Physics Commons^™

On The Time-Resolved Optogalvanic Spectra Of Neon And Krypton, Naveed Piracha, K. Nesbett, S. Moten, P. Moeller

Naveed K. Piracha

In this work time resolved optogalvanic signals associated with transitions excited from the first metastable state of neon and krypton have been studied. These gases have similar energy state configurations and it is of significant interest to study their time resolved optogalvanic waveforms resulting from transitions belonging to the states of same quantum numbers. The experimentally observed optogalvanic signals recorded for different discharge currents have been fitted to a theoretical model to obtain parameters that determine amplitudes, instrumental time constants and decay rates of the 1s levels.

Spin Effects In The Effective Quantum Field Theory Of General Relativity, A Ross, Br Holstein

Barry R Holstein

The calculation of gravitational scattering of particles with various spin configurations in the framework of effective quantum field theory of general relativity is presented. We find that the long-range quantum and classical corrections to the spin-independent piece and the spin–orbit coupling piece of the scattering amplitude and the scattering potential are universal for different spin configurations, which leads us to propose this universality to be true for arbitrary spins. Furthermore, we give the leading corrections to the spin–spin coupling, and a comparison with scattering in QED is made.

Director Dynamics In Liquid-Crystal Physical Gels, Rafael Verduzco, Neal R. Scruggs, Samuel Sprunt, Peter Palffy-Muhoray, Julia A. Kornfield

Peter Palffy-Muhoray

Nematic liquid- crystal (LC) elastomers and gels have a rubbery polymer network coupled to the nematic director. While LC elastomers show a single, non- hydrodynamic relaxation mode, dynamic light- scattering studies of self- assembled liquid- crystal gels reveal orientational fluctuations that relax over a broad time scale. At short times, the relaxation dynamics exhibit hydrodynamic behavior. In contrast, the relaxation dynamics at long times are non-hydrodynamic, highly anisotropic, and increase in amplitude at small scattering angles. We argue that the slower dynamics arise from coupling between the director and the physically associated network, which prevents director orientational fluctuations from decaying …

Parametrization Dependence Of The Energy-Momentum Tensor And The Metric, Nej Bjerrum-Bohr, Jf Donoghue, Br Holstein

Barry R Holstein

We use results by Kirilin to comment that in general relativity the nonleading terms in the energy-momentum tensor of a particle depends on the parameterization of the gravitational field. The classical observables are parameterization independent after a change in coordinates. The quantum effects that emerge within the same calculation of the metric also depend on the parameterization and a full quantum calculation requires the inclusion of further diagrams. However, within a given parameterization the quantum effects calculated by us in a previous paper are well defined. Flaws of Kirilin’s proposed alternate metric definition are described and we explain why the …

Depleted Carbon Monoxide In Fragment C Of The Jupiter-Family Comet 73p/Schwassmann-Wachmann 3, M. A. Disanti, W. M. Anderson, G. L. Villanueva, B. P. Bonev, K. Magee-Sauer, E. L. Gibb, M. J. Mumma

Erika Gibb

The Shape Of Galaxy Cluster Dark Matter Haloes: Systematics Of Its Imprint On Cluster Gas And Comparison To Observations, Ricardo A. Flores, Brandon Allgood, Andrey V. Kravtsov, Joel R. Primack, David A. Buote, James S. Bullock

Ricardo Flores

Warm Hcn, C2h2, And Co In The Disk Of Gv Tau, Erika Gibb, K. A. Van Brunt, S. D. Brittain, T W. Rettig

Erika Gibb

Arrays Of Interacting Nanostructures: Ferromagnetic And Superconducting Cases, Andrei Ursache

Andrei E. Ursache

No abstract provided.

