462 research outputs found
Loop correction to the scalar Casimir energy density and generation of topological mass due to a helix boundary condition in a scenario with Lorentz violation
In this paper the effective potential approach in quantum field theory is
used in order to investigate self-interaction loop correction to the Casimir
energy density and generation of topological mass for both massless and massive
real scalar fields. It is assumed that the scalar field obeys a helix boundary
condition. In addition, it is also considered a CPT-even aether-type violation
of the Lorentz symmetry. In the absence of the Lorentz violation we obtain
analytical expressions for the loop correction to the Casimir energy density
and to the mass of the scalar field. The same expressions are also obtained
assuming the Lorentz violation in each of the spacetime directions. We also
show some graphs that exhibit how the loop correction and the Lorentz violation
affect the the Casimir energy density and the mass of the scalar field.Comment: 17 pages, 7 figure
Efeito do corte de emparelhamento sobre a qualidade dos componentes da fibra e do teor de lignina do azevém (Lolium multiflorum, LAM.) no estágio vegetativo.
Phylogeny, molecular dating and zoogeographic history of the titi monkeys (Callicebus, Pitheciidae) of eastern Brazil
The titi monkeys belong to a genus of New World primates endemic to South America, which were recently reclassified in three genera (Cheracebus, Plecturocebus and Callicebus). The genus Callicebus, which currently includes five species, is endemic to eastern Brazil, occurring in the Caatinga, Savanna, and Atlantic Forest biomes. In the present study, we investigated the validity of these species and inferred their phylogenetic relationships, divergence times, and biogeographic patterns based on the molecular analysis of a concatenated sequence of 11 mitochondrial and nuclear DNA markers, derived from 13 specimens. We ran Maximum Likelihood (ML) and Bayesian Inference (BI) analyses, and estimated genetic distances, divergence times. Ancestral areas were estimated on BioGeoBears. Our results suggest that at about twelve million years ago, the ancestor of all titi monkeys inhabited a wide area that extended from the Amazon forest to the South of the Atlantic forest. A first vicariant event originated Cheracebus in the West of the Amazon and the ancestor of Callicebus and Plectorocebus which, later were separated by a second one. The diversification of Callicebus occurred during the Plio-Pleistocene (beginning at 5 Ma) probably influenced by climatic fluctuations and geological events. Therefore, the results of the present work confirmed the existence of five species that currently inhabit forested areas under increasing threat from human activities. Thus, a reliable diagnosis of the taxonomic status of species living in endangered environments is extremely important for the development of conservation measures
Utilização do taxi-branco (Sclerolobium paniculatum Vogel) para recuperação de solos degradados pela agricultura migratória.
O objetivo deste trabalho foi de avaliar a dinâmica da materia organica e de nutrientes em duas áreas abandonadas: uma plantada com taxi branco e outra com capoeira sem enriquecimento
Efeito de diferentes tempos de emurchecimento nos teores de fibra, lignina e proteína bruta da silagem de azevém (Lolium multiflorum, LAM.) no estágio vegetativo.
Zoneamento de riscos climáticos para a cultura do amendoim no Estado do Ceará.
bitstream/CNPAT-2010/11916/1/Bd-30.pd
Resistência mecânica à penetração de um argissolo amarelo de tabuleiros costeiros e desenvolvimento radicular de variedades de cana-de-açúcar.
- …