Seminars and Colloquia, January through June, 2018

• This Week's schedule.
• Earlier Semesters.
• Typical Week's schedule.
• January 1-5, 2018's schedule.
• January 8-12, 2018's schedule.
• January 15-19, 2018's schedule.
• January 22-26, 2018's schedule.
• January 29-February 2, 2018's schedule.
• February 5-9, 2018's schedule.
• February 12-16, 2018's schedule.
• February 19-23, 2018's schedule.
• February 26-March 3, 2018's schedule.
• March 5-9, 2018's schedule.
• March 12-16, 2018's schedule.
• March 19-23, 2018's schedule.
• March 26-30, 2018's schedule.
• April 2-6, 2018's schedule.
• April 9-13, 2018's schedule.
• April 16-20, 2018's schedule.
• April 23-27, 2018's schedule.
• April 30-May 4, 2018's schedule.
• May 7-11, 2018's schedule.
• May 14-18, 2018's schedule.
• May 21-25, 2018's schedule.
• May 28-June 1, 2018's schedule.
• June 4-8, 2018's schedule.
• June 11-15, 2018's schedule.
• June 18-22, 2018's schedule.
• June 25-29, 2018's schedule.

Seminars and Colloquia, Typical Week:

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Physics Colloquium:

Journal Club on Statistical Mechanics and Condensed Matter Physics (Informal):

Oklahoma State Physics Department

Seminars and Colloquia, January 1-5, 2018

No talks scheduled

Oklahoma State Physics Department

Seminars and Colloquia, January 8-12, 2018

No talks scheduled

Oklahoma State Physics Department

Seminars and Colloquia, January 15-19, 2018

Monday, January 15: Martin Luther King Day, University Holiday.

First Week of Classes

Physics Colloquium:

Abstract:

In this talk, I will describe our efforts to understand how light interacts with two 2D systems: graphene and phosphorene. For this purpose, we used several ab initio computational techniques which will be reviewed here. The discovery of graphene ushered the age of 2D materials. The characterization of graphene is usually done with Raman spectroscopy. I will present our theoretical approach to understanding Raman scattering in graphene, and how we can use it to interpret the spectra. The monolayer of black phosphorous (phosphorene), is a semiconducting material that was recently discovered and holds great promise for use in electronic applications. However, phosphorene is not stable and degrades in less than an hour. I will describe how our calculations established the degradation dynamics of phosphorene.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3:00 PM. All students are welcome! Refreshments will be served.

Oklahoma State Physics Department

Seminars and Colloquia, January 22-26, 2018

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Abstract:

Assuming a fertile patch of the string theory landscape leading to a low energy effective theory consisting of the MSSM+hidden sector N=1, d=4 supergravity, we derive probability distributions for Higgs and sparticle masses. These predictions explain why there seems to be a m(weak)−m(susy) Little Hierarchy and why so far no SUSY signal has been seen at LHC. They also provide guidance for future accelerator and dark matter searches.

Finally, they contradict the common misconception that string theory is not predictive.

Physics Colloquium:

Abstract:

Helium is the only element that remains liquid under normal pressure down to zero temperature. Below 2.17K, the bosonic isotope helium-4 undergoes a phase transition to a superfluid. Motivated by this intriguing bulk behavior, the properties of finite-sized helium droplets have been studied extensively over the past 25 years or so. A number of properties of liquid helium-4 droplets are, just as those of nuclei, well described by the liquid drop model. The existence of the extremely fragile helium dimer was proven experimentally in 1994 in diffraction grating experiments. Since then, appreciable effort has gone into creating and characterizing trimers, tetramers and larger clusters. The ground state and excited state of the helium trimer are particularly interesting since these systems are candidates for Efimov states. The existence of Efimov states, which are unique due to scale invariance and an associated limit cycle, was predicted in 1971. However, till recently, Efimov states had—although their existence had been confirmed experimentally—not been imaged directly. Recently, ingenious experimental advances that utilize femtosecond lasers made it possible to directly image the static quantum mechanical density distribution of helium dimers and trimers. I will review some of these experiments and related theoretical calculations that led to the experimental detection of the excited helium trimer Efimov state. Extensions to the time domain will also be discussed. Intriguing laser-kick induced dynamics of the fragile helium dimer is observed experimentally and analyzed theoretically. These initial results open the door for future studies that probe scattering length dominated few-body systems using fast, intense lasers.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3:00 PM. All students are welcome! Refreshments will be served.

