Study of conservation and recurrence of Runge–Kutta discontinuous Galerkin schemes for Vlasov–Poisson systems

In this paper we consider Runge–Kutta discontinuous Galerkin (RKDG) schemes for Vlasov–Poisson systems that model collisionless plasmas. One-dimensional systems are emphasized. The RKDG method, originally devised to solve conservation laws, is seen to have excellent conservation properties, be readily designed for arbitrary order of accuracy, and capable of being used with a positivity-preserving limiter that guarantees positivity of the distribution functions. The RKDG solver for the Vlasov equation is the main focus, while the electric field is obtained through the classical representation by Green’s function for the Poisson equation. A rigorous study of recurrence of the DG methods is presented by Fourier analysis, and the impact of different polynomial spaces and the positivity-preserving limiters on the quality of the solutions is ascertained. Several benchmark test problems, such as Landau damping, the two-stream instability, and the Kinetic Electro static Electron Nonlinear wave, are given.     

Mapping dislocation nucleation behavior from bimetal interfaces

Interfaces between two dissimilar metals have been observed to exhibit a range of atomic structures, from atomically flat to atomically stepped. Using atomic-scale simulation and theory, we study the influence of the intrinsic bimetal interface structure on the nucleation of lattice dislocations. Interface structure is found to have a strong effect on which dislocations are nucleated and the type of nucleation site. We develop a theoretical model that provides criteria for predicting these effects based on key structural relationships between the interface and adjoining crystals. In recognition of these critical conditions, we construct a map that identifies the most likely nucleation site from a given interface. The theory and map developed here can guide efforts to tune interface structures for controlling the strength and deformation of heterogeneous materials.     

The development of compression damage zones in fibrous composites

Recent experimental work (Narayanan S, Schadler LS. Mechanisms of kink band formation in graphite/epoxy compsites: a micromechanical experimental study. Comp Sci Technol 1999; 59:2201-13) suggests that kink bands in unidirectional continuous carbon fiber reinforced polymer composites initiate from damage zones formed under axial compressive loads. A damage zone consists of a cluster of locally crushed fibers and broken fibers, that are often fractured at an angle, θ > 0°, normal to the fiber axis. Typically, under compressive loads, fiber breaks in damage zones form roughly along a plane at an angle φ, normal to the fiber axis. These damage zones produce stress concentrations which can lead to instabilities in the nearby fiber and matrix and initiate microbuckling and kink bands. This paper extends a micromechanical influence function technique based on earlier shear lag fiber composite models. Our modified technique calculates the fiber axial and matrix shear stress concentrations due to multiple angled and crushed fibers in arbitrary configurations. Modeling reveals that angled or ‘shear’ breaks (θ > 0°) can lead to higher shear stress concentrations in the matrix than transverse breaks (θ=0°). Also we find that the damage zone is more likely to form at an angle φ, which is greater than that of its individual fiber breaks, θ. When φ is slightly greater than θ, the shear stress in the surrounding matrix regions within the damage zone achieves a maximum, potentially weakening the matrix and interface and consequently leading to kink band formation. Monte Carlo simulations incorporating this stress analysis predict that the initiation and propagation of crushed and angled breaks progress roughly along an angle, φ ≈ 17° in a linear elastic system. When possible, our model results are compared to strain measurements of fiber composites under compression obtained by Narayanan and Schadler using micro-Raman spectroscopy (MRS).     

Violence in close relationships—development of a research area: Comment on Archer (2000).

A brief history of empirical research on violence in close relationships is presented. Assumptions of and conclusions made by feminist researchers about the problems of battered wives are reviewed. It is argued that their focus on marital violence as a form of aggression against women by men and their concern for severely beaten wives may have caused them to ignore high levels of female violence in marriage and dating. J. Archer's (see record 2000-15524-001) meta-analysis of studies of marital and dating violence showed that both sexes display violence in these relationships, although women are more likely to be injured. An expansion of Archer's definition of heterosexual violence (or violence in close relationships) to include sexual aggression and stalking is suggested. Reasons for relatively high levels of female violence in close relationships relative to violence toward strangers are briefly discussed. It is argued that more attention needs to be given to male victims of violence from their partners. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nutritional and commercial quality of the striped venus clam, Chamelea gallina, from the Adriatic sea

