23,944 research outputs found

    Hartle-Hawking Wave-Function for Flux Compactifications

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    We argue that the topological string partition function, which has been known to correspond to a wave-function, can be interpreted as an exact ``wave-function of the universe'' in the mini-superspace sector of physical superstring theory. This realizes the idea of Hartle and Hawking in the context of string theory, including all loop quantum corrections. The mini-superspace approximation is justified as an exact description of BPS quantities. Moreover this proposal leads to a conceptual explanation of the recent observation that the black hole entropy is the square of the topological string wave-function. This wave-function can be interpreted in the context of flux compactification of all spatial dimensions as providing a physical probability distribution on the moduli space of string compactification. Euclidean time is realized holographically in this setup.Comment: 37 pages, 2 figure

    Declining autonomy at work in the EU and its effect on civic behaviour

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    The aim of this paper is to show that social benefits may accrue from work environments that support autonomous forms of work. Based on social psychology, economics and philosophy approaches, we argue that autonomy is a basic human need which, when satisfied, enhances civic behavior. Using individual data from the EWCS, we find evidence of the positive effect of work autonomy on volunteer work and political/trade union activities. Overall, work autonomy has decreased over the last fifteen years for all skill levels in the EU, though there are substantial differences between countries. Organizational practices that promote autonomy should be deliberately stimulated if civic participation is to be furthered.FC

    Produção de raízes finas em floresta secundária na Amazônia Oriental: resposta à irrigação durante a época seca.

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    Raízes finas exercem papel importante em processos biogequímicos nos ecossistemas terrestres, no entanto, existem poucas informações sobre a dinâmica da produção de raízes finas e a sua resposta a fatores abióticos em florestas tropicais. O objetivo deste estudo foi avaliar a resposta da produção de raízes finas à alteração na disponibilidade de água no solo em um sítio de floresta secundária na Amazônia Oriental..

    Rare coral under the genomic microscope: timing and relationships among Hawaiian Montipora

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    Background Evolutionary patterns of scleractinian (stony) corals are difficult to infer given the existence of few diagnostic characters and pervasive phenotypic plasticity. A previous study of Hawaiian Montipora (Scleractinia: Acroporidae) based on five partial mitochondrial and two nuclear genes revealed the existence of a species complex, grouping one of the rarest known species (M. dilatata, which is listed as Endangered by the International Union for Conservation of Nature - IUCN) with widespread corals of very different colony growth forms (M. flabellata and M. cf. turgescens). These previous results could result from a lack of resolution due to a limited number of markers, compositional heterogeneity or reflect biological processes such as incomplete lineage sorting (ILS) or introgression. Results All 13 mitochondrial protein-coding genes from 55 scleractinians (14 lineages from this study) were used to evaluate if a recent origin of the M. dilatata species complex or rate heterogeneity could be compromising phylogenetic inference. Rate heterogeneity detected in the mitochondrial data set seems to have no significant impacts on the phylogenies but clearly affects age estimates. Dating analyses show different estimations for the speciation of M. dilatata species complex depending on whether taking compositional heterogeneity into account (0.8 [0.05–2.6] Myr) or assuming rate homogeneity (0.4 [0.14–0.75] Myr). Genomic data also provided evidence of introgression among all analysed samples of the complex. RADseq data indicated that M. capitata colour morphs may have a genetic basis. Conclusions Despite the volume of data (over 60,000 SNPs), phylogenetic relationships within the M. dilatata species complex remain unresolved most likely due to a recent origin and ongoing introgression. Species delimitation with genomic data is not concordant with the current taxonomy, which does not reflect the true diversity of this group. Nominal species within the complex are either undergoing a speciation process or represent ecomorphs exhibiting phenotypic polymorphisms.info:eu-repo/semantics/publishedVersio

    Instanton Corrected Non-Supersymmetric Attractors

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    We discuss non-supersymmetric attractors with an instanton correction in Type IIA string theory compactified on a Calabi-Yau three-fold at large volume. For a stable non-supersymmetric black hole, the attractor point must minimize the effective black hole potential. We study the supersymmetric as well as non-supersymmetric attractors for the D0-D4 system with instanton corrections. We show that in simple models, like the STU model, the flat directions of the mass matrix can be lifted by a suitable choice of the instanton parameters.Comment: Minor modifications, Corrected typos, 38 pages, 1 figur

    Sanitizing the fortress: protection of ant brood and nest material by worker antibiotics

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    Social groups are at particular risk for parasite infection, which is heightened in eusocial insects by the low genetic diversity of individuals within a colony. To combat this, adult ants have evolved a suite of defenses to protect each other, including the production of antimicrobial secretions. However, it is the brood in a colony that are most vulnerable to parasites because their individual defenses are limited, and the nest material in which ants live is also likely to be prone to colonization by potential parasites. Here, we investigate in two ant species whether adult workers use their antimicrobial secretions not only to protect each other but also to sanitize the vulnerable brood and nest material. We find that, in both leaf-cutting ants and weaver ants, the survival of the brood was reduced and the sporulation of parasitic fungi from them increased, when the workers nursing them lacked functional antimicrobial-producing glands. This was the case for both larvae that were experimentally treated with a fungal parasite (Metarhizium) and control larvae which developed infections of an opportunistic fungal parasite (Aspergillus). Similarly, fungi were more likely to grow on the nest material of both ant species if the glands of attending workers were blocked. The results show that the defense of brood and sanitization of nest material are important functions of the antimicrobial secretions of adult ants and that ubiquitous, opportunistic fungi may be a more important driver of the evolution of these defenses than rarer, specialist parasites

    Eigenfunctions of the Laplacian and associated Ruelle operator

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    Let Γ\Gamma be a co-compact Fuchsian group of isometries on the Poincar\'e disk \DD and Δ\Delta the corresponding hyperbolic Laplace operator. Any smooth eigenfunction ff of Δ\Delta, equivariant by Γ\Gamma with real eigenvalue λ=s(1s)\lambda=-s(1-s), where s=1/2+its={1/2}+ it, admits an integral representation by a distribution \dd_{f,s} (the Helgason distribution) which is equivariant by Γ\Gamma and supported at infinity \partial\DD=\SS^1. The geodesic flow on the compact surface \DD/\Gamma is conjugate to a suspension over a natural extension of a piecewise analytic map T:\SS^1\to\SS^1, the so-called Bowen-Series transformation. Let s\ll_s be the complex Ruelle transfer operator associated to the jacobian slnT-s\ln |T'|. M. Pollicott showed that \dd_{f,s} is an eigenfunction of the dual operator s\ll_s^* for the eigenvalue 1. Here we show the existence of a (nonzero) piecewise real analytic eigenfunction ψf,s\psi_{f,s} of s\ll_s for the eigenvalue 1, given by an integral formula \psi_{f,s} (\xi)=\int \frac{J(\xi,\eta)}{|\xi-\eta|^{2s}} \dd_{f,s} (d\eta), \noindent where J(ξ,η)J(\xi,\eta) is a {0,1}\{0,1\}-valued piecewise constant function whose definition depends upon the geometry of the Dirichlet fundamental domain representing the surface \DD/\Gamma

    Interactive technologies in stroke recovery : uncovering challenges and opportunities through physiotherapist’s perspective

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    Abstract in proceedings of the Fourth International Congress of CiiEM: Health, Well-Being and Ageing in the 21st Century, held at Egas Moniz’ University Campus in Monte de Caparica, Almada, from 3–5 June 2019.This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.info:eu-repo/semantics/publishedVersio
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