1,236 research outputs found

    Simulated breath waveform control

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    Subsystem was developed which provides twelve waveform controls to breath drive mechanism. Twelve position, magnetically actuated rotary switch is connected to one end of crankshaft drive, such that it makes one complete revolution for each simulated breath. Connections with common wired point are included in modifications made to standard motor speed controller

    Breathing-metabolic simulator

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    Breathing-metabolic simulator was developed to be used for evaluation of life support equipment. Apparatus simulates human breathing rate and controls temperature and humidity of exhaled air as well as its chemical composition. All functions are designed to correspond to various degrees of human response

    Atomic oxygen studies on polymers

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    The purpose was to study the effects of atomic oxygen on the erosion of polymer based materials. The development of an atomic oxygen neutral beam facility using a SURFATRON surface wave launcher that can produce beam energies between 2 and 3 eV at flux levels as high as approx. 10 to the 17th power atoms/cm (2)-sec is described. Thin film dielectric materials were studied to determine recession rates and and reaction efficiencies as a function of incident beam energy and fluence. Accelerated testing was also accomplished and the values of reaction efficiency compared to available space flight data. Electron microscope photomicrographs of the samples' surface morphology were compared to flight test specimens

    Drag and inertia coefficients for horizontally submerged rectangular cylinders in waves and currents

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    The results of an experimental investigation carried out to measure combined wave and current loads on horizontally submerged square and rectangular cylinders are reported in this paper. The wave and current induced forces on a section of the cylinders with breadth-depth (aspect) ratios equal to 1, 0.5, and 0.75 are measured in a wave tank. The maximum value of Keulegan-Carpenter (KC) number obtained in waves alone is about 5 and Reynolds (Re) number ranged from 6.3976103 to 1.186105. The drag (CD) and inertia (CM) coefficients for each cylinder are evaluated using measured sectional wave forces and particle kinematics calculated from linear wave theory. The values of CD and CM obtained for waves alone have already been reported (Venugopal, V., Varyani, K. S., and Barltrop, N. D. P. Wave force coefficients for horizontally submerged rectangular cylinders. Ocean Engineering, 2006, 33, 11-12, 1669-1704) and the coefficients derived in combined waves and currents are presented here. The results indicate that both drag and inertia coefficients are strongly affected by the presenceof the current and show different trends for different cylinders. The values of the vertical component inertia coefficients (CMY) in waves and currents are generally smaller than the inertia coefficients obtained in waves alone, irrespective of the current's magnitude and direction. The results also illustrate the effect of a cylinder's aspect ratio on force coefficients. This study will be useful in the design of offshore structures whose columns and caissons are rectangular sections

    Multiple ejections during the 1975 outburst of A0620-00

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    The well-known black-hole X-ray transient A0620-00 was a bright radio source during the first part of its outburst in 1975. We have revisited the available data and find for the first time evidence that the source exhibited multiple jet ejections. Rapid radio spectral changes indicate the addition of at least three new components which are initially optically thick. From single baseline interferometry taken about three weeks after the start of the X-ray outburst we find that the source is extended on arcsec scales and infer a relativistic expansion velocity. Some of the other (soft) X-ray transients, such as GS 1124-68 and GS 2000+25, show very similar X-ray outburst light curve shapes to that of A0620-00, while their radio outburst light curve shapes are different. We suggest that this is due to the radio emission being strongly beamed in outburst, whereas the X-ray emission remains isotropic. Since this effect is stronger at higher jet velocities, this strengthens our conclusion that the jets in A0620-00 and other soft X-ray transients move with relativistic speeds

    A combined microfinance and training intervention can reduce HIV risk behaviour in young female participants.

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    OBJECTIVE: To assess effects of a combined microfinance and training intervention on HIV risk behavior among young female participants in rural South Africa. DESIGN: : Secondary analysis of quantitative and qualitative data from a cluster randomized trial, the Intervention with Microfinance for AIDS and Gender Equity study. METHODS: Eight villages were pair-matched and randomly allocated to receive the intervention. At baseline and after 2 years, HIV risk behavior was assessed among female participants aged 14-35 years. Their responses were compared with women of the same age and poverty group from control villages. Intervention effects were calculated using adjusted risk ratios employing village level summaries. Qualitative data collected during the study explored participants' responses to the intervention including HIV risk behavior. RESULTS: After 2 years of follow-up, when compared with controls, young participants had higher levels of HIV-related communication (adjusted risk ratio 1.46, 95% confidence interval 1.01-2.12), were more likely to have accessed voluntary counseling and testing (adjusted risk ratio 1.64, 95% confidence interval 1.06-2.56), and less likely to have had unprotected sex at last intercourse with a nonspousal partner (adjusted risk ratio 0.76, 95% confidence interval 0.60-0.96). Qualitative data suggest a greater acceptance of intrahousehold communication about HIV and sexuality. Although women noted challenges associated with acceptance of condoms by men, increased confidence and skills associated with participation in the intervention supported their introduction in sexual relationships. CONCLUSIONS: In addition to impacts on economic well being, women's empowerment and intimate partner violence, interventions addressing the economic and social vulnerability of women may contribute to reductions in HIV risk behavior

