29 research outputs found

    WEBT multiwavelength monitoring and XMM-Newton observations of BL Lacertae in 2007-2008. Unveiling different emission components

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    In 2007-2008 we carried out a new multiwavelength campaign of the Whole Earth Blazar Telescope (WEBT) on BL Lacertae, involving three pointings by the XMM-Newton satellite, to study its emission properties. The source was monitored in the optical-to-radio bands by 37 telescopes. The brightness level was relatively low. Some episodes of very fast variability were detected in the optical bands. The X-ray spectra are well fitted by a power law with photon index of about 2 and photoelectric absorption exceeding the Galactic value. However, when taking into account the presence of a molecular cloud on the line of sight, the data are best fitted by a double power law, implying a concave X-ray spectrum. The spectral energy distributions (SEDs) built with simultaneous radio-to-X-ray data at the epochs of the XMM-Newton observations suggest that the peak of the synchrotron emission lies in the near-IR band, and show a prominent UV excess, besides a slight soft-X-ray excess. A comparison with the SEDs corresponding to previous observations with X-ray satellites shows that the X-ray spectrum is extremely variable. We ascribe the UV excess to thermal emission from the accretion disc, and the other broad-band spectral features to the presence of two synchrotron components, with their related SSC emission. We fit the thermal emission with a black body law and the non-thermal components by means of a helical jet model. The fit indicates a disc temperature greater than 20000 K and a luminosity greater than 6 x 10^44 erg/s.Comment: 11 pages, 7 figures, accepted for publication in A&

    Knowledge and innovation: The strings between global and local dimensions of sustainable growth

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    The modern growth literature pays much attention to innovation and knowledge as drivers of endogenous developments in a competitive open economic system. This paper reviews concisely the literature in this field and addresses in particular micro- and macro-economic interactions at local or regional levels, based on clustering and networking principles, in which sustainability conditions also play a core role. The paper then develops a so-called knowledge circuit model comprising the relevant stakeholders, which aims to offer a novel framework for applied policy research at the meso-economic level

    Sirtuin Deacetylases as Therapeutic Targets in the Nervous System

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    Faust-Symphonie; arr.

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    I. Faust -- II. Gretchen -- III. Mephistopheles

    Three piano pieces.

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    Title supplied by cataloger.A collection of 3 pieces for the piano, bound in 1 vol.Mode of access: Internet.Each of the 3 pieces has a handlettered inscription from Melchior Lechter to Marguerite Hoffmann, dated February 1926. The last p. of the 2nd piece has a decoration by Lechter

    Rechtsgrundlagen der Europäischen Einigung

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