993 research outputs found

    Combining lacewings and parasitoids for biological control of foxglove aphids in sweet pepper

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    The role of natural enemy diversity in biological pest control has been debated in many studies, and understanding how interactions amongst predators and parasitoids affect herbivore populations is crucial for pest management. In this study, we assessed the individual and combined use of two species of natural enemies, the parasitoid Aphidius ervi Haliday, and the predatory brown lacewing Micromus variegatus (Fabricius), on their shared prey, the foxglove aphid, Aulacorthum solani (Kaltenbach), on sweet pepper. We hypothesized that the presence of intraguild predation (IGP) and predator facilitation (through induced aphid dropping behaviour) might have both negative and positive effects on aphid control, respectively. Our greenhouse trial showed that overall, the greatest suppression of aphids occurred in the treatment with both the parasitoid and the lacewing. While the combination of lacewings and parasitoids significantly increased aphid control compared to the use of parasitoids alone, the effect was not significantly different to the treatment with only predators, although there was a clear trend of enhanced suppression. Thus, the combined effects of both species of natural enemies were between additive and non-additive, suggesting that the combination is neither positive nor negative for aphid control. High levels of IGP, as proven in the laboratory, were probably compensated for by the strong aphid suppression provided by the lacewings, whether or not supplemented with some level of predator facilitation. For aphid management over a longer time scale, it might still be useful to combine lacewings and parasitoids to ensure stable and resilient aphid control.Fil: Rocca, Margarita. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Messelink, Gerben J.. University of Agriculture Wageningen; Países Bajo

    Linear response of entanglement entropy from holography

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    For time-independent excited states in conformal field theories, the entanglement entropy of small subsystems satisfies a `first law'-like relation, in which the change in entanglement is proportional to the energy within the entangling region. Such a law holds for time-dependent scenarios as long as the state is perturbatively close to the vacuum, but is not expected otherwise. In this paper we use holography to investigate the spread of entanglement entropy for unitary evolutions of special physical interest, the so-called global quenches. We model these using AdS-Vaidya geometries. We find that the first law of entanglement is replaced by a linear response relation, in which the energy density takes the role of the source and is integrated against a time-dependent kernel with compact support. For adiabatic quenches the standard first law is recovered, while for rapid quenches the linear response includes an extra term that encodes the process of thermalization. This extra term has properties that resemble a time-dependent `relative entropy'. We propose that this quantity serves as a useful order parameter to characterize far-from-equilibrium excited states. We illustrate our findings with concrete examples, including generic power-law and periodically driven quenches.Comment: 31+3 pages, 8 figures; v2: typos fixed and references added; v3: claims on universality sharpened (section 2.1), version to appear in JHE

    Technologies to remember or forget?:A perspective from reminiscence and life review

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    This paper addresses recent technological developments in altering or even erasing memories. From a critical perspective these technologies are seen as artificial as they disrupt identities and true happiness. This basically resonates with the value attributed to remembering in the field of reminiscence and life review. From a proponent perspective it is argued that technologies have always been used to filter our memories and thereby support the dynamics of identity development. This position is consistent with a more dynamic view of reminiscence and life review that also takes different attitudes towards remembering and forgetting into account. The last part of the paper combines both perspectives in an evaluation of the use of propranolol, a drug that might contribute to willful forgetting under specific conditions. This evaluation also raises new questions for the field of reminiscence and life review