    The Canadian Federation of Earth Sciences Scientific Statement on Climate Change – Its Impacts in Canada, and the Critical Role of Earth Scientists in Mitigation and Adaptation

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    The Canadian Federation of Earth Sciences (CFES) has issued this statement to summarize the science, effects, and implications of climate change. We highlight the role of Earth scientists in documenting and mitigating climate change, and in managing and adapting to its consequences in Canada. CFES is the coordinated voice of Canada’s Earth Sciences community with 14 member organizations representing some 15,000 geoscientists. Our members are drawn from academia, industry, education, and government. The mission of CFES is to ensure decision makers and the public understand the contributions of Earth Science to Canadian society and the economy.  Climate change has become a national and global priority for all levels of government. The geological record shows us that the global climate has changed throughout Earth’s history, but the current rates of change are almost unprecedented. Over the last 70 years, levels of common greenhouse gases (GHGs) in the atmosphere have steadily increased. Carbon dioxide (CO2) concentration is now 418 parts per million — its highest of the last three million years. The chemical (isotopic) composition of carbon in the atmosphere indicates the increase in GHGs is due to burning fossil fuels. GHGs absorb energy emitted from Earth’s surface and re-radiate it back, warming the lower levels of the atmosphere. Climatic adjustments that have recently occurred are, in practical terms, irreversible, but further change can be mitigated by lowering emissions of GHGs.  Climate change is amplified by three important Earth system processes and effects. First, as the climate warms evaporation increases, raising atmospheric concentrations of water vapour, itself a GHG — and adding to warming. Second, loss of ice cover from the polar ice sheets and glaciers exposes larger areas of land and open water — leading to greater absorption of heat from the sun. Third, thawing of near-surface permafrost releases additional GHGs (primarily CO2 and methane) during decay of organic matter previously preserved frozen in the ground. Some impacts of climate change are incremental and steadily occurring, such as melting of glaciers and ice sheets, with consequent sea level rise. Others are intermittent, such as extreme weather events, like hurricanes — but are becoming more frequent. Summer water shortages are increasingly common in western Canada as mountain snowpacks melt earlier and summer river flows decline. In northern Canada, warming and thawing of near-surface permafrost has led to deterioration of infrastructure and increased costs for buildings that now require chilled foundations. Other consequences of unchecked climate change include increased coastal erosion, increases in the number and size of wildfires, and reduction in winter road access to isolated northern communities. Reductions in net GHG emissions are urgently required to mitigate the many effects of further climate change. Industrial and public works development projects must now assess the effects of climate change in their planning, design, and management. Cities, municipalities, and rural communities need to plan new residential development carefully to avoid enhanced risk of flooding, coastal erosion, or wildfire.  Earth Science knowledge and expertise is integral to exploration and development of new metals and Earth materials required for a carbon-neutral future, and in the capture and storage of CO2 within the Earth. Earth Science is also central to society’s adaptation to new climatic regimes and reduction of risks. This includes anticipation, assessment, and management of extreme events, development of new standards and guidelines for geotechnical and engineering practice, and revision to regulations that consider climate change. Geoscientists also have an important role in the education of students and the public on the reasons for necessary action. Canada is uniquely positioned with its strong global geoscientific leadership, its vast landmass, and its northern terrain to effectively leverage research activities around climate change. Geoscience tools and geoscientists’ skills will be integral to Canada’s preparation for climate change.La Fédération canadienne des sciences de la Terre (FCST) a publié ce communiqué pour résumer la science, les effets et les implications des changements climatiques. Nous soulignons le rôle des scientifiques en science de la Terre dans la documentation et l'atténuation des changements climatiques, ainsi que dans la gestion de leurs conséquences et la création de mesures d'adaptation au Canada. La FCST est la voix coordonnée de la communauté canadienne des sciences de la Terre avec 14 organisations membres représentant environ 15 000 géoscientifiques. Nos membres sont issus du milieu universitaire, de l'industrie, de l'éducation et du gouvernement. La mission de la FCST est de s'assurer que les décideurs et le public comprennent les contributions des sciences de la Terre à la société canadienne et à l'économie.  