Bell inequalities for continuous-variable correlations

We derive a new class of correlation Bell-type inequalities. The inequalities are valid for any number of outcomes of two observables per each of n parties, including continuous and unbounded observables. We show that there are no first-moment correlation Bell inequalities for that scenario, but such inequalities can be found if one considers at least second moments. The derivation stems from a simple variance inequality by setting local commutators to zero. We show that above a constant detector efficiency threshold, the continuous variable Bell violation can survive even in the macroscopic limit of large n. This method can be used to derive other well-known Bell inequalities, shedding new light on the importance of non-commutativity for violations of local realism.Comment: 4 pages, 1 figure. v2: New results on detector efficiencies and macroscopic limit, new co-author, changed title and abstract, changed figure, added journal reference and DO

Two-dimensional electron gas in a uniform magnetic field in the presence of a delta-impurity

The density of states and the Hall conductivity of a two-dimensional electron gas in a uniform magnetic field and in the presence of a delta impurity are exactly calculated using elementary field theoretic techniques. Although these results are not new, our treatment is explicitly gauge-invariant, and can be easily adapted to other problems involving a delta potential.Comment: 12+1 pages, 1 ps figure, REVTEX. Corrigendum adde

Mirando hacia el norte: clase, genero y etnicidad en los espacios de fruticultura del Nordeste de Brasil.

Este trabajo examina aspectos de la globalizació de los sistemas agroalimentarios, enfatizando los cambios socioeconómicos que tienen lugar en las nuevas regiones de fruticultura orientadas para los mercados del norte, según las dimensiones de clase, género y etnicidad. Las estrategias productivas usadas por los actores implicados para atender los requerimientos de calidad de las frutas, así como el contexto de las relaciones entre lo global y lo local, son analizadas, teniendo como base las investigaciones realizadas en el Nordeste brasileño

Indexação de plantas básicas de citros da Embrapa Mandioca e Fruticultura para a presença de viróides.

Os citros são hospedeiros naturais de espécies de viróides: viróide da exocorte dos citros (Citrus exocortis viroid, CEVd), viróide do nanismo do lúpulo (Hop stunt viroid, HSVd), Citrus bark cracking viroid (CBCVd), viróide da folha curvada dos citros (Citrus bent leaf viroid, CBLVd), viróide do nanismo dos citros (Citrus dwarfing viroid, CDVd) e, mais recentemente, também foi descrita a ocorrência do Citrus Viroid V (CVd-V) e Citrus viroid VI (CVd-VI). Somente o CEVd e variantes do HSVd são agentes causais de doenças, exocorte e xiloporose, respectivamente. No Brasil já foram identificados as espécies CEVd, HSVd e o CDVd

Geometrically induced singular behavior of entanglement

We show that the geometry of the set of quantum states plays a crucial role in the behavior of entanglement in different physical systems. More specifically it is shown that singular points at the border of the set of unentangled states appear as singularities in the dynamics of entanglement of smoothly varying quantum states. We illustrate this result by implementing a photonic parametric down conversion experiment. Moreover, this effect is connected to recently discovered singularities in condensed matter models.Comment: v2: 4 pags, 4 figs. A discussion before the proof of Proposition 1 and tomographic results were included, Propostion 2 was removed and the references were fixe

Antimicrobial activity of silver nanoparticles synthesized by the fungus Curvularia inaequalis

Silver nanoparticles have been widely reported in literature due to their vast industrial application in different areas. In this work, we explored a simple procedure for the biosynthesis of silver nanoparticles at room temperature from the action of Curvularia inaequalis as reduction agent. The degree of aggregation and size of biosynthesized particles were optimized from a factorial design involving combined variation of three different parameters of preparation. The resulting colloidal dispersion of silver nanoparticles presented strong antimicrobial activity against Escherichia coli and Klebsiella pneumoniae in an indication that C. inaequalis represents a new potential candidate for alternative biosynthesis of silver nanoparticles with antimicrobial activity.Keywords: Antimicrobial activity, fungi, silver nanoparticlesAfrican Journal of Biotechnology Vol. 12(20), pp. 2917-292

Estabelecimento da técnica de RT-PCR para detecção do Citrus tristeza vírus.

A citricultura é uma das mais importantes atividades do agronegócio brasileiro. O Brasil é o maior produtor mundial de citros e a Bahia ocupa o segundo lugar na produção de frutas cítricas brasileiras, que são produzidas, em base familiar, em quase todas as regiões do Estado, o que disponibiliza emprego para cerca de 100 mil trabalhadores na sua cadeia produtiva

Estratégias para o uso sustentável da biodiversidade da caatinga.

Potencial forrageiro e frutífero; Potencial medicinal; Potencial madeireiro; Potencial faunístico; Problemática da região; Recurso florestais; Áreas degradadas; Pecuária; Agricultura