Physical Sciences and Mathematics Commons^™

Molecular Dynamics Simulation Of Sodium Dodecyl Sulfate Micelle In Water: Micellar Structural Characteristics And Counterion Distribution, Chrystal Bruce, Max Berkowitz, Lalith Perera, Malcolm Forbes

Chrystal D. Bruce

An all-atom 5 nanosecond molecular dynamics simulation of a water-solvated micelle containing 60 sodium dodecyl sulfate monomers was performed. Structural properties such as the radius of gyration, eccentricity, micellar size, accessible surface area, dihedral angle distribution, carbon atom distribution, and the orientation of the monomers toward the micelle center of mass were evaluated. The results indicate a stable micellar system over the duration of the simulation. Evaluation of the structure and motion of the sodium counterions show (1) a long equilibration time (1 nanosecond) is required to achieve a stable distribution of counterions and (2) approximately 25% of the sodium …

Transport Properties Of Polycrystalline Type-I Sn Clathrates, G. S. Nolas, J. L. Cohn, Jeffrey Dyck, C. Uher, J. Lang

Jeffrey Dyck

Thermal conductivity, resistivity, Seebeck coefficient, and Hall measurements on polycrystalline Sn-clathrate compounds with the type-I hydrate crystal structure are reported. Interstitial alkali-metal atoms in these compounds reside inside polyhedral cavities formed by the tetrahedrally bonded Sn network atoms. Localized disorder associated with “rattling” motion of these interstitial atoms contributes to the low thermal conductivity of these semiconducting compounds. The Hall coefficient and resistivity for some compounds exhibit nonmonotonic temperature dependences consistent with a crossover with decreasing temperature from conduction-band to impurity-band conduction. The carrier mobility is found to be low even in the absence of interstitial atoms within the Sn …

Three-Dimensional Dye Distribution In Photo-Oriented Liquid-Crystal Alignment Layers, S. Bardon, D. Coleman, N. A. Clark, T. Kosa, H. Yuan, Peter Palffy-Muhoray

Peter Palffy-Muhoray

The three-dimensional optical anisotropy of photo-buffed dye-doped polymer films and the resulting orientation imparted to a liquid crystal in contact are probed using total internal reflection. Although the linearly polarized writing light generates a uniaxial distribution of dye molecules, the polymer films are biaxial, a result of symmetry breaking by the film surface.

Smaller Solutions For The Firing Squad, Amber Settle, Janos Simon

Amber Settle

Profile Shapes For Optically Thick X-Ray Emission Lines From Stellar Winds., R. Ignace, K. G. Gayley

Richard Ignace

We consider the consequences of appreciable line optical depth for the profile shape of X-ray emission lines formed in stellar winds. The hot gas is thought to arise in distributed wind shocks, and the line formation is predominantly via collisional excitation followed by radiative decay. Such lines are often modelled as optically thin, but the theory has difficulty matching resolved X-ray line profiles. We suggest that for strong lines of abundant metals, newly created photons may undergo resonance scattering, modifying the emergent profile. Using Sobolev theory in a spherically symmetric wind, we show that thick-line resonance scattering leads to emission …

Thermoelectric Properties Of The N-Type Filled Skutterudite Ba0.3co4sb12 Doped With Ni, Jeffrey Dyck, Wei Chen, Ctirad Uher, Lidong Chen, Xinfeng Tang, Toshio Hirai

Jeffrey Dyck

Synthesis and electrical and thermal transport properties are reported for several filled skutterudite compounds doped with Ni: Ba0.3NixCo4_xSb12 with 0

Diluted Magnetic Semiconductors Based On Sb2àXvxte3 „0.01ïXï0.03., Jeffrey Dyck, Pavel Hájek, Petr LošŤÁK, Ctirad Uher

Jeffrey Dyck

We report on a diluted magnetic semiconductor based on the [formula] tetradymite structure doped with very low concentrations of vanadium (1—3 at. %). The anomalous transport behavior and robust magnetic hysteresis loops observed in magnetotransport and magnetic measurements are experimental manifestations of the ferromagnetic state in these materials. The [formula] exchange between holes and vanadium [formula] spins is estimated from the behavior of the magnetoresistance. A Curie temperature of at least 22 K is observed for [formula] This discovery offers possibilities for exploring magnetic properties of other tetradymite structure semiconductors doped with a wide range of [formula] transition metals.

