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Largest Effects (largest + effects)
Selected AbstractsHypoxia and oxidation levels of DNA and lipids in humans and animal experimental modelsIUBMB LIFE, Issue 11 2008Peter Møller Abstract The objective of this review was to evaluate the association between hypoxia and oxidative damage to DNA and lipids. Evaluation criteria encompassed specificity and validation status of the biomarkers, study design, strength of the association, dose-response relationship, biological plausibility, analogous exposures, and effect modification by intervention. The collective interpretation indicates persuasive evidence from the studies in humans for an association between hypoxia and elevated levels of oxidative damage to DNA and lipids. The levels of oxidatively generated DNA lesions and lipid peroxidation products depend on both the duration and severity of the exposure to hypoxia. Largest effects are observed with exposure to hypoxia at high altitude, but other factors, including ultraviolet light, exercise, exertion, and low intake of antioxidants, might contribute to the effect observed in subjects at high altitude. Most of the animal experimental models should be interpreted with caution because the assays for assessment of lipid peroxidation products have suboptimal validity. © 2008 IUBMB IUBMB Life, 60(11): 707,723, 2008 [source] Retraining automatic action-tendencies to approach alcohol in hazardous drinkersADDICTION, Issue 2 2010Reinout W. Wiers ABSTRACT Aims The main aim of this study was to test whether automatic action-tendencies to approach alcohol can be modified, and whether this affects drinking behaviour. Design and participants Forty-two hazardous drinkers were assigned randomly to a condition in which they were implicitly trained to avoid or to approach alcohol, using a training variety of the alcohol Approach Avoidance Test (AAT). Participants pushed or pulled a joystick in response to picture-format (landscape or portrait). The pictures depicted alcoholic or non-alcoholic drinks. Participants in the avoid-alcohol condition pushed most alcoholic and pulled most non-alcoholic drinks. For participants in the approach-alcohol condition these contingencies were reversed. After the implicit training, participants performed a taste test, including beers and soft drinks. Automatic action tendencies at post-test were assessed with the AAT, including both trained and untrained pictures, and with a different test (Implicit Association Test, IAT). We further tested effects on subjective craving. Results Action tendencies for alcohol changed in accordance with training condition, with the largest effects in the clinically relevant avoid-alcohol condition. These effects occurred outside subjective awareness and generalized to new pictures in the AAT and to an entirely different test using words, rather than pictures (IAT). In relatively heavy drinking participants who demonstrated changed action tendencies in accordance with their training condition, effects were found on drinking behaviour, with participants in the approach-alcohol condition drinking more alcohol than participants in the avoid-alcohol condition. No effect was found on subjective craving. Conclusions Retraining automatic processes may help to regain control over addictive impulses, which points to new treatment possibilities. [source] Adsorbing colloid flotation for removal of metal ions in waters from base metal minesENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2002H. Sabti Adsorbing Colloid Flotation (ACF) has been shown in laboratory experiments to be effective for the removal of heavy metals (Zn, Cu, Cd and Pb) from dilute solutions. Sodium dodecyl sulphate (SDS) and sodium oleate (NaOl) were used as surfactants in single or mixed form, with Fe(OH)3 as a flocculant for colloid formation. These reagents worked best for zinc and copper ions for a feed concentration of 50 parts per million (ppm). The removal of lead improved significantly by the use of Fe(OH)3 and NaLS (Sodium lauryl sulphate), while the best removal of cadmium was achieved by the use of Al(OH)3 and HTMABr (hexadecyltrimethylammonium bromide). Flotation experiments were conducted with feed concentrations of 50 and 500 parts per billion (ppb) and 50 ppm (parts per million). The experimental results showed that the residual concentration of metal ions decreased significantly with the decrease in the feed concentration. This could be the effect of excessive (much more than stoichiometric ratio) amounts of surfactant and flocculant, compared to the feed concentrations, required in the effective flotation of dilute feed solutions. The surfactant concentration and feed pH had the largest effects on the process, as observed in the case of cadmium removal. This can be attributed to the flocformation and flotation tendencies of the colloid-metal complexes at various solution pH and surfactant concentrations. The ACF method was applied to a number of natural drainage solutions