79 research outputs found
Dressed States Approach to Quantum Systems
Using the non-perturbative method of {\it dressed} states previously
introduced in JPhysA, we study effects of the environment on a quantum
mechanical system, in the case the environment is modeled by an ensemble of non
interacting harmonic oscillators. This method allows to separate the whole
system into the {\it dressed} mechanical system and the {\it dressed}
environment, in terms of which an exact, non-perturbative approach is possible.
When applied to the Brownian motion, we give explicit non-perturbative formulas
for the classical path of the particle in the weak and strong coupling regimes.
When applied to study atomic behaviours in cavities, the method accounts very
precisely for experimentally observed inhibition of atomic decay in small
cavities PhysLA, physics0111042
Fotopedologia, espectroscopia e sistema de informação geográfica na caracterização de solos desenvolvidos do Grupo Barreiras no Amapá
Metazoan parasite of lambari Astyanax altiparanae, collected from the Peixe river, São Paulo, southeast of Brazil
Peroxide-based route for the synthesis of zinc titanate powder
In this work the thermodynamical solubility diagrams of zinc and titanium hydroxides
were reviewed in order to determine the conditions for maximum degree of phase composition
homogenization of precipitates. Experimental investigation of dependency of titanium peroxohydroxide
solubility on solution acidity has been carried out and coprecipitation of zinc ions has been
studied. It was concluded that precipitation by constant addition of mixed salts and base solutions
into the mother liquor with constant acidity of pH 8.5 allows maximizing homogenization of
precipitate composition. Thermal treatment process of mixed zinc and titanium hydroxides
coprecipitated with hydrogen peroxide was studied using thermogravimetric analysis, differential
thermal analysis and X-ray diffraction methods. It was found that precipitates of co-precipitated
mixtures of zinc and titanium hydroxides contained impurities of salts precursors of the Zn
(NO3)2 and TiOCl2 at a level of 1%. The experimental data demonstrate the influence of hydrogen
peroxide on crystal growth rate of the zinc titanate during thermal treatment. The temperature
ranges and kinetic parameters of hydroxide mixture dehydration, decomposition of the titanium
peroxohydroxide and precursor impurities were determined
Distribution of frogs in riparian areas of an urban forest fragment in Central Amazonia
Range extensions along western Atlantic for Epialtidae crabs (Brachyura, Majoidea) genera Acanthonyx Latreille, 1828 and Epialtus H. Milne Edwards, 1834
The present study provided information extending the known geographical distribution of three species of majoid crabs, the epialtids Acanthonyx dissimulatus Coelho, 1993, Epialtus bituberculatus H. Milne Edwards, 1834, and E. brasiliensis Dana, 1852. Specimens of both genera from different carcinological collections were studied by comparing morphological characters. We provide new data that extends the geographical distributions of E. bituberculatus to the coast of the states of Paraná and Santa Catarina (Brazil), and offer new records from Belize and Costa Rica. Epialtus brasiliensis is recorded for the first time in the state of Rio Grande do Sul (Brazil), and A. dissimulatus is reported from Quintana Roo, Mexico. The distribution of A. dissimulatus, previously known as endemic to Brazil, has a gap between the states of Espírito Santo and Rio de Janeiro. However, this restricted southern distribution is herein amplified by the Mexican specimens
Soil macrofauna density and diversity across a chronosequence of tropical forest restoration in Southeastern Brazil
Quantificação de matéria orgânica do solo através de modelos matemáticos utilizando colorimetria no sistema Munsell de cores
Alteração de propriedades físicas e atividade microbiana de um latossolo amarelo álico após o cultivo com fruteiras perenes e mandioca
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