8,704 research outputs found

    Audit in practice : surveillance for hypoglycaemia in the neonatal paediatric intensive care unit

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    Hypoglycaemia in neonates is defined as a blood glucose ≤ 2.6 mmol/1. Certain categories of babies are at particularly high risk of developing hypoglycaemia in the first few days of life, and are routinely monitored in the Neonatal Paediatric Intensive Care Unit by reagent strips using a reflectance meter. This study shows that the current glucose meter, in use in the entire Department of Health, is unreliable in the detection of hypoglycaemia in neonates, but is accurate for values of blood glucose >3 mmol/1. For this reason, laboratory blood glucose estimation should be used for screening of neonatal hypoglycaemia until such time that a more reliable technique for bedside assay of blood glucose becomes available in the Neonatal Paediatric Intensive Care Unit.peer-reviewe

    Fast computation of the Kohn-Sham susceptibility of large systems

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    For hybrid systems, such as molecules grafted onto solid surfaces, the calculation of linear response in time dependent density functional theory is slowed down by the need to calculate, in N^4 operations, the susceptibility of N non interacting Kohn-Sham reference electrons. We show how this susceptibility can be calculated N times faster within finite precision. By itself or in combination with previous methods, this should facilitate the calculation of TDDFT response and optical spectra of hybrid systems.Comment: submitted 25/1/200

    Analysis of turbulence in fog episodes

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    Many processes interact in a complex and highly non-linear way during the life cycle of fog, the turbulent transport being among them. Observations and analysis of turbulence are, then, fundamental to our understanding of the physical mechanisms involved with fog formation, evolution and dissipation. Data gathered by fast-response sonic anemometers are processed using wavelet methods in order to estimate turbulence parameters such as kinetic energy or fluxes during the successive stages of fog evolution

    A new route towards uniformly functionalized single-layer graphene

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    It is shown, by DFT calculations, that the uniform functionalization of upper layer of graphite by hydrogen or fluorine does not change essentially its bonding energy with the underlying layers, whereas the functionalization by phenyl groups decreases the bonding energy by a factor of approximately ten. This means that the functionalized monolayer in the latter case can be easily separated by mild sonication. According to our computational results, such layers can be cleaned up to pure graphene, as well as functionalized further up to 25% coverage, without essential difficulties. The energy gap within the interval from 0.5 to 3 eV can be obtained by such one-side funtionalization using different chemical species.Comment: 15 pages, 3 figures, to appear in J. Phys. D: Applied Physic

    Determination of the magnetic anisotropy axes of single-molecule magnets

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    Simple methods are presented allowing the determination of the magnetic anisotropy axes of a crystal of a single-molecule magnet (SMM). These methods are used to determine an upper bound of the easy axis tilts in a standard Mn12-Ac crystal. The values obtained in the present study are significately smaller than those reported in recent high frequency electron paramagnetic resonance (HF-EPR) studies which suggest distributions of hard-axes tilts.Comment: 10 pages, 6 figure

    Ab initio vibrations in nonequilibrium nanowires

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    We review recent results on electronic and thermal transport in two different quasi one-dimensional systems: Silicon nanowires (SiNW) and atomic gold chains. For SiNW's we compute the ballistic electronic and thermal transport properties on equal footing, allowing us to make quantitative predictions for the thermoelectric properties, while for the atomic gold chains we evaluate microscopically the damping of the vibrations, due to the coupling of the chain atoms to the modes in the bulk contacts. Both approaches are based on a combination of density-functional theory, and nonequilibrium Green's functions.Comment: 16 pages, to appear in Progress in Nonequilibrium Green's Functions IV (PNGF4), Eds. M. Bonitz and K. Baltzer, Glasgow, August 200
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