20,662 research outputs found

    A quasi-Lagrangian study of mid-ocean variability using long range SOFAR floats

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    Twenty neutrally buoyant SOFAR floats were used in the Mid-Ocean Dynamics Experiment (MODE) to study the structure and variability of the deep ocean currents. The floats were clustered so that the pattern of motions could be resolved (mapping and pattern recognition). A number of float trajectories are shown and the very individual character of their signature is emphasized. Some floats remain nearly stationary for a year whereas others will cover hundreds of kilometers to the south or west in just a few months...

    High spatial resolution observations of CUDSS14A: a SCUBA-selected ultraluminous galaxy at high redshift

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    The definitive version is available at www.blackwell-synergy.com '. Copyright Blackwell Publishing DOI : 10.1046/j.1365-8711.2000.03822.xWe present a high-resolutionmillimetre interferometric image of the brightest SCUBA- selected galaxy from the Canada-UK deep SCUBA survey (CUDSS). We make a very clear detection at 1.3 mm, but fail to resolve any structure in the source.Peer reviewe

    Relativistic effects in Ni II and the search for variation of the fine structure constant

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    Theories unifying gravity and other interactions suggest the possibility of spatial and temporal variation of physical ``constants'' in the Universe. Detection of high redshift absorption systems intersecting the sight lines towards distant quasars provide a powerful tool for measuring these variations. In the present paper we demonstrate that high sensitivity to variation of the fine structure constant alpha can be obtained by comparing cosmic and laboratory spectra of the Ni II ion. Relativistic effects in Ni II reveal many interesting features. The Ni II spectrum exhibits avoided level crossing phenomenon under variation of alpha and the intervals between the levels have strong nonlinear dependencies on relativistic corrections. The values of the transition frequency shifts, due to the change of alpha, vary significantly from state to state including change of the sign. This enhances the sensitivity to the variation of alpha and reduces possible systematic errors. The calculations of alpha-dependence of the nickel ion spectral lines that are detectable in quasar absorption spectra have been performed using a relativistic configuration interaction method.Comment: 13 pages, 1 figure, accepted by Phys. Rev. A, typos corrected, acknowledgment adde

    HI and OH absorption in the lensing galaxy of MG J0414+0534

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    We report the detection of \HI 21-cm absorption in the z=0.96z=0.96 early-type lensing galaxy towards MG J0414+0534 with the Green Bank Telescope. The absorption, with total NHI=1.6×1018(Ts/f)cm−2N_{\rm HI}=1.6 \times 10^{18} (T_{\rm s}/f) {\rm cm}^{-2}, is resolved into two strong components, probably due to the two strongest lens components, which are separated by 0.4\arcsec. Unlike the other three lenses which have been detected in \HI, J0414+0534 does not exhibit strong OH absorption, giving a OH/\HI column density ratio of N_{\rm OH}/N_{\rm HI}\lapp10^{-6} (for Ts=100T_{\rm s}=100 K, Tx=10T_{\rm x}=10 K and fHI=fOH=1f_{\rm HI}=f_{\rm OH}=1). This underabundance of molecular gas may indicate that the extreme optical--near-IR colour (V−K=10.26V-K=10.26) along the line-of-sight is not due to the lens. We therefore suggest that despite the strong upper limits on molecular absorption at the quasar redshift, as traced by millimetre lines, the extinction occurs primarily in the quasar host galaxy.Comment: Accepted by MNRAS Letters, 5 (and a bit) pages, 5 figure

    A study of the potential impacts of space utilization

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    Because the demand for comprehensive impact analysis of space technologies will increase with the use of space shuttles, the academic social sciences/humanities community was surveyed in order to determine their interests in space utilization, to develop a list of current and planned courses, and to generate a preliminary matrix of relevant social sciences. The academic scope/focus of a proposed social science space-related journal was identified including the disciplines which should be represented in the editorial board/reviewer system. The time and funding necessary to develop a self-sustaining journal were assessed. Cost income, general organizational structure, marking/distribution and funding sources were analyzed. Recommendations based on the survey are included

    High-resolution saturation spectroscopy of singly-ionized iron with a pulsed uv laser

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    We describe the design and realization of a scheme for uv laser spectroscopy of singly-ionized iron (Fe II) with very high resolution. A buffer-gas cooled laser ablation source is used to provide a plasma close to room temperature with a high density of Fe II. We combine this with a scheme for pulsed-laser saturation spectroscopy to yield sub-Doppler resolution. In a demonstration experiment, we have examined an Fe II transition near 260 nm, attaining a linewidth of about 250 MHz. The method is well-suited to measuring transition frequencies and hyperfine structure. It could also be used to measure small isotope shifts in isotope-enriched samples.Comment: 9 pages, 5 figures, updated Fig. 3. For submission to J. Phys.

    Bulk and shear relaxation in glasses and highly viscous liquids

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    The ratio between the couplings of a relaxational process to compression and shear, respectively, is calculated in the Eshelby picture of structural rearrangements within a surrounding elastic matrix, assuming a constant density of stable structures in distortion space. The result is compared to experimental data for the low-temperature tunneling states in glasses and to Prigogine-Defay data at the glass transition from the literature.Comment: 6 pages, 2 figures, 53 references; version after understanding the Prigogine-Defay ratio at the glass transition in the accompanying paper arXiv:1203.3555 [cond-mat.dis-nn

    Professionalism and the Millbank Tendency: The Political Sociology of New Labour's employees

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    This article analyses party employees, one of the most under-researched subjects in the study of British political parties. We draw on a blend of quantitative and qualitative data in order to shed light on the social and political profiles of Labour Party staff, and on the question of their professionalisation. The latter theme is developed through a model derived from the sociology of professions. While a relatively limited proportion of party employees conform to the pure ideal-type of professionalism, a considerably greater number manifest enough of the core characteristics of specialisation, commitment, mobility, autonomy and self-regulation to be reasonably described as 'professionals in pursuit of political outcomes'

    Optical variability of the accretion disk around the intermediate mass black hole ESO 243-49 HLX-1 during the 2012 outburst

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    We present dedicated quasi-simultaneous X-ray (Swift) and optical (Very Large Telescope (VLT), V- and R-band) observations of the intermediate mass black hole candidate ESO 243-49 HLX-1 before and during the 2012 outburst. We show that the V-band magnitudes vary with time, thus proving that a portion of the observed emission originates in the accretion disk. Using the first quiescent optical observations of HLX-1, we show that the stellar population surrounding HLX-1 is fainter than V~25.1 and R~24.2. We show that the optical emission may increase before the X-ray emission consistent with the scenario proposed by Lasota et al. (2011) in which the regular outbursts could be related to the passage at periastron of a star circling the intermediate mass black hole in an eccentric orbit, which triggers mass transfer into a quasi-permanent accretion disk around the black hole. Further, if there is indeed a delay in the X-ray emission we estimate the mass-transfer delivery radius to be ~1e11 cm.Comment: 9 pages, 2 figures, accepted for publication in ApJ
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