theory has dominated the other in the literature and textbooks for over a century, for the single reason that it is easier to prove mathematically than the other.  However, the last couple of decades have yielded observations, especially from the giant planets but also from the terrestrial planets, including Earth, that suggest that the harder-to-prove branch may be the only one that is relevant to geophysical fluid dynamics.  This state of affairs is well illustrated by the fact that Jupiter's jet streams strongly violate all the shear-stability theorems commonly found in dynamic meteorology textbooks, and yet are observed to be stable for decades.  By prying the harder-to-prove theory from the grip of mathematicians, major progress has recently been achieved, including a successful prediction of the deep winds of Jupiter, the most precise estimate of the rotation rate of Saturn to date, and a deeper understanding of the nature of marginal stability of jet streams and currents on Earth and the planets.

February 10, 2010  Cancelled Due to Snow Storm, to be rescheduled

Yogesh Joglekar, Indiana University-Purdue University

"The elusive memristor: signatures in basic electrical circuits"

Resistor R, capacitor C, and an inductor L are the three well-known circuit elements that form the basis of circuit theory taught in introductory physics and electrical engineering courses. More than three decades ago, the existence of a fourth basic element, called memristor M (short for memory resistor), was postulated based on symmetry arguments; however, it was experimentally realized just last year. In this talk, I will present a tutorial on memristive systems. After a brief review of the experimental results, I will discuss the memristor model and present analytical results for the current-voltage characteristics that show hysteresis. I will present the properties of memristor-capacitor (MC), memristor-inductor (ML), and memristor-capacitor-inductor (MCL) circuits, and show that the unusual propertie of basic electrical circuits with a memristor  are closely related to, and can be used to distinguish between, models of ionic drift inside the memristor. This tutorial can be easily adapted for introductory courses. I will conclude with a few open questions in this exciting field.

February 17, 2010
 Xinyu Liu, University of Notre Dame

"Magnetic anisotropy, interlayer exchange coupling, and spin manipulation in GaMnAs"
The newly developing spintronics technology requires materials that allow control of both the charge and the spin degrees of freedom of the charge carriers. Ferromagnetic semiconductors (such as GaMnAs) are considered suitable due to simultaneous presence of magnetic order and of semiconducting properties. In this seminar talk, we present the recent research and accomplishments regarding three technologically important properties – magnetic anisotropy, interlayer exchange coupling, and spin manipulation – of GaMnAs-based heterostructures, with an eye on their potential role in practical multifunctional devices.

 
February 24, 2010
Axel Hoffmann, Argonne National Laboratory
Materials Science Division and Center for Nanoscale Materials
"Teaching Electrons New Tricks: Pure Spin Currents"
One of the ultimate challenges for the semiconducting industry is increased power consumption as the devices reach ever-smaller dimensions.  One possible solution to this problem is to directly incorporate ferromagnetic materials into memory and logic in order to retain information without the need of a continuous power drain.  Up to now, most spin-transport phenomena have been measured in quasi-one-dimensional structures, where charge and spin transport are parallel by default.  But recently there has been increased interest in investigating two-dimensional spin-transport structures, where charge and spin currents can be separated due to the non-conserved nature of the spin.   This permits the generation of pure spin currents, which can have additional advantages in terms of power dissipation, since, in principle, spin information can be transmitted without the need of actual spin motion, thus potentially significantly reducing dissipative losses.  In this talk I will review our own work on pure spin currents based on spin current generation due to electrical injection and spin pumping.   This work allows us to get a better fundamental understanding of spin relaxation and scattering in normal metals, which ultimately will be crucial for practical implementation of pure spin currents.

Work supported by UChicago Argonne, LLC, operator of Argonne National Laboratory, a U.S. Department of Energy Office of Science laboratory, operated under contract No. DE AC02-06CH11357.
  

