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.

The discovery and measurements of a Higgs boson.

In July 2012, the ATLAS and CMS collaborations at CERN's Large Hadron Collider announced the discovery of a Higgs-like boson, a new heavy particle at a mass more than 130 times the mass of a proton. Since then, further data have revealed its properties to be strikingly similar to those of the Standard Model Higgs boson, a particle expected from the mechanism introduced almost 50 years ago by six theoreticians including British physicists Peter Higgs from Edinburgh University and Tom Kibble from Imperial College London. The discovery is the culmination of a truly remarkable scientific journey and undoubtedly the most significant scientific discovery of the twenty-first century so far. Its experimental confirmation turned out to be a monumental task requiring the creation of an accelerator and experiments of unprecedented capability and complexity, designed to discern the signatures that correspond to the Higgs boson. Thousands of scientists and engineers, in each of the ATLAS and CMS teams, came together from all four corners of the world to make this massive discovery possible.

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.

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.

Erythema gyratum atrophicans transiens neonatale.

An unknown dermatosis was observed in an infant girl. During the newborn period, she had a generalized, patchy, erythematous eruption of about 60 round erythematous patches on the trunk, thighs, head, labial mucosa, and palate. After a few weeks, the lesions became whitish, atrophic, and depressed, and they were surrounded by an erythematous and slightly infiltrated border, which was occasionally lobulated. Histologically, the lesions demonstrated a thin epidermis overlying an edematous dermis. Around the border of the lesions the collagen bundles were infiltrated with mononuclear cells. Granular deposits of IgG, C'3, and C'4 were found at the dermoepidermal junction and around the superficial capillaries. The lesions healed completely and spontaneously within a year.

Benign cephalic histiocytosis.

Benign cephalic histiocytosis is a self-healing non-X, nonlipid cutaneous histiocytosis of children, characterized by a papular eruption on the head. Mucous membranes and viscera are always spared. In the 13 cases reported herein, the children were otherwise in good general health. The disease appeared during the first three years of life, and spontaneous regression was complete by the age of nine years in the four cases healed to date. The histiocytic infiltrate was localized in the upper and middle dermis and contained no lipids at any stage of evolution. All the histiocytes contained coated vesicles, and 5% to 30% also contained comma-shaped bodies in their cytoplasm.

[Chloracne due to tetrachloro-2,3,7,8-dibenzo-p-dioxin in children (author's transl)]. / Chloracné au tétrachloro-2,3,7,8-dibenzo-p-dioxine chez les enfants.

Several cases of chloric acne have been observed in children after the accidental Seveso TCDD intoxication. The lesions consist in an inflammatory hyperkeratotic erythema of exposed areas, with numerous horny cysts, sometimes associated with granuloma annulare aspects of the hands. All lesions have the same histological pattern and atrophoderma vermiculata is often their ultimate evolution. These cases are similar to the epidemic follicular keratosis observed in 1946 around Bâle in Switzerland; thus the clinical and genetic evolution of these patients may be foreseen.

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.

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.

[Infantile papular acrodermatitis. Acrodermatitis papulosa and the infantile papulovesicular acrolocalized syndrome]. / Die infantilen papulösen Akrodermatitiden. Die Akrodermatitis papulosa und das infantile papulovesikulöse akrolokalisierte Syndrom

Papular acrodermatitis of childhood is an infectious disease characterized by a non-relapsing, non-itching, monomorphic erythemato-papular dermatitis limited to the face and limbs. It is always associated with anacute hepatitis, with hepatitis B antigen in the serum and with a reactive reticulohistiocytic lymphadenitis. In childhood other types of papular or papulovesicular acro-located eruptions, itching or non-itching, associated with reactive lymphadenitis, are observed, in the course of known diseases and with unknown cause. These acro-located cutaneous eruptions of unknown origin, which show varying features, should be classified as "papulovesicular acrolocated syndrome" until their ethiopathogenesis is known.

Papular acrodermatitis of childhood and other papulo-vesicular acro-located syndromes.

Papular acrodermatitis of childhood (PAC), first recognized in Milan and described by Gianotti in 1955, is an infectious disease of childhood, of low infectivity, fairly widespread, and characterized by: (1) Non-relapsing erythemato-papular dermatitis localized to the face and limbs, lasting about 3 weeks. (2) Paracortical hyperplasia of lymph-nodes. (3) Acute hepatitis, usually anicteric, which lasts at least 2 months and may progress to chronic liver disease.

Akrodermatitis papulosa infantilis. An Australia antigen disease.

Several items characterize the papular acrodermatitis: 1. the clinical picture and the localisation 2. inguinal and axillary lymphadenitis 3. acute usually anicteric hepatitis 4. presence of hepatitis B antigen in all patients. Other members of the family are carriers of HB-Ag, too. One of them usually had icteric hepatitis weeks before or after PAC. At present we consider PAC as the clinical disease due to the primary infection of HB-Ag in childhood. The cycle of HB Ag is shown in a scheme. It suggests why the disease is rare, asymptomatic infections occurring in the majority of the cases. It appears in children without HB-antibodies and a particular reactive condition. After parenteral inoculation PAC and lymphadenitis do not develop. Some chronic HB Ag carriers may have become so after PAC in the childhood.

[The infantile acrodermatitis syndrome and Epstein-Barr virus infection]. / Das infantile Akrodermatitis-Syndrom und Epstein-Barr-Virus-Infektion.

Six cases of APVS, associated with Epstein-Barr-Virus-infection are reported, the clinical picture, however, is not diagnosed as it is in acrodermatitis papulosa infantum (API). For this reason, we suggest to look for the signs of a primary viral infection in all cases of acro-localized papulo-vesicular skin manifestations. In contrast of APVS, API is a primary hepatitis B virus infection.

Histiocytic syndromes: a review.

Histiocytoses represent a large, puzzling group of rare skin diseases. The purpose of this review is to schematically outline the clinical, histologic, and ultrastructural features of the most important histiocytic syndromes and to provide the pertinent differential diagnoses. For convenience, we have followed the criterion suggested by Winkelmann, distinguishing these conditions into X and non-X. Among the non-X histiocytoses the self-healing forms have been treated first; the progressive forms follow.

Some ultrastructural aspects of lymph-node cells and hepatocytes in papular acrodermatitis of childhood.

Ultrastructural examination of the inguinal lymph-nodes of six patients with papular acrodermatitis of childhood with hepatitis B antigenemia showed the presence of several Langerhans cells and, in three cases, the presence of some mononucleate cells, the cytoplasm of which contained groups of 20-50 spherical particles, approximately 150 A in diameter and with an electron-dense core. In the hepatocytes of two of these patients we observed spherical particles ranging in size between 150 A and 220 A, having an electron-lucent core and scattered throughout areas limited by a membrane.