The University of Mississippi
Department of Physics and Astronomy

Seminars/Colloquia, Spring 2015

Unless noted otherwise, Tuesday Colloquia are at 4:00 PM
with refreshments served 15 minutes before each colloquium.

Scheduling for additional seminars will vary.

Date/Place Speaker Title (and link to abstract)
Tue, Jan 20
Lewis 101
 
 
 
Ice Cream Social (PDF)
Tue, Jan 27
Lewis 101
Edward Thomas, Jr.
Physics Department
Auburn University
The Magnetized Dusty Plasma Experiment (MDPX) — First Results
Tue, Feb 3
Lewis 101
Philip W. Phillips
Department of Physics
University of Illinois
Unparticles in Strongly Correlated Electron Matter
Tue, Feb 10
Lewis 101
Michael Strauss
Department of Physics and Astronomy
University of Oklahoma
Measurements of the Properties of a Higgs Boson Using the ATLAS Detector at the LHC (PDF)
Tue, Feb 17
Lewis 101
 
 
 
 
Tue, Feb 24
Lewis 101
Antony Valentini
Department of Physics and Astronomy
Clemson University
Quantum Mechanics and Large-scale Cosmic Anomalies (PDF)
Tue, Mar 3
Lewis 101
Timothy S. Hamilton
Department of Natural Sciences
Shawnee State University
Galaxy Collisions, Black Holes, and Quasars: the Big Picture (PDF)
Tue, Mar 10
Lewis 101
Spring Break  
Tue, Mar 17
Lewis 101
Wanwei Wu, Sumudu Tennakoon and Vahid Naderyan
Department of Physics and Astronomy
University of Mississippi
Wanwei Wu: Λb Baryon Decay: Standard Model or New Physics? (PDF)
Sumudu Tennakoon: Resonant Ultrasound Spectroscopy Study of PMN-PT Relaxor Ferroelectric Material
Vahid Naderyan: How Does Wind Shake the Ground? (PDF)
Tue, Mar 24
Lewis 101
Firouzeh Sabri
Department of Physics
University of Memphis
Experimental Analysis of High Performance Aerogel-polymer Compound Materials for Aerospace and Miomedical Applications
Tue, Mar 31
Lewis 101
 

 
 
Mon, Apr 6
Lewis 109
Atsushi Nishizawa
Division of Physics, Mathematics, and Astronomy
California Institute of Technology
Testing Gravity with Gravitational Waves
(PDF)
Tue, Apr 14
Lewis 101
Jason Raymond
Biomedical Engineering
University of Cincinnati
Lipid-shelled Ultrasound Contrast Agents for Imaging and Therapy: Stable and Unstable Dynamics
Tue, Apr 21
Lewis 101
 
 
 
 
Tue, Apr 28
Lewis 101
Mette Gaarde
Department of Physics and Astronomy
Louisiana State University
Attosecond Science: the Generation and Application of Ultrafast, Coherent XUV Radiation
Tue, May 5
Lewis 101
Final Exam Week  

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Abstracts of Talks


Edward Thomas, Jr.
Physics Department
Auburn University

The Magnetized Dusty Plasma Experiment (MDPX) — First Results

A dusty (or complex) plasma is a four-component plasma system consisting of electrons, ions, neutral atoms, and charged, nanometer to micrometer sized particles (i.e., the "dust"). Because these dust grains are charged, they fully participate in the plasma dynamics and can be used to reveal details about transport, instabilities, and charging properties of plasmas. However, one important area that has not been studied extensively is the area of magnetized dusty plasmas. Even though the charged dust grains in a typical laboratory experiment can acquire several thousand elementary charges, the large mass of the grains ensures that the charge-to-mass ratio is quite low. As a result, it is technically challenging to design an experiment that can achieve full magnetization of ions, electrons, and the charged dust grains. This presentation will provide an overview of the development of magnetized dusty plasma experiments and highlight initial results from the MDPX facility.


Philip W. Phillips
Department of Physics
University of Illinois

Unparticles in Strongly Correlated Electron Matter

Solid state physicists are in love with electrons, in no small part because magnetism and conduction are explained by them in a wide class of materials. However, high-temperature superconductivity has resisted solution in terms of the standard paradigm as a result of the strong interactions. I begin this talk by asking a simple question: can all the charge density in the basic model for high-temperature superconductors be exhausted by counting all the electrons in the sample. I show that the answer is no. I propose instead that the unparticle construct of Howard Georgi's makes up the difference. Unparticle stuff is scale invariant matter that should be thought of as having all possible mass. I will show how a gravity construction can be used to model unparticles. I will close by demonstrating that the superconducting instability of unparticles is quite unconventional and likely to be operative in high-temperature superconductors.


Michael Strauss
Department of Physics and Astronomy
University of Oklahoma

Measurements of the Properties of a Higgs Boson Using the ATLAS Detector at the LHC

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. Searches for additional Higgs Bosons may also be discussed.


Antony Valentini
Department of Physics and Astronomy
Clemson University

Quantum Mechanics and Large-scale Cosmic Anomalies

Recent observations by the Planck satellite point to the existence of large-scale anomalies in the cosmic microwave background (CMB). We discuss how these might be explained in terms of the de Broglie-Bohm formulation of quantum mechanics, according to which quantum fluctuations arise from a dynamical process of relaxation to equilibrium. An analysis of the de Broglie-Bohm dynamics on expanding space shows that relaxation is generally retarded for long-wavelength field modes. We may then expect a large-scale power deficit in the CMB, as appears to be observed. It is shown by numerical simulations that the deficit in the power spectrum (emerging from a pre-inflationary era) will have a characteristic shape, which we are currently searching for in the data. We also discuss how our scenario might explain the observed large-scale violations of statistical isotropy.


