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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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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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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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Charles F. Caskey>
Institute of Imaging Science
Vanderbilt University
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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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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