Effect of Plant Sterols and Tannins on Phytophthora ramorum Growth and Sporulation

Elicitin-mediated acquisition of plant sterols is required for growth and sporulation of Phytophthora spp. This study examined the interactions between elicitins, sterols, and tannins. Ground leaf tissue, sterols, and tannin-enriched extracts were obtained from three different plant species (California bay laurel, California black oak, and Oregon white oak) in order to evaluate the effect of differing sterol/tannin contents on Phytophthora ramorum growth. For all three species, high levels of foliage inhibited P. ramorum growth and sporulation, with a steeper concentration dependence for the two oak samples. Phytophthora ramorum growth and sporulation were inhibited by either phytosterols or tannin-enriched extracts. High levels of sterols diminished elicitin gene expression in P. ramorum; whereas the tannin-enriched extract decreased the amount of ‘functional’ or ELISA-detectable elicitin, but not gene expression. Across all treatment combinations, P. ramorum growth and sporulation correlated strongly with the amount of ELISA-detectable elicitin (R ²?=?0.791 and 0.961, respectively).     

What goes up: Recent trends in Mexican residential energy use

Energy use in the Mexican residential sector is steadily increasing. Important factors contributing to the increase include changes in the types of housing built, heating, cooling, water-heating equipment and other appliances.     

Optimizing the search directions of a mixed DDM applied on cracks

Optimization and Engineering - Domain Decomposition Methods (DDM) are a set of numerical techniques that efficiently implement parallel computing for the structural analysis of large domains. This...     

An Independent Component Analysis Approach for Wide-Area Monitoring of Power System Disturbances

Abstract

Wide-area power system monitoring based on phasor measurement units allows collecting a set of physical variables for evaluating the system security and stability, as well as for detecting power system disturbances. However, trends, noise and non-Gaussian distribution in measurements are important challenges for carrying out the detection, localization and visualization of power system disturbances. In this paper, a methodology that combines independent component analysis with statistical indices for detecting and visualizing anomalous dynamic events from wide-area measurements is proposed. From the statistical indices, two charts are also proposed to provide a better understanding of the system disturbances. Finally, a set of simulated data obtained from a transient stability model of the New England/New York test system is used to demonstrate the effectiveness of the proposed technique.     

Symmetric and asymmetric dynamic characterization of mode‐III fracture in epoxy/unidirectional carbon‐fibre composites

This paper experimentally analyses the delamination behaviour of a composite material under mode III fracture as a function of the loading mode applied during the fatigue tests was carried out in two different ways. First, the test specimens were loaded cyclically in a single direction of delamination until reaching a certain fracture energy and subsequently returning to the starting point. Second, cyclic loading was applied both in one direction of delamination and in the opposite direction until reaching the same fracture energies, though in two opposite directions. The experimental results revealed clear differences in the fatigue behaviour of the material when the way of applying the load varied. In both cases, a statistical analysis of the results was carried out in order to evaluate the existing differences more suitably. Furthermore, a fractographic analysis was conducted for both types of loading in order to distinguish possible differences at the microstructural level.     

A new variational self-regular traction-BEM formulation for inter-element continuity of displacement derivatives

In this work, a non-symmetric variational approach is derived to enforce C ^1, continuity at inter-element nodes for the self-regular traction-BIE. This variational approach uses only Lagrangian C ⁰ elements. Two separate algorithms are derived. The first one enforces C ^1, continuity at smooth inter-element nodes, and the second enforces continuity of displacement derivatives in global coordinates at corner nodes, where C ^1, continuity cannot be enforced. The variational formulation for the traction-BIE is implemented in this work for two elastostatics problems with various discretizations and polynomial interpolants. Local and global measures of the discretization error are obtained by means of an error estimator recently derived by the authors. Comparisons are also made with the displacement-BIE, which does not require C ^1, continuity for the displacement. The lack of smoothness of the displacement derivatives at the inter-element nodes is shown to be an important source of both local and global error for the traction-BIE formulation, especially for quadratic elements. The accuracy of the boundary solution obtained from the traction-BIE improves significantly when C ^1, continuity is enforced where possible, i.e., at the smooth inter-element nodes only. The first author acknowledges the support received from CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico. The third author gratefully acknowledges support by the National Science Foundation (CTS-9983961). The fourth author acknowledges the support received from FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais.