11,814 research outputs found
System configuration and executive requirements specifications for reusable shuttle and space station/base
System configuration and executive requirements specifications for reusable shuttle and space station/bas
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Assessing time knowledge in children aged 10 to 11 years
The acquisition of time knowledge involves learning how to read clocks, estimate time, read dates and learn about temporal sequences. Evidence suggests that many of these competencies are acquired by 10 years of age although not all children may follow this developmental path. The main purpose of this study was to collect normative data for a screening tool that assesses time knowledge. These data identify the prevalence and pattern of difficulties with time knowledge among a UK sample of Year 6 pupils (aged 10 to 11 years). The Time Screening Assessment tool (Doran, Dutt & Pembery, 2015), designed to assess time knowledge, was administered individually to a sample of 79 children. Findings revealed a median overall score of 32 out of a maximum score of 36. 25% of children performed at or close to ceiling, however seven children scored more than -1.5 standard deviations below the mean. The value of these findings to practitioners working with children in schools is discussed
Capture and Decay of Electroweak WIMPonium
The spectrum of Weakly-Interacting-Massive-Particle (WIMP) dark matter
generically possesses bound states when the WIMP mass becomes sufficiently
large relative to the mass of the electroweak gauge bosons. The presence of
these bound states enhances the annihilation rate via resonances in the
Sommerfeld enhancement, but they can also be produced directly with the
emission of a low-energy photon. In this work we compute the rate for SU(2)
triplet dark matter (the wino) to bind into WIMPonium -- which is possible via
single-photon emission for wino masses above 5 TeV for relative velocity v <
O(10^{-2}) -- and study the subsequent decays of these bound states. We present
results with applications beyond the wino case, e.g. for dark matter inhabiting
a nonabelian dark sector; these include analytic capture and transition rates
for general dark sectors in the limit of vanishing force carrier mass,
efficient numerical routines for calculating positive and negative-energy
eigenstates of a Hamiltonian containing interactions with both massive and
massless force carriers, and a study of the scaling of bound state formation in
the short-range Hulthen potential. In the specific case of the wino, we find
that the rate for bound state formation is suppressed relative to direct
annihilation, and so provides only a small correction to the overall
annihilation rate. The soft photons radiated by the capture process and by
bound state transitions could permit measurement of the dark matter's quantum
numbers; for wino-like dark matter, such photons are rare, but might be
observable by a future ground-based gamma-ray telescope combining large
effective area and a low energy threshold.Comment: 3rd version. An interference sign fixed and changes propagated
through the paper. Topline qualitative conclusions unchange
Lessons from crossing symmetry at large N
20 pages, v2: Assumptions stated more clearly, version published in JHEPWe consider the four-point correlator of the stress tensor multiplet in N=4 SYM. We construct all solutions consistent with crossing symmetry in the limit of large central charge c ~ N^2 and large g^2 N. While we find an infinite tower of solutions, we argue most of them are suppressed by an extra scale \Delta_{gap} and are consistent with the upper bounds for the scaling dimension of unprotected operators observed in the numerical superconformal bootstrap at large central charge. These solutions organize as a double expansion in 1/c and 1/\Delta_{gap}. Our solutions are valid to leading order in 1/c and to all orders in 1/\Delta_{gap} and reproduce, in particular, instanton corrections previously found. Furthermore, we find a connection between such upper bounds and positivity constraints arising from causality in flat space. Finally, we show that certain relations derived from causality constraints for scattering in AdS follow from crossing symmetry.Peer reviewe
Implications of CoGeNT and DAMA for Light WIMP Dark Matter
In this paper, we study the recent excess of low energy events observed by
the CoGeNT collaboration, and discuss the possibility that these events
originate from the elastic scattering of a light (m_DM ~ 5-10 GeV) dark matter
particle. We find that such a dark matter candidate may also be capable of
generating the annual modulation reported by DAMA, as well as the small excess
recently reported by CDMS, without conflicting with the null results from other
experiments, such as XENON10. A dark matter interpretation of the CoGeNT and
DAMA observations favors a region of parameter space that is especially
attractive within the context of Asymmetric Dark Matter models. In such models,
the cosmological dark matter density arises from the baryon asymmetry of the
universe, naturally leading to the expectation that m_DM ~ 1-10 GeV. We also
discuss neutralino dark matter from extended supersymmetric frameworks, such as
the NMSSM. Lastly, we explore the implications of such a dark matter candidate
for indirect searches, and find that the prospects for detecting the neutrino
and gamma ray annihilation products of such a particle to be very encouraging.Comment: 16 pages, 14 figures. v2: references added, fig 4 and surrounding
discussion modified
Protocol for the United Kingdom Rotator Cuff Study (UKUFF) : a randomised controlled trial of open and arthroscopic rotator cuff repair
This project was funded by the NIHR Health Technology Assessment programme (project number 05/47/02). J. L. Rees has received a grant from Oxford University which is related to this paper. J. Dawson reports that Oxford University has received a grant from HTA which is related to this paper, as well as a study grant.Peer reviewedPublisher PD
Prehospital critical care is associated with increased survival in adult trauma patients in Scotland
Background Scotland has three prehospital critical care teams (PHCCTs) providing enhanced care support to a usually paramedic-delivered ambulance service. The effect of the PHCCTs on patient survival following trauma in Scotland is not currently known nationally. Methods National registry-based retrospective cohort study using 2011-2016 data from the Scottish Trauma Audit Group. 30-day mortality was compared between groups after multivariate analysis to account for confounding variables. Results Our data set comprised 17 157 patients, with a mean age of 54.7 years and 8206 (57.5%) of male gender. 2877 patients in the registry were excluded due to incomplete data on their level of prehospital care, leaving an eligible group of 14 280. 13 504 injured adults who received care from ambulance clinicians (paramedics or technicians) were compared with 776 whose care included input from a PHCCT. The median Injury Severity Score (ISS) across all eligible patients was 9; 3076 patients (21.5%) met the ISS>15 criterion for major trauma. Patients in the PHCCT cohort were statistically significantly (all p < 0.01) more likely to be male; be transported to a prospective Major Trauma Centre; have suffered major trauma; have suffered a severe head injury; be transported by air and be intubated prior to arrival in hospital. Following multivariate analysis, the OR for 30-day mortality for patients seen by a PHCCT was 0.56 (95% CI 0.36 to 0.86, p=0.01). Conclusion Prehospital care provided by a physician-led critical care team was associated with an increased chance of survival at 30 days when compared with care provided by ambulance clinicians
Measuring extraordinary rendition and international cooperation
Following the launch of the War on Terror, the United States of America established a global rendition network that saw the transfer of US Central Intelligence Agency terrorist suspects to secret detention sites across the world. There has been considerable debate over how many countries participated in rendition, secret detention and interrogation during the post-9/11 period, and conventional accounts of foreign complicity suggest that diverse countries were involved, including many established democracies. However, research on rendition has continually suffered from uncertainty, a lack of data, and systematic empirical evidence due to the secret nature of counterterrorism cooperation. In this article, I argue that it is possible to study the practice of rendition, unlike many other forms of clandestine security cooperation, as it is partially observable. Specifically, suspected extraordinary rendition flight paths can be tracked using publicly available flight data. This article uses the world’s largest set of public flight data relating to rendition to estimate cross-country collaboration in rendition, secret detention and interrogation. The result suggests 307 likely rendition flights and 15 new participating countries beyond the 54 known cases, with cross validation tests demonstrating high levels of model accuracy. </jats:p
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