828 research outputs found

    Thermal Conductivity of Thermally-Isolating Polymeric and Composite Structural Support Materials Between 0.3 and 4 K

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    We present measurements of the low-temperature thermal conductivity of a number of polymeric and composite materials from 0.3 to 4 K. The materials measured are Vespel SP-1, Vespel SP-22, unfilled PEEK, 30% carbon fiber-filled PEEK, 30% glass-filled PEEK, carbon fiber Graphlite composite rod, Torlon 4301, G-10/FR-4 fiberglass, pultruded fiberglass composite, Macor ceramic, and graphite rod. These materials have moderate to high elastic moduli making them useful for thermally-isolating structural supports.Comment: Accepted for publication in the journal Cryogenic

    Further results on non-diagonal Bianchi type III vacuum metrics

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    We present the derivation, for these vacuum metrics, of the Painlev\'e VI equation first obtained by Christodoulakis and Terzis, from the field equations for both minkowskian and euclidean signatures. This allows a complete discussion and the precise connection with some old results due to Kinnersley. The hyperk\"ahler metrics are shown to belong to the Multi-Centre class and for the cases exhibiting an integrable geodesic flow the relevant Killing tensors are given. We conclude by the proof that for the Bianchi B family, excluding type III, there are no hyperk\"ahler metrics.Comment: 21 pages, no figure

    Top 10 health care ethics challenges facing the public: views of Toronto bioethicists

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    BACKGROUND: There are numerous ethical challenges that can impact patients and families in the health care setting. This paper reports on the results of a study conducted with a panel of clinical bioethicists in Toronto, Ontario, Canada, the purpose of which was to identify the top ethical challenges facing patients and their families in health care. A modified Delphi study was conducted with twelve clinical bioethicist members of the Clinical Ethics Group of the University of Toronto Joint Centre for Bioethics. The panel was asked the question, what do you think are the top ten ethical challenges that Canadians may face in health care? The panel was asked to rank the top ten ethical challenges throughout the Delphi process and consensus was reached after three rounds. DISCUSSION: The top challenge ranked by the group was disagreement between patients/families and health care professionals about treatment decisions. The second highest ranked challenge was waiting lists. The third ranked challenge was access to needed resources for the aged, chronically ill, and mentally ill. SUMMARY: Although many of the challenges listed by the panel have received significant public attention, there has been very little attention paid to the top ranked challenge. We propose several steps that can be taken to help address this key challenge

    Cost-effectiveness of district-wide seasonal malaria chemoprevention when implemented through routine malaria control programme in Kita, Mali using fixed point distribution

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    Background Seasonal malaria chemoprevention (SMC) is a strategy for malaria control recommended by the World Health Organization (WHO) since 2012 for Sahelian countries. The Mali National Malaria Control Programme adopted a plan for pilot implementation and nationwide scale-up by 2016. Given that SMC is a relatively new approach, there is an urgent need to assess the costs and cost effectiveness of SMC when implemented through the routine health system to inform decisions on resource allocation. Methods Cost data were collected from pilot implementation of SMC in Kita district, which targeted 77,497 children aged 3–59 months. Starting in August 2014, SMC was delivered by fixed point distribution in villages with the first dose observed each month. Treatment consisted of sulfadoxine-pyrimethamine and amodiaquine once a month for four consecutive months, or rounds. Economic and financial costs were collected from the provider perspective using an ingredients approach. Effectiveness estimates were based upon a published mathematical transmission model calibrated to local epidemiology, rainfall patterns and scale-up of interventions. Incremental cost effectiveness ratios were calculated for the cost per malaria episode averted, cost per disability adjusted life years (DALYs) averted, and cost per death averted. Results The total economic cost of the intervention in the district of Kita was US 357,494.Drugcostsandpersonnelcostsaccountedfor34357,494. Drug costs and personnel costs accounted for 34% and 31%, respectively. Incentives (payment other than salary for efforts beyond routine activities) accounted for 25% of total implementation costs. Average financial and economic unit costs per child per round were US 0.73 and US 0.86,respectively;totalannualfinancialandeconomiccostsperchildreceivingSMCwereUS0.86, respectively; total annual financial and economic costs per child receiving SMC were US 2.92 and US 3.43,respectively.Accountingforcoverage,theeconomiccostperchildfullyadherent(receivingallfourrounds)wasUS3.43, respectively. Accounting for coverage, the economic cost per child fully adherent (receiving all four rounds) was US 6.38 and US 4.69,ifweightedhighlyadherent,(receiving3or4roundsofSMC).Whencostswerecombinedwithmodelledeffects,theeconomiccostpermalariaepisodeavertedinchildrenwasUS4.69, if weighted highly adherent, (receiving 3 or 4 rounds of SMC). When costs were combined with modelled effects, the economic cost per malaria episode averted in children was US 4.26 (uncertainty bound 2.83–7.17), US 144(135–153)perDALYavertedandUS144 (135–153) per DALY averted and US 14,503 (13,604–15,402) per death averted. Conclusions When implemented at fixed point distribution through the routine health system in Mali, SMC was highly cost-effective. As in previous SMC implementation studies, financial incentives were a large cost component

