652 research outputs found

    Empirical scaling of antisymmetric stratified wakes

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    Proceedings of the "Bluff Body Wakes and Vortex-Induced Vibrations - BBVIV-4"Initially turbulent wakes of a propelled cylinder at nonzero angles of yaw to the mean flow were measured in the horizontal centerplane plane up to approximately 100 buoyancy times, where vertical velocities are very small. The profiles of mean velocity were found to be antisymmetric throughout their lifetime, with both width and maximum velocity decaying at the same rate as previously studied momentum wakes. The maximum velocity of the profile is proportional to the angle of yaw, but the width is constant. Both the mean flow and fluctuating quantities show that the late wake is self-similar, with scaling laws that are consistent with previous work on propelled and drag wakes

    Thermal expansion of rare earth metals

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    A high temperature dilatometric investigation of the rare earth metals was undertaken as part of a broad program of study of these elements, the ultimate goal being better understanding of metals in general. The more immediate goal, in addition to determining the coefficients of expansion quantitatively, was to detect evidence of any crystalline transformations which may occur and particularly to cast some light on certain high temperature transitions already discovered in several of these metals. The rare earth metals included in this investigation were lanthanum, cerium, praseodymium, neodymium, gadolinium, terbium, dysprosium, erbium, and ytterbium

    The formation of volatile sulphur compounds in unclarified grape juice

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    The evolution of the sulphur gases OCS, CS2 and DMS was monitored during the clarification of freshly harvested juices from Müller-Turgau and Riesling. Immediately after crushing OCS and CS2 levels began to increase, substantially favoured by high temperatures. When fermentation started concentrations decreased. DMS was found only in fermenting juices

    Three-dimensional simulation for fast forward flight of a calliope hummingbird

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    We present a computational study of flapping-wing aerodynamics of a calliope hummingbird (Selasphorus calliope) during fast forward flight. Three-dimensional wing kinematics were incorporated into the model by extracting time-dependent wing position from high-speed videos of the bird flying in a wind tunnel at 8.3 m s−1. The advance ratio, i.e. the ratio between flight speed and average wingtip speed, is around one. An immersed-boundary method was used to simulate flow around the wings and bird body. The result shows that both downstroke and upstroke in a wingbeat cycle produce significant thrust for the bird to overcome drag on the body, and such thrust production comes at price of negative lift induced during upstroke. This feature might be shared with bats, while being distinct from insects and other birds, including closely related swifts

    Does vitamin D sufficiency equate to a single serum 25-Hydroxyvitamin D level or are different levels required for non-skeletal diseases?

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    Objective: Clarify the concept of vitamin D sufficiency, the relationship between efficacy and vitamin D status and the role of Vitamin D supplementation in the management of non-skeletal diseases. We outline reasons for anticipating different serum vitamin D levels are required for different diseases. Method: Review the literature for evidence of efficacy of supplementation and minimum effective 25-hydroxyvitamin D (25-OHD) levels in non-skeletal disease. Results: Evidence of efficacy of vitamin supplementation is graded according to levels of evidence. Minimum effective serum 25-OHD levels are lower for skeletal disease, e.g., rickets (25 nmol/L), osteoporosis and fractures (50 nmol/L), than for premature mortality (75 nmol/L) or non-skeletal diseases, e.g., depression (75 nmol/L), diabetes and cardiovascular disease (80 nmol/L), falls and respiratory infections (95 nmol/L) and cancer (100 nmol/L). Conclusions: Evidence for the efficacy of vitamin D supplementation at serum 25-OHD levels ranging from 25 to 100 nmol/L has been obtained from trials with vitamin D interventions that change vitamin D status by increasing serum 25-OHD to a level consistent with sufficiency for that disease. This evidence supports the hypothesis that just as vitamin D metabolism is tissue dependent, so the serum levels of 25-OHD signifying deficiency or sufficiency are disease dependent.Simon Spedding, Simon Vanlint, Howard Morris and Robert Scrag

    The IUPHAR Guide to Immunopharmacology: connecting immunology and pharmacology

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    Given the critical role that the immune system plays in a multitude of diseases, having a clear understanding of the pharmacology of the immune system is crucial to new drug discovery and development. Here we describe the International Union of Basic and Clinical Pharmacology (IUPHAR) Guide to Immunopharmacology (GtoImmuPdb), which connects expert-curated pharmacology with key immunological concepts and aims to put pharmacological data into the hands of immunologists. In the pursuit of new therapeutics, pharmacological databases are a vital resource to researchers through providing accurate information on the fundamental science underlying drug action. This extension to the existing IUPHAR/British Pharmacological Society Guide to Pharmacology supports research into the development of drugs targeted at modulating immune, inflammatory or infectious components of disease. To provide a deeper context for how the resource can support research we show data in GtoImmuPdb relating to a case study on the targeting of vascular inflammation

    Landscape science: a Russian geographical tradition

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    The Russian geographical tradition of landscape science (landshaftovedenie) is analyzed with particular reference to its initiator, Lev Semenovich Berg (1876-1950). The differences between prevailing Russian and Western concepts of landscape in geography are discussed, and their common origins in German geographical thought in the late nineteenth and early twentieth centuries are delineated. It is argued that the principal differences are accounted for by a number of factors, of which Russia's own distinctive tradition in environmental science deriving from the work of V. V. Dokuchaev (1846-1903), the activities of certain key individuals (such as Berg and C. O. Sauer), and the very different social and political circumstances in different parts of the world appear to be the most significant. At the same time it is noted that neither in Russia nor in the West have geographers succeeded in specifying an agreed and unproblematic understanding of landscape, or more broadly in promoting a common geographical conception of human-environment relationships. In light of such uncertainties, the latter part of the article argues for closer international links between the variant landscape traditions in geography as an important contribution to the quest for sustainability
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