1,355 research outputs found

    Measurement of the derivative 'ZW' for an oscillating aerofoil

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    This report presents the results of experimental measurements of the damping derivative coefficient zw for constant chord rigid wings of various aspect ratios having sweepback angles of zero and 450. The results for the rectangular wings Flow substantial agreement with the unsteady aerofoil theory developed by TI.P. Jones $2) The dependence of Zvi upon frequency parameter is as given by theory and is much less than for two dimensional flow, but the numerical results are approximately 10 per cent below the theoretical. This is attributed to the large trailing edge angle 22° of the N.A.C.A. 0020 section used for the model aerofoils. The effect of sweepback is to decrease the numerical value of z , but this effect is much less pronounced, for low than for high aspect ratios. For aspect ratios 5 and 3 the numerical value is greater than would be given by a factor of proportionality equal to the cosine of the angle of sweepback. The measurements were corrected for tunnel interference by a method based on the theoretical work of 7.P.Jones.(1

    Igneous Rock Associations in Canada 3. Large Igneous Provinces (LIPs) in Canada and Adjacent Regions: 3 Ga to Present

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    Earth history is punctuated by numerous periods during which large volumes of mafic magma were emplaced. Such magmas not generated by a 'normal' spreading ridge or by subduction are termed Large Igneous Provinces (LIPs), and consist of continental flood basalts, volcanic rifted margins, oceanic plateaus, ocean basin flood basalts, submarine ridges, and seamount chains. Associated felsic rocks may also be present. LIPs of Mesozoic and Cenozoic age are typically the best preserved. Those of Paleozoic and Proterozoic age are usually more deeply eroded, and consist of flood basalt remnants and a deep-level plumbing system (of giant dyke swarms, sill provinces and layered intrusions). In the Archean the most promising LIP candidates are greenstone belts containing komatiites. Many LIPs have been linked to regional-scale uplift, continental rifting and breakup, and climatic crises. They can be used as precisely dated time markers in the stratigraphic record, and are key targets for Ni-Cu-PGE exploration. LIPs have also become a focus in the debate on the existence and nature of mantle plumes. Canada has a rich record of LIPs. At least 80 candidates are recognized in Canada and adjacent regions, with ages ranging from 3100 to 17 Ma. We review proposed links between the LIP record of Canada and mantle plumes, continental breakup, regional uplift, and ore deposits. However, given that many mafic units in Canada remain poorly characterized, a concerted geochronology campaign with integrated paleomagnetism and geochemistry would be invaluable in expanding the application of the Canadian LIP record to solving major geological problems. RÉSUMÉ L'histoire de la Terre est ponctuĂ©e de nombreuses pĂ©riodes de mise en place de forts volumes de magma mafiques. De tels magmas qui ne sont pas issus de zones d'expansion « normale » ou de subduction sont appelĂ©s Grandes provinces ignĂ©es (GPI), et celles-ci sont constituĂ©es de basaltes d'Ă©panchements continentaux, de marges de fosse volcaniques, de plateaux ocĂ©aniques, d'Ă©panchements de basaltes de bassins ocĂ©aniques, de crĂȘtes sous-marines, et de chaĂźnes de monts sous-marines. Peuvent Ă©galement y ĂȘtre associĂ©es des suites de roches felsiques. GĂ©nĂ©ralement, les GPI du MĂ©sozoĂŻque et du CĂ©nozoĂŻque sont les mieux prĂ©servĂ©es. Celles du ProtĂ©rozoĂŻque et du PalĂ©ozoĂŻque sont gĂ©nĂ©ralement plus fortement Ă©rodĂ©es et sont constituĂ©es de vestiges de basaltes d'Ă©panchement et des rĂ©seaux de conduits d'origine (rĂ©seaux gĂ©ants de dykes, provinces de filons-couches et d'intrusifs stratifiĂ©es). Dans l'ArchĂ©en, les meilleurs candidats sont reprĂ©sentĂ©s par les bandes de roches vertes Ă  komatiites. De nombreuses GPI ont Ă©tĂ© associĂ©es Ă  des Ă©pisodes de soulĂšvement rĂ©gionaux, de dĂ©rives ou de fragmentations continentales, ainsi qu'Ă  des crises climatiques. Elles peuvent servir de marqueurs temporels stratigraphiques et sont des cibles de premiĂšre importance dans l'exploration de gisements de Cu-Ni-ÉGP. Les GPI sont aussi devenues des arguments trĂšs considĂ©rĂ©s dans le dĂ©bat sur l'existence et la nature des panaches mantelliques. Le Canada possĂšde de riches archives de GPI, et au moins 80 candidatures ont Ă©tĂ© isolĂ©es sur le territoire canadien et dans les rĂ©gions adjacentes, leur Ăąge dĂ©limitant une fourchette allant de 3 100 Ma Ă  17 Ma. Nous passons en revue les liens proposĂ©s entre la suite des GDI canadiennes d'une part, et celle des panaches mantelliques, des fragmentations continentales, des soulĂšvements rĂ©gionaux, et des gisements minĂ©raux, d'autre part. Toutefois, vu le piĂštre Ă©tat de caractĂ©risation des unitĂ©s mafiques au Canada, une campagne de caractĂ©risation gĂ©ochronologique, palĂ©omagnĂ©tique et gĂ©ochimique serait d'une valeur inestimable pour favoriser l'utilisation des GDI canadiennes pour nous aider Ă  solutionner de grands problĂšmes gĂ©ologiques

