458 research outputs found

    Disc-Jet coupling in the LMXB 4U1636-53 from INTEGRAL

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    We report on the spectral analysis results of the neutron star, atoll type, low mass X-ray Binary 4U1636-53 observed by INTEGRAL and BeppoSAX satellites. Spectral behavior in three different epochs corresponding to three different spectral states has been deeply investigated. Two data set spectra show a continuum well described by one or two soft blackbody plus a Comptonized components with changes in the Comptonizing electrons and black body temperature and the accretion rates, which are typical of the spectral transitions from high to low state. In one occasion INTEGRAL spectrum shows, for first time in this source, a hard tail dominating the emission above 30 keV. The total spectrum is fitted as the sum of a Comptonized component similar to soft state and a power-law component (Gamma=2.76), indicating the presence of a non thermal electron distribution of velocities. In this case, a comparison with hard tails detected in soft states from neutron stars systems and some black hole binaries suggests that a similar mechanism could originate these components in both cases.Comment: 6 pages, 4 figures, 2 tables. accepted Ap

    Swift-XRT observation of 34 new INTEGRAL/IBIS AGNs: discovery of Compton thick and other peculiar sources

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    For a significant number of the sources detected at high energies (>10 keV) by the INTEGRAL/IBIS and Swift/BAT instruments there is either a lack information about them in the 2-10 keV range or they are totally unidentified. Herein, we report on a sample of 34 IBIS AGN or AGN candidate objects for which there is X-ray data in the Swift/XRT archive. Thanks to these X-ray follow up observations, the identification of the gamma ray emitters has been possible and the spectral shape in terms of photon index and absorption has been evaluated for the first time for the majority of our sample sources. The sample, enlarged to include 4 more AGN already discussed in the literature, has been used to provide photon index and column density distribution. We obtain a mean value of 1.88 with a dispersion of 0.12, i.e. typical of an AGN sample. Sixteen objects (47%) have column densities in excess of 10^{22} cm^{-2} and, as expected, a large fraction of the absorbed sources are within the Sey 2 sample. We have provided a new diagnostic tool (NH versus F(2-10)keV/F(20-100)keV softness ratio) to isolate peculiar objects; we find at least one absorbed Sey 1 galaxy, 3 Compton thick AGN candidates; and one secure example of a "true" type 2 AGN. Within the sample of 10 still unidentified objects, 3 are almost certainly AGN of type 2; 3 to 4 have spectral slopes typical of AGN; and two are located high on the galactic plane and are strong enough radio emitters so that can be considered good AGN candidates.Comment: 15 pages, 5 figures, ApJ accepte

    Precautionary labelling of foods for allergen content: are we ready for a global framework?

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    © 2014 Allen et al.; licensee BioMed Central Ltd.Food allergy appears to be on the rise with the current mainstay of treatment centred on allergen avoidance. Mandatory allergen labelling has improved the safety of food for allergic consumers. However an additional form of voluntary labelling (termed precautionary allergen labelling) has evolved on a wide range of packaged goods, in a bid by manufacturers to minimise risk to customers, and the negative impact on business that might result from exposure to trace amounts of food allergen present during cross-contamination during production. This has resulted in near ubiquitous utilisation of a multitude of different precautionary allergen labels with subsequent confusion amongst many consumers as to their significance. The global nature of food production and manufacturing makes harmonisation of allergen labelling regulations across the world a matter of increasing importance. Addressing inconsistencies across countries with regards to labelling legislation, as well as improvement or even banning of precautionary allergy labelling are both likely to be significant steps forward in improved food safety for allergic families. This article outlines the current status of allergen labelling legislation around the world and reviews the value of current existing precautionary allergen labelling for the allergic consumer. We strongly urge for an international framework to be considered to help roadmap a solution to the weaknesses of the current systems, and discuss the role of legislation in facilitating this

    IGR J22517+2218=MG3 J225155+2217: a new gamma-ray lighthouse in the distant Universe

