Events

Ken Bader
Department of Internal Medicine
University of Cincinnati

Mechanical Ablation of Tissue with Focused Ultrasound

Histotripsy is a transcutaneous focused ultrasound therapy that ablates tissue through the mechanical oscillations of microbubbles, or cavitation. Preclinical studies have found histotripsy effective for the treatment of prostate pathologies, cancer, deep vein thrombosis, and congenital heart disease. In this talk, the forms of histotripsy and their ablative mechanisms will be modeled in silico, and image-guidance techniques for mechanical ablation will be discussed. An analytic model will be presented to predict the extent of the treatment zone. This analytic model can be used for treatment planning, and to aid the FDA in the development of regulatory standards for histotripsy. Image-guidance of histotripsy will be demonstrated with a new ultrasound imaging modality called passive cavitation imaging (PCI). Studies in a prostate phantom demonstrate that PCI correlates well with the width of the ablation zone, indicating PCI can be used as a predictive metricfor tissue ablation from histotripsy. Finally, PCI will be used to monitor cavitation when histotripsy is used in combination with a lytic agent to lyse clots in a model of deep vein thrombosis. A significant improvement was observed in the thrombolytic efficacy for the combination treatment over histotripsy alone, suggesting a synergistic effect between histotripsy and the lytic agent.

Thomas Sotiriou
School of Physics & Astronomy
University of Nottingham

Black Holes Without Relativity

Lorentz symmetry is central to the concept of a black hole, as it precludes superluminal motion. It is not obvious that one can even define what a black hole is if Lorentz symmetry is abandoned, so one might expect that any observational evidence supporting the existence of black holes will impose very stringent constraints on Lorentz violations. I will discuss some basic aspects of causality in theories that violate Lorentz symmetry and I will argue that, remarkably, the concept of a black hole survives in these theories. After defining the appropriate notion of black hole, I will explore their basic aspects and discuss how they differ from black holes in General Relativity.

Richard Brito
Gravitation in Técnico
Instituto Superior Técnico — CENTRA

Interaction Between Bosonic Fields and Compact Objects

Fundamental bosonic fields generically arise as possible dark matter candidates and in extensions of General Relativity, but are also a useful proxy for more complex interactions. In this talk I will discuss the rich phenomenology of fundamental bosonic fields around black holes and compact stars. In particular I will discuss: (i) the interaction of self-gravitating bosonic structures with compact stars; (ii) superradiant instabilities around black holes and how it can be used to constrain particle masses.

Pengfei Zhang
Department of Mathematics
University of Mississippi

Homoclinic Intersections for Geodesic Flows on Convex Spheres

Transverse homoclinic intersection was discovered by Poincare in the study of stability properties of periodic orbits of n-body problem. Poincare realized that this is a mechanism which not only destroys the stability of periodic orbits but also leads the existence of chaos in the phase space.

In this talk, we will study the geodesic flows on convex spheres. We show that, generically, every closed geodesic is either hyperbolic or irrationally elliptic. Moreover, every hyperbolic closed geodesic admits some transverse homoclinic intersection. Therefore, (everywhere) chaotic dynamics can happen generically on manifolds with simple/trivial topology.

Greg Dooley
Kavli Institute for Astrophysics and Space Research
Massachusetts Institute of Technology

Tidal Stripping with Self-Interacting Dark Matter

Self-interacting dark matter (SIDM) postulates that dark matter is not entirely collisionless, but self scatters at a low rate. By transforming dark matter halo cusps to cores, SIDM offers a solution to the “too big to fail” problem and cusp/core problem in the Milky Way and local field. Two classes of models exist, with velocity-independent and velocity-dependent cross sections. While tight constraints exist on velocity-independent models, constraining velocity-dependent models remain elusive. In this talk, I discuss the implications of both types of SIDM on the tidal disruption of satellite galaxies in a Milky Way-like host. While the total dark matter mass loss rate is not affected, stellar mass loss is enhanced due to lower binding energy in subhalo cores. I discuss the variables affecting the strength of the increased stellar mass loss rate, the effect on observables in the Milky Way, and where we need to look to further constrain or identify self-interacting dark matter.

Alexander B. Yakovlev
Department of Electrical Engineering
University of Mississippi

Non-local Susceptibility of the Wire Medium in the Spatial Domain Considering Material Boundaries

The interaction of electromagnetic waves and wire media has been of interest for many years, driven by applications utilizing artificial plasma, epsilon-near-zero materials, negative refraction, wave canalization and other uses. When the period of the wires is small compared to wavelength, the structure can be considered as a homogeneous (homogenized) medium. Early models of wire media neglected spatial dispersion of the homogenized material, but it has more recently been shown that non-local effects are verystrong for wire media and often cannot be ignored.

In this work, we show that the non-local susceptibility for a nontranslationally invariant homogenized wire medium is, modulo a constant, given by a simple Green's function related to the material geometry. We also show that two previous methods for solving wave interaction problems for bounded wire media (wave expansion method and transport equation) are equivalent to each other, and to a third method involving particle reflection at the boundary. We discuss the importance of the dead layer or virtual interface, and find it to be analogous to the excitonic semiconductor case. Several examples are provided to clarify the material.

Ahmed Rashed
Department of Physics and Astronomy
University of Mississippi

Non-standard Tau Neutrino Interactions

We now know that neutrinos have masses and that there is a leptonic mixing matrix just as there is a quark mixing matrix. The existence of neutrino masses and mixing requires physics beyond the standard model (SM). Hence, it is not unexpected that neutrinos could have new interactions beyond the standard model, or non-standard interactions (NSI). The effects of NSI have been widely considered in neutrino phenomenology. Bounds have been set on the NSI parameters. I will discuss the impact of the NSI on the measurement of neutrino mixing parameters such as the atmospheric and reactor mixing angles, mass hierarchy, and CP violation. We include form factor effects in our calculations and find the deviation of the actual mixing angle from the measured one, assuming the standard model cross section, can be significant and can depend on the energy of the neutrino.

A key property of the SM gauge interactions is that they are lepton flavor universal. Evidence for violation of this property would be a clear sign of new physics (NP) beyond the SM. Recently, hints of lepton flavor non-universality emerged from B-meson decay channels observed in the BaBar and LHCb experiments. We proposed tests of lepton flavor non-universality in tau-neutrino scattering. Different models have been introduced in this study of which charged Higgs, W', and Leptoquark.

Ice Cream Social

Michael S Turner
Kavli Institute for Cosmological Physics
University of Chicago

The Big Picture:  What We Know About How the Universe Began and What We Are Trying to Find Out

Today the Universe is made out of dark matter, dark energy and a small amount of ordinary matter (the atoms we are made of).  We can trace the history of the Universe back to when it was a microsecond and was a formless quark soup.  We now have good evidence for an early burst of tremendous expansion (inflation) that stretched sub-atomic quantum fluctuations to astrophysical size and created the seeds for galaxies.  But there is much to figure out, including what dark matter is made of, what the nature of the mysterious dark energy is, and when inflation took place.

Don Summers et al.
Department of Physics and Astronomy
University of Mississippi

Fascinating Physics Demonstrations

Fifty minutes of fascinating physics demonstrations, including milk jug rockets, will be presented.

Don Summers Presenting
Department of Physics and Astronomy
University of Mississippi

Powers of Ten

Powers of Ten illustrates the universe as an arena of both continuity and change, of everyday picnics and cosmic mystery. It begins with a close-up shot of a man sleeping near the lakeside in Chicago, viewed from one meter away. The landscape steadily moves out until it reveals the edge of the known universe. Then, at a rate of 10-to-the-tenth meters per second, the film takes us towards Earth again, continuing back to the sleeping man's hand and eventually down to the level of a carbon atom.

Chandrima Chatterjee
Department of Physics and Astronomy
University of Mississippi

Experimental Investigation of Impurities and Their Effect on Acousto-Electric Properties of Lithium Niobate

The functional parameters of Lithium niobate that is used in various acousto-opto-electronic applications are questionable. The nonclassical nonlinear effect such as “acoustical memory” is not explained at full. Despite there being publications on crystal defects in Lithium niobate, the relationship between the defects and Acoustical Memory has not yet been established. Previous publications analyzed the Acoustical Memory effect without going into the microstructural detail of the level of point defects. The purpose of this research is to establish a connection between the microscopic point defects and the macroscopic nonlinear phenomena. The present research aims at finding new crystal characteristics including the identification of impurities and point defects, the distribution of the defects along the optical crystallographic z axis, and in a direction normal to the z axis. Bulk crystals and wafers are studied. The impurities are identified by their characteristic lines in the photoluminescence spectra, which are taken at room temperature in a range of 350 to 900 nm. The spectra reveal the following point defects: Ar, Ba, Cs, F-color center, Rb, Ru, Sn, Fe, K, Li, O, Nb, Kr, NbLi⁴⁺, Xe, etc. The peak corresponding to the F-center is found at 400.429 nm and has the highest number of photon counts. Further, the samples are shifted with a step of tens of microns along the z-axes or normal to it. This optical scanning allows to find a distribution of the impurities in the samples. The photon counts changes with crystal position for some impurities. The distribution of these defects is observed as peaks and valleys. The results may be used to discover the physical mechanisms behind nonclassical nonlinear phenomena in Lithium niobate.

Matteo Rini
Deputy Editor
American Physical Society

Science Communication: Take Charge of It!

Scientists have a responsibility to share the meaning and implications of their work, but receive little training in communication, and often feel unprepared to communicate with the public, the media, public officers and others outside their own field. In this talk, I will discuss how our journal Physics (htttp://physics.aps.org) strives to communicate research to a broad audience and share some thoughts and tips on science communication from my experience as a writer, editor, press officer and scientific consultant to policy makers.

Mairi Sakellariadou
Department of Physics
King's College — London

Unweaving the Fabric of the Universe

Our conventional understanding of space-time, as well as our notion of geometry, break down once we attempt to describe the very early stages of the evolution of our universe. The extreme physical conditions near the Big Bang necessitate an intimate interplay between physics and mathematics. The main challenge is the construction of a theory of quantum gravity, the long-sought unification of Einstein's general relativity with quantum mechanics. There are several attempts to formulate such a theory; they can be tested against experimental and observational results coming from high energy physics and astrophysics, leading to a remarkable interplay between gravity, particle physics and cosmology.

Karelle Siellez
Center for Relativistic Astrophysics
Georgia Institute of Technology

The Coincidence Between Gamma-Ray Bursts and Gravitational Waves: the Dawn of the Multi-Messenger Era!

Last year, while we celebrated the 100th anniversary of the Theory of the General Relativity of Einstein, we also detected the first direct observation of Gravitational Waves. LIGO opened the new area of Gravitational Wave Astrophysics with the detection of the coalescence of two black holes. Neutron star mergers (either double neutron star or neutron star - black hole systems) and collapsing massive stars are the next candidates for the detection of Gravitational Waves. They are though to be also the progenitor of respectively short and long Gamma-Ray Bursts. A detection in coincidence of both the Gravitational Waves and the electromagnetic emission would open the era of multimessenger astrophysics.

To detect those coincidences between GRB and GW, LIGO uses a different analysis that searches for a GW triggers coincident within some time window and sky position of a GRB in nearly real time thanks to the GCN sent by the satellite. We estimated the rate of coincident events that could be detected during the next run of O2 using observations in one hand and Monte Carlo simulations on the other. The small number of coincidence could be improved by using the untriggered GRBs missed by the Fermi GBM satellite. Thanks to a new code developed by the GBM team, we will discuss about the new kind of coincident detection that we could obtain.

This talk will describe the search of Gravitational Waves associated to GRBs. We will show the motivations and analysis made for the untriggered searches as well as the implication of those untriggered GRB on the expected rate of coincident event, the classification of long and short GRBs, and the possible new kind of progenitor for short GRBs at low redshift.

Hartmut Grote
Division of Laser Interferometry and Gravitational Wave Astronomy
Albert Einstein Institute — Hannover, Germany

The Physics of Climate, the IPCC, and the Public Discourse:
A Tour D'Horizon of Global Warming

Global warming is a topic of broad scientific inquiry as well as societal relevance. I will review the basic principles of climate physics, explain the role of the IPCC in assessing different aspects of global warming, and will try to shed some light on the public discourse around global warming and forces trying to obstruct the science.

Mauricio Richartz
Centro de Matemática
Universidade Federal do ABC — Brazil

Analogue Black Holes: Theory and Experiments

Analogue models of gravity, introduced by Unruh in 1981, have been (for some time now) very helpful towards a better theoretical understanding of several crucial phenomena at the boundary of gravity and quantum field theory. Experimental research on analogue models, however, started only very recently. In this talk, I will explain the basic theory behind analogue models of gravity and how they can be used to mimic important quantum field theory effects in curved spacetimes, like Hawking radiation. I will also focus on some experimental realizations of analogue models of gravity, including one based on surface waves propagating on water. which I have been involved with very recently (arXiv: 1612.06180).

Graduate Students
Department of Physics and Astronomy
University of Mississippi

Temperature Dependent Behavior of Shear Waves in a Micellar Fluid (Sunethra Dayavansha)
Development of Brain Tissue-Mimicking Phantom (Somayeh Taghizadehghahremanloo)
Negative Refraction and Super-resolution by a Steel-methanol Phononic Crystal (Ukesh Koju)
Development of a Tilt-free Seismometer (Reza Afrough)
The RKKY Interaction for Link Variables on the Square Lattice (Huu Do)
Experimental Test of an Omnidirectional Acoustic Enhancement Method (Maryam Landi)
Deforming the Fredkin Spin Chain Away from its Frustration-free point (Khagen Adhikari)

Maarten Buijsman
Division of Marine Science
University of Southern Mississippi

The Equatorial Pacific "Graveyard" for Semidiurnal Internal Tides: Incoherence or Dissipation?

The jets in the equatorial Pacific Ocean of a realistically-forced global circulation model with a horizontal resolution of 1/12.5 degree yield a strong loss of phase coherence in semidiurnal internal tides that propagate equatorward from the French Polynesian Islands and Hawaii. This loss of coherence is determined with a baroclinic energy analysis, in which the semidiurnal-band terms are separated into coherent, incoherent, and cross terms. For time scales longer than a year the coherent energy flux approaches zero values at the equator, while the total flux is 500 W/m. The time-variability of the incoherent energy flux is compared with phase speed variability computed with the Taylor-Goldstein equations. The variability of monthly-mean Taylor-Goldstein phase speeds agrees well with the phase speed variability inferred from steric sea surface height phases extracted with a plane-wave fit technique. On monthly time scales, the loss of phase coherence in the equatorward beams from the French Polynesian Islands is attributed to the time variability in the sheared background flow associated with the jets and tropical instability waves. On an annual time scale, the effect of stratification variability is of equal or greater importance than the background flow is to the loss of coherence. The model simulation suggests that low-frequency jets do not noticeably enhance the dissipation of the internal tide, but merely decohere and scatter it. Thus, the apparent demise of coherent internal tides seen in satellite altimetry maps of the equatorial Pacific may be due to incoherence rather than dissipation.

Carlos Herdeiro
Departamento de Física
Universidade de Aveiro — Portugal

Can a Black Hole Have Hair?

Black holes are one of the most fascinanting predictions of Einstein's theory of General Relativity. In their most paradigmatic guise, they are also the simplest objects in the Universe, made solely of space and time. Moreover, powerful mathematical theorems, known as uniqueness theorems, show that the way space and time can curve into a black hole is quite restricted, and these objects are only described by two parameters: their total mass and angular momentum. John Wheeler famously coined this simplicity into the mantra "Black Holes have no hair". But underlying this statement there is an unproved belief known as the "no-hair conjecture".

I will start by discussing observational evidence for the existence of black holes in the universe. Then, I will explain why the existence of some simple types of matter, even if Einstein's theory holds, could challenge the no-hair conjecture and produce "hairy" black holes. Finally, I will discuss how ongoing and forthcoming electromagnetic and gravitational waves observations could test the existence of black hole "hair" of this sort.

Seth Hopper
Gravitation in Técnico
Instituto Superior Técnico — Portugal

Bound and Unbound Motion Around Static Black Holes

A massive two-body system will interact gravitationally. Depending on the velocities and separation of bodies, their motion may be bound and periodic (as in the Earth-Sun system) or unbound (like a comet that passes the Sun only once). General relativity predicts that each of these systems will radiate energy in the form of gravitational waves. However, the qualitative difference between the systems implies that different techniques must be used to analyze them. In this talk I will briefly introduce the mathematical theory behind gravitational radiation of two body systems (specifically in the extreme mass-ratio regime) and consider how one can efficiently compute that radiation for different classes of problems.

Andrea Nerozzi
Gravitation in Técnico
Instituto Superior Técnico — Portugal

The Problem of Gauge Fixing in the Newman-Penrose Formalism

Since its introduction the Newman-Penrose formalism has been widely used in analytical and numerical studies of Einstein's equations, like for example for the Teukolsky master equation, or as a powerful tool for wave extraction in numerical relativity. The problem of gauge fixing, or more specifically, tetrad fixing is however still debated and only partially understood when the NP formalism is used to extract gravitational waves from numerical simulations.

