2,342 research outputs found

    Voyager Interstellar Mission (VIM)

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    The DSN (Deep Space Network) mission support requirements for the Voyager Interstellar Mission (VIM) are summarized. The general objectives of the VIM are to investigate the interplanetary and interstellar media and to continue the Voyager program of ultraviolet astronomy. The VIM will utilize both Voyager spacecraft for the period from January 1990 through December 2019. The mission objectives are outlined and the DSN support requirements are defined through the presentation of tables and narratives describing the spacecraft flight profile; DSN support coverage; frequency assignments; support parameters for telemetry, control and support systems; and tracking support responsibility

    First-principles calculation of mechanical properties of Si <001> nanowires and comparison to nanomechanical theory

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    We report the results of first-principles density functional theory calculations of the Young's modulus and other mechanical properties of hydrogen-passivated Si nanowires. The nanowires are taken to have predominantly {100} surfaces, with small {110} facets according to the Wulff shape. The Young's modulus, the equilibrium length and the constrained residual stress of a series of prismatic beams of differing sizes are found to have size dependences that scale like the surface area to volume ratio for all but the smallest beam. The results are compared with a continuum model and the results of classical atomistic calculations based on an empirical potential. We attribute the size dependence to specific physical structures and interactions. In particular, the hydrogen interactions on the surface and the charge density variations within the beam are quantified and used both to parameterize the continuum model and to account for the discrepancies between the two models and the first-principles results.Comment: 14 pages, 10 figure

    Ingot Hard Red Spring Wheat

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    This bulletin provides a brief overview of Ingot Hard Red Spring Wheat. Information regarding its origin, disease resistance, and other traits is provided

    Oxen Hard Red Spring Wheat

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    This bulletin provides a brief overview of Oxen Hard Red Spring Wheat. Information regarding its origin, disease resistance, and other traits is provided

    Nucleation and Growth of GaN/AlN Quantum Dots

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    We study the nucleation of GaN islands grown by plasma-assisted molecular-beam epitaxy on AlN(0001) in a Stranski-Krastanov mode. In particular, we assess the variation of their height and density as a function of GaN coverage. We show that the GaN growth passes four stages: initially, the growth is layer-by-layer; subsequently, two-dimensional precursor islands form, which transform into genuine three-dimensional islands. During the latter stage, island height and density increase with GaN coverage until the density saturates. During further GaN growth, the density remains constant and a bimodal height distribution appears. The variation of island height and density as a function of substrate temperature is discussed in the framework of an equilibrium model for Stranski-Krastanov growth.Comment: Submitted to PRB, 10 pages, 15 figure

    Deficiencies in education and experience in the management of acute kidney injury among Malawian healthcare workers

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    Background Acute kidney injury (AKI) is a common but under-recognised disease process, which carries a high risk of mortality or chronic complications, such as chronic kidney disease and other organ dysfunction. Management of AKI, however, is suboptimal, both in developed settings and in Malawi. This is partly because of deficiencies in AKI education and training.Aim To establish current levels of AKI education in a range of healthcare workers in Malawi.Methods An AKI symposium was held in Blantyre in March 2015. Delegates were asked to complete a survey at the start of the symposium to assess their clinical experience and education in the management of AKI.Results From 100 delegates, 89 nurses, clinical officers, and physicians, originating from 11 different districts, responded to the survey. Twenty-two percent of healthcare workers (including 28% of district workers of the various cadres and 31% of nurses) had never received teaching on any aspect of renal disease, and 50% (including 63% of district workers and 61% of nurses) had never received teaching specifically on AKI. Forty-four percent did not feel confident managing AKI, and 98% wanted more support managing patients with renal disease. Thirty-four percent (including 55% of district workers) were unaware that haemodialysis was available at Queen Elizabeth Central Hospital (QECH) for the treatment of AKI and 53% (74% of district workers) were unaware that peritoneal dialysis was available for the treatment of AKI in children. Only 33% had ever referred a patient with AKI to QECH.Conclusions There are deficiencies in education about, and clinical experience in, the management of AKI among Malawian healthcare workers, in addition to limited awareness of the renal service available at QECH. Urgent action is required to address these issues in order to prevent morbidity and mortality from AKI in Malawi

    Dynamic of a non homogeneously coarse grained system

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    To study materials phenomena simultaneously at various length scales, descriptions in which matter can be coarse grained to arbitrary levels, are necessary. Attempts to do this in the static regime (i.e. zero temperature) have already been developed. In this letter, we present an approach that leads to a dynamics for such coarse-grained models. This allows us to obtain temperature-dependent and transport properties. Renormalization group theory is used to create new local potentials model between nodes, within the approximation of local thermodynamical equilibrium. Assuming that these potentials give an averaged description of node dynamics, we calculate thermal and mechanical properties. If this method can be sufficiently generalized it may form the basis of a Molecular Dynamics method with time and spatial coarse-graining.Comment: 4 pages, 4 figure

    Forge: A New Hard Red Spring Wheat

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    Just as pieces of iron can be heated and hammered into something new and different, plant breeders can forge new varieties by recombining the DNA of existing plants. Forge hard red spring wheat is an example of this powerful technique. Parents of Forge are Butte 86, Guard, and Sharp. Although Forge shares characteristics with each of its parents, it is a unique cultivar. The South Dakota Agricultural Experimental Station released Foundation seed of Forge in the spring of 1997. Certified seed is available for the 1999 season. Application for Plant Variety Protection has been made, and Forge will be sold only as a class of certified seed (Foundation, Registered, or Certified)

    Russ Hard Red Winter Wheat

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    This bulletin provides a brief overview of Russ Hard Red Spring Wheat. Information regarding its origin, disease resistance, and other traits is provided

    The potential for circular dichroism as an additional facile and sensitive method of monitoring low-molecular-weight heparins and heparinoids

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    The ultraviolet circular dichroism (CD) spectra of commercial low-molecular-weight heparins, heparinoids and other anticoagulant preparations have been recorded between 180 and 260 nm. Principal component analysis of the spectra allowed their differentiation into a number of groups related to the means of their production reflecting the structural changes introduced by each process. The findings suggest that CD provides a complementary technique for the rapid analysis of heparin preparations
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