Effect Of Ni On The Transport And Magnetic Properties Of Co1àXnixsb3, Jeffrey Dyck, Wei Chen, Jihui Yang, Gregory P. Meisner, Ctirad Uher

Jeffrey Dyck

The filled skutterudite compounds based on the binary skutterudite [formula] are currently being investigated for their potential applications as thermoelectric materials. One route to optimization of these compounds is by doping on the Co site. An obvious candidate for an n-type dopant is Ni, since it has one more electron in its valence shell than Co. Up to now, however, only high concentrations of Ni in [formula] have been studied; and the valence of Ni in this compound and its influence on the transport and magnetic properties has been an open question. We present electrical resistivity, thermopower, Hall effect, magnetoresistance, …

Who's Minding The Kids? Pollution, Public Schools, And Environmental Justice In Los Angeles, Manuel Pastor, James Sadd, Rachel Morello-Frosch

James Sadd

Although previous environmental justice research has focused on analysis of the disproportionate burden of environmental hazards on minority residents, few studies have examined demographic inequities in health risks among children. This article evaluates the demographic distribution of potentially hazardous facilities and health risks associated with ambient air toxics exposures among public schoolchildren in the Los Angeles Unified School District. Methods. We combine Geographic Information System analysis with multivariate statistics to compare enrollment and demographic information for students who attend district schools with the spatial pattern of land use, locations of toxic emissions and facilities, and calculated indices of estimated lifetime …

Mysql & Php For Data Librarians Workshop, Christopher Hoebeke, Patrick Yott

Christopher H Hoebeke

No abstract provided.

Parallel Implementation Of The Bi-Cgstab Method With Block Red–Black Gauss–Seidel Preconditioner Applied To The Hermite Collocation Discretization Of Partial Differential Equations, Stephen Brill, George Pinder

Stephen H. Brill

We describe herein the parallel implementation of the Bi-CGSTAB method with a block red–black Gauss–Seidel (RBGS) preconditioner applied to the systems of linear algebraic equations that arise from the Hermite collocation discretization of partial differential equations in two spatial dimensions. The method is implemented on the Cray T3E, a parallel processing supercomputer. Speedup results are discussed.

Low-Temperature Ferromagnetism And Magnetic Anisotropy In The Novel Diluted Magnetic Semiconductor Sb2−Xvxte3, Jeffrey Dyck, Wei Chen, Pavel Hájek, Petr Lošt’Ák, Ctirad Uher

Jeffrey Dyck

We report on a novel diluted magnetic semiconductor based on the Sb2Te3 tetradymite structure doped with very low concentrations of vanadium (1–3at%). Anisotropy in the magnetic hysteresis loops and magnetoresistance are observed at temperatures below the ferromagnetic ordering temperature. A Curie temperature of 24K is observed for Sb1.97V0.03Te3.

Quantum Corrections To The Reissner-Nordstrom And Kerr-Newman Metrics, Jf Donoghue, Br Holstein, B Garbrecht, T Konstandin

Barry R Holstein

We use effective field theory techniques to examine the quantum corrections to the gravitational metrics of charged particles, with and without spin. In momentum space the masslessness of the photon implies the presence of non-analytic pieces ~-q2, q2log(-q2), etc. in the form factors of the energy-momentum tensor. We show how the former reproduces the classical non-linear terms of the Reissner-Nordstrom and Kerr-Newman metrics while the latter can be interpreted as quantum corrections to these metrics, of order G&unknown;/mr3.

