Search for Gamma-Ray Spectral Lines from Dark Matter Annihilation up to 100 TeV toward the Galactic Center with MAGIC.

Linelike features in TeV γ rays constitute a "smoking gun" for TeV-scale particle dark matter and new physics. Probing the Galactic Center region with ground-based Cherenkov telescopes enables the search for TeV spectral features in immediate association with a dense dark matter reservoir at a sensitivity out of reach for satellite γ-ray detectors, and direct detection and collider experiments. We report on 223 hours of observations of the Galactic Center region with the MAGIC stereoscopic telescope system reaching γ-ray energies up to 100 TeV. We improved the sensitivity to spectral lines at high energies using large-zenith-angle observations and a novel background modeling method within a maximum-likelihood analysis in the energy domain. No linelike spectral feature is found in our analysis. Therefore, we constrain the cross section for dark matter annihilation into two photons to ⟨σv⟩≲5×10^{-28} cm^{3} s^{-1} at 1 TeV and ⟨σv⟩≲1×10^{-25} cm^{3} s^{-1} at 100 TeV, achieving the best limits to date for a dark matter mass above 20 TeV and a cuspy dark matter profile at the Galactic Center. Finally, we use the derived limits for both cuspy and cored dark matter profiles to constrain supersymmetric wino models.

Bounds on Lorentz Invariance Violation from MAGIC Observation of GRB 190114C.

On January 14, 2019, the Major Atmospheric Gamma Imaging Cherenkov telescopes detected GRB 190114C above 0.2 TeV, recording the most energetic photons ever observed from a gamma-ray burst. We use this unique observation to probe an energy dependence of the speed of light in vacuo for photons as predicted by several quantum gravity models. Based on a set of assumptions on the possible intrinsic spectral and temporal evolution, we obtain competitive lower limits on the quadratic leading order of speed of light modification.

Compact radio emission indicates a structured jet was produced by a binary neutron star merger.

The binary neutron star merger event GW170817 was detected through both electromagnetic radiation and gravitational waves. Its afterglow emission may have been produced by either a narrow relativistic jet or an isotropic outflow. High-spatial-resolution measurements of the source size and displacement can discriminate between these scenarios. We present very-long-baseline interferometry observations, performed 207.4 days after the merger by using a global network of 32 radio telescopes. The apparent source size is constrained to be smaller than 2.5 milli-arc seconds at the 90% confidence level. This excludes the isotropic outflow scenario, which would have produced a larger apparent size, indicating that GW170817 produced a structured relativistic jet. Our rate calculations show that at least 10% of neutron star mergers produce such a jet.

Spectroscopic identification of r-process nucleosynthesis in a double neutron-star merger.

The merger of two neutron stars is predicted to give rise to three major detectable phenomena: a short burst of γ-rays, a gravitational-wave signal, and a transient optical-near-infrared source powered by the synthesis of large amounts of very heavy elements via rapid neutron capture (the r-process). Such transients, named 'macronovae' or 'kilonovae', are believed to be centres of production of rare elements such as gold and platinum. The most compelling evidence so far for a kilonova was a very faint near-infrared rebrightening in the afterglow of a short γ-ray burst at redshift z = 0.356, although findings indicating bluer events have been reported. Here we report the spectral identification and describe the physical properties of a bright kilonova associated with the gravitational-wave source GW170817 and γ-ray burst GRB 170817A associated with a galaxy at a distance of 40 megaparsecs from Earth. Using a series of spectra from ground-based observatories covering the wavelength range from the ultraviolet to the near-infrared, we find that the kilonova is characterized by rapidly expanding ejecta with spectral features similar to those predicted by current models. The ejecta is optically thick early on, with a velocity of about 0.2 times light speed, and reaches a radius of about 50 astronomical units in only 1.5 days. As the ejecta expands, broad absorption-like lines appear on the spectral continuum, indicating atomic species produced by nucleosynthesis that occurs in the post-merger fast-moving dynamical ejecta and in two slower (0.05 times light speed) wind regions. Comparison with spectral models suggests that the merger ejected 0.03 to 0.05 solar masses of material, including high-opacity lanthanides.

Swift and NuSTAR observations of GW170817: Detection of a blue kilonova.

