2,327 research outputs found

    The deepest X-ray look at the Universe

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    The origin of the X-ray background, in particular at hard (2-10 keV) energies, has been a debated issue for more than 30 years. The Chandra deep fields provide the deepest look at the X-ray sky and are the best dataset to study the X-ray background. We searched the Chandra Deep Field South for X-ray sources with the aid of a dedicated wavelet-based algorithm. We are able to reconstruct the Log N-Log S source distribution in the soft (0.5-2 keV) and hard (2-10 keV) bands down to limiting fluxes of 2x10^{-17} erg s^{-1} cm^{-2} and 2x10^{-16} erg s^{-1} cm^{-2}, respectively. These are a factor ~5 deeper than previous investigations. We find that the soft relation continues along the extrapolation from higher fluxes, almost completely accounting for the soft X-ray background. On the contrary, the hard distribution shows a flattening below ~2x10^{-14} erg s^{-1} cm^{-2}. Nevertheless, we can account for >68% of the hard X-ray background, with the main uncertainty being the sky flux itself.Comment: Accepted for publication on ApJL. Two figures, requires emulateapj5 (included

    Testing the gamma-ray burst variability/peak luminosity correlation on a Swift homogeneous sample

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    We test the gamma-ray burst correlation between temporal variability and peak luminosity of the γ\gamma-ray profile on a homogeneous sample of 36 Swift/BAT GRBs with firm redshift determination. This is the first time that this correlation can be tested on a homogeneous data sample. The correlation is confirmed, as long as the 6 GRBs with low luminosity (<5x10^{50} erg s^{-1} in the rest-frame 100-1000 keV energy band) are ignored. We confirm that the considerable scatter of the correlation already known is not due to the combination of data from different instruments with different energy bands, but it is intrinsic to the correlation itself. Thanks to the unprecedented sensitivity of Swift/BAT, the variability/peak luminosity correlation is tested on low-luminosity GRBs. Our results show that these GRBs are definite outliers.Comment: Accepted for Publication in MNRAS. 10 pages, 5 figures, 3 table

    A cross-sectional study on prevalence and predictors of burnout among a sample of pharmacists employed in pharmacies in Central Italy

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    Burnout is defined as an occupational phenomenon linked to chronic workplace stress that has not been successfully managed and included among the factors influencing health status or contact with health services. Although several studies were performed for assessing this phenomenon, there is a lack of data on the prevalence of burnout and associated predictors, due to different definitions of the syndrome and heterogeneity of assessment methods. One of the well-known evidences on burnout is related to the highest risk professions, which include policemen, firemen, teachers, psychologists, medical students, nurses, physicians, and other health professionals, such as pharmacists. Objective. The aims of the present study were to (1) assess the occurrence of burnout syndrome among a sample of pharmacists employed in public and private pharmacies located in Rome province (Latium Region; central Italy); (2) evaluate the role of some potential predictors for the development of the syndrome. Materials and Methods. A questionnaire elaborated ad hoc was administered online to 2,000 members of the Association of Professional Pharmacists of Rome and its province and employed in public or private pharmacies. The questionnaire included the 14-item Shirom-Melamed Burnout Measure (SMBM) tool and questions on demographic characteristics and working conditions. Results. Physical exhaustion was the burnout dimension with the highest score; besides, approximately 11% of the studied pharmacists were categorized as having clinically relevant burnout levels (≥4.40). Several of the investigated variables significantly influenced the single burnout dimensions at the univariate analyses; multivariate analyses demonstrated that alcohol consumption and workplace location have a significant independent role on the overall SMBM index, while working time significantly influences clinically relevant burnout level. Conclusions. The results revealed that pharmacists are at risk of burnout, and thus, it is necessary to perform specific preventive intervention for managing this occupational threat

    A NEW INDOOR LIDAR-BASED MMS CHALLENGING COMPLEX ARCHITECTURAL ENVIRONMENTS

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    Abstract. The use of moving devices equipped with range- and image-based sensor, generically defined Mobile Mapping systems (MMS), have been quite a disruptive innovation in the development of Geomatics techniques for 3D surveying large indoor-outdoor spaces and offer multiple solutions. The recent expansion of portable devices in the form of trolleys, backpacks, handheld tools largely implements SLAM (Simultaneous Localization and Mapping) algorithms and technology based on both Lidar and/or visual solutions for answering to the positioning and the 3D reconstruction problems. The research on MMS is directed to improve both multi-sensor integration implementation and usability of systems in diversified use contexts and application fields. The aim of the presented research is the evaluation of the potential of the Swift system recently developed by FARO Technologies, that has been fine-tuned for regular and large extent interiors mapping (such as factories, hospitals, airports, offices). The work tries to preliminary investigate the data delivery and usability of the integrated system. This is based on three elements mounted on a sliding trolley moved by the operator walking: the ScanPlan profilometer working for the 2D SLAM mapping, the static TLS Focus S-series, and the smartphone managing the sensors operation and the acquisition progress. The evaluation strategy undertaken will be based on the global and local performance analysis related to the trajectory, the data accuracy, the metric content and consistency. Two test studies belonging to the 20th century. architecture are presented in a preliminary framework of evaluation and validation: a Liberty-style cinema and the Torino Esposizioni Hall B designed in ferrocement by pier Luigi Nervi

