Topological gravity localization on a delta-function like Brane

Besides the String Theory context, the quantum General Relativity can be studied by the use of constrained topological field theories. In the celebrated Plebanski formalism, the constraints connecting topological field theories and gravity are imposed in space-times with trivial topology. In the braneworld context there are two distinct regions of the space-time, namely, the bulk and the braneworld volume. In this work we show how to construct topological gravity in a scenario containing one extra dimension and a delta-function like 3-brane which naturally emerges from a spontaneously broken discrete symmetry. Starting from a D=5 theory we obtain the action for General Relativity in the Palatini form in the bulk as well as in the braneworld volume. This result is important for future insights about quantum gravity in brane scenarios.Comment: 4 page

Impacto econômico de pesquisa da Embrapa no bioma caatinga com variedade de mandioca (Manihot esculenta Crantz) resistente à bacteriose.

Neste artigo é analisada a viabilidade econômica de investimento em pesquisa pública da Embrapa para o desenvolvimento de variedades de mandioca resistentes à bacteriose e adaptadas ao bioma caatinga. A bacteriose é a principal doença da mandiocultura na microrregião de Guanambi, no Estado da Bahia, e o estresse hídrico um dos grandes desafios ao incremento do rendimento e da produção na região Nordeste. Com base nesse conhecimento e com o objetivo de evitar o avanço da bacteriose e simultaneamente revitalizar a mandiocultura da microrregião de Guanambi, a Embrapa Mandioca e Fruticultura (CNPMF), com a colaboração da Embrapa Cerrados (CPAC) e agricultores familiares da microrregião, uniram esforços num programa participativo de seleção de variedades de mandioca resistentes à bacteriose e adaptadas às condições locais. O programa teve início em 1997; ano em que a doença foi identificada na microrregião por uma equipe de pesquisadores da Embrapa Mandioca e Fruticultura. Desse esforço conjunto foi selecionada a variedade de mandioca de nome BRS Formosa; que atualmente está sendo utilizada em escala comercial por agricultores familiares da microrregião de Guanambi

Influence of the external pressure on the quantum correlations of molecular magnets

The study of quantum correlations in solid state systems is a large avenue for research and their detection and manipulation are an actual challenge to overcome. In this context, we show by using first-principles calculations on the prototype material KNaCuSi$_{4}$O$_{10}$ that the degree of quantum correlations in this spin cluster system can be managed by external hydrostatic pressure. Our results open the doors for research in detection and manipulation of quantum correlations in magnetic systems with promising applications in quantum information science

Nearest neighbor embedding with different time delays

A nearest neighbor based selection of time delays for phase space reconstruction is proposed and compared to the standard use of time delayed mutual information. The possibility of using different time delays for consecutive dimensions is considered. A case study of numerically generated solutions of the Lorenz system is used for illustration. The effect of contamination with various levels of additive Gaussian white noise is discussed.Comment: 4 pages, 5 figures, updated to final versio

Results in Kalb-Ramond field localization and resonances on deformed branes

We make an analysis about several aspects of localization of the Kalb-Ramond gauge field in a specific four dimensional AdS membrane embedded in a five dimensional space-time. The membrane is generated from a deformation of the $\lambda \phi^4$ potential and belongs to a new class of defect solutions. In this context we find resonance structures in the analysis of massive modes. The study of deformed defects is important because they contain internal structures and these may have implications to the way the background space-time is constructed and the way its curvature behaves. The main objective here is to observe the contributions of the deformation procedure to the resonances and the well known field localization methods.Comment: 6 pages, 7 figures, Latex with EPL macr