33,542 research outputs found

    Evidence of Two Distinct Dynamic Critical Exponents in Connection with Vortex Physics

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    The dynamic critical exponent zz is determined from numerical simulations for the three-dimensional (3D) lattice Coulomb gas (LCG) and the 3D XY models with relaxational dynamics. It is suggested that the dynamics is characterized by two distinct dynamic critical indices z0z_0 and zz related to the divergence of the relaxation time τ\tau by τξz0\tau\propto \xi^{z_0} and τkz\tau\propto k^{-z}, where ξ\xi is the correlation length and kk the wavevector. The values determined are z01.5z_0\approx 1.5 and z1z\approx 1 for the 3D LCG and z01.5z_0\approx 1.5 and z2z\approx 2 for the 3D XY model. It is argued that the nonlinear IVIV exponent relates to z0z_0, whereas the usual Hohenberg-Halperin classification relates to zz. Possible implications for the interpretation of experiments are pointed out. Comparisons with other existing results are discussed.Comment: to appear in PR

    Confirmation of the Electrostatic Self-Assembly of Nanodiamonds

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    A reliable explanation for the underlying mechanism responsible for the persistent aggregation and self-assembly of colloidal 5 nm diamond nanoparticles is critical to the development of nanodiamond-based technologies. Although a number of mechanisms have been proposed, validation has been hindered by the inherent difficulty associated with the identification and characterisation of the inter-particle interfaces. In this paper we present results of high resolution aberration corrected electron microscopy and complementary computer simulations to explicate the features involved, and confirm the electrostatic interaction mechanism as the most probable cause for the formation of agglutinates and agglomerates of primary particles.Comment: 9 pages (including Supplementary Information), accepted for publication by Nanoscal

    Country planning for health interventions under development: lessons from the malaria vaccine decision-making framework and implications for other new interventions

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    Traditionally it has taken years or decades for new public health interventions targeting diseases found in developing countries to be accessible to those most in need. One reason for the delay has been insufficient anticipation of the eventual processes and evidence required for decision making by countries. This paper describes research into the anticipated processes and data needed to inform decision making on malaria vaccines, the most advanced of which is still in phase 3 trials. From 2006 to 2008, a series of country consultations in Africa led to the development of a guide to assist countries in preparing their malaria vaccine decision-making frameworks. The guide builds upon the World Health Organization’s Vaccine Introduction Guidelines. It identifies the processes and data for decisions, when they would be needed relative to the development timelines of the intervention, and where they will come from. Policy development will be supported by data (e.g. malaria disease burden; roles of other malaria interventions; malaria vaccine impact; economic and financial issues; malaria vaccine efficacy, quality and safety) as will implementation decisions (e.g. programmatic issues and socio-cultural environment). This generic guide can now be applied to any future malaria vaccine. The paper discusses the opportunities and challenges to early planning for country decision-making—from the potential for timely, evidence-informed decisions to the risks of over-promising around an intervention still under development. Careful and well-structured planning by countries is an important way to ensure that new interventions do not remain unused for years or decades after they become available

    Evaluation of the efficacy of Alpron disinfectant for dental unit water lines

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    AIMS: To assess the efficacy of a disinfectant, Alpron, for controlling microbial contamination within dental unit water lines. METHODS: The microbiological quality of water emerging from the triple syringe, high speed handpiece, cup filler and surgery hand wash basin from six dental units was assessed for microbiological total viable counts at 22 degrees C and 37 degrees C before and after treatment with Alpron solutions. RESULTS: The study found that the use of Alpron disinfectant solutions could reduce microbial counts in dental unit water lines to similar levels for drinking water. This effect was maintained in all units for up to six weeks following one course of treatment. In four out of six units the low microbial counts were maintained for 13 weeks. CONCLUSIONS: Disinfectants may have a short term role to play in controlling microbial contamination of dental unit water lines to drinking water quality. However, in the longer term attention must be paid to redesigning dental units to discourage the build up of microbial biofilms

    Report on the Findings of the 2004 Australian National eProcurement Survey

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    This report highlights the key findings from the 2004 Australian National eProcurement Survey. The aim of the 2004 Australian National eProcurement Survey is to establish the nature, extent and adoption profile of eProcurement strategies and processes of Australian organisations.Australian Research Council (Grant No. LP0214841

    Report on the Findings of the 2004 Australian National eProcurement Survey

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    This report highlights the key findings from the 2004 Australian National eProcurement Survey. The aim of the 2004 Australian National eProcurement Survey is to establish the nature, extent and adoption profile of eProcurement strategies and processes of Australian organisations.Australian Research Council (Grant No. LP0214841

    Spiral shocks and the formation of molecular clouds in a two phase medium

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    We extend recent numerical results (Dobbs et. al. 2006) on molecular cloud formation in spiral galaxies by including a multi-phase medium. The addition of a hot phase of gas enhances the structure in the cold gas, and significantly increases the fraction of molecular hydrogen that is formed when the cold gas passes through a spiral shock. The difference in structure is reflected in the mass power spectrum of the molecular clouds, which is steeper for the multi-phase calculations. The increase in molecular gas occurs as the addition of a hot phase leads to higher densities in the cold gas. In particular, cold gas is confined in clumps between the spiral arms and retains a higher molecular fraction. Unlike the single phase results, molecular clouds are present in the inter-arm regions for the multi-phase medium. However the density of the inter-arm molecular hydrogen is generally below that which can be reliably determined from CO measurements. We therefore predict that for a multi-phase medium, there will be low density clouds containing cold atomic and molecular hydrogen, which are potentially entering the spiral arms.Comment: 11 pages, 14 figures, accepted for publication in MNRA
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