Physics Colloquium

October 28, 2014

Professor Kaden Hazzard
Department of Physics
Rice University
Houston, Texas
Tuesday, October 28, 2014,
3 p.m., Room 101, Farrington Building

The miracle of molecules: quantum magnetism in nonequilibrium ultracold matter

Abstract: How do large collections of objects produce emergent phenomena that are drastically different from the individual constituents?" This challenging question pervades science. In physics, the components are often quantum - electrons, quarks, atoms, or photons.  NanoKelvin-scale ultracold matter provides unique insights into emergent quantum behavior, because ultracold experiments are extremely flexible and well-characterized. Recently-produced cold molecules add capabilities to the ultracold toolbox that are unavailable with atoms. I will discuss how joint experiment-theory work has harnessed these new capabilities to experimentally realize interacting spin models, and how measuring their far-from-equilibrium dynamics led us to develop new theoretical methods. 

October 14, 2014

Professor Lowell Wood
Department of Physics
University of Houston
Houston, Texas
Tuesday, October 14, 2014, 3 p.m., Room 101, Farrington Building

Optical Beam Shaping

Abstract: Optical beam shaping has been one of the most important topics in classical optics for the past 25 years.  In this talk, I will review some of the basic methods for producing novel and useful beam shapes, beginning with basic refractive and reflective optical elements, then proceeding on to diffractive optical elements (DOEs), and ending with beam shaping using naturally occurring interference/diffraction patterns. I will use cusp-shaped lenses and mirrors as examples of simple optical elements and discuss topics such as quasi-nondiffracting Bessel beams, the Talbot effect (self-imaging), apodization, and inverse apodization. As a brief review for everyone, far-field (Fraunhofer) and near-field (Fresnel) diffraction theory will be discussed.

September 10, 2014

Michael G Strauss, Ph.D.
David Ross Boyd Professor of Physics
Research Field: Experimental Particle Physics
The University of Oklahoma
Homer L Dodge Department of Physics and Astronomy
Wednesday, September 10, 3 p.m., Room 105, Farrington Building

Properties of the Higgs Boson

Abstract: In July 2012 the ATLAS and CMS collaborations at the CERN Large Hadron collider announced the discovery of a Boson consistent with the predicted standard model Higgs Boson.  Since that discovery, further measurements have given insight into the properties of this particle.  This talk will discuss the importance of the Higgs Boson within the standard model, the discovery of this new Boson, and subsequent measurements of its properties.

March 25, 2014

Professor Jason Hafner
Department of Physics
Rice University, Houston, Texas
Tuesday, March 25, 3 p.m., Room 101, Farrington Building 

Plasmonics for Membrane Structural Biology

Abstract: Gold nanoparticles focus light to the nanometer scale at their surface and enhance spectroscopic signals from molecules bound there. This effect, called Surface Enhanced Raman Scattering (SERS), has been widely studied as a chemical sensing mechanism, but may also serve as a powerful analytical method to study interfacial chemistry at nanoparticle surfaces. We are pursuing SERS as a new method for membrane structural biology by surrounding nanoparticles with lipid membranes.  Results from the early stages of this project will be discussed.

February 19, 2014

Professor Le Xie
Assistant Professor, Department of Electrical and Computer Engineering
Texas A&M University
Wednesday, February 19, 2014, 3 P.M., Room 101, Farrington Building

Integrating Data-driven and Physics-based Analytics for Predictive Operations in Electric Energy Systems

This talk concerns the handling and utilization of streaming online data (such as synchrophasors and smart meters) for enhancing power system real-time physical and market operations. The first part of the talk analyzes the dimensionality of the phasor measurement unit (PMU) data under both normal and abnormal conditions. We observe that the underlying dimensionality is extremely low despite the large dimensions of the raw PMU measurement data. Justification of this observation is proposed using linear dynamical systems theory. A novel early anomaly detection algorithm based on the switch of core subspace at the occurrence of an event is proposed. The second part of the talk presents our empirical work of quantifying benefits of incorporating look-ahead dispatch with responsive demand from Electric Reliability Council of Texas (ERCOT) data. Demand elasticity at ERCOT is estimated, and the market price behavior with price responsive demand is analyzed.  We conclude the talk with suggestion of several open research questions that could benefit a lot from industry-academia collaboration.

