2,294 research outputs found

    Environmental analysis of the chemical release module

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    The environmental analysis of the Chemical Release Module (a free flying spacecraft deployed from the space shuttle to perform chemical release experiments) is reviewed. Considerations of possible effects of the injectants on human health, ionosphere, weather, ground based optical astronomical observations, and satellite operations are included. It is concluded that no deleterious environmental effects of widespread or long lasting nature are anticipated from chemical releases in the upper atmosphere of the type indicated for the program

    Combating stem and leaf rust of wheat: Historical perspective, impacts, and lessons learned

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    millions fed, food security, wheat rust, stem rust, leaf rust, Norman Borlaug,

    Cost/benefit trade-offs for reducing the energy consumption of commercial air transportation (RECAT)

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    A study has been performed to evaluate the opportunities for reducing the energy requirements of the U.S. domestic air passenger transport system through improved operational techniques, modified in-service aircraft, derivatives of current production models, or new aircraft using either current or advanced technology. Each of the fuel-conserving alternatives has been investigated individually to test its potential for fuel conservation relative to a hypothetical baseline case in which current, in-production aircraft types are assumed to operate, without modification and with current operational techniques, into the future out to the year 2000

    A dilemma in representing observables in quantum mechanics

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    There are self-adjoint operators which determine both spectral and semispectral measures. These measures have very different commutativity and covariance properties. This fact poses a serious question on the physical meaning of such a self-adjoint operator and its associated operator measures.Comment: 10 page

    The Pegg-Barnett Formalism and Covariant Phase Observables

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    We compare the Pegg-Barnett (PB) formalism with the covariant phase observable approach to the problem of quantum phase and show that PB-formalism gives essentially the same results as the canonical (covariant) phase observable. We also show that PB-formalism can be extended to cover all covariant phase observables including the covariant phase observable arising from the angle margin of the Husimi Q-function.Comment: 10 page

    Collective modes and correlations in one-component plasmas

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    The static and time-dependent potential and surface charge correlations in a plasma with a boundary are computed for different shapes of the boundary. The case of a spheroidal or spherical one-component plasma is studied in detail because experimental results are available for such systems. Also, since there is some knowlegde both experimental and theoretical about the electrostatic collective modes of these plasmas, the time-dependent correlations are computed using a method involving these modes.Comment: 20 pages, plain TeX, submitted to Phys. Rev.

    Dynamic Phase Transitions in Cell Spreading

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    We monitored isotropic spreading of mouse embryonic fibroblasts on fibronectin-coated substrates. Cell adhesion area versus time was measured via total internal reflection fluorescence microscopy. Spreading proceeds in well-defined phases. We found a power-law area growth with distinct exponents a_i in three sequential phases, which we denote basal (a_1=0.4+-0.2), continous (a_2=1.6+-0.9) and contractile (a_3=0.3+-0.2) spreading. High resolution differential interference contrast microscopy was used to characterize local membrane dynamics at the spreading front. Fourier power spectra of membrane velocity reveal the sudden development of periodic membrane retractions at the transition from continous to contractile spreading. We propose that the classification of cell spreading into phases with distinct functional characteristics and protein activity patterns serves as a paradigm for a general program of a phase classification of cellular phenotype. Biological variability is drastically reduced when only the corresponding phases are used for comparison across species/different cell lines.Comment: 4 pages, 5 figure

    The possibility of Z(4430) resonance structure description in πψ\pi\psi' reaction

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    The possible description of Z(4430) as a pseudoresonance structure in πψ\pi \psi' reaction, is considered. The analysis is performed with single-scattering contribution to πψ\pi \psi' elastic scattering via DD1(2420)D^*D_1(2420) intermediate energy.Comment: 3 pages, 4 figure

    Some Day I\u27ll Make You Care

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    Illustration of woman\u27s face with roses and stemshttps://scholarsjunction.msstate.edu/cht-sheet-music/7613/thumbnail.jp

    Decoherence in Ion Trap Quantum Computers

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    The {\it intrinsic} decoherence from vibrational coupling of the ions in the Cirac-Zoller quantum computer [Phys. Rev. Lett. {\bf 74}, 4091 (1995)] is considered. Starting from a state in which the vibrational modes are at a temperature TT, and each ion is in a superposition of an excited and a ground state, an adiabatic approximation is used to find the inclusive probability P(t)P(t) for the ions to evolve as they would without the vibrations, and for the vibrational modes to evolve into any final state. An analytic form is found for P(t)P(t) at T=0T=0, and the decoherence time is found for all TT. The decoherence is found to be quite small, even for 1000 ions.Comment: 11 pages, no figures, uses revte
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