2,500 research outputs found

    New insular taxa from the oldest Terre Rosse fissure filling (Gargano, Southeastern Italy).

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    A rich amount of fossil remains of a highly diversified vertebrate fauna, known as “Mikrotia fauna”, has been retrieved from the red soil deposits (Terre Rosse) which fill the extensive palaeokarst network that affects the Mesozoic limestone along the north-western slopes of Mount Gargano (Southern Italy). The faunal assemblages reveal a rather complex history of bioevents such as dispersals and extinctions, which occurred when the area was isolated. These reconstructions were based on the materials collected during the seventies and the eighties of the last century. Forty years after its discovery, the Gargano Terre Rosse finally yielded evidence of an older faunal settlement. The peculiar assemblage of the M013 fissure allows to explain some of the controversial aspects of the Gargano faunal history, namely, the matter of the biochronology of the older fissure fillings and the issue of the arrivals of the taxa in the insular domain. The taxonomic study of the small mammal assemblage from fissure M013, sampled by a team of the University of Torino during the 2005-09 excavations in the Dell’Erba Quarry (Apricena, Foggia), is here presented. Insectivores include a small-sized endemic Galericinae Apulogalerix cf. pusillus, together with a Crocidosoricinae, Lartetium cf. dehmi. Gliridae are well represented by the endemic species Stertomys simplex and S.lyrifer. Cricetids (l.s.) are represented by a single remain belonging to the endemic Hattomys cf. nazarii, but also by a new genus and species of an endemic and rather primitive Cricetodontinae. The latter shows a very hypsodont dental crown, stocky cusps and tubercle-like crests. Some of its features are typical of the continental genera of Cricetodontinae (i.e. large size, thick and crenulated enamel), however the very large size and the very high hypsodonty indicate the endemic nature of this taxon. The occlusal pattern appears rather primitive due to the very low, poorly developed, interrupted ectolophs and share some features with the primitive species of the genus Cricetodon. Murids include Mikrotia parva together with a second larger species, which is not yet identified. A third Murinae rodent is quite abundant, and belongs to a new genus and species. Its dentition is more brachyodont than in Mikrotia parva, the upper teeth are stephanodont and, accordingly, the transversal crests are joined by a longitudinal crest in the lower molars. Tubercle t7 is absent in the upper molars, t2bis is always present, while t1bis is usually absent in the first upper molar. Tubercle t1 is placed in a distal position respect to the t3, the posterolabial tubercle t12 is well-developed. Tubercles t3, t6 and t9 are roughly equidistant forming a regular pattern: a character that is found in Mikrotia and not in the other murid species, in which t6 is closer to t9. This morphological characters reveal a close relationship with Mikrotia, but they do not occur jointly in any of the Late Miocene-Earliest Pliocene European genera of murids, thus the phylogenetic origin of this new genus is still unclear. The occurrence of this new Murinae and of a Cricetodontinae distinguishes M013 from all the other Terre Rosse fissure fillings of Gargano. Stertomys lyrifer and S. simplex were previously known only from the very ancient fissure Rinascita 1. Because both taxa characterize M013 and Rinascita 1, the two fissures are believed to be very close chronologically. Also the Crocidosoricinae characterises the older fissure fillings. In contrast, M013 is the only fissure lacking Apodemus and Prolagus, which are otherwise present in all the other Gargano infillings. The accumulated evidence indicates M013 as the oldest of Gargano’s faunal assemblages, despite the occurrence of Hattomys cf. nazarii, Mikrotia cf. parva and Mikrotia sp1, which most probably results from infiltrations from younger fissure fillings. The M013 assemblage is an absolute novelty for the Abruzzo-Apulian Palaeobioprovince and opens a new perspectives for the timing and mode of dispersal of the forerunners of the Gargano fauna

    Water adsorption on amorphous silica surfaces: A Car-Parrinello simulation study

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    A combination of classical molecular dynamics (MD) and ab initio Car-Parrinello molecular dynamics (CPMD) simulations is used to investigate the adsorption of water on a free amorphous silica surface. From the classical MD SiO_2 configurations with a free surface are generated which are then used as starting configurations for the CPMD.We study the reaction of a water molecule with a two-membered ring at the temperature T=300K. We show that the result of this reaction is the formation of two silanol groups on the surface. The activation energy of the reaction is estimated and it is shown that the reaction is exothermic.Comment: 12 pages, 6 figures, to be published in J. Phys.: Condens. Matte

    Validity and reliability of the Structured Clinical Interview for Depersonalization-Derealization Spectrum (SCI-DER).

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    This study evaluates the validity and reliability of a new instrument developed to assess symptoms of depresonalization: the Structured Clinical Interview for the Depersonalization-Derealization Spectrum (SCI-DER). The instrument is based on a spectrum model that emphasizes soft-signs, sub-threshold syndromes as well as clinical and subsyndromal manifestations. Items of the interview include, in addition to DSM-IV criteria for depersonalization, a number of features derived from clinical experience and from a review of phenomenological descriptions. Study participants included 258 consecutive patients with mood and anxiety disorders, 16.7% bipolar I disorder, 18.6% bipolar II disorder, 32.9% major depression, 22.1% panic disorder, 4.7% obsessive compulsive disorder, and 1.5% generalized anxiety disorder; 2.7% patients were also diagnosed with depersonalization disorder. A comparison group of 42 unselected controls was enrolled at the same site. The SCI-DER showed excellent reliability and good concurrent validity with the Dissociative Experiences Scale. It significantly discriminated subjects with any diagnosis of mood and anxiety disorders from controls and subjects with depersonalization disorder from controls. The hypothesized structure of the instrument was confirmed empirically

