Physics Commons^™

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

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

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 …