With the first direct detection of merging black holes in 2015, the era of gravitational wave (GW) astrophysics began. A complete picture of compact object mergers, however, requires the detection of an electromagnetic (EM) counterpart. We report ultraviolet (UV) and x-ray observations by Swift and the Nuclear Spectroscopic Telescope Array of the EM counterpart of the binary neutron star merger GW170817. The bright, rapidly fading UV emission indicates a high mass (≈0.03 solar masses) wind-driven outflow with moderate electron fraction (Ye ≈ 0.27). Combined with the x-ray limits, we favor an observer viewing angle of ≈30° away from the orbital rotation axis, which avoids both obscuration from the heaviest elements in the orbital plane and a direct view of any ultrarelativistic, highly collimated ejecta (a γ-ray burst afterglow).

GRB 130427A: a nearby ordinary monster.

Long-duration gamma-ray bursts (GRBs) are an extremely rare outcome of the collapse of massive stars and are typically found in the distant universe. Because of its intrinsic luminosity (L ~ 3 × 10(53) ergs per second) and its relative proximity (z = 0.34), GRB 130427A reached the highest fluence observed in the γ-ray band. Here, we present a comprehensive multiwavelength view of GRB 130427A with Swift, the 2-meter Liverpool and Faulkes telescopes, and by other ground-based facilities, highlighting the evolution of the burst emission from the prompt to the afterglow phase. The properties of GRB 130427A are similar to those of the most luminous, high-redshift GRBs, suggesting that a common central engine is responsible for producing GRBs in both the contemporary and the early universe and over the full range of GRB isotropic energies.

The unusual gamma-ray burst GRB 101225A explained as a minor body falling onto a neutron star.

The tidal disruption of a solar-mass star around a supermassive black hole has been extensively studied analytically and numerically. In these events, the star develops into an elongated banana-shaped structure. After completing an eccentric orbit, the bound debris falls into the black hole, forming an accretion disk and emitting radiation. The same process may occur on planetary scales if a minor body passes too close to its star. In the Solar System, comets fall directly into our Sun or onto planets. If the star is a compact object, the minor body can become tidally disrupted. Indeed, one of the first mechanisms invoked to produce strong gamma-ray emission involved accretion of comets onto neutron stars in our Galaxy. Here we report that the peculiarities of the 'Christmas' gamma-ray burst (GRB 101225A) can be explained by a tidal disruption event of a minor body around an isolated Galactic neutron star. This would indicate either that minor bodies can be captured by compact stellar remnants more frequently than occurs in the Solar System or that minor-body formation is relatively easy around millisecond radio pulsars. A peculiar supernova associated with a gamma-ray burst provides an alternative explanation.

Relativistic jet activity from the tidal disruption of a star by a massive black hole.

Supermassive black holes have powerful gravitational fields with strong gradients that can destroy stars that get too close, producing a bright flare in ultraviolet and X-ray spectral regions from stellar debris that forms an accretion disk around the black hole. The aftermath of this process may have been seen several times over the past two decades in the form of sparsely sampled, slowly fading emission from distant galaxies, but the onset of the stellar disruption event has not hitherto been observed. Here we report observations of a bright X-ray flare from the extragalactic transient Swift J164449.3+573451. This source increased in brightness in the X-ray band by a factor of at least 10,000 since 1990 and by a factor of at least 100 since early 2010. We conclude that we have captured the onset of relativistic jet activity from a supermassive black hole. A companion paper comes to similar conclusions on the basis of radio observations. This event is probably due to the tidal disruption of a star falling into a supermassive black hole, but the detailed behaviour differs from current theoretical models of such events.

GRB 090423 at a redshift of z approximately 8.1.

Gamma-ray bursts (GRBs) are produced by rare types of massive stellar explosion. Their rapidly fading afterglows are often bright enough at optical wavelengths that they are detectable at cosmological distances. Hitherto, the highest known redshift for a GRB was z = 6.7 (ref. 1), for GRB 080913, and for a galaxy was z = 6.96 (ref. 2). Here we report observations of GRB 090423 and the near-infrared spectroscopic measurement of its redshift, z = 8.1(-0.3)(+0.1). This burst happened when the Universe was only about 4 per cent of its current age. Its properties are similar to those of GRBs observed at low/intermediate redshifts, suggesting that the mechanisms and progenitors that gave rise to this burst about 600,000,000 years after the Big Bang are not markedly different from those producing GRBs about 10,000,000,000 years later.

