946 research outputs found
Chemistry of Chern-Simons Supergravity: reduction to a BPS kink, oxidation to M-theory and thermodynamical aspects
We construct a supersymmetric extension of the two dimensional
Kaluza-Klein-reduced gravitational Chern-Simons term, and globally study its
solutions, labelled by mass and U(1) charge c. The kink solution is BPS, and in
an appropriate conformal frame all solutions asymptotically approach AdS. The
thermodynamics of the Hawking effect yields interesting behavior for the
specific heat and hints at a Hawking-Page-like transition at T_{critical} \sim
c^{3/2}. We address implications for higher dimensions ("oxidation"), in
particular D=3,4 and 11, and comment briefly on AdS/CFT aspects of the kink.Comment: 39 pages, 2 figures. v2: reference added, minor changes, typo
Benthic Foraminifera as Environmental Indicators in Mediterranean Marine Caves: A Review
Marine caves are characterized by wide environmental variability for the interaction between marine and continental processes. Their conditions may be defined as extreme for inhabiting organisms due to the enclosed morphology, lack of light, and scarcity of nutrients. Therefore, it is necessary to identify reliable ecological indicators for describing and assessing environmental conditions in these habitats even more than elsewhere. This review aims to provide the state of art related to the application of benthic foraminifera as proxies in the (paleo)ecological characterization of different habitats of marine caves. Special attention was addressed to a research project focused on Mediterranean marine caves with different characteristics, such as extent, morphology, freshwater influence, salinity, sediment type, oxygenation, and organic matter supply. This review aims to illustrate the reliability of foraminifera as an ecological and paleoecological indicator in these habitats. They respond to various environmental conditions with different assemblages corresponding to a very detailed habitat partitioning. Because marine caves may be considered natural laboratories for environmental variability, the results of these studies may be interpreted in the perspective of the global variability to understand the environmental drivers of future changes in marine systems
Supersymmetric black holes in 2D dilaton supergravity: baldness and extremality
We present a systematic discussion of supersymmetric solutions of 2D dilaton
supergravity. In particular those solutions which retain at least half of the
supersymmetries are ground states with respect to the bosonic Casimir function
(essentially the ADM mass). Nevertheless, by tuning the prepotential
appropriately, black hole solutions may emerge with an arbitrary number of
Killing horizons. The absence of dilatino and gravitino hair is proven.
Moreover, the impossibility of supersymmetric dS ground states and of
nonextremal black holes is confirmed, even in the presence of a dilaton. In
these derivations the knowledge of the general analytic solution of 2D dilaton
supergravity plays an important role. The latter result is addressed in the
more general context of gPSMs which have no supergravity interpretation.
Finally it is demonstrated that the inclusion of non-minimally coupled
matter, a step which is already nontrivial by itself, does not change these
features in an essential way.Comment: 30 pages, LaTeX, v2: mayor revision (rearranged title, shortened
abstract, revised introduction, inserted section from appendix to main text,
added subsection with new material on non-SUGRA gPSMs, added clarifying
remarks at some places, updated references); v3: corrected minor misprints,
added note with a new referenc
Different temperatures on mycelial growth of Corynespora cassiicola isolates causal agent of soybean target spot.
Soybean target spot caused by Corynespora cassiicola is a common disease in Brazil. The aim of this study was to evaluate different temperatures on mycelial growth of C. cassiicola isolates obtained from three soybean growing regions in Brazil. Isolates from São Paulo, Paraná and Mato Grosso states were provided by Embrapa Soja. The isolates studied were MT13, PR21, MT29, MT67, SP70, PR27, PR28, PR06, PR02 and MT04. Mycelium plug of 0.5 cm in diameter of each isolated were transferred to PDA media. The plates were incubated in BOD at 10°C, 15°C, 20°C, 23°C, 25°C, 27°C and 30°C temperatures with 12 hours photoperiod. The experimental design was randomized, with 10 isolates, 7 temperatures and 5 replicates. The assessments were made by daily measurements of mycelial growth. Mycelial growth curves were established over time for each temperature using linear regression (Y= A+BX, where Y is the mycelial growth, X is time, A is the intercept and B mycelial growth rate). A mycelial growth curve was set with the ?B? values as a function of temperature for beta generalized equation: Y = B1 ((B2-X)^B4) ((B3-X)^B5, where Y is the mycelial growth rate, X the temperature and the parameters B2 and B3 represent the minimum and maximum temperatures, respectively. The isolates grew at all temperatures studied, except PR21 isolated which did not grow at 10ºC and 30ºC temperature. The increase of temperature caused greater mycelial growth however MT13, PR 27, SP70 and PR02 showed a decrease in mycelial growth at 30ºC temperature. The minimum and maximum temperature estimated by the generalized beta function was between 7,2 ºC and 32,5ºC respectively
Mosaic of submerged habitats in the Venice lagoon shows signs of marinization
