7,455 research outputs found
The detection and photometric redshift determination of distant galaxies using SIRTF's Infrared Array Camera
We investigate the ability of the Space Infrared Telescope Facility's
Infrared Array Camera to detect distant (z ~ 3)galaxies and measure their
photometric redshifts. Our analysis shows that changing the original long
wavelength filter specifications provides significant improvements in
performance in this and other areas.Comment: 28 pages incl 12 figures; to appear in June 1999 PASP. Fig.12
replaced with corrected versio
Bringing genetics into primary care: findings from a national evaluation of pilots in England
Objectives: Developments in genetic knowledge and clinical applications are seen as rendering traditional modes of organizing genetics provision increasingly inappropriate. In common with a number of developed world countries the UK has sought to increase the role of primary care in delivering such services. However, efforts to reconfigure service delivery face multiple challenges associated with divergent policy objectives, organizational boundaries and professional cultures. This paper presents findings from an evaluation of an English initiative to integrate genetics into 'mainstream' clinical provision in the National Health Service. Methods: Qualitative research in 11 case-study sites focusing on attempts by pilots funded by the initiative to embed knowledge and provision within primary care illustrating barriers faced and the ways in which these were surmounted. Results: Lack of intrinsic interest in clinical genetics among primary care staff was compounded by national targets that focused their attention elsewhere and by service structures that rendered genetics a peripheral concern demanding minimal engagement. Established divisions between the commissioning of mainstream and specialist services, along with the pressures of shorter-term targets, impeded ongoing funding. Conclusions: More wide-ranging policy and organizational support is required if the aim of entrenching genetics knowledge and practice across the Health Service is to be realized
The Porcupine Survey: A Distributed Survey and WISE Followup
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
Evaluating Maintainability Prejudices with a Large-Scale Study of Open-Source Projects
Exaggeration or context changes can render maintainability experience into
prejudice. For example, JavaScript is often seen as least elegant language and
hence of lowest maintainability. Such prejudice should not guide decisions
without prior empirical validation. We formulated 10 hypotheses about
maintainability based on prejudices and test them in a large set of open-source
projects (6,897 GitHub repositories, 402 million lines, 5 programming
languages). We operationalize maintainability with five static analysis
metrics. We found that JavaScript code is not worse than other code, Java code
shows higher maintainability than C# code and C code has longer methods than
other code. The quality of interface documentation is better in Java code than
in other code. Code developed by teams is not of higher and large code bases
not of lower maintainability. Projects with high maintainability are not more
popular or more often forked. Overall, most hypotheses are not supported by
open-source data.Comment: 20 page
Multiple case-study analysis of quality management practices within UK Six Sigma and non-Six Sigma manufacturing small- and medium-sized enterprises
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
Quantifying CO 2 Insertion Equilibria for Low-Pressure Propene Oxide and Carbon Dioxide Ring Opening Copolymerization Catalysts
While outstanding catalysts are known for the ring-opening copolymerization (ROCOP) of CO2 and propene oxide (PO), few are reported at low CO2 pressure. Here, a new series of CoÂ(III)ÂMÂ(I) heterodinuclear catalysts are compared. The CoÂ(III)ÂKÂ(I) complex shows the best activity (TOF = 1728 h–1) and selectivity (>90% polymer, >99% CO2) and is highly effective at low pressures (<10 bar). CO2 insertion is a prerate determining chemical equilibrium step. At low pressures, the concentration of the active catalyst depends on CO2 pressure; above 12 bar, its concentration is saturated, and rates are independent of pressure, allowing the equilibrium constant to be quantified for the first time (K eq = 1.27 M–1). A unified rate law, applicable under all operating conditions, is presented. As proof of potential, published data for leading literature catalysts are reinterpreted and the CO2 equilibrium constants estimated, showing that this unified rate law applies to other systems
WISE Brown Dwarf Binaries: The Discovery of a T5+T5 and a T8.5+T9 System
The multiplicity properties of brown dwarfs are critical empirical constraints for formation theories, while multiples themselves provide unique opportunities to test evolutionary and atmospheric models and examine empirical trends. Studies using high-resolution imaging cannot only uncover faint companions, but they can also be used to determine dynamical masses through long-term monitoring of binary systems. We have begun a search for the coolest brown dwarfs using preliminary processing of data from the Wide-field Infrared Survey Explorer and have confirmed many of the candidates as late-type T dwarfs. In order to search for companions to these objects, we are conducting observations using the Laser Guide Star Adaptive Optics system on Keck II. Here we present the first results of that search, including a T5 binary with nearly equal mass components and a faint companion to a T8.5 dwarf with an estimated spectral type of T9
SPICES II. Optical and Near-Infrared Identifications of Faint X-Ray Sources from Deep Chandra Observations of Lynx
We present our first results on field X-ray sources detected in a deep, 184.7
ks observation with the ACIS-I camera on Chandra. The observations target the
Lynx field of SPICES, and contains three known X-ray-emitting clusters out to
z=1.27. Not including the known clusters, in the 17'x17' ACIS-I field we detect
132 sources in the 0.5-2 keV (soft) X-ray band down to a limiting flux of
\~1.7e-16 erg/cm2/s and 111 sources in the 2-10 keV (hard) X-ray band down to a
limiting flux of ~1.3e-15 erg/cm2/s. The combined catalog contains a total of
153 sources, of which 42 are detected only in the soft band and 21 are detected
only in the hard band. Confirming previous Chandra results, we find that the
fainter sources have harder X-ray spectra, providing a consistent solution to
the long-standing `spectral paradox'. From deep optical and near-infrared
follow-up data, 77% of the X-ray sources have optical counterparts to I=24 and
71% of the X-ray sources have near-infrared counterparts to K=20. Four of the
24 sources in the near-IR field are associated with extremely red objects
(EROs; I-K>4). We have obtained spectroscopic redshifts with the Keck
telescopes of 18 of the Lynx Chandra sources. These sources comprise a mix of
broad-lined active galaxies, apparently normal galaxies, and two late-type
Galactic dwarfs. Intriguingly, one Galactic source is identified with an M7
dwarf exhibiting non-transient, hard X-ray emission. We review non-AGN
mechanisms to produce X-ray emission and discuss properties of the Lynx Chandra
sample in relation to other samples of X-ray and non-X-ray sources.Comment: 42 pages, 16 figures. Accepted for publication in the May 2002
Astronomical Journa
Resist, comply or workaround? An examination of different facets of user engagement with information systems
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
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