1,043 research outputs found

    Mid to late Holocene environmental changes along the coast of western Sardinia (Mediterranean Sea)

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    Multiproxy analysis composed of biostratigraphy and pollen analysis allowed reconstructing the palaeoecological and palaeoenvironmental evolution of the Tirso river coastal plain in Sardinia (NW Mediterranean) in the last 6 millennia. We demonstrated that interplay between littoral and fluvial processes have significantly controlled the environmental evolution of the area and have played a key role in the pattern of historical and prehistorical settlements of this wide portion of western Sardinian coastline. At the end of Neolithic period (ca. 6.0 to 5.5 cal. ka BP) the area close to the shoreline was most likely characterized by large coastal lagoons intermittently connected to the open sea. Such saltwater influence is corroborated by faunal and pollen assemblages found in the landward portion of the Tirso coastal plain up to 2 km inland from the modern shoreline. Our data robustly document the end of the transgressive trend at ca. 5.5 cal. ka BP, and a dominant fluvial sedimentation since Final Neolithic period. At this time, a progradational trend started, causing the seaward migration of shoreline and, consequently, of the barrier-lagoon system. The major landscape modification tracked along the last 6 millennia may also explain the low density of historical and prehistorical remains in the Tirso coastal plain, especially if compared to the nearby rocky area of Sinis Peninsula densely inhabited since the Neolithic. Our data further provide new insights into the Relative Sea Level (RSL) evolution in this sector of the Mediterranean. In particular, we improved the mid-Holocene RSL record in Sardinia, where only scarce data were previously available

    Measurement of the effect of Non Ionising Energy Losses on the leakage current of Silicon Drift Detector prototypes for the LOFT satellite

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    The silicon drift detectors are at the basis of the instrumentation aboard the Large Observatory For x-ray Timing (LOFT) satellite mission, which underwent a three year assessment phase within the "Cosmic Vision 2015 - 2025" long-term science plan of the European Space Agency. Silicon detectors are especially sensitive to the displacement damage, produced by the non ionising energy losses of charged and neutral particles, leading to an increase of the device leakage current and thus worsening the spectral resolution. During the LOFT assessment phase, we irradiated two silicon drift detectors with a proton beam at the Proton Irradiation Facility in the accelerator of the Paul Scherrer Institute and we measured the increase in leakage current. In this paper we report the results of the irradiation and we discuss the impact of the radiation damage on the LOFT scientific performance.Comment: 21 pages, 7 figures, 2 tables. Accepted for publication by Journal of Instrumentation (JINST

    GAME: Grb and All-sky Monitor Experiment

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    We describe the GRB and All-sky Monitor Experiment (GAME) mission submitted by a large international collaboration (Italy, Germany, Czech Repubblic, Slovenia, Brazil) in response to the 2012 ESA call for a small mission opportunity for a launch in 2017 and presently under further investigation for subsequent opportunities. The general scientific objective is to perform measurements of key importance for GRB science and to provide the wide astrophysical community of an advanced X-ray all-sky monitoring system. The proposed payload was based on silicon drift detectors (~1-50 keV), CdZnTe (CZT) detectors (~15-200 keV) and crystal scintillators in phoswich (NaI/CsI) configuration (~20 keV-20 MeV), three well established technologies, for a total weight of ~250 kg and a required power of ~240 W. Such instrumentation allows a unique, unprecedented and very powerful combination of large field of view (3-4 sr), a broad energy energy band extending from ~1 keV up to ~20 MeV, an energy resolution as good as ~300 eV in the 1-30 keV energy range, a source location accuracy of ~1 arcmin. The mission profile included a launch (e.g., by Vega) into a low Earth orbit, a baseline sky scanning mode plus pointed observations of regions of particular interest, data transmission to ground via X-band (4.8 Gb/orbit, Alcantara and Malindi ground stations), and prompt transmission of GRB / transient triggers.Comment: 13 pages, 8 figures, published in International Journal of Modern Physics

    Effects of conventional and high-definition transcranial direct current stimulation (tDCS) on driving abilities: A tDCS-driving simulator study

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    Due to the multitasking nature of driving, drivers are physiologically distracted by both relevant and irrelevant environmental stimuli. The ability to select relevant stimuli and suppress irrelevant distractors during driving are two relevant factors for safety. There is a lot of evidence suggesting that the frontal eye field (FEF) plays an important role in target selection and distractors suppression, as well as in attentional mechanisms crucial for safety driving performance. Taking these two points into account, this study was designed to examine the effects of different transcranial direct current stimulation (tDCS) montages over right FEF to determine whether stimulation of FEF could improve attentional mechanisms in a simulated driving environment. Twenty-seven adult participants took part in the study. A specific driving simulator task was developed in which participants had to respond to brake light events of a preceding car in front of them while driving. The second distracting task consisted of road signs of countries and cities that appeared together with braking lights or alone. Participants were required to respond to one of the two categories with their right hand. These two tasks could be performed alone or in a combined condition. Each participant completed three sessions comparing the effects of different tDCS montages, i.e. conventional, focal 4*1 ring high-definition (HD-tDCS) and sham stimulations over the right FEF. Results indicated an overall better performance under the focal HD-tDCS condition. In particular, participants improved their performance both in braking light RTs and in the second distracting task. Taken together these results are interesting from a theoretical and methodological point of view, by demonstrating a direct effect of anodal focal HD-tDCS on FEF in attentional response during an ecological driving task

    Simulations of the X-ray imaging capabilities of the Silicon Drift Detectors (SDD) for the LOFT Wide Field Monitor

