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.

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.

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.

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.

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.

Pityriasis rubra pilaris in childhood: a long-term study of 29 cases.

Pityriasis rubra pilaris (PRP) is a dermatosis of unknown origin with a limited frequency in childhood (0.2% of our hospitalized pediatric patients). During the last 20 years we have observed 31 new cases; follow-up has been conducted in 29 children. The acute self-resolving form seems to be the most frequent in children, compared to adults. No cases of hereditary PRP have been observed, and no relationship between the severity of PRP and its prognosis has been reported. Since juvenile PRP has a relatively rapid course and a spontaneous resolution (a few months), it seems unnecessary to use potentially harmful drugs. Synthetic retinoids may be employed in patients whose disease is both persistent and disabling.

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.

Long-term follow-up of dermatitis herpetiformis in children.

Dermatitis herpetiformis was diagnosed in seventy-six children by its clinical features and by detection of granular IgA deposits in the papillary dermis of perilesional skin. Enteric alterations demonstrated by measurement of D-xylose absorption and by small intestinal biopsies were detected in over 90% of all patients. A complete follow-up was obtained for all children who were followed for 3 to 10 years. Treatment with a gluten-free diet alone led to a reversal of the intestinal abnormality in 100% of our children and to the disappearance of cutaneous lesions in 82% of reported cases. This suggests that a complete remission of symptoms can be obtained with a gluten-free diet alone. Dapsone alone is effective therapy for the rash but does not affect the intestinal alterations. Furthermore, the lack of side effects to dietetic therapy for a long period of time makes the diet the treatment of choice in this disease.

Acute hepatitis B in children with papular acrodermatitis.

Thirteen children who had repeated liver biopsies over a period of 2-16 years after the onset of papular acrodermatitis (PAC) were studied retrospectively. Six patients, rebiopsied within 36 months after the onset of PAC, had histologic evidence of chronic periportal hepatitis. However, repeated biopsies in 3 of the patients revealed a normal liver or chronic portal hepatitis. Whereas all patients had at the end of the observation markers of hepatitis B virus infection, 8 of the 10 patients studied had HBs antigenemia. These data indicate that severe active liver disease may regress without treatment in patients who have had PAC. However, the high frequency of a chronic HBsAg-carrier state among these patients suggests either an inefficient clearance of the virus or an altered immune reaction.

[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.

Purpura de Finkelstein (edema agudo hemorragico del lactante). / Finkelstein's purpura (acute hemorrhagic edema in the infant)

Se presenta un caso de purpura de Finkelstein en un nino de nueve meses. Es de destacar el antecedente de una infeccion inespecifica de las vias aereas superiores Su clinica es muy particular: evolucion aguda de lesiones equimoticas, simetricas, de contornos policiclicos con tipica disposicion acral; edema palpebral intenso con ausencia de manifestaciones sistemicas El laboratorio no revela datos de importancia y faltan trastornos en el mecanismo de la coagulacion. Histologicamente se trata de tipica vasculitis leucocitoclasica. La importancia de esta entidad radica en su diagnostico diferencial con patologias mas frecuentes, especialmente con el eritema polimorfo y la purpura de Scholein-Henoch; o con enfermedades graves como el lupus eritematoso sistemico neonatal y la meningococemia con purpura.Su aparente gravedad clinica contrasta con el buen estado general y su evolucion autoresolutiva en el termino de una a dos semanas.Se concluye que la etiologia relacionada con farmacos o bacterias no ha podido ser establecida, sugiriendose para los nuevos casos una profundizacion de los estudios virologicos

Purpura de Finkelstein (edema agudo hemorragico del lactante). / Finkelsteins purpura (acute hemorrhagic edema in the infant)

Se presenta un caso de purpura de Finkelstein en un nino de nueve meses. Es de destacar el antecedente de una infeccion inespecifica de las vias aereas superiores Su clinica es muy particular: evolucion aguda de lesiones equimoticas, simetricas, de contornos policiclicos con tipica disposicion acral; edema palpebral intenso con ausencia de manifestaciones sistemicas El laboratorio no revela datos de importancia y faltan trastornos en el mecanismo de la coagulacion. Histologicamente se trata de tipica vasculitis leucocitoclasica. La importancia de esta entidad radica en su diagnostico diferencial con patologias mas frecuentes, especialmente con el eritema polimorfo y la purpura de Scholein-Henoch; o con enfermedades graves como el lupus eritematoso sistemico neonatal y la meningococemia con purpura.Su aparente gravedad clinica contrasta con el buen estado general y su evolucion autoresolutiva en el termino de una a dos semanas.Se concluye que la etiologia relacionada con farmacos o bacterias no ha podido ser establecida, sugiriendose para los nuevos casos una profundizacion de los estudios virologicos

Analysis of lipids and dioxin in chloracne due to tetrachloro-2,3,7,8-p-dibenzodioxin.

Biochemical investigations on the lipid and dioxin content of the cysts and comedo-like lesions of three children exposed to tetrachloro-2,3,7,8-p-dibenzodioxin (TCDD) have been performed. Gas chromatography and mass spectrometry failed to demonstrate the presence of dioxin despite the high sensitivity of the method. Further investigation by thin layer and gas chromatography-mass spectrometry showed that the lipids of the chloracne lesions in these children were exclusively epidermal in origin. These findings support the hypothesis that exposure to dioxin produces a hyperproliferative reaction of the cutaneous epithelium with squamous metaplasia of the cells lining the ducts of skin glands.

HLA antigens in juvenile dermatitis herpetiformis.

The incidence of histocompatibility antigens HLA-A, B, C, DR was studied in 32 Italian children with dermatitis herpetiformis. A significantly increased relative risk was found for B8 (R.R.=6.2), which was present in 50% of the patients as against 14% of the controls and for DR3 (R.R.=11.7), present in 69% of the patients as against 16%. DR7 also appeared to be increased, but only among DR3-negative patients. There was no significant difference in the incidence of DR3 between children with abnormal and normal jejunal biopsy, though there does seem to be a difference in expressivity of the intestinal involvement between DR3 apparent homozygous, DR3 heterozygous and DR3-negative patients.