1,123 research outputs found

    Evolutionary mechanisms for camouflage in Cladomorphus phyllinus (Phasmatodea): a reflection on the role of evidence for hypotheses proposition

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    We address and discuss some of the many fl aws exhibited by Costa et al. (2019) which tried to explain the twig-like camoufl age of Cladomorphus phyllinus. Given the lack of both empirical and theoretical underpinnings in Costa et al. (2019), we call into question the validity of their conclusions, in particular, that horizontal gene transfer is a causal mechanism for the camoufl age in C. phyllinus

    Castor oil-based polyurethane/S2 glass/aramid hybrid composites manufactured by vacuum infusion

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    This study evaluates the hybridization effect of S2-glass/aramid on polyurethane (PU) composites produced by vacuum infusion. Different laminates were produced with similar thickness (around 2.5 mm), using, as reinforcement, only aramid fabrics (five layers, named as K5 ) or only S2-glass fabrics (eight layers, named as G8 ). Furthermore, hybridization was obtained by manufacturing symmetrical hybrid inter-ply laminates, with four S2-glass layers and two of aramid, (G2K)S and (KG2 )S. The mechanical response of the laminates was evaluated in tensile, interlaminar shear strength, dynamical mechanical analysis and quasi-static indentation tests, and related to their morphological characteristics. The main results show that the pure glass composites presented less voids, but a higher density as well as higher tensile stiffness and strength. The aramid laminates showed a high capability for absorbing impact energy (ca. 30% higher than the pure glass laminates), and the hybrid laminates had intermediate properties. More importantly, this work shows the possibility of using a polyurethane matrix for vacuum infusion processing, effective even for aramid/S2-glass hybrid composites with thermoset polyurethane resin. This study is therefore promising for impact absorption in applications such as protective armor. The studied hybrid laminate may display a suitable set of properties and greater energy absorption capability and penetration resistance for impact applications

    Um sistema de assistência reflexiva para auto avaliação de desempenho profissional na área de desenvolvimento de software

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    Alguns dos desafios enfrentados por profissionais das mais diversas áreas de atuação são a dificuldade na organização de atividades relacionadas à educação continuada e a necessidade do se acompanhar as metodologias emergentes. Por outro lado, as organizações buscam colaboradores capacitados para encontrarem no menor tempo possível as soluções mais adequadas para seus desafios e problemas, e que tenham uma visão realista sobre suas habilidades profissionais. Nesse contexto, este trabalho propõe um sistema de assistência que apoie o processo de gestão da educação continuada e do desempenho do profissional de desenvolvimento de software

    CFT/CFT interpolating RG flows and the holographic c-function

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    We consider holographic RG flows which interpolate between non-trivial ultra-violet (UV) and infra-red (IR) conformal fixed points. We study the ``superpotentials'' which characterize different flows and discuss their expansions near the fixed points. Then we focus on the holographic cc-function as defined from the two-point function of the stress-energy tensor. We point out that the equation for the metric fluctuations in the background flow is equivalent to a scattering problem and we use this to obtain an expression for the cc-function in terms of the associated Jost functions. We propose two explicit models that realize UV-IR flows. In the first example we consider a thin wall separating two AdS spaces with different radii, while in the second one the UV region is replaced with an asymptotically AdS space. We find that the holographic cc-function obeys the expected properties. In particular it reduces to the correct -- nonzero -- central charge in the IR limit.Comment: 20 pages, discussion at the end of sec. 3 and sec. 4.1 change

    ESTRATÉGIAS PARA TRANSFORMAÇÃO DIGITAL EM MODELOS DE GESTÃO PARA RESTAURANTES UNIVERSITÁRIOS

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    O objetivo desta pesquisa é identificar, com base na literatura, os modelos de gestão utilizados em restaurantes universitários (RUs) e propor uma solução digital que otimize as práticas de gestão nesses ambientes. Para tanto, a revisão de literatura discute sobre transformação digital e modelos de gestão em restaurantes universitários. A pesquisa trata de um estudo de caso, fundamentada numa revisão narrativa de literatura e coleta de dados por meio de entrevistas semiestruturadas com gestores em nível estratégico. O estudo contribui com análises acerca dos modelos de gestão em RUs a fim de identificar elementos relevantes à proposição de uma solução digital capaz de instrumentalizar gestores que atuam num contexto de alta complexidade e ambiguidade. Conclui que a autogestão se mostrou o modelo mais adequado para esse tipo de restaurante e que a implementação de uma plataforma digital, elaborada por meio da colaboração em rede de todas as IFES, pode ser uma ação que ofereça efetividade para a atuação dos RUs. O estudo se limitou a analisar os modelos de gestão em RUs tomando como referência a realidade de uma universidade federal brasileira. Para estudos futuros, sugere-se a realização de pesquisa com todas as IFES, a fim de analisar os modelos de gestão utilizados, de forma comparativa e aprofundada

    Holographic Renormalization and Ward Identities with the Hamilton-Jacobi Method

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    A systematic procedure for performing holographic renormalization, which makes use of the Hamilton-Jacobi method, is proposed and applied to a bulk theory of gravity interacting with a scalar field and a U(1) gauge field in the Stueckelberg formalism. We describe how the power divergences are obtained as solutions of a set of "descent equations" stemming from the radial Hamiltonian constraint of the theory. In addition, we isolate the logarithmic divergences, which are closely related to anomalies. The method allows to determine also the exact one-point functions of the dual field theory. Using the other Hamiltonian constraints of the bulk theory, we derive the Ward identities for diffeomorphisms and gauge invariance. In particular, we demonstrate the breaking of U(1)_R current conservation, recovering the holographic chiral anomaly recently discussed in hep-th/0112119 and hep-th/0202056.Comment: 31 pages; v2: references added. Version published in Nuclear Physics
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