Composition dependence of the magnetic properties of bonded magnets of strontium hexaferrite‐polyvinyl chloride

A systematic study of the magnetic properties of strontium ferrite‐polyvinyl chloide plastoferrites as a function of composition is presented. Plastoferrites were manufactured by hot compression of a mixture of commercial powders of strontium ferrite (SrFe₁₂O₁₉) and polyvinyl chloride. In order to explain the dependence of the volumetric density and the saturation magnetization with composition, an additive model for these properties is considered. The intrinsic coercivity shows a decrease with increasing strontium ferrite content, which is interpreted as a magnetizing‐like effect due to the increasing interaction between the magnetic particles. The maximum energy products are lower than 1 MGOe and increase with the second power of the strontium ferrite content. The best maximum energy product and specific saturation magnetization were obtained for the plastoferrite with a 85 weight percentage of ferrite.     

Perceived self-efficacy, outcome-efficacy and feedback: Their effects on professors' teaching development motivation.

Examined the effects of perceived (1) self-efficacy, (2) outcome- efficacy, and (3) feedback on motivation to improve university teaching through teaching development workshops. The authors also examined the relationships between aspects of feedback. 74 university professors (aged 28–67 yrs) from the Faculties of Social Sciences and Management at the University of Calgary completed a survey to assess their perceptions of self-efficacy, outcome- efficacy, and feedback they received from their most recent student-based course evaluations. The data were analyzed separately for the 2 faculties. Measures of outcome-efficacy were positively related to motivation for both groups. For Ss in the Faculty of Social Sciences, self-efficacy was positively related to motivation. All relationships between aspects of feedback (e.g., valence with accuracy and accuracy and timeliness with effectiveness) were found to be positive. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The myth of Eve: molecular biology and human origins

It has been proposed that modern humans descended from a single woman, the "mitochondrial Eve" who lived in Africa 100,000 to 200,000 years ago. The human immune system DRB1 genes are extremely polymorphic, with gene lineages that coalesce into an ancestor who lived around 60 million years ago, a time before the divergence of the apes from the Old World monkeys. The theory of gene coalescence suggests that, throughout the last 60 million years, human ancestral populations had an effective size of 100,000 individuals or greater. Molecular evolution data favor the African origin of modern humans, but the weight of the evidence is against a population bottleneck before their emergence. The mitochondrial Eve hypothesis emanates from a confusion between gene genealogies and individual genealogies.     

Motoric and symbolic mediation in observational learning.

The observers' motoric and symbolic representations of a model's behavior are important mediators in observational learning. The observers' spontaneous use of these mediators may be influenced by their familiarity with responses performed by a model and by their intention to learn these responses. Unfamiliar observers do not have symbolic codes available for the model's responses, so they may rely on motor mimicry. Familiar observers have symbolic codes available, so they may employ those codes and, possibly, motor mimicry as mediators. Spontaneous mediation may also depend on whether observers intend to learn these responses. Three experiments with 132 undergraduates revealed that familiar observers used motoric and symbolic mediators, whereas unfamiliar observers primarily used motor mimicry. Symbolic coding facilitated familiar but not unfamiliar observers' learning; unfamiliar observers' learning was related to motor mimicry. Intention to learn increased motor mimicry but not symbolic coding. An interpretation is offered for the observers' pervasive use of motor mimicry. (3 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of oxidative stress, produced by cumene hydroperoxide, on the various steps of protein synthesis. Modifications of elongation factor-2

We have studied the effect of oxidative stress on protein synthesis in rat liver. Cumene hydroperoxide (CH) was used as an oxidant agent. The approach used was to determine the ribosomal state of aggregation and the time for assembly and release of polypeptide chains in the process of protein synthesis in rat liver in vivo. The results suggest that the elongation step is the most sensitive to CH treatment. The measurement of both carbonyl groups content and ADP-ribosylatable elongation factor 2 (EF-2), the main protein involved in the elongation step, indicates that under CH treatment EF-2 is oxidatively modified and a lower amount of active EF-2 is present. These results are corroborated by in vitro oxidation of EF-2 and could explain for the decline in the elongation step.     

Therapeutic death: A look at Oregon's law.

Oregon voters approved the first American statute authorizing physician-assisted suicide, the Oregon Death With Dignity Act, in 1994. The authors of this article identify some positive and negative psychological effects of laws such as Oregon's on patients. Generally, they conclude, on the basis of psychological theory and the available data, that laws such as Oregon's benefit patients psychologically. Undoubtedly, however, there exist important possible antitherapeutic effects on patients, and the authors hope that discussion of both therapeutic and antitherapeutic consequences will stimulate future research by social scientists in this area. (PsycINFO Database Record (c) 2010 APA, all rights reserved)