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    The Large Observatory For X-ray Timing (LOFT), selected by ESA as one of the four Cosmic Vision M3 candidate missions to undergo an assessment phase, will revolutionize the study of compact objects in our galaxy and of the brightest supermassive black holes in active galactic nuclei. The Large Area Detector (LAD), carrying an unprecedented effective area of 10 m^2, is complemented by a coded-mask Wide Field Monitor, in charge of monitoring a large fraction of the sky potentially accessible to the LAD, to provide the history and context for the sources observed by LAD and to trigger its observations on their most interesting and extreme states. In this paper we present detailed simulations of the imaging capabilities of the Silicon Drift Detectors developed for the LOFT Wide Field Monitor detection plane. The simulations explore a large parameter space for both the detector design and the environmental conditions, allowing us to optimize the detector characteristics and demonstrating the X-ray imaging performance of the large-area SDDs in the 2-50 keV energy band.Comment: Proceedings of SPIE, Vol. 8443, Paper No. 8443-210, 201

    Beam test results of the irradiated Silicon Drift Detector for ALICE

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    The Silicon Drift Detectors will equip two of the six cylindrical layers of high precision position sensitive detectors in the ITS of the ALICE experiment at LHC. In this paper we report the beam test results of a SDD irradiated with 1 GeV electrons. The aim of this test was to verify the radiation tolerance of the device under an electron fluence equivalent to twice particle fluence expected during 10 years of ALICE operation.Comment: 6 pages,6 figures, to appear in the proceedings of International Workshop In high Multiplicity Environments (TIME'05), 3-7 October 2005, Zurich,Switzerlan

    The World Atlas of Last Interglacial Shorelines (version 1.0)

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    This paper presents version 1.0 of the World Atlas of Last Interglacial Shorelines (WALIS), a global database of sea-level proxies and samples dated to marine isotope stage 5 (∼ 80 to 130 ka). The database includes a series of datasets compiled in the framework of a special issue published in this journal (https://essd.copernicus.org/articles/special_issue1055.html, last access: 15 December 2022). This paper collates the individual contributions (archived in a Zenodo community at https://zenodo.org/communities/walis_database/, last access: 15 December 2022) into an open-access, standalone database (Rovere et al., 2022, https://doi.org/10.5281/zenodo.7348242). The release of WALIS 1.0 includes complete documentation and scripts to download, analyze, and visualize the data (https://alerovere.github.io/WALIS/, last access: 15 December 2022). The database contains 4545 sea-level proxies (e.g., marine terraces or fossil beach deposits), 4110 dated samples (e.g., corals dated with U-series), and 280 other time constraints (e.g., biostratigraphic constraints or tephra layers) interconnected with several tables containing accessory data and metadata. By creating a centralized database of sea-level proxy data for the Last Interglacial, the WALIS database will be a valuable resource to the broader paleoclimate community to facilitate data–model integration and intercomparisons, assessments of sea-level reconstructions between different studies and different regions, as well as comparisons between past sea-level history and other paleoclimate proxy data.</p

    Interstitial pneumonia with autoimmune features: Why rheumatologist–pulmonologist collaboration is essential

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    In 2015 the European Respiratory Society (ERS) and the American Thoracic Society (ATS) “Task Force on Undifferentiated Forms of Connective Tissue Disease-associ-ated Interstitial Lung Disease” proposed classification criteria for a new research category defined as “Interstitial Pneumonia with Autoimmune Features” (IPAF), to uniformly de-fine patients with interstitial lung disease (ILD) and features of autoimmunity, without a definite connective tissue disease. These classification criteria were based on a variable combination of features obtained from three domains: a clinical domain consisting of extra-thoracic features, a serologic domain with specific autoantibodies, and a morphologic domain with imaging patterns, histopathological findings, or multicompartment in-volvement. Features suggesting a systemic vasculitis were excluded. Since publication of ERS/ATS IPAF research criteria, various retrospective studies have been published focusing on prevalence; clinical, morphological, and serological features; and prognosis of these patients showing a broad heterogeneity in the results. Recently, two prospective, cohort studies were performed, confirming the existence of some peculiarities for this clinical entity and the possible progression of IPAF to a defined connective tissue disease (CTD) in about 15% of cases. Moreover, a non-specific interstitial pneumonia pattern, an anti-nuclear antibody positivity, and a Raynaud phenomenon were the most common findings. In comparison with idiopathic pulmonary fibrosis (IPF), IPAF patients showed a better performance in pulmonary function tests and less necessity of oxygen delivery. However, at this stage of our knowledge, we believe that further prospective studies, possibly derived from multicenter cohorts and through randomized control trials, to further validate the proposed classification criteria are needed

    The X-Gamma Imaging Spectrometer (XGIS) onboard THESEUS

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    A compact and modular X and gamma-ray imaging spectrometer (XGIS) has been designed as one of the instruments foreseen on-board the THESEUS mission proposed in response to the ESA M5 call. The experiment envisages the use of CsI scintillator bars read out at both ends by single-cell 25 mm 2 Silicon Drift Detectors. Events absorbed in the Silicon layer (lower energy X rays) and events absorbed in the scintillator crystal (higher energy X rays and Gamma-rays) are discriminated using the on-board electronics. A coded mask provides imaging capabilities at low energies, thus allowing a compact and sensitive instrument in a wide energy band (~2 keV up to ~20 MeV). The instrument design, expected performance and the characterization performed on a series of laboratory prototypes are discussed.Comment: To be published in the Proceedings of the THESEUS Workshop 2017 (http://www.isdc.unige.ch/theseus/workshop2017.html), Journal of the Italian Astronomical Society (Mem.SAIt), Editors L. Amati, E. Bozzo, M. Della Valle, D. Gotz, P. O'Brien. Details on the THESEUS mission concept can be found in the white paper Amati et al. 2017 (arXiv:171004638) and Stratta et al. 2017 (arXiv:1712.08153
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