34,507 research outputs found

    Publications of the exobiology program for 1984: A special bibliography

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    A bibliography of NASA exobiology programs is given. Planetary environments; chemical evolution; organic geochemistry; extraterrestrial intelligence; and the effect of planetary solar and astrophysical phenomena on the evolution of complex life in the universe are among the topics listed

    Observation of Single Transits in Supercooled Monatomic Liquids

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    A transit is the motion of a system from one many-particle potential energy valley to another. We report the observation of transits in molecular dynamics (MD) calculations of supercooled liquid argon and sodium. Each transit is a correlated simultaneous shift in the equilibrium positions of a small local group of particles, as revealed in the fluctuating graphs of the particle coordinates versus time. This is the first reported direct observation of transit motion in a monatomic liquid in thermal equilibrium. We found transits involving 2 to 11 particles, having mean shift in equilibrium position on the order of 0.4 R_1 in argon and 0.25 R_1 in sodium, where R_1 is the nearest neighbor distance. The time it takes for a transit to occur is approximately one mean vibrational period, confirming that transits are fast.Comment: 19 pages, 8 figure

    Conceptualizing Student Practice for the 21st Century: Educational and Ethical Considerations in Modernizing the District of Columbia Student Practice Rules

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    This article traces the history of the amendment process. It provides a short history of student practice rules and then, using the student practice rule in effect in the District of Columbia prior to the 2014 amendments, describes the various components of those rules that courts and bars across the nation have implemented to assist courts, advance legal education, and preserve advocates’ ethical obligations to clients. It then describes some of the comments to the proposed amendments offered by the District of Columbia Bar and other D.C. lawyers during the public comment period and the modifications to the District of Columbia student practice rule that the District of Columbia Court of Appeals accepted. Finally, it discusses some areas of disagreement that arose during the process and a description of the reasons for those disagreements

    Low-energy interaction of composite spin-half systems with scalar and vector fields

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    We consider a composite spin-half particle moving in spatially-varying scalar and vector fields. The vector field is assumed to couple to a conserved charge, but no assumption is made about either the structure of the composite or its coupling to the scalar field. A general form for the piece of the spin-orbit interaction of the composite with the scalar and vector fields which is first-order in momentum transfer Q{\bf Q} and second-order in the fields is derived.Comment: 10 pages, RevTe

    A covariant gauge-invariant three-dimensional description of relativistic bound-states

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    A formalism is presented which allows covariant three-dimensional bound-state equations to be derived systematically from four-dimensional ones without the use of delta-functions. The amplitude for the interaction of a bound state described by these equations with an electromagnetic probe is constructed. This amplitude is shown to be gauge invariant if the formalism is truncated at the same coupling-constant order in both the interaction kernel of the integral equation and the electromagnetic current operator.Comment: 17 pages, RevTeX, uses BoxedEPS.te

    A summary of the test procedures and operational details of an ocean dumping pollution monitoring experiment conducted 7 October 1976

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    A remote sensor experiment was conducted at a sewage sludge dump site off the Delaware/Maryland coast. Two aircraft serving as remote sensor platforms flew over the dump site during a sludge dump. One aircraft carried a multispectral scanner and the other aircraft carried a rapid scanning spectrometer. Data from sea-truth stations were collected concurrent with overpasses of the aircraft. All sensors were operational and produced good digital data

    Design for a space molecular sink simulator

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    Space molecular sink vacuum syste
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