40 research outputs found

    Multi-messenger observations of a binary neutron star merger

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    On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

    Inherited determinants of Crohn's disease and ulcerative colitis phenotypes: a genetic association study

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    Crohn's disease and ulcerative colitis are the two major forms of inflammatory bowel disease; treatment strategies have historically been determined by this binary categorisation. Genetic studies have identified 163 susceptibility loci for inflammatory bowel disease, mostly shared between Crohn's disease and ulcerative colitis. We undertook the largest genotype association study, to date, in widely used clinical subphenotypes of inflammatory bowel disease with the goal of further understanding the biological relations between diseases

    Controlled study of EMG activity of the jaw closers and openers during mastication in patients with myasthenia gravis

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    Mastication was evaluated in patients with bulbar myasthenia gravis and compared with that of patients with ocular myasthenia gravis, patients in remission who previously suffered from bulbar symptoms, and healthy controls. Bulbar myasthenia gravis may impair mastication due to weakness of the masticatory muscles. The aim of the study was to objectively evaluate the influence of myasthenia gravis on mastication. The subjects chewed a piece of breakfast cake and chewed 1 min on a piece of chewing gum. Surface EMG of the masseter muscle, temporalis muscle and jaw opener muscles was recorded. Statistical analysis revealed that bulbar patients produced significantly less EMG activity in the closing phase of a chewing cycle in both experiments. The EMG of the masseter muscle expressed as percentage of the maximum EMG during maximal clenching showed significantly higher values in the bulbar group than in the other groups. This was not found for the temporalis muscle. It was suggested that bulbar patients use a strategy of limited effort to produce a bolus that can be swallowed. The ocular patients and the patients in remission showed no subclinical impairments in muscle function during chewing

    Controlled study of EMG activity of the jaw closers and openers during mastication in patients with myasthenia gravis

    No full text
    Mastication was evaluated in patients with bulbar myasthenia gravis and compared with that of patients with ocular myasthenia gravis, patients in remission who previously suffered from bulbar symptoms, and healthy controls. Bulbar myasthenia gravis may impair mastication due to weakness of the masticatory muscles. The aim of the study was to objectively evaluate the influence of myasthenia gravis on mastication. The subjects chewed a piece of breakfast cake and chewed 1 min on a piece of chewing gum. Surface EMG of the masseter muscle, temporalis muscle and jaw opener muscles was recorded. Statistical analysis revealed that bulbar patients produced significantly less EMG activity in the closing phase of a chewing cycle in both experiments. The EMG of the masseter muscle expressed as percentage of the maximum EMG during maximal clenching showed significantly higher values in the bulbar group than in the other groups. This was not found for the temporalis muscle. It was suggested that bulbar patients use a strategy of limited effort to produce a bolus that can be swallowed. The ocular patients and the patients in remission showed no subclinical impairments in muscle function during chewing
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