15,135 research outputs found

    The Kaon B-parameter from Quenched Domain-Wall QCD

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    We present numerical results for the kaon B-parameter, B_K, determined in the quenched approximation of lattice QCD. Our simulations are performed using domain-wall fermions and the renormalization group improved, DBW2 gauge action which combine to give quarks with good chiral symmetry at finite lattice spacing. Operators are renormalized non-perturbatively using the RI/MOM scheme. We study scaling by performing the simulation on two different lattices with a^{-1} = 1.982(30) and 2.914(54) GeV. We combine this quenched scaling study with an earlier calculation of B_K using two flavors of dynamical, domain-wall quarks at a single lattice spacing to obtain B_K(MS,NDR,mu=2GeV)=0.563(21)(39)(30), were the first error is statistical, the second systematic (without quenching errors) and the third estimates the error due to quenching.Comment: 77 pages, 44 figures, to be published in Phys. Rev.

    The Effectiveness of a 'Train the Trainer' Model of Resuscitation Education for Rural Peripheral Hospital Doctors in Sri Lanka

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    BACKGROUND Sri Lankan rural doctors based in isolated peripheral hospitals routinely resuscitate critically ill patients but have difficulty accessing training. We tested a train-the-trainer model that could be utilised in isolated rural hospitals. METHODS Eight selected rural hospital non-specialist doctors attended a 2-day instructor course. These "trained trainers" educated their colleagues in advanced cardiac life support at peripheral hospital workshops and we tested their students in resuscitation knowledge and skills pre and post training, and at 6- and 12-weeks. Knowledge was assessed through 30 multiple choice questions (MCQ), and resuscitation skills were assessed by performance in a video recorded simulated scenario of a cardiac arrest using a Resuci Anne Skill Trainer mannequin. RESULTS/DISCUSSION/CONCLUSION Fifty seven doctors were trained. Pre and post training assessment was possible in 51 participants, and 6-week and 12-week follow up was possible for 43, and 38 participants respectively. Mean MCQ scores significantly improved over time (p<0.001), and a significant improvement was noted in "average ventilation volume", "compression count", and "compressions with no error", "adequate depth", "average depth", and "compression rate" (p<0.01). The proportion of participants with compression depth ≥40mm increased post intervention (p<0.05) and at 12-week follow up (p<0.05), and proportion of ventilation volumes between 400-1000mls increased post intervention (p<0.001). A significant increase in the proportion of participants who "checked for responsiveness", "opened the airway", "performed a breathing check", who used the "correct compression ratio", and who used an "appropriate facemask technique" was also noted (p<0.001). A train-the-trainer model of resuscitation education was effective in improving resuscitation knowledge and skills in Sri Lankan rural peripheral hospital doctors. Improvement was sustained to 12 weeks for most components of resuscitation knowledge and skills. Further research is needed to identify which components of training are most effective in leading to sustained improvement in resuscitation.This research was funded by an international collaborative research Wellcome Trust/National Health and Medical Research Council grant GR071669. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

    Geographical Access to Child and Family Healthcare Services and Hospitals for Africa-Born Migrants and Refugees in NSW, Australia; A Spatial Study.

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    Background: African-born migrants and refugees arriving from fragile states and countries with political and economic challenges have unique health needs requiring tailored healthcare services and support. However, there is little investigation into the distribution of this population and their spatial access to healthcare in Australia. This paper reports on research that aimed to map the spatial distribution of Africa-born migrants from low and lower-middle-income countries (LLMICs) and refugees in New South Wales (NSW) and access to universal child and family health (CFH) services and hospitals. Methods: We analysed the Australian Bureau of Statistics 2016 Census data and Department of Social Services 2018 Settlement data. Using a Geographic Information System mapping software (Caliper Corporation. Newton, MA, USA), we applied data visualisation techniques to map the distribution of Africa-born migrants and refugees relative to CFH services and their travel distance to the nearest service. Results: Results indicate a spatial distribution of 51,709 migrants from LLMICs in Africa and 13,661 refugees from Africa live in NSW, with more than 70% of the total population residing in Sydney. The Africa-born migrant and refugee population in Sydney appear to be well served by CFH services and hospitals. However, there is a marked disparity between local government areas. For example, the local government areas of Blacktown and Canterbury-Bankstown, where the largest number of Africa-born migrants and refugees reside, have more uneven and widely dispersed services than those in Sydney’s inner suburbs. Conclusion: The place of residence and travel distance to services may present barriers to access to essential CFH services and hospitals for Africa-born refugees and migrants. Future analysis into spatial-access disadvantages is needed to identify how access to health services can be improved for refugees and migrants

    Construction of the Soudan 2 detector

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    Progress in the construction of the Soudan 2 nucleon decay detector which is being built at the Soudan iron mine in Minnesota is discussed. The expected event rate and characteristics of low energy neutrino events, muon events, multiple muon events, and other cosmic ray phenomena are discussed

