337 research outputs found
An ASKAP Search for a Radio Counterpart to the First High-significance Neutron Star-Black Hole Merger LIGO/Virgo S190814bv
We present results from a search for a radio transient associated with the LIGO/Virgo source S190814bv, a likely neutron star-black hole (NSBH) merger, with the Australian Square Kilometre Array Pathfinder. We imaged a 30 deg2 field at ΔT = 2, 9, and 33 days post-merger at a frequency of 944 MHz, comparing them to reference images from the Rapid ASKAP Continuum Survey observed 110 days prior to the event. Each epoch of our observations covers 89% of the LIGO/Virgo localization region. We conducted an untargeted search for radio transients in this field, resulting in 21 candidates. For one of these, AT2019osy, we performed multiwavelength follow-up and ultimately ruled out the association with S190814bv. All other candidates are likely unrelated variables, but we cannot conclusively rule them out. We discuss our results in the context of model predictions for radio emission from NSBH mergers and place constrains on the circum-merger density and inclination angle of the merger. This survey is simultaneously the first large-scale radio follow-up of an NSBH merger, and the most sensitive widefield radio transients search to-date. © 2019. The American Astronomical Society. All rights reserved
'We don't learn democracy, we live it!' : consulting the pupil voice in Scottish schools
As the education for citizenship agenda continues to impact on schools, there is a need to begin the discussion around examining the kind of initiatives that can push it forward. In Scotland the proposals should, it is argued, permeate the curriculum throughout the school. Yet there is the fear that the responsibility of all can become the responsibility of none. This paper examines, through case study research carried out by the authors, initiatives in schools designed to take forward the citizenship agenda in the light of children's rights. The first two relate to firstly the impact of pupil councils in primary schools and secondly the impact of discussing controversial issues in the primary classroom. The third outlines the impact on values and dispositions of developing more participatory, democratic practice in the classroom. The paper concludes by calling for both more initiatives of this type and more evaluation of their worth
MWA rapid follow-up of gravitational wave transients: prospects for detecting prompt radio counterparts
We present and evaluate the prospects for detecting coherent radio
counterparts to gravitational wave (GW) events using Murchison Widefield Array
(MWA) triggered observations. The MWA rapid-response system, combined with its
buffering mode ( minutes negative latency), enables us to catch any
radio signals produced from seconds prior to hours after a binary neutron star
(BNS) merger. The large field of view of the MWA ( at
120\,MHz) and its location under the high sensitivity sky region of the
LIGO-Virgo-KAGRA (LVK) detector network, forecast a high chance of being
on-target for a GW event. We consider three observing configurations for the
MWA to follow up GW BNS merger events, including a single dipole per tile, the
full array, and four sub-arrays. We then perform a population synthesis of BNS
systems to predict the radio detectable fraction of GW events using these
configurations. We find that the configuration with four sub-arrays is the best
compromise between sky coverage and sensitivity as it is capable of placing
meaningful constraints on the radio emission from 12.6\% of GW BNS detections.
