Seminars and Colloquia, July through December, 2011

• This Week's schedule.
• Earlier Semesters.
• Typical Week's schedule.
• July 4-8, 2011's schedule.
• July 11-15, 2011's schedule.
• July 18-25, 2011's schedule.
• July 25-29, 2011's schedule.
• August 1-5, 2011's schedule.
• August 8-12, 2011's schedule.
• August 15-19, 2011's schedule.
• August 22-26, 2011's schedule.
• August 29-September 2, 2011's schedule.
• September 5-9, 2011's schedule.
• September 12-16, 2011's schedule.
• September 19-23, 2011's schedule.
• September 26-30, 2011's schedule.
• October 3-7, 2011's schedule.
• October 10-14, 2011's schedule.
• October 17-21, 2011's schedule.
• October 24-28, 2011's schedule.
• October 31-November 4, 2011's schedule.
• November 7-11, 2011's schedule.
• November 14-18, 2011's schedule.
• November 21-25, 2011's schedule.
• November 28-December 2, 2011's schedule.
• December 5-9, 2011's schedule.
• December 12-16, 2011's schedule.
• December 19-23, 2011's schedule.
• December 26-30, 2011's schedule.

Seminars and Colloquia, Typical Week:

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Physics Colloquium:

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

Oklahoma State Physics Department

Seminars and Colloquia, July 4-8, 2011

No talks scheduled.

Oklahoma State Physics Department

Seminars and Colloquia, July 11-15, 2011

No talks scheduled.

Oklahoma State Physics Department

Seminars and Colloquia, July 18-22, 2011

High Energy Physics Seminar:

Oklahoma State Physics Department

Seminars and Colloquia, July 25-29, 2011

High Energy Physics Seminar:

Abstract:

One of the most important problems in elementary particle physics is the so called flavor problem. It means: Why do weak isospin partner masses split? Why quarks and leptons have diferent masses? Why is there a mass hierarchy between generations? Presently we know that neutrino oscillation data are well described by massive neutrinos which makes the flavor problem even more interesting: Why is there a mixing angle hierarchy in the quark sector but not in the lepton sector? Most, if not all, of the solutions proposed until now demand a rich scalar sector. In fact, in the context of the standard model nothing limits the number of the scalar multiplets. In this talk we show how the A₄ discrete symmetry could solve the flavor problem when we consider an extended scalar sector in relation to the standard model. The outline of the talk is first (1) we will present the model, (2) we discuss in some detail the results obtained for the masses and mixing, (3) the simplifications that A₄ made in the scalar sector, and finally (4) some discussions.

Oklahoma State Physics Department

Seminars and Colloquia, August 1-5, 2011

No talks scheduled.

Oklahoma State Physics Department

Seminars and Colloquia, August 8-12, 2011

No talks scheduled.

Oklahoma State Physics Department

Seminars and Colloquia, August 15-19, 2011

No talks scheduled

Oklahoma State Physics Department

Seminars and Colloquia, August 22-26, 2011

First Week of Classes

No talks scheduled.

Oklahoma State Physics Department

Seminars and Colloquia, August 29-September 2, 2011

Second Week of Classes

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Oklahoma State Physics Department

Seminars and Colloquia, September 5-9, 2011

Labor Day Break: Monday, September 5

Physics Colloquium:

Abstract:

Modern quantum and atom-optical experiments allow for an unprecedented control of microscopic degrees of freedom, not just in the initialization but also in the dynamical evolution of quantum states. This talk focuses on the dynamics of ultracold bosons in optical lattice structures. As a paradigm, we report on experimental as well as theoretical results on the interband transport in a tilted lattice, i.e., a realization of the famous Wannier–Stark problem. An extended Bose–Hubbard model is presented for two coupled energy bands. For reasonable lattice sizes, this model gives access to the full quantum spectrum, which allows us a good characterization of “horizontal” (spatially) and “vertical” (energetic) quantum transport. For specific parameters, resonant tunnelling between the bands can be exploited to map the original model onto a much simpler effective spin Hamiltonian. General perspectives on future directions of our study of strongly correlated bosons in lattice structures conclude the talk.

