Is 27 a big number? Correlational and causal connections among numerical categorization, number line estimation, and numerical magnitude comparison

This study examined the generality of the logarithmic to linear transition in children's representations of numerical magnitudes and the role of subjective categorization of numbers in the acquisition of more advanced understanding. Experiment 1 (49 girls and 41 boys, ages 5-8 years) suggested parallel transitions from kindergarten to second grade in the representations used to perform number line estimation, numerical categorization, and numerical magnitude comparison tasks. Individual differences within each grade in proficiency for the three tasks were strongly related. Experiment 2 (27 girls and 13 boys, ages 5-6 years) replicated results from Experiment 1 and demonstrated a causal role of changes in categorization in eliciting changes in number line estimation. Reasons were proposed for the parallel developmental changes across tasks, the consistent individual differences, and the relation between improved categorization of numbers and increasingly linear representations.     

Carl Schmidt -- a chemical tourist in Victorian Britain

Carl Schmidt is one of the founders of modern biochemistry. He wrote numerous scientific publications, and left future generations several important documents that included two extensive hand-written travel reports from 1857 and 1864. In these, Schmidt paints a lively and impressive picture of industry in Victorian Britain from a personal perspective, showing this key period of European economic history in a unique light. Thus, it is rewarding to follow Schmidt on his travels through Britain, which he regarded as the workshop of the world and a shining but unattainable example for the industrial development of his home country.     

Effect of Certain Antibiotics Against Filarial Parasite <Emphasis Type="Italic">Brugia malayi</Emphasis> In Vitro: Possible Role of Oxidative Stress

WHO-Tropical Disease Research scheme highlighted the need for development of new anti-filarial drugs. Certain antibiotics have recently been found effective against Wolbachia, co-existing symbiotically with filarial parasites. Inflammatory response entails oxidative mechanism to educe direct anti-microbial effect. In the present study microfilariae were maintained in vitro in medium supplemented with varying concentrations of tetracycline, doxycycline (20–100 μg/ml) or ciprofloxacin (50–250 μg/ml) separately to find out any involvement of oxidative mechanism in the anti-filarial effect of these antibiotics. Loss of motility of the microfilariae was measured after 48 h and correlated with the levels of MDA, nitric oxide and protein-carbonylation. Significant loss of microfilarial motility was recorded with increasing concentration of tetracycline and doxycycline but with ciprofloxacin the effect was not marked. Agents with high antifilarial activity revealed significant association with oxidative parameters in a dose dependent manner. The result suggests that oxidative effect might be exploited to design novel antifilarial drug candidate.     

Probing the allocation of attention in implicit (motor) learning

We investigated the attention demands associated with implicit and explicit (motor) learning and performance using a probe reaction time paradigm. Two groups of participants learned a golf putting task over eight blocks of 50 trials performed from different distances. One group (errorless learning) began putting from the shortest distance (25 cm) and moved progressively back to the furthest distance (200 cm). A second group (errorful learning) began putting from the furthest distance (200 cm) and moved progressively closer (25 cm). Retention tests were used to assess learning in the two conditions, followed by transfer tests in which participants used either an unusual putter or a very unusual putter. Transfer to the unusual putters had an equivalent effect on the performance of both errorless and errorful learners, but probe reaction times were unaffected in the errorless learners, suggesting that execution of their movements was associated with reduced attention demands. Reducing errors during initial learning trials may encourage an implicit mode of learning and lower the demand for cognitive resources in subsequent performance.     

Benefits of an external focus of attention: common coding or conscious processing?

We conducted two experiments to assess the effect attentional focus has on learning a complex motor skill and subsequent performance under secondary task loading. Participants in Experiment 1 learnt a golf putting task (300 practice trials) with a single instruction to either focus on their hands (internal focus) or the movement of the putter (external focus). No group differences were evident during learning or retention. Differences between the groups were only apparent under secondary task load; the external group's performance remained robust, while the internal group suffered a drop in performance. Verbal protocols demonstrated that the internal group accumulated significantly more internal knowledge and more task-relevant knowledge in general than the external group. Experiment 2 was designed to establish whether greater internal focus knowledge or greater explicit rule build up in general was responsible for performance breakdown. Two groups were presented with a set of six internal or external rules. Again, no performance differences were found during learning or retention. During the secondary task, both groups experienced performance deterioration. It was concluded that accumulation of explicit rules to guide performance was responsible for the internal group's breakdown in performance under secondary task loading and may be responsible for some of the performance differences reported previously.     

Cross-lagged relationships among leisure-time exercise and perceived stress in blue-collar workers

Blue-collar workers (N = 203) from a large food-processing plant in the southwestern U.S. completed measures of perceived stress and leisure-time exercise at an initial test session in addition to a 2-month follow-up session. Mean age of the sample participants equaled 43.61 (SD = 9.79), and 69.5% of the sample were male, 71.4% were Caucasian, and 74.9% were married/cohabitating. Structural equation modeling was employed to examine the cross-lagged relationships between perceived stress and leisure-time exercise at these time points, controlling for gender, marital status, age, and yearly household income. Results indicated that a model with a path from perceptions of Time 1 stress to Time 2 exercise frequency was most parsimonious and provided acceptable model fit, suggesting that perceptions of stress are related to reductions in exercise participation in this population. However, there was little support for a relationship between Time 1 exercise participation and Time 2 perceived stress.