Potencial de utilização de extrato padronizado de Ruta graveolens como agente inibidor de Magnaporthe oryzae.

O objetivo foi avaliar o potencial do extrato vegetal líquido padronizado de Ruta graveolens no controle da brusone

Raças fisiológicas e linhagens de uma população contemporânea de Magnaporthe oryzae associada à brusone do arroz irrigado no Sul do Brasil.

Objetivou-se identificar raças fisiológicas, com base em séries diferenciadoras, e linhagens, com base em marcadores microssatélites, em uma população de Magnaporthe oryzae do sul do Brasil

Exchange and correlation near the nucleus in density functional theory

The near nucleus behavior of the exchange-correlation potential $v_{xc}({\bf r})$ in Hohenberg-Kohn-Sham density functional theory is investigated. It is shown that near the nucleus the linear term of $O(r)$ of the spherically averaged exchange-correlation potential ${\bar v}_{xc}(r)$ is nonzero, and that it arises purely from the difference between the kinetic energy density at the nucleus of the interacting system and the noninteracting Kohn-Sham system. An analytical expression for the linear term is derived. Similar results for the exchange $v_{x}({\bf r})$ and correlation $v_{c}({\bf r})$ potentials are also obtained separately. It is further pointed out that the linear term in $v_{xc}({\bf r})$ arising mainly from $v_{c}({\bf r})$ is rather small, and $v_{xc}({\bf r})$ therefore has a nearly quadratic structure near the nucleus. Implications of the results for the construction of the Kohn-Sham system are discussed with examples.Comment: 10 page

Correlated sampling in quantum Monte Carlo: a route to forces

In order to find the equilibrium geometries of molecules and solids and to perform ab initio molecular dynamics, it is necessary to calculate the forces on the nuclei. We present a correlated sampling method to efficiently calculate numerical forces and potential energy surfaces in diffusion Monte Carlo. It employs a novel coordinate transformation, earlier used in variational Monte Carlo, to greatly reduce the statistical error. Results are presented for first-row diatomic molecules.Comment: 5 pages, 2 postscript figure

New robust observables on Rayleigh waves affected by an underground cavity: from numerical to experimental modelling

International audienceThe investigation and monitoring of shallow hazards due to the presence of underground cavities remain a challenge for geophysical approaches. Thus, seismic surface waves have been tested in several recent research projects in order to detect and localize voids as well as to determine their geometries. Among these works, numerous numerical studies have proved the feasibility of Rayleigh waves to detect cavities. However, most imagery processes adapted to R waves are faced with difficulties when applying them to real data. This limitation points to a major problem: the interactions between Rayleigh waves and a cavity are complex, particularly in the case of dispersing and attenuating surrounding media. Here, a combined approach based on numerical and experimental data obtained in a reduced-scale measurement bench is conducted to better understand the seismic wave propagation phenomena involved in the presence of a cavity and define robust observables that can be used in field measurements. The observables bearing the cavity signature are studied qualitatively and quantitatively on numerical and experimental recordings. The latter take into account all the propagation phenomena involved. The observations are carried out on the vertical and horizontal component of the Rayleigh wave displacement. The selected observables are studied depending on non-dimensional cavity's parameters versus the frequency, that is the wavelength-to-size ratio and the wavelength-to-depth ratio. The effects of the cavity's parameters on the observables show particularities as a function of these components, such as a higher rate of the amplitude on the horizontal component as well as a perturbation of the direct seismic surface wave amplitude above the cavity, also higher on the horizontal component. This latter feature is particularly visible on the variation of the elliptical particle motion recorded at the surface. It can be linked to the mode conversions that occur in the vicinity of the cavity and which predominate on the horizontal component when the signal is normalized

Indução de resistência e promoção de crescimento em plantas de arroz tratadas com silício e bioagentes.

Os bioagentes são conhecidos pela eficácia em induzir a defesa e promover crescimento das plantas, e o silício por suprimir doenças ao reforçar as barreiras físicas. O efeito supressor e promotor da combinação entre adubação silicatada e bioindutores foi investigado no patossitema arroz/Magnaporthe oryzae, avaliando-se as concentrações 0, 1, 2, 4 e 8 ton.ha-1 de silicato de cálcio e magnésio e o modo de aplicação dos bioagentes Rizo-46, Rizo-55 e Trichoderma sp

Avaliação da variabilidade patogênica de Magnaporthe oryzae em duas séries diferenciadoras.

O objetivo deste trabalho foi quantificar a diversidade e a complexidade dos patótipos de M. oryzae oriundos de sistemas de cultivos de várzeas (irrigado) e de terras altas (sequeiro), utilizando-se a série diferenciadora internacional e a série de linhagens isogênicas

Antagonismo in vitro e in vivo entre Sporobolomyces sp. e patógenos do arroz.

O objetivo do trabalho foi identificar os melhores antagonistas in vitro e in vivo para M. oryzae dentre nove isolados de Sporobolomyces sp. previamente selecionados do filoplano do arroz

Redução da severidade da brusone foliar em arroz por Sarocladium oryzae.

O objetivo do trabalho foi avaliar, em casa de vegetação, o potencial de Sarocladium oryzae na redução da severidade da brusone nas folhas de arroz. O isolado de S. oryzae, Sa03, da coleção de fungos e microrganismos multifuncionais da Embrapa Arroz e Feijão (CFMMCNPAF) foi cultivado em meio de cultura líquido (Omura, 1976) para a obtenção do filtrado e em BDA para obtenção de esporos