In this talk I will approach the whole formalism with the goal of finding an invariant expression for all the variables in the NP formalism, namely Weyl scalars and the spin coefficients, once a specific yet generally defined tetrad is chosen.I will show that it is possible to do so, and give a general recipe for the task, as well as an indication of the quantities and identities that are required. The applications and importance of this approach to the problem of wave extraction in numerical relativity will be discussed.

Laura Bernard
Gravitation in Técnico
Instituto Superior Técnico — Portugal

Dynamics of Compact Binary Systems at the Fourth Post-Newtonian Order

Templates of coalescing compact binaries' gravitational waveform are used for the detection and precise determination of the physical parameters of gravitational waves by the current and next generations of interferometric detectors. In order to compute the waveform with high accuracy, the dynamics of compact binary systems should be known to the same precision. In this talk, I will address the question of the dynamics of non-spinning compact binary systems at the fourth post-Newtonian order in harmonic coordinates. I will present a method based on a Fokker action adapted to the specificities of the post-Newtonian formalism, including the so-called tail effects which appear for the first time in the conservative dynamics at 4PN. I will then derive the energy and periastron advance for circular orbits and show a full agreement with previous results from gravitational self-force calculations.

Sabrina Savage
Science Research Office
Marshall Space Flight Center

Reconnecting with Solar Flares

Because the Earth resides in the atmosphere of our nearest stellar neighbor, events occurring on the Sun's surface directly affect us by interfering with satellite operations and communications, astronaut safety, and in extreme circumstances, power grid stability. Solar flares, the most energetic events in our solar system, are a substantial source of hazardous space weather affecting our increasingly technology-dependent society. While flares have been observed using ground-based telescopes for over 150 years, modern space-bourne observatories have provided nearly continuous multi-wavelength flare coverage that cannot be obtained from the ground. We can now probe the origins and evolution of flares by tracking particle acceleration, changes in ionized plasma, and the reorganization of magnetic fields. I will walk through our current understanding of why flares occur, show several examples of these fantastic explosions, and describe the technology and instrumentation being developed at Marshall Space Flight Center to observe these phenomena.

Ulrich Sperhake
Theoretical Astrophysics
California Institute of Technology

Searching for Smoking Gun Effects of Modified Gravity in Supernova Core Collapse

Even though Einstein's theory of general relativity has been an incredibly successful theory and passed a plethora of tests ranging from light bending to the recent detection of gravitational waves, there are indications from theory, astrophysics and cosmology that modifications to the theory may ultimately be required. One of the most popular modifications applied to general relativity is the addition of a scalar field as an extra channel to mediate gravity. Through the introduction of additional degrees of freedom such scalar-tensor theories may explain some of the potentially troublesome phenomena in gravity while preserving compatibility with solar system and other tests. In this talk we explore the dynamics and gravitational wave emission of supernova core collapse in scalar tensor theory for the case of spherical symmetry. We analyse the resulting waveforms and explore under which conditions they may provide smoking gun signals detectable with present and future gravitational-wave detectors.

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 Astronomy
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
Department of Physics
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.

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.

Graduate Students
Department of Physics and Astronomy
University of Mississippi

Graduate Student Research Symposium

Matthias Kaminski
Department of Physics and Aastronomy
University of Alabama

Gauge/Gravitational Holography — Strong Physics far from Equilibrium

One natural question within physics is the choice of fundamental variables for describing nature. Is gravity more fundamental than quantum field theory? The holographic principle has lead us to a re-formulation of quantum field theories in terms of gravitational theories, or vice versa. After an introduction to the concepts of this emerging field, we are going to discuss applications to experimentally testable observables, and apply new ways of thinking about non-perturbation physics at strong coupling, and potentially the fabric of spacetime.

Jake Bennett
Department of Physics
Carnegie Mellon University

Amplitude Analysis: A Powerful Tool for Hadron Spectroscopy

Extracting useful information from experimental data is often far from straightforward. This is particularly true for studies in hadron spectroscopy that seek to determine the properties of constituent quark states. The presence of multiple, often broad, states leads to potentially intricate interference patterns that make the extraction of meaningful information challenging. Amplitude analysis is a powerful tool to disentangle the effects of interference and extract useful properties of hadronic states. This information is vital for a deeper understanding of the fundamental laws of nature. In this talk, I will review the experimental challenges that are associated with amplitude analysis, as well as its potential as a tool for hadron spectroscopy at Belle II.

Brian Anderson
Department of Physics and Astronomy
Brigham Young University

Listening For Cracks Using Resonance And Time Reversal Techniques To Prevent Radiation Leakage From Nuclear Storage Containers

Spent nuclear fuel is often stored in stainless steel canisters in the United States. Stainless steel is susceptible to Stress Corrosion Cracking (SCC). This presentation will discuss progress on the use of the Time Reversed Elastic Nonlinearity Diagnostic (TREND) and Nonlinear Resonant Ultrasound Spectroscopy (NRUS) to determine whether SCC is present and attempt to quantify the depth of the cracking. NRUS is the measurement of the amplitude dependence of a sample's resonance frequency, which occurs because of a softening of the elastic modulus in damaged media. NRUS provides a global indication of damage in a sample. TREND employs time reversal acoustics, which focuses wave energy at various points of interest to excite localized high amplitude. The amplitude dependence of this localized energy allows pointwise inspection of a sample.

Aaron Zimmerman
Canadian Institute for Theoretical Astrophysics
University of Toronto

Black Holes, Alone and in Pairs

The recent detections of gravitational waves have revealed an invisible side of the universe: black holes in binaries. These observations test our understanding of black holes, their violent mergers, and the theory of general relativity. A combination of analytic approximations and full numerical simulations is required to understand black hole binaries and predict the gravitational waves they emit. I will take us on a tour of these systems, discuss the “ringdown” of the final merged black hole, and present the most recent results from the Advanced LIGO and Virgo detectors.

Jessica McIver
Division of Physics, Mathematics and Astronomy
California Institute of Technology

Gravitational Wave Astrophysics: A New Era of Discovery

Large-scale interferometric detectors including LIGO and Virgo sense gravitational waves; minuscule fluctuations in space-time from the most extreme phenomena in the Universe. The recent detection of gravitational waves by LIGO and Virgo in concert with an associated electromagnetic counterpart was a breakthrough in multi-messenger astronomy that confirmed the association between neutron star collisions and short gamma-ray bursts (GRBs) and yielded new insight into the physical engine driving GRBs. Future gravitational wave observations have the potential to provide critical insight into key open questions in astrophysics, including the distribution of compact objects in the Universe, the evolution of compact binary systems, galaxy formation, and the explosion mechanism of core-collapse supernovae.

I will present the major outstanding challenges in gravitational wave astrophysics, including searching for transient signals in noisy data that contains a high rate of transient noise artifacts. I will discuss future prospects for how this quickly growing field will shape our understanding of the Universe.

Dan Cherdack
Department of Physics
Colorado State University

Searching for CP-Violation with the DUNE Experiment

Of the four known fundamental forces the weak force has many unique properties. It is the only standard model force that couples to all known fermions, that has massive exchange bosons, and that induces particle flavor changes. Even more surprising is that the weak force maximally violates parity symmetry, and has even been demonstrated to break charge-parity (CP) symmetry, meaning the weak force interacts differently with matter and anti-matter. This last property may hold the key to understanding several fundamental mysteries of the universe from the three-generation structure of matter, to the missing link between the big bang and the observed universe.

Neutrinos only interact via the weak force which means they are hard to detect, but provide a unique test bed for studying the weak interaction. Over the past few decades it was discovered that neutrinos have mass and change flavors. Studying the way neutrinos change flavors, termed neutrino oscillations, allows us to search for a new source of CP-violation. The next-generation Deep Underground Neutrino Experiment (DUNE) will usher in an era of high precision neutrino physics with the worlds most intense neutrino beam and high resolution Liquid Argon (LAr) Time Projection Chamber (TPCs) detectors. The Fermilab Short-Baseline Neutrino (SBN) Program will employ three LAr TPCs, which will provide and excellent test bed for LAr TPC R&D, and allow for many important measurements crucial to DUNE. I will discuss the theoretical framework we use to describe neutrino oscillations, and the exciting opportunities and new challenges afforded us by these experiments.

Tony Jun Huang
Pratt School of Engineering
Duke University

Acoustofluidics: Merging Acoustics and Microfluidics for Biomedical Applications

The past two decades have witnessed an explosion in lab-on-a-chip research with applications in biology, chemistry, and medicine. The continuous fusion of novel properties of physics into microfluidic environments has enabled the rapid development of this field. Recently, a new lab-on-a-chip frontier has emerged, joining acoustics with microfluidics, termed acoustofluidics. Here we summarize our recent progress in this exciting field and show the depth and breadth of acoustofluidic tools for biomedical applications through many unique examples, from exosome separation to cell-cell communications to 3D bioprinting, from circulating tumor cell isolation and detection to ultra-high-throughput blood cell separation for therapeutics, from high-precision micro-flow cytometry to portable yet powerful fluid manipulation systems. These acoustofluidic technologies are capable of delivering high-precision, high-throughput, and high-efficiency cell/particle/fluid manipulation in a simple, inexpensive, cell-phone-sized device. More importantly, the acoustic power intensity and frequency used in these acoustofluidic devices are in a similar range as those used in ultrasonic imaging, which has proven to be extremely safe for health monitoring during various stages of pregnancy. As a result, these methods are extremely biocompatible; i.e., cells and other biospecimen can maintain their natural states without any adverse effects from the acoustic manipulation process. With these unique advantages, acoustofluidic technologies meet a crucial need for highly accurate and amenable disease diagnosis (e.g., early cancer detection and prenatal health) as well as effective therapy (e.g., transfusion and immunotherapy).

Harry Swinney
Center for Nonlinear Dynamics
University of Texas — Austin

Universality in Nature

In the seventeenth century Newton thought about the gravitational force between the earth and an apple falling from a tree, and he said “I began to think of gravity extending to the orb of the Moon.” This led him to postulate that his gravitational force law is a universal law of nature, applying to any two masses in the universe. We now know that there are three other fundamental universal forces in nature, the electromagnetic and the strong and weak nuclear forces. Systems of many atoms or molecules can similarly exhibit universal behavior. For example, studies of phase transitions in the 20th century culminated with Kenneth Wilson's theory of universality in phase transitions of systems as different as fluids and magnets. The present talk examines spatial patterns that emerge in systems driven away from thermodynamic equilibrium by imposed gradients in pressure, temperature, or nutrient concentration. Experiments and mathematical models provide insights into the formation of patterns in physical, chemical, and biological systems, as will be illustrated through examples that reveal mathematical similarity in phenomena such as in the fractal wrinkling of flower petals and plastic sheets.

Tyrone Porter
Department of Mechanical Engineering and Biomedical Engineering
Boston University

Tensionless Bubbles and Exploding Droplets

Fluid-filled particles play a pivotal role in biomedical applications of ultrasound. This talk will cover two examples, lipid-coated microbubbles and vaporizable nanoemulsions, highlighting their interesting nonlinear dynamics and utility. Due to their compressibility, microbubbles are more echogenic than tissue, making them ideal ultrasound contrast agents. The microbubble surface must be coated with surface-active molecules such as lipids in order to reduce the interfacial tension and stabilize the microbubble against dissolution. The interfacial tension is a function of lipid surface density, which varies from zero upon deep compression to that of an uncoated bubble upon expansion. The forces acting on the microbubble wall vary as the interfacial tension changes, resulting in a nonlinear response to acoustic excitation. Using monodisperse lipid-coated microbubbles, we have studied this nonlinear behavior, including pressure-dependent resonance frequency and subharmonic emissions at ultralow excitation pressures. In contrast to microbubbles, liquid perfluorocarbon nanoemulsions are incompressible and thus poorly echogenic. The nanoemulsions can be vaporized with high pressure acoustic pulses. The phase conversion is immediate and highly energetic and thus resembles an explosion on a microscale. The resultant bubbles can be used to transiently permeabilize cell membranes, thus enabling drug delivery to intracellular targets, or can be used to enhance tissue absorption of ultrasound, making ultrasound-mediated ablation more efficient. These studies provide insight into the unique nonlinear behavior of these fluid-filled particles and how they may be leveraged for exciting biomedical applications.

David Meyer
Department of Mathematics
University of California — San Diego

Data Science and Quantum Gravity

Data, even “big data”, is finite, and thus discrete. A common goal is to describe them as the outcome of a random process specified by a small number of parameters; doing so at least compresses the data, and at best explicates the process by which they were generated. Some important approaches include low-rank matrix factorization and multi-dimensional scaling, both of which reveal a geometry behind the data. Such interplay between the discrete and the continuous is familiar in theoretical and computational physics, from the definition and regularization of path integrals to numerical methods for fluid dynamics. In this talk I'll explain how recent data science results in non-metric multidimensional scaling provide a new perspective on the Hawking-Malament theorem that is the foundation of the causal set program for quantum gravity. I'll describe a new algorithm for embedding causal sets in Lorentzian manifolds motivated by this perspective. And I'll end with some speculations about possible quantum dynamics for causal sets. Familiarity with the causal set program for quantum gravity will not be assumed.

Mir Emad Aghili, Vishal Baibhav, and Shrobana Ghosh
Department of Physics and Astronomy
University of Mississippi

Presentations by Graduate Students

"Manifoldlikeness of Causal Sets" by Mir Emad Aghili
Abstract: We study the distribution of maximal-chain lengths between two elements of a causal set, and its relationship with the embeddability of the causal set in a region of flat spacetime. We start with causal sets obtained from uniformly distributed points in Minkowski space. After some general considerations we focus on the 2-dimensional case and derive expressions for the expected number nk of maximal chains as a function of their length k, the most probable maximal-chain length k₀, and the width Δ of the length distribution, as functions of the number N of causal set elements in the interval between the two points. These results, together with the results of numerical simulations of causal sets embedded in Minkowski space of various dimensionalities, show that for a given N the values of k₀ and Δ can be used to estimate the dimensionality of a causal set embeddable in Minkowski space. Other dimension estimators are known for manifoldlike causal sets, but the length distribution also gives us a way to evaluate the embeddability of a causal set. We provide a first test of manifoldlikeness based on k₀ and Δ, and end with a few simple examples of nk distributions for non-manifoldlike causal sets.

"Systematic Errors and Energy Estimates in Binary Black Hole Ringdown" by Vishal Baibhav
Abstract: High signal-to-noise ratio gravitational wave observations will enable us to measure the quasinormal frequencies of binary black hole merger remnants. In general relativity, these frequencies depend only on the remnant's mass and spin, so they can be used to test general relativity and the Kerr nature of the remnant. To carry out these tests, systematic errors must be subdominant with respect to statistical errors. I'll talk about how accurately ringdown frequencies can be extracted from state-of-the-art numerical simulations from the Simulating eXtreme Spacetimes (SXS) catalog. I'll also present some results on the relative excitation of different quasinormal modes. To quantify these excitations, one must define a suitable “starting time“, e.g. by maximizing the energy content “parallel” to a quasinormal mode (as suggested by Nollert). We used Nollert's method to quantify the energy radiated in quasinormal modes for aligned-spin binaries, and we produced post-Newtonian inspired fits of the resulting energy estimates.

"Detectability of Gravitational Radiation from Superradiant Instabilities" by Shrobana Ghosh
Abstract: An incident wave, when scattered off a black hole may get amplified, at the expense of the rotational energy of the black hole. This process is known as superradiance and due to this rotating black holes can serve as particle detectors. For a massive field, the mass of the field helps in confining the field. Therefore, even an ultralight bosonic field can form a non-axisymmetric cloud around the black hole due to repeated amplification from the black hole. This leads to emission of gravitational radiation that can be detected by ground-based or space-based gravitational wave detectors, depending on the mass of the boson. Based on astrophysical models we show that adLIGO should see 10⁴ events in a 4 year mission for a scalar field mass of 3×10^-12 eV, while LISA will see about 10³ events in a 4 year mission for a scalar field mass of 10^-17 eV. In the absence of detection at a particular detector, we can rule out the corresponding mass range of the scalar field. We also look at the detectability of such events from the remnants of the merger events already seen by adLIGO at the present and future ground-based detectors.

Bruno Uchoa
Department of Physics and Astronomy
University of Oklahoma

Topology and Quantum Phenomena in Nodal Matter

Nodal matter describes a new metallic form where the Fermi surface collapses into sets of points or lines, and is not stabilized by Fermi pressure but by symmetries. The non-trivial quantum phenomena of those systems are described by topology, a field of mathematics that studies properties that remain invariant under continuous deformations of shapes and surfaces. In the first part of the talk I will give a general overview of the field. In the second one, I will describe a particular class of nodal materials where the Fermi surface has the shape of closed lines. I will show that interactions can drive this system into an exotic topological phase in three dimensions (3D) known as the 3D anomalous quantum Hall effect, where the system has spontaneous and topologically protected surface currents.