Speaker bio: Le Xie is an Assistant Professor in the Department of Electrical and Computer Engineering at Texas A&M University, College Station, Texas, where he is affiliated with the Electric Power and Power Electronics Group. He received his B.E. in Electrical Engineering from Tsinghua University, Beijing, China in 2004. He received S.M. in Engineering Sciences from Harvard University in June 2005. He obtained his Ph.D. from Electric Energy Systems Group (EESG) in the Department of Electrical and Computer Engineering at Carnegie Mellon University in 2009. His industry experience includes an internship in 2006 at ISO-New England and an internship at Edison Mission Energy Marketing and Trading in 2007. His research interest includes modeling and control of large-scale complex systems, smart grid applications in support of variable energy integration, and electricity markets. 

Dr. Xie received a National Science Foundation CAREER Award, and the Department of Energy Oak Ridge Associated Universities Ralph E. Powe Junior Faculty Enhancement Award. He is an Editor of IEEE Transactions on Smart Grid, and the founding chair of IEEE PES Power System Analysis, Computing and Economics Committee Task Force on Big Data Analytics for Grid Operations. He and his students received the Best Paper award at North American Power Symposium 2012 and IEEE Smart Grid Comm conference 2012. 


February 10, 2014

Professor Ben Janesko
Assistant Professor of Chemistry
Texas Christian University
Monday, February 10, 2014, 3 P.M., Room 101, Farrington Building

Density Functional Theory for Surface Science

Electronic structure simulations of molecules on semiconducting  and metallic surfaces give insight into a range of problems, from heterogeneous catalysis to the synthesis and properties of nanomaterials. State-of-the-art approximations based on Kohn-Sham density functional theory provide useful insights. However, they are limited by the need to approximate the formally exact exchange-correlation (XC) density functional incorporating all many-body effects. To illustrate, XC approximations typically used to model chemical reactions on surfaces give an average ten order of magnitude error in accurately measured gas-phase room-temperature reaction rates. I discuss our work on developing new XC functionals and extending successful approximations to surfaces.

January 27, 2014

Professor Lucas Macri
Physics and Astronomy
Texas A & M University
Monday, January 27, 3 P.M., Room 105, Farrington Building

Probing the Cosmic Expansion: The Age of the Universe and Dark Energy

What is the nature of dark energy? Is it Einstein's "cosmological constant" or perhaps a dynamical inflation-like scalar field? The answer to this fundamental question is driving the development of several large-scale astronomical projects over the next decade. In conjunction with these major projects, an accurate and precise measurement of the age of the Universe (via the Hubble constant) plays a critical role in constraining the properties of dark energy and other cosmological parameters.

In this talk I will review the state of the field, describe several probes of cosmic expansion, and summarize my ongoing research on Cepheid variables using the Hubble Space Telescope and other facilities to measure the Hubble constant with a total uncertainty of only 3%. I will conclude by discussing future prospects for the Cosmic Distance Scale in the age of the Giant Magellan Telescope and the James Webb Space Telescope.

November 12, 2013

Natalie Gosnell
University of Wisconsin-Madison

Tuesday, November 12, 2013, 3:30 p.m.
Room 105, Farrington Building

The Companions to Blue Straggler Stars in Open Cluster NGC 188

Historically, blue straggler stars in stellar clusters (the members of which are about the same age) are stars that are unusually blue and bright compared to what is expected. From standard stellar evolutionary theory they should have evolved off the main-sequence long ago to become giants and white dwarfs, so their existence has remained a mystery. We now believe blue straggler stars trace the interface between two great fields of astrophysics: stellar evolution and stellar dynamics. They define new stellar evolutionary pathways, and they challenge our understanding of star cluster dynamics and binary star evolution. Possible formation scenarios for blue stragglers include mass transfer in binary systems, stellar collisions during dynamical encounters, and stellar mergers in triple systems. I will discuss my dissertation project, utilizing the Hubble Space Telescope to observationally determine the formation mechanism of blue stragglers in the old open cluster NGC 188.

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