|
School of
Physics, Astronomy, and Computational Sciences Colloquia
for 2012-2013 Academic Year Coordinators:
Fall 2012 – R. Ehrlich, Spring 2013 – E. Zhao & M.
Tian |
Colloquia are held Thursdays at 3:00 pm in Research I room 163 (except
as noted below). The talk on Sept 17 is being cosponsored with the Krasnow
Institute – it is the only talk to meet on a Monday at 4PM in the Krasnow building. Map and Directions Physics 703 Syllabus Last
year’s Colloquia
Date |
Speaker |
Institution |
Title and Abstract Link if
available |
30
Aug -- JC 325 |
Karen
Sauer |
GMU |
|
6 Sept
– Res Hall 163 |
Michael
Summers |
GMU |
Commercial
Space Exploration: Opportunities for Research and Education |
13
Sept – Res Hall 163 |
Ernest
Barreto |
GMU |
|
17
Sept (Mon 4PM) in Krasnow
Great Hall |
Phillip
Rubin |
GMU |
|
20
Sept -- JC 325 |
Jessica
Rosenberg |
GMU |
Gas and Stars in Galaxies and their
Environments: Clues to |
27
Sept-- JC 325 |
Ming
Tian |
GMU |
Solid-State
Rare-Earth Ensemble and Applications in Quantum Information |
4
Oct |
Makenzie Lystrup |
AAAS |
Science &
Congress: A scientist's perspective from inside the House of Representatives |
11
Oct-- JC 325 |
Krishna
Vemuru |
GMU |
|
18
Oct – Res Hall 163 |
Eugenie
Mielczarek &
Brian Engler |
GMU |
Science
policy at the intersection of physics, biology and medicine -- some startling
concepts |
25
Oct – Res Hall 163 |
Crystal
Bailey |
American
Phys Society |
|
Oct 29 (Mon) Res 161 (not 163) |
A.
K. Drukier |
||
1
Nov – Res Hall 163 |
Stephen
Lockett |
Nat’l
Cancer Institute |
|
8
Nov – Res Hall 163 |
Enrico Rossi |
College of Wm & Mary |
|
15
Nov |
Ilsang Yoon |
GMU |
|
22
Nov |
Thanksgiving |
No colloquium |
|
29
Nov – Res Hall 163 |
Robert
Ehrlich |
GMU |
The tachyonic neutrino hypothesis: Searching for tachyons or
unicorns? |
6
Dec – Res Hall 163 |
Ulrich
Jentschura |
Missouri
U of Sci & Tech |
Sauer abstract: Magnetic
resonance enables the ready identification and characterization of matter;
low-field magnetic resonance pushes this capability into the field for
widespread use. Potential applications
are numerous – oil exploration, security checkpoints, pharmaceutical
diagnostics, etc. My research explores
how to harness spin dynamics at low fields to boost signal, gain new insight
into nuclear interactions in materials, and improve detection sensitivity with
the introduction of a radio-frequency quantum magnetometer. In this talk, I focus on optical-magnetic
feedback for precision control of spin-dynamics and quantum noise in atomic magnetometry.
Summers abstract: During the past
few years we have witnessed an exponentially growing interest in the
commercialization of space. With a
foundation of new technologies, dramatically lower costs, and prospects for
frequent (even daily) manned space flights, several commercial organizations
are developing the next generation of reusable space vehicles that will disrupt
the prevailing “big mission” paradigm of space exploration. The opportunities for research and education
are far-reaching. This nest generation
of space vehicles will provide new platforms for research in areas including
space medicine, microgravity studies, atmospheric science, remote sensing,
space physics, solar physics, astrophysics, among many others. The educational opportunities are equally
intriguing. Every university in the world can have its own space program. For the amount of money a group of students
can earn with a car wash, they can fly a space experiment and
get results back in time for a semester final report. In this talk I will discuss this new industry
and a few of the many possibilities for research and education.
Barreto abstract: It is
well-known that when a neuron fires an action potential, sodium and potassium
ions cross the neuron’s membrane. This process was
described quantitatively by Hodgkin and Huxley in the 1950s. But shouldn’t this
flow of ions affect the ion concentrations inside and outside the cell? If so,
how would this affect the behavior of the neuron? I will describe recent
computational studies that address these questions and raise new ones. Insights
from bifurcation theory lead to
the identification of a common mechanism that underlies several very different
neuronal behaviors which have been seen in many different experimental
settings.
