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.

Very-high-energy particle acceleration powered by the jets of the microquasar SS 433.

SS 433 is a binary system containing a supergiant star that is overflowing its Roche lobe with matter accreting onto a compact object (either a black hole or neutron star)1-3. Two jets of ionized matter with a bulk velocity of approximately 0.26c (where c is the speed of light in vacuum) extend from the binary, perpendicular to the line of sight, and terminate inside W50, a supernova remnant that is being distorted by the jets2,4-8. SS 433 differs from other microquasars (small-scale versions of quasars that are present within our own Galaxy) in that the accretion is believed to be super-Eddington9-11, and the luminosity of the system is about 1040 ergs per second2,9,12,13. The lobes of W50 in which the jets terminate, about 40 parsecs from the central source, are expected to accelerate charged particles, and indeed radio and X-ray emission consistent with electron synchrotron emission in a magnetic field have been observed14-16. At higher energies (greater than 100 gigaelectronvolts), the particle fluxes of γ-rays from X-ray hotspots around SS 433 have been reported as flux upper limits6,17-20. In this energy regime, it has been unclear whether the emission is dominated by electrons that are interacting with photons from the cosmic microwave background through inverse-Compton scattering or by protons that are interacting with the ambient gas. Here we report teraelectronvolt γ-ray observations of the SS 433/W50 system that spatially resolve the lobes. The teraelectronvolt emission is localized to structures in the lobes, far from the centre of the system where the jets are formed. We have measured photon energies of at least 25 teraelectronvolts, and these are certainly not Doppler-boosted, because of the viewing geometry. We conclude that the emission-from radio to teraelectronvolt energies-is consistent with a single population of electrons with energies extending to at least hundreds of teraelectronvolts in a magnetic field of about 16 microgauss.

Publisher Correction: Very-high-energy particle acceleration powered by the jets of the microquasar SS 433.

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Sublingual ultrasound as an assessment method for predicting difficult intubation: a pilot study.

Current methods to assess the airway before tracheal intubation are variable in their ability to predict a difficult airway accurately. We hypothesised that sublingual ultrasound could provide additional information to predict a difficult airway with greater success than current methods. We recruited 110 patients to perform sublingual ultrasound on themselves following brief instruction. Ability to view the hyoid bone on sublingual ultrasound, mouth opening distance, thyromental distance, neck mobility, size of mandible and modified Mallampati classification were recorded and assessed for ability to predict a difficult intubation based on the grade of laryngoscope. Visibility of the hyoid using ultrasound was associated with a laryngoscopic grade of 1-2 (p < 0.0001), and (p < 0.0001) had a positive likelihood ratio of 21.6 and a negative likelihood ratio of 0.28. Each of the other methods had considerably lower positive likelihood ratios and lower sensitivity. Our results suggest that sublingual ultrasound is a potential tool for predicting a difficult airway in addition to conventional methods.

Extended gamma-ray sources around pulsars constrain the origin of the positron flux at Earth.

The unexpectedly high flux of cosmic-ray positrons detected at Earth may originate from nearby astrophysical sources, dark matter, or unknown processes of cosmic-ray secondary production. We report the detection, using the High-Altitude Water Cherenkov Observatory (HAWC), of extended tera-electron volt gamma-ray emission coincident with the locations of two nearby middle-aged pulsars (Geminga and PSR B0656+14). The HAWC observations demonstrate that these pulsars are indeed local sources of accelerated leptons, but the measured tera-electron volt emission profile constrains the diffusion of particles away from these sources to be much slower than previously assumed. We demonstrate that the leptons emitted by these objects are therefore unlikely to be the origin of the excess positrons, which may have a more exotic origin.

A new class of tunable hypersonic phononic crystals based on polymer-tethered colloids.

The design and engineering of hybrid materials exhibiting tailored phononic band gaps are fundamentally relevant to innovative material technologies in areas ranging from acoustics to thermo-optic devices. Phononic hybridization gaps, originating from the anti-crossing between local resonant and propagating modes, have attracted particular interest because of their relative robustness to structural disorder and the associated benefit to 'manufacturability'. Although hybridization gap materials are well known, their economic fabrication and efficient control of the gap frequency have remained elusive because of the limited property variability and expensive fabrication methodologies. Here we report a new strategy to realize hybridization gap materials by harnessing the 'anisotropic elasticity' across the particle-polymer interface in densely polymer-tethered colloidal particles. Theoretical and Brillouin scattering analysis confirm both the robustness to disorder and the tunability of the resulting hybridization gap and provide guidelines for the economic synthesis of new materials with deliberately controlled gap position and width frequencies.

