74,162 research outputs found

    Static and Dynamic Properties of Type-II Composite Fermion Wigner Crystals

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    The Wigner crystal of composite fermions is a strongly correlated state of complex emergent particles, and therefore its unambiguous detection would be of significant importance. Recent observation of optical resonances in the vicinity of filling factor {\nu} = 1/3 has been interpreted as evidence for a pinned Wigner crystal of composite fermions [Zhu et al., Phys. Rev. Lett. 105, 126803 (2010)]. We evaluate in a microscopic theory the shear modulus and the magnetophonon and magnetoplasmon dispersions of the composite fermion Wigner crystal in the vicinity of filling factors 1/3, 2/5, and 3/7. We determine the region of stability of the crystal phase, and also relate the frequency of its pinning mode to that of the corresponding electron crystal near integer fillings. These results are in good semiquantitative agreement with experiment, and therefore support the identification of the optical resonance as the pinning mode of the composite fermions Wigner crystal. Our calculations also bring out certain puzzling features, such as a relatively small melting temperature for the composite fermion Wigner crystal, and also suggest a higher asymmetry between Wigner crystals of composite fermion particles and holes than that observed experimentally.Comment: Composite Fermion Wigner Crystal; 14 pages, 9 figure

    Celescope catalog of ultraviolet stellar observations

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    The catalog contains the observational results obtained by the Celescope Experiment during the first 16 months of operation of NASA's Orbiting Astronomical Observatory (OAO-2). It lists the results of the stellar observations, along with selected ground-based information obtained from the available literature. Lunar observations (Ahmad and Deutschman, 1972), as well as other analyses of the data, are being published as separate papers. These data are available in two forms: (1) magnetic tapes and the necessary utility programs for reading and printing the contents of the tapes; and (2) this catalog, transcribed from the magnetic-tape catalog. The magnetic tape version contains not only the compiled results but also the results of the individual observations from which these averaged data were compiled

    Advanced Computer Dormant Reliability Study Final Report

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    Reliability of integrated circuits and discrete components of electronics for computer and dormant module for Minuteman

    Simulations of thermal Bose fields in the classical limit

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    We demonstrate that the time-dependent projected Gross-Pitaevskii equation derived earlier [Davis, et al., J. Phys. B 34, 4487 (2001)] can represent the highly occupied modes of a homogeneous, partially-condensed Bose gas. We find that this equation will evolve randomised initial wave functions to equilibrium, and compare our numerical data to the predictions of a gapless, second-order theory of Bose-Einstein condensation [S. A. Morgan, J. Phys. B 33, 3847 (2000)]. We find that we can determine the temperature of the equilibrium state when this theory is valid. Outside the range of perturbation theory we describe how to measure the temperature of our simulations. We also determine the dependence of the condensate fraction and specific heat on temperature for several interaction strengths, and observe the appearance of vortex networks. As the Gross-Pitaevskii equation is non-perturbative, we expect that it can describe the correct thermal behaviour of a Bose gas as long as all relevant modes are highly occupied.Comment: 15 pages, 12 figures, revtex4, follow up to Phys. Rev. Lett. 87 160402 (2001). v2: Modified after referee comments. Extra data added to two figures, section on temperature determination expande

    Non-universal dependence of spatiotemporal regularity on randomness in coupling connections

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    We investigate the spatiotemporal dynamics of a network of coupled nonlinear oscillators, modeled by sine circle maps, with varying degrees of randomness in coupling connections. We show that the change in the basin of attraction of the spatiotemporal fixed point due to varying fraction of random links pp, is crucially related to the nature of the local dynamics. Even the qualitative dependence of spatiotemporal regularity on pp changes drastically as the angular frequency of the oscillators change, ranging from monotonic increase or monotonic decrease, to non-monotonic variation. Thus it is evident here that the influence of random coupling connections on spatiotemporal order is highly non-universal, and depends very strongly on the nodal dynamics.Comment: 9 pages, 4 figure

    Celescope catalog of ultraviolet stellar observations. Magnetic tape version

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    Observational results obtained by the celescope experiment during the first 16 months of operation of NASA's Orbiting Astronomical Observatory are presented. Results of the stellar observations are listed along with selected ground-based information obtained from the available literature

    Celescope catalog of ultraviolet stellar observations: 5068 objects measured by Orbiting Astronomical Observatory (OAO-2)

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    During the 16 months that the Celescope Experiment operated, it took 8000 frames of data. This report describes the experiment, the data it gathered, the format of the magnetic tape containing the data, and a number of programs that were written to read and manipulate the tape. The tape version of the catalog contains Data on 5068 stars and is available from the National Space Sciences Data Center

    High Redshift Standard Candles: Predicted Cosmological Constraints

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    We investigate whether future measurements of high redshift standard candles (HzSCs) will be a powerful probe of dark energy, when compared to other types of planned dark energy measurements. Active galactic nuclei and gamma ray bursts have both been proposed as potential HzSC candidates. Due to their high luminosity, they can be used to probe unexplored regions in the expansion history of the universe. Information from these regions can help constrain the properties of dark energy, and in particular, whether it varies over time. We consider both linear and piecewise parameterizations of the dark energy equation of state, w(z)w(z), and assess the optimal redshift distribution a high-redshift standard-candle survey could take to constrain these models. The more general the form of the dark energy equation of state w(z)w(z) being tested, the more useful high-redshift standard candles become. For a linear parameterization of w(z)w(z), HzSCs give only small improvements over planned supernova and baryon acoustic oscillation measurements; a wide redshift range with many low redshift points is optimal to constrain this linear model. However to constrain a general, and thus potentially more informative, form of w(z)w(z), having many HzSCs can significantly improve limits on the nature of dark energy.Comment: Accepted MNRAS, 27 Pages, 15 figures, matches published versio
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