    The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance

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    The all sky surveys done by the Palomar Observatory Schmidt, the European Southern Observatory Schmidt, and the United Kingdom Schmidt, the InfraRed Astronomical Satellite and the 2 Micron All Sky Survey have proven to be extremely useful tools for astronomy with value that lasts for decades. The Wide-field Infrared Survey Explorer is mapping the whole sky following its launch on 14 December 2009. WISE began surveying the sky on 14 Jan 2010 and completed its first full coverage of the sky on July 17. The survey will continue to cover the sky a second time until the cryogen is exhausted (anticipated in November 2010). WISE is achieving 5 sigma point source sensitivities better than 0.08, 0.11, 1 and 6 mJy in unconfused regions on the ecliptic in bands centered at wavelengths of 3.4, 4.6, 12 and 22 microns. Sensitivity improves toward the ecliptic poles due to denser coverage and lower zodiacal background. The angular resolution is 6.1, 6.4, 6.5 and 12.0 arc-seconds at 3.4, 4.6, 12 and 22 microns, and the astrometric precision for high SNR sources is better than 0.15 arc-seconds.Comment: 22 pages with 19 included figures. Updated to better match the accepted version in the A

    How can smoking cessation be induced before surgery? A systematic review and meta-analysis of behaviour change techniques and other intervention characteristics

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    Background: Smokers who continue to smoke up to the point of surgery are at increased risk of a range of complications during and following surgery. Objective: To identify whether behavioural and/or pharmacological interventions increase the likelihood that smokers quit prior to elective surgery and which intervention components are associated with larger effects. Design: Systematic review with meta-analysis. Data Sources: MEDLINE, Embase and Embase Classic, CINAHL, CENTRAL. Study Selection: Studies testing the effect of smoking reduction interventions delivered at least 24 hours before elective surgery were included. Study appraisal and synthesis: Potential studies were independently screened by two people. Data relating to study characteristics and risk of bias were extracted. The effects of the interventions on pre-operative smoking abstinence were estimated using random effects meta-analyses. The association between specific intervention components (behaviour change techniques; mode; duration; number of sessions; interventionist) and smoking cessation effect sizes were estimated using meta-regressions. Results: Twenty-two studies comprising 2992 smokers were included and 19 studies were meta-analysed. Interventions increased the proportion of smokers who were abstinent or reduced smoking by surgery relative to control: g = 0.56, 95% CI 0.32 - 0.80, with rates nearly double in the intervention (46.2%) relative to the control (24.5%). Interventions that comprised more sessions, delivered face-to-face and by nurses, as well as specific behaviour change techniques (providing information on consequence of smoking/cessation; providing information on withdrawal symptoms; goal setting; review of goals; regular monitoring by others; and giving options for additional or later support) were associated with larger effects. Conclusion: Rates of smoking can be halved prior to surgery and a number of intervention characteristics can increase these effects. There was, however, some indication of publication bias meaning the benefits of such interventions may be smaller than estimated

    Interventions for treating depression after stroke

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    Background: Depression is an important consequence of stroke that impacts on recovery yet is often not detected or inadequately treated. This is an update of a Cochrane review first published in 2004. Objectives: To determine whether pharmaceutical, psychological, or electroconvulsive treatment (ECT) of depression in patients with stroke can improve outcome. Search strategy: We searched the trials registers of the Cochrane Stroke Group (last searched October 2007) and the Cochrane Depression Anxiety and Neurosis Group (last searched February 2008). In addition, we searched the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 1, 2008), MEDLINE (1966 to May 2006), EMBASE (1980 to May 2006), CINAHL (1982 to May 2006), PsycINFO (1967 to May 2006) and other databases. We also searched reference lists, clinical trials registers, conference proceedings and dissertation abstracts, and contacted authors, researchers and pharmaceutical companies. Selection criteria: Randomised controlled trials comparing pharmaceutical agents with placebo, or various forms of psychotherapy or ECT with standard care (or attention control), in patients with stroke, with the intention of treating depression. Data collection and analysis: Two review authors selected trials for inclusion and assessed methodological quality; three review authors extracted, cross-checked and entered data. Primary analyses were the prevalence of diagnosable depressive disorder at the end of treatment. Secondary outcomes included depression scores on standard scales, physical function, death, recurrent stroke and adverse effects. Main results: Sixteen trials (17 interventions), with 1655 participants, were included in the review. Data were available for 13 pharmaceutical agents, and four trials of psychotherapy. There were no trials of ECT. The analyses were complicated by the lack of standardised diagnostic and outcome criteria, and differing analytic methods. There was some evidence of benefit of pharmacotherapy in terms of a complete remission of depression and a reduction (improvement) in scores on depression rating scales, but there was also evidence of an associated increase in adverse events. There was no evidence of benefit of psychotherapy. Authors' conclusions: A small but significant effect of pharmacotherapy (not psychotherapy) on treating depression and reducing depressive symptoms was found, as was a significant increase in adverse events. More research is required before recommendations can be made about the routine use of such treatments

