170 research outputs found

    Research on the swamps of Uganda

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    During the last few minutes of the air journey from London to Entebbe the observant newcomer is often mystified by what appear to be enormous grey-green rivers, some almost a mile wide, winding their way into Lake Victoria from an invisible distance in the west. These are the swamp valleys which drain some 150 miles of the gently sloping country between the wall of the Western Rift Valley and the lake. A swamp will form in any water which is sufficiently shallow and slow-moving to permit the establishment of a characteristic vegetation. This, nourished by material washed in from the surrounding land, will continue to form new growth while the older parts die and partially decompose to form a mass of waterlogged organic matter. The process is cumulative and a balance is ultimately reached between the production of organic matter and the flow of water tending to carry it away. In slow-flowing watercourses and stagnant basins the accumulation of organic matter and silt may raise the surface of the mud above the water level, thus permitting the .establishment of vegetation favouring drier conditions and finally of a covering plants resting on an accumulation of peat many feet in dept

    Complementarity in classical dynamical systems

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    The concept of complementarity, originally defined for non-commuting observables of quantum systems with states of non-vanishing dispersion, is extended to classical dynamical systems with a partitioned phase space. Interpreting partitions in terms of ensembles of epistemic states (symbols) with corresponding classical observables, it is shown that such observables are complementary to each other with respect to particular partitions unless those partitions are generating. This explains why symbolic descriptions based on an \emph{ad hoc} partition of an underlying phase space description should generally be expected to be incompatible. Related approaches with different background and different objectives are discussed.Comment: 18 pages, no figure

    Optical properties of dust

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    http://arxiv.org/abs/0808.4123Except in a few cases cosmic dust can be studied in situ or in terrestrial laboratories, essentially all of our information concerning the nature of cosmic dust depends upon its interaction with electromagnetic radiation. This chapter presents the theoretical basis for describing the optical properties of dust -- how it absorbs and scatters starlight and reradiates the absorbed energy at longer wavelengths.Partial support by a Chandra Theory program and HST Theory Programs is gratefully acknowledged

    The impact of low-frequency and rare variants on lipid levels

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    Using a genome-wide screen of 9.6 million genetic variants achieved through 1000 Genomes Project imputation in 62,166 samples, we identify association to lipid traits in 93 loci, including 79 previously identified loci with new lead SNPs and 10 new loci, 15 loci with a low-frequency lead SNP and 10 loci with a missense lead SNP, and 2 loci with an accumulation of rare variants. In six loci, SNPs with established function in lipid genetics (CELSR2, GCKR, LIPC and APOE) or candidate missense mutations with predicted damaging function (CD300LG and TM6SF2) explained the locus associations. The low-frequency variants increased the proportion of variance explained, particularly for low-density lipoprotein cholesterol and total cholesterol. Altogether, our results highlight the impact of low-frequency variants in complex traits and show that imputation offers a cost-effective alternative to resequencing

    Discovery and fine-mapping of glycaemic and obesity-related trait loci using high-density imputation

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    Reference panels from the 1000 Genomes (1000G) Project Consortium provide near complete coverage of common and low-frequency genetic variation with minor allele frequency ≥0.5% across European ancestry populations. Within the European Network for Genetic and Genomic Epidemiology (ENGAGE) Consortium, we have undertaken the first large-scale meta-analysis of genome-wide association studies (GWAS), supplemented by 1000G imputation, for four quantitative glycaemic and obesity-related traits, in up to 87,048 individuals of European ancestry. We identified two loci for body mass index (BMI) at genome-wide significance, and two for fasting glucose (FG), none of which has been previously reported in larger meta-analysis efforts to combine GWAS of European ancestry. Through conditional analysis, we also detected multiple distinct signals of association mapping to established loci for waist-hip ratio adjusted for BMI (RSPO3) and FG (GCK and G6PC2). The index variant for one association signal at the G6PC2 locus is a low-frequency coding allele, H177Y, which has recently been demonstrated to have a functional role in glucose regulation. Fine-mapping analyses revealed that the non-coding variants most likely to drive association signals at established and novel loci were enriched for overlap with enhancer elements, which for FG mapped to promoter and transcription factor binding sites in pancreatic islets, in particular. Our study demonstrates that 1000G imputation and genetic fine-mapping of common and low-frequency variant association signals at GWAS loci, integrated with genomic annotation in relevant tissues, can provide insight into the functional and regulatory mechanisms through which their effects on glycaemic and obesity-related traits are mediated

