1,405 research outputs found

    The Fermi blazars' divide based on the diagnostic of the SEDs peak frequencies

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    We have studied the quasi-simultaneous Spectral Energy Distributions (SED) of 48 LBAS blazars, detected within the three months of the LAT Bright AGN Sample (LBAS) data taking period, combining Fermi and Swift data with radio NIR-Optical and hard-X/gamma-ray data. Using these quasi-simultaneous SEDs, sampling both the low and the high energy peak of the blazars broad band emission, we were able to apply a diagnostic tool based on the estimate of the peak frequencies of the synchrotron (S) and Inverse Compton (IC) components. Our analysis shows a Fermi blazars' divide based on the peak frequencies of the SED. The robust result is that the Synchrotron Self Compton (SSC) region divides in two the plane were we plot the peak frequency of the synchrotron SED vs the typical Lorentz factor of the electrons most contributing to the synchrotron emission and to the inverse Compton process. Objects within or below this region, radiating likely via the SSC process, are high-frequency-peaked BL Lac object (HBL), or low/intermediate-frequency peaked BL Lac object (LBL/IBL). All of the IBLs/LBLs within or below the SSC region are not Compton dominated. The objects lying above the SSC region, radiating likely via the External radiation Compton (ERC) process, are Flat Spectrum Radio Quasars and IBLs/LBLs. All of the IBLs/LBLs in the ERC region show a significant Compton dominance.Comment: Contribution to the Workshop SciNeGHe 2009/Gamma-ray Physics in the LHC era (Assisi - Italy, Oct. 7-9 2009

    Analysis of the Spectral Energy Distributions of Fermi bright blazars

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    Blazars are a small fraction of all extragalactic sources but, unlike other objects, they are strong emitters across the entire electromagnetic spectrum. In this study we have conducted a detailed investigation of the broad-band spectral properties of the gamma-ray selected blazars of the Fermi-LAT Bright AGN Sample (LBAS). By combining the accurately estimated Fermi gamma-ray spectra with Swift, radio, NIR-Optical and hard-X/gamma-ray data, collected within three months of the LBAS data taking period, we were able to assemble high-quality and quasi-simultaneous Spectral Energy Distributions (SED) for 48 LBAS blazars.Comment: 6 pages, 8 figures, "2009 Fermi Symposium", "eConf Proceedings C091122

    Equivalence between local Fermi gas and shell models in inclusive muon capture from nuclei

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    Motivated by recent studies of inclusive neutrino nucleus processes and muon capture within a correlated local Fermi gas model (LFG), we discuss the relevance of nuclear finite size effects in these reactions at low energy, in particular for muon capture. To disentangle these effects from others coming from the reaction dynamics we employ here a simple uncorrelated shell model that embodies the typical finite size content of the problem. The integrated decay widths of muon atoms calculated with this shell model are then compared for several nuclei with those obtained within the uncorrelated LFG, using in both models exactly the same theoretical ingredients and parameters. We find that the two predictions are in quite good agreement, within 1--7%, when the shell model density and the correct energy balance is used as input in the LFG calculation. The present study indicates that, despite the low excitation energies involved in the reaction, integrated inclusive observables, like the total muon capture width, are quite independent of the fine details of the nuclear wave functions.Comment: 11 pages, 8 figures. Final version to be published in EPJ

    Gleam: the GLAST Large Area Telescope Simulation Framework

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    This paper presents the simulation of the GLAST high energy gamma-ray telescope. The simulation package, written in C++, is based on the Geant4 toolkit, and it is integrated into a general framework used to process events. A detailed simulation of the electronic signals inside Silicon detectors has been provided and it is used for the particle tracking, which is handled by a dedicated software. A unique repository for the geometrical description of the detector has been realized using the XML language and a C++ library to access this information has been designed and implemented.Comment: 10 pages, Late

    Simulating the High Energy Gamma-ray sky seen by the GLAST Large Area Telescope

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    This paper presents the simulation of the GLAST high energy gamma-ray telescope. The simulation package, written in C++, is based on the Geant4 toolkit, and it is integrated into a general framework used to process events. A detailed simulation of the electronic signals inside Silicon detectors has been provided and it is used for the particle tracking, which is handled by a dedicated software. A unique repository for the geometrical description of the detector has been realized using the XML language and a C++ library to access this information has been designed and implemented. A new event display based on the HepRep protocol was implemented. The full simulation was used to simulate a full week of GLAST high energy gamma-ray observations. This paper outlines the contribution developed by the Italian GLAST software group.Comment: 6 pages, 4 figures, to be published in the Proceedings of the 6th International Symposium ''Frontiers of Fundamental and Computational Physics'' (FFP6), Udine (Italy), Sep. 26-29, 200

    Outpatient parents' views on shared-decision-making at an Italian children's hospital

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    Information is lacking on what parents in southern European countries know and how they view clinical shared-decision-making (SDM) for their children. This survey assesses general parental views on SDM and patient-physician SDM relationships in an Italian paediatric outpatients' clinic. In a 3-month cross-sectional survey, we enrolled 458 consecutive native and foreign Italian-speaking parents bringing their children to our public hospital for various reasons. Parents completed an anonymous questionnaire exploring their general views on SDM, including what doctor-patient relationship predominates today, and what approach reassures them most. Multivariate logistic regression analysed outcome data from parental questionnaire answers. Results are reported as percentages, odds ratios (OR) and 95% confidence intervals (CI). Multivariate logistic regression showed that 440 parents (96.1%) appreciated SDM, 245 (53.5%) preferred SDM for choosing children's treatment, 126 (27.5%) answered that SDM is the predominant relationship today, and most parents 275 (60.0%) felt reassured by SDM. More native than foreign Italian-speaking parents preferred SDM (97.0 vs 89.7%, OR = 3.8; 95% CI = 1.4-10.8). Highly-educated parents preferred SDM for choosing their child's therapy (57.9 vs 34.1%, OR = 2.7; 95% CI = 1.6-4.4) and this approach reassured them (64.3 vs 41.2%, OR = 2.5; 95% CI = 1.6-4.1). In conclusion, parents bringing children to an Italian outpatient clinic, especially highly-educated parents, wish to be offered SDM and find it reassuring. These findings should encourage paediatricians working in a challenging multicultural environment to change their physician-centred approach and engage parents in tailored SDM strategies

    Jastrow-type calculations of one-nucleon removal reactions on open ss-dd shell nuclei

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    Single-particle overlap functions and spectroscopic factors are calculated on the basis of Jastrow-type one-body density matrices of open-shell nuclei constructed by using a factor cluster expansion. The calculations use the relationship between the overlap functions corresponding to bound states of the (A1)(A-1)-particle system and the one-body density matrix for the ground state of the AA-particle system. In this work we extend our previous analyses of reactions on closed-shell nuclei by using the resulting overlap functions for the description of the cross sections of (p,d)(p,d) reactions on the open ss-dd shell nuclei 24^{24}Mg, 28^{28}Si and 32^{32}S and of 32^{32}S(e,ep)(e,e^{\prime}p) reaction. The relative role of both shell structure and short-range correlations incorporated in the correlation approach on the spectroscopic factors and the reaction cross sections is pointed out.Comment: 11 pages, 5 figures, to be published in Phys. Rev.
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