501 research outputs found

    Fast global interactive volume segmentation with regional supervoxel descriptors

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    In this paper we propose a novel approach towards fast multi-class volume segmentation that exploits supervoxels in order to reduce complexity, time and memory requirements. Current methods for biomedical image segmentation typically require either complex mathematical models with slow convergence, or expensive-to-calculate image features, which makes them non-feasible for large volumes with many objects (tens to hundreds) of different classes, as is typical in modern medical and biological datasets. Recently, graphical models such as Markov Random Fields (MRF) or Conditional Random Fields (CRF) are having a huge impact in different computer vision areas (e.g. image parsing, object detection, object recognition) as they provide global regularization for multiclass problems over an energy minimization framework. These models have yet to find impact in biomedical imaging due to complexities in training and slow inference in 3D images due to the very large number of voxels. Here, we define an interactive segmentation approach over a supervoxel space by first defining novel, robust and fast regional descriptors for supervoxels. Then, a hierarchical segmentation approach is adopted by training Contextual Extremely Random Forests in a user-defined label hierarchy where the classification output of the previous layer is used as additional features to train a new classifier to refine more detailed label information. This hierarchical model yields final class likelihoods for supervoxels which are finally refined by a MRF model for 3D segmentation. Results demonstrate the effectiveness on a challenging cryo-soft X-ray tomography dataset by segmenting cell areas with only a few user scribbles as the input for our algorithm. Further results demonstrate the effectiveness of our method to fully extract different organelles from the cell volume with another few seconds of user interaction. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

    SMURFS: superpixels from multi-scale refinement of super-regions

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    Recent applications in computer vision have come to rely on superpixel segmentation as a pre-processing step for higher level vision tasks, such as object recognition, scene labelling or image segmentation. Here, we present a new algorithm, Superpixels from MUlti-scale ReFinement of Super-regions (SMURFS), which not only obtains state-of-the-art superpixels, but can also be applied hierarchically to form what we call n-th order super-regions. In essence, starting from a uniformly distributed set of super-regions, the algorithm iteratively alternates graph-based split and merge optimization schemes which yield superpixels that better represent the image. The split step is performed over the pixel grid to separate large super-regions into different smaller superpixels. The merging process, conversely, is performed over the superpixel graph to create 2nd-order super-regions (super-segments). Iterative refinement over two scale of regions allows the algorithm to achieve better over-segmentation results than current state-of-the-art methods, as experimental results show on the public Berkeley Segmentation Dataset (BSD500)

    Delayed Emergence of Trachykele blondeli blondeli (Coleoptera: Buprestidae)

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    Prolonged emergence of Trachykele blondeli blondeli Marseul (Coleoptera: Buprestidae) is reported from kiln-dried and subsequently painted wood in this report. The specimen emergence is a new record for Florida. Because the specimen did not emerge from host plant material grown in Florida, it is likely that its origin was exterior to Florida. Because of delayed and prolonged emergence capability in Buprestidae, as well as specimen survival of wood preservation processes like kiln drying, the current report does indicate a concern for redistribution of non-indigenous buprestid species to new areas

    Probing quark gluon plasma with jets

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    We study multiple scatterings of jets on constituents of quark gluon plasma and introduce energy--energy correlations to quantify their effects. The effects from a longitudinally expanding plasma on medium as well as high energy jets are found to be significant at both RHIC and LHC energies. Because jets escape from the plasma long before the completion of mixed phase, these effects are free from complications of final state hadronic interactions and decays. These suggest that jets can be used to probe the plasma that might be created in future high energy heavy ion collisions.Comment: 15 pages, 6 figures in 5 ps files included, McGill/94-1

    The Longhorned Beetles (Coleoptera: Cerambycidae) of Tennessee: Distribution of Species, Seasonal Adult Activity, and New State Records

