Polymer induced condensation of dna supercoils

Macromolecular crowding is thought to be a significant factor driving DNA condensation in prokaryotic cells. Whereas DNA in prokaryotes is supercoiled, studies on crowding-induced DNA condensation have so far focused on linear DNA. Here we compare DNA condensation by poly(ethylene oxide) for supercoiled and linearized pUC18 plasmid DNA. It is found that supercoiling has only a limited influence on the critical amount of PEO needed to condense plasmid DNA. In order to pack DNA supercoils in condensates, it seems inevitable that they must be deformed in one way or another, to facilitate dense packing of DNA. Analytical estimates and Monte Carlo simulations indicate that packing of DNA supercoils in condensates is most likely facilitated by a decrease of the superhelical diameter rather than by unwinding of the supercoil

Educação e renda : um estudo comparativo sobre os retornos de escolaridade no Estado de Goiás e no Distrito Federal

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Administração, Ciências Contábeis e Economia, Departamento de Economia, Programa de Pós-Graduação em Economia, Mestrado Profissional em Gestão Econômica de Finanças Públicas, 2013.O objetivo da presente pesquisa é analisar o papel da educação na determinação da renda dos indivíduos, usando como ilustração dados do Estado de Goiás e do Distrito Federal. Esse trabalho parte da hipótese que maiores níveis de escolarização contribuem mais para renda do indivíduo. Além da escolarização, foram incluídas no modelo outras variáveis socioeconômicas, tais como sexo, cor, situação sindical, para diminuir distorções que possam afetar o modelo. A amostra foi selecionada a partir da PNAD (Pesquisa Nacional por Amostra a Domicílio), do ano de 2009, e constitui-se de um total de 10371 indivíduos que declaram ter renda, sendo 6359 do Estado de Goiás e 4312 do Distrito Federal. Assim, foram estimados os retornos à renda baseados na equação minceriana dos salários. Os resultados indicam que, em ambas as Unidades da Federação, o impacto da educação na renda aumenta com o nível de escolarização, e prevalece sobre as outras variáveis incluídas no modelo. ______________________________________________________________________________ ABSTRACTThe goal of this research is to analyze the role of education in determining the income of individuals, using as an illustration, dates of the State of Goias and the Federal District. This work starts from the hypothesis that higher levels of education contribute more to individual income. Beyond the schooling, were included in the model other socioeconomic variables, such as gender, race, union status, to reduce distortions that may affect the model. The sample was selected from the PNAD (Pesquisa Nacional por Amostra a Domicílio), of 2009, and consists of a total of 10371 individuals who claim to have income, being 6359 from State of Goias and, 4312 from Federal District. Thus, we estimated the returns to income based on Mincerian wage equation. The results indicate that, in both of federation units, the impact of education in income increases with the level of schooling, and prevails over the other variables included in the model

Clusters and the context for competitive advantage : a strategic analysis of the Engineering & Tooling cluster

Mestrado em Gestão e Estratégia IndustrialA presente dissertação ilustra uma aplicação empírica do Modelo do Diamante de Porter (1990, 2004) recorrendo ao método de modelação de equações estruturais com base nos mínimos quadrados parciais (PLS-SEM; Wold, 1975, 1982), com vista a avaliar os efeitos da envolvente microeconómica na vantagem competitiva das empresas e do apoio governamental na melhoria desta envolvente. A investigação adota um design de triangulação simultânea e toma como unidade de análise as empresas do cluster Engineering & Tooling. Os resultados da análise de equações estruturais (path analysis) decorrem de um número total de 168 de respostas obtidas através de um questionário dirigido às empresas do cluster, os quais foram subsequentemente triangulados com dados secundários e entrevistas realizadas com vários intervenientes do cluster. Estes resultados revelam um efeito positivo tanto das indústrias relacionadas e de suporte, como do contexto para a estratégia e rivalidade empresarial, e das condições de fatores ao nível do cluster na vantagem competitiva das empresas. Também foi demonstrado que a ação do governo tem um efeito positivo nos quatro fatores determinantes do Modelo do Diamante. Contrariamente, as perceções dos respondentes não suportam um efeito positivo das condições da procura do cluster na vantagem competitiva empresarial. Os efeitos positivos e negativos da envolvente do cluster Engineering & Tooling na vantagem competitiva das empresas realçam o papel catalisador do governo e da ação coletiva na melhoria das condições do cluster.This dissertation illustrates an empirical application of Porter's (1990, 2004) Diamond Model using the Partial Least Squares Structural Equation Modelling (PLS-SEM; Wold, 1975, 1982) method in order to assess the effects of the microeconomic business environment on firms' competitive advantage and the government's supportive role in improving such an environment. It follows a concurrent triangulation design and takes firms in the Portuguese Engineering & Tooling cluster as the basic unit of analysis. The findings from the path analysis derive from a total number of 168 questionnaire responses obtained from firms in the cluster, which were subsequently triangulated with secondary data and interviews conducted with several cluster stakeholders. These findings reveal a positive effect of the related and supporting industries, the context for firm strategy and rivalry, and the factor (input) conditions at the cluster level on firms' competitive advantage. Government action has also been shown to have a positive effect on the four determinants of the Diamond Model. Conversely, respondents' perceptions do not support a positive effect of the demand conditions at the cluster level on firms' competitive advantage. The positive and negative effects of the Engineering & Tooling cluster's environment on the competitive edge of firms highlight the catalytic roles of the government and collective action in cluster upgrading.info:eu-repo/semantics/publishedVersio

