887 research outputs found

    X-ray view of four high-luminosity Swift/BAT AGN: Unveiling obscuration and reflection with Suzaku

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    The Swift/BAT nine-month survey observed 153 AGN, all with ultra-hard X-ray BAT fluxes in excess of 10^-11 erg cm^-2 s^-1 and an average redshift of 0.03. Among them, four of the most luminous BAT AGN (44.73 < Log L(BAT) < 45.31) were selected as targets of Suzaku follow-up observations: J2246.0+3941 (3C 452), J0407.4+0339 (3C 105), J0318.7+6828, and J0918.5+0425. The column density, scattered/reflected emission, the properties of the Fe K line, and a possible variability are fully analyzed. For the latter, the spectral properties from Chandra, XMM-Newton and Swift/XRT public observations were compared with the present Suzaku analysis. Of our sample, 3C 452 is the only certain Compton-thick AGN candidate because of i) the high absorption and strong Compton reflection; ii) the lack of variability; iii) the "buried" nature, i.e. the low scattering fraction (<0.5%) and the extremely low relative [OIII] luminosity. In contrast 3C 105 is not reflection-dominated, despite the comparable column density, X-ray luminosity and radio morphology, but shows a strong long-term variability in flux and scattering fraction, consistent with the soft emission being scattered from a distant region (e.g., the narrow emission line region). The sample presents high (>100) X-to-[OIII] luminosity ratios, confirming the [OIII] luminosity to be affected by residual extinction in presence of mild absorption, especially for "buried" AGN such as 3C 452. Three of our targets are powerful FRII radio galaxies, making them the most luminous and absorbed AGN of the BAT Seyfert survey despite the inversely proportional N_H - L_X relation.Comment: A&A paper in press, 17 page

    Simbol-X Background Minimization: Mirror Spacecraft Passive Shielding Trade-Off Study

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    The present work shows a quantitative trade-off analysis of the Simbol-X Mirror Spacecraft (MSC) passive shielding, in the phase space of the various parameters: mass budget, dimension, geometry, and composition. A simplified physical (and geometrical) model of the sky screen, implemented by means of a GEANT4 simulation, has been developed to perform a performance-driven mass optimization and evaluate the residual background level on Simbol-X focal plane.Comment: 3 pages, 6 figures, to appear in the proceedings of the second Simbol-X International Symposium "Simbol-X - Focusing on the Hard X-ray Universe", AIP Conf. Proc. Series, P. Ferrando and J. Rodriguez ed

    Associating Metrics of Hunting Effort with Hunting Rate: A Case Study with the Wild Boar Sus scrofa

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    Wild boar Sus scrofa populations have increased dramatically in recent decades throughout Europe. While hunting is widely used in management activities; it rarely has an important role in regulating and reducing wild boar populations. Therefore, increasing the efficiency of hunting is a compelling issue. In this study, we used a three-year dataset (2016–2018) on a wild boar population living in Campania (southern Italy) as a case study to explore how the hunting effort made in collective drive hunts affected the hunting rate, estimated as the number of individuals culled per day. We fitted a Linear Mixed Model, in which we included the number of wild boars culled per drive hunt as the dependent variable, and the number of beaters, shooters and dogs and the month during which hunting occurred as the predictors. A mean of 1.81 wild boars were culled per drive hunt. The number of culled animals per hunt increased with the increasing number of hunting dogs and with the progression of the hunting season (i.e., from October to December), whereas the number of beaters and shooters had no effect. Overall, we observed a low hunting rate. We suggest that adjusting the hunting calendar and reorganising wild boar collective hunts, e.g., through an appropriate management of the number and training of hunting dogs, are essential to increase the hunting rate. Our results can be useful for wildlife managers to enhance hunting contribution in counteracting the negative impact of wild boar

    The “sant’angelo in criptis” cave church in santeramo in colle (Apulia, south italy): A multidisciplinary study for the evaluation of conservation state and stability assessment

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    Sant’Angelo in Criptis (Santeramo in Puglia, South Italy) is a karst cave located in the Alta Murgia National Park (aspiring geopark), presently degraded, but with signs of intense past visiting activity for worship, as testified by the beautiful wall paintings and the large number of inscriptions and engravings on the cave walls. With the aim to permit the desirable restoration and the following fruition of this ancient geo-cultural heritage, a multidisciplinary investigation of the cave was carried out in this study. The 3D cave model permitted a detailed map of the area and highlighted that the cave vault, although very regular, somewhere presents chimneys that develop upwards, indicating areas where the rock thickness is now very small. The stability analysis indicates that presently, the cave does not show remarkable signs of instability, but block failures, toppling and roof collapse are possible. Archaeometry investigations confirmed the past importance of this holy site, as testified by the overlapping in the paintings of three different pictorial cycles and the use of precious pigments, thus confirming the necessity of preservation through a conservation management strategy for a full future fruition of the cave

    GLOBAL STABILITY AND BIFURCATIONS ANALYSIS OF AN EPIDEMIC MODEL WITH CONSTANT REMOVAL RATE OF THE INFECTIVE

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    In this thesis we consider an epidemic model with a constant removal rate of infective individuals is proposed to understand the effect of limited resources for treatment of infective on the disease spread. It is found that it is unnecessary to take such a large treatment capacity that endemic equilibria disappear to eradicate the disease. It is shown that the outcome of disease spread may depend on the position of the initial states for certain range of parameters. It is also shown that the model undergoes a sequence of bifurcations including saddle-node bifurcation, subcritical Hopf bifurcation. Keyword: Epidemic model, nonlinear incidence rate, basic reproduction number, local and global stabilit

