Nernst branes from special geometry

We construct new black brane solutions in $U(1)$ gauged ${\cal N}=2$ supergravity with a general cubic prepotential, which have entropy density $s\sim T^{1/3}$ as $T \rightarrow 0$ and thus satisfy the Nernst Law. By using the real formulation of special geometry, we are able to obtain analytical solutions in closed form as functions of two parameters, the temperature $T$ and the chemical potential $\mu$. Our solutions interpolate between hyperscaling violating Lifshitz geometries with $(z,\theta)=(0,2)$ at the horizon and $(z,\theta)=(1,-1)$ at infinity. In the zero temperature limit, where the entropy density goes to zero, we recover the extremal Nernst branes of Barisch et al, and the parameters of the near horizon geometry change to $(z,\theta)=(3,1)$.Comment: 37 pages. v2: numerical pre-factors of scalar fields q_A corrected in Section 3. No changes to conclusions. References adde

Universal thermal and electrical conductivity from holography

It is known from earlier work of Iqbal, Liu (arXiv:0809.3808) that the boundary transport coefficients such as electrical conductivity (at vanishing chemical potential), shear viscosity etc. at low frequency and finite temperature can be expressed in terms of geometrical quantities evaluated at the horizon. In the case of electrical conductivity, at zero chemical potential gauge field fluctuation and metric fluctuation decouples, resulting in a trivial flow from horizon to boundary. In the presence of chemical potential, the story becomes complicated due to the fact that gauge field and metric fluctuation can no longer be decoupled. This results in a nontrivial flow from horizon to boundary. Though horizon conductivity can be expressed in terms of geometrical quantities evaluated at the horizon, there exist no such neat result for electrical conductivity at the boundary. In this paper we propose an expression for boundary conductivity expressed in terms of geometrical quantities evaluated at the horizon and thermodynamical quantities. We also consider the theory at finite cutoff outside the horizon (arXiv:1006.1902) and give an expression for cutoff dependent electrical conductivity, which interpolates smoothly between horizon conductivity and boundary conductivity . Using the results about the electrical conductivity we gain much insight into the universality of thermal conductivity to viscosity ratio proposed in arXiv:0912.2719.Comment: An appendix added discussing relation between boundary conductivity and universal conductivity of stretched horizon, version to be published in JHE

A scalar field condensation instability of rotating anti-de Sitter black holes

Near-extreme Reissner-Nordstrom-anti-de Sitter black holes are unstable against the condensation of an uncharged scalar field with mass close to the Breitenlohner-Freedman bound. It is shown that a similar instability afflicts near-extreme large rotating AdS black holes, and near-extreme hyperbolic Schwarzschild-AdS black holes. The resulting nonlinear hairy black hole solutions are determined numerically. Some stability results for (possibly charged) scalar fields in black hole backgrounds are proved. For most of the extreme black holes we consider, these demonstrate stability if the ``effective mass" respects the near-horizon BF bound. Small spherical Reissner-Nordstrom-AdS black holes are an interesting exception to this result.Comment: 34 pages; 13 figure

The Sound of Topology in the AdS/CFT Correspondence

Using the gauge/gravity correspondence, we study the properties of 2-point correlation functions of finite-temperature strongly coupled gauge field theories, defined on a curved space of general spatial topology with a dual black hole description. We derive approximate asymptotic expressions for the correlation functions and their poles, supported by exact numerical calculations, and study their dependence on the dimension of spacetime and the spatial topology. The asymptotic structure of the correlation functions depends on the relation between the spatial curvature and the temperature, and is noticeable when they are of the same order. In the case of a hyperbolic topology, a specific temperature is identified for which exact analytical solutions exist for all types of perturbations. The asymptotic structure of the correlation functions poles is found to behave in a non-smooth manner when approaching this temperature.Comment: 65 pages, LaTeX, 21 figures, 1 table; fixed a small error in subsection 3.

A HISTÓRICA CONCEPÇÃO DE DESENVOLVIMENTO FRENTE ÀS IDENTIDADES REGIONAIS: O CASO DO RINCÃO DOS MENDES NO MUNICÍPIO DE ROSÁRIO DO SUL/RS

O presente artigo propõe uma reflexão sobre o enfoque convencional de desenvolvimento da região denominada de Metade Sul do Rio Grande do Sul, tomando como referência uma comunidade situada na APA do Ibirapuitã, no município de Rosário do Sul. As abordagens atuais, apoiadas em indicadores como PIB per capta, Valor Adicionado Fiscal e geração de postos de trabalho, consideram a região como pouco desenvolvida. Entre as estratégias utilizadas para reversão desse quadro destacam-se a expansão das modernas lavouras empresarias de arroz e soja e o fomento aos empreendimentos no ramo florestal. Assim, a pergunta central desse artigo é sobre a capacidade dessas estratégias em promover verdadeiramente o “desenvolvimento” da metade sul do RS. O estudo destaca os possíveis impactos das estratégias convencionais de desenvolvimento na complexa situação sócio-ambiental da região e sugere a necessidade de aprofundar os conhecimentos sobre as especificidades locais, considerando os princípios de sustentabilidade.------------------------------------------------This paper proposes a reflection about the troubles with actual development approach used in the southern half region in the Rio Grande do Sul state. The case study use as reference a community located in the APA do Rio Ibirapuitã at Rosário do Sul County. The actual approaches using GDP per capita, Value Added Tax and job generation, consider the region as poorly developed. Among the strategies used to reversal of this framework the increase of rice and soybean crop production and forest crop are used. Thus, the central question of this article is these strategies in fact to support the "development" of the southern half of the RS. The study highlights the potential impact of conventional development strategies in the complex socio-environmental region situation and suggests more investigation to recognize specific location situation, considering the principles of sustainability.Desenvolvimento, Metade sul do RS, Identidade Territorial, Development, southern half of the RS, International Development,

