Observation of inverse Compton emission from a long γ-ray burst.

Long-duration γ-ray bursts (GRBs) originate from ultra-relativistic jets launched from the collapsing cores of dying massive stars. They are characterized by an initial phase of bright and highly variable radiation in the kiloelectronvolt-to-megaelectronvolt band, which is probably produced within the jet and lasts from milliseconds to minutes, known as the prompt emission1,2. Subsequently, the interaction of the jet with the surrounding medium generates shock waves that are responsible for the afterglow emission, which lasts from days to months and occurs over a broad energy range from the radio to the gigaelectronvolt bands1-6. The afterglow emission is generally well explained as synchrotron radiation emitted by electrons accelerated by the external shock7-9. Recently, intense long-lasting emission between 0.2 and 1 teraelectronvolts was observed from GRB 190114C10,11. Here we report multi-frequency observations of GRB 190114C, and study the evolution in time of the GRB emission across 17 orders of magnitude in energy, from 5 × 10-6 to 1012 electronvolts. We find that the broadband spectral energy distribution is double-peaked, with the teraelectronvolt emission constituting a distinct spectral component with power comparable to the synchrotron component. This component is associated with the afterglow and is satisfactorily explained by inverse Compton up-scattering of synchrotron photons by high-energy electrons. We find that the conditions required to account for the observed teraelectronvolt component are typical for GRBs, supporting the possibility that inverse Compton emission is commonly produced in GRBs.

Enhanced detection of terrestrial gamma-ray flashes by AGILE.

At the end of March 2015 the onboard software configuration of the Astrorivelatore Gamma a Immagini Leggero (AGILE) satellite was modified in order to disable the veto signal of the anticoincidence shield for the minicalorimeter instrument. The motivation for such a change was the understanding that the dead time induced by the anticoincidence prevented the detection of a large fraction of Terrestrial Gamma-Ray Flashes (TGFs). The configuration change was highly successful resulting in an increase of one order of magnitude in TGF detection rate. As expected, the largest fraction of the new events has short duration (<100 µs), and part of them has simultaneous association with lightning sferics detected by the World Wide Lightning Location Network. The new configuration provides the largest TGF detection rate surface density (TGFs/km2/yr) to date, opening prospects for improved correlation studies with lightning and atmospheric parameters on short spatial and temporal scales along the equatorial region.

Discovery of powerful gamma-ray flares from the Crab Nebula.

The well-known Crab Nebula is at the center of the SN1054 supernova remnant. It consists of a rotationally powered pulsar interacting with a surrounding nebula through a relativistic particle wind. The emissions originating from the pulsar and nebula have been considered to be essentially stable. Here, we report the detection of strong gamma-ray (100 mega-electron volts to 10 giga-electron volts) flares observed by the AGILE satellite in September 2010 and October 2007. In both cases, the total gamma-ray flux increased by a factor of three compared with the non-flaring flux. The flare luminosity and short time scale favor an origin near the pulsar, and we discuss Chandra Observatory x-ray and Hubble Space Telescope optical follow-up observations of the nebula. Our observations challenge standard models of nebular emission and require power-law acceleration by shock-driven plasma wave turbulence within an approximately 1-day time scale.

Terrestrial gamma-ray flashes as powerful particle accelerators.

Strong electric discharges associated with thunderstorms can produce terrestrial gamma-ray flashes (TGFs), i.e., intense bursts of x rays and γ rays lasting a few milliseconds or less. We present in this Letter new TGF timing and spectral data based on the observations of the Italian Space Agency AGILE satellite. We determine that the TGF emission above 10 MeV has a significant power-law spectral component reaching energies up to 100 MeV. These results challenge TGF theoretical models based on runaway electron acceleration. The TGF discharge electric field accelerates particles over the large distances for which maximal voltages of hundreds of megavolts can be established. The combination of huge potentials and large electric fields in TGFs can efficiently accelerate particles in large numbers, and we reconsider here the photon spectrum and the neutron production by photonuclear reactions in the atmosphere.

Gamma-ray localization of terrestrial gamma-ray flashes.

Terrestrial gamma-ray flashes (TGFs) are very short bursts of high-energy photons and electrons originating in Earth's atmosphere. We present here a localization study of TGFs carried out at gamma-ray energies above 20 MeV based on an innovative event selection method. We use the AGILE satellite Silicon Tracker data that for the first time have been correlated with TGFs detected by the AGILE Mini-Calorimeter. We detect 8 TGFs with gamma-ray photons of energies above 20 MeV localized by the AGILE gamma-ray imager with an accuracy of ∼5-10° at 50 MeV. Remarkably, all TGF-associated gamma rays are compatible with a terrestrial production site closer to the subsatellite point than 400 km. Considering that our gamma rays reach the AGILE satellite at 540 km altitude with limited scattering or attenuation, our measurements provide the first precise direct localization of TGFs from space.

Detection of gamma-ray emission from the Vela pulsar wind nebula with AGILE.

Pulsars are known to power winds of relativistic particles that can produce bright nebulae by interacting with the surrounding medium. These pulsar wind nebulae are observed by their radio, optical, and x-ray emissions, and in some cases also at TeV (teraelectron volt) energies, but the lack of information in the gamma-ray band precludes drawing a comprehensive multiwavelength picture of their phenomenology and emission mechanisms. Using data from the AGILE satellite, we detected the Vela pulsar wind nebula in the energy range from 100 MeV to 3 GeV. This result constrains the particle population responsible for the GeV emission and establishes a class of gamma-ray emitters that could account for a fraction of the unidentified galactic gamma-ray sources.