Mukunda Acharya, Khagendra Adhikari, and Xudong Fan
Department of Physics and Astronomy
University of Mississippi

Presentations by Graduate Students

"Sound Speed Profiles of the Global Ocean calculated from Physical Oceanographic Data" by Mukunda Acharya
Abstract: Sound speed profiles in the global ocean are useful for modeling of sound propagation over the global oceans. This talk presents the sound speed profiles calculated from physical oceanographic data that were collected in the world ocean circulation experiment. They are data of conductivity, temperature, and pressure, taken from multiple cruises with a typical spacing of 60 km along the route of each cruise and consisting of an elaborate series of zonal (east-west) and meridional (north-south) coast-to-coast cruises across the global oceans. Nearly 8000 sound speed profiles were mapped out that were then used to determine the dependence of sound speed minimum and depth for those minima on the longitude and latitude. Based on the characterization, practical formulas of the dependence were given.

"Deforming the Fredkin Spin Chain Away from its Frustration-free Point" by Khagendra Adhikari
Abstract: The Fredkin model describes a spin-half chain segment subject to three-body, correlated-exchange interactions and twisted boundary conditions. The model is frustration-free, and its ground state wave function is known exactly. Its low-energy physics is that of a strong xy ferromagnet with gapless excitations and an unusually large dynamical exponent. We study a generalized spin chain model that includes the Fredkin model as a special tuning point and otherwise interpolates between the conventional ferromagnetic and antiferromagnetic quantum Heisenberg models. We solve for the low-lying states, using exact diagonalization and density-matrix renormalization group calculations, in order to track the properties of the system as it is tuned away from the Fredkin point. We identify a zero-temperature phase diagram with multiple transitions and unexpected ordered phases. The Fredkin ground state turns out to be particularly brittle, unstable to even infinitesimal antiferromagnetic frustration. We remark on the existence of an “anti-Fredkin” point at which all the contributing spin configurations have a spin structure exactly opposite to those in the Fredkin ground state.

"Enhancing Sound Emission by Using Subwavelength Metacavities" by Xudong Fan
Abstract: Efficient directional emission of sound waves is critical in imaging and communication, yet is held back by the inefficient emission of a small source. A change in the surrounding environment of an acoustic source can lead to enhanced emission and mode conversion. This talk will present frames of enclosing small sound sources in subwavelength meta-cavities to achieve sound enhancement and conversion with high efficiency. The enhancement is an analog of modifying spontaneous emission rate of a quantum source in a resonant cavity. The enhancement by a subwavelength meta-cavity offers a practical path toward miniaturization in applications that demand efficient emission, such as sonar, loudspeakers, or ultrasound transducers.

S.T.E.M. Fest 2018 at the University of Mississippi

The physics department will participate in the 2018 S.T.E.M. Fest.

Friday, April 20, 2018

• Physics Open House. Learn why a curve ball curves or how to hit the perfect home run from the Society of Physics Students.
  Lewis Hall & Swayze Field 3 - 5 PM.
• National Center for Physical Acoustics Tours. Discover cutting-edge research on a variety of acoustic phenomena, from ultrasonic to infrasonic. NCPA, 3 PM & 4 PM.
• Hidden Figures: The movie. The 2016 blockbuster presented by the Women in Physics and the Office of Diversity and Community Engagement. Overby, 5 - 7:15 PM.
• Astronomy Open House: Viewings of the moon and Jupiter with the historic 1893 Grubb telescope, weather permitting.
  Kennon Observatory, 8 - 10 PM.

Saturday, April 21, 2018

• Lightning Research at UM Field Station. Lecture on lightning and atmospheric physics by Professor Tom Marshall.
  Field Station, 10:40-11am.
• Fun Demos at UM Field Station. Explore the physics of sound, a fire tornado, liquid nitrogen, and what happens when you lay down on a bed of nails. Field Station, 2:30-3:30pm.

Deidre Shoemaker
School of Physics
Georgia Institute of Technology

Numerical Relativity in the Age of Gravitational Wave Observations

The advent of gravitational wave astronomy has created opportunities to probe strong-field gravity as we measure the merger of black holes. Numerical relativity provides the means to confront the measurements with theoretical prediction. In this talk, I'll discuss the role numerical relativity played in the observed black hole binaries by LIGO and Virgo and the future potential for unveiling strong-field gravity in both future ground and space based detectors.

Emanuele Berti
Department of Physics and Astronomy
University of Mississippi

Strong Gravity and Astrophysics with Compact Binaries at the Dawn of Gravitational-wave Astronomy

Einstein's general relativity has passed all experimental verifications with flying colors, but cosmological observations and difficulties in quantizing gravity suggest that general relativity should be modified at some level. Strong-field modifications of general relativity (if they occur in nature) will in general affect the dynamics of black holes and neutron stars, with potentially observable signatures. Therefore compact objects - whether in isolation or in binary systems - are excellent astrophysical laboratories for high-energy physics and strong-field gravity. Furthermore, the gravitational radiation emitted during the inspiral and merger of compact binaries encodes important information on their astrophysical formation mechanism. I will discuss potential smoking guns of modified gravity in gravitational-wave detectors, and the theoretical and observational challenges associated with their search. I will also discuss the potential of Earth- and space-based detectors to further our understanding of the formation and evolution of compact binaries.

Zheguang Zou
National Center for Physical Acoustics
University of Mississippi

Underwater Sound Propagation in Estuarine Environments

Estuaries are shallow-water regions that are highly dynamic due to a variety of environmental variability, such as tidal flow, water mixing,
wind-driven water surface waves, etc. The environmental variability has significant effect on underwater sound propagation and acoustic
communication. This talk will present some of these effects in the Delaware bay. The examinations include water-column variations due to tidal
dynamics, and surface variations due to wind-wave dynamics. The results gain insight into the link between physical environments and underwater
acoustic fields, suggesting the demanding of next-generation underwater acoustic communication systems for dynamic oceans.

Robert J. Doerksen
Department of BioMolecular Sciences
University of Mississippi

Laws of Physics Applied to Molecules: Accurate Electronic Structure Calculations and Molecular Dynamics Simulations

Quantum mechanics, classical mechanics (so-called “molecular mechanics”) and molecular dynamics (which could be classical- or quantum-based) methods can be used to study molecules and molecular systems to provide accurate fundamental properties, to compare to experimental results or to provide insight. In this seminar I will give a brief explanation of a variety of fundamental calculation approaches. I will illustrate the use of the methods for solving practical problems with calculations of optical rotations, NMR chemical shifts and electronic circular dichroism spectra that assist in assigning the absolute configuration of newly discovered natural product molecules and molecular dynamics simulations used to study the role of allosteric modulators of cannabinoid receptors.

Parsa Bakhtiari Rad
National Center for Physical Acoustics
University of Mississippi

3D Seismic Oceanography: The New Frontier in Ocean Water-Column Exploration

Seismic oceanography is a newly-introduced technique that links exploration seismology and physical oceanography. It consists of the application of the multi-channel seismic reflection method, commonly used in the oil and gas industry to image the subsurface geological structure, to the investigation of the fine structure of the ocean interior. Seismic reflection sections provide high quality images of the oceans fine structures with higher vertical and horizontal resolution and complement conventional physical oceanography measurements and logs. These images consist of seismic reflections that occur and are recorded whenever a seismic wave traveling in a heterogeneous media encounters interfaces between different water layers and is reflected back to the surface and recorded by special receivers. This talk will report the implement of a three dimensional (3-D) seismic study to better image the ocean interior. A very large seismic data set collected from the Mississippi canyon in the Gulf of Mexico is used to produce the 3-D seismic images of the ocean interior. The initial images obtained using massive hardware/software efforts exhibit promising results for further studies.

Eyal Schwartz
Department of Physics and Astronomy
University of Mississippi

Single Atoms Dynamics in Tight Optical Tweezers

One of the enduring ambitions in atomic physics is to build an understanding of interacting macroscopic systems completely from knowledge of the underlying microscopic dynamics. In recent years, experimental advancements in the near-deterministic isolation and control of single atoms, paved the way for this connection of the few-body and many-body regimes. As experimental techniques in engineering atom-atom interactions become more reliable and widespread, further opportunities for direct observations of quantum phenomena come to light.

In this talk I will give an overview of our past and present work. From laser cooling and trapping of a single atom in optical tweezers, through different manipulations to study few body dynamics in an atomic level. I will detail our latest works of “Thermally-robust spin correlations between two atoms” and “Direct measurements of collisional dynamics in ultra-cold atom triads”.

Our facility gives a push button mechanism for future quantum chemistry, quantum computers and cool fundamental quantum experiments to explore the relations between the micro and macro worlds.

Stefanos Kourtis
Physics Department
Boston University

Quantum-inspired Approaches to Hard Computational Problems

Many classes of complex computational problems admit no efficient solution or even approximation, yet have a vast reach in applications across science and industry. From a physics perspective, computational complexity originates from strong correlations between bits of information. It is reasonable to ask whether computational approaches to quantum many-body problems can be practically useful in this context. In this talk, I will present newly found cases where the answer is affirmative. I will introduce constraint satisfaction problems (CSPs) and reformulate them as interacting models whose ground states represent the solution manifold. A procedure that reaches the ground states of these models implements a protocol of computation. In some protocols, the complexity that arises during computation can be viewed as quantum entanglement, and efficiency is achieved by controlling its growth. Using this reasoning, I will introduce practical methods for solving CSPs based on tensor network contraction and demonstrate that they outperform state-of-the-art solvers for some of these problems by a significant margin. I will conclude with an outline of ongoing work on extensions and applications to problems of current interest, such as the simulation of existing and near-term quantum circuits.

Surajit Sen
Department of Physics
State University of New York at Buffalo

A New Look at Nonlinear Dynamics - Fundamental Physics, Shocks and Metamaterials

Nonlinear dynamics as a subject began in the late 1600s and matured into a broad based area in the late 20^th century. The talk will shed light on the breadth of the subject, the characters that seem to inhabit the nonlinear world, how they interact, and the newly introduced quasi-equilibrium phase. What nonlinear dynamics gives us in terms of making novel metamaterials and technologies will be highlighted.

Ryan C. Fortenberry
Department of Chemistry
University of Mississippi

Quantum Chemistry and Spectroscopy: A Match Made in the Heavens

The chemistry of the Earth is tied to only a small set of conditions while most of the rest of the Universe is often grossly different from terrestrial circumstances. Consequently, astrochemical experiments can be quite difficult to perform, but quantum chemistry does not suffer the same difficulties. Here, quantum chemistry is applied to the prediction of gas-phase spectroscopy and molecular formation of various “unstable” molecular systems including radicals, cations, and anions. The spectra of seemingly strange species including proton-bound complexes (i.e. OC—H⁺—CO), noble gas molecules (i.e. ArCH₂⁺, NeON⁺, & ArOH⁺), premineral molecules (i.e. Mg₂O₂ & MgF₂), and odd bonding in chalcogen hydrides (H₂S—S⁺) have been produced and even linked with laboratory and astrophysical detections. The applications of these findings stretch from the esoteric of cool and novel chemistry to indicators of early stages of planet formation even to abiotic molecular oxygen synthesis in comets, atmospheres, and the early Earth.

Karim Sabra
George W. Woodruff School of Mechanical Engineering
Georgia Institute of Technology

Ocean Remote Sensing Using Passive Acoustics

Acoustic waves carry information about their environment as they propagate, especially in the ocean which can conduct sound very efficiently over significant distances. Hence underwater acoustic waves can be exploited for a wide variety of ocean remote sensing activities. Modern acoustic remote sensing involves receiver arrays and array signal processing to recover multidimensional results, for instance the characterization of medium inhomogeneities due to sound speed fluctuations or discrete sound scatters. On one hand receiver arrays are becoming increasingly autonomous, miniaturized and capable of long term deployment thus enabling the practical use of acoustics for ocean remote sensing applications. However, on the other hand, conventional acoustic remote sensing techniques still typically rely on controlled active sources which can be problematic to deploy and operate over the long term, especially if multiple sources are required to fully illuminate the ocean region of interest. To address this crucial limitation, totally passive versions-i.e. using only receiver arrays- of existing remote sensing techniques can be developed by taking advantage of uncooperative sources of opportunity (e.g. shipping noise) or the ubiquitous ocean ambient noise which have not typically been used in traditional ocean sensing applications due to their apparent complex nature. This fully passive approach can also be advantageous when regulations forbid the use of active sound sources to prevent the disruption of natural animal activities or when no active sources are readily available-e.g. at very low frequencies (~10Hz) or during covert operations. This presentation will discuss recent development of ocean remote sensing using passive acoustics notably 1) Passive acoustic thermometry to estimate deep ocean temperatures variations using coherent processing of low-frequency ambient noise, 2) Localization of drifting sensor networks using ambient noise to enable random volumetric ad-hoc receiver array for tracking underwater targets; and 3) Monitoring of shallow water sound channel using shipping sources of opportunity. Additionally the extension of these passive remote sensing techniques to seismic and structural health monitoring applications will also be presented.

Baharak Sajjadi
Department of Chemical Engineering
University of Mississippi

Efficient Carbon Modification for Sustainable Food/Energy/Water Nexus

Climate change mitigation is arguably the leading grand challenge facing mankind. Our critical reviews of physical modifications (Reviews in Chemical Engineering, 2018. in press, doi.org/10.1515/revce-2017-0113) and chemical modifications (Reviews in Chemical
Engineering, 2018. in press, doi.org/10.1515/revce-2018-0003) of biochar in addition to our experimental results suggest that acoustic, photochemical and plasma treatments, in selected reaction environments and conditions; are capable of inducing either structural or functional group changes on carbonaceous materials. These tunable, low energy treatments have potential to mitigate climate change through a number of transformative tracks.

The pioneering work of our transdisciplinary team revealed that single-staged ultrasound and photochemical treatments of
biochar in H₂O with dissolved CO₂ results in fixation of C from CO₂ on biochar, fixation of H from water on biochar, mineral leaching by water including minerals detrimental to gasification, increase in biochar's heating value (due to the 3 processes stated above), and increase in biochar's internal surface area (AIChE Journal, 2014. 60 (3):1054-1065). These synergisms seem to be tunable by feedstock, reactants stoichiometry and reaction conditions in pyrolysis, and treatments (Fuel, 2019. 235:1131-1145). Carbon and hydrogen fixations seem to be connected to the formation of H₂, CO, formic acid, formaldehyde, and associated radicals during sonolysis of aqueous CO₂. Similar to ultrasound waves, non-thermal plasma  can split water vapor and CO₂ to excited chemicals and fuels including methanol, H₂ and CO (Current Opinion in Green & Sustainable Chemistry, 2017. 3:45-49). The presence of carbon in the plasma system has not been explored. However, treatment of biochar in non-thermal chlorine plasma yields a high adsorption capacity of elemental mercury in flue gas due to the creation of Cl-active sites (Chemical Engineering Journal, 2018. 331C:536-544).

In this seminar, we will discuss the potential routes of the observed synergisms in mitigation of climate change through CO₂
capture/recycle, energy production through advanced gasification, Remediation of global carbon cycle (Fuel, 2018. 225
:287-298) & water resource (Ultrasonics Sonochemistry, 2018, in press). These treatments can also open new routes for tackling challenges such as water desalination through functionalized defected graphene membrane.

Andrea Welsh
School of Physics
Georgia Institute of Technology

Coming Together: Individuals at Different Scales Working for A Common Goal

Patterns in time and space are ubiquitous in everyday life, from the formation of structure by cell morphogenesis, to the coloration of animal's skin and fur, to the construction of large sand dunes from the driving and dissipation of the environment. My thesis can be classified into two threads: investigating the formations of patterns by the collective motion of systems — such as swarms of brine shrimp and human spiral waves — and the exploration of “chimera states,” a spatio-temporal pattern with more than one distinct behavior, both of which occur in biologically-relevant models of excitable tissue. I use a combination of computer simulation, mathematical methods, and table-top experiments to study these instances of pattern formation and learn how they are formed in biological systems, as well as the relevant physical parameters that control what sort of patterns are formed. Investigation of these systems have important consequences in how we understand our world, quantify and predict their dynamics and gain insights on why some patterns are physically chosen over others, and how to control them for our benefit.

Thomas Werfel
Department of Chemical Engineering
University of Mississippi

Targeted Therapies at the Interface of Nanotechnology and Cancer Biology

In the Interdisciplinary NanoBioSciences (iNBS) Lab, we work largely at the interface of nanotechnology and cancer biology. The complexity of cancer necessitates creative, multi-faceted solutions that nanotechnologies have the potential to offer. However, the successful application of nanotechnologies is currently stymied by oversimplified biological models and a dearth of data from advanced biological studies that faithfully recapitulate human disease. Ultimately, our scientific goals are to better understand nanomaterial-biological system interactions to improve the performance of nanotechnologies in humans, discover new cancer molecular targets ideal for nanotechnology-based therapies, and identify cellular and molecular processes that impact drug delivery efficiency, cancer metastasis, and resistance to therapy. In this colloquium, I will highlight three research thrusts in the iNBS Lab that span nanotechnology and targeted cancer therapy: 1) Drugging previously 'undruggable' cancer-causing genes with siRNA nanomedicines, 2) Combating the immunosuppressive impact of efferocytosis in the tumor microenvironment, and 3) Targeting the platelet-tumor cell interaction to prevent breast cancer metastasis.

