932 research outputs found

    Large Parameter Cases of the Gauss Hypergeometric Function

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    We consider the asymptotic behaviour of the Gauss hypergeometric function when several of the parameters a, b, c are large. We indicate which cases are of interest for orthogonal polynomials (Jacobi, but also Krawtchouk, Meixner, etc.), which results are already available and which cases need more attention. We also consider a few examples of 3F2-functions of unit argument, to explain which difficulties arise in these cases, when standard integrals or differential equations are not available.Comment: 21 pages, 4 figure

    Operational framework for rural hospitals during a pandemic

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    It is now evident that a second wave of the COVID-19 pandemic has developed. The unfortunate reality is that those in rural areas may be impacted the hardest. Ethical decision making may look the same for rural areas as urban areas, but this is far from accurate. This practice article is focused on why the challenges are different and how rural hospitals might manage their unique circumstances and constraints. A step-wise decision-making framework is also proposed

    Alpha, Betti and the Megaparsec Universe: on the Topology of the Cosmic Web

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    We study the topology of the Megaparsec Cosmic Web in terms of the scale-dependent Betti numbers, which formalize the topological information content of the cosmic mass distribution. While the Betti numbers do not fully quantify topology, they extend the information beyond conventional cosmological studies of topology in terms of genus and Euler characteristic. The richer information content of Betti numbers goes along the availability of fast algorithms to compute them. For continuous density fields, we determine the scale-dependence of Betti numbers by invoking the cosmologically familiar filtration of sublevel or superlevel sets defined by density thresholds. For the discrete galaxy distribution, however, the analysis is based on the alpha shapes of the particles. These simplicial complexes constitute an ordered sequence of nested subsets of the Delaunay tessellation, a filtration defined by the scale parameter, α\alpha. As they are homotopy equivalent to the sublevel sets of the distance field, they are an excellent tool for assessing the topological structure of a discrete point distribution. In order to develop an intuitive understanding for the behavior of Betti numbers as a function of α\alpha, and their relation to the morphological patterns in the Cosmic Web, we first study them within the context of simple heuristic Voronoi clustering models. Subsequently, we address the topology of structures emerging in the standard LCDM scenario and in cosmological scenarios with alternative dark energy content. The evolution and scale-dependence of the Betti numbers is shown to reflect the hierarchical evolution of the Cosmic Web and yields a promising measure of cosmological parameters. We also discuss the expected Betti numbers as a function of the density threshold for superlevel sets of a Gaussian random field.Comment: 42 pages, 14 figure

    Solvent content of protein crystals from diffraction intensities by Independent Component Analysis

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    An analysis of the protein content of several crystal forms of proteins has been performed. We apply a new numerical technique, the Independent Component Analysis (ICA), to determine the volume fraction of the asymmetric unit occupied by the protein. This technique requires only the crystallographic data of structure factors as input.Comment: 9 pages, 2 figures, 1 tabl

    Understanding Energy Consumption at Work

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    A practical approach to hospital visitation during a pandemic: Responding with compassion to unjustified restrictions

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    During the COVID-19 pandemic, evidence-based resources have been sought to support decision-making and strategically inform hospitals’ policies, procedures, and practices. While greatly emphasizing protection, most guiding documents have neglected to support and protect the psychosocial needs of frontline health care workers and patients and their families during provision of palliative and end-oflife care. Consequently, the stage has been set for increased anxiety, moral distress, and moral injury and extreme moral hazard. A family-centered approach to care has been unilaterally relinquished to a secondary and nonessential role during the current crisis. This phenomenon violates a foundational public health principle, namely, to apply the least restrictive means to achieve good for the many. Instead, there has been widespread adoption of utilitarian and paternalistic approaches. In many cases the foundational principles of palliative care have also been neglected. No circumstance, even a global public health emergency, should ever cause health care providers to deny their ethical obligations and human commitment to compassion. The lack of responsive protocols for family visitation, particularly at the end of life, is an important gap in the current recommendations for pandemic triage and contingency planning. A stepwise approach to hospital visitation using a tiered, standardized process for responding to emerging clinical circumstances and individual patients’ needs should be considered, following the principle of proportionality

    Challenges of and opportunities for protecting European soil biodiversity

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    Soil biodiversity and related ecosystem functions are neglected in most biodiversity assessments and nature conservation actions. We examined how society, and particularly policy makers, have addressed these factors worldwide with a focus on Europe and explored the role of soils in nature conservation in Germany as an example. We reviewed past and current global and European policies, compared soil ecosystem functioning in- and outside protected areas, and examined the role of soils in nature conservation management via text analyses. Protection and conservation of soil biodiversity and soil ecosystem functioning have been insufficient. Soil-related policies are unenforceable and lack soil biodiversity conservation goals, focusing instead on other environmental objectives. We found no evidence of positive effects of current nature conservation measures in multiple soil ecosystem functions in Europe. In German conservation management, soils are considered only from a limited perspective (e.g., as physicochemical part of the environment and as habitat for aboveground organisms). By exploring policy, evidence, and management as it relates to soil ecosystems, we suggest an integrative perspective to move nature conservation toward targeting soil ecosystems directly (e.g., by setting baselines, monitoring soil threats, and establishing a soil indicator system)

    ABA triblock copolymers: from controlled synthesis to controlled function

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    The ABA amphiphilic block copolymers, poly(hydroxyethyl methacrylate-hlock-methylphenylsilane-block-hydroxyethyl methacrylate) (PHEMA-PMPS-PHEMA) and poly[oligo(ethylene glycol) methyl ether methacrylate-block-methylphenylsilane-block-oligo(ethylene glycol). methyl ether methacrylate] (POEGMA-PMPS-POEGMA) were successfully synthesised via atom transfer radical polymerisation (ATRP). Macroinitiators suitable for the ATRP of oligo(ethylene glycol) methyl ether methacrylate and 2-hydroxyethyl methacrylate were synthesised from the condensation reaction of alpha,omega-dihalopolymethylphenylsilane and 2'-hydroxyethyl 2-bromo-2-methylpropanoate. The copolymers were characterised using H-1 NMR and C-13 NMR spectroscopy and molecular weight characteristics were determined using size exclusion chromatography and H-1 NMR. The aggregation behaviour of some of the copolymers in water was studied using transmission and scanning electron microscopy and dynamic light scattering. These revealed the prevalent aggregate species to be micelles. Larger aggregates of 300-1000 nm diameter were also observed. The UV induced degradation of the aggregates was studied by UV-Vis spectroscopy. The thermal behaviour of selected copolymers was studied by differential scanning calorimetry and microphase separation of the two components was demonstrated
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