    The Wide-Field Infrared Survey Explorer (WISE): Mission Description and Initial On-Orbit Performance

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    The all sky surveys done by the Palomar Observatory Schmidt, the European Southern Observatory Schmidt, and the United Kingdom Schmidt, the InfraRed Astronomical Satellite and the 2 Micron All Sky Survey have proven to be extremely useful tools for astronomy with value that lasts for decades. The Wide-field Infrared Survey Explorer is mapping the whole sky following its launch on 14 December 2009. WISE began surveying the sky on 14 Jan 2010 and completed its first full coverage of the sky on July 17. The survey will continue to cover the sky a second time until the cryogen is exhausted (anticipated in November 2010). WISE is achieving 5 sigma point source sensitivities better than 0.08, 0.11, 1 and 6 mJy in unconfused regions on the ecliptic in bands centered at wavelengths of 3.4, 4.6, 12 and 22 micrometers. Sensitivity improves toward the ecliptic poles due to denser coverage and lower zodiacal background. The angular resolution is 6.1", 6.4", 6.5" and 12.0" at 3.4, 4.6, 12 and 22 micrometers, and the astrometric precision for high SNR sources is better than 0.15"

    The Major Surface-Associated Saccharides of Klebsiella pneumoniae Contribute to Host Cell Association

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    Analysing the pathogenic mechanisms of a bacterium requires an understanding of the composition of the bacterial cell surface. The bacterial surface provides the first barrier against innate immune mechanisms as well as mediating attachment to cells/surfaces to resist clearance. We utilised a series of Klebsiella pneumoniae mutants in which the two major polysaccharide layers, capsule and lipopolysaccharide (LPS), were absent or truncated, to investigate the ability of these layers to protect against innate immune mechanisms and to associate with eukaryotic cells. The capsule alone was found to be essential for resistance to complement mediated killing while both capsule and LPS were involved in cell-association, albeit through different mechanisms. The capsule impeded cell-association while the LPS saccharides increased cell-association in a non-specific manner. The electrohydrodynamic characteristics of the strains suggested the differing interaction of each bacterial strain with eukaryotic cells could be partly explained by the charge density displayed by the outermost polysaccharide layer. This highlights the importance of considering not only specific adhesin:ligand interactions commonly studied in adherence assays but also the initial non-specific interactions governed largely by the electrostatic interaction forces

    Short-Term Exercise Training Inconsistently Influences Basel Testosterone in Older Men: A Systematic Review and Meta-Analysis

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    Background The age-associated decrease in testosterone is one mechanism suggested to accelerate the aging process in males. Therefore, approaches to increase endogenous testosterone may be of benefit. The aim of this paper was to undertake a Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA)-accordant meta-analysis concerning the effect of exercise on total (TT), bioavailable (bio-T), free (free-T), and salivary (sal-T) testosterone in older males. Methods Databases were searched up to and including 20th February 2018 for the terms ‘testosterone AND exercise AND aging AND males’, ‘testosterone AND exercise AND old AND males’, ‘testosterone AND training AND aging AND males’ and ‘testosterone AND training AND old AND males’. From 1259 originally identified titles, 22 studies (randomized controlled trials; RCTs; n=9, and uncontrolled trials; UCTs; n=13) were included which had a training component, participants ≥60 years of age, and salivary or serum testosterone as an outcome measure. Meta-analyses were conducted on change to testosterone following training using standardised difference in means (SDM) and random effects models. Results The overall SDM for endurance training, resistance training, and interval training was 0.398 (95% CI = 0.034 – 0.761; P = 0.010), -0.003 (95% CI = -0.330 – 0.324; P = 0.986), and 0.283 (95% CI = 0.030 – 0.535; P = 0.028) respectively. Resistance training exhibited a qualitative effect of hormone fraction whereby free-T resulted in the greatest SDM (0.253; 95% CI = -0.043 – 0.549; P = 0.094), followed by TT (0.028; 95% CI = -0.204 – 0.260; P = 0.813), and resistance training negatively influenced bio-T (-0.373; 95% CI = -0.789 – 0.042; P = 0.078). Due to the small number of studies, subgroup analysis was not possible for endurance training and interval training studies. Conclusions Data from the present investigation suggests that resistance training does not significantly influence basal testosterone in older men. Magnitude of effect was influenced by hormone fraction, even within the same investigation. Aerobic training and interval training did result in small, significant increases in basal testosterone. The magnitude of effect is small but the existing data are encouraging and may be an avenue for further research
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