1,982 research outputs found

    Measurements and Performance Factor Comparisons of Magnetic Materials at High Frequency

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    The design of power magnetic components for operation at high frequency (HF, 3–30MHz) has been hindered by a lack of performance data and by the limited design theory in that frequency range. To address these deficiencies, we have measured and present core loss data for a variety of commercially available magnetic materials in the HF range. In addition, we extend the theory of performance factor for appropriate use in HF design. Since magnetic materials suitable for HF applications tend to have low permeability, we also consider the impact of low permeability on design. We conclude that, with appropriate material selection and design, increased frequencies can continue to yield improved power density well into the HF regime.MIT Energy Initiative (Lockheed Martin)Texas Instruments Incorporate

    Gribov pendulum in the Coulomb gauge on curved spaces

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    In this paper the generalization of the Gribov pendulum equation in the Coulomb gauge for curved spacetimes is analyzed on static spherically symmetric backgrounds. A rigorous argument for the existence and uniqueness of solution is provided in the asymptotically AdS case. The analysis of the strong and weak boundary conditions is equivalent to analyzing an effective one-dimensional Schrodinger equation. Necessary conditions in order for spherically symmetric backgrounds to admit solutions of the Gribov pendulum equation representing copies of the vacuum satisfying the strong boundary conditions are given. It is shown that asymptotically flat backgrounds do not support solutions of the Gribov pendulum equation of this type, while on asymptotically AdS backgrounds such ambiguities can appear. Some physical consequences are discussed.Comment: 22 pages, no figures. V2: The discussion of the physical consequences has been extended. To appear on Physical Review

    Risk of venous thromboembolism in children after general surgery

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    Background/purpose: The purpose of the study was to determine absolute and relative rates of venous thromboembolism (VTE) following general surgical procedures in children compared to the general population. Methods: We analyzed data from all patients under the age of 18 years in the Clinical Practice Research Datalink, linked to Hospital Episode Statistics from England (2001–2011) undergoing a general surgical procedure and population controls. Crude rates of VTE and adjusted hazard ratios were calculated using Cox regression. Results We identified 15,637 children who had a surgical procedure with 161,594 controls. Six children undergoing surgery had a VTE diagnosed in the year after compared to five children in the population cohort. The overall rate of VTE following surgery was 0.4 per 1000 person years (pyrs) (95% confidence interval [CI] 0.15–0.88) compared to 0.04 per 1000 pyrs (95% CI 0.02–0.09) in the population cohort. This represented a 9 fold increase in risk compared to the population cohort (adjusted hazard ratio [HR] 8.80; 95% CI 2.59–29.94). Conclusions Children are at increased risk for VTE following general surgical procedures compared to the general population however the absolute risk is small and given this the benefits of thromboprophylaxis need to be balanced against the risk of complications following its use

    Design, implementation and evaluation of a national campaign to distribute nine million free LLINs to children under five years of age in Tanzania.

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    BACKGROUND\ud \ud After a national voucher scheme in 2004 provided pregnant women and infants with highly subsidized insecticide-treated nets (ITNs), use among children under five years (U5s) in mainland Tanzania increased from 16% in 2004 to 26.2% in 2007. In 2008, the Ministry of Health and Social Welfare planned a catch-up campaign to rapidly and equitably deliver a free long-lasting insecticidal net (LLIN) to every child under five years in Tanzania.\ud \ud METHODS\ud \ud The ITN Cell, a unit within the National Malaria Control Programme (NMCP), coordinated the campaign on behalf of the Ministry of Health and Social Welfare. Government contractors trained and facilitated local government officials to supervise village-level volunteers on a registration of all U5s and the distribution and issuing of LLINs. The registration results formed the basis for the LLIN order and delivery to village level. Caregivers brought their registration coupons to village issuing posts during a three-day period where they received LLINs for their U5s. Household surveys in five districts assessed ITN ownership and use immediately after the campaign.\ud \ud RESULTS\ud \ud Nine donors contributed to the national campaign that purchased and distributed 9.0 million LLINs at an average cost of $7.07 per LLIN, including all campaign-associated activities. The campaign covered all eight zones of mainland Tanzania, the first region being covered separately during an integrated measles immunization/malaria LLIN distribution in August 2008, and was implemented one zone at a time from March 2009 until May 2010. ITN ownership at household level increased from Tanzania's 2008 national average of 45.7% to 63.4%, with significant regional variations. ITN use among U5s increased from 28.8% to 64.1%, a 2.2-fold increase, with increases ranging from 22.1-38.3% percentage points in different regions.\ud \ud CONCLUSION\ud \ud A national-level LLIN distribution strategy that fully engaged local government authorities helped avoid additional burden on the healthcare system. Distribution costs per net were comparable to other public health interventions. Particularly among rural residents, ITN ownership and use increased significantly for the intended beneficiaries. The upcoming universal LLIN distribution and further behaviour change communication will further improve ITN ownership and use in 2010-2011

    Analysing and Recommending Options for Maintaining Universal Coverage with Long-Lasting Insecticidal Nets: The Case of Tanzania in 2011.

