4,790 research outputs found

    Rangeland reference areas : summary of cooperative project between the Western Australian Department of Agriculture and the Environmental Protection Authority

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    The development of agriculture in south-western Australia has been characterised by the replacement of deep-rooted, perennial species of native vegetation with shallow-rooted, annual species. Except for the high rainfall areas, the native vegetation was able to intercept and transpire nearly all of the rainfall resulting in low stream flows and recharge to a groundwater system which was typically deep and restricted to the major valleys. The lack of surface or groundwater movement out of inland catchments used large quantities of cyclic salts to become stored in the regolith. Although annual crops and pastures can be high water users, they are poorly adapted to transpire rainfall outside of the growing season

    The Use of Mixed Models for the Analysis of Mediated Data with Time-Dependent Predictors

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    Linear mixed models (LMMs) are frequently used to analyze longitudinal data. Although these models can be used to evaluate mediation, they do not directly model causal pathways. Structural equation models (SEMs) are an alternative technique that allows explicit modeling of mediation. The goal of this paper is to evaluate the performance of LMMs relative to SEMs in the analysis of mediated longitudinal data with time-dependent predictors and mediators. We simulated mediated longitudinal data from an SEM and specified delayed effects of the predictor. A variety of model specifications were assessed, and the LMMs and SEMs were evaluated with respect to bias, coverage probability, power, and Type I error. Models evaluated in the simulation were also applied to data from an observational cohort of HIV-infected individuals. We found that when carefully constructed, the LMM adequately models mediated exposure effects that change over time in the presence of mediation, even when the data arise from an SEM

    Estimating Heterogeneous Intra-class Correlation Coefficients in Dyadic Ecological Momentary Assessment

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    A method is described for estimating and testing predictors for influence on the variance of momentary behaviors in dyadic ecological momentary assessment data. Results show that the method allows intraclass correlations of momentary observations from two members of the same couple to vary by observation-level, individual-level and couple-level predictors

    Genome Analysis: Birds of a Feather

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    This Birds-of-a-Feather session presents the national infrastructure serving genome science, including NCGAS, iPlant, XSEDE, and networks, detailing goals, resources, and projects.This research is supported by NSF Award 1062432 – ABI Development: National Center for Genome Analysis Support (NCGAS).  This research was also supported by a generous grant from the Lilly Endowment, Inc. to the Indiana University Pervasive Technology Institute

    Profiling of berries by comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GCxGC/TOF-MS)

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    poster C149, Proceedings Annual Biomedical Research Conference for Minority Students (ABRCMS 2011), November 9 - 12, 2011, America’s Center, St. Louis, MO, US
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