Effect of hand paddles and parachute on the index of coordination of competitive crawl-strokers

We investigated the effects of hand paddles and parachute on the relative duration of stroke phases and index of coordination of competitive crawl-strokers. Eleven male-swimmers (age: 21.9 ± 4.5 years; 50-m best time: 24.23 ± 0.75 s) were evaluated in four maximal-intensity conditions: without equipment, with hand paddles, with parachute, and with both hand paddles and parachute. Relative stroke phase duration of each arm, swimming velocity, and stroke rate were analysed from video (60 Hz). The index of coordination was quantified based on the lag time between propulsive phases of each arm, which defined the coordination mode as catch-up, opposition or superposition. The stroke rate decreased in all conditions (P < 0.05) and swimming velocity decreased with parachute and with paddles + parachutes (P < 0.05). The coordination mode changed from catch-up in free swimming (-2.3 ± 5.0%) to opposition with paddles (-0.2 ± 3.8%), parachute (0.1 ± 3.1%), and paddles + parachute (0.0 ± 3.2%). Despite these variations, no significant differences were observed in relative duration of right and left arm-stroke phases, or in index of coordination. We conclude that the external resistances analysed do not significantly influence stroke phase organization, but, as a chronic effect, may lead to greater propulsive continuity.     

The impact of different types of physical activity on total and regional bone mineral density in young Brazilian athletes

Bone turnover is affected by exercise throughout the lifespan, especially during childhood and adolescence. The objective of this study was to investigate the impact of different sports on total and regional bone mineral density in male Brazilian adolescent athletes. Forty-six adolescents aged 10-18 years participated in the study: 12 swimmers, 10 tennis players, 10 soccer players, and 14 sedentary individuals. The athletes had engaged in physical activities for more than 10 h per week in the previous 6 months. Bone mineral density of the lumbar spine (L1-L4), left proximal femur region, and whole body was evaluated by dual-energy X-ray absorptiometry. Results showed higher mean values in the proximal femur region of tennis and soccer players (1.02 ± 0.18; 0.96 ± 0.16, respectively) than swimmers and controls (0.91 ± 0.14 and 0.87 ± 0.06, respectively) (P < 0.05). In relation to the impact of sporting activities based on bone age determination, we observed significant differences in bone mineral density at all evaluated sites at the end of puberty (16-18 years) compared with 10-12 years, with increases of 78% in the lumbar spine, 47% in the proximal femur, and 38% in the whole body.     

Can self-esteem protect against the deleterious consequences of self-objectification for mood and body satisfaction in physically active female university students?

Using objectification theory (Fredrickson & Roberts, 1997), this study tested the interaction between self-objectification, appearance evaluation, and self-esteem in predicting body satisfaction and mood states. Participants (N = 93) were physically active female university students. State self-objectification was manipulated by participants wearing tight revealing exercise attire (experimental condition) or baggy exercise clothes (control condition). Significant interactions emerged predicting depression, anger, fatness, and satisfaction with body shape and size. For participants in the self-objectification condition who had low (as opposed to high) appearance evaluation, low self-esteem was associated with high depression, anger, and fatness and low satisfaction with body shape and size. In contrast, for participants with high self-esteem, these mood and body satisfaction states were more favorable irrespective of their levels of appearance evaluation. For female exercisers, self-esteem-enhancing strategies may protect against some of the negative outcomes of self-objectification.     

Masculinity, moral atmosphere, and moral functioning of high school football players

In order to identify factors associated with on-field moral functioning among student athletes within the unique context of football, we examined masculine gender role conflict, moral atmosphere, and athletic identity. Using structural equation modeling to assess survey data from 204 high school football players, results demonstrated that moral atmosphere (i.e., the influence of coaches and teammates) was significantly associated with participants' process of on-field moral functioning across the levels of judgment, intention, and behavior. Neither masculine gender role conflict nor athletic identity significantly predicted moral functioning, but the results indicated that participants' identification with the athlete role significantly predicted conflict with socialized gender roles. Results suggest that in the aggressive and violent sport of football, coaches can have a direct influence on players' moral functioning process. Coaches can also have an indirect effect by influencing all the players so that a culture of ethical play can be cultivated among teammates and spread from the top down.     

What is the ‘personal’ in ‘personal information’?

Ethics and Information Technology - Contemporary privacy theories and European discussions about data protection employ the notion of ‘personal information’ to designate their areas of...     

Optimum calibration of a parallel kinematic manipulator using digital indicators

This paper presents a calibration method for parallel manipulators using a measurement system specially installed on an external fixed frame. The external fixed frame is important as an error reference for calibration in certain operations, such as in the configuration of a parallel manip- ulator functioning as a machine tool where the workpiece is fixed to a worktable. The pose of the end-effector is mea- sured using three digital indicators installed on the external fixed frame. To enable measurement, the end-effector is assumed to be a plane large enough that all digital indicators could touch. The error is defined as the difference between the theoretical and actual readings of the digital indicators. The geometric parameters of the parallel manipulator are optimized to minimize this error. This calibration method is low cost and feasible for compensating geometric parameter errors for a parallel manipulator. Optimal pose selection for the calibration is achieved using a swarm intelligence search algorithm. The method is implemented on a prototype of a six degrees-of-freedom （DOFs） Gough-Stewart platform constructed to function as a machine tool.     

Implementation of the flipped classroom and its longitudinal impact on improving academic performance

Educational technology research and development - The objective has been to know the impact of the flipped classroom methodology on the academic performance of students during their training...     

A Systematic Review of Sequential Multiple-Assignment Randomized Trials in Educational Research

Educational Psychology Review - The purpose of this systematic review is to describe the state of the art of sequential multiple-assignment randomized trials in education research. An iterative,...     

Fostering parents-professional collaboration for facilitating the school inclusion of students with ASD: design of the “ToGather” web-based prototype

Educational technology research and development - In recent years, many psycho-educational technologies were studied to address the school-related difficulties encountered by students with autism...     

Work Demands and Work Resources: Testing a Model of Factors Predicting Turnover Intentions in Early Childhood Education

Early Childhood Education Journal - We studied the working conditions in Early Childhood Education and Care (ECEC). The aim was to explore how ECEC staff experience work demands and resources and...