18,647 research outputs found

    Nanocrystal seeding: A low temperature route to polycrystalline Si films

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    A novel method is presented for growth of polycrystalline silicon films on amorphous substrates at temperatures of 540–575 °C. Grain nucleation and grain growth are performed in two steps, using Si nanocrystals as nuclei ("seeds"). The nanocrystal seeds are produced by excimer laser photolysis of disilane in a room temperature flow cell. Film (grain) growth occurs epitaxially on the seeds in a separate thermal chemical vapor deposition (CVD) step, with growth rates 10–100 times higher than similar CVD growth rates on crystal Si. Grain size and CVD growth rates are dependent on seed coverage, for seed coverage <0.2 monolayers

    Integrated care and the working record

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    By default, many discussions and specifications of electronic health records or integrated care records often conceptualize the record as a passive information repository. This article presents data from a case study of work in a medical unit in a major metropolitan hospital. It shows how the clinicians tailored, re-presented and augmented clinical information to support their own roles in the delivery of care for individual patients. This is referred to as the working record: a set of complexly interrelated clinician-centred documents that are locally evolved, maintained and used to support delivery of care in conjunction with the more patient-centred chart that will be stored in the medical records department on the patient’s discharge. Implications are drawn for how an integrated care record could support the local tailorability and flexibility that underpin this working record and hence underpin practice

    Mixed Linear Layouts of Planar Graphs

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    A kk-stack (respectively, kk-queue) layout of a graph consists of a total order of the vertices, and a partition of the edges into kk sets of non-crossing (non-nested) edges with respect to the vertex ordering. In 1992, Heath and Rosenberg conjectured that every planar graph admits a mixed 11-stack 11-queue layout in which every edge is assigned to a stack or to a queue that use a common vertex ordering. We disprove this conjecture by providing a planar graph that does not have such a mixed layout. In addition, we study mixed layouts of graph subdivisions, and show that every planar graph has a mixed subdivision with one division vertex per edge.Comment: Appears in the Proceedings of the 25th International Symposium on Graph Drawing and Network Visualization (GD 2017

    Upward Point-Set Embeddability

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    We study the problem of Upward Point-Set Embeddability, that is the problem of deciding whether a given upward planar digraph DD has an upward planar embedding into a point set SS. We show that any switch tree admits an upward planar straight-line embedding into any convex point set. For the class of kk-switch trees, that is a generalization of switch trees (according to this definition a switch tree is a 11-switch tree), we show that not every kk-switch tree admits an upward planar straight-line embedding into any convex point set, for any k2k \geq 2. Finally we show that the problem of Upward Point-Set Embeddability is NP-complete

    Cross-cultural comparison of genetic and cultural transmission of smoking initiation using an extended twin kinship model

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    Background: Considerable evidence from twin and adoption studies indicates that genetic and shared environmental factors play a role in the initiation of smoking behavior. Although twin and adoption designs are powerful to detect genetic and environmental influences, they do not provide information on the processes of assortative mating and parent–offspring transmission and their contribution to the variability explained by genetic and/or environmental factors. Methods: We examined the role of genetic and environmental factors in individual differences for smoking initiation (SI) using an extended kinship design. This design allows the simultaneous testing of additive and non-additive genetic, shared and individual-specific environmental factors, as well as sex differences in the expression of genes and environment in the presence of assortative mating and combined genetic and cultural transmission, while also estimating the regression of the prevalence of SI on age. A dichotomous lifetime ‘ever’ smoking measure was obtained from twins and relatives in the ‘Virginia 30,000’ sample and the ‘Australian 25,000’. Results: Results demonstrate that both genetic and environmental factors play a significant role in the liability to SI. Major influences on individual differences appeared to be additive genetic and unique environmental effects, with smaller contributions from assortative mating, shared sibling environment, twin environment, cultural transmission, and resulting genotype-environment covariance. Age regression of the prevalence of SI was significant. The finding of negative cultural transmission without dominance led us to investigate more closely two possible mechanisms for the lower parent–offspring correlations compared to the sibling and DZ twin correlations in subsets of the data: (1) age × gene interaction, and (2) social homogamy. Neither of the mechanism provided a significantly better explanation of the data. Conclusions: This study showed significant heritability, partly due to assortment, and significant effects of primarily non-parental shared environment on liability to SI