Oklahoma State Physics Department

Seminars and Colloquia, January 29-February 2, 2018

Physics Colloquium:

Abstract:

Since 2015, the Large Hadron Collider has produced an unprecedented amount of proton-proton collisions at 13 TeV center-of-mass energy, and many millions of events have been recorded by the ATLAS detector.  One Higgs boson has already been observed, but the possibility remains that it’s part of a larger Higgs Sector.  In this presentation, I will discuss the motivation for and challenges in searching for an additional Higgs boson in the ATLAS Collaboration, an organization that includes physicists from many different cultures.  Though many people from around the world participate in physics research, there is a notable under-representation of women as well as members of several other groups.  The discussion of searches for new particles will be followed by an examination of the current status of diversity in physics, with consideration of steps that can be taken to increase diversity in the field and move toward a more equitable future.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3:00 PM. All students are welcome! Refreshments will be served.

Journal Club on Statistical Mechanics, Condensed Matter Physics, and Optics (Informal):

I will talk about the paper “Physical Content of the Exact Kohn–Sham Orbital Energies: Band Gaps and Derivative Discontinuities,” by J.P. Perdew and M. Levy, Phys. Rev. Lett. 51(20), 1884–1887 (1983).

Oklahoma State Physics Department

Seminars and Colloquia, February 5-9, 2018

Physics Colloquium:

Abstract:

We present development of a nanosecond Q-switched Tm³⁺-doped fiber laser with 16 W average power and 4.4 kW peak power operating at 1940 nm. The laser has a master oscillator power amplifier design, and uses large mode area Tm³⁺-doped fibers as the gain medium. Special techniques are developed to splice Tm³⁺-doped fibers to minimize splice loss. The laser design is optimized to reduce non-linear effects, including modulation instability. Pulse width broadening due to high gain is observed and studied in detail. Medical surgery is a field of application where this laser may be able to improve clinical practice. The laser together with scanning galvanometer mirrors is used to cut precisely around small footprint vessels in tissue phantoms without leaving any visible residual thermal damage. These experiments provide proof-of-principle that this laser has promising potential in the laser surgery application space.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3:00 PM. All students are welcome! Refreshments will be served.

Journal Club on Statistical Mechanics, Condensed Matter Physics, and Optics (Informal):

I will talk about the paper “Replacement manifolds: A method to uniformize semiclassical wave functions,” by J. Vaníček and E.J. Heller, Phys. Rev. E 64, 026215 (2001).

Oklahoma State Physics Department

Seminars and Colloquia, February 12-16, 2018

Physics Colloquium:

Abstract:

The progress of artificial intelligence (AI) technologies has recently been exponential and shown to be both transformative and disruptive in many fields such as computer vision, natural language processing, audio processing, and automobile auto piloting.  AI has become the No. 1 priority for industry leaders like Google, Facebook, Apple, Amazon, Microsoft, and IBM.  AI is expected to have a significant impact on healthcare, especially in the areas of individualized and precision medicine, medical image analysis, disease diagnosis assistance, treatment solution recommendation, care delivery optimization/automation/safety, treatment outcome and toxicity prediction, patient care in resource limited regions, medical error detection and quality assurance, assisted care and chronic disease management with wearable sensors, and surgical and rehabilitation robots.  At UT Southwestern Department of Radiation Oncology medical physicists are working closely with clinicians and biologists to solve various important clinical problems in radiation therapy in specific and medicine in general.  In this talk I will introduce our AI research work at UT Southwestern.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3:00 PM. All students are welcome! Refreshments will be served.

