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Present Methodology (present + methodology)
Selected AbstractsNew methods for the detection of insecticide resistant Myzus persicae in the U.K. suction trap networkAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 3 2008James A. Anstead Abstract 1,Myzus persicae is a highly polyphagous pest of U.K. agriculture. It presents particular control difficulties because it has developed resistance to several insecticide classes. 2,For almost 20 years, M. persicae collected in the U.K. suction trap network have been analysed for insecticide resistance and the data disseminated to growers via a resistance bulletin. These data are generated by the biochemical analysis of individuals for two major resistance phenotypes: (i) elevated carboxylesterase and (ii) modified acetylcholinesterase (MACE). 3,The development of new polymerase chain reaction (PCR)-based technologies using fluorescently labelled probes has allowed other resistance mechanisms, such as knockdown resistance to pyrethroids (kdr/super-kdr), to be detected and has greatly increased the speed and accuracy of resistance monitoring. Unfortunately, these newer PCR-based assays are incompatible with the older biochemical assays. 4,The present study describes the development and testing of new compatible methods for detecting elevated carboxylesterases and MACE for use on M. persicae caught in the field or suction traps. 5,These new tests have significant advantages over present methodologies by allowing individual aphids to be tested for three resistance mechanisms quickly and accurately on a single platform. [source] Recent clinical findings with memantine should not mean that the idea of neuroprotection in glaucoma is abandonedACTA OPHTHALMOLOGICA, Issue 4 2009Neville N. Osborne Abstract. Loss of vision in primary open-angle glaucoma (glaucoma) is caused by retinal ganglion cells dying at a seemingly steady and variable rate in different patients. Present treatments for all glaucoma patients are inadequate and a goal to rectify this is to discover appropriate drugs or chemicals (neuroprotectants) that can be taken orally to slow down retinal ganglion cell death and have negligible side-effects. It was therefore of great disappointment to learn earlier this year that the one clinical trial conducted to test the efficacy of memantine as a neuroprotectant for glaucoma was unsuccessful. In this article, I consider the mechanisms by which retinal ganglion cells may die in glaucoma and suggest that memantine may have benefited patients taking it but to a level that was difficult to detect with present methodologies. Ganglion cells are induced to die by different triggers in glaucoma, suggesting that neuroprotectants with multiple modes of actions are likely to reveal clearer results than was found for memantine. Therefore, the idea of neuroprotection in glaucoma must not be abandoned. [source] A micromechanical study of rolling and sliding contacts in assemblies of oval granulesINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 5 2003Hossein M. Shodja Abstract The evolution of the microstructure of an assembly of cohesionless granular materials with associated pores, which carry the overall applied stresses through frictional contacts is a complex phenomenon. The macroscopic flow of such materials take place by the virtue of the relative rolling and sliding of the grains on the micro-scale. A new discrete element method for biaxial compression simulations of random assemblies of oval particles with mixed sizes is introduced. During the course of deformation, the new positions of the grains are determined by employing the static equilibrium equations. A key aspect of the method is that, it is formulated for ellipse cross-sectional particles, hence desirable inherent anisotropies are possible. A robust algorithm for the determination of the contact points between neighbouring grains is given. Employing the present methodology, many aspects of the behaviour of two-dimensional assemblies of oval cross-sectional rods have been successfully addressed. The effects of initial void ratio, interparticle friction angle, aspect ratio, and bedding angle on the rolling and sliding contacts are examined. The distribution of normals to the rolling and sliding contacts have different patterns and are concentrated along directions, which are approximately perpendicular to one another. On the other hand, the distribution of all contact normals (combined rolling and sliding) are close to that of rolling contacts, which confirm that rolling is the dominant mechanism. This phenomenon becomes more pronounced for higher intergranular friction angle. Characteristics of the rolling and sliding contacts are also discussed in the context of the force angle, which is the inclination of contact force with respect to the contact normal. Copyright © 2003 John Wiley & Sons, Ltd. [source] F-bar-based linear triangles and tetrahedra for finite strain analysis of nearly incompressible solids.INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 3 2005Part I: formulation, benchmarking Abstract This paper proposes a new technique which allows the use of simplex finite elements (linear triangles in 2D and linear tetrahedra in 3D) in the large strain analysis of nearly incompressible solids. The new technique extends the F-bar method proposed by de Souza Neto et al. (Int. J. Solids and Struct. 