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    Efforts to document species of longhorned beetles (Coleoptera: Cerambycidae) occurring in Tennessee have not been updated since 1973. To address this knowledge gap, institutional, research, and private collections in Tennessee were reviewed to provide faunal distribution assessments and seasonal activity data for the cerambycid beetle species active in Tennessee. Examinations of 9,918 specimens and records yielded a list of 230 cerambycid beetle species within 5 subfamilies. Twenty-seven species are reported as new state records from Tennessee. Adult seasonal activity data that were recorded on specimen labels are presented. Where available, notes on collection method, adult resources, and larval host plants are provided for species within a supplementary table. Supplemental figures report the distribution for species collected across the state and from 85 of the 95 Tennessee counties, as well as the ecoregions from which each species is reported. The bias-corrected Chao1 species richness estimator predicts another 11 species remain to be identified across the state. Future collection efforts in the Central Appalachian, Mississippi Alluvial and Valley Loess Plains, Southeastern Plains, and western portions of the Interior Plateau ecoregions could yield additional new state records. Developmental host and adult resource plants, collection methods, as well as regional collection notes from adjacent states are discussed for several additional candidate longhorned beetle species

    A Precision Calculation of the Next-to-Leading Order Energy-Energy Correlation Function

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    The O(alpha_s^2) contribution to the Energy-Energy Correlation function (EEC) of e+e- -> hadrons is calculated to high precision and the results are shown to be larger than previously reported. The consistency with the leading logarithm approximation and the accurate cancellation of infrared singularities exhibited by the new calculation suggest that it is reliable. We offer evidence that the source of the disagreement with previous results lies in the regulation of double singularities.Comment: 6 pages, uuencoded LaTeX and one eps figure appended Complete paper as PostScript file (125 kB) available at: http://www.phys.washington.edu/~clay/eecpaper1/paper.htm

    Power corrections to event shapes and factorization

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    We study power corrections to the differential thrust, heavy mass and related event shape distributions in e+ee^+e^--annihilation, whose values, ee, are proportional to jet masses in the two-jet limit, e0e\to 0. The factorization properties of these differential distributions imply that they may be written as convolutions of nonperturbative "shape" functions, describing the emission of soft quanta by the jets, and resummed perturbative cross sections. The infrared shape functions are different for different event shapes, and depend on a factorization scale, but are independent of the center-of-mass energy QQ. They organize all power corrections of the form 1/(eQ)n1/(eQ)^n, for arbitrary nn, and carry information on a class of universal matrix elements of the energy-momentum tensor in QCD, directly related to the energy-energy correlations.Comment: 15 pages, LaTeX style, 1 figure embedded with epsf.st

    Effects of Color Attributes on Trap Capture Rates of Chrysobothris femorata (Coleoptera: Buprestidae) and Related Species

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    Chrysobothris spp. (Coleoptera: Buprestidae) and other closely related buprestids are common pests of fruit, shade, and nut trees in the United States. Many Chrysobothris spp., including Chrysobothris femorata, are polyphagous herbivores. Their wide host range leads to the destruction of numerous tree species in nurseries and orchards. Although problems caused by Chrysobothris are well known, there are no reliable monitoring methods to estimate local populations before substantial damage occurs. Other buprestid populations have been effectively estimated using colored sticky traps to capture beetles. However, the attraction of Chrysobothris to specific color attributes has not been directly assessed. A multi-color trapping system was utilized to determine color attraction of Chrysobothris spp. Specific color attributes (lightness [L*], red to green [a*], blue to yellow [b*], chroma [C*], hue [h*], and peak reflectance [PR]) were then evaluated to determine beetle responses. In initial experiments with mostly primary colors, Chrysobothris were most attracted to traps with red coloration. Thus, additional experiments were performed using a range of trap colors with red reflectance values. Among these red reflectance colors, it was determined that the violet range of the electromagnetic spectrum had greater attractance to Chrysobothris. Additionally, Chrysobothris attraction correlated with hue and b*, suggesting a preference for traps with hues between red to blue. However, males and females of some Chrysobothris species showed differentiated responses. These findings provide information on visual stimulants that can be used in Chrysobothris trapping and management. Furthermore, this information can be used in conjunction with ecological theory to understand host-location methods of Chrysobothris
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