Antihyperon polarization in high-energy inclusive processes

We propose a model for the antihyperon polarization in high-energy proton-nucleus inclusive reactions, based on the final-state interactions between the antihyperons and other produced particles (predominantly pions). To formulate this idea, we use the previously obtained low-energy pion-(anti-)hyperon interaction using effective chiral Lagrangians, and a hydrodynamic parametrization of the background matter, which expands and decouples at a certain freezeout temperature.

Limitation of double folding potentials to simulate the polarization in reactions involving halo nuclei

In this work, we investigate the limitation of the use of strength coefficients on double folding potentials to study the presence of the threshold anomaly in the elastic scattering of halo nuclei at near barrier energies. For this purpose, elastic angular distributions and reaction cross sections for the He-6 on Bi-209 are studied. (c) 2008 Elsevier B.V. All rights reserved.

VACUUM POLARIZATION EFFECTS ON QUASINORMAL MODES IN ELECTRICALLY CHARGED BLACK HOLE SPACE-TIMES

We investigate the influence of vacuum polarization of quantum massive fields on the scalar sector of quasinormal modes in spherically symmetric black holes. We consider the evolution of a massless scalar field on the space-time corresponding to a charged semiclassical black hole, consisting of the quantum-corrected geometry of a Reissner-Nordstrom black hole dressed by a quantum massive scalar field in the large mass limit. Using a sixth order WKB approach we find a shift in the quasinormal mode frequencies due to vacuum polarization.

Measurement of an Excited Charmonium State and the Study of J/psi Polarization in p plus p Collisions at root s=200 GeV in PHENIX Experiment at RHIC

We report the J/psi -> e(+)e(-) and the psi` -> e(+)e(-) production cross sections in the PHENIX experiment at RHIC. The first measurements of the production cross sections of the psi` and the psi` over the J/psi, will contribute to the clarification of the theoretical understanding of the J/psi meson production. The inclusive J/psi polarization through the same decay channel is also presented, showing a trend of slightly longitudinal polarization for p(T) <5 GeV/c.

Purity and entanglement of two-photon polarization states generated by spontaneous parametric down-conversion

We elucidate the dependence of purity and entanglement of two-photon states generated by spontaneous parametric down-conversion on the parameters of the source, such as crystal length, pump beam divergence, frequency bandwidth, and detectors angular aperture. The effect of crystal anisotropy is taken into account. Numerical simulations are presented for two types of commonly used source configurations. (C) 2009 Elsevier B.V. All rights reserved.

Orbital-polarization terms: From a phenomenological to a first-principles description of orbital magnetism in density-functional theory

Phenomenological orbital-polarizition (OP) terms have been repeatedly introduced in the single-particle equations of spin-density-functional theory, in order to improve the description of orbital magnetic moments in systems containing transition metal ions. Here we show that these ad hoc corrections can be interpreted as approximations to the exchange-correlation vector potential A(xc) of current-density functional theory (CDFT). This connection provides additional information on both approaches: phenomenological OP terms are connected to first-principles theory, leading to a rationale for their empirical success and a reassessment of their limitations and the approximations made in their derivation. Conversely, the connection of OP terms with CDFT leads to a set of simple approximations to the CDFT potential A(xc), with a number of desirable features that are absent from electron-gas-based functionals. (C) 2008 Wiley Periodicals, Inc.

Spin-polarization effects in homogeneous and non-homogeneous diluted magnetic semiconductor heterostructures

Spin polarization is a key characteristic in developing spintronic devices. Diluted magnetic heterostructures (DMH), where subsequent layers of conventional and diluted magnetic semiconductors (DMS) are alternate, are one of the possible ways to obtain it. Si being the basis of modern electronics, Si or other group-IV DMH can be used to build spintronic devices directly integrated with conventional ones. In this work we study the physical properties and the spin-polarization effects of p-type DMH based in group-IV semiconductors (Si, Ge, SiGe, and SiC), by performing self-consistent (k) over right arrow . (p) over right arrow calculations in the local spin density approximation. We show that high spin polarization can be maintained in these structures below certain values of the carrier concentrations. Full spin polarization is attained in the low carrier concentration regime for carrier concentrations in the DMS layer up to similar to 2.0 x 10(19) cm(-3) for Si and up to similar to 6.0 x 10(19) cm(-3) for SiC. Partial, but still important spin polarization can be achieved for all studied group-IV DMH, with the exception of Ge for carrier concentrations up to 6.0 x 10(19) cm(-3). The role played by the effective masses and the energy splitting of the spin-orbit split-off hole bands is also discussed throughout the paper.

