February 12, 2015
Dr. Peter Brown
Department of Physics and Astronomy
Texas A&M University
Thursday, February 12, 3:30 P.M.
Farrington Room 209
Calibrating Exploding Stars for Precision Cosmology
Type Ia supernovae are one kind of "standard candle" used to measure distances and the expansion rate of the universe. With the hundreds or thousands of supernovae used in current analyses, the systematic errors now dominate over the statistical errors. Many of these systematics are poorly understood but are expected to have strong signatures at ultraviolet wavelengths. I am using the Swift Gamma-Ray Burst Explorer to observe supernovae in the ultraviolet. I will show constraints on progenitor systems and extinction derived from Swift ultraviolet observations. I will also discuss the effects expected from metallicity, asymmetry, and explosion differences. I will also show recently discovered evidence for a possible change with redshift in the supernova Ia population.
February 9, 2015
Mr. Troy Schaudt
Wolfram Research, Inc.
Monday, February 9, 2015
Lowman Student Center, Room 315
"Mathematica 10 in Education and Research"
This talk illustrates capabilities in Mathematica 10 and other Wolfram technologies that are directly applicable for use in teaching and research on campus. Topics of these technical talks include:
- Enter calculations in everyday English, or using the flexible Wolfram Language
- Visualize data, functions, surfaces, and more in 2D or 3D
- Store and share documents locally or in the Wolfram Cloud
- Use the Predictive Interface to get suggestions for the next useful calculation or function options
- Access trillions of bits of on-demand data
- Use semantic import to enrich your data using Wolfram curated data
- Easily turn static examples into mouse-driven, dynamic applications
- Access 10,000 free course-ready applications
- Utilize the Wolfram Language's wide scope of built-in functions, or create your own
- Get deep support for specialized areas including machine learning, time series, image processing, parallelization, and control systems, with no add-ons required
Current users will benefit from seeing the many improvements and new features of Mathematica 10 but prior knowledge of Mathematica is not required.
January 27, 2015
Dr. Jason Nguyen
Department of Physics
Thursday, January 29, 2015
Farrington Room 209
Collisions of Matter-Wave Solitons
Solitons are non-dispersive waves which occur in many different areas ranging from cold-atomic systems, non-linear optics, biological systems, fluid mechanics, and even cloud formations. A unique property of solitons is that they propagate without a change in their shape, amplitude, or velocity, which is a direct consequence of the integrability of the mathematical models that describe them. These properties remain valid even after collisions, with the only evidence of a collision being a change in the solitons trajectory.
Using a Feshbach resonance to tune the interactions from repulsive to slightly attractive, we form pairs of matter-wave solitons in a quasi-one-dimensional harmonic trap from a BEC of 7Li atoms. Once formed, we allow the solitons to collide as they oscillate in the trap. Depending on the strength of the nonlinearity, and the relative phase between the soliton pair, we observe a remarkably different behavior ranging from annihilation to persistent oscillations. We also measure a shift in the oscillation frequency that depends on the strength of the nonlinearity, indicating a change in the soliton trajectory with each collision event.
December 1, 2014
Mr. Chunhui Wang
White Bay Group
(Formerly with 17Nano, LLC)
Monday, December 1, 2014
Farrington Room 107
8:00 a.m. (NOTE special time)
Career Differences between a Trader and a Financial Engineer
November 21, 2014
Professor Robert C. Webb
Texas A&M University
College Station, Texas
Friday, November 21, 2014
Farrington Room 105
Searching for Dark Matter with the LUX and LZ detectors at the Sanford Underground Research Facility
The Large Underground Xenon (LUX) experiment, a dual phase xenon time projection chamber, has been operated underground at the Sanford Underground Research Facility since February 2013 and the next generation dark matter detector based on this same technology (LZ) is in the planning stages. I will review the case for dark matter and report on the first WIMP search dataset from LUX, taken during the period from April to August 2013. I will then go on to outline the near and long term prospects for the discovery of dark matter in the coming decade.
November 10, 2014
Margaret S. Cheung
University of Houston, Department of Physics; Center for Theoretical Biological Physics, Rice University
Monday, November 10, 2014
Farrington Room 209
Protein folding and recognition in the cell -- an in silico approach
I will present the research from my group using the approach of coarse-grained molecular simulations for the investigation of protein folding and protein-protein interactions in a cellular environment. We used a low-resolution model for the representation of proteins and macromolecules that mimic a jam-packed space inside a cell. We made these low-resolution models act like “the real thing” by keeping the physics in its dynamics and the principle of chemical interactions between macromolecules in the simulations. With this approach, we are able to characterize the mechanism of protein folding and protein-protein interactions that involve structurally large rearrangement in the presence of dominant forces inside a cell, such as the volume exclusion from the macromolecular crowding effect and the electrostatic interactions at several ionic strengths. Based on simple ideas of modeling a structurally complex system, I will report several new discoveries and testable predictions from our computational studies.
October 28, 2014
Professor Kaden Hazzard
Department of Physics
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
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
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.