34,952 research outputs found

    Stellar Motions in the Polar Ring Galaxy NGC 4650A

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    We present the first measurement of the stellar kinematics in the polar ring of NGC 4650A. There is well defined rotation, with the stars and gas rotating in the same direction, and with similar amplitude. The gaseous and stellar kinematics suggest an approximately flat rotation curve, providing further support for the hypothesis that the polar material resides in a disk rather than in a ring. The kinematics of the emission line gas at and near the center of the S0 suggests that the polar disk lacks a central hole. We have not detected evidence for two, equal mass, counterrotating stellar polar streams, as is predicted in the resonance levitation model proposed by Tremaine & Yu. A merger seems the most likely explanation for the structure and kinematics of NGC 4650A.Comment: 4 pages, accepted for publication in ApJ Letter

    Improved analytic longitudinal response analysis for axisymmetric launch vehicles. Volume I - Linear analytic model

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    Improved analytic longitudinal response analysis for axisymmetric launch vehicles - linear mode

    A process-oriented language for describing aspects of reading comprehension

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    Includes bibliographical references (p. 36-38)The research described herein was supported in part by the National Institute of Education under Contract No. MS-NIE-C-400-76-011

    Control of bone remodelling by applied dynamic loads

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    The data showing the relationship between bone mass and peak strain magnitude prepared and submitted for publication. The data from experiments relating remodelling activity with static or dynamic loads were prepared and submitted for publication. Development of programs to relate the location of remodelling activity with he natural and artificial dynamic strain distributions continued. Experiments on the effect of different strain rates on the remodelling response continued

    Static versus dynamic loads as an influence on bone remodelling

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    Bone remodelling activity in the avian ulna was assessed under conditions of disuse alone, disuse with a superimposed continuous compressive load, and disuse interrupted by a short daily period of intermittent loading. The ulna preparation is made by two submetaphyseal osteotomies, the cut ends of the bone being covered with stainless steel caps which, together with the bone they enclosed, are pierced by pins emerging transcutaneously on the dorsal and ventral surfaces of the wing. The 110 mm long undisturbed section of the bone shaft can be protected from functional loading, loaded continuously in compression by joining the pins with springs, or loaded intermittently in compression by engaging the pins in an Instron machine. Similar loads (525 n) were used in both static and dynamic cases engendering similar peak strains at the bone's midshaft (-2000 x 10-6). The intermitent load was applied at a frequency of 1 Hz during a single 100 second period per day as a ramped square wave, with a rate of change of strain during the ramp of 0.01 per second

    Identifying the Burdens and Opportunities for Tribes and Communities in Federal Facility Cleanup Activities: Environmental Remediation Technology Assessment Matrix For Tribal and Community Decision-Makers

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    The cleanup of this country's federal facilities can affect a wide range of tribal and community interests and concerns. The technologies now in use, or being proposed by the Department of Energy, Department of Defense and other federal agencies can affect tribal treaty protected fishing, hunting and other rights, affect air and water quality thereby requiring the tribe to bear the burden of increased environmental regulation. The International Institute for Indigenous Resource Management developed a tribal and community decision-maker's Environmental Remediation Technology Assessment Matrix that will permit tribes and communities to array technical information about environmental remediation technologies against a backdrop of tribal and community environmental, health and safety, cultural, religious, treaty and other concerns and interests. Ultimately, the matrix will allow tribes and communities to assess the impact of proposed technologies on the wide range of tribal and community interests and will promote more informed participation in federal facility cleanup activities

    Stationary Points of Scalar Fields Coupled to Gravity

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    We investigate the dynamics of gravity coupled to a scalar field using a non-canonical form of the kinetic term. It is shown that its singular point represents an attractor for classical solutions and the stationary value of the field may occur distant from the minimum of the potential. In this paper properties of universes with such stationary states are considered. We reveal that such state can be responsible for modern dark energy density.Comment: H. Kroger, invited talk, FFP6, Udine (2004), revised version with corrected author lis
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