Based on the timescales of four BNS merger coherent radio emission models, we
propose an observing strategy that involves triggering the buffering mode to
target coherent signals emitted prior to, during or shortly following the
merger, which is then followed by continued recording for up to three hours to
target later time post-merger emission. We expect MWA to trigger on
BNS merger events during the LVK O4 observing run, which
could potentially result in two detections of predicted coherent emission.Comment: Accepted for publication in PAS
Luminous Millimeter, Radio, and X-Ray Emission from ZTF 20acigmel (AT 2020xnd)
Photometric and spectroscopic data for two Low Luminosity Type IIP Supernovae (LL SNe IIP) 2020cxd and 2021aai are presented. SN 2020cxd was discovered 2 d after explosion at an absolute magnitude of Mr = −14.02 ± 0.21 mag, subsequently settling on a plateau which lasts for ∼120 d. Through the luminosity of the late light curve tail, we infer a synthesized 56Ni mass of (1.8 ± 0.5) × 10−3 M⊙. During the early evolutionary phases, optical spectra show a blue continuum (T>8000 K) with broad Balmer lines displaying a P Cygni profile, while at later phases, Ca II, Fe II, Sc II, and Ba II lines dominate the spectra. Hydrodynamical modelling of the observables yields R≃ 575 R⊙ for the progenitor star, with Mej = 7.5 M⊙ and E≃ 0.097 foe emitted during the explosion. This low-energy event originating from a low-mass progenitor star is compatible with both the explosion of a red supergiant (RSG) star and with an Electron Capture Supernova arising from a super asymptotic giant branch star. SN 2021aai reaches a maximum luminosity of Mr = −16.57 ± 0.23 mag (correcting for AV = 1.92 mag), at the end of its remarkably long plateau (∼140 d). The estimated 56Ni mass is (1.4 ± 0.5) × 10−2 M⊙. The expansion velocities are compatible with those of other LL SNe IIP (few 103 km s−1). The physical parameters obtained through hydrodynamical modelling are R≃ 575 R⊙, Mej = 15.5 M⊙, and E = 0.4 foe. SN 2021aai is therefore interpreted as the explosion of an RSG, with properties that bridge the class of LL SNe IIP with standard SN IIP events
A retrospective analysis of noise-induced hearing loss in the Dutch construction industry
Purpose Noise exposure is an important and highly prevalent occupational hazard in the construction industry. This study examines hearing threshold levels of a large population of Dutch construction workers and compares their hearing thresholds to those predicted by ISO-1999. Methods In this retrospective study, medical records of periodic occupational health examinations of 29,644 construction workers are analysed. Pure-tone audiometric thresholds of noise-exposed workers are compared to a non-exposed control group and to ISO-1999 predictions. Regression analyses are conducted to explore the relationship between hearing loss and noise intensity, noise exposure time and the use of hearing protection. Results Noise-exposed workers had greater hearing losses compared to their non-noise-exposed colleagues and to the reference population reported in ISO-1999. Noise exposure explained only a small proportion of hearing loss. When the daily noise exposure level rose from 80 dB(A) towards 96 dB(A), only a minor increase in hearing loss is shown. The relation of exposure time and hearing loss found was similar to ISO-1999 predictions when looking at durations of 10 years or more. For the first decade, the population medians show poorer hearing than predicted by ISO-1999. Discussion Duration of noise exposure was a better predictor than noise exposure levels, probably because of the limitations in noise exposure estimations. In this population, noise-induced hearing loss was already present at the beginning of employment and increased at the same rate as is predicted for longer exposure duration
Middle Neolithic pits and a burial at West Amesbury, Wiltshire
Excavations on the south-eastern slopes of King Barrow Ridge, 1.5 km east of Stonehenge, revealed five pits, a grave and other features of Middle Neolithic date. Analysis of the pit assemblages and the partial inhumation interred in the grave has provided insights into lifeways in this landscape in the late fourth millennium cal BC. Evidence suggests that the area was visited by a pastoralist, mobile community on a semi-regular basis for a significant period, in late autumn or winter. Selected remnants of craft-working and consumption were deposited in pits, before deliberate infilling. These depositions repeatedly memorialised activity on the hillside at a time of contemporary activity elsewhere on King Barrow Ridge and at the future site of Stonehenge. Middle Neolithic pits are present in significant numbers across King Barrow Ridge, and alongside pits in the Durrington area, form one of the densest concentrations of such activity in the region. Long distance mobility is suggested by the possible Irish origins of the inhumation, the first Middle Neolithic individual excavated in the environs of Stonehenge. Whilst of significance for understanding the Middle Neolithic in the WHS and the region, this research also hints at the roots of Late Neolithic monumentalisation of this landscape
Systematic reviews of complementary therapies - an annotated bibliography. Part 1: Acupuncture
