Quintessence and Scalar Dark Matter in the Universe

Continuing with previous works, we present a cosmological model in which dark matter and dark energy are modeled by scalar fields $\Phi$ and $\Psi$, respectively, endowed with the scalar potentials $V(\Phi)=V_{o}[ \cosh {(\lambda \sqrt{\kappa_{o}}\Phi)}-1]$ and $\tilde{V}(\Psi)=\tilde{V_{o}}[ \sinh {(\alpha \sqrt{\kappa_{o}}\Psi)}] ^{\beta}$. This model contains 95% of scalar field. We obtain that the scalar dark matter mass is $m_{\Phi}\sim 10^{-26}eV.$ The solution obtained allows us to recover the success of the standard CDM. The implications on the formation of structure are reviewed. We obtain that the minimal cutoff radio for this model is $r_{c}\sim 1.2 kpc.$Comment: 4 pages REVTeX, 3 eps color figures. Minor changes and references updated. To appear in Classical and Quantum Gravity as a Letter to the Editor. More information at http://www.fis.cinvestav.mx/~siddh/PHI

Diversidade florística em quintais agroflorestais de quatro localidades, Parintins - Amazonas.

O objetivo deste trabalho foi verificar a diversidade das espécies em pomares caseiros no assentamento de Vila Amazônia

Mancha negra do abacaxi no Pará.

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Scalar Field as Dark Matter in the Universe

We investigate the hypothesis that the scalar field is the dark matter and the dark energy in the Cosmos, wich comprises about 95% of the matter of the Universe. We show that this hypothesis explains quite well the recent observations on type Ia supernovae.Comment: 4 pages REVTeX, 1 eps figure. Minor changes. To appear in Classical and Quantum Gravit

Hydrodynamics of galactic dark matter

We consider simple hydrodynamical models of galactic dark matter in which the galactic halo is a self-gravitating and self-interacting gas that dominates the dynamics of the galaxy. Modeling this halo as a sphericaly symmetric and static perfect fluid satisfying the field equations of General Relativity, visible barionic matter can be treated as ``test particles'' in the geometry of this field. We show that the assumption of an empirical ``universal rotation curve'' that fits a wide variety of galaxies is compatible, under suitable approximations, with state variables characteristic of a non-relativistic Maxwell-Boltzmann gas that becomes an isothermal sphere in the Newtonian limit. Consistency criteria lead to a minimal bound for particle masses in the range $30 \hbox{eV} \leq m \leq 60 \hbox{eV}$ and to a constraint between the central temperature and the particles mass. The allowed mass range includes popular supersymmetric particle candidates, such as the neutralino, axino and gravitino, as well as lighter particles ($m\approx$ keV) proposed by numerical N-body simulations associated with self-interactive CDM and WDM structure formation theories.Comment: LaTeX article style, 16 pages including three figures. Final version to appear in Classical and Quantum Gravit

Production of activated carbon from fast-pyrolysis biochar.

Thermochemical conversion of lignocellulosic biomass via fast-pyrolysis technique has become an interesting alternative to produce valuable bio-based products, such as the bio-oil. This alternative, for instance, can increase even more the profitability of such well-consolidated pulp and paper industries by turning it into more energetically self-sufficient processo Besides bio-oil, the fast-pyrolysis process results in many byproducts with high economic and environmental benefits. Biochar is one of these byproducts, and it can be activated by physical and chemical methods to use for water treatment and for environmental remediation. This study investigates the activation of biochar obtained from the fast-pyrolysis of wood biomass. The biochar was collected from a pilot-plant of bio-oil production and then activated via physical route (C02) at 800°C for 30 and 60 minutes; and via chemical route (H3P04) at 450, 550 and 650°C for 60 minutes. The activated carbon was characterized by product yield, proximate analysis, surface area and thermogravimetric analysis. The chemical routes with H3P04 were more efficient than the physical routes with CO2. The chemical activation at 450°C presented the highest product yield (80.47%) followed by a decrease in the yield to 71-75% with the increase of the temperature. The fixed carbon content increased after both physical and chemical activation, remaining around 91%. On the other hand, the volatile matter decreased significantly, especially in the physical routes. The surface area increased from 17.94 (untreated biochar) to 450-655 m2/g, confirming the improvement of the porosity, mainly in the biochar activated by H3P04 at 450°C and by CO2 for 60 minutes. Ali biochar activated by chemical routes presented similar residual mass at 600°C, whereas the material physically activated with CO2 presented lower residual mass, especially the one treated for 30 minutes. Overall, these results provide an alternative to produce a high added-value material from a fast-pyrolysis byproduct, encouraging the exploration of thermochemical conversion of lignocellulosic biomass

Anatomopathological changes associated with biofilm production by Corynebacterium Pseudotuberculosis isolates in goats.

Caseous lymphadenitis has Corynebacterium pseudotuberculosis as etiological agent, and is an infectious disease, which affects mainly goats and sheep and causes great economic losses

Atividades das enzimas catalase e esterase em sementes de café produzidas sob diferentes tratamentos de fertirrigação.

Com a escassez das áreas produtivas e com a limitação de algumas regiões pela deficiência hídrica, a irrigação vem sendo cada vez mais utilizada, seja para aumentar a produtividade a qualidade dos produtos ou para diminuir os custos da aplicação de adubo. Na cultura de café está sendo utilizada, principalmente, a fertirrigação, que além das vantagens destacadas evita a compactação do solo, concorre para um menor gasto de energia e evita os danos mecânicos causadas por máquinas usadas na adubação. Sabe-se que, dentre outros fatores, a adubação pode influenciar na qualidade de sementes, além de interferir nos resultados dos padrões de proteínas e de isoenzimas, como a catalase e a esterase Assim, este trabalho foi realizado com o objetivo de avaliar os efeitos da fertirrigação nos padrões isoenzimáticos da catalase e esterase em sementes de café produzidas em lavoura cafeeira irrigada e adubada com diferentes doses de nutrientes nitrogenados. Os frutos foram colhidos em lavoura da Universidade Federal de Lavras, espécie Coffea arábica L., sendo fertirrigado por um sistema de gotejamento e dois parcelamentos, doze e quatro aplicações por ano. Após a colheita dos frutos no estádio cereja, estes foram despolpados , desmucilados , secados e submetidos às análises de eletroforese de isoenzimas. Da análise dos resultados, constatou-se que os tratamentos de fertirrigação com diferentes arcelamentos e doses de adubação não afetam o perfil eletroforético das isoenzimas catalase e esterase