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Colloquia & Seminars, Spring 2014

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Black Magic: EMC, a Physicist’s Perspective

Speaker: Brett McCarty
Date: Friday, April 4, 2014
Time: 4 PM
Room: 205 Currens Hall

Abstract: Electromagnetic Compatibility (EMC) is colloquially referred to by some engineering professionals as black magic or voodoo. This stigma results from a lack of understanding of some basic physical concepts as well as not appreciating the complexity of real world environments and solutions. In this talk, I will begin with a general overview of EMC followed by an attempt to demystify this field by describing how my degree in physics has helped to prepare me for a career performing "black magic."

About the speaker: 
Brett McCarty graduated from the University of South Carolina with a degree in both History and Physics. He went on to achieve a Master's degree in Condensed Matter Physics from Iowa State University in 2010. He held several odd jobs including census worker, carpenter, and lecturer before landing an Adjunct physics position at St. Ambrose University. After teaching for 3 semesters, he transitioned to the field of EMC. For the past 2 years, he has worked as an Electromagnetic Environmental Effects (E3) engineer at a prominent aerospace company.

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The 17 Position Knob: Tuning Interactions with Rare Earths

Speaker: Dr. Paul Canfield
Date: Monday, March 31, 2014
Time: 11 am
Room: 205 Currens Hall

Abstract: Physicists see the rare earth group of elements as a powerful tool for tuning the properties of materials. Choice or control of rare earths can be used to modify (i) the size of the unit cell, (ii) the size of local moment and degree of coupling, (iii) the size and direction of magnetic anisotropy, (iv) the amount of entropy that can be removed at low temperatures, (v) the degree of band filling, and/or (vi) the degree of hybridization. In this seminar, I will provide an overview and examples of how this region of the periodic table can be used to guide and inspire research into a wide swatch of novel materials and ground states. By using rare earths as a focal point we can cut across superconductivity, metamagnetism, spinglasses, quasicrystals and quantum criticality all for the price of a single admission.

About the speaker: 
Dr. Paul C Canfield graduated, Suma Cum Laude, with a BS in Physics from the University of Virginia in 1983. He then performed his Master and Ph.D. work at UCLA with Professor George Gruner and received his Ph.D. in Experimental Condensed Matter physics in 1990. From 1990 – 1993 Dr. Canfield was a post-doctoral researcher in Los Alamos National Laboratory working with Drs. Joe Thompson and Zachary Fisk. In 1993 Dr. Canfield went to Ames Laboratory and Iowa State University and, over the past 20 years, has become a Senior Physicist in Ames Laboratory and a Distinguished Professor of Physics, holding the Robert Allen Wright Professorship. Dr. Canfield’s research is centered on the design, discovery, growth and characterization of novel electronic and magnetic materials. He has made key contributions to the fields of superconductivity, heavy fermions, quantum criticality, quasicrystals, spinglasses, local-moment metamagnetism and metal-to-insulator transitions. He has helped to educate and train researchers in experimental, new-materials-physics throughout the world, emphasizing the need to tightly couple growth (often in single crystal form) and measurement of new materials. Dr. Canfield is a Fellow of the American Physical Society. He was awarded the 2011 DOE Lawrence Award for Condensed Matter Physics.

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Exploring the Electronic Properties of Layered Materials

Speaker: Dr. Andrew Stollenwerk
Date: Friday, March 28, 2014
Time: 4 pm
Room: 205 Currens Hall

Abstract: Layered materials such as graphite consist of two-dimensional molecular sheets held together by weak electrostatic forces. The weak interlayer binding makes it possible to separate the crystal into single molecular sheets. These two-dimensional crystals can have properties that differ significantly from the "mother crystal." Perhaps the most well-known of these two-dimensional crystals is graphene, formed by peeling away a single layer of graphite. Graphene in its purest state is strong, light, and an excellent conductor of heat and electricity. The seemingly limitless potential applications combined with the need to understand the fundamental physics have made graphene a superstar of condensed matter physics. This makes other layered materials jealous. As such, this colloquium will explore some of the other similarly structured materials that have been overlooked as well as several techniques used to study the electronic properties of crystals that are inherently lacking in the third dimension.

About the speaker: 
Dr. Stollenwerk received a B.S. in physics and a B.A. in mathematics at Miami University in 2002. His graduate work was performed at the University at Albany SUNY, where he received his M.S. in physics in 2004 and his Ph.D. in Nanoscience in 2007. He joined the physics department at the University of Northern Iowa in 2009 after a two year postdoctoral fellowship at Harvard University studying single electron charging in colloidal quantum dots.