Condensation of Vortex-Strings: Effective Potential Contribution Through Dual Actions

Topological excitations are believed to play an important role in different areas of physics. For example, one case of topical interest is the use of dual models of quantum cromodynamics to understand properties of its vacuum and confinement through the condensation of magnetic monopoles and vortices. Other applications are related to the role of these topological excitations, nonhomogeneous solutions of the field equations, in phase transitions associated to spontaneous symmetry breaking in gauge theories, whose study is of importance in phase transitions in the early universe, for instance. Here we show a derivation of a model dual to the scalar Abelian Higgs model where its topological excitations, namely vortex-strings, become manifest and can be treated in a quantum field theory way. The derivation of the nontrivial contribution of these vacuum excitations to phase transitions and its analogy with superconductivity is then made possible and they are studied here.Comment: 7 pages. Based on a talk given by R. O. Ramos at the Infrared QCD in Rio conference, Rio de Janeiro, Brazil, June 5-9, 200

Provenance does matter: links between winter trophic segregation and the migratory origins of European robins

Amongst migratory species, it is common to find individuals from different populations or geographical origins sharing staging or wintering areas. Given their differing life histories, ecological theory would predict that the different groups of individuals should exhibit some level of niche segregation. This has rarely been investigated because of the difficulty in assigning migrating individuals to breeding areas. Here, we start by documenting a broad geographical gradient of hydrogen isotopes (δ2H) in robin Erithacus rubecula feathers across Europe. We then use δ2H, as well as wing-tip shape, as surrogates for broad migratory origin of birds wintering in Iberia, to investigate the ecological segregation of populations. Wintering robins of different sexes, ages and body sizes are known to segregate between habitats in Iberia. This has been attributed to the despotic exclusion of inferior competitors from the best patches by dominant individuals. We find no segregation between habitats in relation to δ2H in feathers, or to wing-tip shape, which suggests that no major asymmetries in competitive ability exist between migrant robins of different origins. Trophic level (inferred from nitrogen isotopes in blood) correlated both with δ2H in feathers and with wing-tip shape, showing that individuals from different geographic origins display a degree of ecological segregation in shared winter quarters. Isotopic mixing models indicate that wintering birds originating from more northerly populations consume more invertebrates. Our multi-scale study suggests that trophic-niche segregation may result from specializations (arising in the population-specific breeding areas) that are transported by the migrants into the shared wintering grounds

Lasso Estimation of an Interval-Valued Multiple Regression Model

A multiple interval-valued linear regression model considering all the cross-relationships between the mids and spreads of the intervals has been introduced recently. A least-squares estimation of the regression parameters has been carried out by transforming a quadratic optimization problem with inequality constraints into a linear complementary problem and using Lemke's algorithm to solve it. Due to the irrelevance of certain cross-relationships, an alternative estimation process, the LASSO (Least Absolut Shrinkage and Selection Operator), is developed. A comparative study showing the differences between the proposed estimators is provided

Afterword

info:eu-repo/semantics/publishedVersio