202 research outputs found

    An Extended Burst Tail from SGR 1900+14 with a Thermal X-ray Spectrum

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    The Soft Gamma Repeater, SGR 1900+14, entered a new phase of activity in April 2001 initiated by the intermediate flare recorded on April 18. Ten days following this flare, we discovered an abrupt increase in the source flux between consecutive RXTE orbits. This X-ray flux excess decayed over the next several minutes and was subsequently linked to a high fluence burst from SGR 1900+14 recorded by other spacecraft (Ulysses and KONUS) while the SGR was Earth-occulted for RXTE. We present here spectral and temporal analysis of both the burst of 28 April and the long X-ray tail following it. We find strong evidence of an exclusively thermal X-ray tail in this event and bring this evidence to bear on other bursts and flares from SGR 1900+14 which have shown extended X-ray excesses (e.g. 1998 August 29). We include in this comparison a discussion of the physical origins of SGR bursts and extended X-ray tails.Comment: 27 pages, 13 figures, ApJ submissio

    Final Results From the Circumarctic Lakes Observation Network (CALON) Project

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    Since 2012, the physical and biogeochemical properties of ~60 lakes in northern Alaska have been investigated under CALON, a project to document landscape-scale variability of Arctic lakes in permafrost terrain. The network has ten nodes along two latitudinal transects extending inland 200 km from the Arctic Ocean. A meteorological station is deployed at each node and six representative lakes instrumented and continuously monitored, with winter and summer visits for synoptic assessment of lake conditions. Over the 4-year period, winter and summer climatology varied to create a rich range of lake responses over a short period. For example, winter 2012-13 was very cold with a thin snowpack producing thick ice across the region. Subsequent years had relatively warm winters, yet regionally variable snow resulted in differing gradients of ice thickness. Ice-out timing was unusually late in 2014 and unusually early in 2015. Lakes are typically well–mixed and largely isothermal, with minor thermal stratification occurring in deeper lakes during calm, sunny periods in summer. Lake water temperature records and morphometric data were used to estimate the ground thermal condition beneath 28 lakes. Application of a thermal equilibrium steady-state model suggests a talik penetrating the permafrost under many larger lakes, but lake geochemical data do not indicate a significant contribution of subpermafrost groundwater. Biogeochemical data reveal distinct spatial and seasonal variability in chlorophyll biomass, chromophoric dissolved organic carbon (CDOM), and major cations/anions. Generally, waters sampled beneath ice in April had distinctly higher concentrations of inorganic solutes and methane compared with August. Chlorophyll concentrations and CDOM absorption were higher in April, suggesting significant biological/biogeochemical activity under lake ice. Lakes are a positive source of methane in summer, and some also emit nitrous oxide and carbon dioxide. As part of the Indigenous Knowledge component,76 Iñupiat elders, hunters and berry pickers have been interviewed and over 75 hours of videotaped interviews produced. The video library and searchable interview logs are archived with the North Slope community. All field data is archived at ACADIS, and further information is at www.arcticlakes.org

    Rapid and highly variable warming of lake surface waters around the globe

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    In this first worldwide synthesis of in situ and satellite‐derived lake data, we find that lake summer surface water temperatures rose rapidly (global mean = 0.34°C decade−1) between 1985 and 2009. Our analyses show that surface water warming rates are dependent on combinations of climate and local characteristics, rather than just lake location, leading to the counterintuitive result that regional consistency in lake warming is the exception, rather than the rule. The most rapidly warming lakes are widely geographically distributed, and their warming is associated with interactions among different climatic factors—from seasonally ice‐covered lakes in areas where temperature and solar radiation are increasing while cloud cover is diminishing (0.72°C decade−1) to ice‐free lakes experiencing increases in air temperature and solar radiation (0.53°C decade−1). The pervasive and rapid warming observed here signals the urgent need to incorporate climate impacts into vulnerability assessments and adaptation efforts for lakes

    Comparative study of the two large flares from SGR1900+14 with the BeppoSAX Gamma-Ray Burst Monitor