    Radiative Neutralino Decay in Supersymmetric Models

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    The radiative decay Z2-> Z1 gamma proceeds at the one-loop level in the MSSM. It can be the dominant decay mode for the second lightest neutralino Z2 in certain regions of parameter space of supersymmetric models, where either a dynamical and/or kinematic enhancement of the branching fraction occurs. We perform an updated numerical study of this decay mode in both the minimal supergravity model (mSUGRA) and in the more general MSSM framework. In mSUGRA, the largest rates are found in the ``focus point'' region, where the mu parameter becomes small, and the lightest neutralinos become higgsino-like; in this case, radiative branching fraction can reach the 1% level. Our MSSM analysis includes a scan over independent positive and negative gaugino masses. We show branching fractions can reach the 10-100% level even for large values of the parameter tan(beta). These regions of parameter space are realized in supergravity models with non-universal gaugino masses. Measurement of the radiative neutralino branching fraction may help pin down underlying parameters of the fundamental supersymmetric model.Comment: 19 page JHEP file with 8 PS figures; previous version contained figure misplacemen

    Modelling windage power loss from an enclosed spur gear

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    Within a gearbox the majority of transmission losses can be attributed to bearing losses, meshing losses, or losses due to windage/churning. In this paper the commercial computational fluid dynamics (CFD) code Fluent 6.2.16 is applied in a two-dimensional study of windage power loss (WPL) from a single spur gear rotating in air. By comparing CFD data to published experimental data appropriate grid density and modelling parameters are identified. The model is used to investigate how peripheral shrouding affects WPL and whether WPL can be reduced through minor modifications to tooth tip geometry. Non-dimensional shroud spacings (ratio of gap to gear PCD) of between 0.005 and 0.05 were investigated at shaft speeds between 5000 and 20 000 r/min. Although CFD data compared reasonably well to experimental data, trends were not reproduced and an optimum shroud could not be identified. A full three-dimensional study is recommended. Modifying the tooth tip by adding a small chamfer on the leading edge reduced WPL by ~6 per cent. A small fillet increased total WPL by a similar amount suggesting that WPL may increase as a gear wears. This preliminary study suggests further work in this area would be beneficial

    Fluctuation limits of strongly degenerate branching systems

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    Functional limit theorems for scaled fluctuations of occupation time processes of a sequence of critical branching particle systems in Rd\R^d with anisotropic space motions and strongly degenerated splitting abilities are proved in the cases of critical and intermediate dimensions. The results show that the limit processes are constant measure-valued Wienner processes with degenerated temporal and simple spatial structures.Comment: 15 page

    Radio observations of the double-relic galaxy cluster Abell 1240

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    We present LOFAR 120 − 168 MHz images of the merging galaxy cluster Abell 1240 that hosts double radio relics. In combination with the GMRT 595 − 629 MHz and VLA 2 − 4 GHz data, we characterised the spectral and polarimetric properties of the radio emission. The spectral indices for the relics steepen from their outer edges towards the cluster centre and the electric field vectors are approximately perpendicular to the major axes of the relics. The results are consistent with the picture that these relics trace large-scale shocks propagating outwards during the merger. Assuming diffusive shock acceleration (DSA), we obtain shock Mach numbers of M = 2.4 and 2.3 for the northern and southern shocks, respectively. For M ≲ 3 shocks, a pre-existing population of mildly relativistic electrons is required to explain the brightness of the relics due to the high (> 10 per cent) particle acceleration efficiency required. However, for M ≳ 4 shocks the required efficiency is ≳ 1% and ≳ 0.5%, respectively, which is low enough for shock acceleration directly from the thermal pool. We used the fractional polarization to constrain the viewing angle to ≥ 53 ± 3° and ≥ 39 ± 5° for the northern and southern shocks, respectively. We found no evidence for diffuse emission in the cluster central region. If the halo spans the entire region between the relics (∼1.8 Mpc) our upper limit on the power is P1.4 GHz = (1.4 ± 0.6) × 1023 W Hz−1 which is approximately equal to the anticipated flux from a cluster of this mass. However, if the halo is smaller than this, our constraints on the power imply that the halo is underluminous

    A Case History of Liquefaction Flow Failures in Mountains Mine Waste Dumps

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    Over the past 25 years there have been a large number of flowslides in Rocky Mountain coal mine waste dumps located in British Columbia, Canada. The flowslides occurred rapidly and displayed surprisingly long distance of runout up to 2 km. Detailed field, laboratory studies, and analyses indicate that static collapse of saturated or nearly saturated sandy gravel layers within the dumps are responsible for the initial failure and ensuing flow failures. In addition to field and laboratory studies, finite element analyses were carried out on three case histories. The analysis results indicated that the flow like liquefaction failures of these waste dumps can be triggered by gradually raising of perched water tables contained within thin layers or poorly draining waste material in these slopes. This paper reviews the site condition and failure pattern observed in the mountainous mine waste dumps and investigates the mechanism of static liquefaction failure by finite element methods

    A microfluidic chip based model for the study of full thickness human intestinal tissue using dual flow

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    © 2016 Author(s). The study of inflammatory bowel disease, including Ulcerative Colitis and Crohn's Disease, has relied largely upon the use of animal or cell culture models; neither of which can represent all aspects of the human pathophysiology. Presented herein is a dual flow microfluidic device which holds full thickness human intestinal tissue in a known orientation. The luminal and serosal sides are independently perfused ex vivo with nutrients with simultaneous waste removal for up to 72 h. The microfluidic device maintains the viability and integrity of the tissue as demonstrated through Haematoxylin & Eosin staining, immunohistochemistry and release of lactate dehydrogenase. In addition, the inflammatory state remains in the tissue after perfusion on the device as determined by measuring calprotectin levels. It is anticipated that this human model will be extremely useful for studying the biology and tes ting novel interventions in diseased tissue
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