Host status of different crops for Meloidogyne ethiopica control.

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Observational constraints on late-time Lambda(t) cosmology

The cosmological constant, i.e., the energy density stored in the true vacuum state of all existing fields in the Universe, is the simplest and the most natural possibility to describe the current cosmic acceleration. However, despite its observational successes, such a possibility exacerbates the well known cosmological constant problem, requiring a natural explanation for its small, but nonzero, value. In this paper we study cosmological consequences of a scenario driven by a varying cosmological term, in which the vacuum energy density decays linearly with the Hubble parameter. We test the viability of this scenario and study a possible way to distinguish it from the current standard cosmological model by using recent observations of type Ia supernova (Supernova Legacy Survey Collaboration), measurements of the baryonic acoustic oscillation from the Sloan Digital Sky Survey and the position of the first peak of the cosmic microwave background angular spectrum from the three-year Wilkinson Microwave Anisotropy Probe.Comment: Some important revisions. To appear in Physical Review

Risk factors for infection by Toxoplasma gondii in herds of goats in Ceará, Brazil.

Com o objetivo de se identificarem os fatores de risco associados à presença de infecção por toxoplasmose em rebanhos caprinos no estado do Ceará, Brasil, soros sanguíneos de 2362 caprinos foram testados por meio de ELISA. A prevalência estimada pelo ELISA foi 25,1%. Os fatores de risco identificados nas propriedades foram: idade dos animais, número de gatos, comedouro manufaturado de madeira e ausência de comedouro. Em caprinos com mais de 37 meses de idade o risco de estarem infectados pelo T. gondii foi 2,01 vezes maior (IC 95%; 1,55 - 2,61) que em animais mais jovens. Maior risco de infecção foi observado em fazendas com mais de 10 gatos (OR = 1,73; IC 95% 1,01 - 3,33). Quando a propriedade utilizava comedouros de madeira, o risco de estarem infectados foi também maior (OR = 7.81; IC 95%; 1.66 - 36.67). Animais oriundos de propriedades sem comedouro também apresentaram alto risco de infecção (OR = 5.50; IC 95%; 1,24 - 24,39)

Monte-Carlo calculation of longitudinal and transverse resistivities in a model Type-II superconductor

We study the effect of a transport current on the vortex-line lattice in isotropic type-II superconductors in the presence of strong thermal fluctuations by means of 'driven-diffusion' Monte Carlo simulations of a discretized London theory with finite magnetic penetration depth. We calculate the current-voltage (I-V) characteristics for various temperatures, for transverse as well as longitudinal currents I. From these characteristics, we estimate the linear resistivities R_xx=R_yy and R_zz and compare these with equilibrium results for the vortex-lattice structure factor and the helicity moduli. From this comparison a consistent picture arises, in which the melting of the flux-line lattice occurs in two stages for the system size considered. In the first stage of the melting, at a temperature T_m, the structure factor drops to zero and R_xx becomes finite. For a higher temperature T_z, the second stage takes place, in which the longitudinal superconducting coherence is lost, and R_zz becomes finite as well. We compare our results with related recent numerical work and experiments on cuprate superconductors.Comment: 4 pages, with eps figure

Caracterização de serrapilheira em agroecossistemas na Amazônia Central.

Este estudo teve como objetivo comparar o estoque de serrapilheira em ecossistemas naturais (floresta primária) e agroecossistemas (monocultivos e policultivos), bem como avaliar algumas características químicas dessas serrapilheiras e do solo, nas condições tropicais amazônicas