Background Complementary therapies are widespread but controversial. We aim to provide a comprehensive collection and a summary of systematic reviews of clinical trials in three major complementary therapies (acupuncture, herbal medicine, homeopathy). This article is dealing with acupuncture. Potentially relevant reviews were searched through the register of the Cochrane Complementary Medicine Field, the Cochrane Library, Medline, and bibliographies of articles and books. To be included articles had to review prospective clinical trials of acupuncture; had to describe review methods explicitly; had to be published; and had to focus on treatment effects. Information on conditions, interventions, methods, results and conclusions was extracted using a pretested form and summarized descriptively. Results From a total of 48 potentially relevant reviews preselected in a screeening process 39 met the inclusion criteria. 22 were on various pain syndromes or rheumatic diseases. Other topics addressed by more than one review were addiction, nausea, asthma and tinnitus. Almost unanimously the reviews state that acupuncture trials include too few patients. Often included trials are heterogeneous regarding patients, interventions and outcome measures, are considered to have insufficient quality and contradictory results. Convincing evidence is available only for postoperative nausea, for which acupuncture appears to be of benefit, and smoking cessation, where acupuncture is no more effective than sham acupuncture. Conclusions A large number of systematic reviews on acupuncture exists. What is most obvious from these reviews is the need for (the funding of) well-designed, larger clinical trials
Efficacy and safety of bilateral continuous theta burst stimulation (cTBS) for the treatment of chronic tinnitus: design of a three-armed randomized controlled trial
<p>Abstract</p> <p>Background</p> <p>Tinnitus, the perception of sound and noise in absence of an auditory stimulus, has been shown to be associated with maladaptive neuronal reorganization and increased activity of the temporoparietal cortex. Transient modulation of tinnitus by repetitive transcranial magnetic stimulation (rTMS) indicated that these areas are critically involved in the pathophysiology of tinnitus and suggested new treatment strategies. However, the therapeutic efficacy of rTMS in tinnitus is still unclear, individual response is variable, and the optimal stimulation area disputable. Recently, continuous theta burst stimulation (cTBS) has been put forward as an effective rTMS protocol for the reduction of pathologically enhanced cortical excitability.</p> <p>Methods</p> <p>48 patients with chronic subjective tinnitus will be included in this randomized, placebo controlled, three-arm trial. The treatment consists of two trains of cTBS applied bilaterally to the secondary auditory cortex, the temporoparietal associaction cortex, or to the lower occiput (sham condition) every working day for four weeks. Primary outcome measure is the change of tinnitus distress as quantified by the Tinnitus Questionnaire (TQ). Secondary outcome measures are tinnitus loudness and annoyance as well as tinnitus change during and after treatment. Audiologic and speech audiometric measurements will be performed to assess potential side effects. The aim of the present trail is to investigate effectiveness and safety of a four weeks cTBS treatment on chronic tinnitus and to compare two areas of stimulation. The results will contribute to clarify the therapeutic capacity of rTMS in tinnitus.</p> <p>Trial registration</p> <p>The trial was registered with the clinical trials register of <url>http://www.clinicaltrials.gov</url> (NCT00518024).</p
Unexpected combination of acute croup and myocarditis: Case report
BACKGROUND: Lower vaccination coverage among foreign-born children is of concern because they live in households and communities characterized by more intense exposure to infectious diseases. Because of their higher prevalence rates, there is an increasing occurrence of infectious diseases imported into developed countries. This case report emphasizes the emerging necessity for new clinicians and pathologists of having competence with old infectious disease pathology. CASE PRESENTATION: A three and a half year old girl, who presented with croup history of 5 days and has been in severe respiratory distress, was admitted to the Pediatric Intensive Care Unit in shock and acute respiratory failure. The patient was immediately intubated, and a grayish nonadherent membrane extending through the glottis down into the larynx was apparent during the procedure. Echocardiographic findings, which were consistent with acute myocarditis, confirmed poor left ventricular contractility despite escalating high doses of inotropes. Autopsy showed numerous strains of toxigenic corynobacterium diphtheriae, which also grew on the Loeffler cultures of membranes received during the intubation. CONCLUSION: It is critical that new generations of clinicians and bio-pathologists not only be trained in the subspecialty of infectious disease pathology, but that they also be willing participants in the diagnosis and investigation of infectious diseases
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