920 resultados para Open clusters and associations: Cygnus OB1, Cygnus OB9


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This paper presents an Advanced Traveler Information System (ATIS) developed on Android platform, which is open source and free. The developed application has as its main objective the free use of a Vehicle-to- Infrastructure (V2I) communication through the wireless network access points available in urban centers. In addition to providing the necessary information for an Intelligent Transportation System (ITS) to a central server, the application also receives the traffic data close to the vehicle. Once obtained this traffic information, the application displays them to the driver in a clear and efficient way, allowing the user to make decisions about his route in real time. The application was tested in a real environment and the results are presented in the article. In conclusion we present the benefits of this application. © 2012 IEEE.

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Background: Functional redundancy has been debated largely in ecology and conservation, yet we lack detailed empirical studies on the roles of functionally similar species in ecosystem function. Large bodied frugivores may disperse similar plant species and have strong impact on plant recruitment in tropical forests. The two largest frugivores in the neotropics, tapirs (Tapirus terrestris) and muriquis (Brachyteles arachnoides) are potential candidates for functional redundancy on seed dispersal effectiveness. Here we provide a comparison of the quantitative, qualitative and spatial effects on seed dispersal by these megafrugivores in a continuous Brazilian Atlantic forest. Methodology/Principal Findings: We found a low overlap of plant species dispersed by both muriquis and tapirs. A group of 35 muriquis occupied an area of 850 ha and dispersed 5 times more plant species, and 13 times more seeds than 22 tapirs living in the same area. Muriquis dispersed 2.4 times more seeds in any random position than tapirs. This can be explained mainly because seed deposition by muriquis leaves less empty space than tapirs. However, tapirs are able to disperse larger seeds than muriquis and move them into sites not reached by primates, such as large forest gaps, open areas and fragments nearby. Based on published information we found 302 plant species that are dispersed by at least one of these megafrugivores in the Brazilian Atlantic forest. Conclusions/Significance: Our study showed that both megafrugivores play complementary rather than redundant roles as seed dispersers. Although tapirs disperse fewer seeds and species than muriquis, they disperse larger-seeded species and in places not used by primates. The selective extinction of these megafrugivores will change the spatial seed rain they generate and may have negative effects on the recruitment of several plant species, particularly those with large seeds that have muriquis and tapirs as the last living seed dispersers. © 2013 Bueno et al.

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In this paper, a combined theoretical and experimental study on the electronic structure and photoluminescence (PL) properties of beta zinc molybdate (β-ZnMoO4) microcrystals synthesized by the hydrothermal method has been employed. These crystals were structurally characterized by X-ray diffraction (XRD), Rietveld refinement, Fourier transform Raman (FT-Raman) and Fourier transform infrared (FT-IR) spectroscopies. Their optical properties were investigated by ultraviolet-visible (UV-Vis) absorption spectroscopy and PL measurements. First-principles quantum mechanical calculations based on the density functional theory at the B3LYP level have been carried out. XRD patterns, Rietveld refinement, FT-Raman and FT-IR spectra showed that these crystals have a wolframite-type monoclinic structure. The Raman and IR frequencies experimental results are in reasonable agreement with theoretically calculated results. UV-Vis absorption measurements shows an optical band gap value of 3.17 eV, while the calculated band structure has a value of 3.22 eV. The density of states indicate that the main orbitals involved in the electronic structure of β-ZnMoO4 crystals are (O 2p-valence band and Mo 4d-conduction band). Finally, PL properties of β-ZnMoO4 crystals are explained by means of distortions effects in octahedral [ZnO6] and [MoO6] clusters and inhomogeneous electronic distribution into the lattice with the electron density map. © 2013 Elsevier Ltd. All rights reserved.