Oklahoma State Physics Department

Seminars and Colloquia, February 19-23, 2018

Journal Club on Statistical Mechanics, Condensed Matter Physics, and Optics (Informal):

Quasiperiodic structures had been studied by mathematicians and even appeared decorating medieval Islamic buildings. However, when in 1982 Dan Shechtman observed a ten-fold scattering pattern from a metal alloy crystal, he was ridiculed by his colleagues who said that his observations contradicted standard texts like Kittel’s. Although initially rejected, Shechtman succeeded in publishing his findings in 1984. For this work he received the 2011 Nobel Prize in Chemistry.

In the talk I shall review several theoretical developments, Shechtman’s findings and some recent technological applications. Finally, I shall show some results for the pentagrid Ising model. [This review has been published leaving out many of the pictures: H. Au-Yang and J.H.H. Perk, Indagationes Mathematicae 24 (2013) 996–1017.]

Oklahoma State Physics Department

Seminars and Colloquia, February 26-March 2, 2018

Physics Colloquium:

Abstract:

In this talk, I will review our recent experimental work on trace gas detection and identification using Raman spectroscopy in nanophotonic waveguides.  The measurements I will describe, with limits of detection in the parts-per-billion range, were made possible using highly-evanescent rib waveguides functionalized with a thin, transparent cladding layer designed to reversibly sorb and concentrate certain classes of chemicals.  In our geometry, over 30% of the mode power resides in the cladding layer and is able to interact with the sorbed analyte.  The concentration enhancement of the sorbent cladding layer, coupled with the fact that the analyte Raman scattering takes place within and along the propagating mode of the waveguide, provides scattering efficiencies enhanced by up to nine orders of magnitude compared to traditional micro-Raman spectroscopy.

Our results have paved the way for a sensitive, miniature, spectroscopy-based trace gas sensor inherently suitable for photonic integrated circuit manufacturing.  I will review the progress of our recent collaboration with the American Institute for Manufacturing (AIM) Photonics foundry to develop and test the components necessary to realize a fully-integrated waveguide-enhanced Raman spectroscopy platform

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3:00 PM. All students are welcome! Refreshments will be served.

Journal Club on Statistical Mechanics, Condensed Matter Physics, and Optics (Informal):

Oklahoma State Physics Department

Seminars and Colloquia, March 5-9, 2018

Week of APS March Meeting

Journal Club on Statistical Mechanics, Condensed Matter Physics, and Optics (Informal):

Oklahoma State Physics Department

Seminars and Colloquia, March 12-16, 2018

Physics Colloquium:

Abstract:

Experiments frequently come with surprises. In this talk, I will describe a serendipitous discovery of Bose fireworks, the sudden emission of many narrow jets of matter waves from Bose–Einstein condensates with oscillating interaction strength. This structure originates from a collective scattering of atoms in the condensate, seeded by quantum fluctuations and amplified by bosonic stimulation. The process is the matter-wave version of superradiance, and results in an intriguing di-jet pattern resembling those observed in high-energy collisions of heavy ions.

Reference: Logan W. Clark, Anita Gaj, Lei Feng, Cheng Chin, Collective emission of matter-wave jets from driven Bose–Einstein condensates, Nature 551, 356 (2017).

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 2:00 PM. All students are welcome! Refreshments will be served.

Oklahoma State Physics Department

Seminars and Colloquia, March 19-23, 2018

Spring Break.

Oklahoma State Physics Department

Seminars and Colloquia, March 26-30, 2018

Physics Colloquium:

Abstract:

The process of crystal growth can be divided into three general classes—ideal growth, surface kinetics-limited growth, and diffusion-limited growth, with diffusion-limited growth being the least understood and the least applied in scientific and industrial ventures (e.g. protein structural analysis, pharmaceutical purification).  In fact, the broader crystal growth community by and large disregards diffusion-limited crystallization because the resulting crystals tend to be heavily branched, defect-ridden, and weaken the integrity of bulk crystals.  Over the past ∼10 years, my group has studied radio frequency (RF) electrochemical crystallization, attaining a basic picture of this diffusion-limited, electrochemical process and developing a number of applications ranging from neural probes to plasmonic materials.  RF electrochemical crystallization occurs on time scales near the minimum of what diffusive transport requires.  Essentially, an RF voltage is applied to an electrode immersed in aqueous salt solution, cycling the electrode potential between +1.0 V and −1.0 V, ∼ 40 million times per second.  During a positive half cycle, metallic ions, such as Au^IIICl₄⁻ for the case of gold crystallization, diffuse to the interface and adsorb onto the electrode surface.  The average inter-ion distance d in a 40.0 mM salt solution is ∼ 3.5 nm, so the electrode must wait approximately d²/2D ∼ 5 ns for an ion to diffuse to its surface, where D is the diffusivity of the ion.  A 40.0 MHz voltage signal has a half cycle duration of 12.5 ns.  Hence, only a few atoms will diffuse to and adsorb onto the electrode surface during such a short half cycle period.  During the subsequent negative half cycle, a fraction of the adsorbed ions are reduced to the crystalline metal (Au⁰), and the crystal grows (slightly).  By varying the amplitude of the RF voltage signal, we control the magnitude of that fraction.  If the amplitude is adjusted so that the growth velocity of the crystal is minimal but positive, many of the historical problems of diffusion-limited crystal growth are overcome.  In this region of parameter space, we have grown branchless, ultra-long, single crystalline gold nanoribbons.  We can also grow millimeter long, 400 nm diameter conducting polymer nanofibers, as well as a number of other kinds of structures.  Applications for these nanowires will be discussed.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3:00 PM. All students are welcome! Refreshments will be served.

Oklahoma State Physics Department

Seminars and Colloquia, April 2-6, 2018

Physics Colloquium:

Abstract:

One of the greatest challenges in computational biophysics is to predict interactions between biological molecules, which play critical roles in biological processes and rational design of therapeutic drugs. Biomolecular interactions involve delicate interplay between multiple interactions, including electrostatic interactions, van der Waals interactions, solvent effect, and conformational entropic effect. Accurate determination of these complex and subtle interactions is challenging. Moreover, a biological molecule such as a protein usually consists of thousands of atoms, and thus occupies a huge conformational space. The large degrees of freedom pose further challenges for accurate prediction of biomolecular interactions.

In my talk, I will present our recent development of physics-based theory and computational modeling on protein-small molecule, protein-protein and protein-RNA interactions. The major strategy is to extract microscopic energetics from the information embedded in the experimentally-determined structures of protein complexes. I will also present applications of the methods to structure-based therapeutic design.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3:00 PM. All students are welcome! Refreshments will be served.

2018 OK-Photovoltaic Research Institute Annual Meeting and Symposium

Saturday, April 7, OSU

Morning Session: Times listed include questions.

• 10:15-11:00 Plenary talk by Dr. Nancy Haegel (NREL)
• 11:00-11:15 Hamidreza Esmaielpour (OU)
• 11:15-11:30 James Sharp (TU)
• 11:30-11:45 Tong Mou (OU)
• 11:45-1:00 LUNCH

Afternoon Session

• 1:00-1:45 Plenary Talk by Dr. Jeremiah McNatt (NASA)
• 1:45-2:00 Rachel Roccanova (OU)
• 2:15-2:30 Kyle Stoltz (OSU)
• 2:30-2:45 Colin R. Brown (OU)
• 2:45-3:15 Coffee break and poster set-up
• 3:15-4:00 Poster session

Further details to follow.

Oklahoma State Physics Department

Seminars and Colloquia, April 9-13, 2018

No talks scheduled

Oklahoma State Physics Department

Seminars and Colloquia, April 16-20, 2018

Physics Colloquium:

Abstract:

The Standard Model of particle physics is highly successful in explaining physics at the fundamental level. However, it does not address some of the observed phenomena, such as, the origin of neutrino mass, dark matter candidate, hierarchies in the fermion masses and mixings, charge quantization and matter-antimatter symmetry of the universe. In this talk, I briefly review the concept of Grand Unified Theories that are attractive candidates to shed light on some of the open questions of the Standard Model.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3:00 PM. All students are welcome! Refreshments will be served.