Broadband observations of the naked-eye gamma-ray burst GRB 080319B.

Long-duration gamma-ray bursts (GRBs) release copious amounts of energy across the entire electromagnetic spectrum, and so provide a window into the process of black hole formation from the collapse of massive stars. Previous early optical observations of even the most exceptional GRBs (990123 and 030329) lacked both the temporal resolution to probe the optical flash in detail and the accuracy needed to trace the transition from the prompt emission within the outflow to external shocks caused by interaction with the progenitor environment. Here we report observations of the extraordinarily bright prompt optical and gamma-ray emission of GRB 080319B that provide diagnostics within seconds of its formation, followed by broadband observations of the afterglow decay that continued for weeks. We show that the prompt emission stems from a single physical region, implying an extremely relativistic outflow that propagates within the narrow inner core of a two-component jet.

Screening of health care workers for hepatitis B virus and hepatitis C virus: criteria for fitness for work.

The aim of this study was to propose a protocol for assessment of markers of infection with hepatitis B virus (HBV) and hepatitis C virus (HCV) in exposed health care professionals and to define criteria for evaluation of fitness for the job of the infected personnel. The study comprised 800 persons involved in operative procedures, including 414 surgeons, 275 nurses, and 111 anaesthetists. A graduated protocol was created for monitoring markers of HBV and HCV infection. A well-defined combination of markers of antigen-antibody systems enabled identification of four groups of persons with HBV infection differing in fitness for work: 1) HBsAg-positive, HBeAg-positive, HBV DNA-positive; 2) HBsAg-positive, anti-HBe-positive, HBV DNA-positive; 3) HBsAg-positive, anti-HBe-positive, HBV DNA-negative; and 4) anti-HBs-positive, anti-HBc-positive, anti-HBe-positive group. For HCV infection, two groups with different job fitness were identified: 1) anti-HCV-positive, HCV RNA-negative and 2) anti-HCV-positive, HCV RNA-positive. Screening of hospital personnel at risk to HBV and HCV infection requires a well-defined protocol which may help to evaluate the fitness of the infected personnel for a specific job.

[Use of diverse diagnostic techniques in the study of silicosis]. / Utilizzo di diverse tecniche diagnostiche nello studio della silicosi.

This study would examine the efficiency of different diagnostic tools, imaging and functional, in the study of pulmonary system of workers exposed to silicotigen dusts. 24 male miners were examined with chest H.R.T.C., spirometry with study of DLCO and of total lung capacity. 13 of 24 miners were submitted to pulmonary ventilatory scintigraphy (99mTcDTPA). All 24 miners were previously yet submitted to two follow-up by means of chest radiography in conformity with ILO guidelines. The chest radiography, even evaluated in conformity with ILO guidelines, is subject to remarkable differences when performed and reported by different operator. Useful data are provided by functional studies. H.R.T.C. is necessary to evaluate the degree of parenchymal involvement and for medicolegal porpoises. Scintigraphy with 99mTc DTPA need of further studies in the evaluation of exposure to silicotigen dusts.

Gardening work and heavy metals in urban environment.

Urban soil may be a source of occupational exposure to various pollutants in gardening and land cultivation. This paper presents data of a one-year follow-up of lead, cadmium, nickel, chromium, and vanadium in the environment of the city of Bologna. Samples of soil and leaves were collected at three locations; gardens from the inner-city high-traffic area, parks in moderate-traffic area, and parks in suburban, low-traffic area. The top and deeper layers of soil and leaves were mainly polluted by lead at all locations, which corresponded to the traffic density. Personal samplers recorded greater concentrations of airborne metals than did the area samplers but the values kept below the threshold limit established by the American Conference of Governmental Industrial Hygienists for the working environment. Due to cumulative nature and interactive effects of toxic metals with other toxic and essential elements, long-term exposure to metals in the urban environment may be a health risk for occupationally exposed gardeners.

Ocular hypertonia and crystalline lens opacities in healthcare workers exposed to ionising radiation.

