32,132 research outputs found

    Apparatus for changing the orientation and velocity of a spinning body traversing a path Patent

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    Development of method and apparatus for spinning satellite about selected axis after reaching predetermined orientatio

    Simulations of Evolving or Outbursting Molecular Protostellar Jets

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    The kinematic and radiative power of molecular jets is expected to change as a protostar undergoes permanent or episodal changes in the rate at which it accretes. We study here the consequences of evolving jet power on the spatial and velocity structure, as well as the fluxes, of molecular emission from the bipolar outflow. We consider a jet of rapidly increasing density and a jet in which the mass input is abruptly cut off. We perform three dimensional hydrodynamic simulations with atomic and molecular cooling and chemistry. In this work, highly collimated and sheared jets are assumed. We find that position-velocity diagrams, velocity-channel maps and the relative H2_2 and CO fluxes are potentially the best indicators of the evolutionary stage. In particular, the velocity width of the CO lines may prove most reliable although the often-quoted mass-velocity power-law index is probably not. We demonstrate how the relative H2_2 1--0 S(1) and CO J=1--0 fluxes evolve and apply this to interpret the phase of several outflows.Comment: 13 pages, 15 figures, Accepted for publication in MNRA

    Variations in atmospheric angular momentum

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    Twice-daily values of the atmosphere's angular momentum about the polar axis during the five years from 1976 through 1980 are presented in graphs and a table. The compilation is based on a global data set, incorporating 90 percent of the mass of the atmosphere. The relationship between changes in the angular momentum of the atmosphere and changes in the length of day is described, as are the main sources of error in the data. The variability in angular momentum is revealed in a preliminary fashion by means of a spectral decomposition. The data presented should stimulate comparisons with other measures of the length of day and so provide a basis for greater understanding of Earth-atmosphere interactions

    New York - New Jersey job expansion to moderate in 2001

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    New York City will set the pace for job growth in the New York-New Jersey region in 2001, with employment advancing 1.9 percent over the year. For the region as a whole, the rate of job growth will drop to 1.5 percent, from 2.2 percent in 2000.Employment - New York (State) ; Employment - New Jersey ; Federal Reserve District, 2nd

    RESOURCE QUALITY, AGRICULTURAL PRODUCTIVITY, AND FOOD SECURITY

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    USDA's Economic Research Service estimates that about 33 percent of the developing world's people suffer from insufficient food intake. Growth in agricultural productivity is critical to improvements in food security. We will examine the impact of changes in acreage and fertilizer response on production in 67 study countries and review the implications for food security.Food Consumption/Nutrition/Food Safety, Productivity Analysis,

    New York - New Jersey job recovery expected to continue in 1998

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    The pattern of employment recovery in the New York-New Jersey region is expected to remain unbroken in 1998, despite a slight slowing of job growth.Employment - New York (State) ; Employment - New Jersey ; Federal Reserve District, 2nd

    Non-linear behavior of fiber composite laminates

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    The non-linear behavior of fiber composite laminates which results from lamina non-linear characteristics was examined. The analysis uses a Ramberg-Osgood representation of the lamina transverse and shear stress strain curves in conjunction with deformation theory to describe the resultant laminate non-linear behavior. A laminate having an arbitrary number of oriented layers and subjected to a general state of membrane stress was treated. Parametric results and comparison with experimental data and prior theoretical results are presented

    A survey of stellar X-ray flares from the XMM-Newton serendipitous source catalogue: Hipparcos-Tycho cool stars

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    The X-ray emission from flares on cool (i.e. spectral-type F-M) stars is indicative of very energetic, transient phenomena, associated with energy release via magnetic reconnection. We present a uniform, large-scale survey of X-ray flare emission. The XMM-Newton Serendipitous Source Catalogue and its associated data products provide an excellent basis for a comprehensive and sensitive survey of stellar flares - both from targeted active stars and from those observed serendipitously in the half-degree diameter field-of-view of each observation. The 2XMM Catalogue and the associated time-series (`light-curve') data products have been used as the basis for a survey of X-ray flares from cool stars in the Hipparcos Tycho-2 catalogue. In addition, we have generated and analysed spectrally-resolved (i.e. hardness-ratio), X-ray light-curves. Where available, we have compared XMM OM UV/optical data with the X-ray light-curves. Our sample contains ~130 flares with well-observed profiles; they originate from ~70 stars. The flares range in duration from ~1e3 to ~1e4 s, have peak X-ray fluxes from ~1e-13 to ~1e-11 erg/cm2/s, peak X-ray luminosities from ~1e29 to ~1e32 erg/s, and X-ray energy output from ~1e32 to ~1e35 erg. Most of the ~30 serendipitously-observed stars have little previously reported information. The hardness-ratio plots clearly illustrate the spectral (and hence inferred temperature) variations characteristic of many flares, and provide an easily accessible overview of the data. We present flare frequency distributions from both target and serendipitous observations. The latter provide an unbiased (with respect to stellar activity) study of flare energetics; in addition, they allow us to predict numbers of stellar flares that may be detected in future X-ray wide-field surveys. The serendipitous sample demonstrates the need for care when calculating flaring rates.Comment: 26 pages, 24 figures. Additional tables and figures available as 4 ancillary files. To be published in Astronomy and Astrophysic

    Impact of satellite data on large-scale circulation statistics as determined from GLAS analyses during FGGE-SOP-1

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    A study using the analyses produced from the assimilation cycle of parallel model runs that both include and withhold satellite data was undertaken. The analyzed state of the atmosphere is performed using data from a certain test period during the first Special Observing Period (SOP) of the Global Weather Experiment (FGGE)

    The New York - New Jersey job recovery

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    Modest employment is expected to continue through 1997, with the New York City metropolitan area creating the bulk of new jobs.Federal Reserve District, 2nd ; Employment (Economic theory)
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