Physics Colloquium

March 14, 2016

Professor Jiefu Chen
Department of Electrical and Computer Engineering
University of Houston
Monday, March 14, 2 p.m.
Farrington Room 107

A Semi analytical Finite Element Scheme Developed in the Hamiltonian System, and Its Applications in Well Logging

A semi analytical finite element method is proposed to simulate electromagnetic problems in layered media. A piecewise homogeneous structure is divided into several layers. Each layer is uniform in the longitudinal direction, and the distributions of geometry and material can be arbitrary on the transverse plane, or cross-section of the layer. To develop this semianalytical finite element scheme, the standard functional corresponding to the vector wave equation is cast to a new form in the Hamiltonian system based on dual variables, which are transverse components of both electric and magnetic fields on the cross-section of the layer. 2D finite elements are employed to discretize the cross-section, and a high precision integration scheme based on the Riccati equations is used to exploit the longitudinal homogeneity in the layer. By transforming a 3D layered problem into a series of 2D problems, this semianalytical finite element method can save a great amount of computational costs and meanwhile achieve a higher level of accuracy compared with conventional finite element schemes. The flexibility of this semianalytical method can be greatly increased by hybridization with conventional finite elements, and this strategy works well for layered structures with local inhomogeneities such as borehole washouts. Examples will be given to show the applications of this method in resistivity well logging and electromagnetic telemetry.

March 4, 2016

Adam Reppond

L3 Communications
Greenville, Texas
Farrington Room 209
Friday, March 4, 2 p.m.


Adam is a distinguished alumnus of the SHSU Physics Department.

February 26, 2016

Professor Alex Zakhidov
Department of Physics
Texas State University
San Marcos, Texas
Farrington Room 209
Friday, February 26, 2 p.m.

Physics of Organic Semiconductor Devices:Materials, Fundamentals, Technologies and Applications


Organic electronics and optoelectronics (OE) are fast developing branches of modern science and technology that are aiming to compliment conventional inorganic semiconductors with light, inexpensive, and flexible organic materials. A traditional approach in OE is to build the very same device architecture and optimize different parameters in order to obtain the highest device performance. Practically, this approach proved to be very effective; however, it lacks scientific challenges and thus, obtained fundamental knowledge is marginal. When conceptually a new idea is introduced into device’s design, truly novel information can be revealed about mechanisms of device operation resulting in achieving a performance breakthrough. This can be done by using either one or a combination of following strategies: i) new engineering technology for device fabrication, ii) new type of devices, iii) utilization of a new class of materials.

In my talk, I am going to show how those strategies facilitate recent progress in the field of OE. In particular, I will describe recently discovered inversion mode organic thin film transistors enabled by molecular doping technology. Another great example of enabling technology is organic friendly orthogonal photolithography technology, which allowed building of e.g. high-voltage organic solar cells, OTFT based circuits and RGB OLED displays.

New device architecture creates a new platform to study the property of materials and interfaces. Organic semiconductor microcavities (OMC) e.g. can confine the light on a nanoscale and provide a laboratory for semiconductor quantum optics and photonics. Strongly localized Frenkel excitons in organic semiconductors exhibit a much higher binding energy and oscillator strength than the Wannier-Mott excitons found in inorganic semiconductors. In addition, virtually unlimited material design possibilities and low re-absorption due to large Stokes shifts make OMC attractive for studying linear and non-linear optical effects. In our recent work, we experimentally demonstrated that proper design of metal electrodes inside the OMC doesn’t negatively affect the lasing threshold.

Finally, recently employed new class of materials organic-inorganic halide perovskites made a revolution in thin film solar cells. CH3NH3PbX3 (X = Cl, Br, or I) perovskites made a rapid progress in power conversion efficiency from 3.8% in 2009 up to 21% in 2015. I will make a quick review on that topic and try to explain why this particular class of materials outperforms organic solar cells and what are the challenges facing practical application.

February 10, 2015


Associate Dean and Professor Anne Gaillard
Department of Biology
Sam Houston State University
Huntsville, Texas
Farrington Room 209
Wednesday, February 10, 3:00 p.m.

