2,069 research outputs found

    GRB970228 and the class of GRBs with an initial spikelike emission: do they follow the Amati relation?

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    On the basis of the recent understanding of GRB050315 and GRB060218, we return to GRB970228, the first Gamma-Ray Burst (GRB) with detected afterglow. We proposed it as the prototype for a new class of GRBs with "an occasional softer extended emission lasting tenths of seconds after an initial spikelike emission". Detailed theoretical computation of the GRB970228 light curves in selected energy bands for the prompt emission are presented and compared with observational BeppoSAX data. From our analysis we conclude that GRB970228 and likely the ones of the above mentioned new class of GRBs are "canonical GRBs" have only one peculiarity: they exploded in a galactic environment, possibly the halo, with a very low value of CBM density. Here we investigate how GRB970228 unveils another peculiarity of this class of GRBs: they do not fulfill the "Amati relation". We provide a theoretical explanation within the fireshell model for the apparent absence of such correlation for the GRBs belonging to this new class.Comment: 5 pages, 3 figures, in the Proceedings of the "4th Italian-Sino Workshop on Relativistic Astrophysics", held in Pescara, Italy, July 20-28, 2007, C.L. Bianco, S.-S. Xue, Editor

    Luminosity Function Statistics Applied in GRB Samples

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    The luminosity function (LF) statistics applied in data of GRBs detected by GBM/Fermi and BAT/Swift is the theme approached in this work. The LF is a strong statistical tool to extract useful information from astrophysical samples, and the key point of this statistical analysis is in the detector sensitivity, where we have performed careful analysis. We produced, by LF statistics, the GRB predicted distributions of: peak ux N(Fpk), redshift N(z) and peak luminosity N(Lpk). We also used different GRB rates. We performed a comparison between the distributions predicted and observed (with and without redshifts), where we had to build a list with more then 250 GRBs with known redshifts. We estimated the effects of the Malmquist bias in all samples, and we looked for a correlation between the isotropic luminosity and the Band peak spectral energy

    Emergence of a filamentary structure in the fireball from GRB spectra

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    It is shown that the concept of a fireball with a definite filamentary structure naturally emerges from the analysis of the spectra of Gamma-Ray Bursts (GRBs). These results, made possible by the recently obtained analytic expressions of the equitemporal surfaces in the GRB afterglow, depend crucially on the single parameter R describing the effective area of the fireball emitting the X- and gamma ray radiation. The X- and gamma ray components of the afterglow radiation are shown to have a thermal spectrum in the co-moving frame of the fireball and originate from a stable shock front described self-consistently by the Rankine-Hugoniot equations. Precise predictions are presented on a correlations between spectral changes and intensity variations in the prompt radiation verifiable, e.g., by the Swift and future missions. The highly variable optical and radio emission depends instead on the parameters of the surrounding medium. The GRB 991216 is used as a prototype for this model.Comment: 9 pages, 3 figures, to appear on International Journal of Modern Physics

    Post-graduate medical education in public health: The case of Italy and a call for action

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    Public health technical expertise is of crucial importance to inform decision makers\u2019 action in the field of health and its broader determinants. Improving education and training of public health professionals for both practice and research is the starting point to strengthen the role of public health so that current health challenges can be efficiently tackled. At the Association of Schools of Public Health in the European Region (ASPHER) Deans\u2019 & Directors\u2019 2017 Annual Retreat, we presented the structure and management of public health training system in Italy, and we reported recent data on Italian public health specialists\u2019 educational experience, employment opportunities and job satisfaction. Public health training in Italy is implemented in the context of the post-graduate medical education residency programme in Hygiene and Preventive Medicine, delivered by 34 University-based Schools of Public Health. We report relatively high employment rates across the county and wide spectrum of career opportunities for young public health specialists. However, job security is low and training expectations only partially met. We call upon other Schools of Public Health to scale up the survey within the broad ASPHER community in a shared and coordinated action of systematically collecting useful data that can inform the development of public health education and training models, their implementation and fruitful interaction with population health, health systems and services

    The Magnitude of Androgen Receptor Positivity in Breast Cancer Is Critical for Reliable Prediction of Disease Outcome

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    Purpose: Consensus is lacking regarding the androgen receptor (AR) as a prognostic marker in breast cancer. The objectives of this study were to comprehensively review the literature on AR prognostication and determine optimal criteria for AR as an independent predictor of breast cancer survival. Experimental Design: AR positivity was assessed by immunostaining in two clinically validated primary breast cancer cohorts [training cohort, n = 219; validation cohort, n = 418; 77% and 79% estrogen receptor alpha (ERα) positive, respectively]. The optimal AR cut-point was determined by ROC analysis in the training cohort and applied to both cohorts. Results: AR was an independent prognostic marker of breast cancer outcome in 22 of 46 (48%) previous studies that performed multivariate analyses. Most studies used cut-points of 1% or 10% nuclear positivity. Herein, neither 1% nor 10% cut-points were robustly prognostic. ROC analysis revealed that a higher AR cut-point (78% positivity) provided optimal sensitivity and specificity to predict breast cancer survival in the training (HR, 0.41; P = 0.015) and validation (HR, 0.50; P = 0.014) cohorts. Tenfold cross-validation confirmed the robustness of this AR cut-point. Patients with ERα-positive tumors and AR positivity ≄78% had the best survival in both cohorts (P 0.87) had the best outcomes (P < 0.0001). Conclusions: This study defines an optimal AR cut-point to reliably predict breast cancer survival. Testing this cut-point in prospective cohorts is warranted for implementation of AR as a prognostic factor in the clinical management of breast cancer

    What can we learn from GRBs?

