9,005 research outputs found

    Performance of a centrifugal pump running in inverse mode

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    This paper presents the functional characterization of a centrifugal pump used as a turbine. It shows the characteristics of the machine involved at several rotational speeds, comparing the respective flows and heads. In this way, it is possible to observe the influence of the rotational speed on efficiency, as well as obtaining the characteristics at constant head and runaway speed. Also, the forces actuating on the impeller were studied. An uncertainty analysis was made to assess the accuracy of the results. The research results indicate that the turbine characteristics can be predicted to some extent from the pump characteristics, that water flows out of the runner free of swirl flow at the best efficiency point, and that radial stresses are lower than in pump mode

    Developing the evidence base for adult social care practice: The NIHR School for Social Care Research

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    In a foreword to 'Shaping the Future of Care Together', Prime Minister Gordon Brown says that a care and support system reflecting the needs of our times and meeting our rising aspirations is achievable, but 'only if we are prepared to rise to the challenge of radical reform'. A number of initiatives will be needed to meet the challenge of improving social care for the growing older population. Before the unveiling of the green paper, The National Institute for Health Research (NIHR) announced that it has provided 15m pounds over a five-year period to establish the NIHR School for Social Care Research. The School's primary aim is to conduct or commission research that will help to improve adult social care practice in England. The School is seeking ideas for research topics, outline proposals for new studies and expert advice in developing research methods

    Considerations in the design of large space structures

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    Several analytical studies of topics relevant to the design of large space structures are presented. Topics covered are: the types and quantitative evaluation of the disturbances to which large Earth-oriented microwave reflectors would be subjected and the resulting attitude errors of such spacecraft; the influence of errors in the structural geometry of the performance of radiofrequency antennas; the effect of creasing on the flatness of tensioned reflector membrane surface; and an analysis of the statistics of damage to truss-type structures due to meteoroids

    A Broad Search for Counterrotating Gas and Stars: Evidence for Mergers and Accretion

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    We measure the frequency of bulk gas-stellar counterrotation in a sample of 67 galaxies drawn from the Nearby Field Galaxy Survey, a broadly representative survey of the local galaxy population down to M_B-15. We detect 4 counterrotators among 17 E/S0's with extended gas emission (24% +8 -6). In contrast, we find no clear examples of bulk counterrotation among 38 Sa-Sbc spirals, although one Sa does show peculiar gas kinematics. This result implies that, at 95% confidence, no more than 8% of Sa-Sbc spirals are bulk counterrotators. Among types Sc and later, we identify only one possible counterrotator, a Magellanic irregular. We use these results together with the physical properties of the counterrotators to constrain possible origins for this phenomenon.Comment: 19 pages, 4 figures, AJ, accepte

    Optimised patient information materials and recruitment to a study of behavioural activation in older adults : an embedded study within a trial [version 1; peer review: awaiting peer review]

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    YesPrinted participant information about randomised controlled trials is often long, technical and difficult to navigate. Improving information materials is possible through optimisation and user-testing, and may impact on participant understanding and rates of recruitment. Methods: A study within a trial (SWAT) was undertaken within the CASPER trial. Potential CASPER participants were randomised to receive either the standard trial information or revised information that had been optimised through information design and user testing. Results: A total of 11,531 patients were randomised in the SWAT. Rates of recruitment to the CASPER trial were 2.0% in the optimised information group and 1.9% in the standard information group (odds ratio 1.027; 95% CI 0.79 to 1.33; p=0.202). Conclusions: Participant information that had been optimised through information design and user testing did not result in any change to rate of recruitment to the host trial. Registration: ISRCTN ID ISRCTN02202951; registered on 3 June 2009.UK National Institute of Health Research Health Technology Assessment Programme (project number 08/19/04)This article is included in the Studies Within A Trial (SWAT) collection (https://f1000research.com/collections/swat

    Calculations for Mirror Symmetry with D-branes

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    We study normal functions capturing D-brane superpotentials on several one- and two-parameter Calabi-Yau hypersurfaces and complete intersections in weighted projective space. We calculate in the B-model and interpret the results using mirror symmetry in the large volume regime, albeit without identifying the precise A-model geometry in all cases. We identify new classes of extensions of Picard-Fuchs equations, as well as a novel type of topology changing phase transition involving quantum D-branes. A 4-d domain wall which is obtained in one region of closed string moduli space from wrapping a four-chain interpolating between two Lagrangian submanifolds is, for other values of the parameters, represented by a disk ending on a single Lagrangian.Comment: 42 page

    Dissolved oxygen measurments in sea water at the Woods Hole Oceanographic Institution

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    This report describes a modified Winkler titration technique that has been used for the past 25 years at the Woods Hole Oceanographic Institution (WHOI). During this time most of the dissolved oxygen measurements made at sea by WHOI personnel have been analyzed with this technique and only relatively minor, evolutionary changes in the procedures and equipment have occurred. These changes, however, have improved the precision and accuracy of deep-sea dissolved oxygen measurements to 0.005 ml/l and 0.02 ml/l respectively.Funding was provided by the National Science Foundation through grant Number OCE 87-16910

    Automated oxygen titration and salinity determination

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    This report describes a newly developed automated Winkler titration system for dissolved oxygen in seawater which is presently in use at the Woods Hole Oceanographic Institution. This amperometric, calculated, endpoint system was compared with two different automated and one manual Winkler method during a recent cruise. The four different methods agreed to within about 0.04 ml/l. The system described here measures the titrant needed to reach the endpoint with a resolution better than 0.001 ml. The standard deviation of replicate samples is 0.005 ml/l and the accuracy is about 0.02 ml/l. A technique to automatically acquire conductivity ration measurements and calculate salinity using a Guildline Autosal Salinometer is also described.Funding was provided by the National Science Foundation through Grant No. OCE88-22542

    Arithmetic Spacetime Geometry from String Theory

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    An arithmetic framework to string compactification is described. The approach is exemplified by formulating a strategy that allows to construct geometric compactifications from exactly solvable theories at c=3c=3. It is shown that the conformal field theoretic characters can be derived from the geometry of spacetime, and that the geometry is uniquely determined by the two-dimensional field theory on the world sheet. The modular forms that appear in these constructions admit complex multiplication, and allow an interpretation as generalized McKay-Thompson series associated to the Mathieu and Conway groups. This leads to a string motivated notion of arithmetic moonshine.Comment: 36 page
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