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    Tanzania achieved universal coverage with long-lasting insecticidal nets (LLINs) in October 2011, after three years of free mass net distribution campaigns and is now faced with the challenge of maintaining high coverage as nets wear out and the population grows. A process of exploring options for a continuous or "Keep-Up" distribution system was initiated in early 2011. This paper presents for the first time a comprehensive national process to review the major considerations, findings and recommendations for the implementation of a new strategy. Stakeholder meetings and site visits were conducted in five locations in Tanzania to garner stakeholder input on the proposed distribution systems. Coverage levels for LLINs and their decline over time were modelled using NetCALC software, taking realistic net decay rates, current demographic profiles and other relevant parameters into consideration. Costs of the different distribution systems were estimated using local data. LLIN delivery was considered via mass campaigns, Antenatal Care-Expanded Programme on Immunization (ANC/EPI), community-based distribution, schools, the commercial sector and different combinations of the above. Most approaches appeared unlikely to maintain universal coverage when used alone. Mass campaigns, even when combined with a continuation of the Tanzania National Voucher Scheme (TNVS), would produce large temporal fluctuations in coverage levels; over 10 years this strategy would require 63.3 million LLINs and a total cost of 444millionUSD.Communitymechanisms,whileabletodelivertherequirednumbersofLLINs,wouldrequireamassivescaleupinmonitoring,evaluationandsupervisionsystemstoensureaccurateapplicationofidentificationcriteriaatthecommunitylevel.SchoolbasedapproachescombinedwiththeexistingTNVSwouldreachmostTanzanianhouseholdsanddeliver65.4millionLLINsover10yearsatatotalcostof444 million USD. Community mechanisms, while able to deliver the required numbers of LLINs, would require a massive scale-up in monitoring, evaluation and supervision systems to ensure accurate application of identification criteria at the community level. School-based approaches combined with the existing TNVS would reach most Tanzanian households and deliver 65.4 million LLINs over 10 years at a total cost of 449 million USD and ensure continuous coverage. The cost of each strategy was largely driven by the number of LLINs delivered. The most cost-efficient strategy to maintain universal coverage is one that best optimizes the numbers of LLINs needed over time. A school-based approach using vouchers targeting all students in Standards 1, 3, 5, 7 and Forms 1 and 2 in combination with the TNVS appears to meet best the criteria of effectiveness, equity and efficiency

    Justice Beyond Borders? Australia and the International Criminal Court

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    The International Criminal Court (ICC) came into being on 1 July 2002. A four-person team opened an office in The Hague and will collect reports and allegations of genocide, war crimes and crimes against humanity until judges and a prosecutor are appointed towards the end of 2003. Although the court was heralded by many states and international lawyers as the most important positive development in international law since the formation of the United Nations, it did not get off to an auspicious start. The Bush administration was concerned that US military forces operating overseas would be particularly vulnerable to what it described as 'politicised' prosecutions. It therefore insisted that not only would it not be a part of the ICC, but also that it would not sanction the continuation of UN peacekeeping operations. Closer to home, the Australian Senate only ratified the ICC's founding treaty, the Rome Statute, after a bitter debate that split both the Liberal and National parties. This was the case even though the Howard government-and Foreign Minister Alexander Downer in particular-had been a leading advocate of the court and ratification of the Rome Statute had been a Liberal Party election promise in 2001. The cost that Downer, and pro-ICC Attorney-General Daryl Williams had to pay in order to appease restive conservative backbenchers, the National Party, and an increasingly reluctant (and pro-US) Prime Minister and secure the ratification was a declaration that reaffirmed the primacy of the Australian judicial system over the ICC. The declaration insisted that no Australian would be prosecuted by the court without the consent of the Attomey-General, and asserted Australia's right to define what is meant by the crimes of genocide, war crimes, and crimes against humanity. We argue that although Downer and Williams should be commended for their commitment to international justice, the declaration attached to Australia's ratification was unnecessary and unhelpful. The first and third aspects of the declaration were unnecessary: the principle of complementarity enshrined in the Rome Statute means that the ICC already recognises the primacy of domestic jurisdiction, and the crimes covered are already considered to fall under universal jurisdiction, as the Nuremberg, Tokyo and more recent Pinochet trials showed (see Weller 1999). The second is unhelpful because it contravenes both the letter and the spirit of the Rome Statute. We will begin, then, by tracing the development of the ICC debate in Australian politics. In 1998, the government was an enthusiastic advocate of the court but by 2002 an alliance of an ardently pro-US Prime Minister, vocal right-wing parliamentarians and their supporters, and The Australian (and its foreign affairs editor Greg Sheridan in particular) combined to put ratification in doubt. Contrary to Prime Minister John Howard's claims, this debate was not well informed. Instead, it was characterised by hearsay, inaccuracy and scare-mongering. The subsequent section of the article demonstrates this by focusing on the background to, and creation of, the Rome Statute

    Neurobehavioral consequences of chronic intrauterine opioid exposure in infants and preschool children: a systematic review and meta-analysis

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    <b>Background</b><p></p> It is assumed within the accumulated literature that children born of pregnant opioid dependent mothers have impaired neurobehavioral function as a consequence of chronic intrauterine opioid use.<p></p> <b>Methods</b><p></p> Quantitative and systematic review of the literature on the consequences of chronic maternal opioid use during pregnancy on neurobehavioral function of children was conducted using the Meta-analysis of Observational Studies in Epidemiology (MOOSE) and the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. We searched Cinahl, EMBASE, PsychINFO and MEDLINE between the periods of January 1995 to January 2012.<p></p> <b>Results</b><p></p> There were only 5 studies out of the 200 identified that quantitatively reported on neurobehavioral function of children after maternal opioid use during pregnancy. All 5 were case control studies with the number of exposed subjects within the studies ranging from 33–143 and 45–85 for the controls. This meta-analysis showed no significant impairments, at a non-conservative significance level of p < 0.05, for cognitive, psychomotor or observed behavioural outcomes for chronic intra-uterine exposed infants and pre-school children compared to non-exposed infants and children. However, all domains suggested a trend to poor outcomes in infants/children of opioid using mothers. The magnitude of all possible effects was small according to Cohen’s benchmark criteria.<p></p> <b>Conclusions</b><p></p> Chronic intra-uterine opioid exposed infants and pre-school children experienced no significant impairment in neurobehavioral outcomes when compared to non-exposed peers, although in all domains there was a trend to poorer outcomes. The findings of this review are limited by the small number of studies analysed, the heterogenous populations and small numbers within the individual studies. Longitudinal studies are needed to determine if any neuropsychological impairments appear after the age of 5 years and to help investigate further the role of environmental risk factors on the effect of ‘core’ phenotypes

    Status of Muon Collider Research and Development and Future Plans

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    The status of the research on muon colliders is discussed and plans are outlined for future theoretical and experimental studies. Besides continued work on the parameters of a 3-4 and 0.5 TeV center-of-mass (CoM) energy collider, many studies are now concentrating on a machine near 0.1 TeV (CoM) that could be a factory for the s-channel production of Higgs particles. We discuss the research on the various components in such muon colliders, starting from the proton accelerator needed to generate pions from a heavy-Z target and proceeding through the phase rotation and decay (πμνμ\pi \to \mu \nu_{\mu}) channel, muon cooling, acceleration, storage in a collider ring and the collider detector. We also present theoretical and experimental R & D plans for the next several years that should lead to a better understanding of the design and feasibility issues for all of the components. This report is an update of the progress on the R & D since the Feasibility Study of Muon Colliders presented at the Snowmass'96 Workshop [R. B. Palmer, A. Sessler and A. Tollestrup, Proceedings of the 1996 DPF/DPB Summer Study on High-Energy Physics (Stanford Linear Accelerator Center, Menlo Park, CA, 1997)].Comment: 95 pages, 75 figures. Submitted to Physical Review Special Topics, Accelerators and Beam

    Neopterin and procalcitonin are suitable biomarkers for exclusion of severe Plasmodium falciparum disease at the initial clinical assessment of travellers with imported malaria

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    Background. Most clinicians in developed, non-malaria endemic countries have limited or no experience in making clinical assessments of malaria disease severity and subsequent decisions regarding the need for parenteral therapy or high-level monitoring in febrile patients with imported malaria. In the present study, the diagnostic accuracy of plasma soluble Triggering Receptor Expressed on Myeloid cells 1 (TREM-1), neopterin and procalcitonin levels as biomarkers for severe Plasmodium falciparum disease was evaluated in 104 travellers with imported malaria (26 patients with non-P. falciparum malaria, 64 patients with uncomplicated P. falciparum malaria and 14 patients with severe P. falciparum malaria). Methods. TREM-1, neopterin and procalcitonin were determined in serum using commercially available ELISA or EIA tests. The diagnostic performance of these biomarkers for severe disease was compared with plasma lactate, a well-validated parameter for disease severity in patients with malaria, as reference. Severe malaria was defined according to the modified WHO criteria. Results. No significant differences in TREM-1 levels were detected between the different patient groups. Patients with severe P. falciparum malaria had significantly higher neopterin and procalcitonin levels on admission when compared to patients with uncomplicated P. falciparum malaria or non-P. falciparum malaria. Receiver Operating Characteristic (ROC) curve analysis showed that neopterin had the highest Area-Under-the-ROC curve (AUROC 0.85) compared with plasma lactate (AUROC 0.80) and procalcitonin (AUROC 0.78). At a cut-off point of 10.0 ng/ml, neopterin had a positive and negative predictive value of 0.38 and 0.98 whereas procalcitonin, at a cut-off point of 0.9 ng/ml, had a positive and negative predictive value of 0.30 and 1.00. Conclusion. Although the diagnostic value of neopterin and procalcitonin is limited, the high negative predictive value of both neopterin and procalcitonin may be helpful for a rapid exclusion of severe malaria disease on admission. This may be a valuable tool for physicians only occasionally dealing with ill-returned travellers from malaria-endemic regions and who need to decide on subsequent oral anti-malarial treatment or timely referral to a specialized centre for high-level monitoring and intensified parenteral treatment
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