The University of Mississippi
Department of Physics and Astronomy

Seminars/Colloquia, Fall 2017

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, Aug 10
Lewis 101
John Clem
Department of Physics and Astronomy
University of Delaware
NASA Balloon Programs AESOP-lite and ANITA
(PDF)
Tue, Aug 22
Lewis 101
Department Faculty
Department of Physics and Astronomy
University of Mississippi
Introduction to Department Research, followed by Ice Cream Social.(PDF)
Tue, Aug 29
Lewis 101
Mike Reep and Scott Watkins
Department of Physics and Astronomy
University of Mississippi
Machine Shop Physics
Tue, Sep 5
Lewis 101
Vahid Naderyan
Department of Physics and Astronomy
University of Mississippi
MEMS Microphones
Tue, Sep 12
Lewis 101
No Colloquium
 
 
(Graduate Student Comprehensive Examinations)
Tue, Sep 19
Lewis 101
Ron Miles
Department of Mechanical Engineering
State University New York — Binghamton

The Nanophone: Sensing Sound with Nanoscale Spider Silk

Tue, Sep 26
Lewis 101
Farhad Farzbod
Department of Mechanical Engineering
University of Mississippi
Vibrations: from Periodic Structures to the Human Face
Tue, Oct 3
Lewis 101
John Thompson
Department of Physics and Astronomy
University of Maine
Investigating Student Understanding at the Physics-Mathematics Interface
Tue, Oct 10
Lewis 101
Alex Yakovlev
Department of Electrical Engineering
University of Mississippi
Recent Developments on Graphene and Graphene Periodic Surfaces at Microwave and Terahertz Frequencies
Tue, Oct 17
Lewis 101
Marco Cavaglià and Katherine Dooley
Department of Physics and Astronomy
University of Mississippi
2017 Physics Nobel Prize: LIGO
Fri, Oct 20
Lewis 101
Brian Daly
Department of Physics and Astronomy
Vassar College
Picosecond Ultrasonics: Nanoscale Imaging and GHz Surface Acoustic Wave Studies
Tue, Oct 31
Lewis 101
Shaon Ghosh
Center for Gravitation, Cosmology and Astrophysics
University of Wisconsin — Milwaukee
From the Ashes of a Pair of Neutron Stars: The Tale of a Kilonova
Fri, Nov 3
Lewis 101
Matthew Abernathy
Materials Science and Technology Division
U.S. Naval Research Laboratory
Seeing Further with Gravitational Waves and Advanced Optical Coatings
Tue, Nov 7
Lewis 101
Jake Bennett
Department of Physics
Carnegie Mellon University
Prospects for Hadron Spectroscopy at Belle II
Fri, Nov 10
Lewis 101
Chris Moore
Departamento de Fisica
Instituto Superior Técnico — CENTRA, Portugal
The Era of Gravitational Wave Astronomy
Tue, Nov 14
Lewis 101
William E. East
Perimeter Institute for Theoretical Physics, Canada
Uncovering the Dynamics of Spacetime
Thur, Nov 16
Lewis 101
2:45 PM
Leo Stein
Walter Burke Institute for Theoretical Physics
California Institute of Technology
Probing Strong-Field Gravity: Black Holes and Mergers in General Relativity and Beyond
Tue, Nov 21
Lewis 101
Thomas Turkey
Department of Nutrition
Virginia Tech
Continuing Advantages of a Vegetarian Diet
Tue, Nov 28
Lewis 101
Matthias Kaminski
Department of Physics and Aastronomy
University of Alabama
Gauge/Gravitational Holography — Strong Physics far from Equilibrium
Tue, Dec 05
Lewis 101
Final Exam Week  

This page has been viewed 33127 times.
The physics colloquium organizer is Katherine Dooley
This page is maintained by David Sanders
Latest update: Wednesday, 15-Nov-2017 13:00:42 CST

Past semesters: 

Abstracts of Talks


Department Faculty
Department of Physics and Astronomy
University of Mississippi

Introduction to Department Research, followed by Ice Cream Social.

