Dark Energy
Mostrando 13-24 de 220 artigos, teses e dissertações.
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13. Tópicos em cosmologia com campos escalares
Modelos cosmológicos envolvendo campos escalares permitem a descrição de uma fase de expansão cósmica acelerada e, portanto, se apresentam como uma alternativa promissora no estudo da inflação cósmica e da energia escura. Estamos aqui interessados em analisar esses modelos cosmológicos; em especial, vamos explorar soluções cosmológicas baseadas n
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 20/05/2011
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14. Pigmentos de pinturas rupestres pré-históricas do sítio Letreiro do Quinto, Pedro II, Piauí, Brasil
The Letreiro do Quinto rock shelter is located in the rural area of the city of Pedro II, Piauí, Brazil. The sandstone walls of the shelter are covered with prehistoric rupestrian paintings, painted in patterns of yellow and light and dark red hues. The chemical-mineralogical characterization of the prehistoric pigments was made with energy dispersive spect
Química Nova. Publicado em: 2011
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15. Análise de metodologias para correção atmosférica e estimativa do albedo da superfície usando imagens Landsat 5, TM.
Este trabalho objetivou analisar a aplicação de diferentes metodologias para correção atmosférica e estimativa do albedo da superfície com imagens Landsat 5 ? TM para a região que abrange parte do megaleque aluvial do rio Taquari (Pantanal). Foram avaliados os métodos de correção atmosférica DOS (dark object subtraction), método de correção bas
SIMPÓSIO DE GEOTECNOLOGIAS NO PANTANAL. Publicado em: 2011
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16. Observational consequences of a dark interaction model
We study a model with decay of dark energy and creation of the dark matter particles. We integrate the field equations and find the transition redshift where the evolution process of the universe change the accelerated expansion, and discuss the luminosity distance, acoustic oscillations and the statefinder parameters.
Brazilian Journal of Physics. Publicado em: 2010-12
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17. Brazing of metals to zirconia mechanically metallized with titanium
The mechanical metallization is a successful technique at laboratory scale and specially applied to oxide ceramics. Indirect brazing process of zirconia to metals is achieved using active-metal-free filler alloys on previously metallized ceramic. Stabilized zirconia ceramics were mechanically metallized with Ti and wetting conditions evaluated using commerci
Journal of the Brazilian Society of Mechanical Sciences and Engineering. Publicado em: 2010-12
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18. Domain wall, stiff matter and ultra-relativistic particles from a generalized double-component dark energy model
This letter discusses a modified Friedmann-Robertson-Walker cosmology in which the equation of state behaves like p = 3ηa m ρn -ρ,(η,m,n) ∈ . Many interesting features are revealed in particular the manifestation of domain wall, cosmic string, stiff matter, dust and radiation/ultra-relat
Brazilian Journal of Physics. Publicado em: 2010-06
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19. Dual-curing, self-adhesive resin cement: influence of the polymerization modes on the degree of conversion and microhardness
RelyX TM Unicem, dual-curing self-adhesive resin cement, was tested in order to evaluate the degree of conversion (DC) and Vickers microhardness (VMH). The specimens were prepared into 4 groups (GR). For GR1, the specimens were irradiated with 500 mW.cm-2 during 20 seconds while for GR3 the same intensity was used but the irradiation time was 40 seconds. The
Materials Research. Publicado em: 2010-06
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20. Dark Energy and The Accelerating Universe: Conceptual Aspects and Observational Tests / Energia escura e aceleração do Universo: Aspectos conceituais e testes observacionais
In the last decade, the extraordinary progress of the astronomical observations (distances with supernovas, matter and cosmic background radiation (CBR) power spectrum, X-ray surface brightness of galaxy clusters, etc) associated with important theoretical developments turned Cosmology one of the most exciting frontiers of contemporary science. In this thesi
Publicado em: 2010
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21. O vértice D*Dp usando as regras de soma da QCD / The D*Dp vertex using the QCD sum rules
The particle physics have been studying topics like the Quark-Gluon Plasma (QGP), Higgs boson and dark matter, which require experiments in heavy-ion collisions. Therefore, accelerators capable of generate high energy particle beams are necessary and may generate new physics. When new data arise in the laboratories, new processes are necessary to explain thi
Publicado em: 2010
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22. Dark energy and cyclic universe from Arnowitt-Deser-Misner renormalizable group approach
We discuss the generic features of the accelerated universe from Arnowitt-Deser-Misner renormalizable group approach applied for gravity models with variable gravitational coupling constant and cosmological constant. The universe undergoes an endless sequence of cosmic eras which starts inflating after a Big Bang and end contracting to a Big Crunch dominated
Brazilian Journal of Physics. Publicado em: 2009-03
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23. Observational Constraints in Interacting Dark Energy Models / Vínculos observacionais em modelos de energia escura interagente
In the present work the possibility of a dark energy interacting with dark matter has been investigated. We considered a flat Friedmann-Robertson-Walker space-time with two alternative interacting dark energy models. In the first, the interaction term, appearing in the energy conservation equations was introduced by purely phenomenological reasons. In the se
Publicado em: 2009
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24. Conversão de materia escura não-relativistica em relativistica / Conversion of non relativistic dark matter into relativistic matter
The structure formation through the history of the universe crucially depends on the competition between non-relativistic and relativistic matter effects. We know that there are mechanisms which convert the contents of one into the other. Particularly the explosion of a core-collapse supernova converts an energy corresponding to 99% of the gravitational bind
Publicado em: 2009