    What difference does ("good") HRM make?

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    The importance of human resources management (HRM) to the success or failure of health system performance has, until recently, been generally overlooked. In recent years it has been increasingly recognised that getting HR policy and management "right" has to be at the core of any sustainable solution to health system performance. In comparison to the evidence base on health care reform-related issues of health system finance and appropriate purchaser/provider incentive structures, there is very limited information on the HRM dimension or its impact. Despite the limited, but growing, evidence base on the impact of HRM on organisational performance in other sectors, there have been relatively few attempts to assess the implications of this evidence for the health sector. This paper examines this broader evidence base on HRM in other sectors and examines some of the underlying issues related to "good" HRM in the health sector. The paper considers how human resource management (HRM) has been defined and evaluated in other sectors. Essentially there are two sub-themes: how have HRM interventions been defined? and how have the effects of these interventions been measured in order to identify which interventions are most effective? In other words, what is "good" HRM? The paper argues that it is not only the organisational context that differentiates the health sector from many other sectors, in terms of HRM. Many of the measures of organisational performance are also unique. "Performance" in the health sector can be fully assessed only by means of indicators that are sector-specific. These can focus on measures of clinical activity or workload (e.g. staff per occupied bed, or patient acuity measures), on measures of output (e.g. number of patients treated) or, less frequently, on measures of outcome (e.g. mortality rates or rate of post-surgery complications). The paper also stresses the need for a "fit" between the HRM approach and the organisational characteristics, context and priorities, and for recognition that so-called "bundles" of linked and coordinated HRM interventions will be more likely to achieve sustained improvements in organisational performance than single or uncoordinated interventions

    An approach to classifying human resources constraints to attaining health-related Millennium Development Goals