Influence Of Electron-Phonon Interaction On The Lattice Thermal Conductivity Of Co1àXnixsb3, J. Yang, D. T. Morelli, G. P. Meisner, W. Chen, Jeffrey Dyck, C. Uher

Jeffrey Dyck

We have investigated the effect of electron-phonon scattering in a series of n-type nickel-doped [formula] skutterudite materials. Samples were polycrystalline of the form [formula] with [formula] 0.001, 0.003, 0.005, 0.0075, and 0.01. The lattice thermal conductivity decreases dramatically with increasing Ni doping for [formula] For higher Ni concentration the reduction of the lattice thermal conductivity saturates. Our theoretical analysis indicates that this reduction of the lattice thermal conductivity cannot be explained solely by point-defect scattering of the phonons. Rather, we can fit the lattice thermal conductivity of Ni-doped [formula] by introducing an electron-phonon scattering mechanism, and this demonstrates that the …

On The Feasibility Of Geopressure Detection From Seismic Data In Saudi Arabia., Thomas M. Loretto, James J. Funk

Thomas M Loretto

No abstract provided.

Enthalpies Of Sublimation Of Organic And Organometallic Compounds. 1910–2001, James S. Chickos, William E. Acree

James Chickos

No abstract provided.

Transparent Fault Tolerance For Web Services Based Architectures, Vijay Dialani, Simon Miles, Luc Moreau, David De Roure, Michael Luck

Vijay Dialani

Service-based architectures enable the development of new classes of Grid and distributed applications. One of the main capabilities provided by such systems is the dynamic and flexible integration of services, according to which services are allowed to be a part of more than one distributed system and simultaneously serve different applications. This increased flexibility in system composition makes it difficult to address classical distributed system issues such as fault-tolerance. While it is relatively easy to make an individual service fault-tolerant, improving fault-tolerance of services collaborating in multiple application scenarios is a challenging task. In this paper, we look at the …

Cretaceous−Cenozoic History Of The Southern Tan-Lu Fault Zone: Apatite Fission-Track And Structural Constraints From The Dabie Shan (Eastern China), J Grimmer, R Jonckheere, E Enkelmann, L Ratschbacher, B Hacker, Ann Blythe, G Wagner, Q Wue, S Liu, S Dong

Ann Blythe

Apatite fission-track (AFT) and structural data outline the Late Cretaceous−Cenozoic history of the southern Tan-Lu fault zone (TLFZ), one of Asia's major faults, the Triassic–Jurassic Dabie orogen, Earth's largest track of ultrahigh-pressure rock exposure, and its foreland, the Yangtze foreland fold-thrust belt. The fission-track analyses utilized the independent (φ-), Z- and ξ-methods for age determination, which yielded within error identical ages. Ages from Triassic–Jurassic syn-orogenic foreland sediments are younger than their depositional age and thus were reset. A group of ages records rapid cooling following shallow emplacement of granitoids of the widespread latest Jurassic−Early Cretaceous “Yanshanian” magmatism. Most ages are …

Controls On The Erosion And Geomorphic Evolution Of The San Bernardino And San Gabriel Mountains, Southern California, J Spotila, M House, Ann Blythe, N Niemi, G Bank

Ann Blythe

No abstract provided.

Statistical Analysis Of Reliability, Maintainability And Supportability Data, Caroline Lubert

Caroline P Lubert

No abstract provided.

Committee On Climate Change And Sustainable Development: 2001 Annual Report, John Dernbach

John C. Dernbach

No abstract provided.

Deformation Associated With A Continental Normal Fault System, Western Grand Canyon, Arizona, Phillip Resor, David Pollard

Phillip G Resor

In the western Grand Canyon, the Colorado River cuts through a series of moderate offset normal faults that mark the transition between the Colorado Plateau and the Basin and Range tectonic provinces. Both hanging wall and footwall rocks are exposed over > 1,000 m of vertical section, and contain relatively simple pre-existing structures. The area thus presents an opportunity to investigate processes of continental extension without cross-cutting fault patterns and large rotations typical of much of the Basin and Range. We have mapped 8 km of the Froggy Fault, including ~ 600 m of vertical section, and deformed strata of the …

Stable Refinable Generators Of Shift Invariant Spaces With Certain Regularities And Vanishing Moments, Tian-Xiao He

Tian-Xiao He

In this paper, we discuss the stable refinable functions that generate shift in variant (SI) spaces and possess the largest possible regularities and required vanishing moments. The stability of the corresponding complementary spaces is also discussed.

Synchronization Of The Human Cortical Working Memory Network, Sharlene Newman, Marcel Just, Patricia Carpenter

Marcel Adam Just

No abstract provided.