Timothy S. Hamilton
Department of Natural Sciences
Shawnee State University

Galaxy Collisions, Black Holes, and Quasars: the Big Picture

Quasars and other “active galaxies” are only a brief phase in the life of otherwise normal galaxies. Over the past fifty years, we have learned much about what powers them and about the galaxies in which they live. But recent work predicts that perhaps 80% of quasars are hidden, shrouded in the dust of galaxy collisions. At the same time, other studies claim that only the very brightest of these involve collisions at all. Our biggest challenges now are to uncover this hidden population and to test how galaxy mergers play a role in triggering the most powerful continuous sources of light in the universe.


Wanwei Wu
Department of Physics and Astronomy
University of Mississippi

Λb Baryon Decay: Standard Model or New Physics?

Heavy quark decays provide a very advantageous investigation to test the Standard Model (SM). We calculate the decay rate of Λb to Λc, tau lepton and a relevant antineutrino in the SM and with New Physics, which provides theoretical predictions to the physics beyond the SM.


Sumudu Tennakoon
Department of Physics and Astronomy
University of Mississippi

Resonant Ultrasound Spectroscopy Study of PMN-PT Relaxor Ferroelectric Material

Lead magnesium niobate-lead titanate (PMN-PT) is a perovskite relaxor ferroelectric material exhibiting superior electromechanical properties compared to the conventional piezoelectric materials. In this talk I will be discussing the results from our recent experiments on investigating temperature and pressure effects on elastic properties of unpoled single crystal PMN-PT material with the chemical composition near the morphotropic phase boundary (MPB). The temperature range we explored was from 293 K to 873 K (20°C to 500°C) and the pressure range was from near vacuum to 500 PSI (3.45 MPa).


Vahid Naderyan
Department of Physics and Astronomy
University of Mississippi

How Does Wind Shake the Ground?

Wind noise at low frequency is a problem in seismic surveys which reduces seismic image clarity. In order to understand the coupling phenomenon quantitatively, we investigated the driving pressure perturbations on the ground surface associated with wind-induced ground motions. We deployed multiple triaxial geophones at a flat site under windy conditions at different depths to study the induced ground displacement. I will discuss the important results of the measurements and will compare the prediction to the measurement results.


Firouzeh Sabri
Department of Physics
University of Memphis

Experimental Analysis of High Performance Aerogel-polymer Compound Materials for Aerospace and Miomedical Applications

Aerogels are mesoporous light-weight solids with tunable bulk and surface properties that offer superior thermal insulation capabilities, attributed to the highly tortuous nature of the interconnecting porous network. While aerogels have been explored extensively for thermal insulation applications, the high surface to volume ratio of this class of materials also provides numerous anchoring sites for attachment of cells which makes aerogels a suitable platform for tissue engineering and potential biomedical applications. The versatile nature of aerogel preparation offers unique opportunities for surface and bulk doping that allows for the design of advanced functional materials with targeted physical and chemical properties. The work presented will summarise recent efforts in design and development of “smart” materials and fundamental understanding of materials under varying environmental conditions. Thermal and mechanical characterization tools were implemented in order to characterize the effects of additives and dopants on bulk material properties.


Atsushi Nishizawa
Division of Physics, Mathematics, and Astronomy
California Institute of Technology

Testing Gravity with Gravitational Waves

General Relativity is a modern theory of gravity and has passed various observational tests so far. However, almost all tests have been limited to the weak regime of gravity in a static system. In the coming years, it is expected that the next-generation gravitational wave detectors will detect gravitational waves from compact binaries or supernovae, and enable us to probe for strong and dynamical aspects of gravity. Then how do we test gravity with gravitational waves? How sensitive are they? What can we learn from the tests? In this presentation, I will focus on model-independent tests of gravity, in particular, the polarization test and the propagation speed test. With these tests, the properties of gravitational waves and gravity theories can be constrained in a generic way. I will also talk about future prospects of these tests.


Jason Raymond
Biomedical Engineering
University of Cincinnati

Lipid-shelled Ultrasound Contrast Agents for Imaging and Therapy: Stable and Unstable Dynamics

Lipid-shelled ultrasound contrast agents known as “echogenic liposomes” are nanoparticle theragnostic agents being developed to target and treat cardiovascular disease. This talk will present recent results using an ultra-high-speed optical imaging approach to investigate the acoustic response of these agents. The investigations utilize an ultra high-speed imaging system (“Brandaris 128”, Rotterdam, the Netherlands) which was developed for imaging physical phenomena such as ultrasound-microbubble interaction at up to 20 million frames per second. Results of two studies using this unique imaging facility will be presented. In the first study, we demonstrate a method to estimate the acousto-mechanical properties based on the impulse response. In the second study, we investigate the response to multiple-cycle acoustic pulses, which result in loss of gas from individual particles. These studies demonstrate that acoustically-active or “echogenic” liposomes can be considered a theragnostic agent, with both stable and unstable dynamics that can be exploited using different ultrasound parameter regimes.


Mette Gaarde
Department of Physics and Astronomy
Louisiana State University

Attosecond Science: the Generation and Application of Ultrafast, Coherent XUV Radiation

The time resolution of an ultrafast process requires access to an even faster light source and/or detector. The natural timescale for the dynamics of bound electrons is about 100 attoseconds, or one tenth of a femtosecond. Attosecond science explores the ability to resolve this electron dynamics, both in the generation and application of attosecond pulses. I will give an introduction to how attosecond pulses are produced, in the interaction between an intense, ultrafast laser field and a gas of atoms. I will also present a number of applications of attosecond science, in attosecond transient absorption, ultrafast laser filamentation, and XUV frequency combs.