    Vapor phase Beckmann rearrangement using high silica zeolite catalyst

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    Vapor phase Beckmann rearrangement of cyclohexanone oxime to e-caprolactam has been studied using high silica zeolite catalysts. Catalysts with different crystal sizes and gel-ageing times have been activated by ionic exchange in different conditions by means of a highly basic solution and a nearly neutral solution both containing ammonium salts. Samples have been calcined at different temperatures in order modify the number of defective sites. We observed that samples exchanged by means of a highly basic solution (pH > 10)1,2 and calcined at a relatively lower temperature (450 C) show the most interesting catalytic results. X-ray powder diffraction patterns of these samples show2 retention of the unit cell symmetry (orthorhombic cell) if compared to the dried sample. NH3-TPD confirms the low acidity of high silica zeolites, however a higher amount of desorbed ammonia is observed for the samples exchanged at higher pH and calcined at 450 C. Due to silanol nests the IR spectra of the same samples show the formation of Si\u2013NH2 bonds which are absent in the same material exchanged by other methods. Such sites seem to promote the high stability of the high silica zeolite catalysts also to the regeneration which is needed to remove the heavy carbonaceous compounds from the catalyst surface

    1SXPS: A deep Swift X-ray Telescope point source catalog with light curves and spectra

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    We present the 1SXPS (Swift-XRT Point Source) catalog of 151,524 X-ray point-sources detected by the Swift-XRT in 8 years of operation. The catalog covers 1905 square degrees distributed approximately uniformly on the sky. We analyze the data in two ways. First we consider all observations individually, for which we have a typical sensitivity of ~3e-13 erg/cm2/s (0.3--10 keV). Then we co-add all data covering the same location on the sky: these images have a typical sensitivity of ~9e-14 erg/cm2/s (0.3--10 keV). Our sky coverage is nearly 2.5 times that of 3XMM-DR4, although the catalog is a factor of ~1.5 less sensitive. The median position error is 5.5" (90% confidence), including systematics. Our source detection method improves on that used in previous XRT catalogs and we report >68,000 new X-ray sources. The goals and observing strategy of the Swift satellite allow us to probe source variability on multiple timescales, and we find ~30,000 variable objects in our catalog. For every source we give positions, fluxes, time series (in four energy bands and two hardness ratios), estimates of the spectral properties, spectra and spectral fits for the brightest sources, and variability probabilities in multiple energy bands and timescales.Comment: 27 pages, 19 figures; accepted for publication in ApJS. The accompanying website, http://www.swift.ac.uk/1SXPS is live; the Vizier entry should be available shortl

    Bioprocessing of barley and lentil grains to obtain in situ synthesis of exopolysaccharides and composite wheat bread with improved texture and health properties

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    A comprehensive study into the potential of bioprocessing techniques (sprouting and sourdough fermentation) for improving the technological and nutritional properties of wheat breads produced using barley and lentil grains was undertaken. Dextran biosynthesis in situ during fermentation of native or sprouted barley flour (B or SB) alone or by mixing SB flour with native or sprouted lentil flour (SB-L or SB-SL) by Weissella paramesenteroides SLA5, Weissella confusa SLA4, Leuconostoc pseudomesenteroides DSM 20193 or Weissella confusa DSM 20194 was assessed. The acidi-fication and the viscosity increase during 24 h of fermentation with and without 16% sucrose (on flour weight), to promote the dextran synthesis, were followed. After the selection of the fermentation parameters, the bioprocessing was carried out by using Leuconostoc pseudomesenteroides DSM 20193 (the best LAB dextran producer, up to 2.7% of flour weight) and a mixture of SB-SL (30:70% w/w) grains, enabling also the decrease in the raffinose family oligosaccharides. Then, the SB-SL sourdoughs containing dextran or control were mixed with the wheat flour (30% of the final dough) and leavened with baker’s yeast before baking. The use of dextran-containing sourdough allowed the production of bread with structural improvements, compared to the control sourdough bread. Compared to a baker’s yeast bread, it also markedly reduced the predicted glycemic index, in-creased the soluble (1.26% of dry matter) and total fibers (3.76% of dry matter) content, giving pe-culiar and appreciable sensory attributes

    NuSTAR and multifrequency study of the two high-redshift blazars S5 0836+710 and PKS 2149-306

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    The most powerful blazars are the flat spectrum radio quasars whose emission is dominated by a Compton component peaking between a few hundred keV and a few hundred MeV. We selected two bright blazars, PKS 2149-306 at redshift z=2.345 and S5 0836+710 at z=2.172, in order to observe them in the hard X-ray band with the NuSTAR satellite. In this band the Compton component is rapidly rising almost up to the peak of the emission. Simultaneous soft-X-rays and UV-optical observations were performed with the Swift satellite, while near-infrared (NIR) data were obtained with the REM telescope. To study their variability, we repeated these observations for both sources on a timescale of a few months. While no fast variability was detected during a single observation, both sources were found to be variable in the X-ray band, up to 50%, between the two observations, with larger variability at higher energies. No variability was detected in the optical/NIR band. These data together with Fermi-LAT, WISE and other literature data are then used to study the overall spectral energy distributions (SEDs) of these blazars. Although the jet non-thermal emission dominates the SED, it leaves the UV band unhidden, allowing us to detect the thermal emission of the disc and to estimate the mass of the black hole. The non-thermal emission is well reproduced by a one-zone leptonic model. The non-thermal radiative processes are synchrotron, self-Compton and external Compton using seed photons from both the broad-line region (BLR) and the torus. We find that our data are better reproduced if we assume that the location of the dissipation region of the jet, R_diss, is in-between the torus, (at R_torus), and the BLR (R_torus>R_diss>R_BLR). The observed variability is explained by changing a minimum number of model parameters by a very small amount.Comment: 11 pages, 5 figures, accepted for publication in Ap
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