2,879 research outputs found

    Standard spacecraft economic analysis. Volume 1: Executive summary

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    A study of the comparative program costs associated with use of various standardized spacecraft for Air Force space test program missions to be flown on the space shuttle during the 1980-1990 time period is reviewed. The first phase of the study considered a variety of procurement mixes composed of existing or programmed NASA standard spacecraft designs and a Air Force standard spacecraft design. The results were briefed to a joint NASA/Air Force audience on July 11, 1976. The second phase considered additional procurement options using an upgraded version of an existing NASA design. The results of both phases are summarized

    Standard spacecraft economic analysis. Volume 2: Findings and conclusions

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    The comparative program costs associated with use of various standardized spacecraft for Air Force space test program missions to be flown on the space shuttle were studied in two phases. In the first phase, a variety of procurement mixes composed of existing or programmed NASA standard spacecraft designs and an Air Force standard spacecraft design were considered. The second phase dealt with additional procurement options using an upgraded version of an existing NASA design. The results of both phases are discussed

    Protocol for a longitudinal qualitative interview study: maintaining psychological well-being in advanced cancer - what can we learn from patients' and carers' own coping strategies?

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    IntroductionPeople with advanced cancer and their carers experience stress and uncertainty which affects the quality of life and physical and mental health. This study aims to understand how patients and carers recover or maintain psychological well-being by exploring the strategies employed to self-manage stress and uncertainty.Methods and analysisA longitudinal qualitative interview approach with 30 patients with advanced cancer and 30 associated family or informal carers allows the exploration of contexts, mechanisms and outcomes at an individual level. Two interviews, 4–12?weeks apart, will not only enable the exploration of individuals’ evolving coping strategies in response to changing contexts but also how patients’ and carers’ strategies inter-relate. Patient and Carer focus groups will then consider how the findings may be used in developing an intervention. Recruiting through two major tertiary cancer centres in the North West and using deliberately broad and inclusive criteria will enable the sample to capture demographic and experiential breadth.Ethics and disseminationThe research team will draw on their considerable experience to ensure that the study is sensitive to a patient and carer group, which may be considered vulnerable but still values being able to contribute its views. Public and patient involvement (PPI) is integral to the design and is evidenced by: a research advisory group incorporating patient and carers, prestudy consultations with the PPI group at one of the study sites and a user as the named applicant. The study team will use multiple methods to disseminate the findings to clinical, policy and academic audiences. A key element will be engaging health professionals in patient and carer ideas for promoting self-management of psychological well-being. The study has ethical approval from the North West Research Ethics Committee and the appropriate NHS governance clearance.RegistrationNational Institute for Health Research (NIHR) Clinical Studies Portfolio, UK Clinical Research Network (UKCRN) Study number 11725

    SUMSS: A Wide-Field Radio Imaging Survey of the Southern Sky. I. Science goals, survey design and instrumentation

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    The Molonglo Observatory Synthesis Telescope, operating at 843 MHz with a 5 square degree field of view, is carrying out a radio imaging survey of the sky south of declination -30 deg. This survey (the Sydney University Molonglo Sky Survey, or SUMSS) produces images with a resolution of 43" x 43" cosec(Dec.) and an rms noise level of about 1 mJy/beam. SUMSS is therefore similar in sensitivity and resolution to the northern NRAO VLA Sky Survey (NVSS; Condon et al. 1998). The survey is progressing at a rate of about 1000 square degrees per year, yielding individual and statistical data for many thousands of weak radio sources. This paper describes the main characteristics of the survey, and presents sample images from the first year of observation.Comment: 27 pages, 12 figures (figures 2, 8, 10 in jpg format); AJ, in pres

    The Molonglo Galactic Plane Survey: I. Overview and Images

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    The first epoch Molonglo Galactic Plane Survey (MGPS1) is a radio continuum survey made using the Molonglo Observatory Synthesis Telescope (MOST) at 843 MHz with a resolution of 43" X 43" cosec |delta|. The region surveyed is 245 deg < l < 355 deg, |b| < 1.5 deg. The thirteen 9 deg X 3 deg mosaic images presented here are the superposition of over 450 complete synthesis observations, each taking 12 h and covering 70' X 70' cosec |delta|. The root-mean-square sensitivity over much of the mosaiced survey is 1-2 mJy/beam (1 sigma), and the positional accuracy is approximately 1" X 1" cosec |delta| for sources brighter than 20 mJy. The dynamic range is no better than 250:1, and this also constrains the sensitivity in some parts of the images. The survey area of 330 sq deg contains well over 12,000 unresolved or barely resolved objects, almost all of which are extra-galactic sources lying in the Zone of Avoidance. In addition a significant fraction of this area is covered by extended, diffuse emission associated with thermal complexes, discrete H II regions, supernova remnants, and other structures in the Galactic interstellar medium.Comment: Paper with 3 figures and 1 table + Table 2 + 7 jpg grayscales for Fig 4. Astrophysical Journal Supplement (in press) see also http://www.astrop.physics.usyd.edu.au/MGP

