Lítio e rotação nas estrelas análogas solares: análise teórica das observações

The projected rotational velocity together with lithium abundance and the onset of the dilution by the deepening in mass of the convective envelope provide a key tool to investigate the so far poorly understood processes at work in stellar interiors of solar-analog stars. To investigate the link between abundances, convection and rotational velocities in solar-analog G dwarf stars, we study a bona fide sample of 118 selected solar-analog G dwarf stars presenting measured lithium abundances, rotational velocities, and fundamental parameters together with computed evolutionary tracks (Toulouse-Geneva code) for a range of stellar masses around 1 M and metallicity consistent with the solar-analog range. The aim of this work is to build up an evolution of lithium and rotation as a function of stellar age, mass, effective temperature, and convection. We analyze the evolutionary status of the sample of 118 solar-analog G dwarf in the HR diagram based on Hipparcos data and using a grid of stellar models in the effective temperature and mass range of the solar-analog stars. We discuss the deepening (in mass) of the convective envelope and the influence on the Li abundances and projected rotational velocities. We determined the stellar mass and the mass of the convective envelope for a bona fide sample of 118 selected solar-analog G dwarf and checked the evolutionary link between the rotational velocity, lithium abundance, and the deepening of the convective envelope. Fast rotators (vsini 6 km s��1) are also stars with high Li content. Slow rotators present a wide range of values of log n(Li). Our results shed new light on the lithium and rotational behavior in G dwarf stars. We confirmed the presence of a large Li abundance spread among the solar-analog stars and concluded that the solar twins probably share a similar mixing history with the Sun

Recuperação de sinais esparsos. Investigação numérica sobre a quantidade de medidas necessárias para recuperar um sinal esparso

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

A distribuição F generalizada para selecionar modelos de sobrevivência com fração de cura

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Caracterização de minerais pesados ao longo do Rio Piranhas-Açu/RN distribuição e proveniência

This dissertation deals with the characterization, distribution and provenience of heavy minerals along the Piranhas-Açu River, from the City of Parelhas (Seridó River) to your mouth at the City of Macau-RN. Many heavy minerals species were recorded in this study: clinoamphibole, epidote (including zoisite), garnet, sillimanite, tourmaline, staurolite, andalusite, zircon, rutile, augite, ilmenite, hematite and magnetite. Major transparent minerals, those forming more than 5% of some assemblages, are hornblende, epidote, tourmaline, staurolite and zircon. Predominant opaque mineral is ilmenite. Six assemblages were identified along the river: (i) Garnet-hornblende-tourmaline with sillimanite, when cutting rocks of the Seridó Formation; (ii) Hornblende-garnet-zircon, when crossing rocks of the Caicó gnaisse-migmatitic Complex; (iii) Hornblende-zircon-epidote-staurolite, when draining rocks of the Jucurutu Formation; (iv) Hornblende-zircon-epidote, when cutting rocks of the Açu Formation; (v) Hornblende-zircon-staurolite, on the lowermost Açu River, when crossing limestones of the Jandaíra Formation and (vi) Zircon-tourmaline-staurolite in the Açu River mouth (Cenozoic rocks) where coastal process dominate. Mineral ratios that reflect differences in grain shape, density, and selective chemical decomposition were used in an attempt to isolate the effects of source and process as controls of mineral variability. Reworking of the sediments was regionally effective in selective sorting; the more equant minerals (e.g. epidote) and heavier minerals (e.g. opaques) had a higher probability of being selected for permanent deposition during reworking. The processes of selective decomposition stand out at the river mouth. A priori knowledge of provenance, associated with the assemblage distribution and effects of process were utilized to the interpretations, that points to the follow provenances: hornblende comes from micashists of the Seridó Formation, orthognaisses and amphibolites of the Caico Complex, paragnaisses and paranphibolites of the Jucurutu Formation and granites intrusions; epidote comes from paragnaisses and calciosilicatics of the Jucurutu Formation, granites intrusions (-Npy3al/ca and -Npy3mz, gravels deposits and Açu Formation; Andalusite and staurolite come from the Seridó Formation; Sillimanite, tourmaline and garnet come from micashists of the Seridó Formation, as well as from quartzites of the Equador Formation; Zircon comes from Precambrian rocks (pink and prismatic zircon) and from sediments of several cycles (round zircon); Opaques come from all rocks cutted for the Piranhas-Açu River; Rutile comes from metamorphic rocks, in general; Augite comes from the Ceará-Mirim, Serra do Cuó and Macau volcanisms. The texture of gravels deposits reveals a sediment transport mechanisms by traction-current processes, together with a diagenetic clay matrix suggests a hot-humid environments for deposition. The presence of unstable heavy minerals assemblages, as well as pebbles of different composition and degrees of rounding and esfericity, indicate more than one source. The occurrence of calcio/alkaline granites suites, in areas closed to the gravel deposits, suggests that these intrusions are the main source of sediments. This could explain for instance, the significant amounts of epidote and presence of unstable heavy minerals (e.g. hornblende). The analyses of heavy minerals also show significante variability between the modern (Piranhas-Açu) and ancestral (Açu Formation) river sediments. In general, these variations reflect relatively higher unstable and lower stable heavy minerals contents of the modern Piranhas-Açu sediments. The absence of significant compositional differences probably reflects uniform weathering conditions

