155 research outputs found

    Universality Classes for Interface Growth with Quenched Disorder

    Full text link
    We present numerical evidence that there are two distinct universality classes characterizing driven interface roughening in the presence of quenched disorder. The evidence is based on the behavior of λ\lambda, the coefficient of the nonlinear term in the growth equation. Specifically, for three of the models studied, λ\lambda \rightarrow \infty at the depinning transition, while for the two other models, λ0\lambda \rightarrow 0.Comment: 11 pages and 3 figures (upon request), REVTeX 3.0, (submitted to PRL

    Areas of natural occurrence of melipona scutellaris Latreille, 1811(Hymenoptera: Apidae) in the state of Bahia, Brazil.

    Get PDF
    The bee Melipona scutellaris is considered the reared meliponine species with the largest distribution in the North and Northeast regions of Brazil, with records from the state of Rio Grande do Norte down to the state of Bahia. Considering the importance of this species in the generation of income for family agriculture and in the preservation of areas with natural vegetation, this study aimed at providing knowledge on the distribution of natural colonies of M. scutellaris in the state of Bahia. Literature information, interviews with stinglessbee beekeepers, and expeditions were conducted to confirm the natural occurrence of the species. A total of 102 municipalities showed records for M. scutellaris, whose occurrence was observed in areas ranging from sea level up to 1,200-meter height. The occurrence of this species in the state of Bahia is considered to be restricted to municipalities on the coastal area and the Chapada Diamantina with its rainforests. Geographic coordinates, elevation, climate and vegetation data were obtained, which allowed a map to be prepared for the area of occurrence in order to support conservation and management policies for the species

    Genetic diversity of Xanthomonas citri subsp. citri in citrus orchards in northwest Paraná state, Brazil

    Get PDF
    Xanthomonas citri subsp. citri, which causes Asiatic citrus canker (ACC), is an important pathogen of citrus in Brazil and elsewhere. The genetic diversity of X. citri subsp. citri pathotype ‘A’ has not been studied in Brazil at a local scale (up to 300 km). Forty isolates were sampled from lesions of ACC on citrus in three orchards in Paraná state, Brazil. Twelve minisatellite markers were used to characterize the genetic diversity of the isolates. An Unweighted Paired Group Method of Arithmetic Averages tree was used for identifying unique multilocus haplotypes but there was no association between haplotypes and source locations. An analysis of molecular variance among populations showed that 98% of the variance was accounted for within the populations, and only 2% was accounted for among populations. Differences among populations was not significant (Φ=0.018, P=0.2). The relatively high, yet uniform, genetic diversity among isolates and low degree of spatial differentiation between populations of X. citri subsp. citri suggests that the populations in Paraná state have a common origin and strong historical epidemiological links

    APOIO À DECISÃO PARA A PROTEÇÃO INTEGRADA NO COMBATE A Tuta absoluta EM TOMATE HORTOINDUSTRIAL

    Get PDF
    A traça-do-tomateiro é atualmente uma praga-chave do tomate para indústria, na região do Ribatejo. A sua presença foi detectada em 2010, tendo causado prejuízos significativos na campanha de 2011. O objetivo deste projeto é criar ferramentas para a tomada de decisão no âmbito da proteção desta cultura contra esta praga. Durante o ano de 2013, procedeu-se à monitorização semanal de adultos de T. absoluta com recurso a armadilhas com feromona sexual, e à observação visual em 25 a 50 plantas, de acordo com o estado fenológico da cultura. O material entomológico foram analisadas, posteriormente, em laboratório para deteção de parasitismo. Além de avaliar a intensidade de ataque, identificaram-se fatores de risco prévio, para construção de mapas de risco de apoio à tomada de decisão para a limitação da praga como culturas vizinhas e respetivas datas de colheita. Os dados preliminares não apresentaram uma correlação entre o número de machos adultos capturados e o número de larvas presentes na cultura, pelo que a estimativa de risco baseada apenas na contagem de machos adultos não parece ser suficiente para a tomada de decisão. Verificaram-se dificuldades no combate à praga devido a razões de ordem estrutural (e.g. posse da terra, hospedeiros alternativos na vizinhança) e a lacunas no conhecimento da sua bioecologia

    Evaluation of the impact of iPSC differentiation protocols on transcriptomic signatures.

    Get PDF
    Human induced pluripotent stem cells (iPSC) have the potential to produce desired target cell types in vitro and allow for the high-throughput screening of drugs/chemicals at population level thereby minimising the cost of drug discovery and drug withdrawals after clinical trials. There is a substantial need for the characterisation of the iPSC derived models to better understand and utilise them for toxicological relevant applications. In our study, iPSC (SBAD2 or SBAD3 lines obtained from StemBANCC project) were differentiated towards toxicologically relevant cell types: alveolar macrophages, brain capillary endothelial cells, brain cells, endothelial cells, hepatocytes, lung airway epithelium, monocytes, podocytes and renal proximal tubular cells. A targeted transcriptomic approach was employed to understand the effects of differentiation protocols on these cell types. Pearson correlation and principal component analysis (PCA) separated most of the intended target cell types and undifferentiated iPSC models as distinct groups with a high correlation among replicates from the same model. Based on PCA, the intended target cell types could also be separated into the three germ layer groups (ectoderm, endoderm and mesoderm). Differential expression analysis (DESeq2) presented the upregulated genes in each intended target cell types that allowed the evaluation of the differentiation to certain degree and the selection of key differentiation markers. In conclusion, these data confirm the versatile use of iPSC differentiated cell types as standardizable and relevant model systems for in vitro toxicology

    Water-use strategies in two co-occurring Mediterranean evergreen oaks: surviving the summer drought

    Get PDF
    In the Mediterranean evergreen oakwoodlands of southern Portugal, the main tree species are Quercus ilex ssp. rotundifolia Lam. (holm oak) and Quercus suber L. (cork oak). We studied a savannah-type woodland where these species coexist, with the aim of better understanding the mechanisms of tree adaptation to seasonal drought. In both species, seasonal variations in transpiration and predawn leaf water potential showed a maximum in spring followed by a decline through the rainless summer and a recovery with autumn rainfall. Although the observed decrease in predawn leaf water potential in summer indicates soil water depletion, trees maintained transpiration rates above 0.7 mm day–1 during the summer drought. By that time, more than 70% of the transpired water was being taken from groundwater sources. The daily fluctuations in soil water content suggest that some root uptake of groundwater was mediated through the upper soil layers by hydraulic lift. During the dry season, Q. ilex maintained higher predawn leaf water potentials, canopy conductances and transpiration rates than Q. suber. The higherwater status of Q. ilexwas likely associated with their deeper root systems compared with Q. suber. Whole-tree hydraulic conductance and minimum midday leaf water potential were lower in Q. ilex, indicating that Q. ilex was more tolerant to drought than Q. suber. Overall, Q. ilex seemed to have more effective drought avoidance and drought tolerance mechanisms than Q. suber
    corecore