6,612 research outputs found

    The Porcupine Survey: A Distributed Survey and WISE Followup

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    Spitzer post-cryogen observations to perform a moderate depth survey distributed around the sky are proposed. Field centers are chosen to be WISE brown dwarf candidates, which will typically be 160 µJy at 4.7 µm and randomly distributed around the sky. The Spitzer observations will give much higher sensitivity, higher angular resolution, and a time baseline to measure both proper motions and possibly parallaxes. The distance and velocity data obtained on the WISE brown dwarf candidates will greatly improve our knowledge of the mass and age distribution of brown dwarfs. The outer parts of the Spitzer fields surrounding the WISE positions will provide a deep survey in many narrow fields of view distributed around the sky, and the volume of this survey will contain many more distant brown dwarfs, and many extragalactic objects

    Multiple case-study analysis of quality management practices within UK Six Sigma and non-Six Sigma manufacturing small- and medium-sized enterprises

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    This paper examines multiple case-study analysis of quality management practices within UK Six Sigma and non-Six Sigma manufacturing small- and medium-sized enterprises

    So you call that research? : mending methodological biases in strategy and organization departments of top business schools

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    We believe that all strategy and organization (SO) scholars should be able to decide for themselves whether to specialize in certain parts of the knowledge cycle or adopt a broader, multi-method view on the scientific process. In a situation of ―methodological pluralism‖, individuals might choose to contribute to the construction of new administrative theories by means of qualitative works like case studies, ethnographies, biographies, or grounded theory studies (e.g., see Denzin and Lincoln, 2000). Others could then specialize in testing these theories by means of experiments, surveys, or longitudinal econometric studies (e.g., see Lewis-Beck, 1987-2004). Again others could combine both approaches in Herculean attempts to conduct high-impact, integrative research with the potential to change the way we understand the field as a whole

    Resist, comply or workaround? An examination of different facets of user engagement with information systems

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    This paper provides a summary of studies of user resistance to Information Technology (IT) and identifies workaround activity as an understudied and distinct, but related, phenomenon. Previous categorizations of resistance have largely failed to address the relationships between the motivations for divergences from procedure and the associated workaround activity. This paper develops a composite model of resistance/workaround derived from two case study sites. We find four key antecedent conditions derived from both positive and negative resistance rationales and identify associations and links to various resultant workaround behaviours and provide supporting Chains of Evidence from two case studies

    The First Ultra-cool Brown Dwarf Discovered by the Wide-field Infrared Survey Explorer

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    We report the discovery of the first new ultra-cool brown dwarf (BDs) found with the Wide-field Infrared Survey Explorer (WISE). The object’s preliminary designation is WISEPC J045853.90+643451.9. Follow-up spectroscopy with the LUCIFER instrument on the Large Binocular Telescope indicates that it is a very late-type T dwarf with a spectral type approximately equal to T9. Fits to an IRTF/SpeX 0.8–2.5 μm spectrum to the model atmospheres of Marley and Saumon indicate an effective temperature of approximately 600 K as well as the presence of vertical mixing in its atmosphere. The new BD is easily detected by WISE, with a signal-to-noise ratio of ~36 at 4.6 μm. Current estimates place it at a distance of 6–10 pc. This object represents the first in what will likely be hundreds of nearby BDs found by WISE that will be suitable for follow-up observations, including those with the James Webb Space Telescope. One of the two primary scientific goals of the WISE mission is to find the coolest, closest stars to our Sun; the discovery of this new BD proves that WISE is capable of fulfilling this objective

    Deep mid-infrared observations of Lyman-break galaxies

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    As part of the In-Orbit Checkout activities for the Spitzer Space Telescope, the IRAC team carried out a deep observation (average integration time ~8 hours) of a field surrounding the bright QSO HS 1700+6416. This field contains several hundred z~3 Lyman-break galaxy candidates, and we report here on their mid-infrared properties, including the IRAC detection rate, flux densities and colors, and the results of fitting population synthesis models to the optical, near-infrared, and IRAC magnitudes. The results of the model-fitting show that previous optical/near-infrared studies of LBGs were not missing large, hidden old stellar populations. The LBG candidates' properties are consistent with those of massive, star-forming galaxies at z~3. Other IRAC sources in the same field have similar properties, so IRAC selection may prove a promising method of finding additional high-redshift galaxies.Comment: ApJS in press (Spitzer special issue); 13 pages, 3 figure

    HST Morphologies of z~2 Dust Obscured Galaxies I: Power-law Sources

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    We present high spatial resolution optical and near-infrared imaging obtained using the ACS, WFPC2 and NICMOS cameras aboard the Hubble Space Telescope of 31 24um--bright z~2 Dust Obscured Galaxies (DOGs) identified in the Bootes Field of the NOAO Deep Wide-Field Survey. Although this subset of DOGs have mid-IR spectral energy distributions dominated by a power-law component suggestive of an AGN, all but one of the galaxies are spatially extended and not dominated by an unresolved component at rest-frame UV or optical wavelengths. The observed V-H and I-H colors of the extended components are 0.2-3 magnitudes redder than normal star-forming galaxies. All but 1 have axial ratios >0.3, making it unlikely that DOGs are composed of an edge-on star-forming disk. We model the spatially extended component of the surface brightness distributions of the DOGs with a Sersic profile and find effective radii of 1-6 kpc. This sample of DOGs is smaller than most sub-millimeter galaxies (SMGs), but larger than quiescent high-redshift galaxies. Non-parametric measures (Gini and M20) of DOG morphologies suggest that these galaxies are more dynamically relaxed than local ULIRGs. We estimate lower limits to the stellar masses of DOGs based on the rest-frame optical photometry and find that these range from ~10^(9-11) M_sun. If major mergers are the progenitors of DOGs, then these observations suggest that DOGs may represent a post-merger evolutionary stage.Comment: 23 pages, 9 figures, 6 tables, accepted to ApJ; lower limits on stellar mass revised upwards by factor of (1+z
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