Photosensitivity Color-Center Model for Ge-Doped Silica Preforms

A new photosensitivity physical model for Ge-doped silica preforms based on color-center photoreactions is presented. Simulation results are in close agreement with experimental results obtained by several condensed matter physics research groups working in this field, suggesting that the photoreactions of this model may, indeed, describe the physical processes involved in Ge-doped silica preform photosensitivity. The proposed photosensitivity model is defined by two differential equations that describe the temporal evolution of a set of color-center concentrations. The first is a modification of a very fast reversible reaction previously proposed by Fujimaki et al., where the reaction precursor has a different chemical structure (it is a neutral oxygen divacancy NODV unrelated to the previously proposed germanium lone pair center GLPC). The chemical structure of this precursor defect explains the generation of nonintrinsic neutral oxygen monovacancy ðNOMVÞ color centers. These centers are transformed into GeE0 defects by means of a second nonlinear reaction. This justifies the slow increase in the absorption peak experimentally measured at 6.3 eV, which had no satisfactory explanation.Ministerio de Ciencia y Tecnología TIC2001-2969-C03-0

Comuniquem amb la veu i les imatges dels centres educatius la innovació que promou el programa agenda 21 escolar de Barcelona

A l’acte de cloenda del curs 07/08 de l’Agenda 21Escolar de Barcelona s’ha presentat una nova eina de comunicació en forma de curtmetratge. Com a conclusió destaquem que, donat el seu nou format i enfoc, ha estat útil per mostrar als centres educatius un grapat d'experiències reals a partir d’un eix que vertebra les idees més innovadores, que motiva als centres que inicien per primer cop la seva A21E i que ens serveix per donar noves idees a les comissions coordinadores. A l’equip, ens ha permès crear espais de reflexió per identificar aquells aspectes que es consideren més importants del Programa i/o que cal reforçar. El procés de recollida d’experiències, les converses i les reflexions amb el professorat i l’alumnat durant el procés de gravació també ens ha permès avaluar l’assoliment dels objectius del Programa

Traçando mapas: a teoria histórico-cultural e as contribuições para a pesquisa com crianças e suas espacialidades

Este texto busca fazer uma reflexão sobre as pesquisas sistematizadas no campo da infância, tendo como enfoque principal as estratégias de pesquisas “com crianças”. O recorte ao qual nos dedicamos são as relações que as crianças estabelecem com o meio, tendo como foco principal as suas espacialidades. A partir das contribuições de pesquisas que se aportam em estratégias de natureza qualitativas e fundamentadas nos aportes da teoria históricas cultural, elege-se o conceito de vivência (perejivanie) como mote em torno do qual nossos trabalhos são desenvolvidos. Para isso, traça-se, inicialmente, a origem da pesquisa com base em paradigmas positivistas e evidenciam-se alguns caminhos que buscaram romper com essa perspectiva: os postulados etnográficos de Malinovky e Boas; o Interacionismo simbólico, cujo precursor é George Herbert Mead; a Etnometodologia de Harold Garfinkel; as contribuições de Marx e os princípios estabelecidos por Vigotski e seus colaboradores.</p

Toll-Like Receptor Polymorphisms and Susceptibility to Urinary Tract Infections in Adult Women

BACKGROUND:Although behavioral risk factors are strongly associated with urinary tract infection (UTI) risk, the role of genetics in acquiring this disease is poorly understood. METHODOLOGY/PRINCIPAL FINDINGS:To test the hypothesis that polymorphisms in Toll-like receptor (TLR) pathway genes are associated with susceptibility to UTIs, we conducted a population-based case-control study of women ages 18-49 years. We examined DNA variants in 9 TLR pathway genes in 431 recurrent cystitis (rUTI) cases, 400 pyelonephritis cases, and 430 controls with no history of UTIs. In the Caucasian subgroup of 987 women, polymorphism TLR4_A896G was associated with protection from rUTI, but not pyelonephritis, with an odds ratio (OR) of 0.54 and a 95% confidence interval (CI) of 0.31 to 0.96. Polymorphism TLR5_C1174T, which encodes a variant that abrogates flagellin-induced signaling, was associated with an increased risk of rUTI (OR(95%CI): 1.81 (1.00-3.08)), but not pyelonephritis. Polymorphism TLR1_G1805T was associated with protection from pyelonephritis (OR(95%CI): 0.53 (0.29-0.96)). CONCLUSIONS:These results provide the first evidence of associations of TLR5 and TLR1 variants with altered risks of acquiring rUTI and pyelonephritis, respectively. Although these data suggest that TLR polymorphisms are associated with adult susceptibility to UTIs, the statistical significance was modest and will require further study including validation with independent cohorts

3D Reconstruction of VZV Infected Cell Nuclei and PML Nuclear Cages by Serial Section Array Scanning Electron Microscopy and Electron Tomography

Varicella-zoster virus (VZV) is a human alphaherpesvirus that causes varicella (chickenpox) and herpes zoster (shingles). Like all herpesviruses, the VZV DNA genome is replicated in the nucleus and packaged into nucleocapsids that must egress across the nuclear membrane for incorporation into virus particles in the cytoplasm. Our recent work showed that VZV nucleocapsids are sequestered in nuclear cages formed from promyelocytic leukemia protein (PML) in vitro and in human dorsal root ganglia and skin xenografts in vivo. We sought a method to determine the three-dimensional (3D) distribution of nucleocapsids in the nuclei of herpesvirus-infected cells as well as the 3D shape, volume and ultrastructure of these unique PML subnuclear domains. Here we report the development of a novel 3D imaging and reconstruction strategy that we term Serial Section Array-Scanning Electron Microscopy (SSA-SEM) and its application to the analysis of VZV-infected cells and these nuclear PML cages. We show that SSA-SEM permits large volume imaging and 3D reconstruction at a resolution sufficient to localize, count and distinguish different types of VZV nucleocapsids and to visualize complete PML cages. This method allowed a quantitative determination of how many nucleocapsids can be sequestered within individual PML cages (sequestration capacity), what proportion of nucleocapsids are entrapped in single nuclei (sequestration efficiency) and revealed the ultrastructural detail of the PML cages. More than 98% of all nucleocapsids in reconstructed nuclear volumes were contained in PML cages and single PML cages sequestered up to 2,780 nucleocapsids, which were shown by electron tomography to be embedded and cross-linked by an filamentous electron-dense meshwork within these unique subnuclear domains. This SSA-SEM analysis extends our recent characterization of PML cages and provides a proof of concept for this new strategy to investigate events during virion assembly at the single cell level

Identification of Reproduction-Specific Genes Associated with Maturation and Estrogen Exposure in a Marine Bivalve Mytilus edulis

Background: While it is established that vertebrate-like steroids, particularly estrogens (estradiol, estrone) and androgens (testosterone), are present in various tissues of molluscs, it is still unclear what role these play in reproductive endocrinology in such organisms. This is despite the significant commercial shellfishery interest in several bivalve species and their decline. Methodology/Principal Findings: Using suppression subtraction hybridisation of mussel gonad samples at two stages (early and mature) of gametogenesis and (in parallel) following controlled laboratory estrogen exposure, we isolate several differentially regulated genes including testis-specific kinases, vitelline lysin and envelope sequences. Conclusions: The differentially expressed mRNAs isolated provide evidence that mussels may be impacted by exogenous estrogen exposure