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 High Energy Physics Seminar on Talk-Back Television:

Oklahoma State Physics Department

Seminars and Colloquia, September 12-16, 2011

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Physics Colloquium:

Abstract:

It all started to unravel, when I bought the Smartpen.  I wanted to monitor student writing from the front of the lecture hall, to bring up selected student work for view by the whole class, and to discuss and comment on that work.  My best shot, the Smartpen, proved too cumbersome.  But I could talk, while I wrote out my lectures, and with a click of the mouse publish a PDF file.  By clicking the red dot anywhere on the lecture, the student can hear what I’m saying and see what I am writing at that point in the lecture.  “Skipping ahead” or “go over and over a certain part” is under student control.  Why lecture?  But with 270 students in a room, what can you do?  Interestingly, to appease the Honors College, the department chairman put all honors students in one recitation promising the instructor, not a TA, would teach it as an overload.  So, I must meet weekly with 18 – 20 honors students.  What if they worked a week ahead?  They can work, learn and argue the material to be used in next week’s “lectures.” Then these students can be positioned around the room to hand out questions to smaller groups of 10 – 14 students, to encourage and guide discussion, and to answer questions. Four TAs and I will back them up.  Clearly the physics training should be enhanced for the honors students.  Furthermore, if we grouped students according to recitation section, then the same students meet as a group four times a week.  Think what that means for the freshman who is “lost in the crowd” or the student repeating the course, or for just having the odd question answer by friends.  And we know groups are smarter than the smartest person.  Why nickel and dime students with grades, when we want them to take charge of their own learning? Homework should be assigned and due and along with weekly quizzes graded.  But the grades are formative, indicating what is mastered, what isn’t, how to improve, and not counted as part of the final grade.  Exams determine the class grade and are weighted more at the end.  So there is no point cheating on homework.  The only reason to do homework is to learn the material.

The interactions in my first honors recitation were so intense, students lost track of time.  I had to kick them out of the classroom.  Fun already!

“It’s with regret I tell you I had to drop the honors section of physics. It was a complication of my hours as well as workload with other classes and my extra-curricular activities. Do not fret though, I am still excited to learn to be a Newtonian thinker!”

“Dr. Ackerson, What happened (failure) was definitely the lost in the crowd syndrome.  It was just one lecture after another with really no time to help with the tiny little details, which I understand has to happen on an individual basis.  … And I have to say I am LOVING the breaking into sections idea over the massive crowd.  As well as, the not really having homework (graded for a grade).  It reinforces the actual learning of the course for personal reasons instead of breaking everything that I try down into points.  That just seemed to depress me.  Can't wait for class!!

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, September 19-23, 2011

Physics Colloquium:

Abstract:

THz photonics will be reviewed, starting with the use of photo-conductive switching on lithographically fabricated transmission lines on semiconductor chips to the development of a complete optoelectronic THz-TDS system. THz waveguide measurements show that THz phenomena can be considered as micro-microwaves. The performance of microwave antennas and THz quasi-optics will be directly compared. New “world-record” THz long-path (167 m) phase coherent measurements of the atmosphere, which have revealed the ideal THz bit pulse, will be presented. Future opportunities in fundamental research and practical applications, including THz communications, will be described.

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, September 26-30, 2011

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Physics Colloquium:

Abstract:

Do you use the library? — How?

• We will spotlight library services and databases useful in the Physics field.  (Presented by Kiem Ta, Science & Engineering Division)

• Endnote/Endnote Web: What is it and how it can help!   (Presented by Nicole Sump-Crethar, Digital Library Services)

• Journal Budget, Book Budget and Library Services.   (Questions answered by Richard Paustenbaugh, Associate Dean of Libraries for Research and Instruction Services)

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):

Abstract:

Quantum entanglement plays a fundamental role in Quantum Optics and Quantum Information Theory. The property of entanglement is a nonclassical correlation between the parties of a compound quantum system which cannot be described by classical joint probability distributions. We present new approaches for the identification of entanglement. For this identification we have derived separability eigenvalue equations. From the solution of these equations, we obtain necessary and sufficient entanglement tests, and optimized quasiprobability distribution of entanglement. The negativities of the latter allow us to conclude that no classical probability can generate the considered state. For the quantification of entanglement, we determine the Schmidt number—the number of global superpositions—of quantum states. We also consider misleading results from distance based measures for the amount of entanglement for two entangled states.

Oklahoma State Physics Department

Seminars and Colloquia, October 3-7, 2011

Physics Colloquium:

Abstract:

The OSU Radiation Physics Laboratory is involved in a variety of research projects in areas including medical physics, space radiation protection and dosimetry, and lightning initiation. In medical physics we a are collaborating with the ProCure proton treatment center in Oklahoma City to determine the contribution from secondary neutrons to dose outside the treatment volume received by patients undergoing proton cancer treatment. In space radiation protection and dosimetry, we are developing a tissue equivalent proportional counter to measure radiation dose received by astronauts during space flight and to characterize the space radiation environment both temporally and spatially. Our latest project, in collaboration with researchers in the OU Department of Meteorology, is to investigate the role of cosmic ray extensive air showers in the initiation of the lightning discharge during thunderstorms. An overview of these and other research activities in the our lab will be presented.