Extreme particle acceleration in the microquasar Cygnus X-3.

Super-massive black holes in active galaxies can accelerate particles to relativistic energies, producing jets with associated gamma-ray emission. Galactic 'microquasars', which are binary systems consisting of a neutron star or stellar-mass black hole accreting gas from a companion star, also produce relativistic jets, generally together with radio flares. Apart from an isolated event detected in Cygnus X-1, there has hitherto been no systematic evidence for the acceleration of particles to gigaelectronvolt or higher energies in a microquasar, with the consequence that we are as yet unsure about the mechanism of jet energization. Here we report four gamma-ray flares with energies above 100 MeV from the microquasar Cygnus X-3 (an exceptional X-ray binary that sporadically produces radio jets). There is a clear pattern of temporal correlations between the gamma-ray flares and transitional spectral states of the radio-frequency and X-ray emission. Particle acceleration occurred a few days before radio-jet ejections for two of the four flares, meaning that the process of jet formation implies the production of very energetic particles. In Cygnus X-3, particle energies during the flares can be thousands of times higher than during quiescent states.

[Alcohol and work: ethical-deontological and medico-legal remark upon the recent set of rules]. / Alcol e lavoro: commento etico-deontologico e medico-giuridico della recente normativa.

BACKGROUND AND OBJECTIVES: The Disposition of the Permanent Conference for the relation among the State, the Regions and the Autonomous Provinces of Trento and Bolzano, published in Gazzetta Ufficiale n. 75 on the 30th March 2006 the list of high-risk occupations under the influence of alcohol, activating de facto a previous law (Legge n. 125, 3017 march 2001, "Legge quadro in materia di alcol e di problemi alcolcorrelati"). We here present some ethical-deontological and medical-juridical profiles on the contents of this law and some consideration about its application. RESULTS AND CONCLUSIONS: Particular attention is dedicated to deontological aspects about industrial safety rules and to medico-legal aspects about occupation under the influence of alcohol, with references to complex relations among worker's discretion right, employer's right to the protection of his own interests and qualified doctor's (or someone to him comparable) right to the respect for the deontological code, with regard to benefit recipient information before the medical treatment. Authors'purpose is to evidence critical points and interpretative ambiguities of a regulation lacking in its practical applications, to provide further proposals of consideration, available to revalue a thematic rich in questions and with a significant social impact.

[Evaluation of the occupational risk related to exposure to electromagnetic fields according to the EC Directive 2004/40 EC: exposure during pregnancy]. / La valutazione del rischio da campi elettromagnetici al sensi della Direttiva Comunitaria 2004/40 CE: esposizione professionale in corso di gravidanza.

The EU Directive 2004/40/EC on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (electromagnetic fields) will introduce the need of an evaluation of the risk related to EMF occupational exposure in pregnancy. Nevertheless, data from research in this field are scarcely conclusive to date. Furthermore knowledge on this risk seems insufficient among OH physicians in Italy. Accordingly, there is an urgent need for further research, and for a diffusion of knowledge among OH physicians on possible risk to pregnancy due to occupational exposure to EMF.

Ureteral occlusion prosthesis.

Although temporary or definitive complete ureteral occlusion is rarely needed, there is a considerable number of reports introducing different devices to achieve this goal, most of which can be inserted with minimally invasive procedures. Easy placement is considered of paramount importance, as the candidates are very often in bad general condition as a result of previous surgery, radiotherapy, or other palliative treatments for cancer. A device that can be inserted and removed percutaneously is presented herein. It can be employed in cases of ureteral fistulas resulting from radiotherapy and ureterosigmoidostomy with good results. The technique is simple and not time consuming.

Plant extracts in BPH.

In Italy plant extracts represent 8.6% of all pharmacological prescriptions for Benign Prostatic Hyperplasia (data from 1991). This review evaluates all the suggested mechanisms of action for plant extracts. Recently we demonstrated an antiestrogenic effect of Serenoa Repens in BPH patients. Clinical trials with plant extracts have yielded conflicting results. In a recent review by Dreikorn and Richter, only five placebo controlled studies were found. Moreover, as opposed to chemically defined drugs, it is possible that for these extracts the active ingredients are not known; consequently pharmacodynamic and pharmacokinetic data are often missing. The International Consultation of Benign Prostatic Hyperplasia (Paris, June 1991) concluded that, to date, phytotherapeutic agents must be considered as a symptomatic treatment. Now more adequate pharmacological and clinical studies, placebo controlled, should determine the exact role of these drugs in the treatment of BPH.

[The professional responsibility of the factory physician]. / La responsabilità professionale del medico di fabbrica.

The author briefly reviews the present trends in jurisprudence concerning the professional liability of the physician in penal and civil law and, in the light of the much discussed decree issued by the Court of Cassation (Court of Appeal) (Decree No. 2799/86 - Labour Section), discusses the juridical position of the factory doctor, the juridical relationship between the doctor and the workforce, his contractual obligations, his rôle and his duties. The aspects that are more specifically appropriate to assessment of the professional liability of the factory doctor are described, commenting on the various criteria that may justify, in matters other than industrial accidents, recognition of the existence of an occupational disease.