Multi-messenger observations of a binary neutron star merger

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

Multi-messenger Observations of a Binary Neutron Star Merger

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 {M}ȯ . 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 NGC 4993 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.</p

Function After Spinal Treatment, Exercise, and Rehabilitation Cost-Effectiveness Analysis Based on a Randomized Controlled Trial

Study Design. Cost-effectiveness analysis alongside a factorial randomized controlled trial.Objective. To assess the cost-effectiveness of a rehabilitation program and/or an education booklet each compared with usual care for the postoperative management of patients undergoing discectomy or lateral nerve root decompression surgery.Summary of Background Data. There is little knowledge about the cost-effectiveness of postoperative management of patients after spinal surgery.Methods. A total of 338 patients were recruited into the study between June 2005 and March 2009. Patients were randomized to rehabilitation only, booklet only, rehabilitation plus booklet, or usual care only. Interactions between booklet and rehabilitation were nonsignificant; hence, we compare booklet versus no booklet and rehabilitation versus no rehabilitation. We adopt an English National Health Service and personal social services perspective. Data on outcomes and costs are based on patient level data from the trial. A 1-year time horizon was used. Outcomes were measured in terms of quality-adjusted life years. Health-related quality of life was reported by patients using the EuroQol-5D (EQ-5D). A comprehensive range of health service contacts were included in the cost analysis.Results. There were no significant differences in costs or outcomes associated with either intervention. Mean incremental costs and mean quality-adjusted life years gained per patient of booklet versus no booklet were -87 pound (95% CI: -1221 pound to 1047) pound and -0.023 (95% CI: -0.068 to 0.023), respectively. Figures for rehabilitation versus no rehabilitation were 160 pound (95% CI: -984 pound to 1304) pound and 0.002 (95% CI: -0.044 to 0.048), respectively. Neither intervention was cost-effective when compared with the threshold range commonly used to judge whether or not an intervention is cost-effective in the English National Health Service.Conclusion. Cost-effectiveness evidence does not support use of booklet over no booklet or rehabilitation over no rehabilitation for the postoperative management of patients after spinal surgery