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IN VIVO STUDIES OF ACTIVE PROCESSES IN THE ESCHERICHIA COLI NUCLEOID

Speaker: Dr. Rudra Kafle
Date: Friday, February 28, 2014
Time: 4 pm
Room: 205 Currens Hall

Abstract: The cell is the site of actively motor-driven processes which drive the intracellular environment far from thermodynamic equilibrium. The dynamics of biological macromolecules such as DNA in such an environment are complex and subject to a multitude of constraints and forces. Inspired by our in vitro studies of DNA looping with optical tweezers that showed that additional non-thermal fluctuations in the DNA can substantially enhance the formation of regulatory DNA-protein complexes, we study the conformational fluctuations of chromosomal DNA in vivo in Escherichia coli by Fluorescence Correlation Spectroscopy (FCS).

Conformational fluctuations of the DNA move the bound fluorophores stochastically into the diffraction-limited excitation volume of a focused laser beam in a confocal microscope. From the time correlation functions of the measured fluorescence intensity, we quantify the fluctuations of the DNA as measured by its time-dependent mean square displacement, and the viscoelastic moduli of the nucleoid. These quantities in live cells significantly differ from the ATP-depleted dead cells on longer time scales, indicating that the fluctuations on longer time scale may be driven by active processes involving molecular motors that generate forces by ATP hydrolysis. On shorter time scales, we see little difference between live and dead cells, suggesting that the processes on corresponding short length scales rely primarily on thermally-driven diffusive mechanisms. We also note that the rheological properties of E. coli nucleoid significantly change when the ATP hydrolysis in cells is inhibited.

About the speaker: 
Dr. Rudra Kafle is a postdoctoral research fellow in Biophysics Department at University of Michigan. His current research is focused on theoretical and experimental studies of active processes in cells and their roles in gene regulation. Dr. Kafle received his PhD in Theoretical Atomic Physics from Worcester Polytechnic Institute (WPI) Massachusetts in 2012. His PhD dissertation was on theoretical analysis of Bose-Einstein condensate (BEC) atom interferometers. During his PhD studies, Dr. Kafle visited Los Alamos National Laboratory where he did theoretical studies on Berry-gauge tuned BEC gyroscopes. Originally from Nepal, Dr. Kafle was a graduate student and a recipient of Dr. Yan N. Lwin Physics Scholarship in Physics Department at Western Illinois University.

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The Physics of Super Resolution: from atom localization to microscopy

Speaker: Dr. Kishor T. Kapale
Date: Friday, February 21, 2014
Time: 4 pm
Room: 205 Currens Hall

Abstract: The Rayleigh diffraction limit for resolution is not fundamental as it hinges on the use of a particular optical setup. Several classical optical techniques, such as monitoring the evanescent fields, already allow resolution beyond the diffraction limit, however, only by a small factor. Recently several quantum tricks have emerged to obtain resolution much beyond the diffraction limit. Employing spatially dependent light-matter interaction allows extreme sub-wavelength resolution in determining the position of an atom. The idea of super-resolution has also found applications in the area of microscopy. This talk will concentrate on throwing light on the techniques to go beyond the diffraction limit for variety of application such as sub-nano fabrication, imaging and microscopy. In this context, a natural question arises: Is there an ultimate limit to resolution? This question will be addressed with an eye on the limitations of these super-resolution proposals.

Atom Localization Simple

About the speaker: 
Dr. Kapale is a theoretical physicist whose research focuses on quantum optics, atomic optics, quantum information theory and applied quantum physics. Dr. Kapale did his MS in Physics from Indian Institute of Technology, Bombay (now Mumbai). He did his PhD work at Texas A&M in the area of theoretical quantum optics. After spending a semester at Princeton he moved to Jet Propulsion Laboratory, California Institute of Technology as a National Research Council Research Associate and NASA Postdoctoral Fellow. He joined the WIU Department of Physics in Fall of 2007.

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Sample Synthesis and Neutron Scattering: Complementary Experimental Techniques

Speaker: Dr. Alex Thaler
Date: Friday, January 24, 2014
Time: 4 pm
Room: 205 Currens Hall

Abstract: Neutron scattering is a very powerful probe in condensed matter physics. Through elastic scattering, neutrons can directly measure crystallographic structure and both local and bulk static magnetic structure. Through inelastic scattering, they can be used to probe excitation states such as phonons, magnons, and spin/charge density waves. By selecting an appropriate temperature, they may be used to probe a wide range of structure sizes and energy scales. The price neutron scattering pays for these strengths is fairly stringent sample requirements, so many sample growers shy away from providing materials to neutron scattering groups. As a result, neutron scattering groups have become increasingly involved in synthesizing their own materials, particularly at those institutions which do not have a strong extant synthesis group. I will discuss some of the challenges of being a sample grower in a neutron scattering group and some of the techniques we use to get around them. I will also showcase some of the unique opportunities afforded to a combined group such as ours. Finally, I will talk about some of the projects which we have worked on which use these techniques.

About the speaker:
Dr. Alex Thaler is a postdoctoral research associate at the Seitz Material Lab on the campus of the University of Illinois at Urbana-Champaign

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