2,029 research outputs found

    Analisi del moto proprio di tre radio galassie: 3C 454.3, 3C 345, 3C 446

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    I nuclei galattici attivi sono delle galassie caratterizzate da una grande luminosità, rappre-sentano circa il 10% delle galassie osservabili. Il fenomeno che crea questa particolare ca-ratteristica si forma nel loro nucleo, zona centrale dalle dimensioni relativamente piccole rispetto all’intero ammasso di stelle. Inoltre, presentano emissione fortemente non termica su una larga banda dello spettro elettromagnetico. Alcune di queste regioni emettono getti di materia che possono essere molto lunghi, trasportando energia verso strutture estese (radiogalassie). La tesi tratta: la morfologia e classificazione degli AGN (Active Galactic Nuclei), le diver-se possibilità di osservare tali oggetti a seconda della banda che si vuole utilizzare ed un accenno al modello unificato. Si dedica un capitolo alla descrizione degli effetti relativistici che caratterizzano i nuclei attivi e dei meccanismi alla base dell’emissione non termica. La parte finale ù dedicata al lavoro sperimentale, in cui si prendono dati pubblici di diversi AGN e li si analizza attraverso software specifici di analisi dati, con lo scopo di delineare un moto proprio di tali oggetti cosmici e studiare la variabilità del loro flusso. In questa parte, oltre a presentare i nuclei attivi in esame descrivendo le loro caratteristiche e proprie-tà, si definisce il processo di analisi dati e la loro elaborazione. Nella conclusione vengono discussi i risultati dell’elaborazione con eventuali commenti e riflessioni sugli stessi

    Analisi del moto proprio di tre radio galassie: 3C 454.3, 3C 345, 3C 446

    Get PDF
    I nuclei galattici attivi sono delle galassie caratterizzate da una grande luminosità, rappre-sentano circa il 10% delle galassie osservabili. Il fenomeno che crea questa particolare ca-ratteristica si forma nel loro nucleo, zona centrale dalle dimensioni relativamente piccole rispetto all’intero ammasso di stelle. Inoltre, presentano emissione fortemente non termica su una larga banda dello spettro elettromagnetico. Alcune di queste regioni emettono getti di materia che possono essere molto lunghi, trasportando energia verso strutture estese (radiogalassie). La tesi tratta: la morfologia e classificazione degli AGN (Active Galactic Nuclei), le diver-se possibilità di osservare tali oggetti a seconda della banda che si vuole utilizzare ed un accenno al modello unificato. Si dedica un capitolo alla descrizione degli effetti relativistici che caratterizzano i nuclei attivi e dei meccanismi alla base dell’emissione non termica. La parte finale ù dedicata al lavoro sperimentale, in cui si prendono dati pubblici di diversi AGN e li si analizza attraverso software specifici di analisi dati, con lo scopo di delineare un moto proprio di tali oggetti cosmici e studiare la variabilità del loro flusso. In questa parte, oltre a presentare i nuclei attivi in esame descrivendo le loro caratteristiche e proprie-tà, si definisce il processo di analisi dati e la loro elaborazione. Nella conclusione vengono discussi i risultati dell’elaborazione con eventuali commenti e riflessioni sugli stessi

    Fabrication by magnetron sputtering and characterization of electrodes based on CuIn0.7Ga0.3Se2 (CIGS)

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    This thesis work aims to produce and test multilayer electrodes for their use as photocathode in a PEC device. The electrode developed is based on CIGS, a I-III-VI2 semiconductor material composed of copper (Cu), indium (In), Gallium (Ga) and selenium (Se). It has a bandgap in the range of 1.0-2.4 eV and an absorption coefficient of about 105cm−1, which makes it a promising photocathode for PEC water splitting. The idea of our multilayer electrode is to deposit a thin layer of CdS on top of CIGS to form a solid-state p–n junction and lead to more efficient charge separation. In addition another thin layer of AZO (Aluminum doped zinc oxide) is deposit on top of CdS since it would form a better alignment between the AZO/CdS/CIGS interfaces, which would help to drive the charge transport further and minimize charge recombination. Finally, a TiO2 layer on top of the electrodes is used as protective layer during the H2 evolution. FTO (Fluorine doped tin oxide) and Molybdenum are used as back-contact. We used the technique of RF magnetron sputtering to deposit the thin layers of material. The structural characterization performed by XDR measurement confirm a polycrystalline chalcopyrite structural with a preferential orientation along the (112) direction for the CIGS. From linear fit of the Tauc plot, we get an energy gap of about 1.16 eV. In addition, from a four points measurements, we get a resistivity of 0.26 Ωcm. We performed an electrochemical characterization in cell of our electrodes. The results show that our samples have a good stability but produce a photocurrent of the order of ÎŒA, three orders of magnitude smaller than our targets. The EIS analysis confirm a significant depletion of the species in front of the electrode causing a lower conversion of the species and less current flows