    Genomic Transformation of the Picoeukaryote Ostreococcus tauri

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    Common problems hindering rapid progress in Plant Sciences include cellular, tissue and whole organism complexity, and notably the high level of genomic redundancy affecting simple genetics in higher plants. The novel model organism Ostreococcus tauri is the smallest free-living eukaryote known to date, and possesses a greatly reduced genome size and cellular complexity(1,2), manifested by the presence of just one of most organelles (mitochondrion, chloroplast, golgi stack) per cell, and a genome containing only ~8000 genes. Furthermore, the combination of unicellularity and easy culture provides a platform amenable to chemical biology approaches. Recently, Ostreococcus has been successfully employed to study basic mechanisms underlying circadian timekeeping(3-6). Results from this model organism have impacted not only plant science, but also mammalian biology(7). This example highlights how rapid experimentation in a simple eukaryote from the green lineage can accelerate research in more complex organisms by generating testable hypotheses using methods technically feasible only in this background of reduced complexity. Knowledge of a genome and the possibility to modify genes are essential tools in any model species. Genomic(1), Transcriptomic(8), and Proteomic(9) information for this species is freely available, whereas the previously reported methods(6,10) to genetically transform Ostreococcus are known to few laboratories worldwide. In this article, the experimental methods to genetically transform this novel model organism with an overexpression construct by means of electroporation are outlined in detail, as well as the method of inclusion of transformed cells in low percentage agarose to allow selection of transformed lines originating from a single transformed cell. Following the successful application of Ostreococcus to circadian research, growing interest in Ostreococcus can be expected from diverse research areas within and outside plant sciences, including biotechnological areas. Researchers from a broad range of biological and medical sciences that work on conserved biochemical pathways may consider pursuing research in Ostreococcus, free from the genomic and organismal complexity of larger model species

    A multisided C-2 B-spline patch over extraordinary vertices in quadrilateral meshes

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    We propose a generalised B-spline construction that extends uniform bicubic B-splines to multisided regions spanned over extraordinary vertices in quadrilateral meshes. We show how the structure of the generalised Bezier patch introduced by Varady et al. can be adjusted to work with B-spline basis functions. We create ribbon surfaces based on B-splines using special basis functions. The resulting multisided surfaces are C-2 continuous internally and connect with G(2) continuity to adjacent regular and other multisided B-splines patches. We visually assess the quality of these surfaces and compare them to Catmull-Clark limit surfaces on several challenging geometrical configurations. (C) 2020 The Author(s). Published by Elsevier Ltd

    Combining lacewings and parasitoids for biological control of foxglove aphids in sweet pepper

    Get PDF
    The role of natural enemy diversity in biological pest control has been debated in many studies, and understanding how interactions amongst predators and parasitoids affect herbivore populations is crucial for pest management. In this study, we assessed the individual and combined use of two species of natural enemies, the parasitoid Aphidius ervi Haliday, and the predatory brown lacewing Micromus variegatus (Fabricius), on their shared prey, the foxglove aphid, Aulacorthum solani (Kaltenbach), on sweet pepper. We hypothesized that the presence of intraguild predation (IGP) and predator facilitation (through induced aphid dropping behaviour) might have both negative and positive effects on aphid control, respectively. Our greenhouse trial showed that overall, the greatest suppression of aphids occurred in the treatment with both the parasitoid and the lacewing. While the combination of lacewings and parasitoids significantly increased aphid control compared to the use of parasitoids alone, the effect was not significantly different to the treatment with only predators, although there was a clear trend of enhanced suppression. Thus, the combined effects of both species of natural enemies were between additive and non-additive, suggesting that the combination is neither positive nor negative for aphid control. High levels of IGP, as proven in the laboratory, were probably compensated for by the strong aphid suppression provided by the lacewings, whether or not supplemented with some level of predator facilitation. For aphid management over a longer time scale, it might still be useful to combine lacewings and parasitoids to ensure stable and resilient aphid control.Centro de Estudios Parasitológicos y de Vectore

    Multisided generalisations of Gregory patches

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    We propose two generalisations of Gregory patches to faces of any valency by using generalised barycentric coordinates in combination with two kinds of multisided Bézier patches. Our first construction builds on S-patches to generalise triangular Gregory patches. The local construction of Chiyokura and Kimura providing G1 continuity between adjoining Bézier patches is generalised so that the novel Gregory S-patches of any valency can be smoothly joined to one another. Our second construction makes a minor adjustment to the generalised Bézier patch structure to allow for cross-boundary derivatives to be defined independently per side. We show that the corresponding blending functions have the inherent ability to blend ribbon data much like the rational blending functions of Gregory patches. Both constructions take as input a polygonal mesh with vertex normals and provide G1 surfaces interpolating the input vertices and normals. Due to the full locality of the methods, they are well suited for geometric modelling as well as computer graphics applications relying on hardware tessellation

    Multisided B-spline Patches Over Extraordinary Regions

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    We propose a generalised B-spline construction that extends uniform bi-degree B-splines to multisided regions spanned over extraordinary regions in quad-dominant meshes. We show how the structure of the existing cubic multisided B-spline patch can be generalised to work with B-spline basis functions of arbitrary degree and can be spanned over extraordinary vertices as well as extraordinary faces of quad-dominant meshes. The resulting multisided surfaces are Cd-1 continuous internally and connect with Gd-1 continuity to adjacent regular and other multisided B-splines patches. In addition, we design several specialised functions that increase the visual quality of the patches, in both the extraordinary vertex and face settings.<br/