Induced polarization, resistivity, and self-potential: a case history of contamination evaluation due to landfill leakage

This article compares the efficiency of induced polarization (IP) and resistivity in characterizing a contamination plume due to landfill leakage in a typical tropical environment. The resistivity survey revealed denser electrical current flow that induced lower resistivity values due to the high ionic content. The increased ionic concentration diminished the distance of the ionic charges close to the membrane, causing a decrease in the IP phenomena. In addition, the self-potential (SP) method was used to characterize the preferential flow direction of the area. The SP method proved to be effective at determining the flow direction; it is also fast and economical. In this study, the resistivity results were better correlated with the presence of contamination (lower resistivity) than the IP (lower chargeability) data.

Susceptibility of mosquito vectors to Dirofilaria immitis on Madeira Island, Portugal

Dirofilaria immitis (Leidy, 1856), an agent of heartworm disease, is an important parasite from both the veterinary standpoint and as a model to study human filariasis. It is a mosquito-borne filarial nematode which inhabits the right ventricle and pulmonary arteries of dogs. D. immitis is an important disease agent on Madeira Island with about 30% of dogs testing positive for this worm. Nevertheless, the vectors of this parasite in Madeira have never been studied, nor has the interaction between pathogen and vector, or the environmental variables that might influence heartworm transmission. Innate susceptibility to infection is only one component of vector competence, and field isolation of naturally infected mosquitoes has shown the capability of D. immitis to exploit a great diversity of vector species under natural conditions. The purpose of this work was to determine which mosquitoes are vectors of heartworm disease, the relation between population density and environment, and the association between immune response of the vector to the filarial parasite. Seasonal abundance of Culex theileri and Culex pipiens molestus was studied. Correlation and canonical correspondence analysis were performed using abundance data of these two species with selected weather variables, including mean temperature, relative humidity and accumulated precipitation. The most important factor determining Cx. theileri abundance was accumulated precipitation, while Cx. pipiens molestus abundance did not have any relationship with weather variables. Field studies were performed to verify whether Cx. theileri Theobald functions as a natural vector of D. immitis on Madeira Island, Portugal. Cx. theileri tested positive for D. immitis for the first time. The same study was made regarding Cx. p. molestus. Two abnormal L2 stage filarial worms were found in Malpighian tubules in field caught Cx. p. molestus. In the laboratory, two strains of Cx. p. molestus were studied for their susceptibility to D. immitis. None presented infective-stage larvae. Finally, because Cx. p. molestus is an autogenous mosquito, we evaluated the reproductive costs when this mosquito mounts an immune response against D. immitis in the absence of a blood meal. This mosquito showed an active immune response when inoculated intrathoracically with microfilariae (mf) of the heartworm. The ovaries from mosquitoes undergoing melanotic encapsulation developed more eggs than those which could not melanize the mf. This fact is contradictory with some previous studies of reproductive costs in Armigeres subalbatus and Ochlerotatus trivittatus, and it was the first time that an autogenous mosquito was used to study this subject.

Evaluation of the possible role of ants (Hymenoptera: Formicidae) as mechanical vectors of nematodes and protists

Os Nematoda e Protista podem ser transmitidos ao homem de diversas maneiras, mas pouca ênfase é dada para a transmissão mecânica por intermédio de formigas. Assim, esse trabalho procurou investigar a transmissão mecânica de ovos de Ascaris lumbricoides e cistos de Entamoeba coli pelos Formicidae. Através de experimentos com espécies mantidas em ninhos no laboratório (Tapinoma melanocephalum, Linepithema humile e Monomorium pharaonis) e com 17 espécies de formigas de uma área antropizada na região de Mogi as Cruzes (SP), foi possível constar que os ovos A. lumbricoides foram transportados por L. humile, tanto no campo (1 operária) como no laboratório (1 operária), por Camponotus rufipes (2), por Solenopsis saevissima (1) e por Acromyrmrex niger (1). em três operárias de C. rufipes foram encontrados cistos de E. coli. Apesar da baixa incidência de transporte, as três primeiras espécies pelo fato de viverem muito próximas ao ser humano, podem levar para dentro do ambiente domiciliar patógenos de Nematoda e Protista.

Geostatistical characterization of the spatial distribution of Xylella fastidiosa sharpshooter vectors on citrus