Distribuição socioespacial dos fatores dinâmicos da população na Região Metropolitana de Natal

The Metropolitan Region of Natal, like other metropolitan regions in Brazil, was marked by intense and rapid urbanization of the country occurred only in the second half of the twentieth century, coinciding with the process of consolidation of the industry in the country, resulting in serious urban social problems, such as the increase in slums, lack of infrastructure and this increase in violence in urban centers. When enters the reality of the metropolitan region, assessing the impacts of restructuring productive in the context of globalization, analyzing how the socio-economic factors influencing the dynamic of the population, whose configuration was shown to be contradictory according to social class busy. Accordingly, we studied the demographic configuration of the Metropolitan Region of Natal, analyzing their spatial distribution and their socio-demographic differences in light of building a type socio-space, which cuts the metropolitan space in homogeneous areas

Pobreza e desigualdades socioterritorias: uma problematização acerca da perspectiva territorial nas politicas públicas sociais no município de Pau dos Ferros/RN

El presente trabajo se constituye en un estudio sobre la pobreza y las desigualdades socio territoriales en el Brasil, problematizando la perspectiva territorial de las políticas públicas sociales observando la distribución espacial del Índice de Desarrollo de las familias (IDF) en el municipio de Pau dos Ferros/RN, así como las principales políticas sociales, a ejemplo del Programa Bolsa Familia. En este sentido, el objetivo principal de esa disertación se dió en la tentativa de comprender la importancia de la lectura previa del territorio para la reflexión sobre la pobreza en su aspecto multidimensional y para la territorialización de las políticas Públicas sociales construidas en el intento de minimizar la problemática de la desigualdad social, observando la distribución espacial do IDF en el municipio de Pau dos Ferros/RN. A partir del objetivo general trazado, hicimos una revisión teórica sobre los temas, pobreza, desigualdades sociales y políticas públicas, en el primero caso atentando para el aspecto multidimensional de esta, abogando la importancia de analizarnos la pobreza no apenas por el nivel de rienda, pero considerando otras dimensiones que corroboran para la constitución del ser pobre, como habitaciones precarias, falta de saneamiento básico e infraestructura, el no acceso a la salud, la educación y los otros servicios que posibilitan el individuo vivir con el mejor dignidad. Comprendiendo la importancia del conocimiento previo del territorio para que ocurra las debidas reflexiones e intervenciones en la realidad territorial buscamos reflexionar acerca de ese concepto en sus nexos con la construcción e implementación de las políticas públicas sociales teniendo la Política Nacional de Asistencia Social (PNAS) como política esencial y también el el Programa Bolsa Familia (PBF), una vez que buscamos compreender su importancia a partir de la visión del sujeto, o sea las beneficiadas del PBF en el Municipio de Pau dos Ferros. Para tanto, hicimos entrevistas orales con las beneficiadas del PBF que fueron elegidas aislada a partir de los equipos del CRAS, además de la aplicación de cuestionarios semiesctructurados y abiertos con gestores y asistentes sociales del muninicipio.Buscamos además trabajar con algunos datos del CadÚnico para el município en estudio proponiendo analisar las condiciones sociales y económicas de las famílias cadastradas. Algunos resultados fueron posibles, a saber, es necesario interpretarse la pobreza a partir de varias dimensiones para no tener el riesgo de quedarnos solamente en la perspectiva financiera, o sea de la rienda, que mismo sirva para lo emergencial no es suficiente para transformar las condiciones de vida de las famílias; PNAS puede ser considerada como un avanzo de la política social en el Brasil una vez que posuye importancia fundamental en la familia. Sin embargo, es preciso avanzar en la interpretación del territorio que en la política y en el habla de los agentes sociales , es interpretación apenas como un recorte donde deberán ocurrir las acciones para minimizar la pobreza ; al fin, o PBF es un programa de urgencia moral una vez que combate lo mas emergencial que es el directo de sobrevivir , pero aun no conseguió transformar de una manera significativa la pobreza en el país