Kyle Parfrey
Astrophysics Division
NASA Goddard Space Flight Center

The Magnetic Lives of Black Holes and Neutron Stars

The most extreme and surprising behaviors of black holes and neutron stars are driven by their surrounding plasmas and magnetic fields. Numerical simulations which capture basic physical processes like particle acceleration, magnetic reconnection, and magneto-rotational turbulence can yield insight into such disparate phenomena as black-hole jets and X-ray coronae, magnetar giant gamma-ray flares, and the spin limit of millisecond pulsars. I will focus on what simulations can teach us about the launching of relativistic jets in compact binary mergers, and will describe how a new technique for general-relativistic plasma kinetics will aid in understanding black holes' jets and particle acceleration, and in interpreting future observations with the Earth-spanning Event Horizon Telescope.

Shaon Ghosh
Department of Physics
University of Wisconsin — Milwaukee

Astrophysics with Synergy of Electromagnetic and Gravitational Wave Observations

About three and a half years ago, the direct detection and measurement of gravitational waves from a pair of coalescing black holes by the LIGO interferometers opened a new window for astrophysicists to look into the universe. Almost two years later, the discovery of gravitational wave from a binary neutron star system marked the beginning of the era of joint electromagnetic and gravitational wave astronomy. In this talk, I will present a brief history of this discovery and its importance in that context. I will then focus on the rich scientific results of the multi-messenger observation and finally, discuss how such joint observations can help us extract astrophysical information from some of the most extreme objects in the universe. Specifically, I will highlight how observations of neutron stars can help us understand how matter behaves in conditions that cannot be replicated in earth-based laboratories. The required information for such studies comes to us from various avenues of astrophysical observations. I will delineate the methods that we will be employing in combining these information to make robust inferences on the neutron star equation of state.

Stephen Taylor
Division of Physics, Mathematics and Astronomy
California Institute of Technology

Frontiers of Multi-Messenger Black-Hole Physics

The bounty of gravitational-wave observations from LIGO and Virgo has opened up a new window onto the warped Universe, as well as a pathway to addressing many of the contemporary challenges of fundamental physics. I will discuss how catalogs of stellar-mass compact object mergers can probe the unknown physical processes of binary stellar evolution, and how these systems can be harnessed as standard distance markers (calibrated entirely by fundamental physics) to map the expansion history of the cosmos. The next gravitational-wave frontier will be opened within 3-6 years by pulsar-timing arrays, which have unique access to black-holes at the billion to ten-billion solar mass scale. The accretionary dynamics of supermassive black-hole binaries should yield several tell-tale signatures observable in upcoming synoptic time-domain surveys, as well as gravitational-wave signatures measurable by pulsar timing. Additionally, pulsar-timing arrays are currently placing compelling constraints on modified gravity theories, cosmic strings, and ultralight scalar-field dark matter. I will review my work on these challenges, as well as in the exciting broader arena of gravitational-wave astrophysics, and describe my vision for the next decade of discovery.

David Nichols
Institute of Physics
University of Amsterdam

Gravitational Waves and Fundamental Properties of Matter and Spacetime

Gravitational waves from the mergers of ten binary black holes and one binary neutron star were detected in the first two observing runs by the Advanced LIGO and Virgo detectors. In this talk, I will discuss the eleven gravitational-wave detections and the electromagnetic observations that accompanied the neutron-star merger. These detections confirmed many of the predictions of general relativity, and they initiated the observational study of strongly curved, dynamical spacetimes and their highly luminous gravitational waves. One aspect of these high gravitational-wave luminosities that LIGO and Virgo will be able to measure is the gravitational-wave memory effect: a lasting change in the gravitational-wave strain produced by energy radiated in gravitational waves. I will describe how this effect is related to symmetries and conserved quantities of spacetime, how the memory effect can be measured with LIGO and Virgo, and how new types of memory effects have been recently predicted. I will conclude by discussing the plans for the next generation of gravitational-wave detectors after LIGO and Virgo and the scientific capabilities of these new detectors. These facilities could detect millions of black-hole and neutron-star mergers per year, and they can provide insights on a range of topics from the population of short gamma-ray bursts to the presence of dark matter around black holes.

Sarah Vigeland
Department of Physics
University of Wisconsin — Milwaukee

Probing Massive and Supermassive Black Holes with Gravitational Waves

Observations have shown that nearly all galaxies harbor massive or supermassive black holes at their centers. Gravitational wave (GW) observations of these black holes will shed light on their growth and evolution, and the merger histories of galaxies. Massive and supermassive black holes are also ideal laboratories for studying strong-field gravity. Pulsar timing arrays (PTAs) are sensitive to GWs with frequencies ~1-100 nHz, and can detect GWs emitted by supermassive black hole binaries, which form when two galaxies merge. The Laser Interferometer Space Antenna (LISA) is a planned space-based GW detector that will be sensitive to GWs ~1-100 mHz, and it will see a variety of sources, including merging massive black hole binaries and extreme mass-ratio inspires (EMRIs), which consist of a small compact object falling into a massive black hole. I will discuss source modeling and detection techniques for LISA and PTAs, as well as present limits on nanohertz GWs from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) collaboration.

Anuradha Gupta
Department of Physics
Pennsylvania State University

Physics and Astrophysics with Gravitational Waves from Compact Binary Coalescences

The recent detections of gravitational waves from several binary black holes and binary neutron star mergers have opened up new avenues for gravitational wave astronomy and astrophysics. These detections provide us with great opportunities to study astrophysical sources in both weak and strong gravity regimes. In this presentation, I'll tell you how one does physics and astrophysics with gravitational waves emitted from compact binary coalescences. In particular, how to constrain binary formation mechanisms from their observed properties, how to test general relativity and other theories of gravity and lastly how to do precision cosmology with gravitational waves. I'll also touch upon the future prospects of these efforts.

Libo Jiang
Department of Physics & Astronomy
University of Pittsburgh

MicroBooNE - Using Neutrinos to Probe Nuclear Physics for the Future

MicroBooNE is a large 170-ton liquid-argon-Time Projection Chamber Neutrino experiment located on the Booster neutrino beamline at Fermilab. The detector serves as a next step in a phased program towards the construction of massive kiloton scale LArTPC detectors for future long-baseline neutrino physics (DUNE) and is the first detector in the short-baseline neutrino program at Fermilab. A major physics goals of the experiment is to probe the source of the anomalous excess of electron-like events in MiniBooNE/LSND with improved detection capabilities. In addition, MicroBooNE has an extensive cross section physics program that will improve current models on neutrino-nucleus interactions, especially nuclear effects in argon, and decrease systematic errors in the oscillation program. This colloquium introduces the detector & performance of MicroBooNE and summarizes the status of MicroBooNE's neutrino cross section analyses.

Jonathan Eisch
Department of Physics & Astronomy
Iowa State University

Reviving the Poltergeist: Bringing Water-Based Neutrino Experiments into the Precision Era with Efficient Neutron Detection

Advances in water-based neutrino-detection technology are setting the stage for a new generation of detectors to answer questions about the nature of matter in the universe and to make our world a safer place. Leading the way in these new technologies is the Accelerator Neutrino Neutron Interaction Experiment (ANNIE) at Fermilab. ANNIE will revisit the use of neutron capturing salts, pioneered in the first experiment to detect the neutrino, to detect the number of neutrons produced in GeV-scale neutrino interactions. This measurement, the first on a neutrino beam, will help push future neutrino-oscillation experiments into the precision era by separating quasi-elastic charged-current interactions from more complicated many-body neutrino interactions and thus improving the models of neutron production in neutrino interactions. The WATCHMAN experiment, under construction in the UK, will use the same technology at a much larger scale to demonstrate the ability to remotely monitor nuclear reactors from tens of kilometers away. This demonstration will enable remote reactor monitoring to be a part of future nuclear nonproliferation treaties. In this talk, I will describe the ANNIE and WATCHMAN experiments along with their impacts on detector technology development toward future large multipurpose neutrino detectors like Theia.

Gavin Davies
Department of Physics
Indiana University

The Wonderful World of Neutrino Oscillations

In 1998 it was discovered that neutrinos oscillate and have mass which led to the award of the 2015 Nobel Prize in Physics. That discovery generated a global campaign to better understand neutrino properties using oscillations of neutrinos produced in the Sun, in the atmosphere, at reactors, and by accelerators. The community has learned much but several important questions remain such as: Which neutrino is heaviest? Do neutrinos break the symmetry between matter and antimatter? Are there more than three neutrino types?

In my talk, I will introduce neutrinos and the questions surrounding them, their chameleon-like flavor-changing behavior, and the experiments that hunt for them including the leading-edge, international Deep Underground Neutrino Experiment.

Jingbo Wang
Department of Physics
University of California — Davis

Exploring the Neutrino Physics with the Deep Underground Neutrino Experiment

One of the biggest surprises in particle physics is that the neutrinos have mass, which was discovered by the neutrino oscillation experiments. This fundamental property of neutrinos leads to some new questions. What is the ordering of the neutrino mass states? Do the neutrinos violate the matter/antimatter symmetry? What characteristics does the neutrino mixing matrix have? The Deep Underground Neutrino Experiment (DUNE) will address these questions with the high-precision Liquid Argon Time Projection Chamber (LArTPC) technology. In this talk, I will give a brief overview of neutrino oscillations, then describe DUNE and its physics programs. I will also talk about the Pulsed Neutron Source as a newly proposed calibration technique for liquid argon TPCs. The precision measurements of the neutrinos will open a window to new physics beyond the standard model. The future and prospects will be discussed.

Xiaobo Chao
National Center for Computational Hydroscience and Engineering
University of Mississippi

Three Dimensional Numerical Modeling of Temperature Distribution in a High Dam Reservoir with the Effect of Channel Curvature on Mekong River

A three dimensional numerical model has been developed to simulate the flow circulation as well as temperature distribution in a high dam reservoir with the effect of channel curvature. In the model, the density induced buoyant force on the turbulent flow is considered. This “buoyancy-extended version of k-ε model” is used for turbulence closure, and the flow velocity and temperature distribution are simulated simultaneously. The model was first validated using a laboratory case of turbulent buoyant flow in a curved open channel. The secondary flow circulation in the curved channel was simulated and the temperature distribution in the channel was validated using experimental data. The model was then applied to simulate the flow and temperature distribution in Xiaowan Reservoir, a high dam reservoir on Mekong River, with deep water depth and curvature affect. The numerical results are generally in good agreement with field observations. The thermal stratification, temperature distribution in the reservoir and the effect of channel curvature on the temperature distribution are discussed.

Jason Fry
Department of Physics
University of Virginia

Precision Fundamental Symmetry Measurements With Cold Neutrons

The neutron can be used as a powerful tool to study a wide range of phenomena through many disciplines of physics. In particular, cold neutrons are utilized in condensed matter, nuclear, and particle physics with deep connections to cosmology. The free neutron has a slightly larger mass than the proton leading to far reaching implications. How long a free neutron lives determines how the light elements formed in the early universe. The kinematics of neutron decay give us insight into how quarks mix in the weak interaction. Additionally, as a neutral particle, neutrons can penetrate deeply into nucleons to further our understanding of how the strong and weak interaction mix at the smallest scales. In this talk, I will discuss the neutron physics experiments carried out and planned on the Fundamental Neutron Physics Beamline (FNPB) at the Spallation Neutron Source at Oak Ridge National Lab. The NPDGamma experiment, the first experiment on the FNPB, studied the most fundamental process in the Hadronic Weak Interaction (HWI) and the results set the best constraint for future investigation of the HWI. Currently we are commissioning the Nab experiment on FNPB which will make precise measurements of the electron neutrino correlation parameter "a" and the Fierz interference term "b" in unpolarized neutron beta decay. These results will lead to a new, precise, independent determination of the ratio λ = GA/GV that will sensitively test CKM unitarity.

Glenn M. Walker
Department of Electrical Engineering
University of Mississippi

Microfluidics: Thinking Small to Improve Biological Research

Microfluidics is the study of fluid behavior at micrometer length scales and the development of devices that leverage microscale fluid phenomena. A major focus of the field has been on solving problems in biology since biological cells typically range in size from 1–20 micrometers and are difficult to manipulate with traditional instruments. Researchers have been able to exploit the manipulation of fluid volumes down to the picoliter to enable biological experiments that were previously impossible. This talk will cover some of the microscale phenomena that become dominant at micrometer lengths and also show examples of enabling biological experiments. Research from our lab on high throughput screening and cancer cell hypoxia will also be presented.

Saeed Kamali
Department of Physics and Astronoimy
University of Mississippi

New Physics in Inclusive B → X_c τ ν_τ Decays in Light of R(D^*) Measurements

Kevin Lin
Department of Physics and Astronomy
University of Mississippi

Development of Vibrational Metrics for Internal Damage Scenarios of a Scaled Transnuclear-32 Dry Storage Cask for Spent Nuclear Fuel

The assessment of the internal structural integrity of dry storage casks for used high burnup nuclear fuel assemblies is of critical importance before transporting these to permanent repositories. The large size and structural complexity of the Transnuclear-32 (TN-32) cask as well as the inability to access its interior make this a challenging task. To address these difficulties, we use an active acoustics approach to develop metrics that are sensitive to the internal configuration of these casks. A 6:1 scaled model of the TN-32 cask was constructed in order to study internal configuration of the fuel assemblies including various damage scenarios. The vibration modes were verified in Finite Element simulations. Each mock-up fuel assembly consists of bundled steel rods, and their structural failure is mimicked by steel shot of equal weight. This talk will report the amplitude- and phase-based active acoustics metrics we developed to characterize different levels of internal damage. Our studies indicate that vibrometric signatures of various internal conditions can be measured using sources and sensors mounted on the exterior shell. Our current methodology is sensitive enough to detect structural failures at the single fuel assembly level.

Robert Lirette
Department of Physics and Astronomy
University of Mississippi

Droplet Extraction and Manipulation at a Fluid Interface Using Fraxicon Modified Ultrasound

Ultrasound focused at a fluid-fluid boundary creates an acoustic radiation pressure on the boundary that is dependent on the incident energy density and the relative density and sound speed of each fluid. For different fluid combinations this radiation pressure can either be positive or negative. For this study ultrasound propagating from water to carbon tetrachloride was used to create a negative radiation pressure at the interface. This fluid combination is impedance matched eliminating reflections and heating effects at the boundary. A fraxicon phase plate lens is a low profile analog of an axicon and generates an approximate Bessel beam in the far field. The near field exhibits a complex diffraction pattern including shadow zones capable of acoustic trapping. Starting with a planar interface, we demonstrate the extraction, capture, and manipulation of a carbon tetrachloride droplet. The negative radiation pressure draws the carbon tetrachloride surface up into the water, eventually breaking a droplet free. The trapped droplet is then transported through the water by moving the transducer.

Roger Waxler
Department of Physics and Astronomy
University of Mississippi

Infrasound Generation and Propagation in the Earth's Atmosphere

The term infrasound is applied to low frequency sound in the atmosphere, generally below the limit of human hearing. The frequencies of interest in our research range from 10 Hz down to as low as 0.001 Hz, corresponding to periods of 0.1 to 1000 seconds. Such signals tend to be geophysical in nature, propagating globally and generated by large, violent events such as hurricanes, tornadoes, earthquakes and large detonations. Their propagation depends critically on large scale temperature and wind velocity gradients. These produce a variety of acoustic ducts in the atmosphere. These are asymmetric with respect to azimuth and interact with each other. They are also spatially and temporally varying, with small scale fluctuations on top of diurnal and seasonal cycles. An overview of sources, generation and propagation of infrasound in the atmosphere will be presented.

Bhubanjyoti Bhattacharya
Department of Natural Sciences
Lawrence Technological University

CP Violation in the Precision Era

Anomalies in recent data present strong hints of physics beyond the Standard Model. Several new physics models, among them vector bosons and leptoquarks, have proven to be viable candidates in light of the data. Intensity frontier experiments will soon test many of these models through precision measurements of low-energy observables. In this talk I will present a subset of recent measurements that come with a hint of new physics. I will present proposals for testing and distinguishing between some of the popular new physics models, by using CP violating observables.

Department Students
Department of Physics and Astronomy
University of Mississippi

Reports on Summer Research

Carl Jensen
Transducer Technology Group
Bose Corporation

Sound Reproduction and Loudspeaker Structural Modes

Many familiar sources of sound involve vibrating structures like a piano sound board, an acoustic guitar's body, drums, and all kinds of vibrating machinery. Similarly, almost all technologies for mechanically producing sound also work by exciting some kind of vibrating structure as well, but, in sound reproduction, the goal is to recreate the original recording as accurately as possible. So the fact that all vibrating structures exhibit modal behavior can be good or bad: the diversity and excitation of modes in musical instruments lends them their unique sonic qualities and richness, but these same characteristics are very much unwanted in a loudspeaker meant for accurate reproduction. In this presentation, I'll discuss some of the principles of sound reproduction and perception as well as laying out how we can use computer simulations to untangle the complex acoustic behavior of these modes to understand their behavior and make better sounding loudspeakers.

