9,911 research outputs found

    Attitude control system for sounding rockets Patent

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    Development of attitude control system for sounding rocket stabilization during ballistic phase of fligh

    Utility operational experience on the NASA/DOE MOD-0A 200-kW wind turbine

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    The Mod-0A 200 wind turbine was designed and fabricated as part of the Federal Wind Energy Program. Early wind turbine operation and performance data were obtained while gaining initial experience in the operation of large, horizontal axis wind turbines in typical utility environments. The Mod-0A wind turbine was turned over to the Town of Clayton Light and Water Plant, Clayton, NM, for utility operation and on December 31, 1978, the machine had completed ten months of utility operation. The machine is described and the recent operational experience at Clayton, NMis documented

    Catholic and charismatic : a study in personality theory within Catholic congregations

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    This study set out to conceptualise and measure Charismatic orientation (openness to charismatic experience) and traditional Catholic orientation (Catholic identity) among a sample of 670 Catholic churchgoers in order to test whether attachment to Catholic Charismatic Renewal strengthened or weakened the sense of traditional Catholic identity among churchgoing Catholics. This research question was set within the broader consideration of the location of Charismatic orientation and Catholic orientation within Eysenck's three dimensional model of personality. The data revealed a strong positive association between Charismatic experience and Catholic identity. Higher scores on the index of Charismatic orientation were associated with higher extraversion scores, with higher neuroticism scores, and with higher levels of mass attendance and personal prayer. Higher scores on the index of Catholic orientation were associated with being female, being older, higher neuroticism scores, and higher levels of mass attendance and personal prayer

    Torsion and bending of nucleic acids studied by subnanosecond time-resolved fluorescence depolarization of intercalated dyes

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    Subnanosecond time‐resolved fluorescence depolarization has been used to monitor the reorientation of ethidium bromide intercalated in native DNA, synthetic polynucleotide complexes, and in supercoiled plasmid DNA. The fluorescence polarization anisotropy was successfully analyzed with an elastic model of DNA dynamics, including both torsion and bending, which yielded an accurate value for the torsional rigidity of the different DNA samples. The dependence of the torsional rigidity on the base sequence, helical structure, and tertiary structure was experimentally observed. The magnitude of the polyelectrolyte contribution to the torsional rigidity of DNA was measured over a wide range of ionic strength, and compared with polyelectrolyte theories for the persistence length. We also observed a rapid initial reorientation of the intercalated ethidium which had a much smaller amplitude in RNA than in DNA

    Time-resolved spectroscopy of macromolecules: Effect of helical structure on the torsional dynamics of DNA and RNA

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    The torsional rigidity of DNA and RNA is measured via the fluorescence depolarization technique

    Zero area singularities in general relativity and inverse mean curvature flow

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    First we restate the definition of a Zero Area Singularity, recently introduced by H. Bray. We then consider several definitions of mass for these singularities. We use the Inverse Mean Curvature Flow to prove some new results about the mass of a singularity, the ADM mass of the manifold, and the capacity of the singularity.Comment: 13 page

    Variational quantum Monte Carlo simulations with tensor-network states

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    We show that the formalism of tensor-network states, such as the matrix product states (MPS), can be used as a basis for variational quantum Monte Carlo simulations. Using a stochastic optimization method, we demonstrate the potential of this approach by explicit MPS calculations for the transverse Ising chain with up to N=256 spins at criticality, using periodic boundary conditions and D*D matrices with D up to 48. The computational cost of our scheme formally scales as ND^3, whereas standard MPS approaches and the related density matrix renromalization group method scale as ND^5 and ND^6, respectively, for periodic systems.Comment: 4+ pages, 2 figures. v2: improved data, comparisons with exact results, to appear in Phys Rev Let

    Geometric phases and anholonomy for a class of chaotic classical systems

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    Berry's phase may be viewed as arising from the parallel transport of a quantal state around a loop in parameter space. In this Letter, the classical limit of this transport is obtained for a particular class of chaotic systems. It is shown that this ``classical parallel transport'' is anholonomic --- transport around a closed curve in parameter space does not bring a point in phase space back to itself --- and is intimately related to the Robbins-Berry classical two-form.Comment: Revtex, 11 pages, no figures

    Effect of many-body interactions on the solid-liquid phase-behavior of charge-stabilized colloidal suspensions

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    The solid-liquid phase-diagram of charge-stabilized colloidal suspensions is calculated using a technique that combines a continuous Poisson-Boltzmann description for the microscopic electrolyte ions with a molecular-dynamics simulation for the macroionic colloidal spheres. While correlations between the microions are neglected in this approach, many-body interactions between the colloids are fully included. The solid-liquid transition is determined at a high colloid volume fraction where many-body interactions are expected to be strong. With a view to the Derjaguin-Landau-Verwey-Overbeek theory predicting that colloids interact via Yukawa pair-potentials, we compare our results with the phase diagram of a simple Yukawa liquid. Good agreement is found at high salt conditions, while at low ionic strength considerable deviations are observed. By calculating effective colloid-colloid pair-interactions it is demonstrated that these differences are due to many-body interactions. We suggest a density-dependent pair-potential in the form of a truncated Yukawa potential, and show that it offers a considerably improved description of the solid-liquid phase-behavior of concentrated colloidal suspensions

    Melting-freezing cycles in a relatively sheared pair of crystalline monolayers

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    The nonequilibrium dynamical behaviour that arises when two ordered two-dimensional monolayers of particles are sheared over each other is studied in Brownian dynamics simulations. A curious sequence of nonequilibrium states is observed as the driving rate is increased, the most striking of which is a sliding state with irregular alternation between disordered and ordered states. We comment on possible mechanisms underlying these cycles, and experiments that could observe them.Comment: 7 pages, 8 figures, minor changes in text and figures, references adde
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