2,652 research outputs found

    Removing sky contributions from SCUBA data

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    The Submillimetre Common-User Bolometer Array (SCUBA) is a new continuum camera operating on the James Clerk Maxwell Telescope (JCMT) on Mauna Kea, Hawaii. It consists of two arrays of bolometric detectors; a 91 pixel 350/450 micron array and a 37 pixel 750/850 micron array. Both arrays can be used simultaneously and have a field-of-view of approximately 2.4 arcminutes in diameter on the sky. Ideally, performance should be limited solely by the photon noise from the sky background at all wavelengths of operation. However, observations at submillimetre wavelengths are hampered by ``sky-noise'' which is caused by spatial and temporal fluctuations in the emissivity of the atmosphere above the telescope. These variations occur in atmospheric cells that are larger than the array diameter, and so it is expected that the resultant noise will be correlated across the array and, possibly, at different wavelengths. In this paper we describe our initial investigations into the presence of sky-noise for all the SCUBA observing modes, and explain our current technique for removing it from the data.Comment: 11 pages, 16 figures, Proc SPIE vol 335

    Austrian development policy - from global to neighbourhood policy?

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    When Austria joined the EU in 1995, it was expected that the Austrian government would increase the Official Development Assistance (ODA) budget and organise their aid management more in line with European and international standards. There was thus an expectation that Austria would witness a Europeanization of its development policy. Looking at the situation after 20 years of membership, it seems that Austria took on board the European development rhetoric without a significant increase of the overall ODA budget. Although a more professional Austrian Development Agency (ADA) has been established, ODA is still focused more on neighbourhood policy in the Western Balkans and in promoting foreign trade interests in the Caucasus region than on poverty reduction in the global south and in delivering contributions to the global public goods. Due to the lack of a strong binding acquis, Austria has been able to hide under the umbrella of an European Development policy with development rhetoric and some adjustment of implementing structures without any significant financial disbursements

    Comparison of Two Types of Mouse Running Wheels.

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    Voluntary wheel running of mice has been used as a measure of physical activity in a multitude of studies. The aim of this study was to validate low profile wireless running wheels (Med Associates Inc.) against solid-surface, traditionally-mounted vertical running wheels. All animal procedures were approved by the Texas A &M IACUC. Eleven week old female C57BL/6J mice (Jackson Labs, Bar Harbor, ME) were randomly assigned to either vertical running wheels (n=5) or low profile running wheels (n=5). Daily distance run was monitored for 12 days following initial wheel orientation exposure. Average daily distance run by the mice was not different (p=0.37) between the two types of wheels, with the mice on vertical wheels averaging 6.74(±1.74 km/day; average ±SD) versus 8.58(±1.87km/day) on the low profile wheels. The distance run by the mice on the low profile wheels was also compared to the distance the same mice ran on the vertical wheels (8.6±1.04 km/day; p=0.96). Thus data collected on the low-profile wheels was similar to the vertical running wheels not only among two age and sex-matched groups of mice, but also when the same group of mice ran on the two wheel types. However, on the low-profile wheels, the inability to measure duration of wheel running due to software limitations of the data-collection bin size eliminates the calculation of running speed, both of which are important phenotypes of physical activity. Additionally, there were also numerous observations of the mice coasting on the low-profile wheels, an issue not present on the traditional, solid-surface wheels. The presence of coasting would inflate distance measures over true measures of activity and may have been responsible for the non-significant elevation of distance on the low-profile wheels. Thus, if accurate measures of distance or measurement of duration and speed are not required, the low-profile wheel is a valid methodology

    Structural and dielectric studies of the phase behaviour of the topological ferroelectric La1-xNdxTaO4

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    We thank the University of St Andrews and EPSRC (via DTG studentships to CALD and JG) for funding,The layered perovskite LaTaO4 has been prepared in its polar orthorhombic polymorphic form at ambient temperature. Although no structural phase transition is observed in the temperature interval 25° C < T < 500 °C, a very large axial thermal contraction effect is seen, which can be ascribed to an anomalous buckling of the perovskite octahedral layer. The non-polar monoclinic polymorph can be stabilised at ambient temperature by Nd-doping. A composition La0.90Nd0.10TaO4 shows a first-order monoclinic-orthorhombic (non-polar to polar) transition in the region 250° C < T < 350 °C. Dielectric responses are observed at both the above structural events but, despite the ‘topological ferroelectric’ nature of orthorhombic LaTaO4, we have not succeeded in obtaining ferroelectric P–E hysteresis behaviour. Structural relationships in the wider family of AnBnX3n+2 layered perovskites are discussed.Publisher PDFPeer reviewe

    SCUBA - A submillimetre camera operating on the James Clerk Maxwell Telescope

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    The Submillimetre Common-User Bolometer Array (SCUBA) is one of a new generation of cameras designed to operate in the submillimetre waveband. The instrument has a wide wavelength range covering all the atmospheric transmission windows between 300 and 2000 microns. In the heart of the instrument are two arrays of bolometers optimised for the short (350/450 microns) and long (750/850 microns) wavelength ends of the submillimetre spectrum. The two arrays can be used simultaneously, giving a unique dual-wavelength capability, and have a 2.3 arc-minute field of view on the sky. Background-limited performance is achieved by cooling the arrays to below 100 mK. SCUBA has now been in active service for over a year, and has already made substantial breakthroughs in many areas of astronomy. In this paper we present an overview of the performance of SCUBA during the commissioning phase on the James Clerk Maxwell Telescope (JCMT).Comment: 14 pages, 13 figures (1 JPEG), Proc SPIE vol 335

    Beyond theory:an examination of lean new product introduction practices in the UK

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    Interest is growing around the application of lean techniques to new product introduction (NPI). Although a relatively emergent topic compared with the application of ‘lean’ within the factory, since 2000 there has been an exponential rise in the literature on this subject. However, much of this work focuses on describing and extolling the virtues of the ‘Toyota approach’ to design. Therefore, by way of a stock take for the UK, the present authors' research has set out to understand how well lean product design practices have been adopted by leading manufacturers. This has been achieved by carrying out in-depth case studies with three carefully selected manufacturers of complex engineered products. This paper describes these studies, the detailed results and subsequent findings, and concludes that both the awareness and adoption of practices is generally embryonic and far removed from the theory advocated in the literature

    Selection of polymer binders and fabrication of SiC fiber-reinforced reaction-bonded silicon nitride matrix composites

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    The topics discussed include the following: effects of solvent and polymer exposures on nitriding kinetics of high purity Si powders and on resulting phase distributions; effects of solvent and polymer exposures on Si Surface Chemistry; effects of solvent and polymeric exposures on nitriding kinetics; and fabrication of flexural test samples
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