Behavioral control and resiliency in the onset of alcohol and illicit drug use: a prospective study from preschool to adolescence

The developmental trajectories of behavioral control and resiliency from early childhood to adolescence and their effects on early onset of substance use were examined. Behavioral control is the tendency to express or contain one's impulses and behaviors. Resiliency is the ability to adapt flexibly one's characteristic level of control in response to the environment. Study participants were 514 children of alcoholics and matched controls from a longitudinal community sample (Time 1 age in years: M =4.32, SD =0.89). Children with slower rates of increase in behavioral control were more likely to use alcohol and other drugs in adolescence. Children with higher initial levels of resiliency were less likely to begin using alcohol.     

Characterising the impact performance of field hockey sticks

Published research on field hockey equipment is scarce. The aim of this research was to investigate methods for characterising the impact performance of field hockey sticks. Three sticks were used with fundamental frequencies in the range 74?C154?Hz. Striking an initially still ball with a stick was identified as the preferred method for characterising performance. Impacts were simulated at mean velocities of 19?m/s at toe and 16?m/s at the shaft. The mean apparent coefficient of restitution and standard deviation were ?0.32?±?0.05 at the toe and ?0.18?±?0.02 at the shaft. The foundation work presented here provides the foundations for developing a methodology for characterising the impact performance of field hockey sticks.     

Practicing a maximal performance task: a cooperative strategy for muscle activity

The effect of practice on predicting elbow flexion movement time was studied. Participants (N = 18) performed 400 elbow flexion trials to a target in the horizontal plane. The trials were distributed equally over four sessions. The goal was to decrease the movement time (MT) for the same degree of accuracy. The electromyographic (EMG) activity of the biceps and triceps brachii was monitored with standard Beckman Ag/AgCl surface electrodes. The EMG measures formed two variable sets within one prediction equation. One variable set was composed of the onset of muscle activity relative to the start of movement (motor time) and the duration of muscle activity. The other variable set consisted of the mean amplitude value of the entire burst and of the first 30 ms (Q30) of activity. As the maximal speed of limb movement increased, the duration of muscle activity (motor time and EMG duration) decreased, and the magnitude of muscle activity (MAV and Q30) increased. Most of the change in the duration of muscle activity occurred in Session 1, while the magnitude of muscle activity continued to increase until Session 3. Multiple regression analysis revealed a cooperative strategy between the magnitude and duration of muscle activity. Early in learning, participants adjusted the magnitude of muscle activity to increase limb movement speed. As practice continued, alterations in the duration of muscle activity became more important, while the magnitude changes were less involved. Late in learning, both dimensions of muscle activity were used to decrease MT. We suggest that the interplay between the magnitude and duration of muscle activity may be due to: (a) cognitive factors related to the division of attention in a motor skill, (b) an increase in the frequency of motor unit firing that affects both dimensions of muscle activity, or (c) some combination of (a) and (b).     

Knowledge and Skills of the Lamaze Certified Childbirth Educator: Results of a Job Task Analysis

Content validity of certification examinations is demonstrated over time with comprehensive job analyses conducted and analyzed by experts, with data gathered from stakeholders. In November 2011, the Lamaze International Certification Council conducted a job analysis update of the 2002 job analysis survey. This article presents the background, methodology, and findings of the job analysis. Changes in the test blueprint based on these findings are presented.     

Individual differences in navigation between sharable content objects—an evaluation study of a learning module prototype

In this article, we report the design and evaluation of a prototype for learning modules compliant to the SCORM standard. This prototype is especially developed for the subject matter of process systems engineering and features a novel process control display for the navigation between Sharable Content Objects. In a controlled field study, N=18 undergraduate students interacted with the module for a period of 40 minutes. The relations between individual differences in learner characteristics, navigation, and learning outcome were considered. Interaction with the module had a strong positive effect on learning outcome. Individual differences in learning outcome were significantly affected by individual differences in intrinsic motivation, computer experience and navigation behaviour.