    Doctors' knowledge of patient radiation exposure from diagnostic imaging requested in the emergency department

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    Objective: To assess emergency department (ED) doctors' knowledge of radiation doses associated with diagnostic imaging and to describe their practice with regard to informing patients of risk. Design, participants and setting: Prospective, questionnaire-based observational study in May 2009 among all 110 doctors in the EDs of a 570-bed teaching hospital and a 200-bed district hospital. Main outcome measures: Percentage knowledge score; and frequency of discussing radiation risk with patients, based on responses to three scenarios rated on a visual analogue scale (VAS), where a score of 100 indicates doctors would always discuss it. Results: 96 doctors (87%) completed the questionnaire. The overall mean knowledge score was 40% (95% CI, 38%-43%). Senior doctors scored somewhat higher than junior doctors, but not significantly (42% v 39%; P = 0.75). Over three-quarters of doctors (78%) underestimated the lifetime risk of fatal cancer attributable to a single computed tomography scan of the abdomen. Most doctors (76%) reported never having had any formal training on risks to patients from radiation exposure. The frequency at which doctors would inform patients of the risk of radiation varied greatly depending on the clinical scenario (mean VAS scores, between 38 and 90). Conclusion: Emergency doctors in our sample had a varied knowledge of the risks from radiation exposure, but overall knowledge was poor. Staff should receive education, and the diagnostic imaging request process may need to include information on radiation doses and risks.Griffith Health, School of MedicineFull Tex

    The sele sentence completion questionnaire: a new instrument for the assessment of personal meaning in research on aging

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    In this paper, the SELE-instrumenits presented. The SELE-instrument is a sentence completion test and an accompanying coding scheme, which is designed to study cognitions about self and life. The related theoretical construct is the personal meaning system, which encompasses different meaning domains, like "self", "activities" and "social relations", as well as evaluations and time perspectives. It is argued that especially in aging research. it is necessarv to use more oven instruments in studying self-and-life-cognitions. A short history of sentence completion instruments in psychology, is presented in order to better understand the specific contents of the SELE-instrument. The SELE provides sentence stems in the first form singular ("I") combination with verbal factors, which express different combinations of evaluation and time perspective, to which the respondents have to react in their own words. The SELE-instrumenits thus a semi-structured questionnaire, which can be used in large-scale research. The sentence completions are coded with an extensive coding scheme, which is hierarchially and dimensionally organized. Some figures on the coding reliability as well as on the validity and stability of the instrument are presented. The different uses to which the SELE-instrument as been put are described shortly.En este articulo se presenta el instrumento SELE. Este instrumento, que consta de un cuestionario de frases incompletas y un esquema de codificación de respuestas, está diseñado para el estudio de las cogniciones sobre el self y la vida. El constructo teórico al que se aproxima es el sistema de significado personal, sistema que comprende tanto diferentes dominios de significado (por ejemplo el "self", "actividades" o "relaciones sociales") como evaluaciones y perspectivas temporales. Se argumenta que, especialmente en la investigación en envejecimiento, es necesario utilizar instrurnentos de carácter más abierto para el estudio de cogniciones relacionadas con el self y la vida. Por otra parte, para entender mejor los contenidos específicos del SELE, se presenta una breve historia de los instrumentos de frases incompletas en Psicologia. El SELE proporciona estimulos en forma de frases incompletas a los que la persona tiene que contestar en sus propias palabras. Estos estímulos comienzan con un sujeto en primera persona del singular ("Yo") seguido por una forma verbal que expresa diferentes combinaciones de perspectiva temporal y evaluación. Debido a este formato, el SELE es un cuestionario semiestructurado que puede ser utilizado en investigaciones a gran escala. Las respuestas se categorizan mediante un exhaustivo sistema de codificación que está organizado tanto jerárquica como dimensionalmente. En el articulo se presentan algunos resultados en relación con la fiabilidad, la validez y la estabilidad del cuestionario, asi como también se describen brevemente los diferentes usos a los que ha estado dirigido el SELE
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