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    BACKGROUND: For any wide-ranging effort to scale up health-related priority interventions, human resources for health (HRH) are likely to be a key to success. This study explores constraints related to human resources in the health sector for achieving the Millennium Development Goals (MDGs) in low-income countries. METHODS AND FRAMEWORK: The analysis drew on information from a variety of publicly-available sources and principally on data presented in published papers in peer-reviewed journals. For classifying HRH constraints an analytical framework was used that considers constraints at five levels: individual characteristics, the health service delivery level, the health sector level, training capacities and the sociopolitical and economic context of a country. RESULTS AND DISCUSSION: At individual level, the decision to enter, remain and serve in the health sector workforce is influenced by a series of social, economic, cultural and gender-related determinants. For example, to cover the health needs of the poorest it is necessary to employ personnel with specific social, ethnic and cultural characteristics. At health-service level, the commitment of health staff is determined by a number of organizational and management factors. The workplace environment has a great impact not only on health worker performance, but also on the comprehensiveness and efficiency of health service delivery. At health-sector level, the use of monetary and nonmonetary incentives is of crucial importance for having the accurate skill mix at the appropriate place. Scaling up of priority interventions is likely to require significant investments in initial and continuous training. Given the lead time required to produce new health workers, such investments must occur in the early phases of scaling up. At the same time coherent national HRH policies are required for giving direction on HRH development and linking HRH into health-sector reform issues, the scaling-up of priority interventions, poverty reduction strategies, and training approaches. Multisectoral collaboration and the sociopolitical and economic context of a country determine health sector workforce development and potential emigration. CONCLUSIONS: Key determinants of success for achieving international development goals are closely related to human-resource development

    Reviewing The Benefits of Health Workforce Stability

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    This paper examines the issue of workforce stability and turnover in the context of policy attempts to improve retention of health workers. The paper argues that there are significant benefits to supporting policy makers and managers to develop a broader perspective of workforce stability and methods of monitoring it. The objective of the paper is to contribute to developing a better understanding of workforce stability as a major aspect of the overall policy goal of improved retention of health workers. The paper examines some of the limited research on the complex interaction between staff turnover and organisational performance or quality of care in the health sector, provides details and examples of the measurement of staff turnover and stability, and illustrates an approach to costing staff turnover. The paper concludes by advocating that these types of assessment can be valuable to managers and policy makers as they examine which policies may be effective in improving stability and retention, by reducing turnover. They can also be used as part of advocacy for the use of new retention measures. The very action of setting up a local working group to assess the costs of turnover can in itself give managers and staff a greater insight into the negative impacts of turnover, and can encourage them to work together to identify and implement stability measures

    The clustering of physical health conditions and associations with co-occurring mental health problems and problematic alcohol use: a cross-sectional study

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    Background There is strong evidence for the co-occurrence of mental health conditions and alcohol problems, yet physical health outcomes among this group are not well characterised. This study aimed to identify clusters of physical health conditions and their associations with mental health and problematic alcohol use in England’s general population. Methods Cross-sectional analysis of the 2014 Adult Psychiatric Morbidity Survey (N = 7546) was conducted. The survey used standardised measures of problematic alcohol use and mental health conditions, including the Alcohol Use Disorders Identification Test (AUDIT) and the Clinical Interview Schedule-Revised. Participants self-reported any lifetime physical health conditions. Latent class analysis considered 12 common physical illnesses to identify clusters of multimorbidity. Multinomial logistic regression (adjusting for age, gender, ethnicity, education, and occupational grade) was used to explore associations between mental health, hazardous drinking (AUDIT 8 +), and co-occurring physical illnesses. Results Five clusters were identified with statistically distinct and clinically meaningful disease patterns: ‘Physically Healthy’ (76.62%), ‘Emerging Multimorbidity’ (3.12%), ‘Hypertension & Arthritis’ (14.28%), ‘Digestive & Bowel Problems’’ (3.17%), and ‘Complex Multimorbidity’ (2.8%). Having a mental health problem was associated with increased odds of ‘Digestive & Bowel Problems’ (adjusted multinomial odds ratio (AMOR) = 1.58; 95% CI [1.15–2.17]) and ‘Complex Multimorbidity’ (AMOR = 2.02; 95% CI [1.49–2.74]). Individuals with co-occurring mental health conditions and problematic alcohol use also had higher odds of ‘Digestive & Bowel Problems’ (AMOR = 2.64; 95% CI [1.68–4.15]) and ‘Complex Multimorbidity’ (AMOR = 2.62; 95% CI [1.61–4.23]). Conclusions Individuals with a mental health condition concurrent with problematic alcohol use experience a greater burden of physical illnesses, highlighting the need for timely treatment which is likely to include better integration of alcohol and mental health services

