Home About us Contact
|
Home About us Contact | ||
|
|
||
General Assessment (general + assessment)
Selected AbstractsPlasma membrane surface potential (,pm) as a determinant of ion bioavailability: A critical analysis of new and published toxicological studies and a simplified method for the computation of plant ,pmENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2006Thomas B. Kinraide Abstract Plasma membranes (PMs) are negatively charged, and this creates a negative PM surface electrical potential ,PM) that is also controlled by the ionic composition of the bathing medium. The ,PM controls the distribution of ions between the PM surface and the medium so that negative potentials increase the surface activity of cations and decrease the surface activity of anions. All cations reduce the negativity of ,PM, and these common ions are effective in the following order: Al3+ > H+ > Cu2+ > Ca2+ , Mg2+ > Na+ , K+. These ions, especially H+, Ca2+, and Mg2+, are known to reduce the uptake and biotic effectiveness of cations and to have the opposite effects on anions. Toxicologists commonly interpret the interactions between toxic cations (commonly metals) and ameliorative cations (commonly H+, Ca2+, and Mg2+) as competitions for binding sites at a PM surface ligand. The ,PM is rarely considered in this biotic ligand model, which incorporates the free ion activity model. The thesis of this article is that ,PM effects are likely to be more important to bioavailability than site-specific competition. Furthermore, ,PM effects could give the false appearance of competition even when it does not occur. The electrostatic approach can account for the bioavailability of anions, whereas the biotic ligand model cannot, and it can account for interactions among cations when competition does not occur. Finally, a simplified procedure is presented for the computation of ,PM for plants, and the possible use of ,PM in a general assessment of the bioavailability of ions is considered. [source] A longitudinal study of cannabis use and mental health from adolescence to early adulthoodADDICTION, Issue 4 2000Rob McGee Aims. To examine the longitudinal association between cannabis use and mental health. Design. Information concerning cannabis use and mental health from 15 to 21 years was available for a large sample of individuals as part of a longitudinal study from childhood to adulthood. Participants. Participants were enrolled in the Dunedin Multidisciplinary Health and Development Study, a research programme on the health, development and behaviour of a large group of New Zealanders born between 1 April 1972 and 31 March 1973. Measurements. Cannabis use and identification of mental disorder was based upon self-report as part of a general assessment of mental health using a standard diagnostic interview. Daily smoking and alcohol use at age 15 were assessed by self-report. Indices of family socio-economic status, family climate and parent - child interaction were formed using information gathered from parent report and behavioural observations over early childhood. Childhood behaviour problems were assessed by parent and teacher report. Attachment to parents was assessed in adolescence. Findings. Cross-sectional associations between cannabis use and mental disorder were significant at all three ages. Both outcome variables shared similar pathways of low socio-economic status and history of behaviour problems in childhood, and low parental attachment in adolescence. Mental disorder at age 15 led to a small but significantly elevated risk of cannabis use at age 18; by contrast, cannabis use at age 18 elevated the risk of mental disorder at age 21. The latter association reflected the extent to which cannabis dependence and other externalizing disorders at age 21 were predicted by earlier level of involvement with cannabis. Conclusions. The findings suggest that the primary causal direction leads from mental disorder to cannabis use among adolescents and the reverse in early adulthood. Both alcohol use and cigarette smoking had independent associations with later mental health disorder. [source] Immigration and femininity in Southern Europe: A gender-based psychosocial analysisJOURNAL OF COMMUNITY & APPLIED SOCIAL PSYCHOLOGY, Issue 5 2008J. M. González-González Abstract Despite the growing presence of female immigrants in Western countries, research on the subject highlights two important biases that hinder appropriate explanation of the migratory phenomenon and hence prevent adequate intervention. First, most of the research studies conducted so far focus on male migration; second, the macro-social perspective has prevailed in these areas of study since socio-economic and political aspects have taken centre stage in analyses on migratory phenomena, From a gender-based psychosocial perspective, this study addresses the migration project of 53 women from different South American countries, the Maghreb region and Eastern Europe now living in Southern Spain. For this purpose we conducted 23 in-depth interviews, and staged six discussion groups with the aim of elucidating to what extent gender-based psychosocial beliefs,stereotypes, ideology and identity,determine women's migration process. Our results suggest that the main stages in the process,deciding to emigrate, itinerary for social and labour integration in the host country, and general assessment of the migration experience,are strongly influenced by psychosociological constructs which arise as a result of female gender-typing or female profile. Copyright © 2008 John Wiley & Sons, Ltd. [source] What's Wrong With Infinite Regresses?METAPHILOSOPHY, Issue 5 2001Daniel Nolan It is almost universally believed that some infinite regresses are vicious, and also almost universally believed that some are benign. In this paper I argue that regresses can be vicious for several different sorts of reasons. Furthermore, I claim that some intuitively vicious regresses do not suffer from any of the particular aetiologies that guarantee viciousness to regresses, but are nevertheless so on the basis of considerations of parsimony. The difference between some apparently benign and some apparently vicious regresses, then, turns out to be a matter of a more general assessment of costs and benefits, making viciousness of regresses in some cases less of a local matter than is usually thought. [source] A Survey of Model Evaluation Approaches With a Tutorial on Hierarchical Bayesian MethodsCOGNITIVE SCIENCE - A MULTIDISCIPLINARY JOURNAL, Issue 8 2008Richard M. Shiffrin Abstract This article reviews current methods for evaluating models in the cognitive sciences, including theoretically based approaches, such as Bayes factors and minimum description length measures; simulation approaches, including model mimicry evaluations; and practical approaches, such as validation and generalization measures. This article argues that, although often useful in specific settings, most of these approaches are limited in their ability to give a general assessment of models. This article argues that hierarchical methods, generally, and hierarchical Bayesian methods, specifically, can provide a more thorough evaluation of models in the cognitive sciences. This article presents two worked examples of hierarchical Bayesian analyses to demonstrate how the approach addresses key questions of descriptive adequacy, parameter interference, prediction, and generalization in principled and coherent ways. [source] | ||||||||||