Um Novo Conceito de Interrogação Por Padrões Speckles para Sensores de Pressão Aplicados na Indústria de Petróleo e em Áreas Classificadas

Equipamentos elétricos instalados em áreas classificadas necessitam ser protegidos de alguma forma, para que eles não iniciem uma explosão devido a curto-circuito ou mesmo por provocar alta temperatura, devendo atender normas nacionais e internacionais. Um dos sensores mais utilizados em processos na indústria é o de pressão, que também pode ser utilizado para inferir nível, vazão e temperatura. Nesse contexto, a utilização da fibra óptica com uso de laser de baixa potência se torna bastante atrativa para leitura de pressão. A fibra óptica associada a utilização de laser de baixa potência, pode reduzir os riscos de explosão em áreas classificadas sem necessidade de proteção requerida em norma. Para realizar a medida de pressão com fibra óptica nesse trabalho, um laser de baixa potência (da ordem de mW) foi acoplado através de uma fibra óptica polimérica (POF) em substituição ao ponteiro de um manômetro de Bourdon convencional. A luz é propagada através da fibra e refletida na área rugosa, que gera padrões speckles que contém as informações do ângulo de giro. O speckle é uma imagem de aspecto granular que se forma quando um feixe de luz coerente atravessa um meio (nesse caso, a fibra multimodo) que possui algumas centenas de modos de propagação e apresenta variações no índice de refração. A imagem de saída da fibra multimodo acoplada ao manômetro é capturada a fim de medir o deslocamento angular da área observada, que deve ser substituída pelo ponteiro. O estudo e interpretação dos padrões speckles gerados experimentalmente foram feitos por software, correlacionando as imagens com os valores do manômetro de referência. Uma rotina de filtro morfológico eliminou previamente os ruídos da imagem, devido a vibrações produzidas pelo próprio meio onde o protótipo foi instalado. Com isto, a imagem sofreu menor variação do meio para então ser processada de duas formas: primeiro foi aplicada a técnica de Wiener-Khintchine, adquirindo os picos da correlação cruzada entre as imagens do vídeo produzido. Após a aplicação dessa técnica, também foi desenvolvida uma rede neural com valores de erro quadrático médio tais que viabilizaram a sua aplicação prática. Os resultados obtidos através da técnica de Wiener-Khintchine com a aplicação da transformada rápida de fourier foram suficientes para mostrar a dependência com a variação de pressão, mas as leituras realizadas ainda foram inviáveis para a aplicação do modelo em campo. Os valores lidos não tinham produzido resolução suficiente, pois foram de 18 graus com variação de 3; 2%. Após o desenvolvimento da rede neural, utilizando algoritmo feed-forward backpropagation (AFFWBP) multicamada, foi possível atingir resolução para aplicação em campo, com erros menores que 3 graus

Rhizobacteria promoting growth and defense in rice plants against Magnaporthe oryzae.

This study investigated the effect of PGPR in promoting growth of rice roots and suppressing leaf blast (Magnaporthe oryzae)

Near-infrared observations of galaxies in Pisces-Perseus: I. H-band surface photometry of 174 spirals

We present near-infrared, H-band (1.65 um), surface photometry of 174 spiral galaxies in the area of the Pisces-Perseus supercluster. The images, acquired with the ARNICA camera mounted on various telescopes, are used to derive radial profiles of surface brightness, ellipticities, and position angles, together with global parameters such as H-band magnitudes and diameters. The mean relation between H-band isophotal diameter D_{21.5} and the B-band D_{25} implies a B-H color of the outer disk bluer than 3.5; moreover, D_{21.5}/D_{25} depends on (global) color and absolute luminosity. The correlations among the various photometric parameters suggest a ratio between isophotal radius D_{21.5}/2 and disk scale length of about 3.5 and a mean disk central brightness of 17.5 H-mag arcsec^{-2}. We confirm the trend of the concentration index C_{31} with absolute luminosity and, to a lesser degree, with morphological type. We also assess the influence of non-axisymmetric structures on the radial profiles and on the derived parameters.Comment: 10 pages, 11 postscript figures (one table and one figure are available only at the CDS); to be published on A&A