from the metal mines at Te Aroha, New Zealand, and the experimental results demonstrate that significant removal is achieved for most of the heavy metals. [source] Effects of environmental variables on fish feeding ecology: implications for the performance of baited fishing gear and stock assessmentJOURNAL OF FISH BIOLOGY, Issue 6 2004A. W. Stoner The effectiveness of baited fishing gear ultimately depends upon behaviour of the target species , activity rhythms, feeding motivation, and sensory and locomotory abilities. While any environmental parameter that mediates feeding or locomotion can have an important influence on the active space presented by the bait and fish catchability, few biologists have considered how such variation in behaviour might affect catch per unit effort (CPUE) and the resultant stock abundance estimates or population parameters. This review reveals that environment-related variation in feeding behaviour can act through four different mechanisms: metabolic processes, sensory limitations, social interactions and direct impacts. Water temperature, light level, current velocity and ambient prey density are likely to have largest effects on fish catchability, potentially affecting variation in CPUE by a factor of ten. Feeding behaviour is also density-dependent, with both positive and negative effects. Over time and geographic space a target species can occupy wide ranges of environmental conditions, and in certain cases, spatial and temporal variation in feeding biology could have a larger impact on CPUE than patterns of abundance. Temperature, light and current can be measured with relative facility and corrections to stock assessment models are feasible. Making corrections for biological variables such as prey density and bait competitors will be more difficult because the measurements are often not practical and relationships to feeding catchability are more complex and poorly understood. There is a critical need for greater understanding of how environmental variables affect feeding-related performance of baited fishing gear. A combination of field observations and laboratory experiments will be necessary to parameterize stock assessment models that are improved to accommodate variation in fish behaviour. Otherwise, survey data could reveal more about variation in behaviour than abundance trends. [source] Maternal employment and teenage childbearing: Evidence from the PSIDJOURNAL OF POLICY ANALYSIS AND MANAGEMENT, Issue 1 2005Leonard M. LopooArticle first published online: 17 NOV 200 Over the last 30 years, the tenet of promoting self-sufficiency through work has become one of the primary objectives of many social welfare policies in the United States. Using the Panel Study of Income Dynamics, the author asks if a mother's work hours influence her daughter's teenage fertility. The findings suggest a negative relationship, with the largest effects for the daughters of mothers who work more than 1,000 hours per year. Results among AFDC recipients suggest that an increase in a mother's work hours from zero to 20 hours per week reduces her daughter's probability of a teen birth by 33 percent. © 2005 by the Association for Public Policy Analysis and Management. [source] Civic Education in Post-Apartheid South Africa: Alternative Paths to the Development of Political Knowledge and Democratic ValuesPOLITICAL PSYCHOLOGY, Issue 3 2005Steven E. Finkel Despite the proliferation of civic education programs in the emerging democracies of Latin America, Africa, and Eastern Europe, there have been few recent evaluations of the effectiveness of civics instruction in achieving changes in democratic orientations among student populations. We present findings from a study conducted in 1998 that examined the impact of democratic civic education among South African high school students. Using a battery of items to gauge democratic orientations, including measures of political knowledge, civic duty, tolerance, institutional trust, civic skills, and approval of legal forms of political participation, we find that civic education had the largest effects on political knowledge, with the magnitude of the effect being approximately twice as large as the recent Niemi and Junn (1998) finding for the United States. Exposure to civic education per se had weaker effects on democratic values and skills; for these orientations, what matters are specific factors related to the quality of instruction and the use of active pedagogical methods employed by civics instructors. Further, we find that civic education changed the structure of students' orientations: a "democratic values" dimension coalesces more strongly, and in greater distinction, from a "political competence" dimension among students exposed to civic education than among those with no such training. We discuss the implications of the findings for our theoretical understanding of the role of civic education in fostering democratic attitudes, norms, and values, as well as the practical implications