3:00 PM — Society for Physics Students (SPS) greets new undergrads and gives tour of Lewis Hall
3:30 PM — Undergrad / Faculty Pizza Social
4:00 PM — Colloquium: Department Research Overview
4:30 PM — Grad Student / Faculty Ice Cream Social


Mike Reep and Scott Watkins
Department of Physics and Astronomy
University of Mississippi

Machine Shop Physics

Experimental physics depends on instrumentation made in the University of Mississippi's Physics machine shop. Instruments made for Acoustics, Atmospheric physics, Condensed Matter physics, and Particle physics will be shown.


Vahid Naderyan
Department of Physics and Astronomy
University of Mississippi

MEMS Microphones

MEMS (Micro-Electro-Mechanical Systems) microphones are acoustic sensors which translate sound waves to an electrical signal. Recent developments in MEMS technology have led to the development of very small size and high-performance microphones. Silicon fabrication creates the MEMS elements with the geometries of the order of microns. Due to their small size and high performance, MEMS microphones are used in mobile phones, hearing aids, “Internet of Things” devices, small electronic devices, etc. In this talk, I will explain the basic principles of the capacitive MEMS microphones and will talk about the Acoustical, Mechanical, and Electrical domains in a MEMS microphone and their connections.


Ron Miles
Department of Mechanical Engineering
State University New York — Binghamton

The Nanophone: Sensing Sound with Nanoscale Spider Silk

Hundreds of millions of years of evolution resulted in hair-based flow sensors in terrestrial arthropods that stand out among the most sensitive biological sensors known. These tiny sensory hairs can move with a velocity close to that of the surrounding air at frequencies near their mechanical resonance, in spite of the low viscosity and low density of air. No man-made technology to date demonstrates comparable efficiency. Here we show that nanodimensional spider silk captures fluctuating airflow with maximum physical efficiency (Vsilk/Vair ≈1) from 1Hz to 50kHz, providing an unparalleled means for miniaturized flow sensing. Our mathematical model shows excellent agreement with experimental results for silk with various diameters: 500nm, 1.6µm, 3µm. When a fiber is sufficiently thin, it can move with the medium flow perfectly due to the domination of forces applied to it by the medium over those associated with its mechanical properties. By modifying a spider silk to be conductive and transducing its motion using electromagnetic induction, we demonstrate a miniature, directional, broadband, passive, low cost approach to detect airflow with full fidelity over a frequency bandwidth that easily spans the full range of human hearing, as well as other mammals, birds, amphibians, and reptiles.


Farhad Farzbod
Department of Mechanical Engineering
University of Mississippi

Vibrations: from Periodic Structures to the Human Face

This talk covers four different and yet connected subjects; Resonant Ultrasound Spectroscopy (RUS), vibration analysis of periodic structures, and using facial vibrations in wearable computers. RUS is a technique to characterize the elastic and anelastic properties of materials. It is based on the measurements of the vibration eigenmodes of a sample with simple geometry such as a parallelepiped. In Laser RUS, the excitation part is done by a pulsed laser, generating thermoelastically excited ultrasonic pulse. In the detection side, a photorefractive interferometer is used to detect ultrasound. Measured eigenmodes along with eigenfrequencies reveal much information with regard to micro-structural state of the sample material. Novel techniques/problems in laser RUS is discussed in this section. In the second part, periodic structures are discussed. In periodic lattice structures, analysis of wave propagation to uncover dispersion relationships can be greatly simplified by invoking the Floquet-Bloch theorem. The accompanying Bloch formalism, which was first introduced for the study of quantum mechanics and has been borrowed in structural analysis, allows a system's degrees of freedom to be reduced to a small subset contained in a single unit cell. When this is combined with the finite element method, the result is a powerful framework for analyzing wave propagation and dispersion in complex media. In this section, among other things, the manner in which damping affects dispersion is talked about. In the next part, I talk about reciprocity in acoustics and how to break it; one way to break time reversal symmetry is to have a moving wave propagation medium. If the acoustic wave vector and the moving fluid velocity are collinear, we can use the wave vector shift caused by the fluid flow to break reciprocity. An alternative approach we have taken, is to use a fluid velocity field which enters the differential equation of the system as a cross product term with the wave vector. In the final part, bone conduction hearing is discussed; how it helps hearing and how it can be utilized for better communications in wearable technologies.


