88,056 research outputs found

    External validity in experimental methods: a social reality check

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    Fingers of God

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    Very long wavelength universal gravitational waves cannot now produce in clusters of galaxies velocity dispersions greater than that which these systems would possess if they were expanding with the Universe, if the Universe is not younger than 101010^{10} yr and Hubble's constant is not less than 50 km/sec/ Mpc. A diagram shows that actual velocity dispersions are significantly greater than this limit.Comment: Published long before the advent of large-scale redshift surveys, as "A Critique of Rees's Theory of Primordial Gravitational Radiation", this paper includes the first presentation of what has come to be known as the fingers-of-god effect. The effect is mentioned several hundred times in arXive papers, rarely with a wrong attribution, usually with none at al

    Some case studies of ocean wave physical processes utilizing the GSFC airborne radar ocean wave spectrometer

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    The NASA K sub u band Radar Ocean Wave Spectrometer (ROWS) is an experimental prototype of a possible future satellite instrument for low data rate global waves measurements. The ROWS technique, which utilizes short pulse radar altimeters in a conical scan mode near vertical incidence to map the directional slope spectrum in wave number and azimuth, is briefly described. The potential of the technique is illustrated by some specific case studies of wave physical processes utilizing the aircraft ROWS data. These include: (1) an evaluation of numerical hindcast model performance in storm sea conditions, (2) a study of fetch limited wave growth, and (3) a study of the fully developed sea state. Results of these studies, which are briefly summarized, show how directional wave spectral observations from a mobile platform can contribute enormously to our understanding of wave physical processes

    Overlay board for control consoles

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    Board that fits over the control panel decreases errors and time loss. Device has cutouts for controls and indicators, bears all appropriate labeling information, can be removed with the changing computer assignments, and guards against accidental changes in control settings

    Thermal analyses of the International Ultraviolet Explorer (IUE) scientific instrument using the NASTRAN thermal analyzer (NTA): A general purpose summary

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    The NTA Level 15.5.2/3, was used to provide non-linear steady-state (NLSS) and non-linear transient (NLTR) thermal predictions for the International Ultraviolet Explorer (IUE) Scientific Instrument (SI). NASTRAN structural models were used as the basis for the thermal models, which were produced by a straight forward conversion procedure. The accuracy of this technique was sub-sequently demonstrated by a comparison of NTA predicts with the results of a thermal vacuum test of the IUE Engineering Test Unit (ETU). Completion of these tasks was aided by the use of NTA subroutines
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