Hairy black holes and solitons in global AdS 5

We use a mix of analytic and numerical methods to exhaustively study a class of asymptotically global AdS solitons and hairy black hole solutions in negative cosmological constant Einstein Maxwell gravity coupled to a charged massless scalar field. Our results depend sensitively on the charge 'e' of the scalar field. The solitonic branch of solutions we study hit the Chandrashekhar limit at finite mass at small 'e', but extends to arbitrarily large mass at larger 'e'. At low values of 'e' no hairy black holes exist. At intermediate values of 'e' hairy black holes exist above a critical charge. At large 'e' hairy black holes exist at all values of the charge. The lowest mass hairy black holes is a smooth zero entropy soliton at small charge, but a (probably) singular nonzero entropy hairy black hole at larger charge. In a phase diagram of solutions, the hairy black holes merge with the familiar Reissner-Nordstrom-AdS black holes along a curve that is determined by the onset of the superradiant instability in the latter family.Comment: 80 pages. 25 Figures. RevTex4 format. v2: added discussions on second soliton branch and on planar limit; matches published versio

Review: potential biotechnological assets related to plant immunity modulation applicable in engineering disease-resistant crops.

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Habilidades De Enfrentamento Antecipatório Para Abstinência De Substâncias: Construção De Um Novo Instrumento De Medida

Anticipatory coping skills are important for the maintenance of abstinence from alcohol and other drugs. Nevertheless, there are no instruments available to evaluate them in the Brazilian context. This paper describes the first developments of an instrument that permits the assessment of this repertoire, which involved several steps. Initially, based on the literature, on similar instruments and interviews, 92 items were written, including 14 skills classes, defined and exemplified in the text. Referees conducted the semantic and content analyses, and 24 items were excluded from the list. This new version was submitted to an operational pre test and a pilot study with participants treated for abuse or addiction to alcohol or other drugs. New adjustments were made and the final set of 67 items was named Anticipatory Coping Skills Inventory for Abstinence from Alcohol and Other Drugs (IDHEA-AD, as in Portuguese). Each one of those steps is discussed and proposals for future studies are presented.Las habilidades de enfrentamiento anticipado son importantes para mantener la abstinencia de alcohol y otras drogas. A pesar de eso, no se dispone de instrumentos para evaluarlas en el contexto brasilero. Este artículo describe las etapas iniciales de la construcción de un instrumento de medida para evaluar este repertorio, lo que incluyó varias etapas. Inicialmente, con base en la literatura, en instrumentos semejantes y en entrevistas, fueron redactados 92 ítems, que contemplaban 14 clases de habilidades, definidas y ejemplificadas en el texto. La calidad semántica y el contenido de los ítems fueron evaluados por jueces, de lo cual resultó la eliminación de 24 de ellos. La nueva versión pasó por un pretest de funcionamiento y por un estudio piloto con participantes en tratamiento por abuso o dependencia de alcohol u otras drogas. Nuevos ajustes fueron realizados y el conjunto final, de 67 ítems, recibió el nombre de Inventario de Habilidades de Enfrentamiento Anticipado para Abstinencia de Alcohol y Otras Drogas (IDHEA-AD). En el artículo se discuten cada una de las etapas y son presentadas propuestas para estudios futuros.Habilidades de enfrentamento antecipatório são importantes para a manutenção da abstinência de álcool e outras drogas. Apesar disso, não se dispõe de instrumentos para avaliá-las em contexto brasileiro. Este artigo descreve as etapas iniciais da construção de um instrumento de medida para a avaliação desse repertório, o que envolveu várias etapas. Inicialmente, com base na literatura, em instrumentos semelhantes e em entrevistas, foram redigidos 92 itens, que contemplavam 14 classes de habilidades, definidas e exemplificadas no texto. A qualidade semântica e de construto dos itens foi aferida por juízes resultando na eliminação de 24 itens. A nova versão, passou por um pré-teste de funcionamento e estudo piloto com participantes em tratamento de abuso ou dependência de álcool ou outras drogas. Novos ajustes foram realizados e o conjunto final, de 67 itens, recebeu o nome de Inventário de Habilidades de Enfrentamento Antecipatório para Abstinência de Álcool e Outras Drogas (IDHEA-AD). Discute-se cada uma das etapas e são apresentadas propostas para estudos futuros

Nernst branes in gauged supergravity

We study static black brane solutions in the context of N = 2 U(1) gauged supergravity in four dimensions. Using the formalism of first-order flow equations, we construct novel extremal black brane solutions including examples of Nernst branes, i.e. extremal black brane solutions with vanishing entropy density. We also discuss a class of non-extremal generalizations which is captured by the first-order formalism.Comment: 44 pages, 3 figures, v2: added appendix B and references, minor typographic changes, v3: added some clarifying remarks, version published in JHE