How do we do this: learning how to teach socioscientific issues

Cultural Studies of Science Education - Socioscientific Issues (SSI) provide a strong framework for engaging students and teachers in meaningful and relevant scientific discourse in the development...     

The influence of deformation on barbell mechanics during the clean pull

For simplicity of biomechanical analyses, the weightlifting barbell is typically modelled as a rigid, nondeformable object. Most coaches and weightlifters, however, are aware of the elastic nature of the barbell, and its influence on the successful completion of lifting attempts. Variables such as velocity, work performed, and power output are indicators of the quality of performance during the snatch, clean, and related weightlifting pulling movements. The aim of this study was to establish whether differences exist in determining these biomechanical parameters when the centre of the barbell is analysed compared with each end of the barbell. Nine men performed three maximal-effort repetitions in the clean pull exercise at 85% of their self-reported single repetition maximum (1-RM) clean (90-155 kg) using a barbell instrumented for mechanical analysis. Results indicated that peak barbell speed was 5-30% (P < 0.05) lower for the centre of the barbell than the ends. Although differences (P < 0.05) in kinetic and potential energy were found between the centre and ends of the bar, differences between total work performed were small (< 6%; P < 0.05) and no differences were observed for average power (P > 0.05). Although approximately the same work and power occur for the centre and ends of the barbell, they manifest as different kinematics as a result of the elastic nature of the equipment. The elastic characteristics should be considered when selecting instrumentation and variables for research involving barbells. Coaches should be aware of the elasticity of barbells, including selecting appropriate viewing angles as well as understanding how deformation may affect the ends of the barbell relative to the centre.     

Visual complexity in infancy: contour or numerosity?

To examine the relationship between visual attention in infancy and the stimulus variables of contour and numerosity, 2- and 4-month-old infants were placed in 3 experimental conditions. In the first condition, the patterns shown to the infants varied in amount of contour but had an equal number of elements; in the second, they varied in numerosity but had an equal amount of contour; and in the third, the patterns varied in both numerosity and contour. The results showed that contour and numerosity acting in tandem are responsible for the age-complexity shift observed in previous investigations of infant attention.     

Non-Linear Functional Relations and Superposition Principles in Viscoelasticity

Non-linear constitutive functional equations for isotropic viscoelastic materials with small and finite deformations are derived on the basis of tensorial expansions. These equations express the first-order as well as simple and joint second-order effects. Further, the corresponding non-linear superposition principles are formulated.