Some activities performed by healthcare workers may still involve total or partial exposure to ionising radiation exceeding the limit values. In addition to the appearance of crystalline lens opacities which may lead to rays-cataract, recent studies have indicated possible induction of ocular hypertonia in occupationally exposed subjects. The aim of this study was to establish the actual prevalence of ocular hypertonia and crystalline lens opacities in a group of healthcare workers exposed to ionising radiation. The collected data failed to show significant risk of ocular hypertonia and suggested that crystalline lens opacity was not an important indicator of exposure. Notwithstanding, preventive and periodic (every 5 years) ophthalmologic control may prove helpful for medicolegal purposes. Namely, such control would record congenital crystalline lens opacities in many individuals and would thus rule out unjustified claims of occupational disease due to exposure to ionising radiation. Additionally, ophthalmologic control should focus on different and probably more important ocular risks for the radiologists such as the ocular fatigue resulting from a prolonged use of a video display terminal or other diagnostic screens or electrodiaphanoscopes.

[Percutaneous mechanical revascularization of chronic iliac artery occlusion with "first intention" stent placement]. / Rivascolarizzazione meccanica percutanea delle occlusioni croniche dell'arteria iliaca mediante posizionamento "di prima intenzione" di stent.

INTRODUCTION: Percutaneous treatment of chronic iliac artery occlusion has not yet gained complete acceptance as the method of choice. The reason of this widespread skepticism are the poor results achieved with angioplasty and/or lysis therapy. The introduction of stents seems to open new perspectives to percutaneous treatment and the latest follow-up studies report encouraging results. MATERIAL AND METHODS: We report our personal experience in percutaneous mechanical revascularization of chronic iliac occlusion with primary stent placement in 29 patients with 2 years' maximum follow-up. Clinically the patients had at least 3 months' claudication and were in Fontaine stages II to IV. The occlusion was passed mechanically using a hydrophilic guide wire, through the contralateral access in 19 cases and ipsilaterally in 10. The stents were primarily implanted in the last 12 patients; in the first 15 patients, after dilatation with undersized balloons, 25 Wallstent and 12 Palmaz stents were implanted. Each patient underwent color Doppler follow-up for 3-24 months. Nine patients underwent angiography too, after one year. RESULTS: The mechanical passage of the guide-wire through the occluded segment was successful in 27 of 29 (93.1%) patients referred for percutaneous revascularization of a chronic occlusion of the iliac artery. The stent was placed and immediate patency was achieved in 100% of these 27 patients. Clinical improvement was of two stages in 24 patients and of one stage in 3 patients. The follow-up showed neither reocclusions nor critical stenoses of the restored iliac segment. Five embolic complications (5%) occurred after angioplasty, all of them treated percutaneously; surgery was never necessary. DISCUSSION AND CONCLUSIONS: The follow-up studies published in the literature in the last few years and our personal experience encourage the percutaneous treatment of chronic iliac artery occlusions. Percutaneous mechanical revascularization with primary stent positioning can be proposed because it is a reliable and efficacious tool, particularly in young patients in whom a surgical aortoiliac or aortofemoral bypass might injure the pudendal plexis and cause sexual disturbances.

Cumulative trauma disorders of the upper limbs in workers on an agricultural farm.

The work associated with repetitive efforts and inadequate resting periods, strong physical exertion, awkward postures or static positioning exposes workers to the risk of cumulative trauma disorders of the upper limbs. These risk factors are present in many agricultural activities. A study was carried out among workers on an agricultural farm. The workers' histories were taken and they were given periodical medical check-ups. The presence of upper limb disorders was shown in a group of workers. A sample of 42 people was selected for the study by means of specific tests: electromyography, ultrasonography and laser-doppler flowmetry. The tests showed a high incidence of carpal tunnel syndrome and microcirculation disorders. The study confirmed that electromyography, ultrasonography and/or laser-doppler flowmetry are highly useful tools for identifying cumulative trauma disorders.

Physician liaisons increase admissions.

Faced with a crunch on inpatient admissions, hospitals are re-examining relationships with their medical staffs to strengthen physician loyalty. A physician liaison program lets a hospital address both its physicians' and patients' needs. The author discusses the benefits of a physician detail program and offers strategies for success.

Developing a remote practice office.

Remote practice offices (RPOs) offer unique opportunities for hospitals and physicians to increase market share from targeted areas where previously only limited demand existed. This article discusses the benefits and explores the fundamentals of developing a remote practice office.