Michel Villanueva
Department of Physics and Astronomy
University of Mississippi

Searches of New Physics with the Belle II Experiment

Despite the large success shown by the Standard Model of Elementary Particles describing subatomic processes, there are still many open questions in nature that cannot be explained by the Standard Model. Solving the issues faced by the Standard Model requires the introduction of new particles or interactions, which, if they exist, can be observed as deviations from the predictions of suppressed or forbidden processes. The Belle II experiment will play a critical role in searches for new physics at the "intensity frontier". First collisions took place in 2018 at the new SuperKEKB accelerator, which is expected to operate for the next decade, collecting 50 times more data than the previous generation of experiments of this kind. In this talk, the data production and physics programs of the Belle II experiment are presented, in which the High Energy Physics group of the University of Mississippi contributes to key roles. Of particular interest in my research are decays of the tau lepton, which provide a clean environment to the study of QCD related processes.

Tomas Galvez
Department of Physics and Astronomy
University of Mississippi

Quantum Cosmology and Sound Waves in the Early Universe

In this talk, we will review some of the conundrums of standard big bang cosmology and a few proposals designed to circumvent them. To do so, we study the quantum origin of perturbations in a perfect (or imperfect) fluid and show some useful techniques to calculate their corresponding two-point correlators. Our objective is to improve the accuracy and efficiency of the existing methods to evaluate primordial power spectra of scalar and tensor fluctuations, and therefore provide solid observational constraints. Our approach is to rewrite all the relevant equations of motion in terms of slowly varying quantities, which is important to consider the contribution from high-frequency modes to the spectrum without affecting computational performance. We do not require additional approximations to reproduce all the features in the power spectrum for each specific early universe model.

Department Students
Department of Physics and Astronomy
University of Mississippi

Reports on Summer Research

David Craig
Department of Chemistry and Physics
West Texas A&M University

From Astronomy to Acoustics and Back Again Through Undergraduate Research

After earning my PhD in physical acoustics at Ole Miss and a number of years at institutions almost exclusively devoted to teaching, I returned to active research by joining a team of astrophysicists working on projects that emphasize undergraduate research in observational cosmology. I will discuss the ways undergraduates have been involved in cutting-edge research via this team approach and overview the science behind the projects.

Our emphasis has been on HI (21 cm) radio surveys of nearby galaxies. These include the completed ALFALFA blind survey of the nearby universe, and the current targeted Arecibo Pisces-Perseus Supercluster Survey (APPSS) which attempts to detect dark matter-driven infall of galaxies onto a nearby supercluster filament. I will include a discussion of the observing strategies and the planned use of the baryonic Tully-Fisher relation to separate the effects of cosmic expansion and local peculiar velocities using Bayesian statistical methods.

Department Students
Department of Physics and Astronomy
University of Mississippi

Reports on Summer Research

Logan S. Marcus
Office of the Deputy Assistant Secretary of Defense for Chemical and Biological Defense
ANSER, Inc.

Careers in Science Outside of Academia

There is generational change in the way that scientists must approach their careers after graduating. According to Science Magazine, “…for U.S. science and engineering Ph.D.s, private sector employment (42%) is now nearly on par with educational institutions (43%).” Graduating students must be prepared to enter a job market that includes opportunities beyond traditional academic careers. In this presentation, I will discuss some of the many options for careers in science that are outside of the traditional academic path. I will explore example careers, offer advice to students on how to prepare themselves for those careers, and discuss skills that the University can emphasize to equip graduates before they leave Ole Miss.

Annemarie Exarhos
Department of Physics
Lafayette College

A Path Toward Spin-Based Quantum Technologies — Creating, Controlling, and Characterizing Quantum Emission

Optically-active point defects in wide-bandgap semiconductors are the basis for rapidly expanding quantum technologies in nanoscale sensing and quantum information processing. Most research has focused on three-dimensional host materials such as diamond and silicon carbide, where quantum mechanical spin states can be optically addressed. In recent years, the two-dimensional van der Waals material hexagonal boron nitride (hBN) has emerged as a robust host for bright, stable, room-temperature quantum emitters (QEs). However, many questions persist regarding the chemical and electronic structure of the defects responsible for emission as well as the potential role of spin-related effects. Significantly complicating the identification of these QEs is the heterogeneity of optical and magnetic characteristics observed.

I will discuss work regarding our studies of the optical and magnetic properties of QEs in hBN films, characterized via confocal fluorescence microscopy. In particular, I will report on our recent observations of magnetic-field dependent emission in some QEs that, if able to be well-isolated and controlled, could enable the realization of spin-based quantum technologies using low-dimensional van der Waals heterostructures.

Dr. Stuart Loch
College of Sciences and Mathematics
Auburn University

Spectroscopy of Laboratory and Astrophysical Plasmas: Applications for Fusion Plasmas, Merging Neutron Stars, and Planetary Nebulae

Plasmas are hot, ionized gases and are often called the fourth state of matter. Plasmas make up most of the observable Universe and laboratory plasmas have a wide range of research applications. Diagnosing the properties of plasmas presents a particular challenge, due to their temperatures and in the case of astrophysical plasmas, the large distances to the objects. Plasma spectroscopy represents a non-invasive method of diagnosing important plasma properties such as temperatures, densities, and elemental compositions. An overview is given of three research projects, involving the use of quantum mechanics calculations for diagnosis of laboratory plasmas. The projects involve measuring wall erosion rates from fusion plasma experiments, investigating the spectral emission from elements made in neutron star mergers, and the confirmation of a new atomic process found in planetary nebulae.

Jake Bennett, Roger Waxler, and Gavin Davies
Department of Physics and Astronomy
University of Mississippi

Departmental Research

There will be a brief report on some of the fields of research by our department. It will consist of the following:
Jake Bennet: Belle II
Roger Waxler: Infrasound
Gavin Davies: NOνa/Dune

James Bonifacio
Department of Physics
Case Western Reserve University

Giving the Graviton a Mass

In general relativity, the gravitational force is mediated by a massless spin-2 particle…the graviton. In fact, the structure of general relativity and its interactions with other particles are largely fixed by this requirement. However, there are still many open questions about the behavior of gravity, both at short and long distances, which motivates the exploration of theories that deform general relativity. One such question is whether the graviton in our universe can have a small but nonzero mass. In this talk I will review some of the challenges and successes in constructing theories of massive gravitons and discuss some recent experimental and theoretical results that constrain such theories.

Shanti Bhushan
Mechanical Engineering
Mississippi State University

Computational Fluid Dynamics: Turbulence Modeling and Applications

Turbulence/transition modeling is a primary source of uncertainty in computational fluid dynamics, and this problem remains unsolved despite over one hundred years of scientific research. The talk will focus on an overview of author's ongoing research in transition/turbulence modeling and applications. The key modeling topics that will be discussed are: identification of transition onset marker for bypass transition; modeling subgrid scale energy transfer using algebraic models; and potential of machine learning for turbulence modeling. The key application topic will focus on role of turbulence on: growth of vortical structures for ship flows; heat transfer; structural deformation for shock boundary layer interaction; growth of rotor wake; and propagation of acoustic waves. Some open question in transition/turbulence will also be emphasized.

Dustin Madison
Department of Physics and Astronomy
West Virginia University

Advancing the Capabilities of Nanohertz Gravitational Wave Astronomy

After fifteen years of ongoing effort to precisely monitor the most stable millisecond pulsars known, the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) is poised, within the next five years, to detect gravitational waves (GWs) in an entirely unexplored range of frequencies. The initial detection will be just the beginning of a sustained campaign to characterize the nanohertz GW sky. I will discuss important fundamental features of the astrophysics underpinning and motivating NANOGrav's efforts and certain unavoidable shortcomings of pulsar timing array investigations. I have a plan to ameliorate these shortcomings by synthesizing pulsar timing data and precise astrometric surveys from instruments such as the Gaia space telescope, a program that could powerfully augment both the imminent and long-term scientific returns of nanohertz GW astronomy. Finally, I will discuss a new and interesting way that astrometric measurements could enable the detection of GW memory, a theoretically important signal sought after by GW astronomers across the frequency spectrum.

Gregory Vieira
Department of Physics
Rhodes College

Patterned Nanoscale Magnetic Traps and Applications for Single- and Few-Molecule Experiments

Directed and controllable manipulation of fluid-borne entities is important for a wide range of applications such as cellular diagnostics and nano-scale assembly. We present a multiplexed mechanism for manipulating microscopic magnetic particles in fluid on arrays of patterned magnetic disks or wires. This mechanism allows for probing and manipulation of micro- and nano-scale objects and biological entities in near-native environments, offers the flexibility to apply forces to large numbers of objects simultaneously, and is remotely tunable by application of weak magnetic fields. We illustrate several applications of this technique in the regime of single or few molecules: toward single biomolecule detection, single cell nanoinjections, and remote control of microtubules gliding on kinesin assays.

Yuan Li
Department of Astronomy
University of California — Berkeley

Supermassive Black Hole Feedback in the Centers of Massive Galaxies and Galaxy Clusters

The centers of massive galaxies and galaxy clusters contain hot plasma that loses its energy rapidly through radiation of X-ray photons. The energy loss is thought to be compensated for by the energy input from the supermassive black holes (SMBHs) in the centers of these systems, via a process often termed as "AGN feedback". In this talk, I will review the state of the field, and discuss what we have learned from numerical simulations in the past few years, including how AGN jets deposit their energy to the surrounding medium, and how they affect cooling and star formation. I will also talk about my recent analysis of optical and ALMA observations of multiphase filaments in cluster centers, which not only improves our understanding of AGN feedback, but also puts unprecedented constraints on microscopic transport processes in the weakly-collisional, magnetized intracluster plasma.

Philip Cowperthwaite
Carnegie Observatory
Carnegie Institution for Science

Electromagnetic Follow-Up of Gravitational Wave Events in the Next Decade

The Advanced LIGO and Virgo (ALV) gravitational wave interferometers began their third observing run (O3) in April of 2019. Since then they have so far reported the detection of over 30 gravitational wave candidates. While the majority of detected events are likely to be the merger of two stellar mass black holes, several events have a better than 50% chance of containing at least one neutron star making them enticing targets for electromagnetic follow-up. In this talk, I will review the state of follow-up efforts and discuss the observational campaigns for two of these events: S190425z and S190814bv. To date, no credible electromagnetic counterparts have been identified for any of these events. Nevertheless, studying these follow-up efforts can provide valuable insight into the difficulties of obtaining joint detections of gravitational waves and electromagnetic signals. I will discuss how we can tackle these challenges with the next-generation of observational facilities set to come online in the 2020s.

Daniel D'Orazio
Institute for Theory and Computation
Harvard University

Multi-Messenger and Multi-Band Interrogation of Compact-Object Binaries

Binary systems consisting of two compact objects span at least ten orders of magnitude in mass, from the neutron stars and stellar-mass black holes paired via binary stellar evolution or dynamical encounters, to the supermassive black holes that meet at the centers of galactic nuclei. Accordingly, these systems arise from an enormously diverse range of astrophysical environments. What they share is their potential role in generating luminous, high-energy electromagnetic radiation and their ability to generate detectable gravitational radiation upon merger. I will discuss work aimed at electromagnetically identifying a yet undetected population of sub-parsec separation supermassive black hole binaries, which are targets of ongoing monitoring by the pulsar timing arrays as well as the future LISA gravitational-wave observatory. I will also discuss work that leverages detection of gravitational waves in multiple frequency bands to elucidate the astrophysical origin of the LIGO gravitational-wave events. In the coming years, present and upcoming time domain surveys (e.g., the Vera C. Rubin Observatory) and gravitational-wave observatories (e.g., LISA, LIGO and its evolutions) will drive forward investigations of compact-object binaries across the mass scale, and drastically expand our knowledge of compact-object binary populations and the environments that shape them.

Hsin-Yu Chen
Black Hole Initiative
Harvard University

Gravitational-wave Observations from Quarks to the Universe

Advanced LIGO-Virgo have detected tens of stellar mass compact binary mergers, including binary black holes, binary neutron stars, and potentially neutron star-black hole mergers. These binary-merger detections carried plenty of information about the binaries and the Universe. In this talk I will focus on a few topics we learned from the gravitational-wave detections: the electromagnetic counterparts of binary mergers, the neutron star equation-of-state, and the expansion rate of the Universe. I will first summarize current status of the field and the future projections. I will then discuss future plans to expand and improve the study.

Zheguang Zou
National Center for Physical Acoustics and Department of Physics and Astronomy
University of Mississippi

Three-Dimensional Seismic Oceanography in the Gulf of Mexico

Seismic oceanography is a new interdisciplinary science that uses legacy marine seismic data from the oil industry to image the ocean water column like eddies or oceanic internal waves. The imaging is achieved by acoustic signals emitted by air guns, reflected from the ocean, and collected by a hydrophone array towed by a ship. For a ship traveling in the ocean, the temperature-salinity structure of the water column can be imaged from the collected signals with a resolution much higher than traditional oceanography measurements.
Previous seismic oceanography studies are largely based on two-dimensional seismic images. However, the ocean by nature requires three-dimensional (3D) imaging with high resolution. This talk will report our recent results on the imaging of the temporal and spatial variation of water column fluctuations in the Gulf of Mexico enabled by 3D seismic oceanography.

Jake Bennett
Department of Physics and Astronomy
University of Mississippi

High Energy Physics at Ole Miss

The Department of Physics and Astronomy at Ole Miss contributes to major theoretical and experimental efforts in high energy particle physics, including several international experiments. This colloquium will include an introduction to the field and a review of some of the HEP research ongoing at Ole Miss.

Alejandro Cárdenas-Avendaño
Department of Physics
University of Illinois — Urbana-Champaign

Experimental Gravity with Electromagnetic and Gravitational Waves

Observations of black holes through the electromagnetic and gravitational spectrum have been used to understand their nature and the fundamental properties of the material in their vicinity. Our ability to learn about the underlying physics depends heavily on our understanding of the gravity theory that describes the geometry around these compact objects, and for the electromagnetic observations, also on the complex astrophysics that produces the observed radiation. In this talk, I will comment on our current ability to constrain and detect deviations from general relativity using (i) the electromagnetic radiation emitted by an accretion disk around a black hole, and (ii) the gravitational waves produced when comparable-mass black holes collide, and when a small compact object falls into a supermassive one in an extreme mass-ratio inspiral. I will also discuss the implications of assuming that General Relativity is correct a priori on the estimation of parameters of the astrophysical model when the data is not described by the Einstein’s theory, which can lead to a fundamental systematic bias.

Yun Jing
Graduate Program in Acoustics
Pennsylvania State University

Numerical Modeling of Medical Ultrasound

In the last two decades, we have witnessed enormous development in high intensity focused ultrasound (HIFU) for treating a broad spectrum of diseases and medical conditions. As a non-invasive surgical modality that can reach deep tissue, HIFU has the potential to revolutionize therapy. To truly understand, design and improve HIFU-based technologies and eventually adopt them clinically, it is vital to have a versatile and fast, yet accurate ultrasound numerical model. Although there are many ultrasound numerical models available, none can currently achieve both efficient and sufficiently accurate simulations for acoustic wave propagation in large-scale, heterogeneous biological media. Existing numerical models face two enduring dilemmas: they are either very efficient but not accurate due to invalid approximations, or they are very accurate but computationally time-consuming and therefore impractical in many cases. In this talk, I will discuss our effort throughout the past 10 years in developing new numerical models for HIFU, that aims to establish a balance between accuracy and computational efficiency, therefore filling the gap between these two critical requirements. I will focus on both the theoretical development and the practical applications of the numerical algorithm. I will also introduce our ongoing NIH-funded project that aims to develop an open-source toolbox for modeling medical ultrasound.

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Chen Shen
Electrical and Computer Engineering
Duke University;

Architected Materials: Next Generation Functional Acoustic Materials

The recent development of functional materials has reshaped almost every aspect of our lives. In modern society, we are able to synthesize structures with properties beyond their constituent materials — referred to as architected materials. My research focuses on the study of architected materials, including their design, fabrication, and application in acoustics. In this talk, I will sample some of my contributions to this field. For instance, (1) I will show how reconfigurable architected materials lead to multifunctional acoustic devices. (2) I will demonstrate the design of highly efficient architected materials for acoustic wave control. (3) I will discuss the potential of architected materials through marriage with advanced manufacturing. At the end of the talk, I will showcase some of my ongoing work on architected materials for medical and ultrasound applications.

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Philip L. Marston
Department of Physics and Astronomy
Washington State University

Decades of Acoustical, Optical, & Fluid Wave Physics with Students & Associates

Following introductory comments concerning a Washington State College Physics MS degree recipient from 1928, selected research from four recent decades will be summarized. Some examples to be considered include the close relationship between optical and acoustical scattering research and the value of understanding short and long wavelength scattering processes. Novel forms of rainbow and glory scattering were discovered. In some cases waves can be simultaneously used to probe and control the shape and position of drops and bubbles and to stabilize liquid columns; investigations outside the laboratory included reduced-gravity aircraft and the Space Shuttle. Related developments concern radiation torque, vortex beams, and tractor beams. In other developments, lessons from short-wavelength scattering experiments were applied to acoustical situations having reduced symmetry, facilitating improved interpretation of acoustical images and signatures of objects in water. Participation of students and program alumni in acoustical field experiments for the remediation of unexploded ordnance (UXO) will be noted.