1996; 33: 3277,3296) and is conceptually very simple: It relies on the enforcement of (near-) incompressibility over a patch of simplex elements (rather than the point-wise enforcement of conventional displacement-based finite elements). Within the framework of the F-bar method, this is achieved by assuming, for each element of a mesh, a modified (F-bar) deformation gradient whose volumetric component is defined as the volume change ratio of a pre-defined patch of elements. The resulting constraint relaxation effectively overcomes volumetric locking and allows the successful use of simplex elements under finite strain near-incompressibility. As the original F-bar procedure, the present methodology preserves the displacement-based structure of the finite element equations as well as the strain-driven format of standard algorithms for numerical integration of path-dependent constitutive equations and can be used regardless of the constitutive model adopted. The new elements are implemented within an implicit quasi-static environment. In this context, a closed form expression for the exact tangent stiffness of the new elements is derived. This allows the use of the full Newton,Raphson scheme for equilibrium iterations. The performance of the proposed elements is assessed by means of a comprehensive set of benchmarking two- and three-dimensional numerical examples. Copyright © 2005 John Wiley & Sons, Ltd. [source] Thermodynamic analysis of subcooling and superheating effects of alternative refrigerants for vapour compression refrigeration cyclesINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 5 2006encan Abstract This paper presents a computer-based first law and exergy analysis applied to vapour compression refrigeration systems for determining subcooling and superheating effects of environmentally safe new refrigerants. Three refrigerants are considered: R134a, R407c and R410a. It is found that subcooling and superheating temperatures directly influence the system performance as both condenser and evaporator temperatures are affected. The thermodynamic properties of the refrigerants are formulated using artificial neural network (ANN) methodology. Six ANNs were trained to predict various properties of the three refrigerants. The training and validation of the ANNs were performed with good accuracy. The correlation coefficient obtained when unknown data were used to the networks were found to be equal or very near to 1 which is very satisfactory. Additionally, the present methodology proved to be much better than the linear multiple regression analysis. From the analysis of the results it is found that condenser and evaporator temperatures have strong effects on coefficient of performance (COP) and system irreversibility. Also both subcooling and superheating affect the system performance. This effect is similar for R134a and R407c, and different for R410a. Copyright © 2005 John Wiley & Sons, Ltd. [source] Tutorial on Computational Linguistic PhylogenyLINGUISTICS & LANGUAGE COMPASS (ELECTRONIC), Issue 5 2008Johanna Nichols Over the last 10 or more years, there has been a tremendous increase in the use of computational techniques (many of which come directly from biology) for estimating evolutionary histories (i.e., phylogenies) of languages. This tutorial surveys the different methods and different types of linguistic data that have been used to estimate phylogenies, explains the scientific and mathematical foundations of phylogenetic estimation, and presents methodologies for evaluating a phylogeny estimation method. [source] Inequality Aversion versus Risk AversionECONOMICA, Issue 277 2003Yoram Kroll Inequality aversion and risk-aversion are widely assumed in economic models; however existing economic literature fails to distinguish between the two. This paper presents methodology and a laboratory experiment, which separates inequality aversion from risk aversion. In a set of laboratory experiments, subjects had to choose between two risky alternatives which pay meaningful prizes with the same individual risk but different levels of egalitarianism. Thus, the choice of the more egalitarian alternative implies a higher level of inequality aversion. The experiment was conducted among children, some of whom live on a communal system (kibbutz) and some in the city. [source] Flexible Maximum Likelihood Methods for Bivariate Proportional Hazards ModelsBIOMETRICS, Issue 4 2003Wenqing He Summary. This article presents methodology for multivariate proportional hazards (PH) regression models. The methods employ flexible piecewise constant or spline specifications for baseline hazard functions in either marginal or conditional PH models, along with assumptions about the association among lifetimes. Because the models are parametric, ordinary maximum likelihood can be applied; it is able to deal easily with such data features as interval censoring or sequentially observed lifetimes, unlike existing semiparametric methods. A bivariate Clayton model (1978, Biometrika65, 141,151) is used to illustrate the approach taken. Because a parametric assumption about association is made, efficiency and robustness comparisons are made between estimation based on the bivariate Clayton model and "working independence" methods that specify only marginal distributions for each lifetime variable. [source] | ||||||||||