Oklahoma State Physics Department

Seminars and Colloquia, April 23-27, 2018

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Physics Colloquium:

Abstract:

The study of superfluidity has a long and rich history. Persistent currents are a hallmark of both superfluidity and superconductivity. Just as a current in a superconducting circuit will flow forever, if a current is created in a superfluid Bose-Einstein Condensate, the flow will also not decay. In this talk, I will discuss some of our recent experiments with a superfluid “atom circuit”. Our “atom circuit” is a ring-shaped Bose Einstein condensate. In one set of experiments we have created persistent currents and studied the behavior in the presence of a “weak link” barrier. By tuning the properties of our weak link, created with a focused laser beam, we are able to drive transitions between persistent current states. In a second set of experiments we have studied whether a supersonically expanding ring BEC can be used to model the basic features of an expanding universe. The massive scale of the universe makes the experimental study of cosmological inflation difficult. This has led to an interest in developing analogous systems using table top experiments. In our experiment the ring-shaped BEC serves as the background vacuum and phonons are the analogue to photons in the expanding universe.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3:00 PM. All students are welcome! Refreshments will be served.

Oklahoma State Physics Department

Seminars and Colloquia, April 30-May 4, 2018

Prefinals Week

Joint Physics—Microbiology and Molecular Genetics Colloquium:

Abstract:

No two individual cells ever “look” the same, even if they share the same genes and grow under identical conditions. This unusual phenomenon, frequently referred to as cellular heterogeneity, has been appreciated since the very first microscopy images with subcellular resolution were acquired. However, the ramifications of cellular heterogeneity in life sciences, medicine, and biotechnology have only just started to be understood. In this talk, I will introduce this phenomenon and its origins, and present our recent findings in the context of lipid metabolism and its trade-offs with growth.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3:00 PM. All students are welcome! Refreshments will be served.

Oklahoma State Physics Department

Seminars and Colloquia, May 7-11, 2018

Finals Week

Oklahoma State Physics Department

Seminars and Colloquia, May 14-18, 2018

Joint Chemistry Seminar and Physics Colloquium:

Abstract:

Welcome to this joint OSU Chemistry Seminar and Physics Colloquium! Proteins are the vital players in living cells in health and disease. Biological functions of proteins are carried out via in part chemical reactions and by following the laws of physics. Naturally biophysics is at the interface of physics, chemistry and biology.

My lab is actively developing infrared structural biology, an emerging technology. This is inspired by our research in biological signaling, hofmeister series, biological proton transfer, and intrinsically disordered proteins. All of them share a common bond: protein structural dynamics. Currently it is challenging to capture functionally important structural motions of proteins using widely applied structural biology, namely X-ray crystallography and NMR spectroscopy. In my talk I will introduce time-resolved and temperature resolved infrared structural biology, and most importantly how they enabled us to study biological proton transfer and protein quake in biological signaling and how to study drug binding to heat shock protein 90 for cancer drug development.

Note: Coffee will be served in PS 105 at 3:00 PM.

Oklahoma State Physics Department

Seminars and Colloquia, May 21-25, 2018

No talks scheduled.

Oklahoma State Physics Department

Seminars and Colloquia, May 28-June 1, 2018

No talks scheduled.

Oklahoma State Physics Department

Seminars and Colloquia, June 4-8, 2018

No talks scheduled.

Oklahoma State Physics Department

Seminars and Colloquia, June 11-15, 2018

No talks scheduled.

Oklahoma State Physics Department

Seminars and Colloquia, June 18-22, 2018

No talks scheduled.

Oklahoma State Physics Department

Seminars and Colloquia, June 25-29, 2018

No talks scheduled.

Last Updated: .

This page was prepared by Helen Au-Yang and Jacques H.H. Perk.
jhhp@jperk.phy.okstate.edu