567 research outputs found

    A Toy Model for Testing Finite Element Methods to Simulate Extreme-Mass-Ratio Binary Systems

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    Extreme mass ratio binary systems, binaries involving stellar mass objects orbiting massive black holes, are considered to be a primary source of gravitational radiation to be detected by the space-based interferometer LISA. The numerical modelling of these binary systems is extremely challenging because the scales involved expand over several orders of magnitude. One needs to handle large wavelength scales comparable to the size of the massive black hole and, at the same time, to resolve the scales in the vicinity of the small companion where radiation reaction effects play a crucial role. Adaptive finite element methods, in which quantitative control of errors is achieved automatically by finite element mesh adaptivity based on posteriori error estimation, are a natural choice that has great potential for achieving the high level of adaptivity required in these simulations. To demonstrate this, we present the results of simulations of a toy model, consisting of a point-like source orbiting a black hole under the action of a scalar gravitational field.Comment: 29 pages, 37 figures. RevTeX 4.0. Minor changes to match the published versio

    FEniCS-HPC: Automated predictive high-performance finite element computing with applications in aerodynamics

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    Developing multiphysics finite element methods (FEM) and scalable HPC implementations can be very challenging in terms of software complexity and performance, even more so with the addition of goal-oriented adaptive mesh refinement. To manage the complexity we in this work present general adaptive stabilized methods with automated implementation in the FEniCS-HPC automated open source software framework. This allows taking the weak form of a partial differential equation (PDE) as input in near-mathematical notation and automatically generating the low-level implementation source code and auxiliary equations and quantities necessary for the adaptivity. We demonstrate new optimal strong scaling results for the whole adaptive framework applied to turbulent flow on massively parallel architectures down to 25000 vertices per core with ca. 5000 cores with the MPI-based PETSc backend and for assembly down to 500 vertices per core with ca. 20000 cores with the PGAS-based JANPACK backend. As a demonstration of the power of the combination of the scalability together with the adaptive methodology allowing prediction of gross quantities in turbulent flow we present an application in aerodynamics of a full DLR-F11 aircraft in connection with the HiLift-PW2 benchmarking workshop with good match to experiments

    Demographic patterns and outcomes of patients in level I trauma centers in three international trauma systems

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    Introduction: Trauma systems were developed to improve the care for the injured. The designation and elements comprising these systems vary across countries. In this study, we have compared the demographic patterns and patient outcomes of Level I trauma centers in three international trauma systems. Methods: International multicenter prospective trauma registry-based study, performed in the University Medical Center Utrecht (UMCU), Utrecht, the Netherlands, John Hunter Hospital (JHH), Newcastle, Australia, and Harborview Medical Center (HMC), Seattle, the United States. Inclusion: patients =18 years, admitted in 2012, registered in the institutional trauma registry. Results: In UMCU, JHH, and HMC, respectively, 955, 1146, and 4049 patients met the inclusion criteria of which 300, 412, and 1375 patients with Injury Severity Score (ISS) > 15. Mean ISS was higher in JHH (13.5; p < 0.001) and HMC (13.4; p < 0.001) compared to UMCU (11.7). Unadjusted mortality: UMCU = 6.5 %, JHH = 3.6 %, and HMC = 4.8 %. Adjusted odds of death: JHH = 0.498 [95 % confidence interval (CI) 0.303-0.818] and HMC = 0.473 (95 % CI 0.325-0.690) compared to UMCU. HMC compared to JHH was 1.002 (95 % CI 0.664-1.514). Odds of death patients ISS > 15: JHH = 0.507 (95 % CI 0.300-0.857) and HMC = 0.451 (95 % CI 0.297-0.683) compared to UMCU. HMC = 0.931 (95 % CI 0.608-1.425) compared to JHH. TRISS analysis: UMCU: Ws = 0.787, Z = 1.31, M = 0.87; JHH, Ws = 3.583, Z = 6.7, M = 0.89; HMC, Ws = 3.902, Z = 14.6, M = 0.84. Conclusion: This study demonstrated substantial differences across centers in patient characteristics and mortality, mainly of neurological cause. Future research must investigate whether the outcome differences remain with nonfatal and long-term outcomes. Furthermore, we must focus on the development of a more valid method to compare systems