Signatures of Galaxy-Cluster Interactions: Spiral Galaxy Rotation Curve Asymmetry, Shape, and Extent

The environmental dependencies of the characteristics of spiral galaxy rotation curves are studied in this work. We use our large, homogeneously collected sample of 510 cluster spiral galaxy rotation curves to test the claim that the shape of a galaxy's rotation curve strongly depends on its location within the cluster, and thus presumably on the strength of the local intracluster medium and on the frequency and strength of tidal interactions with the cluster and cluster galaxies. Our data do not corroborate such a scenario, consistent with the fact that Tully-Fisher residuals are independent of galaxy location within the cluster; while the average late-type spiral galaxy shows more rise in the outer parts of its rotation curve than does the typical early-type spiral galaxy, there is no apparent trend for either subset with cluster environment. We also investigate as a function of cluster environment rotation curve asymmetry and the radial distribution of H II region tracers within galactic disks. Mild trends with projected cluster-centric distance are observed: (i) the (normalized) radial extent of optical line emission averaged over all spiral galaxy types shows a 4%+/-2% increase per Mpc of galaxy-cluster core separation, and (ii) rotation curve asymmetry falls by a factor of two between the inner and outer cluster for early-type spirals (a negligible decrease is found for late-type spirals). Such trends are consistent with spiral disk perturbations or even the stripping of the diffuse, outermost gaseous regions within the disks as galaxies pass through the dense cluster cores.Comment: 17 pages; to appear in the April 2001 Astronomical Journa

The Gut Commensal Bacteroides thetaiotaomicron Exacerbates Enteric Infection through Modification of the Metabolic Landscape

SummaryThe enteric pathogen enterohemorrhagic Escherichia coli (EHEC) causes severe diarrhea, but the influence of the gut microbiota on EHEC infection is largely unknown. A predominant member of the microbiota, Bacteroides thetaiotaomicron (Bt), is resident at EHEC attachment sites. We show that Bt enhances EHEC virulence gene expression through the transcription factor Cra, which is functionally sensitive to sugar concentrations. This enhanced virulence accompanies increased formation of attaching and effacing (AE) lesions requisite for EHEC colonization. Infection with Citrobacter rodentium, a natural mouse pathogen homologous to EHEC, in Bt-reconstituted mice results in increased gut permeability along with exacerbated host pathology and mortality compared to mice deplete of microflora. Bt modifies the metabolite environment at infection sites, increasing metabolites involved in gluconeogenesis, with stark increases in succinate, which can be sensed by Cra. Our findings suggest that microbiota composition affects disease outcome and may explain links between microbiota composition and disease susceptibility

VIP: An Experiment to Search for a Violation of the Pauli Exclusion Principle

The Pauli Exclusion Principle is a basic principle of Quantum Mechanics, and its validity has never been seriously challenged. However, given its fundamental standing, it is very important to check it as thoroughly as possible. Here we describe the VIP (VIolation of the Pauli exclusion principle) experiment, an improved version of the Ramberg and Snow experiment (E. Ramberg and G. Snow, {\it Phys. Lett. B} {\bf 238}, 438 (1990)); VIP has just completed the installation at the Gran Sasso underground laboratory, and aims to test the Pauli Exclusion Principle for electrons with unprecedented accuracy, down to $\beta^2/2 \approx 10^{-30} - 10^{-31}$. We report preliminary experimental results and briefly discuss some of the implications of a possible violation.Comment: Plenary talk presented by E. Milotti at Meson 2006, Cracow, 9-13 June 200

New experimental limit on the Pauli Exclusion Principle violation by electrons

The Pauli Exclusion Principle (PEP) is one of the basic principles of modern physics and, even if there are no compelling reasons to doubt its validity, it is still debated today because an intuitive, elementary explanation is still missing, and because of its unique stand among the basic symmetries of physics. The present paper reports a new limit on the probability that PEP is violated by electrons, in a search for a shifted K$_\alpha$ line in copper: the presence of this line in the soft X-ray copper fluorescence would signal a transition to a ground state already occupied by 2 electrons. The obtained value, ${1/2} \beta^{2} \leq 4.5\times 10^{-28}$, improves the existing limit by almost two orders of magnitude.Comment: submitted to Phys. Lett.