Stationary entanglement induced by dissipation

The dynamics of two two-level dipole-dipole interacting atoms coupled to a common electromagnetic bath and closely located inside a lossy cavity, is reported. Initially injecting only one excitation in the two atoms-cavity system, loss mechanisms asymptotically drive the matter sample toward a stationary maximally entangled state. The role played by the closeness of the two atoms with respect to such a cooperative behaviour is carefully discussed. Stationary radiation trapping effects are found and transparently interpreted.Comment: 1 figure, submitted to Phys. Rev. Let

Vaccine and Vaccination: On Field Research

Historically, vaccinations have enabled the eradication, elimination, and control of many debilitating diseases [...]

Chiral Rings of Deconstructive [SU(n_c)]^N Quivers

Dimensional deconstruction of 5D SQCD with general n_c, n_f and k_CS gives rise to 4D N=1 gauge theories with large quivers of SU(n_c) gauge factors. We construct the chiral rings of such [SU(n_c)]^N theories, off-shell and on-shell. Our results are broadly similar to the chiral rings of single U(n_c) theories with both adjoint and fundamental matter, but there are also some noteworthy differences such as nonlocal meson-like operators where the quark and antiquark fields belong to different nodes of the quiver. And because our gauge groups are SU(n_c) rather than U(n_c), our chiral rings also contain a whole zoo of baryonic and antibaryonic operators.Comment: 93 pages, LaTeX, PSTricks macros; 1 reference added in v

Contribuição de variáveis ambientais à estrutura de comunidade de anuros no Domínio da Caatinga of Brazil

To ascertain the influence of environmental variables on the structure of anuran communities, we conducted tests to determine which variables best explain the spatial distribution patterns of different communities of anurans in a rocky, montane environment characterized mainly by open habitats and gallery forests. The study area is the Sete Passagens State Park in the State of Bahia, Brazil, an area included in the Chapada Diamantina Region and in the Caatinga Morphoclimatic Domain. We sampled 20 plots (60 × 25 m) during two rainy seasons, and measured 13 environmental variables. The environmental matrix was reduced to four synthetic axes through the principal component analysi, and the anuran community matrix was reduced to a synthetic axis through the non-metric multidimensional scaling method. We tested the association between environmental axes (independent variables) and community composition (dependent variable) using a multiple regression analysis. The single axis significantly associated with the species of anurans found in any given plot is Principal Component 1, in which the major contributors to variation are factors involving vegetation structure, listed in descending order, as follow: percentage of leaf litter, density of trees, canopy height, soil moisture, and percentage of understory, shrub, and herb layers. The ordination of the anuran community showed an environmental gradient from the Campo Rupestre to Semideciduous Forest patches, characterized mainly by the gradual increase of layering in the vegetation.O objetivo do presente estudo foi verificar a influência de variáveis ambientais na estrutura de comunidade de anuros, testando quais variáveis ambientais melhor explicam os padrões de distribuição espacial das comunidades dos anuros em ambiente montanhoso caracterizado essencialmente por ambientes abertos e florestas de galeria. A área de estudo é o Parque Estadual das Sete Passagens, no Estado da Bahia, Brasil, uma área incluída na região da Chapada Diamantina e no Domínio Morfoclimático da Caatinga. Amostramos 20 réplicas (60 × 25 m) durante duas estações chuvosas e mensuramos 13 variáveis ambientais. A matriz ambiental foi reduzida a quatro eixos sintéticos através da análise dos componentes principais e a matriz da comunidade de anuros foi reduzida a um eixo sintético por meio do método de escalonamento multidimensional não-métrico. Testamos a hipótese nula de ausência de associação entre os eixos ambientais (variáveis independentes) e a composição da comunidade (variável dependente) por meio da análise de regressão múltipla. O Componente Principal 1 foi o único eixo significativamente associado à composição de anuros, com variáveis de maior contribuição diretamente relacionadas à estrutura da vegetação (ordem decrescente): porcentagem de serapilheira, densidade de lenhosas, altura do dossel, umidade do solo e porcentagem de subbosque, arbustos e herbáceas. A ordenação da comunidade de anuros evidenciou um gradiente ambiental do Campo Rupestre para manchas de Floresta Semi-decidual, principalmente caracterizado pelo aumento gradual da estratificação da vegetação

Theoretical analysis of a recent experiment on mesoscopic state superpositions in cavity QED

Quite recently quantum features exhibited by a mesoscopic field interacting with a single Rydberg atom in a microwave cavity has been observed (A. Auffeves et al., Phys. Rev. Lett. 91, 230405, 2003). In this paper we theoretically analyze all the phases of this articulated experiment considering from the very beginning cavity losses. Fully applying the theory of quantum open systems, our modelization succeeds in predicting fine aspects of the measured quantity, reaching qualitative and quantitative good agreement with the experimental results. This fact validates our theoretical approach based on the fundamental atom-cavity interaction model and simple mathematical structure of dissipative superoperators

Agriculture and Sustainability: a GIS Based Model to Appraise Incentive Policy

Agriculture is the major form of protection of local identities and sustainability and one of the most fragile Italian economic sectors, exposed to fluctuations of the financial/economic crisis. As a consequence, boosting agricultural policies should integrate conflicting objectives connected to preservation and innovation, effectiveness/efficiency, and landscape features and job opportunities. Referring to a large land area located in the central part of Sicily (Italy) the paper proposes an assessment/planning pattern aimed at providing some axiological items and a specific algorithm able to appraise each specific land parcel, generating different strategies and selecting the best format of funding allocation. The pattern combines some WebGIS tools helpful for spatial analysis and management of the big data amount coming from the Landscape Regional Plan and the cadastral vector database. The general approach integrates monetary and qualitative features, as well as land estate and landscape values within a multidimensional pattern providing the quantitative conditions for supporting qualitative and sustainable development