High-Order Interaction Of Solitary Waves On Shallow Water, Prof. Tim Marchant

Tim Marchant

The interaction of solitary waves on shallow water is examined to fourth order. At first order the interaction is governed by the Korteweg-de Vries (KdV) equation, and it is shown that the unidirectional assumption, of right-moving waves only, is incompatible with mass conservation at third order. To resolve this, a mass conserving system of KdV equations, involving both right- and left-moving waves, is derived to third order. A fourth-order interaction term, in which the right- and left-moving waves are coupled, is also derived as this term is crucial in determining the fourth-order change in solitary wave amplitude. The form of …

Handbook On Fence Viewers And Laws On Fences In The Commonwealth Of Massachusetts, Joseph Larson

Joseph S. Larson

This handbook is intended to serve as an informal guide to the laws that pertain to Fence Viewers and fencing in general in the Commonwealth of Massachusetts. We have used two primary sources for the current Massachusetts laws. We first searched the unofficial on-line text of the Massachusetts General Laws provided on the Internet (http://www.state.ma.us/legis/laws/mgl/) by the State Senate. This was followed by an examination of the laws, court decisions and notes as they appear in the most recent volumes and annual supplements of Massachusetts General Laws Annotated (1977). In every instance, the text describing each law consists only of …

The Occurrence Of Limit-Cycles During Feedback Control Of Microwave Heating, Prof. Tim Marchant

Tim Marchant

The microwave heating of one- and two-dimensional slabs, subject to linear feedback control, is examined. A semianalytical model of the microwave heating is developed using the Galerkin method. A local stability analysis of the model indicates that Hopf bifurcations occur; the regions of parameter space in which limit-cycles exist are identified. An efficient numerical scheme for the solution of the governing equations, which consist of the forced heat equation and a Helmholtz equation describing the electric-field amplitude, is also developed. An excellent comparison between numerical solutions of the semianalytical model and the governing equations is obtained for the temporal evolution …

Cubic Autocatalytic Reaction-Diffusion Equations: Semi-Analytical Solutions, Prof. Tim Marchant

Tim Marchant

The Gray-Scott model of cubic-autocatalysis with linear decay is coupled with diffusion and considered in a one-dimensional reactor (a reaction-diffusion cell). The boundaries of the reactor are permeable, so diffusion occurs from external reservoirs that contain fixed concentrations of the reactant and catalyst. The Galerkin method is used to approximate the spatial structure of the reactant and autocatalyst concentrations in the reactor. Ordinary differential equations are then obtained as an approximation to the governing partial differential equations. The ordinary differential equations are then analysed to obtain semi-analytical results for the reaction-diffusion cell. Steady-state concentration profiles and bifurcation diagrams are obtained …

Semi-Analytical Solutions For Continuous-Flow Microwave Reactors, Prof. Tim Marchant

Tim Marchant

A prototype chemical reaction is examined in both one and two-dimensional continuous-flow microwave reactors, which are unstirred so the effects of diffusion are important. The reaction rate obeys the Arrhenius law and the thermal absorptivity of the reactor contents is assumed to be both temperature- and concentration-dependent. The governing equations consist of coupled reaction-diffusion equations for the temperature and reactant concentration, plus a Helmholtz equation describing the electric-field amplitude in the reactor. The Galerkin method is used to develop a semi-analytical microwave reactor model, which consists of ordinary differential equations. A stability analysis is performed on the semi-analytical model. This …

The Initial Boundary Problem For The Korteweg-De Vries Equation On The Negative Quarter-Plane, Prof. Tim Marchant

Tim Marchant

The initial boundary-value problem for the Korteweg-de Vries (KdV) equation on the negative quarter-plane, x < 0 and t > 0, is considered. The formulation of this problem is different to the usual initial boundary-value problem on the positive quarter-plane, for which x > 0 and t > 0. Two boundary conditions are required at x = 0 for the negative quarter-plane problem, in contrast to the one boundary condition needed at x = 0 for the positive quarter-plane problem. Solutions of the KdV equation on the infinite line, such as the soliton, cnoidal wave, mean height variation and undular bore solution, are used to find approximate …