    Events with Isolated Charged Leptons and Large Missing Transverse Momentum at HERA

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    Striking events with isolated charged leptons, large missing transverse momentum and large transverse momentum of the hadronic final state were observed at the electron proton collider HERA in a data sample corresponding to a luminosity of about 130 pb-1. The H1 collaboration observed 11 events with isolated electrons or muons and with transverse momentum above 25 GeV. Only 3.4+-0.6 events were expected from Standard Model (SM) processes. Six of these events have a transverse momentum of greater than 40 GeV, while 1.3+-0.3 events were expected. The ZEUS collaboration observed good agreement with the SM. However, ZEUS found two events with a similar event topology, but tau leptons instead of electrons or muons in the final state. Only 0.2+-0.05 events were expected from SM processes. For various hypotheses the compatibility of the experimental results was investigated with respect to the SM and with respect to possible explanations beyond the SM. Prospects for the high-luminosity HERA-II data taking period are given

    Simulating the development and progression of Chronic Kidney Disease and osteoporosis in people living with HIV

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    The "chronicization" of HIV infection brings about a growing necessity to attentively evaluate current and potential complications when prescribing the individual therapeutic regimen. Starting from this need, we developed two HIV-comorbidity simulators that, basing on the evidence available in medical literature and starting from the current clinical and demographic features of the individual patient, project and compare the risks of developing and worsening of nephropathy and osteopathy associated with possible ARV regimens. These simulators are embedded in a desktop, user-friendly software thought to be used by the treating physician during prescription discussion with his/her patients, in order to highlight expected clinical outcomes and healthcare resource consumption that may differ according to the therapeutic strategy selected. In this article we present the sources and methods used in developing the mathematical models, alongside a set of examples and the results of cohort-level validation runs

    Prognostic value of reduced heart rate reserve during exercise in hypertrophic cardiomyopathy

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    Background: Sympathetic dysfunction can be evaluated by heart rate reserve (HRR) with exercise test. Objectives: To determine the value of HRR in predicting outcome of patients with hypertrophic cardiomyopathy (HCM). Methods: We enrolled 917 HCM patients (age = 49 +/- 15 years, 516 men) assessed with exercise stress echocardiography (ESE) in 11 centres. ESE modality was semi-supine bicycle in 51 patients (6%), upright bicycle in 476 (52%), and treadmill in 390 (42%). During ESE, we assessed left ventricular outflow tract obstruction (LVOTO), stress-induced new regional wall motion abnormalities (RWMA), and HRR (peak/rest heart rate, HR). By selection, all patients completed the follow-up. Mortality was the predetermined outcome measure Results: During ESE, RWMA occurred in 22 patients (2.4%) and LVOTO (>= 50 mmHg) in 281 (30.4%). HRR was 1.90 +/- 0.40 (lowest quartile 2.13). Higher resting heart rate (odds ratio 1.027, 95% CI: 1.018-1.036, p < 0.001), older age (odds ratio 1.021, 95% CI: 1.009-1.033, p < 0.001), lower exercise tolerance (mets, odds ratio 0.761, 95% CI: 0.708-0.817, p < 0.001) and resting LVOTO (odds ratio 1.504, 95% CI: 1.043-2.170, p = 0.029) predicted a reduced HRR. During a median follow-up of 89 months (interquartile range: 36-145 months), 90 all-cause deaths occurred. At multivariable analysis, lowest quartile HRR (Hazard ratio 2.354, 95% CI 1.116-4.968 p = 0.025) and RWMA (Hazard ratio 3.279, 95% CI 1.441-7.461 p = 0.004) independently predicted death, in addition to age (Hazard ratio 1.064, 95% CI 1.043-1.085 p < 0.001) and maximal wall thickness (Hazard ratio 1.081, 95% CI 1.037-1.128, p < 0.001). Conclusions: A blunted HRR during ESE predicts survival independently of RWMA in HCM patients.info:eu-repo/semantics/publishedVersio

    Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

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    This paper presents measurements of the W+→Ό+ÎœW^+ \rightarrow \mu^+\nu and W−→Ό−ΜW^- \rightarrow \mu^-\nu cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

    Standalone vertex ïŹnding in the ATLAS muon spectrometer

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    A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at √s = 7 TeV collected with the ATLAS detector at the LHC during 2011

    Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC

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    Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H →γ Îł, H → Z Z∗ →4l and H →W W∗ →lÎœlÎœ. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV, corresponding to an integrated luminosity of about 25 fb−1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined ïŹts probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson
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