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    We review our recent results on the classification of long and short gamma-ray bursts (GRBs) in different subclasses. We provide observational evidences for the binary nature of GRB progenitors. For long bursts the induced gravitational collapse (IGC) paradigm proposes as progenitor a tight binary system composed of a carbon-oxygen core (COcore) and a neutron star (NS) companion; the supernova (SN) explosion of the COcore triggers a hypercritical accretion process onto the companion NS. For short bursts a NS–NS merger is traditionally adopted as the progenitor. We also indicate additional sub-classes originating from different progenitors: (COcore)–black hole (BH), BH–NS, and white dwarf–NS binaries. We also show how the outcomes of the further evolution of some of these sub-classes may become the progenitor systems of other sub-classes

    U-PHOS Project: Development of a Large Diameter Pulsating Heat Pipe Experiment on board REXUS 22

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    U-PHOS Project aims to analyse and characterise the behaviour of a large diameter Pulsating Heat Pipe (PHP) on board REXUS 22 sounding rocket. A PHP is a passive thermal control device consisting of a serpentine capillary tube, evacuated, partially filled with a working fluid and finally sealed. In this configuration, the liquid and vapour phases are randomly distributed in the form of liquid slugs and vapour plugs. The heat is efficiently transported by means of the self-sustained oscillatory fluid motion driven by the phase change phenomena. On ground conditions, a small diameter is required in order to obtain a confined slug flow regime. In milli-gravity conditions, buoyancy forces become less intense and the PHP diameter may be increased still maintaining the slug/plug flow configuration typical of the PHP operation. Consequently, the PHP heat power capability may be increased too. U-PHOS aims at proving that a Large Diameter PHP effectively works in milli-g conditions by characterizing its thermal response during a sounding rocket flight. The actual PHP tube is made of aluminum (3 mm inner diameter, filled with FC-72), heated at the evaporator by a compact electrical resistance, cooled at the condenser by a Phase Change Material (PCM) embedded in a metallic foam. The tube wall temperatures are recorded by means of Fibre Bragg Grating (FBG) sensors; the local fluid pressure is acquired by means of a pressure transducer. The present work intends to report the actual status of the project, focusing in particular on the experiment improvements with respect to the previous campaign

    Determinants of weight, psychological status, food contemplation and lifestyle changes in patients with obesity during the COVID-19 lockdown: a nationwide survey using multiple correspondence analysis

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    Introduction The corona virus disease 2019 (COVID-19) pandemic forced most of the Italian population into lockdown from 11 March to 18 May 2020. A nationwide survey of Italian Clinical Nutrition and Dietetic Services (Obesity Centers or OCs) was carried out to assess the impact of lockdown restrictions on the physical and mental wellbeing of patients with obesity (PWO) who had follow-up appointments postponed due to lockdown restrictions and to compare determinants of weight gain before and after the pandemic. Methods We designed a structured 77-item questionnaire covering employment status, diet, physical activity and psychological aspects, that was disseminated through follow-up calls and online between 2 May and 25 June 2020. Data were analyzed by multiple correspondence analysis (MCA) and multiple linear regression. Results A total of 1,232 PWO from 26 OCs completed the questionnaires (72% female, mean age 50.2 +/- 14.2 years; mean BMI 34.7 +/- 7.6 kg/m(2); 41% obesity class II to III). During the lockdown, 48.8% gained, 27.1% lost, while the remainder (24.1%) maintained their weight. The mean weight change was +2.3 +/- 4.8 kg (in weight gainers: +4.0 +/- 2.4 kg; +4.2% +/- 5.4%). Approximately 37% of participants experienced increased emotional difficulties, mostly fear and dissatisfaction. Sixty-one percent reduced their physical activity (PA) and 55% experienced a change in sleep quality/quantity. The lack of online contact (37.5%) with the OC during lockdown strongly correlated with weight gain (p &lt; 0.001). Using MCA, two main clusters were identified: those with unchanged or even improved lifestyles during lockdown (Cluster 1) and those with worse lifestyles during the same time (Cluster 2). The latter includes unemployed people experiencing depression, boredom, dissatisfaction and increased food contemplation and weight gain. Within Cluster 2, homemakers reported gaining weight and experiencing anger due to home confinement. Conclusions Among Italian PWO, work status, emotional dysregulation, and lack of online communication with OCs were determinants of weight gain during the lockdown period

    Spatiotemporal distribution and speciation of silver nanoparticles in the healing wound

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    Funding: This research was supported by funds from the MIUR-FIRB project number RBFR08M6W8. Acknowledgments: ELGA LabWater is acknowledged for providing the PURELAB Option-Q and Ultra Analytic systems, which produced the ultra-pure water used for Ag determinations. Adam Douglas and Dhinesh Asogan are acknowledged for their technical support during LA-ICP-MS analysis at the University of Venice, and the authors gratefully acknowledge Bill Spence and Teledyne Cetac Technologies for the loan of the laser ablation instrumentation. Laura Molin and ISTM-CNR are acknowledged for MALDI-TOF-MS analysis. The synchrotron experiments were performed on beamline ID21 at the European Synchrotron Radiation Facility (ESRF), Grenoble, France (proposal #CH4121).Peer reviewedPostprin
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