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Meeting ID: 213 798 950

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Maarten Buijsman
School of Ocean Science and Engineering
University of Southern Mississippi

Giant Underwater Waves Mixing the Ocean's Waters

The ocean’s interior is filled with giant waves that can only exist because the ocean is vertically stratified in temperature and salinity. Some of these waves are more than 300 feet tall and 100 miles long. Like waves at the ocean surface, internal waves are restored by gravity. These internal gravity waves are generated by wind, tides, and the slow ocean circulation. As internal waves propagate through the ocean, they interact with topography, the ocean circulation, and other internal waves, facilitating an energy cascade to smaller scales, and eventually turbulence. Like breaking waves on the beach, the turbulence of breaking internal waves mixes the water below the ocean’s surface. This is relevant for the dispersion of sediments and nutrients, the general ocean circulation, and ultimately the earth’s climate.

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Meeting ID: 213 798 950

Seth Pree
Department of Physics and Astronomy
University of California — Los Angeles

Acoustic Plasma Trapping and Plasma Thermoacoustics

An oven's worth of microwaves can be used to both make a few thousand Kelvin plasma and cause that plasma to generate sound. Such a system can be used as a tweeter, but the luminous plasma subjected to its own sound field raises more interesting opportunities in both nonlinear acoustics and thermoacoustics. For example, how can the sound field established by modulating the microwave power lighting up a ping-pong ball sized bulb containing 30 mg of sulfur trap the resulting 3000+ K plasma in the center of a spherical cavity? Continuous wave (CW) microwaves may also be used to generate sound via the Sondhauss effect in a Helmholtz resonator. I will end by presenting an unconventional, 3D thermoacoustic gain mechanism based on the variation in the plasma’s conductivity due to the sound’s adiabatic compression. If realized, 3D plasma thermoacoustics may help addressing questions about Cepheid variable stars.

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Stewart Prager
Program of Science & Global Security
Princeton University

The Increasing Peril from Nuclear Arms: And How Physicists Can Help Reduce the Threat

With geopolitical and technological changes mostly driven by the nuclear weapons states, we are slipping towards a new arms race and deterioration of the multi-decade arms control regime. This talk will describe the current situation, feasible steps to reduce the nuclear threat, and a new project sponsored by the American Physical Society to engage physical scientists in advocacy for nuclear threat reduction.

A short meeting will be held immediately after the colloquium for those interested in learning about, or joining, the APS Coalition.

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Meeting ID: 213 798 950

Nobuchika Okada
Department of Physics and Astronomy
University of Alabama

Solving Big Mysteries in Particle Physics with a New Force

For the last decades, the Standard Model of particle physics has been the best theory for describing elementary particle phenomena observed in nature. However, there still are big mysteries that the Standard Model fails to explain: (1) Why are neutrino masses so tiny? (2) What is the nature of the dark matter in our universe? (3) What drives the Cosmological Inflation before Big Bang? (4) Where does ordinary matter come from, and what happened to antimatter? (5) Why is the CP-violation so small in the strong interaction? In this colloquium, I will first review the Standard Model, its success and fails, and then discuss our recent proposal of a simple extension of the Standard Model with a new force that offers a solution to the above 5 mysteries.

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Meeting ID: 213 798 950

Guancong Ma
Department of Physics
Hong Kong Baptist University

Geometric Phases in Acoustics

Geometric phase is a universal concept associated with the adiabatic evolution of states. It manifests in a wide diversity of physical systems, ranging from solid-state electronics to classical mechanics. Its profound implication makes it the cornerstone of numerous cutting-edge research, in particular, topological phases. The universality of the geometric phase means that it can be investigated using acoustic wave systems. The advancement of phononic crystals and the advent of acoustic metamaterials, in particular, laid the foundation for such endeavors. In this talk, I will discuss some of our recent attempts to study geometric phases and related phenomena in acoustic systems. Topics include: geometric phase mediated transport of sound vortex in a spiral waveguide, the realization of quantized Zak phase in a one-dimensional phononic crystal, topological acoustic pumping, and hybrid winding around an exceptional point.

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Meeting ID: 213 798 950

Charles F. Caskey
Department of Radiology & Radiological Sciences
Vanderbilt University Medical Center

Transcranial MR-guided Focused Ultrasound Neuromodulation

Ultrasound has the ability to focus energy to a small point beyond the skull and is being widely explored by researchers as a tool for non-invasive neuromodulation. When combined with magnetic resonance imaging (MRI), focused ultrasound (FUS) can be precisely guided while the effects of FUS can be visualized at the network level using fMRI. In this talk, I will discuss our ongoing work in developing systems to apply image-guided FUS neuromodulation in the MRI environment while imaging functional activity. Specifically, I will cover the development of optical tracking as a method to guide FUS neuromodulation, the creation of transducer arrays for steerable FUS neuromodulation, and the development of MR acoustic radiation
force imaging methods to visualize the acoustic focus. We have used these methods to modulate the somatosensory network in non-human primates, demonstrating that MRI-guided FUS is capable of exciting precise targets in somatosensory areas 3a/3b, causing downstream activations in off-target brain regions within the circuit which we can simultaneously detect with fMRI. Our observations are consistent with others' work in the field of FUS neuromodulation; however, questions remain about mechanisms underlying FUS neuromodulation and potential confounds. The talk will conclude by reporting on recent work at the cellular level where we are measuring calcium signaling in mouse brain slices with optical markers during FUS neuromodulation

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Meeting ID: 213 798 950

Kimberly Boddy
Department of Physics
University of Texas at Austin

Searching for Dark Matter Interactions in Cosmology

There is overwhelming evidence for the existence of dark matter. It plays a crucial role in the formation of structure in the Universe, yet little is known about its properties beyond gravitational effects. In this talk, I will discuss the current and future prospects of understanding the fundamental nature of dark matter using observations in cosmology and astrophysics. These observations offer glimpses into different cosmic eras that may shed light on the mystery of dark matter.

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Meeting ID: 213 798 950

Nathan E. Murray
National Center for Physical Acoustics
University of Mississippi

Two Examples of Turbulence Interactions

A brief introduction to turbulence, it’s characteristics and mechanisms, is presented. A conceptual model for turbulence is discussed. This is followed by two specific examples. First, the action of turbulence on the dispersion of solid particulate in a high-shear scenario in a gas-solid flow is explored. Second, the characteristics of turbulence in a transient, shock-driven acceleration are explored. In both examples, the “fingerprints” of turbulence are highlighted as they appear in statistical analyses of the data.

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Meeting ID: 213 798 950

Benjamin "B.B." Pilgrim
Department of Physics and Astronomy
University of Mississippi

The Chain Action and a Variational Principle for Two Dimensional Causal Sets

I will present the chain action for causal sets and evaluate its accuracy for causal sets embeddable in two dimensional manifolds. I will also propose a discrete variational principle, and the results of manifold-like causal sets will be compared to Kleitman-Rothschild causal sets.

Anil Panta
Department of Physics and Astronomy
University of Mississippi

Developing Tools for Analysis on the Open Science Grid

The Belle II dataset searcher is a tool to get the location of files that are stored on the open science grid for analysis use. I will report on my efforts to expand the usefulness of this tool by implementing a NoSQL database, called Elasticsearch, rather than the usual SQL database. With this change, it will be possible to make full text searches on dataset metadata, enabling a more efficient way for analysts to find the samples of interest.

Mukunda Acharya
Stewart Acoustical Consultants
Raleigh, North Carolina

From a MS Degree to Industry Career in Acoustics

The talk will be an overview of how I develop my career from a master degree in physics focusing on physical acoustics to my current job as an acoustical consultant in industry. Most of the talk would be focused on giving you a general idea of my career as an acoustical consultant. Acoustical consultants use a combination of scientific theory, analytical modeling tools, experimental data, experience, and judgment to analyze problems and provide advices for clients on acoustics related problems. Answers to some of the common problems can be immediate, but many problems require analysis, measurements, or both. I am going to share my experience about the knowledge and skills that are vital to becoming a professional acoustical consultant. I believe the talk will be helpful to graduate students who are planning to pursue their research in physical acoustics and continue in the future as a professional.

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Meeting ID: 213 798 950

Louis E. Strigari
Department of Physics and Astronomy;
Texas A&M University

Terrestrial and Astrophysical Applications of Coherent Neutrino Scattering

Coherent elastic neutrino-nucleus scattering (CEνNS) is a long-standing theoretical prediction of the Standard Model (SM), and the COHERENT experiment has recently achieved the first detection of it. CEνNS provides an important probe of physics beyond the SM. In addition, it can open up a new window into neutrino astrophysics, through studies of low energy neutrinos from the Sun, atmosphere, and supernovae. CEνNS is also vital for understanding and interpreting future particle dark matter searches. In this talk, I will discuss the prospects for learning about the nature of neutrinos and astrophysical sources from CEνNS detection, highlighting how astrophysical and terrestrial-based detections play important and complementary roles.

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Meeting ID: 213 798 950

Feng Guo
Intelligent Systems Engineering
Indiana University — Bloomington

Development of Acoustofluidics for Cancer Research

The acoustofluidics technology harnesses sound waves and microfluidics for the manipulation of cells and liquids. This technique has many unique advantages. Firstly, this technique handles cells and/or liquids using gentle mechanical vibrations. These vibrations create a pressure gradient in the medium to move suspended micro-objects yielding a contamination-free, contactless, and label-free manipulation. Secondly, acoustofluidics has minimal impact on cell integrity and function. Thirdly, this technology can operate in a single, inexpensive micro-device without complicated setups, which offer additional advantages in ease of use, versatility, and portability. Here, we report a series of acoustofluidic devices and systems for the manipulation of cells and liquids in the microfluidic environment to address the problems in the field of cancer biology and translational cancer medicine.

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Meeting ID: 213 798 950

David G. Grier
Department of Physics and the Center for Soft Matter Research
New York University

Holography and the Pandemic: Using Holographic Video Microscopy to Detect Viruses and Antibodies

The hologram of a microscopic object encodes information about that object's size, shape, composition and three-dimensional position. Often, that information is retrieved by computing a three-dimensional reconstruction of the complex medium and then analyzing the result. The three-dimensional reconstruction, however, contains no more information than the original two-dimensional hologram (and usually less). In special cases, the recorded hologram instead can be fit, pixel-by-pixel, to the exact Lorenz-Mie theory of light scattering. For a micrometer-scale colloidal sphere, this analysis yields the position to within a few nanometers over a range extending to hundreds of micrometers. More importantly, it yields the sphere's diameter to within a couple of nanometers. This is fine enough to monitor molecules and viruses binding to the surfaces of functionalized beads simply by watching the beads grow larger in real time. The same analysis yields the bead's refractive index with part-per-thousand resolution, which elegantly solves the barcoding problem for multiplexed binding assays. This talk will explain how to use holographic microscopy for precision particle characterization. It then will showcase a few practical and scientific applications that illustrate the power of the technique before diving into the emergency application for COVID-19

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Meeting ID: 213 798 950

Darin Van Pelt
School of Engineering
University of Mississippi

Rocket Physics and Experience with SpaceX

A discussion of my nearly 20yrs in the aerospace industry is presented. Those included nearly a decade at SpaceX and time as co-founder of ABL Space Systems, a launch vehicle company currently developing a vehicle capable of 1000kg to orbit. One interesting experience is leading the propulsion team in creating the Falcon 9 booster you see launching and routinely landing while delivering payloads to orbit and starlink satellites for the future of the internet. Efficiently and accurately landing a 150ft tall pencil is a special challenge and some of the physics involved will be discussed.

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Meeting ID: 213 798 950

Joshua B. Bostwick
Department of Mechanical Engineering
Clemson University

Elastocapillary Dynamics in Soft Gels

Soft gels are utilized in emerging applications, e.g. bioprinting, and are distinguished in that the forces of capillarity (surface tension) and elasticity are comparable in magnitude leading to elastocapillary phenomena including the observation of new analogous hydrodynamic instabilities in soft materials. This talk will provide a survey of our recent work in this area including gel drop oscillations in ultrasonic levitation, soft fracture, splash suppression, and droplet durotaxis. In each example, we highlight the multiphysics through the elastocapillary number and viscoelastic relaxation time scale. Of particular note is that our results can be used as novel diagnostic techniques to measure the surface tension and fracture energy of soft gels.

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Meeting ID: 213 798 950

Anuradha Gupta (Host)
Department of Physics and Astronomy
University of Mississippi

A Lecture Exploring Supermassive Black Holes

In this colloquium, we will watch a lecture exploring supermassive black holes, for which Andrea Ghez shared the 2020 Nobel Prize in Physics. The link to Andrea Ghez's talk can be found here.

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Meeting ID: 213 798 950

Karl Warburton
Department of Physics and Astronomy
Iowa State University

Machine Learning in Long-Baseline Neutrino Oscillation Experiments

Neutrinos, the most abundant massive particle in the Universe have profoundly influenced its evolution, but are still the least understood fermion in the Standard Model (SM). The 2015 Nobel Prize in Physics was awarded to T. Kajita and A. McDonald following numerous experimental observations of neutrino oscillations, the process by which neutrinos created in one flavor state are observed interacting as different flavor states after traveling a given distance. This colloquium will cover two experiments focused on furthering our understanding of this phenomenon. NOνA is the current flagship long-baseline neutrino experiment in the USA and consists of two functionally identical, finely granulated detectors that are separated by 809 km. The NOνA three flavor neutrino oscillation results presented in June 2020 will be discussed with particular focus given to the impact that machine learning algorithms had increasing the sensitivity of the analysis. These algorithms use topological features for the reconstruction of neutrino interaction flavor and particle identification. The colloquium will conclude with an exploration of how machine learning tools will inform the physics reach of DUNE, a planned long-baseline neutrino experiment, which will begin data-taking in the mid-2020s.

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Meeting ID: 919 282 27187

Deep Medhi
Department of Computer Science & Electrical Engineering
University of Missouri — Kansas City

Interdisciplinary Science: Connecting Physics, Computer Science and Statistics with Computer Networking

The image of a black hole from April 2019 was widely seen by millions of people all over the world. To make this happen, it transcended traditional boundaries of a scientific discipline. In this talk, I will discuss examples such as black hole imaging and Large Hadron Collider for high energy physics, and connect them with computer science and statistics, and how computer networking plays a role.

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Meeting ID: 919 282 27187

Katelin Schutz
Department of Physics
Massachusetts Institute of Technology

Making Dark Matter out of Light

Dark matter could be a “thermal-ish” relic of freeze-in, where the dark matter is produced by extremely feeble interactions with Standard Model particles dominantly at low temperatures. In this talk, I will discuss how sub-MeV dark matter can be made through freeze-in, accounting for a dominant channel where the dark matter gets produced by the decay of plasmons (photons that have an in-medium mass in the primordial plasma of our Universe). I will also explain how the resulting non-thermal dark matter velocity distribution can impact cosmological observables.

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Meeting ID: 919 282 27187

Mike Wallbank
Physics Department
University of Cincinnati
Searching for Sterile Neutrinos using Antineutrino Oscillations with the NOνA Experiment

The NOνA experiment consists of two functionally identical liquid scintillator detectors to study neutrino oscillations over an 810 km baseline using Fermilab's NuMI neutrino beam. In additional to world- leading studies of oscillations between the three known neutrino flavors, NOνA is searching for evidence of oscillations involving an additional, sterile, neutrino. Despite observations of neutrino oscillations from the majority of experiments being consistent with a 3-neutrino mixing framework, results from LSND and MiniBooNE are incompatible with this model but could be explained by incorporating a sterile neutrino state. These intriguing results are not conclusive and are in tension with findings from other short-baseline and long-baseline experiments.
I will describe the NOνA experiment and show the latest oscillation results, including a novel sterile search using antineutrinos, and discuss the allowed limits on the mixing angles governing the oscillations. I will also talk about future improvements to the oscillation analyses, in particular highlighting an ongoing test beam program designed to improve our understanding of the detectors and allow more precise analyses through a reduction of the uncertainties.

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Meeting ID: 919 282 27187

Carl Herickhoff
Biomedical Engineering
University of Memphis

New Directions in Ultrasound Imaging Technology

Ultrasound has become an established clinical imaging tool in recent decades due to its speed, safety, affordability, and portability, yet biomedical ultrasound technology continues to rapidly advance in new and exciting ways. This talk will give an introduction to ultrasound imaging systems and devices, while also highlighting some current fundamental and applied ultrasound research efforts: intravascular elasticity imaging, dual-frequency superharmonic contrast imaging, large-scale body scanner arrays, low-cost freehand 3D imaging, and integration with augmented-reality displays for live ultrasound image guidance.

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Meeting ID: 919 282 27187

Umberto Tamponi
Particle Physics Group
INFN — Torino and the University of Mississippi

Bottomonium at the Super-B factories: QCD and new physics

In the last 15 years, several experiments contributed to an explosion of new results on heavy QCD bound states. Today, we potentially stand at the beginning of a new wave of discoveries, with the Belle II experiment starting its data taking, BESIII moving forward into its program and the LHC experiments moving into their next phase. These new experiments, collecting much larger statistics, will not only allow to constrain the low energy QCD models, but also to study rare decays sensitive to new physics scenarios.

In this seminar, I will first outline the basic ideas and the status of the bottomonium physics, and then describe more in detail the potential of the measurement that will be performed at the Belle II experiment, ranging from the spectroscopy of the tetraquark-like states to the study of New-physics signatures in rare and forbidden decays.

