8,523 research outputs found

    The multicolored Asian lady beetle : Harmonia axyridis (Pallas, 1773) (Coleoptera: Coccinellidae) ; a not so new invasive insect in Colombia and South America

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    The first reports of the multicolored Asian lady beetle Harmonia axyridis (Pallas, 1773) (Coleoptera: Coccinellidae) in Colombia appeared in 2011. However, based on museum insect specimens, the introduction of H. axyridis in Colombia occurred in 1989 or earlier, making it the second oldest record of the species in South America after the deliberate releases of the species in Argentina in 1986. Currently in Colombia, H. axyridis is well established and is here recorded from the States of Antioquia, Caldas, Cauca, Cundinamarca, Nariño, Tolima and Valle del Cauca.Los primeros reportes de la mariquita multicolor asiática Harmonia axyridis (Pallas, 1773) (Coleoptera: Coccinellidae) aparecieron en el 2011. Sin embargo, con base en colecciones de insectos en museos, la introducción de H. axyridis en Colombia ocurrió en 1989 o antes, haciendo que este sea el segundo registro más antiguo de esta especie en Sur América, después de las liberaciones intencionales de la especie en Argentina en 1986. Actualmente en Colombia, H. axyridis está bien establecida y aquí se reporta en los departamentos de Antioquia, Caldas, Cauca, Cundinamarca, Nariño, Tolima y el Valle del Cauca

    Descriptions of the male of Heterodiomus marchali Brèthes and a new species of Chilean Heterodiomus Brèthes (Coleoptera: Coccinellidae: Scymninae: Diomini)

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    Additions to the classification of South American Diomini are provided. Male genitalia of Heterodiomus marchali Brèthes are described and Diomus brethesi is newly described

    Additions to the Hyperaspis Chevrolat (Coleoptera: Coccinellidae) fauna of South American, descriptions of nine new species, and recognition of Hyperaspis pectoralis Crotch as a valid species

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    Nine new species of Hyperaspis from various South American localities are described, illustrated, and compared with previously described taxa. New taxa are: Hyperaspis luciae, H. corcovado, H. divaricata, H. humboldti, H. mimica, H. praecipua, H. unimaculosa, H. drechseli, and H. esmeraldas. Hyperaspis pectoralis Crotch is recognized as a valid species of Hyperaspis and integrated into the existing classification

    A GPU-based Evolution Strategy for Optic Disk Detection in Retinal Images

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    La ejecución paralela de aplicaciones usando unidades de procesamiento gráfico (gpu) ha ganado gran interés en la comunidad académica en los años recientes. La computación paralela puede ser aplicada a las estrategias evolutivas para procesar individuos dentro de una población, sin embargo, las estrategias evolutivas se caracterizan por un significativo consumo de recursos computacionales al resolver problemas de gran tamaño o aquellos que se modelan mediante funciones de aptitud complejas. Este artículo describe la implementación de una estrategia evolutiva para la detección del disco óptico en imágenes de retina usando Compute Unified Device Architecture (cuda). Los resultados experimentales muestran que el tiempo de ejecución para la detección del disco óptico logra una aceleración de 5 a 7 veces, comparado con la ejecución secuencial en una cpu convencional.Parallel processing using graphic processing units (GPUs) has attracted much research interest in recent years. Parallel computation can be applied to evolution strategy (ES) for processing individuals in a population, but evolutionary strategies are time consuming to solve large computational problems or complex fitness functions. In this paper we describe the implementation of an improved ES for optic disk detection in retinal images using the Compute Unified Device Architecture (CUDA) environment. In the experimental results we show that the computational time for optic disk detection task has a speedup factor of 5x and 7x compared to an implementation on a mainstream CPU

    Rotating and counterrotating relativistic thin disks as sources of stationary electrovacuum spacetimes

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    A detailed study is presented of the counterrotating model (CRM) for electrovacuum stationary axially symmetric relativistic thin disks of infinite extension without radial stress, in the case when the eigenvalues of the energy-momentum tensor of the disk are real quantities, so that there is not heat flow. We find a general constraint over the counterrotating tangential velocities needed to cast the surface energy-momentum tensor of the disk as the superposition of two counterrotating charged dust fluids. We then show that, in some cases, this constraint can be satisfied if we take the two counterrotating tangential velocities as equal and opposite or by taking the two counterrotating streams as circulating along electro-geodesics. However, we show that, in general, it is not possible to take the two counterrotating fluids as circulating along electro-geodesics nor take the two counterrotating tangential velocities as equal and opposite. A simple family of models of counterrotating charged disks based on the Kerr-Newman solution are considered where we obtain some disks with a CRM well behaved. We also show that the disks constructed from the Kerr-Newman solution can be interpreted, for all the values of parameters, as a matter distribution with currents and purely azimuthal pressure without heat flow. The models are constructed using the well-known "displace, cut and reflect" method extended to solutions of vacuum Einstein-Maxwell equations. We obtain, in all the cases, counterrotating Kerr-Newman disks that are in agreement with all the energy conditions.Comment: 22 pages, 7 figures, Late

    First report of Delphastus quinculus Gordon and Diomus seminulus (Mulsant) (Coleoptera: Coccinellidae) feeding on eggs and first-instar nymphs of Crypticerya multicicatrices Kondo and Unruh (Hemiptera: Monophlebidae)

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    Delphastus quinculus Gordon and Diomus seminulus (Mulsant) (Coleoptera: Coccinellidae) are reported for the first time feeding on eggs and first-instar nymphs of Crypticerya multicicatrices Kondo and Unruh (Hemiptera: Monophlebidae). Diagnosis and illustrations are provided for both species. Updated information on their biology, hosts and geographical distribution is also provided.Se reportan a Delphastus quinculus Gordon y Diomus seminulus (Mulsant) (Coleoptera: Coccinellidae) por primera vez como depredadores de huevos y ninfas del primer instar de Crypticerya multicicatrices Kondo and Unruh (Hemiptera: Monophlebidae). Las dos especies de coccinélidos se diagnostican y se ilustran en detalle. Se provee también información actualizada sobre sus biologías, hospederos y distribución geográfica

    Antisymmetric tensor Z_p gauge symmetries in field theory and string theory

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    We consider discrete gauge symmetries in D dimensions arising as remnants of broken continuous gauge symmetries carried by general antisymmetric tensor fields, rather than by standard 1-forms. The lagrangian for such a general Zp{\bf Z}_p gauge theory can be described in terms of a rr-form gauge field made massive by a (r1)(r-1)-form, or other dual realizations, that we also discuss. The theory contains charged topological defects of different dimensionalities, generalizing the familiar charged particles and strings in D=4. We describe realizations in string theory compactifications with torsion cycles, or with background field strength fluxes. We also provide examples of non-abelian discrete groups, for which the group elements are associated with charged objects of different dimensionality.Comment: 16 pages; v2: references added and typos fixe
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