    A profile of hospital-admitted paediatric burns patients in South Africa

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    <p>Abstract</p> <p>Background</p> <p>Injuries and deaths from burns are a serious, yet preventable health problem globally. This paper describes burns in a cohort of children admitted to the Red Cross Children's Hospital, in Cape Town, South Africa.</p> <p>This six month retrospective case note review looked at a sample of consecutively admitted patients from the 1 <sup>st </sup>April 2007 to the 30 <sup>th </sup>September 2007. Information was collected using a project-specific data capture sheet. Descriptive statistics (percentages, medians, means and standard deviations) were calculated, and data was compared between age groups. Spearman's correlation co-efficient was employed to look at the association between the total body surface area and the length of stay in hospital.</p> <p>Findings</p> <p>During the study period, 294 children were admitted (f= 115 (39.1%), m= 179 (60.9%)). Hot liquids caused 83.0% of the burns and 36.0% of these occurred in children aged two years or younger. Children over the age of five were equally susceptible to hot liquid burns, but the mechanism differed from that which caused burns in the younger child.</p> <p>Conclusion</p> <p>In South Africa, most hospitalised burnt children came from informal settlements where home safety is a low priority. Black babies and toddlers are most at risk for sustaining severe burns when their environment is disorganized with respect to safety. Burns injuries can be prevented by improving the home environment and socio-economic living conditions through the health, social welfare, education and housing departments.</p

    Children admitted to hospital following unintentional injury: perspectives of health service providers in Aotearoa/New Zealand

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    <p>Abstract</p> <p>Background</p> <p>Unintentional injuries are the leading cause of death and hospitalisation among New Zealand children, with indigenous Māori and ethnic minority Pacific children significantly over represented in these statistics. International research has shown that many children hospitalised for injury, as well as their families experience high levels of stress, and ethnic disparities in the quality of trauma care are not uncommon. The research on which this paper is based sought to identify key issues and concerns for New Zealand's multi-ethnic community following hospitalisation for childhood injury in order to inform efforts to improve the quality of trauma services. This paper reports on service providers' perspectives complementing previously published research on the experiences of families of injured children.</p> <p>Methods</p> <p>A qualitative research design involving eleven in-depth individual interviews and three focus groups was used to elicit the views of 21 purposefully selected service provider key informants from a range of professional backgrounds involved in the care and support of injured children and their families in Auckland, New Zealand. Interviews were transcribed and data were analysed using thematic analysis.</p> <p>Results</p> <p>Key issues identified by service providers included limited ability to meet the needs of children with mild injuries, particularly their emotional needs; lack of psychological support for families; some issues related to Māori and Pacific family support services; lack of accessible and comprehensive information for children and families; poor staff continuity and coordination; and poor coordination of hospital and community services, including inadequacies in follow-up plans. There was considerable agreement between these issues and those identified by the participant families.</p> <p>Conclusions</p> <p>The identified issues and barriers indicate the need for interventions for service improvement at systemic, provider and patient levels. Of particular relevance are strategies that enable families to have better access to information, including culturally appropriate oral and written sources; improve communication amongst staff and between staff and families; and carefully developed discharge plans that provide care continuity across boundaries between hospital and community settings. Māori and Pacific family support services are important and need better resourcing and support from an organisational culture responsive to the needs of these populations.</p

    Subtype-Selective Small Molecule Inhibitors Reveal a Fundamental Role for Nav1.7 in Nociceptor Electrogenesis, Axonal Conduction and Presynaptic Release.

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    Human genetic studies show that the voltage gated sodium channel 1.7 (Nav1.7) is a key molecular determinant of pain sensation. However, defining the Nav1.7 contribution to nociceptive signalling has been hampered by a lack of selective inhibitors. Here we report two potent and selective arylsulfonamide Nav1.7 inhibitors; PF-05198007 and PF-05089771, which we have used to directly interrogate Nav1.7's role in nociceptor physiology. We report that Nav1.7 is the predominant functional TTX-sensitive Nav in mouse and human nociceptors and contributes to the initiation and the upstroke phase of the nociceptor action potential. Moreover, we confirm a role for Nav1.7 in influencing synaptic transmission in the dorsal horn of the spinal cord as well as peripheral neuropeptide release in the skin. These findings demonstrate multiple contributions of Nav1.7 to nociceptor signalling and shed new light on the relative functional contribution of this channel to peripheral and central noxious signal transmission.The funder provided support in the form of salaries for authors [AA, AB, MC, JT, MM, AW, EP, AG, PJC, RD, DP, ZL, BM, CW, NS, RS, PS, NC, DK, RB, ES], but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section
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