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Meeting ID: 919 282 27187

Eugenio Bianchi
Institute for Gravitation and the Cosmos
Pennsylvania State University

Quantum Aspects of Black Hole Physics

I will discuss recent developments in black hole physics that are at the frontier of gravity, quantum field theory and quantum information. In particular I will discuss how thermal properties of black holes arise from energy eigenstates of the gravitational field in a manner similar to what happens in other isolated many-body quantum systems. I will also highlight how the observation of the statistical distribution of the spin of primordial black holes can provide the first observational test of black hole entropy.

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Meeting ID: 919 282 27187

Wanwei Wu
Neutrino Division
Fermi National Accelerator Laboratory

Liquid Argon Time Projection Chambers for Neutrino Physics

As the most abundant massive particles in our universe, neutrinos are elusive and provide a promising window to probe the fundamental physics. They are everywhere but almost never interact with matter. Questions about the nature of neutrinos and whether they are the reason that universe is made of matter rather than antimatter are still unanswered. One promising detector technology that can be used to study neutrinos in detail is the liquid argon time projection chamber (LArTPC), which has been adopted by many accelerator-based neutrino experiments including the Fermilab Short-Baseline Neutrino program and the Deep Underground Neutrino Experiment. LArTPCs promise to have millimeter-scale spatial resolution and excellent calorimetric capabilities in the detection of particles traversing the liquid argon and the measurement of their properties. In this talk, the landscape of LArTPCs for neutrino physics will be discussed, along with the prospects and status of the LArTPC neutrino experiments at Fermilab.

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Meeting ID: 919 282 27187

Lan Quynh Nguyen
Department of Physics
University of Notre Dame

Self Interacting Dark Matter and the Small-Scale Structure Problem

The core-cusp problem remains as a challenging discrepancy between observations and simulations in the standard CDM model for the formation of galaxies. The problem is that CDM simulations predict a steep power-law mass density profile at the center of galactic dark matter halos. However, observations of dwarf galaxies in the Local Group reveal a density profile consistent with a nearly flat distribution of dark matter near the center. A number of solutions to this dilemma have been proposed. Here, we summarize investigations into the possibility that the dark matter particles themselves self-interact and scatter. Such self-interacting dark matter (SIDM) particles can smooth out the dark-matter profile in high-density regions. We also review the theoretical proposal that self-interacting dark matter may arise as an additional Higgs scalar in the 3-3-1 extension of the standard model. We present new simulations of galaxy formation and evolution for this formulation of self-interacting dark matter. Current constraints on this self-interacting dark matter are then summarized.

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Meeting ID: 919 282 27187

Rachel Rosen
Department of Physics
Columbia University

Gravity Meets Particle Physics

Many of the most pressing open questions in fundamental physics today require a better understanding of the interplay between gravity and particle physics. In this talk, I will review what we learn by treating gravity as a theory of particle physics: what new theories emerge, what constraints they must obey, and what we might learn about gravitational phenomena such as black holes.

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Meeting ID: 919 282 27187

Christopher Berry
Center for Interdisciplinary Exploration and Research in Astrophysics
Northwestern University

The Secret Lives of Black Holes

Gravitational-wave astronomy provides a unique insight into the lives of black holes. Since the beginning of the advanced-detector era in September 2015, we have observed gravitational waves from over 40 binary black hole systems. From the measured gravitational-wave signal we can infer the properties of their source systems, and uncover new insights into their formation. There are currently many mysteries around how massive stars evolve and binaries form in order to create the population of binary black holes. I will explain how we can use the growing catalogue of gravitational-wave observations to unravel these mysteries and review our discoveries to date.

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Meeting ID: 919 282 27187

Paul Elmore
Applied Physics Laboratory (APL)
Johns Hopkins University

The Johns Hopkins University — Applied Physics Laboratory and the KTY Group & The Physics Career from the Mid-Career Perspective

This talk, intended for both undergraduate and graduate students, is dual purpose. The first part is a short recruitment talk on Johns Hopkins University — Applied Physics Laboratory and the Acoustics and Electromagnetics Group. The laboratory and group employ physics graduates at the Bachelor's, Master's and Ph.D. levels. The second part of this talk is centered on general advice for a career in physics. I will use my personal career path as an illustration of what, in my opinion (which is admittedly biased), are the biggest advantages of being a physicist vs an engineer or specialized physical scientist. These advantages are

A. Being a “generalist” in the physical sciences, which can provide flexibility in job opportunities and specialization choices in your early career

B. Formal training and general capability to solve hard analytic problems

There are trade-offs, of course (e.g., lack of specialization for jobs that require it, lack of training in engineering approaches, etc.), but the advantages can outweigh the trade-offs. In addition, this talk will provide some discussion for the following topics and time for Q&A:

• Whether or not to get your Ph.D. or perhaps enter the workforce at the Bachelor's or Master's degree level.
• The importance of publications and in structuring your publication for readability and information flow in order to enhance potential citation count.
• The importance of public speaking and going to conferences.
• A few bits of career “self-care” advice.

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Meeting ID: 919 282 27187

Meghna Bhattacharya
Department of Physics and Astronomy
University of Mississippi

First Results from the Muon g-2 Experiment at Fermilab — Muons Leading the Way

The first results from the Muon g-2 experiment at Fermilab will be presented in this talk. The latest result from the Fermilab confirms the discrepancy between the theoretical prediction and the experimental measurement earlier reported by the Brookhaven experiment. The aim of the Fermilab experiment is to measure the anomalous magnetic moment of the muon, a_μ = (g-2)/2, to a groundbreaking precision of 140 ppb, obtaining a near four-fold increase in precision over BNL. This is an incredibly challenging experiment with a unique opportunity to provide new insight into nature. An overview of this ultra-high precision measurement will be discussed in this talk.

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Meeting ID: 919 282 27187

Department of Physics and Astronomy
University of Mississippi

Research Poster Session

Despite the pandemic, student researchers in the Department of Physics and Astronomy have continued to do some excellent work. In the spirit of scientific discourse, we will be holding a research poster session tomorrow, Thursday April 22 at 4 pm in front of Lewis Hall. Please join us to hear about ongoing research in the department, and maybe get some ideas for a new project!

The web page can be found here.

Jake Bennett, etc.
Department of Physics and Astronomy
University of Mississippi

What can you do with a Physics degree?

Undeclared, interested in exploring other majors, or just curious about the Department of Physics and Astronomy? Want to prepare for professional school or just develop the tools and qualities employers value most? Join us to discover what a degree in Physics can do for you. You will also get the chance to observe some fun and interesting demonstrations.

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Meeting ID: 919 282 27187

Martin Frank
Department of Physics
University of South Alabama

First Results from NOνA's Magnetic Monopole Search

The existence of the magnetic monopole has eluded physicists for centuries. The NOνA far detector (FD), used for neutrino oscillation searches, also has the ability to identify slowly moving magnetic monopoles (v < c /100). With a surface area of 4,100 m² and a location near the earth's surface, the 14 kt FD provides us with the unique opportunity to be sensitive to potential low-mass monopoles unable to penetrate underground experiments. We have designed a novel data-driven triggering scheme that continuously searches the FD's live data for monopole-like patterns. At the offline level, the largest challenge in reconstructing monopoles is to reduce the 148,000 Hz speed-of-light cosmic ray background. In this talk, I will present the first results of the NOνA monopole search for slow monopoles.

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Meeting ID: 919 282 27187

Shawn Pollard
Department of Physics and Materials Science
University of Memphis

Designing Chiral Magnetism Through Interface Engineering – From Skyrmions to Magnetic Memory

Chirality is a fundamental concept in condensed matter physics. The ability to control magnetic chirality through broken symmetry at interfaces has led to the development of new devices governed by control of the local spin structure. One such structure, the skyrmion, a result of the Dzyaloshinskii-Moriya interaction (DMI), has been proposed as both a building block of new spintronic devices and as a tool to probe a variety of novel electrical transport phenomena. In this talk, I will describe our efforts to design chiral structures including skyrmions with tunable stability and dynamics by modifying the interface properties in both heavy metal/ferromagnet bi- and multilayers. We find that by tuning the heavy metal and ferromagnetic layer thicknesses and repetition numbers, we can control the skyrmion boundary structure, which has profound effects on its dynamics. This includes the first observation of an interlayer DMI in which a breaking of domain wall degeneracy can be used to prevent off-axial current driven skyrmion motion known as the skyrmion Hall effect. I also discuss our work developing new techniques in which to quantify magnetic phenomena in these materials.

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Meeting ID: 919 282 27187

Samrat Choudhury
Department of Mechanical Engineering
University of Mississippi

Machine Learning Enabled Multi-Scale Modeling of Materials

Traditional computational investigation of processing-chemistry-structure-property linkage in materials science involves the usage of specialized computational tools at discrete length scales ranging from electronic to atomic to mesoscale. Alternatively, over the past two decades, a multi-length scale approach combining simulation tools at different length scales has been adopted where electronic/atomic information from lower length scale is passed to higher length scale. However, such traditional computational approaches can provide only limited insights into a highly complex set of interactions spanning over multiple length and time scales each of which are linked to the property and performance of the materials, thus requiring an out-of-the box approach. In this presentation, I will focus on the application of machine learning tools to guide simulations at multiple length scales to augment the capabilities of traditional computational tools. Further, it will be shown that machine learning enabled computational approach provides a fast and efficient pathway to navigate the vast processing, microstructure and chemical search space for a targeted property, a departure from the traditional time consuming and expensive Edisonian trial-and-error approach based on synthesis-testing experimental cycles.

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Meeting ID: 919 282 27187

Jake Bennett, Gavin Davies, Anuradha Gupta, and John Waite
Department of Physics and Astronomy
University of Mississippi

Preparing for Job Interviews (including mock interview examples)

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Meeting ID: 919 282 27187

Sudeep Adhikari
Department of Physics and Astronomy
University of Mississippi

Universality in Activated Barrier Crossing

The thermal activation process by which a system passes from one local energy minimum to another by crossing an energy barrier is a recurring motif in physics, chemistry, and biology. For instance, biopolymer chains are typically modeled in terms of energy landscapes, with folded and unfolded configurations represented by two distinct wells separated by a barrier. The rate of transfer from the unfolded to folded state depends most importantly on the height of the barrier with respect to the temperature of the heat bath—but also in seemingly idiosyncratic ways on the details of the shape of the barrier. We consider the case of bias due to an external force, analogous to the pulling force applied in optical tweezer experiments on biopolymers. We identify the universal behavior of the barrier crossing process and demonstrate that data collapse onto a universal curve can be achieved for simulated data over a wide variety of energy landscapes having barriers of different heights and shapes.

John Waite
Department of Physics and Astronomy
University of Mississippi

Flavor SU(3) in Cabibbo-favored D-meson Decays

Model-independent description of nonleptonic decays of charmed mesons is a challenging task due to the large nonperturbative effects of strong interactions on the transition amplitudes. We discuss the equivalence of two different flavor-SU(3)-based descriptions of Cabibbo-favored non-leptonic decays of charmed mesons to two-pseudoscalars final states including the η and η′ mesons.

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Meeting ID: 919 282 27187

Zara Bagdasarian
Department of Physics
University of California — Berkeley

Reaching for the Stars with CNO Solar Neutrinos and Other Adventures of Novel Neutrino Detectors

The latest breakthrough in neutrino physics is the first experimental evidence of the carbon-nitrogen-oxygen (CNO) fusion cycle in the Sun. The discovery was possible due to the unprecedented radiopurity of the Borexino liquid-scintillator detector (Italy), employing innovative hardware and software developments. In the future, new technologies can further facilitate access to a broad physics agenda and applications in neutrino physics. Of particular interest are the cutting-edge detection techniques and novel target materials that aim to fully utilize both scintillation and Cherenkov signals from low- and high-energy neutrino interactions. The first deployment of Large Area Picosecond Photodetectors (LAPPDs) and water-based liquid scintillator (WbLS) in the ANNIE experiment at Fermi National Accelerator Laboratory (USA) will be exciting milestones in the evolution of neutrino detection. Neutrino Experiment One (NEO) will be the first ktonne-scale detector built by the Watchman collaboration at Boulby Underground Laboratory (UK). Its goal is to demonstrate, for the first time, nuclear non-proliferation capabilities using antineutrino detection. Finally, the multi-ktonne detector, Theia, aims to detect solar neutrinos, determine neutrino mass ordering and the CP-violating phase, observe diffuse supernova neutrinos and neutrinos from a supernova burst, search for nucleon decay, and, ultimately, neutrinoless double beta decay.

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Meeting ID: 919 282 27187

Zara Bagdasarian
Department of Physics
University of California — Berkeley

Reaching for the Stars with CNO Solar Neutrinos and Other Adventures of Novel Neutrino Detectors

The latest breakthrough in neutrino physics is the first experimental evidence of the carbon-nitrogen-oxygen (CNO) fusion cycle in the Sun. The discovery was possible due to the unprecedented radiopurity of the Borexino liquid-scintillator detector (Italy), employing innovative hardware and software developments. In the future, new technologies can further facilitate access to a broad physics agenda and applications in neutrino physics. Of particular interest are the cutting-edge detection techniques and novel target materials that aim to fully utilize both scintillation and Cherenkov signals from low- and high-energy neutrino interactions. The first deployment of Large Area Picosecond Photodetectors (LAPPDs) and water-based liquid scintillator (WbLS) in the ANNIE experiment at Fermi National Accelerator Laboratory (USA) will be exciting milestones in the evolution of neutrino detection. Neutrino Experiment One (NEO) will be the first ktonne-scale detector built by the Watchman collaboration at Boulby Underground Laboratory (UK). Its goal is to demonstrate, for the first time, nuclear non-proliferation capabilities using antineutrino detection. Finally, the multi-ktonne detector, Theia, aims to detect solar neutrinos, determine neutrino mass ordering and the CP-violating phase, observe diffuse supernova neutrinos and neutrinos from a supernova burst, search for nucleon decay, and, ultimately, neutrinoless double beta decay.

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Meeting ID: 919 282 27187

Alexandru Lupsasca
Department of Physics
Princeton

The Black Hole Photon Ring

The photon ring is a narrow ring-shaped feature, predicted by General Relativity but not yet observed, that appears on images of sources near a black hole. It is caused by extreme bending of light within a few Schwarzschild radii of the event horizon and provides a direct probe of the unstable bound photon orbits of the Kerr geometry. I will review the origin and structure of the photon ring, before discussing the prospects for its future detection. I will argue that the precise shape of the observable photon ring is remarkably insensitive to the astronomical source profile and can therefore be used as a stringent test of strong-field General Relativity. A space-based interferometry experiment targeting the photon ring of M87* could test the Kerr nature of the source to the sub-sub-percent level.

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Kathy Gunn
Department of Oceanography
Commonwealth Scientific and Industrial Research Organisation (Australia)

Vertical Mixing and Heat Fluxes Conditioned by a Seismically Imaged Oceanic Front

The southwest Atlantic gyre connects several distinct water masses, which means that this oceanic region is characterized by a complex frontal system and enhanced water mass modification. Despite its significance, the distribution and variability of vertical mixing rates have yet to be determined for this system. Specifically, potential conditioning of mixing rates by frontal structures, in this location and elsewhere, is poorly understood. Here, we analyze vertical seismic (i.e., acoustic) sections from a three-dimensional survey that straddles a major front along the northern portion of the Brazil-Falkland Confluence. Hydrographic analyses constrain the structure and properties of water masses. By spectrally analyzing seismic reflectivity, we calculate spatial and temporal distributions of the dissipation rate of turbulent kinetic energy, ε, of diapycnal mixing rate, K, and of vertical diffusive heat flux, FH. We show that estimates of ε, K, and FH are elevated compared to regional and global mean values. Notably, cross-sectional mean estimates vary little over a 6 week period whilst smaller scale thermohaline structures appear to have a spatially localized effect upon ε, K, and FH. In contrast, a mesoscale front modifies ε and K to a depth of 1 km, across a region of O(100) km. This front clearly enhances mixing rates, both adjacent to its surface outcrop and beneath the mixed layer, whilst also locally suppressing ε and K to a depth of 1 km. As a result, estimates of FH increase by a factor of two in the vicinity of the surface outcrop of the front. Our results yield estimates of ε, K and FH that can be attributed to identifiable thermohaline structures and they show that fronts can play a significant role in water mass modification to depths of 1 km.

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Saptaparna Bhattacharya
Department of Physics and Astronomy
Northwestern University

An Experimental Overview of Effective Field Theory Exploration at the LHC

The effective field theory (EFT) approach posits that in a scenario where new particles cannot be observed directly at low energy, the source of new physics are heavy fields beyond our current reach. The Standard Model (SM) Lagrangian contains fields of dimension-4 and the EFT frame-work extends the SM Lagrangian in an expansion in inverse powers of the scale of new physics. Within this framework, the potential impact of higher dimensional operators can be explored. The most common example of an EFT appears in the Fermi theory of weak interactions where the appearance of the four Fermi vertex features an operator of dimension-6. In this talk, I will provide an overview of EFT explorations at the LHC. With the collection of more than 150 fb^-1 of data at the LHC, rare processes predicted in the Standard Model have become accessible. These rare processes can be used as probes of new physics using the EFT framework. The large dataset also enables precision measurements of certain processes allowing the ability to study deviations from SM expectations and characterizing the nature of potential excesses within the EFT formalism. I will focus on the exploration of dimension-6 and dimension-8 operators at the LHC in final states arising out of the decay of multiple gauge bosons. I will provide a snapshot of LHC Run II analyses as we embark on Run III.