Rubin abstract: The
story of a Higgs from the Standard Model and a discovery at CERN which looks a
bit like it.
Rosenberg abstract: Understanding the processes that drive the formation and evolution of galaxies is central to extragalactic astronomy. The mergers of galaxies, accretion and outflow of gas, and formation of stars are the dynamical mechanisms that drive the evolution of these systems over cosmic time. We observe snapshots of these processes in the properties of the gas and stars in and around galaxies. I will begin by discussing a large optical and HI 21 cm study to assess the gaseous and stellar components of nearby galaxies and what we are learning from it about the nature of galaxies in the local universe and their evolution. I will also talk about what we have learned about the gaseous environments of galaxies through absorption line studies and what that might tell us about the connection between evolutionary processes in galaxies and the larger scale intergalactic medium.
Ming
abstract: Solid-State Rare-Earth Ensemble forms a group of materials
important for applications in quantum information science and technology. On
one hand, rare-earth ions trapped in crystal lattice, such as yttrium aluminum
garnet, exhibits interesting energy structures and optical properties due to
various interactions of the rare-earth ions and the ions in the host lattice.
These properties and interactions can be studied through optical excitation
using laser pulses. On the other hand, this group of materials holds unique
potentials for implementation of critical components for quantum computation
and quantum communication. Related work at GMU will be presented in this talk
with the emphasis on robust universal quantum logic gates using optically
controlled geometric phase and the high efficiency quantum memory.
Lystrup abstract:
The
American Association for the Advancement of Science (AAAS) states that “The
science and engineering challenges that society faces today-locally, nationally
and internationally-are far more complex than were those of 40 to 50 years ago.
The problems now are more difficult to define and the solutions more difficult
to identify and implement. The best available scientific, technical and
economic information is required to establish priorities, make decisions, and
develop best policies and practices. Yet, scientists often lack the skills and
opportunity to apply their science successfully to support policy or to
communicate effectively with the public and other non-academic audiences. Consequently,
society's needs for the most credible and objective scientific information are
not being met.” To address these challenges, The AAAS manages and administers
Science & Technology Policy Fellowships that place scientists in Congress
for one year. Makenzie
Lystrup, a Fellow just finishing her tenure as a
Fellow, will share experiences and reflections on the 112th
Congress, effects on science R&D in terms of budget and other policy, and a
look forward toward the 113th Congress. Some of the questions that
will be addressed: How can we be better advocates for our science? Is the
scientific community just another special interest group? How can we
communicate more effectively with decision makers?
Rossi abstract: The chiral nature of the fermionic excitations in graphene, bilayer graphene, and topological insulators, induces unique electronic properties in these materials. In bilayer heterostructures the interlayer interaction can induce the formation of an interlayer phase coherent state. An interesting class of heterostructures is constituted by bilayers in which the electrons in the two layers have different chirality. An example of such a system that can be realized experimentally is the heterostructure formed by single layer graphene and bilayer graphene. In this talk I will discuss the conditions for the realization of an interlayer phase-coherent state in chiral-asymmetric heterostructures. In particular I will show how the voltage difference between the two layers affects the conditions for the realization of the phase coherent state, and its
properties. I will then discuss the relevance for experiments of our results.
Mielczarek abstract: Ignorance of science regarding concepts of energy, fields, and the laws of thermodynamics have driven funding in health care research. We will focus on these concepts and our research on NIH NCCAM grants that impart a veneer of respectability onto unproven Alternative Medicine protocols.
Bailey abstract: Physics
PhDs are among the most employable in the world, often doing everything from
managing a research lab at a multi-million dollar corporation, to developing
solutions to global problems in their own small startups. Science and
Technology employers know that with a physics training, a potential hire has
acquired a broad problem-solving skill set that translates to almost any
environment, as well as an ability to be self-guided and -motivated so that
they can teach themselves whatever is needed to be successful at achieving
their goals. Therefore it’s no surprise that the majority of PhD
graduates find employment in private-sector, industrial settings. At the same
time, only about 25% of graduating PhDs will take a permanent faculty
position--yet academic careers are usually the only track to which students are
exposed while earning their degrees.