    The PHENIX Experiment at RHIC

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    The physics emphases of the PHENIX collaboration and the design and current status of the PHENIX detector are discussed. The plan of the collaboration for making the most effective use of the available luminosity in the first years of RHIC operation is also presented.Comment: 5 pages, 1 figure. Further details of the PHENIX physics program available at http://www.rhic.bnl.gov/phenix

    Discovery and Fine-Mapping of Glycaemic and Obesity-Related Trait Loci Using High-Density Imputation

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    Reference panels from the 1000 Genomes (1000G) Project Consortium provide near complete coverage of common and low-frequency genetic variation with minor allele frequency ≥0.5% across European ancestry populations. Within the European Network for Genetic and Genomic Epidemiology (ENGAGE) Consortium, we have undertaken the fi

    Exploring pathways to optimise care in malignant bowel obstruction (EPOC): Protocol for a three-phase critical realist approach to theory-led intervention development for shared decision-making

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    Introduction Malignant bowel obstruction is a distressing complication of cancer, causing pain, nausea and vomiting, and often has a poor prognosis. Severe and rapidly developing symptoms, a lack of robust clinical guidelines and the need for multidisciplinary input make treatment decision-making challenging. Sharing decision-making with people with malignant bowel obstruction and their caregivers can be difficult, and inconsistent communication creates serious deficiencies in care by amplifying patients’ distress and uncertainty. Little attention has been paid to the implicit influences on this process–for example, the role of discipline-related norms and the beliefs of decision-makers. This study will explore how these processes work and develop interventions to improve shared decision-making. Methods and analysis Exploring Pathways to Optimise Care (EPOC) is a three-phase study set within a critical realist framework: (i) realist review, to develop explanatory theory describing collaborative decision-making in the management of malignant bowel obstruction; (ii) an in-depth interview study using modified grounded theory to explore the active ingredients of this collaboration in practice settings; and (iii) the presentation to stakeholders (practitioners, patients and caregivers) of integrated results from Phase I (theory developed from the literature) and Phase II (theory developed from current practice) as a basis for intervention mapping. We aim to produce recommendations to address the challenges, and to develop a set of tools to (i) aid interaction around shared decision-making and (ii) aid interprofessional interaction around the management of this condition

    Epistemic Entanglement due to Non-Generating Partitions of Classical Dynamical Systems

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    Quantum entanglement relies on the fact that pure quantum states are dispersive and often inseparable. Since pure classical states are dispersion-free they are always separable and cannot be entangled. However, entanglement is possible for epistemic, dispersive classical states. We show how such epistemic entanglement arises for epistemic states of classical dynamical systems based on phase space partitions that are not generating. We compute epistemically entangled states for two coupled harmonic oscillators.Comment: 13 pages, no figures; International Journal of Theoretical Physics, 201

    The Green, Green Grass of Home: an archaeo-ecological approach to pastoralist settlement in central Kenya

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    © 2016 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. This paper considers the ecological residues of pastoralist occupation at the site of Maili Sita in Laikipia, central Kenya, drawing links with the archaeological record so as to contribute a fresh approach to the ephemeral settlement sites of mobile herding communities, a methodological aspect of African archaeology that remains problematic. Variations in the geochemical and micromorphological composition of soils along transects across the site are compared with vegetation distributions and satellite imagery to propose an occupation pattern not dissimilar to contemporary Cushitic-speaking groups further north. We argue that Maili Sita exemplifies the broad migratory and cultural exchange networks in place during the mid- to late second millennium AD, with pastoralist occupants who were both physically and culturally mobile.British Academy (2002-5 Funding) European Union - Marie Curie Initiatives (EXT grant 2007-11
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