3,833 research outputs found

    netgwas: An R Package for Network-Based Genome-Wide Association Studies

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    Graphical models are powerful tools for modeling and making statistical inferences regarding complex associations among variables in multivariate data. In this paper we introduce the R package netgwas, which is designed based on undirected graphical models to accomplish three important and interrelated goals in genetics: constructing linkage map, reconstructing linkage disequilibrium (LD) networks from multi-loci genotype data, and detecting high-dimensional genotype-phenotype networks. The netgwas package deals with species with any chromosome copy number in a unified way, unlike other software. It implements recent improvements in both linkage map construction (Behrouzi and Wit, 2018), and reconstructing conditional independence network for non-Gaussian continuous data, discrete data, and mixed discrete-and-continuous data (Behrouzi and Wit, 2017). Such datasets routinely occur in genetics and genomics such as genotype data, and genotype-phenotype data. We demonstrate the value of our package functionality by applying it to various multivariate example datasets taken from the literature. We show, in particular, that our package allows a more realistic analysis of data, as it adjusts for the effect of all other variables while performing pairwise associations. This feature controls for spurious associations between variables that can arise from classical multiple testing approach. This paper includes a brief overview of the statistical methods which have been implemented in the package. The main body of the paper explains how to use the package. The package uses a parallelization strategy on multi-core processors to speed-up computations for large datasets. In addition, it contains several functions for simulation and visualization. The netgwas package is freely available at https://cran.r-project.org/web/packages/netgwasComment: 32 pages, 9 figures; due to the limitation "The abstract field cannot be longer than 1,920 characters", the abstract appearing here is slightly shorter than that in the PDF fil

    An empirical investigation of the role of camaraderie, cause, competency, and participation motives in the development of attachment to a charity sport event

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    This paper examines the factors that contribute to the meaning participants hold for charity sport events. Specifically, the paper investigates the role of three value-laden constructs; along with participation motives, to understand participant attachment to a charity sport event. An online questionnaire was given to participants in the Lance Armstrong Foundation (LAF) LIVESTRONG Challenge (n=568) following the event. Data analysis revealed two recreational event motives, three motives for charitable giving, and three value-laden constructs contribute to attachment to the charity sport event. In addition, the results revealed the value-laden constructs make a stronger contribution to event attachment than the participation motives. Suggestions are made for increasing the meaning held for the event through community building, calls to action, and customization.Griffith Business School, Department of Tourism, Sport and Hotel ManagementFull Tex

    An asymptotic induced numerical method for the convection-diffusion-reaction equation

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    A parallel algorithm for the efficient solution of a time dependent reaction convection diffusion equation with small parameter on the diffusion term is presented. The method is based on a domain decomposition that is dictated by singular perturbation analysis. The analysis is used to determine regions where certain reduced equations may be solved in place of the full equation. Parallelism is evident at two levels. Domain decomposition provides parallelism at the highest level, and within each domain there is ample opportunity to exploit parallelism. Run time results demonstrate the viability of the method

    Annabella australiensis gen. & sp. nov. (Helotiales, Cordieritidaceae) from South Australian mangroves

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    A new genus of helotialean fungi, Annabella gen. nov. (Cordieritidaceae), is described to accommodate Annabella australiensis sp. nov. This species was collected on attached decaying wood of Avicennia marina, a common mangrove species found in protected waters of southern Australia. Annabella is distinctive among Cordieritidaceae in having relatively small perithecioid hyaline to yellowish apothecia and by the absence of an ionomidotic reaction. The apothecial shape and size of Annabella is most similar to Skyttea. The molecular phylogenetic analysis of a concatenated dataset of three ribosomal nuclear loci confirms the placement of Annabella within Cordieritidaceae, as a sister clade to Skyttea

    From Loop Groups to 2-Groups

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    We describe an interesting relation between Lie 2-algebras, the Kac-Moody central extensions of loop groups, and the group String(n). A Lie 2-algebra is a categorified version of a Lie algebra where the Jacobi identity holds up to a natural isomorphism called the "Jacobiator". Similarly, a Lie 2-group is a categorified version of a Lie group. If G is a simply-connected compact simple Lie group, there is a 1-parameter family of Lie 2-algebras g_k each having Lie(G) as its Lie algebra of objects, but with a Jacobiator built from the canonical 3-form on G. There appears to be no Lie 2-group having g_k as its Lie 2-algebra, except when k = 0. Here, however, we construct for integral k an infinite-dimensional Lie 2-group whose Lie 2-algebra is equivalent to g_k. The objects of this 2-group are based paths in G, while the automorphisms of any object form the level-k Kac-Moody central extension of the loop group of G. This 2-group is closely related to the kth power of the canonical gerbe over G. Its nerve gives a topological group that is an extension of G by K(Z,2). When k = +-1, this topological group can also be obtained by killing the third homotopy group of G. Thus, when G = Spin(n), it is none other than String(n).Comment: 40 page

    Optimal Taxation in Theory and Practice

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    We highlight and explain eight lessons from optimal tax theory and compare them to the last few decades of OECD tax policy. As recommended by theory, top marginal income tax rates have declined, marginal income tax schedules have flattened, redistribution has risen with income inequality, and commodity taxes are more uniform and are typically assessed on final goods. However, trends in capital taxation are mixed, and capital income tax rates remain well above the zero level recommended by theory. Moreover, some of theory's more subtle prescriptions, such as taxes that involve personal characteristics, asset-testing, and history-dependence, remain rare in practice. Where large gaps between theory and policy remain, the difficult question is whether policymakers need to learn more from theorists, or the other way around.
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