5,545 research outputs found

    A broad typology of dry rainforests on the western slopes of New South Wales

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    Dry rainforests are those communities that have floristic and structural affinities to mesic rainforests and occur in parts of eastern and northern Australia where rainfall is comparatively low and often highly seasonal. The dry rainforests of the western slopes of New South Wales are poorly-understood compared to other dry rainforests in Australia, due to a lack of regional scale studies. This paper attempts to redress this by deriving a broad floristic and structural typology for this vegetation type. Phytogeographical analysis followed full floristic surveys conducted on 400 m2 plots located within dry rainforest across the western slopes of NSW. Cluster analysis and ordination of 208 plots identified six floristic groups. Unlike in some other regional studies of dry rainforest these groups were readily assigned to Webb structural types, based on leaf size classes, leaf retention classes and canopy height. Five community types were described using both floristic and structural data: 1) Ficus rubiginosa–Notelaea microcarpa notophyll vine thicket, 2) Ficus rubiginosa–Alectryon subcinereus–Notelaea microcarpa notophyll vine forest, 3) Elaeodendron australe–Notelaea microcarpa–Geijera parviflora notophyll vine thicket, 4) Notelaea microcarpa– Geijera parviflora–Ehretia membranifolia semi-evergreen vine thicket, and 5) Cadellia pentastylis low microphyll vine forest. Floristic groupings were consistent with those described by previous quantitative studies which examined smaller portions of this study area. There was also general agreement between the present analytical study and a previous intuitive classification of dry rainforest vegetation throughout the study area, but little concurrence with a continental scale floristic classification of rainforest

    On Large-Scale Graph Generation with Validation of Diverse Triangle Statistics at Edges and Vertices

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    Researchers developing implementations of distributed graph analytic algorithms require graph generators that yield graphs sharing the challenging characteristics of real-world graphs (small-world, scale-free, heavy-tailed degree distribution) with efficiently calculable ground-truth solutions to the desired output. Reproducibility for current generators used in benchmarking are somewhat lacking in this respect due to their randomness: the output of a desired graph analytic can only be compared to expected values and not exact ground truth. Nonstochastic Kronecker product graphs meet these design criteria for several graph analytics. Here we show that many flavors of triangle participation can be cheaply calculated while generating a Kronecker product graph. Given two medium-sized scale-free graphs with adjacency matrices AA and BB, their Kronecker product graph has adjacency matrix C=A⊗BC = A \otimes B. Such graphs are highly compressible: ∣E∣|{\cal E}| edges are represented in O(∣E∣1/2){\cal O}(|{\cal E}|^{1/2}) memory and can be built in a distributed setting from small data structures, making them easy to share in compressed form. Many interesting graph calculations have worst-case complexity bounds O(∣E∣p){\cal O}(|{\cal E}|^p) and often these are reduced to O(∣E∣p/2){\cal O}(|{\cal E}|^{p/2}) for Kronecker product graphs, when a Kronecker formula can be derived yielding the sought calculation on CC in terms of related calculations on AA and BB. We focus on deriving formulas for triangle participation at vertices, tC{\bf t}_C, a vector storing the number of triangles that every vertex is involved in, and triangle participation at edges, ΔC\Delta_C, a sparse matrix storing the number of triangles at every edge.Comment: 10 pages, 7 figures, IEEE IPDPS Graph Algorithms Building Block

    Mass transfer enhancement produced by laser induced cavitation

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    A microelectrode is used to measure the mass transfer perturbation and characteristics during the growth and subsequent collapse of a single bubble (which, following its initial expansion, achieved a maximum radius, Rm, of not, vert, similar500–1000 ?m). This mass transfer enhancement was associated with the forced convection, driven by bubble motion, as the result of a single cavitation event generated by a laser pulse beneath a 25 ?m diameter Au microelectrode. Evidence for bubble growth and rebound is gained from the electrochemical and acoustic measurements. This is supported with high-speed video footage of the events generated. A threshold for the formation of large cavitation bubbles in electrolyte solutions is suggested

    Graphs, Matrices, and the GraphBLAS: Seven Good Reasons

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    The analysis of graphs has become increasingly important to a wide range of applications. Graph analysis presents a number of unique challenges in the areas of (1) software complexity, (2) data complexity, (3) security, (4) mathematical complexity, (5) theoretical analysis, (6) serial performance, and (7) parallel performance. Implementing graph algorithms using matrix-based approaches provides a number of promising solutions to these challenges. The GraphBLAS standard (istc- bigdata.org/GraphBlas) is being developed to bring the potential of matrix based graph algorithms to the broadest possible audience. The GraphBLAS mathematically defines a core set of matrix-based graph operations that can be used to implement a wide class of graph algorithms in a wide range of programming environments. This paper provides an introduction to the GraphBLAS and describes how the GraphBLAS can be used to address many of the challenges associated with analysis of graphs.Comment: 10 pages; International Conference on Computational Science workshop on the Applications of Matrix Computational Methods in the Analysis of Modern Dat

    Examining the Role of Life Satisfaction and Negative Emotionality in a Social Disorganization Framework

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    At the core of the social disorganization perspective is the notion that neighborhood structural factors (i.e., socio-economic status, residential mobility, racial heterogeneity, family disruption, and urbanization) disrupt a community’s ability to self-regulate, which in turn leads to crime and delinquency. Exogenous neighborhood characteristics believed to be causally linked to crime and delinquency are consistently derived from official Census data and endogenous community characteristics are typically measured from self-reported surveys. The body of literature supporting the social disorganization explanation of criminogenic places is growing and supports the idea that neighborhood structural determinants of crime influence residents’ feelings of social capital and collective efficacy, which in turn explains variations in levels of neighborhood crime. It is unclear, however, whether individuals’ feelings of life satisfaction and/or negative emotionality mediate this dynamic
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