    A personalised smartphone-delivered just-in-time adaptive intervention (JITABug) to increase physical activity in older adults: Feasibility pilot study (Preprint)

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    Background: Just-in-time adaptive interventions (JITAIs) provide real time in-the-moment behavior change support to people when they need it most. JITAIs could be a viable way to provide personalized physical activity (PA) support to older adults in the community. However, it is unclear how feasible it is to remotely deliver a PA intervention through a smartphone to older adults or how acceptable they would find a JITAI targeting PA in everyday life. Objective: The aims of this study are to describe the development of JitaBug, a personalized smartphone-delivered JITAI designed to support older adults to increase or maintain their PA level, assess the feasibility of conducting an effectiveness trial of the JitaBug intervention, and explore the acceptability of JitaBug among older adults in a free-living setting. Methods: The intervention was developed using the Behavior Change Wheel and consisted of a wearable activity tracker (Fitbit) and a companion smartphone app (JitaBug) that delivered goal-setting, planning, reminders, and JITAI messages to encourage achievement of personalized PA goals. Message delivery was tailored based on time of day, real time PA tracker data, and weather conditions. We tested the feasibility of remotely delivering the intervention with older adults in a 6-week trial. Data collection involved assessment of PA through accelerometery and activity tracker, self-reported mood and mental well-being through ecological momentary assessment, and contextual information on PA through voice memos. Feasibility outcomes included recruitment capability and adherence to the intervention, intervention delivery in the wild, appropriateness of data collection methodology, adverse events, and participant satisfaction. Results: Of the 46 recruited older adults (aged 56-72 years), 31 (67%) completed the intervention. The intervention was successfully delivered as intended; 87% (27/31) of the participants completed the intervention independently; 94% (2247/2390) of the PA messages were successfully delivered; 99% (2239/2261) of the Fitbit and 100% (2261/2261) of the weather data calls were successful. Valid and usable wrist-worn accelerometer data were obtained from 90% (28/31) of the participants at baseline and follow-up. On average, the participants recorded 50% (7.9/16, SD 7.3) of the voice memos, 38% (3.3/8, SD 4.2) of the mood assessments, and 50% (2.1/4, SD 1.6) of the well-being assessments through the app. Overall acceptability of the intervention was very good (23/30, 77% expressed satisfaction). Participant feedback suggested that more diverse and tailored PA messages, app use reminders, technical refinements, and an improved user interface could improve the intervention and make it more appealing. Conclusions: This study suggests that a smartphone-delivered JITAI is an acceptable way to support PA in older adults in the community. Overall, the intervention is feasible; however, based on user feedback, the JitaBug app requires further technical refinements that may enhance use, engagement, and user satisfaction before moving to effectiveness trials

    An Inflaton Mass Problem in String Inflation from Threshold Corrections to Volume Stabilization

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    Inflationary models whose vacuum energy arises from a D-term are believed not to suffer from the supergravity eta problem of F-term inflation. That is, D-term models have the desirable property that the inflaton mass can naturally remain much smaller than the Hubble scale. We observe that this advantage is lost in models based on string compactifications whose volume is stabilized by a nonperturbative superpotential: the F-term energy associated with volume stabilization causes the eta problem to reappear. Moreover, any shift symmetries introduced to protect the inflaton mass will typically be lifted by threshold corrections to the volume-stabilizing superpotential. Using threshold corrections computed by Berg, Haack, and Kors, we illustrate this point in the example of the D3-D7 inflationary model, and conclude that inflation is possible, but only for fine-tuned values of the stabilized moduli. More generally, we conclude that inflationary models in stable string compactifications, even D-term models with shift symmetries, will require a certain amount of fine-tuning to avoid this new contribution to the eta problem.Comment: 25 page
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