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    We report on spectral and temporal results of the 40-700 keV observations, obtained with the Gamma-Ray Burst Monitor (GRBM) on board BeppoSAX, of the two large flares from the Soft Gamma-ray Repeater SGR1900+14 occurred on August 27, 1998 and April 18, 2001. From their intensity, fluence and duration, the first one was classified as "giant" and the second as "intermediate". The spectral results have been obtained with an improved response function of the GRBM. We find that the two events have similar spectral properties, but different temporal properties. The major difference concerns the time profiles of the light curves, whereas the lack of evidence in the 2001 flare for the erratic time variability found at high frequencies (10-1000 Hz) in the 1998 flare could be ascribed to lower counting statistics. We discuss these results in the light of the magnetar model proposed for SGR sources.Comment: 15 pages, 20 figures, accepted for publication in A&

    Long-term Anatomical and Functional Results of Robot-Assisted Pelvic Floor Surgery for the Management of Multicompartment Prolapse:A Prospective Study

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    BACKGROUND: Long-term data on robot-assisted sacrocolporectopexy for the treatment of multicompartment pelvic organ prolapse are scarce. With the rising prevalence of prolapse and increasing surgical repair, it is essential to evaluate long-term results. OBJECTIVE: This study aimed to evaluate long-term functional and anatomic outcomes after sacrocolporectopexy. DESIGN: This is a prospective, observational cohort study. SETTINGS: This study was conducted at a teaching hospital with tertiary referral function for patients with gynecological/rectal prolapse. PATIENTS: All patients undergoing robot-assisted sacrocolporectopexy from 2011 to 2012 were included. INTERVENTION: Robot-assisted sacrocolporectopexy was performed. MAIN OUTCOME MEASURES: The primary outcome was the anatomic cure rate after 1 and 4 years, defined as simplified pelvic organ prolapse quantification stage 1 vaginal apical prolapse and no external rectal prolapse or internal rectal prolapse present. Kaplan-Meier curves were used for determination of recurrence-free intervals. Secondary outcomes were functional pelvic floor symptoms (symptoms of bulge, obstructed defecation, fecal incontinence, urogenital distress inventory) and quality of life (Pelvic Floor Impact Questionnaire). RESULTS: Fifty-three patients were included. After 12 and 48 months, the recurrence-free intervals based on Kaplan-Meier estimates were 100% and 90%. In total, there were 10 recurrences: 2 apical and 8 internal rectal prolapses. Symptoms of bulge (94%-12%; p < 0.0005), fecal incontinence (62%-32%; p < 0.0005), obstructed defecation (59%-24%; p = 0.008), and median Pelvic Floor Impact Questionnaire scores (124-5; p = 0.022) improved significantly at final follow-up. Median urogenital distress inventory scores showed improvement after 1 year (30-13; p = 0.021). LIMITATIONS: This was an observational, single-center study with selective postoperative imaging. CONCLUSIONS: Ninety percent of patients were recurrence free 48 months after robot-assisted sacrocolporectopexy. Symptoms of vaginal bulge, quality of life, constipation, and fecal incontinence improved significantly. However, a subgroup of patients showed persistent bowel complaints that underlie the complexity of multicompartment prolapse. See Video Abstract at http://links.lww.com/DCR/B265

    Simulation Workshop to Test STAR: a Home-based Toothbrushing Intervention within Childsmile