Merosin-deficient congenital muscular dystrophy in two siblings.

Congenital muscular dystrophies are a group of heterogeneous inherited autosomal recessive disorders. The so-called 'pure' or 'occidental' form is further divided into merosin-positive and merosin-negative subgroups. Merosin is also expressed in the nervous system and its deficiency could affect development of the nervous system. The authors report two siblings with merosin-negative congenital muscular dystrophy. The clinical picture, biopsy findings, and abnormalities as detected by the magnetic resonance imaging of the two patients are presented.

Thrombotic thrombocytopenic purpura as a rare complication in childhood systemic lupus erythematosus: case report and literature review.

Thrombotic thrombocytopenic purpura is a rare but serious condition in childhood. It can be idiopathic or a complication of other diseases or drug therapy. We report on a 12-year-old Chinese girl who presented with fulminant systemic lupus erythematosus with progressive renal failure, pancytopenia, and cerebral dysfunction due to thrombotic thrombocytopenic purpura. The patient also had Pneumocystis carinii pneumonia, Pseudomonas septicaemia, and Herpes zoster infections as a result of immunosuppressive treatment. She responded to combined therapy with pulse methylprednisolone, cyclophosphamide, plasmapheresis, and intensive care support, and completely recovered renal and neurological function. A review of the English-language medical literature since 1968 identified 20 other paediatric cases of systemic lupus erythematosus and thrombotic thrombocytopenic purpura. Clinical features, treatment, and outcome of these cases are presented and discussed. Early recognition is important, and although plasmapheresis is not of proven benefit in severe cases of systemic lupus erythematosus, it is life-saving in lupus-related thrombotic thrombocytopenic purpura and must be instituted early to avoid a poor outcome.

Detection of pulsed gamma rays above 100 GeV from the Crab pulsar.

We report the detection of pulsed gamma rays from the Crab pulsar at energies above 100 giga-electron volts (GeV) with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) array of atmospheric Cherenkov telescopes. The detection cannot be explained on the basis of current pulsar models. The photon spectrum of pulsed emission between 100 mega-electron volts and 400 GeV is described by a broken power law that is statistically preferred over a power law with an exponential cutoff. It is unlikely that the observation can be explained by invoking curvature radiation as the origin of the observed gamma rays above 100 GeV. Our findings require that these gamma rays be produced more than 10 stellar radii from the neutron star.

Radio imaging of the very-high-energy gamma-ray emission region in the central engine of a radio galaxy.

The accretion of matter onto a massive black hole is believed to feed the relativistic plasma jets found in many active galactic nuclei (AGN). Although some AGN accelerate particles to energies exceeding 10(12) electron volts and are bright sources of very-high-energy (VHE) gamma-ray emission, it is not yet known where the VHE emission originates. Here we report on radio and VHE observations of the radio galaxy Messier 87, revealing a period of extremely strong VHE gamma-ray flares accompanied by a strong increase of the radio flux from its nucleus. These results imply that charged particles are accelerated to very high energies in the immediate vicinity of the black hole.

Splenic rupture in a newborn.

Traumatic rupture of the spleen in the newborn is a rare event and is seldom reported in the literature. It can occur to an abnormally enlarged spleen or to a normal spleen. In the latter, it usually is associated with difficult delivery. Previously, the majority of patients died probably because of delayed or missed diagnoses. The classic presentation is a triad of bleeding, abdominal distension, and hemoperitoneum. High index of suspicion and improvement in diagnostic tools like ultrasonography and computed tomography are important contributions in early diagnosis so that appropriate treatment can be implemented. Splenectomy is no longer the standard treatment because it increases the chance of postsplenectomy sepsis. Instead, treatment should aim for hemostasis and preservation of spleen. The authors present a case of traumatic rupture of spleen in a normal newborn with normal labor and delivery. The first symptom began at 16 hours of age and evolved to a full-blown classic picture. The baby was saved without splenectomy, and the recovery was smooth and uneventful. This is probably the first reported case of a patient treated without splenectomy in this locality. Discussion of the condition and review of the literature also are presented.