    Enhancement of the formation of ultracold 85^{85}Rb2_2 molecules due to resonant coupling

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    We have studied the effect of resonant electronic state coupling on the formation of ultracold ground-state 85^{85}Rb2_2. Ultracold Rb2_2 molecules are formed by photoassociation (PA) to a coupled pair of 0u+0_u^+ states, 0u+(P1/2)0_u^+(P_{1/2}) and 0u+(P3/2)0_u^+(P_{3/2}), in the region below the 5S+5P1/25S+5P_{1/2} limit. Subsequent radiative decay produces high vibrational levels of the ground state, X1Σg+X ^1\Sigma_g^+. The population distribution of these XX state vibrational levels is monitored by resonance-enhanced two-photon ionization through the 21Σu+2 ^1\Sigma_u^+ state. We find that the populations of vibrational levels vv''=112-116 are far larger than can be accounted for by the Franck-Condon factors for 0u+(P1/2)X1Σg+0_u^+(P_{1/2}) \to X ^1\Sigma_g^+ transitions with the 0u+(P1/2)0_u^+(P_{1/2}) state treated as a single channel. Further, the ground-state molecule population exhibits oscillatory behavior as the PA laser is tuned through a succession of 0u+0_u^+ state vibrational levels. Both of these effects are explained by a new calculation of transition amplitudes that includes the resonant character of the spin-orbit coupling of the two 0u+0_u^+ states. The resulting enhancement of more deeply bound ground-state molecule formation will be useful for future experiments on ultracold molecules.Comment: 6 pages, 5 figures; corrected author lis

    A Unique Amphibole- and Magnetite-Rich Carbonaceous Chondrite from Almahata Sitta

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    Almahata Sitta (AhS) 202 from the UoK collection represents a clast from the polymict breccia asteroid 2008 TC3. AhS 202 was recognized as a unique carbonaceous chondrite (CC) with a high magnetite content. Here we report that it also contains a significant amount of amphibole, a mineral that is very rare in chondrites and has not previously been reported in significant abundance in a CC. We present new petrographic, oxygen isotope, and micro-FTIR data. We discuss petrogenesis and possible relationships to known CC

    Buccal mucosa is a promising graft in Peyronie's disease surgery. Our experience and a brief literature review on autologous grafting materials

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    AIM: Peyronie's Disease (PD) is an under reported acquired benign condition that, at the moment, is not curable with medical therapy. Surgery represent the gold standard of treatment. Surgical approaches are several and they consist in "plication techniques" or plaque incision/excision with grafting of resulting albuginea defect. Among grafting procedures, albuginea defect substitution with autologous materials demonstrated over the years not inferior results respect to heterologous grafts. Buccal mucosa graft (BMG) is not usually emphasized in many review articles and clinical series are yet limited. METHODS: We present our experience with seventeen plaque incision procedures and BMG in surgical correction of complex penile curvatures due to PD performed in a period of 30 months. Our analyses was focused on buccal mucosa graft characteristics as major determinant of the surgical success. We also conducted a brief literature review on autologous grafting materials used in reconstructive penile surgery for PD. RESULTS: Our cosmetics and functional results consists in a 100% of functional penile straightening with no relapses and 5,8% of de novo erectile dysfunction. Mean age was 56.4 years, mean follow-up of 22.5 (6-36) months. No complications graft related were observed. Operative time was 115.3 minutes in mean. Over 94% of patients referred they were "really much better" and "much better" satisfied based on PGI-I questionnaire administrated at the last follow- up visit. CONCLUSION: BMG is revealing as an optimal choice for reconstructive surgery in PD. Anatomical characteristics consisting in the great elasticity, the quick integration time and the easy harvesting technique lead to high cosmetics and functional success rate, without omitting economical and invasiveness aspects

    On the Angular Resolution of the AGILE gamma-ray imaging detector

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    We present a study of the Angular Resolution of the AGILE gamma-ray imaging detector (GRID) that is operational in space since April 2007. The AGILE instrument is made of an array of 12 planes each equipped with a Tungsten converter and Silicon micros trip detectors and is sensitive in the energy range 50 MeV - 10 GeV. Among the space instruments devoted to gamma-ray astrophysics, AGILE uniquely exploits an analog readout system with dedicated electronics coupled with Silicon detectors. We show the results of Monte Carlo simulations carried out to reproduce the gamma-ray detection by the GRID, and we compare them to in-flight data. We use the Crab (pulsar + Nebula) system for discussion of real data performance, since its E^{-2} energy spectrum is representative of the majority of gamma-ray sources. For Crab-like spectrum sources, the GRID angular resolution (FWHM of ~4deg at 100 MeV; ~0.8deg at 1 GeV; ~0.9deg integrating the full energy band from 100 MeV to tens of GeV) is stable across a large field of view, being characterized by a flat response up to 30deg off-axis. A comparison of the angular resolution obtained by the two operational gamma-ray instruments, AGILE-GRID and Fermi-LAT, is interesting in view of future gamma-ray missions, that are currently under study. The two instruments exploit different detector configurations affecting the angular resolution: the former being optimized in the readout and track reconstruction especially in the low-energy band, the latter in terms of converter thickness and power consumption. We show that, despite these differences, the angular resolution of both instruments is very similar between 100 MeV and a few GeV.Comment: 19 pages, 8 figures, accepted for publication in Ap
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