    The NuSTAR Extragalactic Surveys: unveiling rare, buried AGNs and detecting the contributors to the peak of the Cosmic X-ray Background

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    We report on the results of active galactic nuclei (AGNs) detection by NuSTAR performed in three extragalactic survey fields (COSMOS, UDS, ECDFS) in three hard bands, namely H1 (8-16 keV), H2 (16-24 keV) and VH (35-55 keV). The aggregated area of the surveys is 2.7\sim 2.7 deg2^2. While a large number of sources is detected in the H1 band (72 at the 97%97\% level of reliability), the H2 band directly probing close to the peak of the Cosmic X-ray Background (CXB) returns four significant detections, and two tentative, although not significant, detections are found in the VH band. All the sources detected above 16 keV are also detected at lower energies. We compute the integral number counts for sources in such bands, which show broad consistency with population synthesis models of the CXB. We furthermore identify two Compton-thick AGNs, one in the COSMOS field, associated with a hard and faint Chandra source, and one in the UDS field, never detected in the X-ray band before. Both sources are at the same redshift z1.25z \sim 1.25, which shifts their Compton-hump into the H1 band, and were previously missed in the usually employed NuSTAR bands, confirming the potential of using the H1 band to discover obscured AGNs at z>1z > 1 in deep surveys.Comment: 12 pages, 5 figures, accepted for publication in The Astrophysical Journa

    A growth-rate indicator for Compton-thick active galactic nuclei

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    Due to their heavily obscured central engines, the growth rate of Compton-thick (CT) active galactic nuclei (AGN) is difficult to measure. A statistically significant correlation between the Eddington ratio, {\lambda}Edd_{Edd}, and the X-ray power-law index, {\Gamma}, observed in unobscured AGN offers an estimate of their growth rate from X-ray spectroscopy (albeit with large scatter). However, since X-rays undergo reprocessing by Compton scattering and photoelectric absorption when the line-of-sight to the central engine is heavily obscured, the recovery of the intrinsic {\Gamma} is challenging. Here we study a sample of local, predominantly Compton-thick megamaser AGN, where the black hole mass, and thus Eddington luminosity, are well known. We compile results on X-ray spectral fitting of these sources with sensitive high-energy (E> 10 keV) NuSTAR data, where X-ray torus models which take into account the reprocessing effects have been used to recover the intrinsic {\Gamma} values and X-ray luminosities, LX_X. With a simple bolometric correction to LX_X to calculate {\lambda}Edd_{Edd}, we find a statistically significant correlation between {\Gamma} and {\lambda}Edd_{Edd} (p = 0.007). A linear fit to the data yields {\Gamma} = (0.41±\pm0.18)log10_{10}{\lambda}Edd_{Edd}+(2.38±\pm 0.20), which is statistically consistent with results for unobscured AGN. This result implies that torus modeling successfully recovers the intrinsic AGN parameters. Since the megamasers have low-mass black holes (MBH106107_{BH}\approx10^6-10^7 Msol_{sol}) and are highly inclined, our results extend the {\Gamma}-{\lambda}Edd_{Edd} relationship to lower masses and argue against strong orientation effects in the corona, in support of AGN unification. Finally this result supports the use of {\Gamma} as a growth-rate indicator for accreting black holes, even for Compton-thick AGN.Comment: Accepted for publication in Ap

    Georadar investigations to detect cavities in a historical town damaged by an earthquake of the past

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    This paper aims to highlight the use of the georadar as a useful prospecting technique to identify the areal density and the geometrical features of the grottoes placed in a historical town characterised by high seismic hazard. <br><br> The town considered here is Rionero in Vulture (Southern Italy) that was hit by several historical earthquakes, among which the 1930 Irpinia earthquake (Me=6.7, Is=VIII MCS). <br><br> For this event a damage map was already available from a previous study (Gizzi and Masini, 2006). This map shows that some sectors of the town suffered higher damage. One factor causing the uneven distribution of the effects is considered to be the presence of grottoes. <br><br> To strengthen this work hypothesis it was necessary to in-depth investigate the subsoil of Rionero in Vulture. Therefore, geophysical data were correlated and integrated with data obtained from field surveys and historical documentary sources. All these investigations allowed to obtain more insights about the influences of the man-made caves on seismic damage

    Measuring the Obscuring Column of a Disk Megamaser AGN in a Nearby Merger

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    Active galactic nuclei (AGNs) hosting disk water megamasers are well known to be obscured by large amounts of gas, likely due to the presence along the line of sight of an almost edge-on disky structure orbiting the supermassive black hole. Correcting for the high obscuration is crucial to infer parameters intrinsic to the source, like its luminosity. We present a broadband X-ray spectral analysis of a water megamaser AGN in an early merger (NGC 5765B), combining Chandra and NuSTAR data. NGC 5765B is highly Compton-thick and reflection-dominated, following the general trend among disk megamasers. Combining the exquisite black hole mass from masers with our X-ray spectroscopy, the Eddington ratio of the megamaser is estimated to be in the 2%–14% range, and its robustness is confirmed through SED fitting
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