Homogeneous abundance analysis of dwarf, subgiant and giant FGK stars with and without giant planets

We have analyzed high-resolution and high signal-to-noise ratio optical spectra of nearby FGK stars with and without detected giant planets in order to homogeneously measure their photospheric parameters, mass, age, and the abundances of volatile (C, N, and O) and refractory (Na, Mg, Si, Ca, Ti, V, Mn, Fe, Ni, Cu, and Ba) elements. Our sample contains 309 stars from the solar neighborhood (up to the distance of 100 pc), out of which 140 are dwarfs, 29 are subgiants, and 140 are giants. The photospheric parameters are derived from the equivalent widths of Fe I and Fe II lines. Masses and ages come from the interpolation in evolutionary tracks and isochrones on the HR diagram. The abundance determination is based on the equivalent widths of selected atomic lines of the refractory elements and on the spectral synthesis of C_2, CN, C I, O I, and Na I features. We apply a set of statistical methods to analyze the abundances derived for the three subsamples. Our results show that: i) giant stars systematically exhibit underabundance in [C/Fe] and overabundance in [N/Fe] and [Na/Fe] in comparison with dwarfs, a result that is normally attributed to evolution-induced mixing processes in the envelope of evolved stars; ii) for solar analogs only, the abundance trends with the condensation temperature of the elements are correlated with age and anticorrelated with the surface gravity, which is in agreement with recent studies; iii) as in the case of [Fe/H], dwarf stars with giant planets are systematically enriched in [X/H] for all the analyzed elements, except for O and Ba (the former due to limitations of statistics), confirming previous findings in the literature that not only iron has an important relation with the planetary formation; and iv) giant planet hosts are also significantly overabundant for the same metallicity when the elements from Mg to Cu are combined together.Comment: 20 pages, 16 figures, 8 table

Additions to the knowledge of the Chactidae of Brazilian Amazonia (Arachnida: Scorpiones)

An account of the chactid scorpions of Brazilian Amazonia is given and a list of all recorded scorpions in the region is provided. Broteochactas skuki n.sp. is described. The hitherto unknown male of Brotheas paraensis SIMON is described, and one female of Guyanochactas gougei (VELLARD) new combination is described. The known distribution of Brotheas amazonicus LOURENCO, 1988 is expanded to Rondonia and Roraima States

Uniform polarization scattering with fiber-coil-based polarization controllers

A detailed study of fiber-coil-based polarization controllers (PCs) is performed. First, a method to deterministically calculate the PC configuration in order to transform between any two states of polarization is presented. In a second stage, the case in which the configuration angles are randomly changed is studied. The cases of a single PC and of the system obtained with the concatenation of several PCs are analyzed. For both cases, a general expression for the variance of the Stokes parameters is obtained. Using this expression, it is demonstrated that it is possible to achieve uniform polarization scattering using a concatenation of fiber-coil-based PCs. Finally, it is shown that fiber-coil-based PC's can be used to emulate both, first- and second-order polarization- mode dispersions

Ferramenta de simulação para análise espectral de redes de Bragg

As redes de Bragg (FBG) tornaram-se componentes importantes na redes de comunicações ópticas, pois permitem a realização de várias operações sem a necessidade de conversão opto-electrónica. Este artigo descreve uma ferramenta de software para simulação e caracterização de redes de Bragg por nós inteiramente concebida. A interface gráfica foi programada utilizando o ambiente GUIDE do Matlab. É assim possível analisar um leque variado de FBGs, tendo em consideração os efeitos secundários provocados pela variação do índice de refracção médio, durante o processo de fabrico

A comparison of the Normal and Laplace distributions in the models of fuzzy probability distribution for portfolio selection

The propose of this work is applied the fuzzy Laplace distribution on a possibilistic mean-variance model presented by Li et al which appliehe fuzzy normal distribution. The theorem necessary to introduce the Laplace distribution in the model was demonstrated. It was made an analysis of the behavior of the fuzzy normal and fuzzy Laplace distributions on the portfolio selection with VaR constraint and risk-free investment considering real data. The results showns that were not difference in assets selection and in return rate, however, There was a change in the risk rate, which was higher in the Laplace distribution than in the normal distribution

Dripping Faucet Dynamics Clarified by an Improved Mass-Spring Model

An improved mass-spring model for a dripping faucet is presented. The model is constructed based on the numerical results which we recently obtained from fluid dynamical calculations. Both the fluid dynamical calculations and the present mass-spring model exhibit a variety of complex behavior including transition to chaos in good agreement with experiments. Further, the mass-spring model reveals fundamental dynamics inherent in the dripping faucet system.Comment: 17 pages, 17 figure

As forças armadas e o desenvolvimento científico e tecnológico do país

301 p.Trata-se de um documento que fala sobre as questões de desenvolvimento científicas e tecnológicas do país. Faz parte da coleção sobre o pensamento brasileiro a respeito da defesa e da segurança. Esse terceiro volume foca na questão da indústria da defesa e sobre o papel da ciência e da tecnologia junto a soberania da defesa nacional

Reflexões sobre defesa e segurança: um estratégia para o Brasil

221 p.Trata-se de um documento que fala sobre a evolução da defesa e da segurança do Brasil. Faz parte da coleção sobre o pensamento brasileiro a respeito da defesa e da segurança. Esse primeiro volume foca na questão da evolução desse pensamento e sobre os conceitos de segurança e defesa do governo