4,510 research outputs found

    Statistical evaluation of the flux cross-calibration of the XMM-Newton EPIC cameras

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    The second XMM-Newton serendipitous source catalogue, 2XMM, provides the ideal data base for performing a statistical evaluation of the flux cross-calibration of the XMM-Newton European Photon Imaging Cameras (EPIC). We aim to evaluate the status of the relative flux calibration of the EPIC cameras on board XMM-Newton (MOS1, MOS2, and pn) and investigate the dependence of the calibration on energy, position in the field of view of the X-ray detectors, and lifetime of the mission. We compiled the distribution of flux percentage differences for large samples of 'good quality' objects detected with at least two of the EPIC cameras. The mean offset of the fluxes and dispersion of the distributions was then found by Gaussian fitting. Count rate to flux conversion was performed with a fixed spectral model. The impact on the results of varying this model was investigated. Excellent agreement was found between the two EPIC MOS cameras to better than 4% from 0.2 keV to 12.0 keV. MOS cameras register 7-9% higher flux than pn below 4.5 keV and 10-13% flux excess above 4.5 keV. No evolution of the flux ratios is seen with time, except at energies below 0.5 keV, where we found a strong decrease in the MOS to pn flux ratio with time. This effect is known to be due to a gradually degrading MOS redistribution function. The flux ratios show some dependence on distance from the optical axis in the sense that the MOS to pn flux excess increases with off-axis angle. Furthermore, in the 4.5-12.0 keV band there is a strong dependence of the MOS to pn excess flux on the azimuthal-angle. These results strongly suggest that the calibration of the Reflection Grating Array (RGA) blocking factors is incorrect at high energies. Finally, we recommend ways to improve the calculation of fluxes in future versions of XMM-Newton source catalogues.Comment: 11 pages, 10 figures, 3 tables. Abridged Abstract. Accepted for publication in Astronomy and Astrophysic

    Collaborative Mapping of London Using Google Maps: The LondonProfiler

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    This paper begins by reviewing the ways in which the innovation of Google Maps has transformed our ability to reference and view geographically referenced data. We describe the ways in which the GMap Creator tool developed under the ESRC National Centre for E Social Science programme enables users to ‘mashup’ thematic choropleth maps using the Google API. We illustrate the application of GMap Creator using the example of www.londonprofiler.org, which makes it possible to view a range of health, education and other socioeconomic datasets against a backcloth of Google Maps data. Our conclusions address the ways in which Google Map mashups developed using GMap Creator facilitate online exploratory cartographic visualisation in a range of areas of policy concern

    Synopsis of a computer program designed to interface a personal computer with the fast data acquisition system of a time-of-flight mass spectrometer

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    Briefly described are the essential features of a computer program designed to interface a personal computer with the fast, digital data acquisition system of a time-of-flight mass spectrometer. The instrumentation was developed to provide a time-resolved analysis of individual vapor pulses produced by the incidence of a pulsed laser beam on an ablative material. The high repetition rate spectrometer coupled to a fast transient recorder captures complete mass spectra every 20 to 35 microsecs, thereby providing the time resolution needed for the study of this sort of transient event. The program enables the computer to record the large amount of data generated by the system in short time intervals, and it provides the operator the immediate option of presenting the spectral data in several different formats. Furthermore, the system does this with a high degree of automation, including the tasks of mass labeling the spectra and logging pertinent instrumental parameters

    Supervised physical activity during pregnancy improves fetal cardiac response

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    Objetivo: Valorar la influencia de un programa de ejercicio físico durante la gestación en la adaptación de la frecuencia cardiaca fetal (FCF). Se espera encontrar una mejor adaptación de la FCF especialmente en cuanto a recuperaciones más rápidas. Método: 45 gestantes participantes en un ensayo clínico aleatorizado sin complicaciones ni contraindicaciones para el ejercicio fueron estudiadas durante el tercer trimestre de embarazo. Se midieron las siguientes variables: FCF en reposo, FCF post-ejercicio y tiempo de recuperación de la FCF a los niveles de reposo. Resultados: La FCF en reposo fue similar en ambos grupos. La FCF post-ejercicio fue significativamente mayor en el grupo control (GC) que en el grupo ejercicio (GE) en ambas pruebas, al 40% GE=138,5±6,4GE vs 141±7,5 GC (p=0,001), al 60% 141,6±10,8 GE vs 150,3±16,8GC. Lo mismo ocurre en los tiempos de recuperación, al 40% 78,2±95,7GE vs 328,4±315,2GC (p=0,001), al 60% 193,3±257,8 GE vs 542,6±482,9GC (p=0,003). Conclusión: El ejercicio físico desarrollado durante el embarazo tiene como consecuencia una mejor adaptación de la FCF post-ejercicio, así como recuperaciones más rápidas.Objective: To assess the influence of a physical activity program during pregnancy on the adaptation of the fetal heart rate (FHR). Greater adaptations and faster recovery are expected to find. Methods: 45 pregnant women included in a randomized control trial, all with uncomplicated pregnancies for exercise were studied in their third trimester of pregnancy. Rest FHR, post-exercise FHR and recovery time were assessed. Results: Rest FHR was similar in both groups. Post-exercise FHR were significantly higher in control group (CG) than in exercise group (EG) in both test, 40% 138,5±6,4EG vs 141±7,5CG (p=0,001), 60% 141,6±10,8EG vs 150,3±16,8CG. The same was found in recovery time, 40% 78,2±95,7EG vs 328,4±315,2CG (p=0,001), al 60% 193,3±257,8EG vs 542,6±482,9CG (p=0,003)

    Supertubes in reduced holonomy manifolds

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    We show that the supertube configurations exist in all supersymmetric type IIA backgrounds which are purely geometrical and which have, at least, one flat direction. In other words, they exist in any spacetime of the form R^{1,1} x M_8, with M_8 any of the usual reduced holonomy manifolds. These generalised supertubes preserve 1/4 of the supersymmetries preserved by the choice of the manifold M_8. We also support this picture with the construction of their corresponding family of IIA supergravity backgrounds preserving from 1/4 to 1/32 of the total supercharges.Comment: 20 page

    Supersymmetric black rings and three-charge supertubes

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    We present supergravity solutions for 1/8-supersymmetric black supertubes with three charges and three dipoles. Their reduction to five dimensions yields supersymmetric black rings with regular horizons and two independent angular momenta. The general solution contains seven independent parameters and provides the first example of non-uniqueness of supersymmetric black holes. In ten dimensions, the solutions can be realized as D1-D5-P black supertubes. We also present a worldvolume construction of a supertube that exhibits three dipoles explicitly. This description allows an arbitrary cross-section but captures only one of the angular momenta.Comment: 59 pages, 6 figures; v2: minor correction
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