John Thompson
Department of Physics and Aastronomy
University of Maine

Investigating Student Understanding at the Physics-Mathematics Interface

Because learning physics concepts often requires the ability to construct, interpret, and manipulate mathematical representations and formalism (e.g., equations, graphs, and diagrams), researchers in physics education and mathematics education have been examining how students navigate this interface between mathematics and physics. Our own research into student conceptual understanding of physics has led us to investigate how students use and reason about mathematics, especially calculus, to solve physics problems in several upper-division physics domains. Examples coming from thermal and statistical physics as well as from vector calculus as used in electromagnetism will be given. Instructional materials development and implementation will be discussed.


Alex Yakovlev
Department of Electrical Engineering
University of Mississippi

Recent Developments on Graphene and Graphene Periodic Surfaces at Microwave and Terahertz Frequencies

Graphene, the first 2D material to be practically realized, has attracted great interest in the last decade. The fact that electrons in graphene behave as massless Dirac fermions leads to a variety of anomalous properties, such as charge carriers with ultra-high-mobility and long mean-free paths. Graphene's electrical properties are often represented by a local complex surface conductivity given by the Kubo formula. Since its surface conductivity leads to attractive surface plasmon properties, graphene has become a good candidate for plasmonic applications, especially in the terahertz regime.

In this talk we will briefly discuss electrical, thermal, and mechanical properties of graphene, and will focus on the interaction of electromagnetic waves with graphene and graphene periodic surfaces at microwave and terahertz frequencies. Specifically, we will discuss the enhanced transmission with a graphene-dielectric stack, dual capacitive/inductive nature of graphene periodic surfaces, high-impedance surfaces with graphene patches, excitation of surface plasmon polaritons on graphene, planar hyperlens based on a modulated graphene, subwavelength imaging with graphene loaded wire media, and cloaking with graphene for antenna applications.


Brian Daly
Department of Physics and Astronomy
Vassar College

Picosecond Ultrasonics: Nanoscale Imaging and GHz Surface Acoustic Wave Studies

Ultrafast lasers produce pulses of light that are less than 1 ps in duration, and can be used to generate and detect extremely high frequency ultrasound in the range of about 100 GHz. This technique can be applied to semiconductor metrology (nanometer scale thickness measurements, mechanical properties of thin films, imaging of sub-surface nanostructures) but also provides a window to the fundamental behavior of long-wavelength acoustic phonons that have a significant impact on thermal transport at the nanoscale. In this talk I will review the picosecond ultrasonic measurement technique and discuss recent work to advance nanoscale imaging and the study of surface acoustic waves.


Shaon Ghosh
Center for Gravitation, Cosmology and Astrophysics
University of Wisconsin — Milwaukee<

From the Ashes of a Pair of Neutron Stars: The Tale of a Kilonova

The observation of the binary neutron star coalescence and the resulting electromagnetic counterpart by LIGO & Virgo and the various observing partners around the world has been one of the most amazing discoveries in physics and astronomy in recent times. The multitude of results that were obtained from this discovery, each in their own rights are fascinating. In this talk, I will attempt to condense these results and put them in the context of the efforts that have been carried out for many decades. I will first give a very short history of the subject, then I will talk about the description of the model of the physical process that we thought were responsible for the observed phenomenon. Next, I will talk about the proposed test to verify our model, and how we conducted them. Finally, I will summarize the important results of the multi-messenger observation.