March 3, 2010
Justin J. Link, PhD, Xavier University
"Proteins from a Physicist’s Point of View"
Life as we know it would not be possible without the functions of proteins.  Understanding their function can be determined by our ability to map out structures and dynamics of these macromolecules.  The past decades have witnessed great progress in the determination of structures, but the study of dynamics is much less advanced.  One of the major challenges in modern biophysics is to characterize such dynamics at the atomic scale and thus elucidate the relevant molecular mechanisms.  With femtosecond resolution, it is now possible to observe atomic motions in real time.  This temporal resolution is crucial for a complete description of the elementary dynamics which is an essential determinant of the function at longer times.  It is with integration of femtosecond spectroscopy and molecular biology techniques such as site-directed mutagenesis that these fundamental dynamics can be revealed.  Ligand dynamics in myoglobin and cytochrome c provide excellent model systems for the study of ultrafast protein dynamics.  Observation and engineering of the intrinsic amino acid tryptophan position relative to the prosthetic heme group allows for both local and global protein dynamics studies presented here.

March 24, 2010
Craig Benson, Wyle Laboratories, Inc.
“Non-Destructive Testing (NDT): Applied Principles of Physics”
Non-Destructive Testing involves testing an object of interest without harming it.  Many different Non-Destructive Testing methods can be used to inspect objects ranging from the entire space shuttle to the diagnostic testing of humans.  Various Non-Destructive Testing methods employ various laws of physics ranging from Acoustics to X-ray Diffraction.  This talk will discuss various methods of Non-Destructive Testing, including some of the inherent physics as the advantages, disadvantages, limitations, and typical applications of the given methods.  In summary this talk will illustrate the broad use of physics throughout the field of Non-Destructive Testing.
 

March 31, 2010
Charlotte Elster, Ohio University

"Let’s go Skating and do some Physics on the Ice"
Skating is fun! Figure skating is fun, great exercise and beautiful to watch. Though I skated as a child on frozen ponds, I started figure skating only a few years ago. This talk will discuss slippery ice and how our blades work. Then the intricate interplay of linear and angular momentum that characterizes the beauty and challenge of figure skating will be explained with selected examples. Above all I want to share my love for the sports while looking at it through the lens of a physicist.

April 14, 2010

Andrew D. Sommers, Miami University

"Condensate Droplet Behavior on Anisotropic Surfaces: A Condensed View of Surface Wettability and Control"
Minimizing water retention on aluminum is important in the design of energy-efficient heat exchangers because water retention can deteriorate the performance of such devices. It increases the air-side pressure drop, provides a site for biological activity, and can decrease the sensible heat transfer coefficient thereby increasing energy consumption. In this research, a method for patterning micro-channels on aluminum is described for the purpose of exploiting those features to affect the overall surface wettability. It has been shown that this surface anisotropy not only affects the shape of the three-phase contact line but it also creates a favorable direction for water droplet shedding thereby promoting drainage. This is because the channels provide preferential drainage paths for water droplets to flow off the surface.

Experimental data have shown that droplets placed on micro-grooved aluminum surfaces using a micro-syringe exhibit an increased apparent contact angle, and for droplets condensed on these etched surfaces, up to a 50% reduction in the volume needed for the onset of droplet sliding is manifest. In an effort to provide guidance for the development of these enhanced surfaces, a mechanistic model for droplet retention on these surfaces will also be presented.

This work is supported by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) and SAPA Heat Transfer.

April 21, 2010

Joseph R. Leach, University of California, San Francisco

"Patient-Specific Mechanical Analysis of Atherosclerotic Arteries with Resolved Pre- and Post-Rupture Intraplaque Composition"
Atherosclerotic plaque rupture at the carotid bifurcation is a major cause of stroke. While plaques vulnerable to rupture progress under significant influence from the local biochemical environment, and often experience a chronic or acute inflammatory process, mechanical forces are also of importance.  Finite element studies have been conducted on models of diseased vessels to elucidate the effects of lesion characteristics on the stresses within plaque materials.  Ultimately, it is hoped that patient-specific biomechanical analyses may serve as a robust clinical tool to assess the rupture potential for any particular lesion, allowing better stratification of patients into the most appropriate treatment plans.  I will present modeling techniques developed to accurately and efficiently study arterial mechanics on a patient-specific basis.  Results will be shown for a fluid-structure interaction analysis of a patient for whom pre- and post-rupture imaging data is available.  The effects of imaging imprecision on the calculated stress fields are characterized to further elucidate challenges of image-based modeling.  We find that plaque rupture location and extent, derived from post-rupture imaging data, correspond well to a region of elevation in first principal stress within the fibrous plaque layer of the lesion.
 

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