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, October 10-14, 2011

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

Abstract:

Multi-photon interferences with indistinguishable photons emitted by independent light sources are at the focus of current research owing to their potential in optical quantum computing, creating remote entanglement for quantum computation and communication and quantum metrology. Using single photon detection modules we performed multi-photon interferences up to fifth order between photons emitted by independent thermal and coherent light sources (TLS, CLS) and compare the corresponding multi-photon signals to those generated by single photon emitters (SPE). It will be shown that all measurements of coherent and thermal light fields can be also done using a commercial CCD camera. This technique dramatically simplifies the experimental setup and enables a wide range of new higher-order correlation measurements.

Physics Colloquium:

Abstract:

This presentation will focus on classical molecular dynamics (MD) simulations of nanoscale behavior in two distinct material systems.  First, MD simulations of plastic deformation in nanocrystalline (NC) Cu with small amounts of antimony (0.0-2.0 at.%Sb) segregated to the grain boundaries will be presented.  Cu is modeled using an embedded-atom method interatomic potential which has been calibrated to match intrinsic and unstable stacking fault energies in Cu.  In NC models, MD simulations show that Sb coverage on the grain boundaries can stabilize the nanocrystalline microstructure in qualitative agreement with TEM images from experiments on ultra-fine grained samples.  During tensile deformation, MD simulations show that Sb positioned at the grain boundaries increases the flow strength of NC Cu but does not shift the grain diameter associated with this maximum flow strength.  Second, MD simulations of diffusion of small atmospheric penetrants (O₂ and N₂) in polydimethylsiloxane (PDMS) based nanocomposites with metallic nanoparticle inclusions will be presented.  PDMS is modeled within the MD framework using a hybrid coarse-grained interatomic potential which retains atomic distinction along the siloxane backbone but models the methyl side groups as united atoms.  Diffusion coefficients for O₂ and N₂ penetrants are extracted using molecular dynamics simulations, for a range of temperatures and nanoparticle volume fractions.  It is found that the Williams–Landel–Ferry equation provides a satisfactory description of the role of temperature on diffusion, with coefficients influenced by the nanoparticle volume fraction.

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.

Fall Break: Friday, October 14

Oklahoma State Physics Department

Seminars and Colloquia, October 17-21, 2011

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Joint Physics & Chemistry Colloquium:

Abstract:

A set of new computational methods has been developed for simulating, refining, and modeling supermolecular complexes at multiple scales.

We have developed a quantized elastic deformational model (QEDM) to reliably describe large-scale protein motions in the absence of amino-acid sequence and atomic coordinates. QEDM yields an accurate description of protein dynamics over a wide range of resolutions even as low as 30 Å. We also report a novel X-ray crystallographic refinement protocol for modeling anisotropic thermal parameters of supramolecular complexes and membrane proteins. With this protocol, a very small set of low-frequency normal modes (e.g., 25 ∼ 50 modes) can be used to reconstruct molecular thermal motions and their contributions to X-ray diffraction. The method was applied to a set of supramolecular complexes and membrane proteins whose structures were all solved at moderate resolutions, typically 3 ∼ 4 Å. The results universally show that the R_free of the models refined with normal modes were lower than the original conventionally-refined models. In addition, the distribution of anisotropic thermal ellipsoids revealed structural flexibility related to protein function. Most importantly, the refinement improved the electron density maps, allowing for placement of a substantial number of missing atoms. In the case of ion channel Kv1.2, for example, we were able to rebuild missing atoms constituting roughly a third of the total molecular mass. These new protocols will significantly improve the structures of many highly flexible supramolecular complexes and membrane proteins, which are otherwise beyond the reach of any currently available methods. Furthermore, the data of those flexible systems are becoming ever more abundant, which makes the new refinement methods timely and valuable tools.

On the enhanced sampling of biomolecular simulation, we report a single-copy tempering method for simulating large complex systems. In a generalized ensemble, the method uses runtime estimate of the thermal average energy computed from a novel integral identity to guide a continuous temperature-space random walk. We first validated the method in a two-dimensional Ising model and a Lennard–Jones liquid system. It was then applied to folding of three small proteins, trpzip2, trp-cage, and villin headpiece in explicit solvent. Within 0.5 ∼ 1 microsecond, all three systems were folded into atomic accuracy: the alpha carbon root mean square deviations of the best folded conformations from the native states were 0.2, 0.4, and 0.4 Å, for trpzip2, trp-cage, and villin headpiece, respectively. Results of folding of larger proteins will also 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, October 24-28, 2011

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Physics Colloquium:

Abstract:

Although the quantum nature of light has been discovered over a century ago, controlling its quantum states still presents a considerable technical challenge. The past decade has shown significant progress in solving it. We are learning to produce and measure arbitrary quantum optical states, save them in memory cells and even bring them into interaction with each other. Mastering these abilities is paramount for further development of quantum information technology.