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Ba(Zr0.75Ti0.25)O3 (BZT-75/25) powders were synthesized by the polymeric precursor method. Samples were structurally characterized by X-ray diffraction (XRD), Rietveld refinement, X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) techniques. Their electronic structures were evaluated by first-principle quantum mechanical calculations based on density functional theory at the B3LYP level. Their optical properties were investigated by ultraviolet-visible (UV-Vis) spectroscopy and photoluminescence (PL) measurements at room temperature. XRD patterns and Rietveld refinement data indicate that the samples have a cubic structure. XANES spectra confirm the presence of pyramidal [TiO5] clusters and octahedral [TiO6] clusters in the disordered BZT-75/25 powders. EXAFS spectra indicate distortion of Ti-O and Ti-O-Ti bonds the first and second coordination shells, respectively. UV-Vis absorption spectra confirm the presence of different optical bandgap values and the band structure indicates an indirect bandgap for this material. The density of states demonstrates that intermediate energy levels occur between the valence band (VB) and the conduction band (CB). These electronic levels are due to the predominance of 4d orbitals of Zr atoms in relation to 3d orbitals of Ti atoms in the CB, while the VB is dominated by 2p orbitals related to O atoms. There was good correlation between the experimental and theoretical optical bandgap values. When excited at 482 nm at room temperature, BZT-75/25 powder treated at 500 C for 2 h exhibited broad and intense PL emission with a maximum at 578 nm in the yellow region. © 2013 Elsevier Ltd. All rights reserved.

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CCTO thin films were deposited on Pt(1 1 1)/Ti/SiO2/Si substrates using a chemical (polymeric precursor) and pressure method. Pressure effects on CCTO thin films were evaluated by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and optical properties which revealed that a pressure film (PF) is denser and more homogeneous than a chemical film (CF). Pressure also causes a decrease in the band gap and an increase in the photoluminescence (PL) emission of CCTO films which suggests that the pressure facilitates the displacement of Ti in the titanate clusters and the charge transference from TiO6 to [TiO5V0z], [TiO5V0z] to [CaO11V0z] and [TiO5V0z] to [CuO4]x. © 2013 Elsevier B.V. All rights reserved.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Despite having relatively open economies and a dedicated strategic focus on export expansion, Caribbean economies still account for a small proportion of global trade (goods and services). This paper therefore posits that the subregion adopt a new dais of regional integration, which favours deeper trade and economic integration with countries which are the region’s natural trading partners.

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Over the past two years the global economy has experienced substantial economic turmoil, resulting in severe economic contraction. While there has been a recent return to growth, this situation has impacted all economic sectors worldwide. In the highly tourism-dependent region of the Caribbean, the impact of the global economic crisis has been most notable on the tourism sector, which, from the early 1990s, became the key driver of economic growth for the region. The eventual emergence of this sector reflects an economic development history which was previously underpinned by the export of agricultural commodities, and subsequently by the adoption of the import substitution industrialization model as promulgated by Arthur Lewis. This was further stimulated by spectacular economic contraction in Caribbean economies during the 1980s as a result of changes in the global terms of trade for commodities, generally low levels of competitiveness for manufactured goods, as well as weak institutional and governance frameworks. Ultimately, many economies began to reflect fiscal and balance of payments constraints. By the end of the 1990s, too, evidence of declining competitiveness even in the tourism sector began to become apparent particularly when evaluated under the framework of the Butler Tourism Area Life- Cycle (TALC) model. The recent economic crisis, therefore, provides an opportunity to reflect on the overall approach to economic development in the Caribbean, and to assess the implications of the region’s response to the crisis. This analysis makes the case for the future development of the sector to be based on two broad strategies. The first is to deepen the integration of the tourism sector into the broader economy through the diversification of the regional tourism product, as well as the enhancement of linkages with other sectors, while the second is to expand the tourism sector into a total service economy through the introduction of new services. Considering linkages, the development of clusters and value chains to support the tourism sector is identified with respect to agriculture and food, handicraft, and furnishings. Among the new services identified are education, wellness, yachting and boating, financial services, and information and communications technologies (ICT). This overall strategy is deemed to be better suited to the macroeconomic realities of the Caribbean, where high labour costs and other structural rigidities require a high-valued specialty tourism product in order to sustain the sector’s global competitiveness.