Les changements climatiques sont devenus une priorité nationale et mondiale à tous les niveaux de gouvernement. Les archives géologiques nous montrent que le climat mondial a changé tout au long de l'histoire de la Terre, mais les taux de changement actuels sont presque sans précédent. Au cours des 70 dernières années, les niveaux de gaz à effet de serre (GES) communs dans l'atmosphère n'ont cessé d'augmenter. La concentration de dioxyde de carbone (CO2) est maintenant de 418 parties par million - son plus haut niveau des trois derniers millions d'années. La composition chimique (isotopique) du carbone dans l'atmosphère indique que l'augmentation des GES est due à la combustion de combustibles fossiles. Les GES absorbent l'énergie émise par la surface de la Terre et la réfléchissent, réchauffant les niveaux inférieurs de l'atmosphère. Les modifications climatiques qui se sont produits récemment sont, concrètement, irréversibles, mais les changements additionnels peuvent être atténués en réduisant les émissions de GES.  Les changements climatiques sont amplifiés par trois processus et effets importants du système terrestre. Premièrement, à mesure que le climat se réchauffe, l'évaporation augmente, ce qui augmente les concentrations atmosphériques de vapeur d'eau, elle-même un GES, et contribue au réchauffement. Deuxièmement, la perte de la couverture de glace des calottes glaciaires polaires et des glaciers expose de plus grandes superficies de terre et d'eau libre, ce qui entraîne une plus grande absorption de la chaleur du soleil. Troisièmement, le dégel du pergélisol proche de la surface libère des GES supplémentaires (principalement du CO2 et du méthane) lors de la décomposition de la matière organique jusqu’alors préservée gelée dans le sol. Certains impacts des changements climatiques sont progressifs et se produisent régulièrement, comme la fonte des glaciers et des calottes glaciaires, avec pour conséquence une élévation du niveau de la mer. D'autres sont intermittents, comme les événements météorologiques extrêmes, tels que les ouragans, mais deviennent de plus en plus fréquents. Les pénuries d'eau en été sont de plus en plus courantes dans l'ouest du Canada, car le manteau neigeux des montagnes fond plus tôt et le débit des rivières en été diminue. Dans le nord du Canada, le réchauffement et le dégel du pergélisol proche de la surface ont entraîné une détérioration des infrastructures et une augmentation des coûts des bâtiments qui nécessitent maintenant des fondations réfrigérées. Les autres conséquences des changements climatiques incontrôlés comprennent l'augmentation de l'érosion côtière, l'augmentation du nombre et de la taille des incendies de forêt et la réduction de l'accès aux routes d’hiver aux collectivités isolées du Nord. Des réductions des émissions nettes de GES sont nécessaires de toute urgence pour atténuer les nombreux effets de nouveaux changements climatiques. Les projets de développement industriel et de travaux publics doivent désormais évaluer les effets des changements climatiques dans leur planification, leur conception et leur gestion. Les villes, les municipalités et les communautés rurales doivent planifier soigneusement les nouveaux développements résidentiels pour éviter les risques accrus d'inondation, d'érosion côtière ou d'incendie de forêt.  Les connaissances et l'expertise en sciences de la Terre font partie intégrante de l'exploration et du développement de nouveaux métaux et matériaux terrestres requis pour un avenir neutre en carbone, ainsi que dans la capture et la séquestration du CO2 dans la Terre. Les sciences de la Terre sont également au cœur de l'adaptation de la société aux nouveaux régimes climatiques et de la réduction des risques. Cela comprend l'anticipation, l'évaluation et la gestion des événements extrêmes, l'élaboration de nouvelles normes et directives pour les pratiques géotechniques et d'ingénierie, et la révision des réglementations qui tient compte des changements climatiques. Les géoscientifiques ont également un rôle important dans l'éducation des étudiants et du public sur le fondement des mesures nécessaires. Le Canada occupe une position unique grâce à son solide leadership géoscientifique mondial, sa vaste étendue et son territoire nordique pour tirer efficacement parti des activités de recherche sur les changements climatiques. Les outils géoscientifiques et les compétences des géoscientifiques feront partie intégrante de la préparation du Canada aux changements climatiques
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