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    We report on the identification of a new soft gamma ray source, namely IGR J22517+2218, detected with IBIS/INTEGRAL. The source, which has an observed 20-100 keV flux of ~4 x10^-11 erg cm-2 s-1, is spatially coincident with MG3 J225155+2217, a quasar at z=3.668. The Swift/XRT 0.5-10 keV continuum is flat (Gamma=1.5) with evidence for a spectral curvature below 1-2 keV either due to intrinsic absorption (NH=3 +/- 2 x 10^22 cm-2) or to a change in slope (Delta Gamma= 0.5). X-ray observations indicate flux variability over a 6 days period which is further supported by a flux mismatch between Swift and INTEGRAL spectra. IGR J22517+2218 is radio loud and has a flat radio spectrum; optically it is a broad line emitting quasar with the atypical property of hosting a narrow line absorption system. The Source Spectral Energy Distribution is unusual compared to blazars of similar type: either it has the synchrotron peak in the X/gamma-ray band (i.e. much higher than generally observed) or the Compton peak in the MeV range (i.e. lower than typically measured). IGR J22517+2218=MG3 J225155+2217 is the second most distant blazar detected above 20 keV and a gamma-ray lighthouse shining from the edge of our Universe.Comment: 4 pages, 4 figures, Accepted for publication in Astrophysical Journal Letter

    BL Lacertae identifications in a ROSAT-selected sample of Fermi unidentified objects

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    The optical spectroscopic followup of 27 sources belonging to a sample of 30 high-energy objects selected by positionally cross correlating the first Fermi/LAT Catalog and the ROSAT All-Sky Survey Bright Source Catalog is presented here. It has been found or confirmed that 25 of them are BL Lacertae objects (BL Lacs), while the remaining two are Galactic cataclysmic variables (CVs). This strongly suggests that the sources in the first group are responsible for the GeV emission detected with Fermi, while the two CVs most likely represent spurious associations. We thus find an 80% a posteriori probability that the sources selected by matching GeV and X-ray catalogs belong to the BL Lac class. We also show suggestions that the BL Lacs selected with this approach are probably high-synchrotron-peaked sources and in turn good candidates for the detection of ultra-high-energy (TeV) photons from them.Comment: 16 pages, 9 figures, 4 tables, one appendix, accepted for publication on A&A, main journal. Tables 1-3 and Figures 2-6 will only be published in the electronic edition of the journa

    The 3rd IBIS/ISGRI soft gamma-ray survey catalog

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    In this paper we report on the third soft gamma-ray source catalog obtained with the IBIS/ISGRI gamma-ray imager on board the INTEGRAL satellite. The scientific dataset is based on more than 40 Ms of high quality observations performed during the first three and a half years of Core Program and public IBIS/ISGRI observations. Compared to previous IBIS/ISGRI surveys, this catalog includes a substantially increased coverage of extragalactic fields, and comprises more than 400 high-energy sources detected in the energy range 17-100 keV, including both transients and faint persistent objects which can only be revealed with longer exposure times.Comment: Accepted for publication in ApJ Suppl.; 11 pages; 4 figures Minor changes to conten

    The first detection of Compton Reflection in the Low-Mass X-ray Binary 4U1705-44 with INTEGRAL and BeppoSAX

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    We present data from INTEGRAL and BeppoSAX satellites showing spectral state transitions of the neutron-star, atoll-type, low-mass X-ray binary 1705-44. Its energy spectrum can be described as the sum of one or two blackbody components, a 6.4-keV Fe line, and a component due to thermal Comptonization. In addition, and for the first time in this source, we find a strong signature of Compton reflection, presumably due to illumination of the optically-thick accretion disk by the Comptonization spectrum. The two blackbody components, which the soft-state data require, presumably arise from both the disk and the neutron-star surface. The Comptonization probably takes place in a hot inner flow irradiated by some of the blackbody photons. The spectral transitions are shown to be associated with variations in the bolometric luminosity, most likely proportional to the accretion rate. Indipendentely from the spectral state, we also see changes in the temperature of the Comptonizing electrons and the strength of Compton reflection.Comment: accepted Ap

    Extracts of Feijoa Inhibit Toll-Like Receptor 2 Signaling and Activate Autophagy Implicating a Role in Dietary Control of IBD

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    Inflammatory bowel disease (IBD) is a heterogeneous chronic inflammatory disease affecting the gut with limited treatment success for its sufferers. This suggests the need for better understanding of the different subtypes of the disease as well as nutritional interventions to compliment current treatments. In this study we assess the ability of a hydrophilic feijoa fraction (F3) to modulate autophagy a process known to regulate inflammation, via TLR2 using IBD cell lines
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