of the results for the implementation and funding of civic education programs in developing democracies in the future. [source] UNEMPLOYMENT DURATION, BENEFIT DURATION AND THE BUSINESS CYCLETHE ECONOMIC JOURNAL, Issue 479 2002Olympia Bover In this paper we study the effects of unemployment benefit duration and the business cycle on unemployment duration. We construct durations for individuals entering unemployment from a longitudinal sample of Spanish men in 1987,94. Estimated discrete hazard models indicate that receipt of unemployment benefits significantly reduces the hazard of leaving unemployment. At durations of three months, when the largest effects occur, the hazard for workers without benefits is twice as large as that for workers with benefits. Favourable business conditions increase the hazard of leaving unemployment. At sample-period magnitudes, this effect is significantly smaller than that of benefit receipt. [source] Multi-site genetic modulation of monolignol biosynthesis suggests new routes for formation of syringyl lignin and wall-bound ferulic acid in alfalfa (Medicago sativa L.)THE PLANT JOURNAL, Issue 1 2006Fang Chen Summary Genes encoding seven enzymes of the monolignol pathway were independently downregulated in alfalfa (Medicago sativa) using antisense and/or RNA interference. In each case, total flux into lignin was reduced, with the largest effects arising from the downregulation of earlier enzymes in the pathway. The downregulation of l -phenylalanine ammonia-lyase, 4-coumarate 3-hydroxylase, hydroxycinnamoyl CoA quinate/shikimate hydroxycinnamoyl transferase, ferulate 5-hydroxylase or caffeic acid 3- O -methyltransferase resulted in compositional changes in lignin and wall-bound hydroxycinnamic acids consistent with the current models of the monolignol pathway. However, downregulating caffeoyl CoA 3- O -methyltransferase neither reduced syringyl (S) lignin units nor wall-bound ferulate, inconsistent with a role for this enzyme in 3- O -methylation ofS monolignol precursors and hydroxycinnamic acids. Paradoxically, lignin composition differed in plants downregulated in either cinnamate 4-hydroxylase or phenylalanine ammonia-lyase. No changes in the levels of acylated flavonoids were observed in the various transgenic lines. The current model for monolignol and ferulate biosynthesis appears to be an over-simplification, at least in alfalfa, and additional enzymes may be needed for the 3- O -methylation reactions of S lignin and ferulate biosynthesis. [source] Are expert athletes ,expert' in the cognitive laboratory?APPLIED COGNITIVE PSYCHOLOGY, Issue 6 2010A meta-analytic review of cognition, sport expertise Recent literature has demonstrated the usefulness of fitness and computer-based cognitive training as a means to enhance cognition and brain function. However, it is unclear whether the combination of fitness and cognitive training that results from years of extensive sport training also results in superior performance on tests of cognitive processes. In this study we examine, in a quantitative meta-analysis (k,=,20), the relationship between expertise in sports and laboratory-based measures of cognition. We found that athletes performed better on measures of processing speed and a category of varied attentional paradigms, and athletes from interceptive sport types and males showed the largest effects. Based on our results, more research should be done with higher-level cognitive tasks, such as tasks of executive function and more varied sub-domains of visual attention. Furthermore, future studies should incorporate more female athletes and use a diverse range of sport types and levels of expertise. Copyright © 2009 John Wiley & Sons, Ltd. [source] Hostile Attribution of Intent and Aggressive Behavior: A Meta-AnalysisCHILD DEVELOPMENT, Issue 3 2002Bram Orobio De Castro A meta-analytic review was conducted to explain divergent findings on the relation between children's aggressive behavior and hostile attribution of intent to peers. Forty-one studies with 6,017 participants were included in the analysis. Ten studies concerned representative samples from the general population, 24 studies compared nonaggressive to extremely aggressive nonreferred samples, and 7 studies compared nonreferred samples with children referred for aggressive behavior problems. A robust significant association between hostile attribution of intent and aggressive behavior was found. Effect sizes differed considerably between studies. Larger effects were associated with more severe aggressive behavior, rejection by peers as one of the selection criteria, inclusion of 8- to-12-year-old participants, and absence of control for intelligence. Video and picture presentation of stimuli were associated with smaller effect sizes than was audio presentation. Staging of actual social interactions was associated with the largest effects. The importance of understanding moderators of effect size for theory development is stressed. [source] | ||||||||||||||||