Simulation And Analysis Of Ultrafast Laser Pulse Induced Plasma Generation In Dielectric Materials, Jeremy Gulley, Sebastian Winkler, William Dennis

Jeremy R. Gulley

Recent experiments on optical damage by ultrashort laser pulses have demonstrated that the temporal pulseshape can dramatically influence plasma generation in fused silica and sapphire. In this work a modified 3+1D nonlinear Schroedinger equation for the pulse propagation coupled to a rate equation for the plasma density in the dielectric material is used to simulate pulse propagation and plasma formation in a range of dielectric materials. We use these simulations to analyze the influence of pulse-width, pulse-shape and beam geometry on the formation of the electron plasma and hence damage in the bulk material. In particular, when possible, we simulate …

The Abundance Of Carbon Dioxide Ice In The Quiescent Intracloud Medium, D. C. B. Whittet, S. S. Shenoy, E. A. Bergin, J. E. Chiar, P. A. Gerakines, E. L. Gibb, G. J. Melnick, D. A. Neufeld

Erika Gibb

Photon-Induced Conduction Modulation In Sio2 Thin Films Embedded With Ge Nanocrystals, L Ding, Tp Chen, M Yang, Ji Wong, Y Liu, Sf Yu, F.R. Zhu, Mc Tan, S Fung, Ch Tung, Ad Trigg

Professor ZHU, Fu Rong

No abstract provided.

Polyaniline On Crystalline Silicon Heterojunction Solar Cells, Weining Wang, E. A. Schiff

Weining Wang, Ph.D.

No abstract provided.

Self-Heating In Compost Piles Due To Biological Effects, Tim Marchant

Tim Marchant

The increase in temperature in compost piles/landfill sites due to micro-organisms undergoing exothermic reactions is modelled. A simplified model is considered in which only biological self-heating is present. The heat release rate due to biological activity is modelled by a function which is a monotonic increasing function of temperature over the range 0⩽T⩽a, whilst for T⩾a it is a monotone decreasing function of temperature. This functional dependence represents the fact that micro-organisms die or become dormant at high temperatures. The bifurcation behaviour is investigated for 1-d slab and 2-d rectangular slab geometries. In both cases there are two generic steady-state …

Solitary Wave Interaction For A Higher-Order Nonlinear Schrodinger Equation, Tim Marchant

Tim Marchant

Solitary wave interaction for a higher-order version of the nonlinear Schrödinger (NLS) equation is examined. An asymptotic transformation is used to transform a higher-order NLS equation to a higher-order member of the NLS integrable hierarchy, if an algebraic relationship between the higher-order coefficients is satisfied. The transformation is used to derive the higher-order one- and two-soliton solutions; in general, the N-soliton solution can be derived. It is shown that the higher-order collision is asymptotically elastic and analytical expressions are found for the higher-order phase and coordinate shifts. Numerical simulations of the interaction of two higher-order solitary waves are also performed. …

Optical Enhancement In Semitransparent Polymer Photovoltaic Cells, Gm Ng, El Kietzke, T Kietzke, Lw Tan, Pk Liew, F.R. Zhu

Professor ZHU, Fu Rong

No abstract provided.

Asymptotic Solitons On A Non-Zero Mean Level., Tim Marchant

Tim Marchant

The collision of solitary waves for a higher-order modified Korteweg-de Vries (mKdV) equation is examined. In particular, the collision between solitary waves with sech-type and algebraic (which only exist on a non-zero mean level) profiles is considered. An asymptotic transformation, valid if the higher-order coefficients satisfy a certain algebraic relationship, is used to transform the higher-order mKdV equation to an integrable member of the mKdV hierarchy. The transformation is used to show that the higher-order collision is asymptotically elastic and to derive the higher-order phase shifts. Numerical simulations of both elastic and inelastic collisions are performed. For the example covered …

Numerical Simulation Of Contaminant Flow In A Wool Scour Bowl., Tim Marchant

Tim Marchant

Wool scouring is the process of washing dirty wool after shearing. Our model numerically simulates contaminant movement in a wool scour bowl using the advection–dispersion equation. This is the first wool scour model to give time-dependent results and to model the transport of contaminants within a single scour bowl. Our aim is to gain a better understanding of the operating parameters that will produce efficient scouring. Investigating the effects of varying the parameters reveals simple, interesting relationships that give insight into the dynamics of a scour bowl.