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    In Scotland, where socio-economic inequalities in child tooth decay persist, Childsmile’s community-based Dental Health Support Workers (DHSWs) deliver tailored interventions to families in need of additional support in the home setting, including the promotion of supervised toothbrushing in the early years. Aims: The aim of this study was to test the feasibility and acceptability of the STAR toothbrushing tool with DHSWs and families in a simulated setting to support implementation of supervised toothbrushing in the home. Methods: In August 2022, the STAR tool was developed/co-designed with DHSWs. It aims to help families to identify barriers to toothbrushing and provide strategies to overcome these barriers. A two day simulation workshop, was held in Glasgow Dental School, with four DHSWs, two parents and two simulated parents, who tested the acceptability and feasibility of the tool. The simulated interactions between DHSWs and parents were video recorded and analysed using the Function Resonance Analysis Method (FRAM) - a novel approach in this area. Exit interviews with participants were audio recorded and analysed using Framework analysis and the modified Consolidated Framework for Implementation Research (CFIR). Full NHS ethical approval and participant consent were obtained. Results: DHSWs and parents responded positively to the use of the STAR tool and reported it was easy to use and adaptable to families with different barriers to toothbrushing. Six weeks follow-up found that parents had been able to use the strategies given to them to make beneficial changes to their toothbrushing routines. FRAM analysis showed that the STAR tool can be used flexibly by DHSWs to provide tailored toothbrushing advice to families. Conclusions: In this simulation study, use of the STAR tool was feasible and acceptable to DHSWs and parents and allowed families to make improvements to their toothbrushing routines. The STAR tool is currently being rolled out and evaluated across the 14 NHS Scotland Health Boards

    Long-term mesh erosion rate following abdominal robotic reconstructive pelvic floor surgery:a prospective study and overview of the literature

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    Introduction and hypothesis: The use of synthetic mesh in transvaginal pelvic floor surgery has been subject to debate internationally. Although mesh erosion appears to be less associated with an abdominal approach, the long-term outcome has not been studied intensively. This study was set up to determine the long-term mesh erosion rate following abdominal pelvic reconstructive surgery. Methods: A prospective, observational cohort study was conducted in a tertiary care setting. All consecutive female patients who underwent robot-assisted laparoscopic sacrocolpopexy and sacrocolporectopexy in 2011 and 2012 were included. Primary outcome was mesh erosion. Preoperative and postoperative evaluation (6 weeks, 1 year, 5 years) with a clinical examination and questionnaire regarding pelvic floor symptoms was performed. Mesh-related complications were assessed using a transparent vaginal speculum, proctoscopy, and digital vaginal and rectal examination. Kaplan–Meier estimates were calculated for mesh erosion. A review of the literature on mesh exposure after minimally invasive sacrocolpopexy was performed (≄12 months’ follow-up). Results: Ninety-six of the 130 patients included (73.8%) were clinically examined. Median follow-up time was 48.1 months (range 36.0–62.1). Three mesh erosions were diagnosed (3.1%; Kaplan–Meier 4.9%, 95% confidence interval 0–11.0): one bladder erosion for which mesh resection and an omental patch interposition were performed, and two asymptomatic vaginal erosions (at 42.7 and 42.3 months) treated with estrogen cream in one. Additionally, 22 patients responded solely by questionnaire and/or telephone; none reported mesh-related complaints. The literature, mostly based on retrospective studies, described a median mesh erosion rate of 1.9% (range 0–13.3%). Conclusions: The long-term rate of mesh erosion following an abdominally placed synthetic graft is low

    An exceptionally bright flare from SGR1806-20 and the origins of short-duration gamma-ray bursts

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    Soft-gamma-ray repeaters (SGRs) are galactic X-ray stars that emit numerous short-duration (about 0.1 s) bursts of hard X-rays during sporadic active periods. They are thought to be magnetars: strongly magnetized neutron stars with emissions powered by the dissipation of magnetic energy. Here we report the detection of a long (380 s) giant flare from SGR 1806-20, which was much more luminous than any previous transient event observed in our Galaxy. (In the first 0.2 s, the flare released as much energy as the Sun radiates in a quarter of a million years.) Its power can be explained by a catastrophic instability involving global crust failure and magnetic reconnection on a magnetar, with possible large-scale untwisting of magnetic field lines outside the star. From a great distance this event would appear to be a short-duration, hard-spectrum cosmic gamma-ray burst. At least a significant fraction of the mysterious short-duration gamma-ray bursts therefore may come from extragalactic magnetars.Comment: 21 pages, 5 figures. Published in Natur
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