Lockett
abstract: The spatial organization of molecules inside cells controls
biological processes, and it is hypothesized that direct alteration of spatial
organization through physical shape changes to cells can drive biological
processes. The Optical Microscopy and Analysis Laboratory (OMAL) is
pursuing two projects on this topic. The first project, which is in
collaboration with the Mouse Cancer Genetics Program and the Molecular Targets
Laboratory in Frederick, utilizes micropatterns to
force cells to grow in pre-defined shapes. We compared two malignant
peripheral neural sheet tumor (MPNST) cell lines that have different
proliferation rates but look similar in standard cell culture. By micropatterning, we discovered quantitative differences
between the two lines in terms of the curvature of their cell edges, leading us
to ask whether there is a functional relationship between membrane tension and
cell growth rate. The second project, in collaboration with Dr. Tom Misteli (NCI Bethesda), is to develop a high
throughput screen for breast cancer based on changes in the degree of
centeredness of DNA sequences of specific genes in cell nuclei. The main
challenge is automatic identification of accurately delineated nuclei within
intact tissue for gene centeredness measurement.
Vemuru abstract: Synthesis and characterization of magnetic nanostructures is an important aspect of research in nanoscience. In order to improve the characteristics of nanomaterials based devices, it is important to understand the structure property relation as well as the mechanism of the magnetic ordering. In this talk, I will introduce magnetic nanostructured materials with applications in high density magnetic data storage. Some of these are rodlike metallic iron and g-Fe2O3 nanoparticles, PZT thin films with Co nanostructures, FeRhPd/Co thin films, core-shell structured FePt, FePtCu, and FePtAu nanoparticles. I will present the details of the nanostructural characterization using small angle neutron scattering, and the element specific magnetic moment determination using x-ray magnetic circular dichroism spectroscopy.
Yoon abstract: Parametric approach to measure the galaxy morphological structure suffers from systematic and random errors owing to the characteristics of chosen model and data which are difficult to include in inference of galaxy morphology distribution. In this talk, I will introduce a Bayesian MCMC approach, fully considering the posterior probability for parameter estimation and model inference. Important issues in galaxy image decomposition, which are often neglected in conventional analysis methods, will be highlighted and significant improvements in parameter estimation and model inference will be shown by using an ensemble of simulated and real 2MASS galaxy samples.
Ehrlich abstract: With a recent
claim of superluminal neutrinos shown to be in error, 2012 may not be a
propitious time to consider the evidence that one or more neutrinos may indeed
be tachyons. Nevertheless, there are a growing number of observations that
continue to suggest this possibility -- albeit with an $m_{\nu}^2<0$ having
a much smaller magnitude than was implied by the original OPERA claim. In
addition to summarizing this evidence, this paper also discusses a 3 + 3 mirror
neutrino model incorporating one superluminal active-sterile neutrino pair, as
well as a large number and variety of tests of the superluminal neutrino
hypothesis, including a surprising prediction about an unpublished aspect of
the SN 1987 A neutrinos. See paper at: http://arxiv.org/pdf/1204.0484.pdf
Jentschura
abstract: In
1943, Wolfgang Pauli wrote an article for the Reviews of Modern Physics in
which he argued that the Hermiticity requirement for
quantum mechanical Hamiltonians can be relaxed and generalized to a weaker
requirement, that of so-called pseudo-Hermiticity.
All of the concepts introduced by Pauli into theoretical physics have found
deep and far-reaching applications --- except this one, up and until recently.
Using pseudo-Hermiticity, or PT symmetry, it has been
possible not only to solve a number of fundamental problems in mathematical physics,
but also, to describe quite interesting quantum optical phenomena in a concise
and transparent formulation. This talk will be focused on pseudo-Hermitian generalizations of the Dirac equation, which is a
first-order differential equation acting on four-dimensional spinor space. A theory of the neutrino based on a
generalized Dirac equation has a number of desirable properties: it suppresses
the right-handed neutrino, and left-handed anti-neutrino state due to negative
norm, conserves the concept of lepton
number, and allows for plane traveling-wave solutions. By contrast, a Majorana neutrino would force us to abandon the concept of
lepton number altogether, and the Majorana equation
does not allow for traveling-wave solutions in first quantization. The
emergence of massive neutrinos forces us to re-think basic concepts of the
standard model, which originally called for massless
(Weyl) neutrinos. The theoretical description of a
massive neutrino provides for much greater challenges
than a massless neutrino.