1,033 research outputs found

    Detection and characterization of hydraulically active fractures in a carbonate aquifer: results from self-potential, temperature and fluid electrical conductivity logging in the Combioula hydrothermal system in the southwestern Swiss Alps

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    A geophysical and geochemical study has been conducted in a fractured carbonate aquifer located at Combioula in the southwestern Swiss Alps with the objective to detect and characterize hydraulically active fractures along a 260-m-deep borehole. Hydrochemical analyses, borehole diameter, temperature and fluid electrical conductivity logging data were integrated in order to relate electrokinetic self-potential signals to groundwater flow inside the fracture network. The results show a generally good, albeit locally variable correlation of variations of the self-potential signals with variations in temperature, fluid electrical conductivity and borehole diameter. Together with the hydrochemical evidence, which was found to be critical for the interpretation of the self-potential data, these measurements not only made it possible to detect the hydraulically active fractures but also to characterize them as zones of fluid gain or fluid loss. The results complement the available information from the corresponding litholog and illustrate the potential of electrokinetic self-potential signals in conjunction with temperature, fluid electrical conductivity and hydrochemical analyses for the characterization of fractured aquifers, and thus may offer a perspective for an effective quantitative characterization of this increasingly important class of aquifers and geothermal reservoir

    Structure of isochorismate synthase in complex with magnesium

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    The structure of the menaquinone-specific isochorismate synthase (MenF) from Escherichia coli has been refined at a resolution of 2.0 Å in complex with magnesium. The magnesium-bound structure has a well defined and organized active site which better represents the active conformation of the enzyme than the currently available structure

    Exploring the impact of pediatric short bowel syndrome on parent well‐being using a disease‐specific pilot survey

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    Background: Children with short bowel syndrome (SBS) have complex care needs, most of which are met in the home by family caregivers who may experience a range of stressors unique to this experience. Prior research suggests that parents of children with SBS have poorer health‐related quality of life than peers parenting children without health needs, but the mechanisms shaping parent outcomes are understudied. Methods: A pilot survey was developed using a community‐driven research design to measure the impact of disease‐specific items on parent‐perceived well‐being. The cross‐sectional survey, which included both closed‐ended and open‐ended items, was distributed to a convenience sample of parents of children with SBS. Quantitative and qualitative data were integrated for a mixed‐methods analysis of how individual items impacted parent well‐being. Results: Twenty parents completed the survey. Sleep interruptions, lack of support and resources, and psychological stressors and their mental health implications were more frequently reported as stressors than logistics related to caregiving (e.g., managing therapies and preparing specialized meals). Conclusion: The impact of a child\u27s SBS on parent well‐being may stem mainly from three interconnected domains: poor sleep and its consequences, lack of access to support and resources, and a range of psychological stressors that affect parent mental health. Understanding the mechanisms through which SBS shapes parent well‐being is a necessary first step for developing targeted interventions to support parents and provide family‐centered care

    Exploring the impact of pediatric short bowel syndrome on parent well‐being using a disease‐specific pilot survey

    Get PDF
    Background: Children with short bowel syndrome (SBS) have complex care needs, most of which are met in the home by family caregivers who may experience a range of stressors unique to this experience. Prior research suggests that parents of children with SBS have poorer health‐related quality of life than peers parenting children without health needs, but the mechanisms shaping parent outcomes are understudied. Methods: A pilot survey was developed using a community‐driven research design to measure the impact of disease‐specific items on parent‐perceived well‐being. The cross‐sectional survey, which included both closed‐ended and open‐ended items, was distributed to a convenience sample of parents of children with SBS. Quantitative and qualitative data were integrated for a mixed‐methods analysis of how individual items impacted parent well‐being. Results: Twenty parents completed the survey. Sleep interruptions, lack of support and resources, and psychological stressors and their mental health implications were more frequently reported as stressors than logistics related to caregiving (e.g., managing therapies and preparing specialized meals). Conclusion: The impact of a child\u27s SBS on parent well‐being may stem mainly from three interconnected domains: poor sleep and its consequences, lack of access to support and resources, and a range of psychological stressors that affect parent mental health. Understanding the mechanisms through which SBS shapes parent well‐being is a necessary first step for developing targeted interventions to support parents and provide family‐centered care

    Turbulent superfluid profiles in a counterflow channel

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    We have developed a two-dimensional model of quantised vortices in helium II moving under the influence of applied normal fluid and superfluid in a counterflow channel. We predict superfluid and vortex-line density profiles which could be experimentally tested using recently developed visualization techniques.Comment: 3 double figures, 9 page

    Flow Phase Diagram for the Helium Superfluids

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    The flow phase diagram for He II and 3^3He-B is established and discussed based on available experimental data and the theory of Volovik [JETP Letters {\bf{78}} (2003) 553]. The effective temperature - dependent but scale - independent Reynolds number Reeff=1/q=(1+αâ€Č)/αRe_{eff}=1/q=(1+\alpha')/\alpha, where α\alpha and αâ€Č\alpha' are the mutual friction parameters and the superfluid Reynolds number characterizing the circulation of the superfluid component in units of the circulation quantum are used as the dynamic parameters. In particular, the flow diagram allows identification of experimentally observed turbulent states I and II in counterflowing He II with the turbulent regimes suggested by Volovik.Comment: 2 figure

    The Computational Complexity of Generating Random Fractals

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    In this paper we examine a number of models that generate random fractals. The models are studied using the tools of computational complexity theory from the perspective of parallel computation. Diffusion limited aggregation and several widely used algorithms for equilibrating the Ising model are shown to be highly sequential; it is unlikely they can be simulated efficiently in parallel. This is in contrast to Mandelbrot percolation that can be simulated in constant parallel time. Our research helps shed light on the intrinsic complexity of these models relative to each other and to different growth processes that have been recently studied using complexity theory. In addition, the results may serve as a guide to simulation physics.Comment: 28 pages, LATEX, 8 Postscript figures available from [email protected]
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