The relationships between habitat patterns and ecosystem functioning have been widely explored in terrestrial ecosystems, but less in marine and coastal ecosystems, calling for further research in this direction. This work focuses on the mosaic of submerged habitats in the Venice lagoon, Italy. It aims to describe the habitats’ spatial patterns at multiple spatial scales, and to explore their linkages with the ecological status defined according to the EU Water Framework Directive (WFD, 2000/60/EC). The submerged habitats’ mosaic has been analysed by calculating a set of seascape metrics at different spatial scales. These metrics have been linked with the biological quality elements (BQEs) that are monitored in the lagoon in compliance to the WFD. The results show that the habitats’ spatial patterns differ between the areas of the lagoon with marine-like features and the areas which still retain more lagoon characteristics. The similarity between the pattern found in the whole lagoon and those found in marine-like areas suggests a general loss of lagoon characteristics at the lagoon scale. Regarding the ecological status, every BQE seems to be associated with a different habitat configuration at the water body scale. This does not facilitate the joint improvement of the BQEs, as required by the Directive. If we cannot achieve that, at some point we will probably have to choose what to prioritize. On a broader perspective, this calls for a reflection on what lagoon we want for the future, a vision that should be shared and account for the lagoon’s complexity, current trends and challenges
Chemical-physical and ecological characterisation in the environmental project of a polluted coastal area: the Bagnoli case study
The Bagnoli Bay (southern Tyrrhenian Sea, Naples, Italy) has been impacted for about one century by heavy anthropogenic pollution due to an important steel plant. A multidisciplinary environmental research, aimed at the reclamation of the marine contaminated area, was planned in order to evaluate, through quantitative data, the chemical-physical and ecological characteristics of marine sediments; the latter ones are strictly related to the composition and structure of benthic foraminiferal assemblages. A comprehensive statistical approach, considering all data, was attempted in order to single out the influence of pollutants on the single species distribution. The results show strong heavy metal pollution (Fe, Mn, Pb and Zn) in the vicinity of the industrial plant. Many foraminiferal species (Haynesina germanica, Miliolinella subrotunda,Quinqueloculina parvula), have a good tolerance to some trace metals while, Bulimina sublimbata, Elphidiummacellum and Miliolinella dilatata show a good tolerance to PAHs pollution
Poisson-sigma model for 2D gravity with non-metricity
We present a Poisson-sigma model describing general 2D dilaton gravity with
non-metricity, torsion and curvature. It involves three arbitrary functions of
the dilaton field, two of which are well-known from metric compatible theories,
while the third one characterizes the local strength of non-metricity. As an
example we show that alpha' corrections in 2D string theory can generate
(target space) non-metricity.Comment: 9 page
Estruturação e verbalização no conhecimento social
Cento e quarenta crianças de 6 a 12 anos, de ambos os sexos, foram solicitadas a cumprir duas tarefas, baseadas no método de colocação de bonecos. Na primeira deveriam dispor um conjunto de 15 bonecos sobre uma folha de papel, e na segunda deviam tomar dois bonecos quaisquer supondo que mantivessem certo tipo de relação social e inventando o diálogo que pudessem estar travando. A análise dos resultados revela um processo psicogenético de estruturação do conhecimento social, e uma crescente antecipação das implicações do comportamento, acompanhada do aumento da complexidade do pensamento.One hundred forty six-to-twelve year old children, of both sexes, were individually asked to perform two tasks, based on the doll-placement technique. The first task consisted in arranging a set of 15 dolls on a paper sheet, as they wanted. In the second one Subjects should take two dolls at wish, and suppose there was a given social relationship between them. Subjects should also invent a supposed conversation between the chosen dolls. Data analysis showed the existence of a psychogenetic process of structuration of social knowledge leading to the notion of social relationship, as well as a progressive anticipation of behavioral implications. It was also observed that social thinking becomes increasingly complex with age. Results were discussed in terms of Piaget's theory, and of Berger and Lukmann's propositions on the nature of social reality
Piscicultura familiar: primeiros olhares e oportunidades de ação no Tocantins.
Nos últimos anos a piscicultura vem se consolidando como atividade de destaque no sistema de produção da agricultura familiar. A visão dos produtores sobre a atividade vem se modificando, deixando de ser uma atividade marginalizada na propriedade e se tornando uma alternativa de diversificação da produção. Contudo, o acesso dos produtores à extensão aquícola ainda é deficiente. O acesso às tecnologias ainda é considerado um elemento fraco na cadeia produtiva da aquicultura, sobretudo na piscicultura familiar. Apesar destes gargalos, a produção piscícola oriunda da agricultura familiar tem aumentado significativamente nos últimos anos, em especial no estado de Tocantins. O crescimento da piscicultura familiar neste estado levou a Embrapa Pesca e Aquicultura a desenvolver uma ação denominada Projeto Divinópolis, que visa identificar demandas e propor ações relacionadas à geração de tecnologias para a piscicultura familiar, além de fornecer subsídios para políticas públicas e ações de fomento. Tais ações vislumbram o fortalecimento da cadeia produtiva da piscicultura nos municípios de Divinópolis e Abreulândia, área de abrangência do projeto.Organizado por: Sílvio Ricardo Maurano; AQUACIÊNCIA 2012
Dynamic Balance and Explosive Strength Assessment by an Integrated Inertial Sensor in a Group of Elderly People
- …