    ATPMN: accurate positions and flux densities at 5 and 8 GHz for 8,385 sources from the PMN survey

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    We present a source catalogue of 9,040 radio sources resulting from high-resolution observations of 8,385 PMN sources with the Australia Telescope Compact Array. The catalogue lists flux density and structural measurements at 4.8 and 8.6 GHz, derived from observations of all PMN sources in the declination range -87 deg < delta < -38.5 deg (exclusive of galactic latitudes |b| 70 mJy (50 mJy south of delta = -73 deg). We assess the quality of the data, which was gathered in 1992-1994, describe the population of catalogued sources, and compare it to samples from complementary catalogues. In particular we find 127 radio sources with probable association with gamma-ray sources observed by the orbiting Fermi Large Area Telescope.Comment: 20 pages, 21 figure

    Faraday Rotation as a diagnostic of Galactic foreground contamination of CMB maps

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    The contribution from the residuals of the foreground can have a significant impact on the temperature maps of the Cosmic Microwave Background (CMB). Mostly, the focus has been on the galactic plane, when foreground cleaning has taken place. However, in this paper, we will investigate the possible foreground contamination, from sources outside the galactic plane in the CMB maps. We will analyze the correlation between the Faraday rotation map and the CMB temperature map. The Faraday rotation map is dependent on the galactic magnetic field, as well as the thermal electron density, and both may contribute to the CMB temperature. We find that the standard deviation for the mean cross correlation deviate from that of simulations at the 99.9% level. Additionally, a comparison between the CMB temperature extrema and the extremum points of the Faraday rotation is also performed, showing a general overlap between the two. Also we find that the CMB Cold Spot is located at an area of strong negative cross correlation, meaning that it may be explained by a galactic origin. Further, we investigate nearby supernova remnants in the galaxy, traced by the galactic radio loops. These super nova remnants are located at high and low galactic latitude, and thus well outside the galactic plane. We find some correlation between the Faraday Rotation and the CMB temperature, at select radio loops. This indicate, that the galactic foregrounds may affect the CMB, at high galactic latitudesComment: 13 pages, 22 figures, 6 table

    Black-holes, topological strings and large N phase transitions

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    The counting of microstates of BPS black-holes on local Calabi-Yau of the form O(p2)O(p)S2{\mathcal O}(p-2)\oplus{\mathcal O}(-p) \longrightarrow S^2 is explored by computing the partition function of q-deformed Yang-Mills theory on S2S^2. We obtain, at finite NN, the instanton expansion of the gauge theory. It can be written exactly as the partition function for U(N) Chern-Simons gauge theory on a Lens space, summed over all non-trivial vacua, plus a tower of non-perturbative instanton contributions. In the large NN limit we find a peculiar phase structure in the model. At weak string coupling the theory reduces to the trivial sector and the topological string partition function on the resolved conifold is reproduced in this regime. At a certain critical point, instantons are enhanced and the theory undergoes a phase transition into a strong coupling regime. The transition from the strong coupling phase to the weak coupling phase is of third order.Comment: 16 pages, 3 figures; Invited talk given at QG05, Cala Gonone (Italy), September 200

    Constriction size distributions of granular filters: a numerical study

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    The retention capability of granular filters is controlled by the narrow constrictions connecting the voids within the filter. The theoretical justification for empirical filter rules used in practice includes consideration of an idealised soil fabric in which constrictions form between co-planar combinations of spherical filter particles. This idealised fabric has not been confirmed by experimental or numerical observations of real constrictions. This paper reports the results of direct, particle-scale measurement of the constriction size distribution (CSD) within virtual samples of granular filters created using the discrete-element method (DEM). A previously proposed analytical method that predicts the full CSD using inscribed circles to estimate constriction sizes is found to poorly predict the CSD for widely graded filters due to an over-idealisation of the soil fabric. The DEM data generated are used to explore quantitatively the influence of the coefficient of uniformity, particle size distribution and relative density of the filter on the CSD. For a given relative density CSDs form a narrow band of similarly shaped curves when normalised by characteristic filter diameters. This lends support to the practical use of characteristic diameters to assess filter retention capability
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