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, October 31-November 4, 2011

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Abstract:

Recently a challenging result has been announced by OPERA collaboration, which states that muon neutrinos travel with a velocity greater than the speed of light in vacuum. In this talk I shall discuss the challenges posed by this result, its possible solutions, and phenomenological constraints that provides serious objections to most of the theoretical explanations.

Physics Colloquium:

Abstract:

We argue that the standard model of particle physics cannot explain the existence of the visible matter, dark matter and dark energy. We need to extend the standard model by violating both the Baryon (B) and Lepton (L) numbers. We then discuss some of the generic B and L violating models to explain both the visible and the dark sectors of the universe, giving emphasis to the experiments and testable features of these models.

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, November 7-11, 2011

Physics Colloquium:

Abstract:

We develop and apply state-of-the-art quantum computational methods to study the physics of materials. The electronic structure of many of the oxides containing d- and f-elements has long been a challenge for theory. For example, the traditional workhorses of density functional theory, the local density approximation (LDA) and the generalized gradient approximations (GGA), predict most of these systems to be metallic, when in fact they are insulators with band gaps of several eV. These problems reflect the localization/delocalization dilemma faced in systems with weak overlap and seem to be largely overcome by the new generation of hybrid density functionals developed for molecular studies. Only fairly recently has it been possible to apply these functionals to solids but in the cases studied thus far we find a distinct improvement when comparing with experiment. Hybrid functionals have also made a counterintuitive prediction: that of significant covalency in PuO₂, as opposed to UO₂; a prediction that has now been addressed by experiment. I will review predictions of the theory and recent experimental work on the first single-crystal quality samples of PuO₂.

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, November 14-18, 2011

Physics Colloquium:

Abstract:

Discretizing light behavior requires optical elements that can confine optical energy at distinct sites. As indicated in several studies discrete systems like optical arrays and cavity lattices open up new directions in terms of modifying light transport properties in both the linear and nonlinear regime. One such example is that of discrete solitons resulting from the interplay between lattice diffraction and material nonlinearity. In optics, this class of self-localized states has been successfully observed in both one- and two-dimensional nonlinear waveguide arrays. New developments in laser “writing” now allow the realization of all-optical discrete switching networks in fully 3D environments. In this talk we provide an overview of recent theoretical and experimental developments in this field. These include spatio-temporal interactions, X-wave formation, as well as experimental observations of Anderson localization in such systems. The possibility of realizing PT-synthetic photonic lattices will be also discussed. Finally, results pertaining to linear propagation and revivals as well as quantum dynamics of entangled photons in lattices will be presented.

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):

Abstract:

Carbon based nano-materials such as carbon nanotubes (CNTs) and graphene are promising for nanoscale applications due to their tunable electronic and thermal properties. These are excellent low-dimensional systems (1D and 2D) that have phonon mean free paths exceeding a micrometer in length. Coherent thermal transport in these systems can be well described by the Landauer formalism in which the transport is determined by the transmission probabilities of phonons between thermal reservoirs. In this context, the theories that were used initially in calculating electronic transmission probabilities should be applicable to phonons. One example is the recent use of the Green’s function approach. We have adapted R-matrix theory to calculate phonon scattering across systems of molecular to mesoscopic scale. Molecular dynamics(MD) simulation is also an essential tool in nanoscale thermal transport. We study the strain effect on the thermal transport in graphene nanoribbons using molecular dynamics simulations. Moreover, we demonstrate how the thermal rectification is achieved by engineering the strain on a rectangular graphene nanoribbon.

Oklahoma State Physics Department

Seminars and Colloquia, November 21-25, 2011

Thanksgiving Break: November 23-25

Oklahoma State Physics Department

Seminars and Colloquia, November 28-December 2, 2011

No talks scheduled

Oklahoma State Physics Department

Seminars and Colloquia, December 5-9, 2011

Prefinals Week

No talks scheduled

Oklahoma State Physics Department

Seminars and Colloquia, December 12-16, 2011

Finals Week

No talks scheduled

Oklahoma State Physics Department

Seminars and Colloquia, December 19-23, 2011

No talks scheduled

Oklahoma State Physics Department

Seminars and Colloquia, December 26-30, 2011

No talks scheduled

Last Updated: November 28, 2011.

This page was prepared by Helen Au-Yang and Jacques H.H. Perk.