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
Largescale interferometric detectors including LIGO and Virgo sense gravitational waves; minuscule fluctuations in spacetime 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 multimessenger astronomy that confirmed the association between neutron star collisions and short gammaray
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 corecollapse 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 CPViolation 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 chargeparity (CP) symmetry, meaning the weak force interacts differently with
matter and antimatter. This last property may hold the key to understanding several fundamental mysteries of the universe from the
threegeneration 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 CPviolation. The nextgeneration 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 ShortBaseline 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 labonachip 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
labonachip 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 cellcell communications to 3D bioprinting, from circulating tumor cell isolation and detection to ultrahighthroughput blood
cell separation for therapeutics, from highprecision microflow cytometry to portable yet powerful fluid manipulation systems. These
acoustofluidic technologies are capable of delivering highprecision, highthroughput, and highefficiency cell/particle/fluid manipulation in a
simple, inexpensive, cellphonesized 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
Fluidfilled particles play a pivotal role in biomedical applications of ultrasound. This talk will cover two examples, lipidcoated
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
surfaceactive 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 lipidcoated microbubbles, we have studied this nonlinear behavior, including pressuredependent 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
ultrasoundmediated ablation more efficient. These studies provide insight into the unique nonlinear behavior of these fluidfilled 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 lowrank matrix factorization and multidimensional 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 nonmetric
multidimensional scaling provide a new perspective on the HawkingMalament 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
Department of Physics and Astronomy
University of Mississippi
Manifoldlikeness of Causal Sets
We study the distribution of maximalchain 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 2dimensional case and derive expressions for the expected number nk of maximal chains as a function of
their length k, the most probable maximalchain length k_{0}, 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 k_{0} 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 k_{0} and Δ, and end with a few simple examples of nk distributions for nonmanifoldlike causal sets.

Vishal Baibhav
Department of Physics and Astronomy
University of Mississippi
Systematic Errors and Energy Estimates in Binary Black Hole Ringdown
High signaltonoise 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 stateoftheart 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 alignedspin
binaries, and we produced postNewtonian inspired fits of the resulting energy estimates. 
Shrobana Ghosh
Department of Physics and Astronomy
University of Mississippi
Detectability of Gravitational Radiation from Superradiant Instabilities
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 nonaxisymmetric 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 groundbased or spacebased
gravitational wave detectors, depending on the mass of the boson. Based on astrophysical models we show that adLIGO should see 10^{4}
events in a 4 year mission for a scalar field mass of 3×10^{12} eV, while LISA will see about 10^{3} 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 groundbased 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 nontrivial 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
Department of Physics and Astronomy
University of Mississippi
Sound Speed Profiles of the Global Ocean calculated from Physical Oceanographic Data
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 (eastwest) and meridional (northsouth) coasttocoast 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.

Khagendra Adhikari
Department of Physics and Astronomy
University of Mississippi
Deforming the Fredkin Spin Chain Away from its Frustrationfree Point
The Fredkin model describes a spinhalf chain segment subject to threebody, correlatedexchange interactions and twisted boundary conditions.
The model is frustrationfree, and its ground state wave function is known exactly. Its lowenergy 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 lowlying states, using exact diagonalization and densitymatrix renormalization group calculations, in order to track the properties of
the system as it is tuned away from the Fredkin point. We identify a zerotemperature 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 “antiFredkin” point at which all the contributing spin configurations have a spin structure exactly
opposite to those in the Fredkin ground state.

Xudong Fan
Department of Physics and Astronomy
University of Mississippi
Enhancing Sound Emission by Using Subwavelength Metacavities
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 metacavities 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
metacavity offers a practical path toward miniaturization in applications that demand efficient emission, such as sonar, loudspeakers, or
ultrasound transducers.

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 strongfield 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 strongfield 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 Gravitationalwave 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. Strongfield 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 highenergy physics and strongfield 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 gravitationalwave detectors, and the
theoretical and observational challenges associated with their search. I will also discuss the potential of Earth and spacebased detectors to
further our understanding of the formation and evolution of compact binaries.