A distribuição espacial das espécies de cigarrinhas (Dilobopterus costalimai Young, Acrogonia sp. e Oncometopia facialis Signoret), vetoras da Xylella fastidiosa, agente causal da Clorose Variegada dos Citros, foi estudada com o uso da geoestatística. As avaliações foram feitas em um pomar comercial de laranja 'Pêra' (Citrus sinensis [L.] Osb.), objetivando estabelecer meios para melhor controle dos vetores e da doença. O monitoramento da ocorrência das cigarrinhas no pomar foi feito através de amostragens mensais, utilizando-se armadilhas adesivas amarelas de 3 x 5, distribuídas uniformemente em 50 pontos na área, dispostas em laranjeiras à altura de 1,5 m do solo e substituídas mensalmente. Acrogonia sp. foi a espécie prevalente nas amostragens. Os resultados possibilitaram ajustar modelos aos semivariogramas da distribuição espacial das três espécies no pomar estudado. Durante os três anos consecutivos de amostragem, as populações de Acrogonia sp., D. costalimai e O. facialis apresentaram modelos de distribuição agregada somente nos meses de verão, inverno e primavera, respectivamente, mostrando a necessidade de monitoramento constante desses vetores para reduzir a sua população em épocas favoráveis ao seu desenvolvimento. Através de parâmetros geoestatísticos foi possível calcular a área de agregação das cigarrinhas no pomar. A espécie Acrogonia sp. apresentou área média de agregação de 15.760 m², enquanto para O. facialis e D. costalimai foi possível constatar áreas médias de agregação de 11.555 m² e 10.980 m², respectivamente. Esses resultados indicaram que para um levantamento seguro de cigarrinhas é necessário pelo menos dispor de uma armadilha por hectare.

Uma abordagem para manipulação de informações geográficas utilizando Scalable Vectors Graphics

In this work, we propose a Geographical Information System that can be used as a tool for the treatment and study of problems related with environmental and city management issues. It is based on the Scalable Vector Graphics (SVG) standard for Web development of graphics. The project uses the concept of remate and real-time mar creation by database access through instructions executed by browsers on the Internet. As a way of proving the system effectiveness, we present two study cases;.the first on a region named Maracajaú Coral Reefs, located in Rio Grande do Norte coast, and the second in the Switzerland Northeast in which we intended to promote the substitution of MapServer by the system proposed here. We also show some results that demonstrate the larger geographical data capability achieved by the use of the standardized codes and open source tools, such as Extensible Markup Language (XML), Document Object Model (DOM), script languages ECMAScript/ JavaScript, Hypertext Preprocessor (PHP) and PostgreSQL and its extension, PostGIS

Case study: a 3D resistivity and induced polarization imaging from downstream a waste disposal site in Brazil

A contaminated site from a downstream municipal solid waste disposal site in Brazil was investigated by using a 3D resistivity and induced polarization (IP) imaging technique. This investigation purpose was to detect and delineate contamination plume produced by wastes. The area was selected based on previous geophysical investigations, and chemical analyses carried out in the site, indicating the presence of a contamination plume in the area. Resistivity model has successfully imaged waste presence (rho < 20 Omega m), water table depth, and groundwater flow direction. A conductive anomaly (rho < 20 Omega m) outside wastes placement was interpreted as a contamination plume. Chargeability model was also able to imaging waste presence (m > 31 mV/V), water table depth, and groundwater flow direction. A higher chargeability zone (m > 31 mV/V) outside wastes placement and following conductive anomaly was interpreted as a contamination plume. Normalized chargeability (MN = m/rho) confirmed polarizable zone, which could be an effect of a salinity increase (contamination plume), and the clay presence in the environment.

The self-polarization effect in Pb(Zr0.50Ti0.50)O-3 thin films with no preferential orientation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Prevention of experimental diabetes by Uncaria tomentosa extract: Th2 polarization, regulatory T cell preservation or both?

Ethnopharmacological relevance: Uncaria tomentosa (Willd.) DC (Rubiaceae) is a species native to the Amazon rainforest and surrounding tropical areas that is endowed with immunomodulatory properties and widely used around the world. In this study we investigated the immunomodulatory potential of Uncaria tomentosa (UT) aqueous-ethanol extract on the progression of immune-mediated diabetes.Materials and methods: C57BL/6 male mice were injected with MLDS (40 mg/kg) and orally treated with UT at 10-400 mg/kg during 21 days. Control groups received MLDS alone or the respective dilution vehicle. Pancreatic mononuclear infiltrate and beta-cell insulin content were analyzed by HE and immunohistochemical staining, respectively, and measured by digital morphometry. Lymphocyte immunophenotyping and cytokine production were determined by flow cytometry analysis.Results: Treating the animals with 50-400 mg/kg of UT caused a significant reduction in the glycemic levels, as well as in the incidence of diabetes. The morphometric analysis of insulitis revealed a clear protective effect. Animals treated with UT at 400 mg/kg presented a higher number of intact islets and a significant inhibition of destructive insulitis. Furthermore, a significant protection against the loss of insulin-secreting presented beta-cells was achieved, as observed by a careful immunohistochemical evaluation. The phenotypic analysis indicated that the groups treated with higher doses (100-400 mg/kg) presented CD4(+) and CD8(+) T-cell values similar to those observed in healthy animals. These same higher doses also increased the number of CD4(+)CD25(+)Foxp3(+) regulatory T-cells. Moreover, the extract modulated the production of Th1 and Th2, with increased levels of IL-4 and IL-5.Conclusions: The extract was effective to prevent the progression of immune-mediated diabetes by distinct pathways. (C) 2011 Elsevier B.V. All rights reserved.