Matthew Abernathy
Materials Science and Technology Division
U.S. Naval Research Laboratory

Seeing Further with Gravitational Waves and Advanced Optical Coatings

The future is here! 100 years after they were first predicted by Einstein, gravitational waves have finally been directly detected. The push is now on to make ever more sensitive detectors capable of seeing further and fainter signals. Such advanced detectors will revolutionize our understanding of the Universe. However, there lurks a surprising limitation to the sensitivity of ground-based gravitational wave detectors that threatens to limit their potential. Within these huge instruments there are optical coatings only microns thick whose thermal motion is large enough to swamp the faintest signals. Therefore, there is a great need for the discovery and development of the next generation of optical coatings free of these effects. This talk will detail how the thermal motion of the coatings can limit the sensitivity of gravitational wave detectors, the improvements made so far, and the future of optical coatings that will allow us to see ever fainter and more distant gravitational wave sources.


Jake Bennett
Department of Physics
Carnegie Mellon University

Prospects for Hadron Spectroscopy at Belle II

The Belle II experiment, currently under construction at the KEK laboratory in Tsukuba, Japan, is the next generation of the highly successful B-factories. A substantial upgrade of both the Belle detector and the KEKB accelerator represent an essentially new experiment. Commissioning of the new SuperKEKB accelerator will start at the end of 2017. Physics running is planned to start in 2018 with a goal of collecting 50 times more data than the first generation B-factories. Belle II is uniquely positioned to make detailed studies of "exotic" hadron states, the so-called XYZ states, that provide the first possibility to explore long-conjectured, nonstandard quarkonium-like states. This talk will give an overview of the detector and accelerator upgrades and describe some of the capabilities of Belle II to explore both conventional and exotic bottomonium and charmonium physics.


Chris Moore
Departamento de Fisica
Instituto Superior Técnico — CENTRA, Portugal

The Era of Gravitational Wave Astronomy

The era of gravitational wave astronomy has begun. The LIGO and Virgo observatories are already revealing the properties of neutron star and stellar mass black hole coalescences. However, many more discoveries await. In the coming years we expect to observe gravitational radiation across a frequency spectrum spanning >10 orders of magnitude, generated by a diverse array of sources from white dwarf stars to supermassive black holes. I will discuss what I consider to be some of the most exciting prospects, and identify several key challenges that must be addressed for these discoveries to be fully utilised in the fields of astronomy, fundamental physics, and cosmology.


William E. East
Perimeter Institute for Theoretical Physics, Canada

Uncovering the Dynamics of Spacetime

With the ground-breaking gravitational wave detections from LIGO/VIRGO, we have entered the era where we can actually observe the action of strongly curved spacetime originally predicted by Einstein. Going hand in hand with this, there has been a renaissance in the theoretical and computational tools we use to understand and interpret the dynamics of gravity and matter in this regime. I will describe some of the rich behavior exhibited by sources of gravitational waves such as the mergers of black holes and neutron stars. I will also discuss some of the open questions, and what these events could teach us, not only about the extremes of gravity, but about the behavior of matter at nuclear densities, the solution of astrophysical mysteries, and even the existence of new particles.


Leo Stein
Walter Burke Institute for Theoretical Physics
California Institute of Technology

Probing Strong-Field Gravity: Black Holes and Mergers in General Relativity and Beyond

General relativity—Einstein's theory of gravitation—has been studied for more than 100 years. Over the past century, we have learned that the theory agrees with all available experimental and observational tests. At the same time we know that the theory is incomplete, as it leads to inconsistencies when coupled with quantum mechanics.

The strong-field regime is our best hope to study GR, both observationally and theoretically, and thus understand how to correct its shortcoming. In this talk, I will discuss investigations in the strong field, including black holes and neutron stars, in GR and theories beyond GR. The main focus will be predicting gravitational waves from merging black holes beyond GR. These predictions will allow for the most rigorous testing of general relativity, using LIGO, in the dynamical strong-field regime.