Solid-state signal transduction and fluid dynamics of cilia from the green alga, Chlamydomonas



Chlamydomonas is a unicellular green alga with two cilia that are used for swimming in liquid environments.  The cilia are primarily composed of a complex, scaffold-like molecular machine known as the axoneme.  Various signaling molecules interact with components of the axoneme to produce coordinated motility consisting of precise ciliary bending patterns.  Understanding how chemical messengers lead to changes in axonemal machinery that result in distinct swimming abilities is the overall goal of this work.

January 28, 2015

Dr. Farzam Javadpour
Research Scientist
Bureau of Economic Geology
Jackson School of Geosciences
University of Texas at Austin
Thursday, January 28, 3:00 p.m.
Farrington Room 107

Nanophysical Aspects of Geological Formation


Nanoscience is the science of matter at nanoscale—for example one millimeter is equal to one million nanometer and the size of a methane molecule is 0.5 nanometer. We utilize nanoscience in two major research efforts related to hydrocarbon reservoirs. First is the exploration of the fundamental physics of natural nanosystems, including unconventional shale gas reservoirs with pores as small as few nanometers; second is the use of engineered nanoparticles (10-100 nanometers) to improve reservoir characterization and enhanced oil recovery. Although these applications are different, the governing physics at nanoscale carry over between the two, and some experimental techniques can be used for both subfields. In this talk we highlight the nanoscale features of shale gas reservoirs and describe the experimental methods and mathematical/numerical models that we used to study such systems. We also summarize fundamental works in understanding the transport of nanoparticles in reservoirs. Advances, challenges, and future prospects will be presented.


Farzam Javadpour holds a bachelor’s degree with distinction in petroleum engineering and master’s and PhD degrees in chemical and petroleum engineering, respectively, from the University of Calgary (Canada). He has worked as reservoir engineer in industry and is currently working as a research scientist at the Bureau of Economic Geology (UT-Austin), where he is leading research works on novel techniques of reserve and permeability estimations and liquid and gas flow modeling for shale gas system.

November 19, 2015

Professor Louis Strigari
Texas A&M University
Mitchell Institute for Fundamental Physics and Astronomy
2:30, Thursday, November 19
Farrington Room 105

Galactic Searches for Dark Matter

For nearly a century, more mass has been measured in all types of galaxies than is contained in the visible matter. Through a variety of observations, it has become clear that the dark matter in galaxies is not comprised of known astronomical objects or baryonic matter, and that its identification is certain to reveal a profound connection between astrophysics, cosmology, and fundamental physics. In this talk, I discuss the status of searches for particle dark matter using a variety of different experimental techniques. I conclude by highlighting how in the next several years we will either confirm the leading theoretical model for dark matter, or there will be a paradigm shift in our view of it.

November 2, 2015


The colloquium featuring Adam Reppond of L-3 Communications scheduled for today has been cancelled.

November 2, 2015

Adam Reppond
L-3 Communications
Monday, November 2, 2015
3:00 p.m.
Farrington Room 101

Project Liberty

L-3 is a prime contractor in aerospace systems and national security solutions. L-3 is also a leading provider of a broad range of communication and electronic systems and products used on military and commercial platforms.

Adam is a distinguished alumnus of the SHSU Physics Department.

April 10, 2015

Dr. Tim Noe
Distinguished Alumnus of SHSU
Department of Electrical and Computer Engineering
Rice University
Friday, April 10, 2015
Farrington Room 209

Terahertz Time-Domain Magneto spectroscopy in Pulsed Magnetic Field

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
3:30-4:30 PM
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
Rice University
Department of Physics
Thursday, January 29, 2015
Farrington Room 209
3:00 p.m.

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)
Chicago, Illinois
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
2:00 p.m.

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.

Printable flyer

November 10, 2014

Margaret S. Cheung
University of Houston, Department of Physics; Center for Theoretical Biological Physics, Rice University
Houston, Texas
Monday, November 10, 2014
Farrington Room 209
12:00 p.m.

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
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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