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Xinyue Gong
Department of Physics and Astronomy
University of Mississippi

Hall Effect for Acoustic Waves Carrying Angular Momentum

Acoustic waves with a twisted wave front also carry angular momentum in addition to linear momentum,in analogy to optical and quantum fields. The law of refraction states that the direction of refracted light rays is normally in the plane of incidence as they propagate across a sharp interface. Nevertheless, the refraction law is not enough to describe the angular momentum carried by refracted beams. Refracted light beams carrying angular momentum have been observed to undergo a shift in the direction that is transverse to the plane of incidence, a phenomenon that was termed as optical Hall effect. Here we pursue the first experimental observation of Hall effects for acoustic waves that carry angular momentum. Our experiment exploits the more recently developed acoustic metasurface to manipulate the wave refraction. A theoretical calculation of the wave fields is also conducted to compare with the experimental measurements. The talk will present physics related to the phenomenon, our experimental setup, and preliminary results.

Guoqin Liu
Department of Physics and Astronomy
University of Mississippi

Modeling and Simulations of Capillary-Gravity Wave Transmission Through a Surface Piercing Barrier

Capillary-gravity waves are waves traveling on a fluid interface that are influenced by both the effects of surface tension and gravity. Interactions of capillary-gravity waves with boundaries in contact with a solid and air play an essential role in both fluid physics and fluid control techniques. Motion of the contact line at the three phase boundary (solid, liquid, and air) can influence the wave dynamics such as the wave frequency, damping, refraction, and transmission. Here we develop fluid dynamics modeling and numerical simulations to investigate the transmission of capillary-gravity waves through a surface piercing barrier under the effect of a pinned contact line. Our modeling is validated via a comparison with prior theory in ideal cases. We numerically reveal how the surface tension and contact lines affect the transmission in the realistic case for waves of different frequencies and barriers of different depths.

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M. Mahbub Alam

Daffodil International University, Dhaka, Bangladesh
Effects of Viscosity on Effective Dynamic Properties

Recent theoretical and experimental findings demonstrate that as the particle concentration in a suspension increases, the effect of viscosity of the base fluid becomes more and more significant, thereby requiring to be taken into account when calculating effective properties of a suspension. Here, we employ a core-shell, self-consistent, effective medium model to derive analytical approximations for effective bulk-modulus and effective mass density for a suspension of solid elastic spheres. We incorporate the viscosity of the suspending fluid into the model through wave conversion phenomena, primarily between compressional and shear wave modes. The analytical approximations are explicit functions of particle volume fraction, dimensionless compressional and shear wave numbers, and scattering coefficients of a single sphere. The dependence of effective properties on frequency, particle size, volume fraction, and viscosity are also investigated numerically.

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Suravinda Kospalage
Department of Physics and Astronomy
University of Mississippi

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Dipangkar Dutta
Department of Physics and Astronomy
Mississippi State University

The Incredible Shrinking Proton and the Proton Radius Puzzle

For nearly half a century the charge radius of the proton had been obtained from measurements of the energy levels of the hydrogen atom or by scattering electrons from hydrogen atoms. Until recently the proton charge radius obtained from these two methods, agreed with one another within experimental uncertainties. In 2010 the proton charge radius was obtained for the first time by precisely measuring the energy levels of an exotic kind of hydrogen atom called muonic hydrogen. The charge radius of the proton obtained from muonic hydrogen was found to be significantly smaller than those obtained from regular hydrogen atoms. This was called the “proton charge radius puzzle” and led to a rush of experimental as well as theoretical efforts to understand whythe size of the proton appears to be different when measured in regular hydrogen vs. muonic hydrogen. Many physicists were excited by the possibility that the “puzzle” was an indication of a possible new force that acted differently on electrons and muons.

The Proton Charge Radius (PRad) experiment at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) was one such major new effort which used electron scattering from a regular hydrogen atom, but with several innovations that made it the highest precision electron scattering measurement. These innovative methods have allowed us to measure the size of the proton more precisely than it has been measured before using electron scattering. I will provide a brief review of the techniques used to measure the proton's size and introduce the “ proton radius puzzle”, and the world-wide effort to resolve this puzzle. I will discuss the PRad experiment, the new results from this experiment, the current status of the “puzzle” and future prospects.

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Katerina Chatziioannou
Division of Physics, Mathematics and Astronomy
California Institute of Technology

Constraining the Neutron Star Equation of State with Gravitational Wave Signals

Detections of neutron stars in binaries through gravitational waves offer a novel way to probe the properties of extremely dense matter. In this talk I will describe the properties of the signals we have observed, what they have already taught us, and what we expect to learn in the future. I will also discuss how information from gravitational waves can be combined and compared against other astrophysical and terrestrial probes of neutron star matter to unveil to the properties of the most dense material objects that we know of.

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Stefano Tognini
Nuclear Energy and Fuel Cycle Division
Oak Ridge National Laboratory

Celeritas: Bringing Exascale Computing to HEP Detector Simulation

Within the next decade experimental High Energy Physics (HEP) will (mostly) finish building its next generation of particle detectors. This includes upgrades to the Large Hadron Collider and its main experiments, and completing the Deep Underground Neutrino Experiment (DUNE). This new Era brings a myriad of challenges, many being on the computational front. As DOE consolidates its network of Leadership Computing Facilities (LCFs) with supercomputers capable of reaching Exaflops of processing power, it is fundamental to better integrate these LCFs with HEP computing workflows. In this talk I will provide an overview of computing in HEP and its many challenges, and present Celeritas, a novel GPU Monte Carlo particle transport code developed by researchers from ORNL, Fermilab, ANL, and BNL, that aims to close the gap between DOE's LCFs and HEP experiments.

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Biswaranjan Behera
Department of Physics
Colorado State University

The Search for Sterile Neutrinos with the ICARUS Detector at Fermilab

The 476-ton active mass ICARUS T-600 liquid Argon Time Projection Chamber (LArTPC) was a pioneering development that became the template for neutrino and rare event detectors, including the massive next generation international Deep Underground Neutrino Experiment. It began operation in 2010 at the underground Gran Sasso National Laboratories and was transported to Fermilab in the US in 2017. To ameliorate the impact of shallow depth operation at Fermilab, the detector was enhanced with the addition of a new high granularity light detection system inside the LAr volume and an external cosmic ray tagging system. Currently in the final stages of commissioning, ICARUS is the largest LArTPC ever to operate in a neutrino beam. In this talk I will describe how ICARUS will resolve a long-standing neutrino anomaly that favors the existence of a new, non-interacting, "sterile" neutrino.

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Erika Hamden
Department of Astronomy and Steward Observatory
University of Arizona

Building Your Own Ultraviolet Telescope

Why do galaxies look the way they do? How do galaxies interact with their environments? How does a star form? How does the environment around a new star impact the planets that form around it? These questions can all be answered by observations in the ultraviolet, a seriously neglected wavelength range. In this talk, I will discuss several space and sub-orbital UV telescopes that I am developing to answer the questions above, including FIREBall-2 (a balloon-borne UV spectrograph), Aspera (a NASA funded extreme UV SmallSat), and Hyperion (a FUV mission in development). I will also describe the importance of technology development in enabling these missions and the science they can achieve. Finally, I will argue that the best way to answer difficult science questions is to stop waiting for someone else to build your telescope.

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Zhenhua Tian
Department of Aerospace Engineering
Mississippi State University

Leveraging Acoustics for Structural Health Monitoring and Noncontact Manipulation of Micro/Nano Objects

Acoustic waves carry both information and energy that allow them to inspect material defects as well as create invisible robotic hands (i.e., acoustic tweezers) capable of manipulating matter. This talk will cover my previous studies on leveraging acoustics for structural health monitoring (SHM) and noncontact manipulation of micro/nanoparticles. The first part of the talk is about SHM systems based on laser ultrasonics and ultrasonic arrays for rapid inspection of defects in aerospace structures, such as delamination in composites, disbonding in honeycomb sandwich panels, and corrosion in metal plates. The second part of my talk focuses on dynamic acoustic tweezers based on 10's MHz surface acoustic waves (SAWs). These SAW-based acoustic tweezers use a programmable array of interdigital transducers (IDTs) for the translation, patterning, and concentration of micro/nano objects. Their functions will be discussed with experimental examples, including (i) constructing diverse lattice-like patterns of micro/nanoparticles, (ii) manufacturing composites with patterned carbon nanotubes, and (iii) printing anisotropic tissues with aligned cells.

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Prajwal Mohan Murthy
Department of Physics
University of Chicago

Search for the Neutron Electric Dipole Moment and "what next?"

Baryon asymmetry of the universe, i.e. the fact that much of the observed universe is made of matter as opposed to equal amounts of matter and anti-matter, demands violation of Charge-Parity (CP) symmetry. Yet, the amount of CP violation from the Standard Model of particle physics is insufficient to explain the baryon asymmetry of the universe. Observation of a non-zero permanent electric dipole moment (EDM) coupled to the spin of any sub-atomic particle, such as the neutron, is an indication of CP violation. Therefore, measuring the neutron EDM, is a key technique of getting a handle on the amount of CP violation. The neutron EDM from the standard model sources is so small that no experiment has thus far achieved the sensitivity required. Nonetheless, searches for the neutron EDM is an important method by which to test and constrain physics beyond the standard model. The neutron EDM has been measured since the 1940s and the sensitivity of the experiments has improved by over 8 orders of magnitude.

The most recent series of efforts were conducted at the Paul Scherrer Institute (PSI). This was a room temperature experiment employing the Ramsey technique of separated oscillating fields. These measurements used a 21 l storage chamber, in which ultracold neutrons were stored, and surrounded by 4 layers of mu-metal. Prior to 2006, the series of measurements at the Institut Laue-Langevin (ILL) culminated in the measurement of d_n < 3 × 10^-26 e.cm (90% C.L) [Phys. Rev. D 92, 092003 (2015)] over 5 years of data taking. The ILL apparatus was upgraded significantly with addition of: (i) 16 Cs-133 magnetometers to further characterize the magnetic field environment in the storage chamber, (ii) a new neutron detector system which could simultaneously count both the spin states of the neutron, and (iii) optimized coating inside the storage chamber to maximize the neutron density. The upgraded apparatus was moved to the Paul Scherrer Institute and independently achieved a measurement of d_n < 1.8 × 10^-26 e.cm (90% C.L) [Phys. Rev. Lett. 124, 081803 (2020)] in just 2 years of data taking. The PSI nEDM experiment has also been a source of rich physics program beyond the measurement of the nEDM. It has investigated neutron oscillation, provided input into neutron lifetime measurements, searched for axions, and tested Lorentz Invariance.

While the search for CPV EDM was first attempted in neutrons, searching for atomic EDM may be a more lucrative avenue, since multiple sources contribute to an atomic EDM, viz. nucleon EDM, nuclear Schiff moment, CP violating interactions between the electrons and the nuclei, and the nuclear MQM also contributes to the atomic EDM. Nuclear Schiff moment and nuclear MQM are significantly enhanced in quadrupole and octupole deformed nuclei. We will also discuss viable candidate isotopes which have maximally enhanced sensitivity to EDMs.

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Department of Physics and Astronomy
University of Mississippi

Research Poster Session

Despite the pandemic, student researchers in the Department of Physics and Astronomy have continued to do some excellent work. In the spirit of scientific discourse, we will be holding a research poster session tomorrow, Thursday April 21 at 4 pm in front of Lewis Hall. Please join us to hear about ongoing research in the department, and maybe get some ideas for a new project!

The web page can be found here.

Vojtech Witzany
School of Mathematics and Statistics
University College Dublin

Action-angle Coordinates for Black Hole Geodesics

Action-angle (AA) coordinates are a traditional tool in celestial mechanics with roots as early as in the works of Johannes Kepler in 1609. In modern terms, AA coordinates amount to a particular spectral solution of the equations of motion of a given conservative system. As a result, they serve as an extremely convenient basis for further analytical computations. I will show how AA coordinates are constructed for black hole geodesics, and how that will be useful in various approximations to the relativistic two-body problem and binary inspirals (EOB, large mass ratio,...).

Hartmut Grote
Gravity Exploration Institute
Cardiff University

Quantum-Enhanced Interferometry for Dark Matter and Quantum Gravity Searches

Laser interferometry has revolutionized astronomy by introducing a new sense in the observation of the universe. We can now hear the ripples of space-time: gravitational waves. Moving beyond this 'application' of laser interferometry, in this talk I will give an overview of how ultra-precise laser interferometers can also be used to try to shed light on other mysteries of the universe. Namely the search for dark matter and the question of whether space-time is quantized at the smallest level.

Joe Rivest, Madusanka Abeykoon, Devesh Bhattarai
Department of Physics and Astronomy
University of Mississippi

Student Research Presentations

Graduate students in the Department of Physics and Astronomy will present brief reports on their ongoing research.

Sina Rostami, Santosh Bhandari, Quinn Campagna
Department of Physics and Astronomy
University of Mississippi

Student Research Presentations

Graduate students in the Department of Physics and Astronomy will present brief reports on their ongoing research.

Cecille Labuda
Department of Physics and Astronomy
University of Mississippi

Spatial Variation of the Ultrasonic Properties of Brain

Brain is inhomogeneous due to its composition of different tissue types (gray and white matter), anatomical structures (e.g. thalamus and cerebellum), and cavities in the brain (ventricles). These inhomogeneities lead to spatial variations in the ultrasonic properties of the organ. However, reporting on the spatial variation of the ultrasonic properties is limited in the literature. The spatial variation of the speed of sound, frequency slope of attenuation, attenuation and backscatter in brain tissue are presented here as two-dimensional maps. Tissue specimens were 1-cm thick slices of fixed sheep brain prepared from the coronal, sagittal and transverse anatomic planes. Ultrasonic measurements were performed using broadband transducers with center frequencies of 3.5, 5.0, 7.5, and 10 MHz. The spatial variation of these properties are clearly visualized and structures visible in the maps are consistent with the known morphologic features of the brain. White and gray matter appeared to be distinguishable in the images. The average values of the ultrasonic properties are consistent with published values.

There will be refreshments at 3:45 pm in Lewis 109.

Jeffrey Kleykamp and Luiz Prais
Department of Physics and Astronomy
University of Mississippi

Search for Non-Standard Interactions with Neutrino Oscillations at the NOvA Experiment

The phenomenon of neutrino oscillations provided the first evidence for the so-called Physics Beyond the Standard Model, and opened a window for several and interesting new investigations in the field of neutrino physics. Among the possibilities, Non-standard interactions (NSI) are an extension of the neutrino matter effect leading to a rich phenomenology, and are expected to modify the propagation of neutrinos through matter. The current open questions in the neutrino oscillation model rely heavily on how neutrinos interact with matter, to an extent that NSI could induce possible effects. The NOvA Experiment presents its first preliminary search for flavor-changing NSI in neutrino oscillations in the 810 km baseline as neutrinos cross the Earth's crust between the Near and Far Detectors.

There will be refreshments at 3:45 pm in Lewis 109.

Sadia Khalil
Senior Data Scientist
Caterpiller, Inc.

From Physicist to a Data Scientist: It's Never Too Late!

I am a senior data scientist at Caterpillar Inc, and I like to share my story of career transformation in the industry after more than a decade of research in the LHC experiments at the CERN. I like to tell you why a data scientist career is a highly desired profession for people with a STEM background, especially in Physics. I like to give some tips on how to build a professional network and a well-composed resume, coding techniques, soft skills, and a strong knowledge of the fundamentals of statistics.

There will be refreshments at 3:45 pm in Lewis 109. —

Michael Schatz
School of Physics and Center for Nonlinear Science
Georgia Institute of Technology

Forecasting Turbulence

Fluid turbulence is one of the greatest unsolved problems of classical physics (and the subject of a million dollar mathematical (Millenium) challenge). Centuries of research--including Leonardo da Vinci's observations of "la turbolenza" and the best efforts of numerous scientists (Heisenberg, Kelvin, Rayleigh, Sommerfeld, ...)--have failed to yield a tractable predictive theory. However, recent theoretical and computational advances have successfully linked recurring transient patterns (coherent structures) within turbulence to unstable solutions of the equations governing fluid flow (the Navier-Stokes equations). The solutions describing coherent structures provide a geometrical structure that guides the evolution of turbulence. We describe laboratory experiments where the geometry of key coherent structures is identified, thereby provided building blocks for describing the behavior of weakly turbulent flows.

There will be refreshments at 3:45 pm in Lewis 104. —

Alumni panel
Department of Physics and Astronomy graduates

Alumni Panel

Graduates of the University of Mississippi Department of Physics and Astronomy will discuss their career path following graduation, discuss some of the benefits that their degree brought them, and answer questions posed by students in attendance.