# SPACS Fall 2012 Colloquium Schedule

Colloquia are held Thursdays at 3:00 pm in Research Hall room 163 (except as noted below). To access previous Physics and Astronomy Colloquia, go here.

The talk on Sept 17 is being cosponsored with the Krasnow Institute – it is the only talk to meet on a Monday at 3PM in the Krasnow building.

### View all talk abstracts below table or click on talk title for individual ones.

Map and Directions ………………………….Physics 703 Syllabus

 Date Speaker Institution Title and Abstract Link if available 30 Aug — JC 325 Karen Sauer GMU Training spin for low-field magnetic resonance 6 Sept Michael Summers GMU Commercial Space Exploration: Opportunities for Research and Education 13 Sept Ernest Barreto GMU A Novel Mechanism for Neuronal Bursting and Seizing 17 Sept (Mon) in Krasnow Phillip Rubin GMU Wherefrom a Higgs? 20 Sept — JC 325 Jessica Rosenberg GMU Gas and Stars in Galaxies and their Environments: Clues to Galaxy Evolution 27 Sept— JC 325 Ming Tian GMU Magnetic nanostructures 4 Oct Makenzie Lystrup AAAS Science & Congress: A scientist’s perspective from inside the House of Representatives 11 Oct— JC 325 Krishna Vemuru GMU Chiral superfluid states in graphene heterostructures 18 Oct Eugenie Mielczarek& Brian Engler GMU Science policy at the intersection of physics, biology and medicine — some startling concepts 25 Oct Crystal Bailey American Phys Society Breaking The Myth of the “Non-Traditional” Physicist: The Real Story About Employment for Physics and Astronomy PhDs 1 Nov Stephen Lockett Nat’l Cancer Institute Spatial Organization in Cells and Nuclei 8 Nov Enrico Rossi College of Wm  & Mary Solid-State Rare-Earth Ensemble and Applications in Quantum Information 15 Nov TBA TBA 22 Nov Thanksgiving No colloquium 29 Nov Robert Ehrlich GMU The tachyonic neutrino hypothesis: Searching for tachyons or unicorns? 6 Dec Ulrich Jentschura Missouri U of Sci & Tech Generalized Dirac Equations and Tachyonic Neutrinos

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 bilayerheterostructures 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: A study of twenty years (1992-2012) worth of federal funding for alternative medicine:  What have we learned?

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.

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.