    Table of Contents and Prologue

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    Editorial board, Table of contents, and Prologue, an introduction to volume 1

    Beyond policy and planning to practice: getting sexual health on the agenda in Aboriginal communities in Western Australia

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    Background: Indigenous Australians have significantly poorer status on a large range of health,educational and socioeconomic measures and successive Australian governments at state andfederal level have committed to redressing these disparities. Despite this, improvements inAboriginal health status have been modest, and Australia has much greater disparities in the healthof its Indigenous people compared to countries that share a history characterised by colonisationand the dispossession of indigenous populations such as New Zealand, Canada and the UnitedStates of America. Efforts at policy and planning must ultimately be translated into practicalstrategies. This article outlines an approach that was effective in Western Australia in increasingthe engagement and concern of Aboriginal people about high rates of sexually transmissibleinfections and sexual health issues. Many aspects of the approach are relevant for other healthissues. Results: The complexity of Indigenous sexual health necessitates inter-agency and crossgovernmental collaboration, in addition to Aboriginal leadership, accurate data, and communitysupport. A recent approach covering all these areas is described. This has resulted in Aboriginalsexual health being more actively discussed within Aboriginal health settings than it once was andadditional resources for Indigenous sexual health being available, with better communication andpartnership across different health service providers and sectors. The valuable lessons in capacitybuilding, collaboration and community engagement are readily transferable to other health issues, and may be useful for other health professionals working in the challenging area of Aboriginal health.Conclusion: Health service planners and providers grapple with achieving Aboriginal ownershipand leadership regarding their particular health issue, despite sincere concern and commitment toaddressing Aboriginal health issues. This highlights the need to secure genuine Aboriginalengagement. Building capacity that enables Indigenous people and communities to fulfill their owngoals is a long-term strategy and requires sustained commitment, but we argue is a prerequisite for better Indigenous health outcomes

    Upward Three-Dimensional Grid Drawings of Graphs

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    A \emph{three-dimensional grid drawing} of a graph is a placement of the vertices at distinct points with integer coordinates, such that the straight line segments representing the edges do not cross. Our aim is to produce three-dimensional grid drawings with small bounding box volume. We prove that every nn-vertex graph with bounded degeneracy has a three-dimensional grid drawing with O(n3/2)O(n^{3/2}) volume. This is the broadest class of graphs admiting such drawings. A three-dimensional grid drawing of a directed graph is \emph{upward} if every arc points up in the z-direction. We prove that every directed acyclic graph has an upward three-dimensional grid drawing with (n3)(n^3) volume, which is tight for the complete dag. The previous best upper bound was O(n4)O(n^4). Our main result is that every cc-colourable directed acyclic graph (cc constant) has an upward three-dimensional grid drawing with O(n2)O(n^2) volume. This result matches the bound in the undirected case, and improves the best known bound from O(n3)O(n^3) for many classes of directed acyclic graphs, including planar, series parallel, and outerplanar

    Kondo regime in triangular arrangements of quantum dots: Molecular orbitals, interference and contact effects

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    Transport properties of an interacting triple quantum dot system coupled to three leads in a triangular geometry has been studied in the Kondo regime. Applying mean-field finite-U slave boson and embedded cluster approximations to the calculation of transport properties unveils a set of rich features associated to the high symmetry of this system. Results using both calculation techniques yield excellent overall agreement and provide additional insights into the physical behavior of this interesting geometry. In the case when just two current leads are connected to the three-dot system, interference effects between degenerate molecular orbitals are found to strongly affect the overall conductance. An S=1 Kondo effect is also shown to appear for the perfect equilateral triangle symmetry. The introduction of a third current lead results in an `amplitude leakage' phenomenon, akin to that appearing in beam splitters, which alters the interference effects and the overall conductance through the system.Comment: 14 pages, 9 figures, submitted to PR
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