Angular Dependent Magnetorestriction Study Of Cecoin5, Catalin Martin, Victor Correa, Kenneth Purcell, Timothy Timothy, Eric Palm, Stanley Tozer, George Schmiedeshoff, J Cooley

George Schmiedeshoff

Using a capacitive dilatometer designed to operate on the rotating stage of a top loading dilution refrigerator probe, we measured the magnetorestriction ( L(H)-L(0))/L(0), of the Heavy Fermion Superconductor CeCoIn5, along all three crystallographic direction, and with the magnetic field applied parallel both to the superconducting ab-planes and to the c-axis. When B||ab, the c-axis magnetorestriction features, besides a sharp jump at the upper critical field, a continuous, second-order like, transition at a lower field, which is consistent with previous observations from specific heat measurements. Our results are consistent with a field induced modulation of the superconducting order parameter (FFLO …

Imaging Voltage-Dependent Cell Motions With Heterodyne Mach-Zehnder Phase Microscopy, Christopher Fang-Yen, S Oh, Y Park, S Song, H S. Seung, M S. Feld

Christopher Fang-Yen

No abstract provided.

Tomographic Phase Microscopy, W Choi, Christopher Fang-Yen, K Badizadegan, S Oh, N Lue, R R. Dasari, M S. Feld

Christopher Fang-Yen

No abstract provided.

Significant Suppression Of Ferromagnetism By Hydrostatic Pressure In The Diluted Magnetic Semiconductor Sb2-Xvxte3 With X <~ 0.03, Jeffrey Dyck, T J. Mitchell, A J. Luciana, P C. Quayle, C DrašAr, P LošŤÁK

Jeffrey Dyck

The authors report on the hydrostatic pressure dependence of the magnetotransport properties of ferromagnetic Sb2-xVxTe3 single crystals with x=0.02—0.03. Pressure significantly increases the free hole concentration in these compounds. In turn, the Curie temperature is suppressed by roughly 40%, which goes against many models that would predict an increase in Curie temperature with increasing carrier concentration. These results indicate that the ferromagnetism in these materials is carrier mediated and that a full Ruderman-Kittel-Kasuya-Yosida model that takes into account the oscillatory nature of the indirect exchange interaction among localized spins is needed in order to explain the data.

Second Born Approximation And Coulomb Scattering, Br Holstein

Barry R Holstein

We examine the problem of calculating higher order contributions to the Coulomb scattering amplitude. To make contact with the well known result, it is necessary to modify the conventional definition of the scattering amplitude.

Modeling Innovation By A Kinetic Description Of The Patent Citation System, Gabor Csardi, Katherine J. Strandburg, Jan Tobochnik, Peter Erdi, Laszlo Zalanyi

Katherine J. Strandburg

This paper reports results of a network theory approach to the study of the United States patent system. We model the patent citation network as a discrete time, discrete space stochastic dynamic system. From patent data we extract an attractiveness function, A(k, l), which determines the likelihood that a patent will be cited. A(k, l) shows power law aging and perferential attachment, the exponent of the latter is increasing since 1993, suggesting that patent citations are increasingly concentrated on a relatively small number of patents. In particular, our results appear consistent with an increasing patent “thicket”, in which more and …

Digital Elevation Accuracy And Grid Cell Size: Effects On Computed Topographic Attributes, Rob H. Erskine, Timothy R. Green

Timothy R. Green

Terrain attributes are commonly used to explain the spatial variability of agronomic, pedologic, and hydrologic variables. The terrain attributes studied here (elevation, slope, aspect, and curvature) are estimated readily from digital elevation models (DEMs), but questions remain about how the accuracy and sample spacing of the elevation data affect the estimated attributes. The main objective of this study was to quantify differences in each terrain attribute due to factors affecting DEM accuracy and grid cell size. Three data sources were compared: (i) real-time kinematic global positioning system (RTKGPS); (ii) satellite-differentially corrected global positioning system (DGPS); and (iii) U.S. Geological Survey …