Nutritional quality parameters (proximate and mineral composition, contents of glycogen, fatty acids, cholesterol, plant sterols, fat-soluble vitamins, carotenes) and ecophysiological and commercial quality indicators (Condition Index, percent content of meat and intervalvar fluid) of the striped venus clam, Chamelea gallina, from the central Adriatic coast of Italy were studied at seasonal intervals over a 1-year period. Contents of protein (8.55–10.7 g/100 g), total lipid (0.73–1.59 g/100 g), glycogen (2.25–4.96 g/100 g) and non-protein nitrogen (0.54–0.78 g/100 g) varied significantly during the year, reaching the highest values in winter, in coincidence with a peak of Condition Index. Gas chromatography of total lipids showed high percentages of n − 3 polyunsaturated fatty acids (33.7–41.9% of total fatty acids), in particular eicosapentaenoic (8.16–20.0% of total fatty acids) and docosahexaenoic acids (12.5–20.3% of total fatty acids) and low levels of total n − 6 polyunsaturated fatty acids (3.61–7.87% of total fatty acids). HPLC analysis of the unsaponifiable lipids showed low levels of cholesterol, the dominant sterol (28.3–34.2 mg/ 100 g), and variable amounts of plant sterols (stigmasterol + campesterol, β-sitosterol, fucosterol + brassicasterol), α-tocopherol and carotenes.     

Mental health services for homeless mentally ill persons: Federal initiatives and current service trends.

Recent research suggests that approximately one third of the population of homeless single adults suffer from severe mental illnesses. Despite multiple health, mental health, and social welfare needs, this population is often unable to obtain necessary housing and community-based services. For this reason, since 1982, the National Institute of Mental Health (NIMH) has undertaken a number of federal initiatives to encourage research and assist states and localities in improving services focused on this vulnerable subgroup of the homeless population. This article describes the target population, NIMH research findings, and current mental health programs—with particular emphasis on two mental health programs established under the Stewart B. McKinney Homeless Assistance Act. Proposed future directions for federal research and evaluation efforts in this area are also discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Automated targeting for inter-plant water integration

Apart from in-plant water recovery, inter-plant water integration (IPWI) offers another promising mean for the reduction of fresh water and wastewater flowrates for process plants. This paper extends the automated targeting technique that was developed for single water network into IPWI. This optimisation-based technique is based on the concept of pinch analysis, which enables the setting of various network targets prior to detailed design. The automated targeting technique is formulated as a linear programming model for which global optimum is guaranteed. The proposed technique is demonstrated using several industrial and literature examples.     

Memory stages and brain asymmetry in chick learning.

Stages of formation of memory and the roles of different forebrain structures in memory formation were investigated by injecting various agents into the brains of chicks close to the time of peck-avoidance training. With L-glutamate injected bilaterally into the hyperstriatum 5 min pretraining, retention was good 1 min posttraining but significantly impaired at 5 min and each subsequent time point from 10 min to 24 hr. With ouabain, retention declined more slowly, showing significant impairment at 15 min and thereafter. With any of 3 protein synthesis inhibitors, retention was still good 60 min posttraining but significantly impaired at 90 min. The 3 time courses of decline of retention are consistent with hypotheses of 3 sequentially dependent stages of memory formation. It appears that both the medial hyperstriatum and the lateral neostriatum are required for formation of memory. Agents that are specific for a presumed stage of memory formation and whose action is restricted spatially should help reveal the roles of different brain structures in different stages of memory formation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Issues to consider in conducting nonsexist psychological research: A guide for researchers.

Discusses the operation of sexism in all areas of psychological research, from broad conceptual issues to narrow methodological concerns. It is argued that sexism, in the form of unexamined assumptions about the sexes and unequal treatment of males and females may enter psychological research at any phase of a research project. Three major types of barriers to sex-fair research are identified: excessive confidence in traditional methods of research, bias in explanatory systems, and inappropriate conceptualization and operationalization. A series of recommendations are offered to eliminate some of the most common forms of sexist bias in research and to stimulate critical discussion of practices within psychology that encourage or fail to challenge sexist bias. (103 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)