Changes in mechanical properties of sprinting during repeated sprint in elite rugby sevens athletes

This study aimed to analyse fatigue-induced changes in mechanical sprinting properties during a specific repeated-sprint test in elite rugby sevens athletes. Twenty elite rugby sevens players performed ten 40?m sprints on a 30?s cycle with participant’s running back and forth in a marked lane. Radar was used to assess maximal overground sprint performance over each 40?m. Macroscopic mechanical properties (maximal horizontal force (F₀), maximal horizontal power (P_max), maximal ratio of horizontal force (RF_peak), decrease in the ratio of horizontal-to-total force (D_RF), total force and maximal sprinting velocity (v₀)) were drawn from horizontal force velocity relationships, using a validated method applied to the speed–time data. Fatigue-induced changes were analysed comparing the first sprint to an average of 2^nd-4^th, 5^th-7^th and 8^th-10^th. Repeated-sprint ability (RSA) testing induced substantial changes in the maximal velocity component, with a decrease (–15%) in v₀ (effect size (ES)?=?–2.46 to –4.98), and to a lower extent (–5.9%) in the maximal force component F₀ (ES?=?–0.59). D_RF moderately decreased (14%; ES=–0.76–1.11), and RF_peak largely decreased in the later sprints (ES?=?–0.32 to –1.27). Fatigue observed in this RSA test appeared to have a greater effect on the technical ability to produce horizontal force at high velocities, likely due to an alteration in the ability to maintain horizontally oriented force application when velocity increases rather than during the initial acceleration phase, but also the overall force production capacity. The ability to maintain forward-oriented force at high velocities is of central importance for identifying fatigue and monitoring load.     

How did Light Acquire a Velocity?

We discuss how light acquired a velocity through history, from the ancient Greeks to the early modern era. Combining abstract debates, models of light, practical needs, planned research and chance, this history illustrates several key points that should be brought out in science education.     

Évaluation-sondage dans le premier cycle (12–16 ans)

Sans résuméI.R.E.M. de Rouen     

Are implicit learning abilities sensitive to the type of material to be processed? Study on typical readers and children with dyslexia

This study aims to examine the impact of the linguistic nature of the material to be tracked in a serial reaction time task on the performance of typical readers and children with dyslexia. In doing so, we wished to detect eventual differences in the mobilisation of implicit learning skills between typical readers according to their experience with the written word (8‐ vs 10‐year‐olds) on the one hand, and between typical readers and children with dyslexia, on the other hand. Experiment 1 confirms the efficiency of implicit sequence learning in typical readers regardless of the nature of the item being tracked. Experiment 2 indicates that the sequence learning of children with dyslexia is sensitive to the nature of the target. Children with dyslexia show differences in the evolution of response times according to the nature of the item to be tracked.     

Predictors of placement for children who initially remained in their homes after an investigation for abuse or neglect

Objective

To examine the frequency and predictors of out-of-home placement in a 30-month follow-up for a nationally representative sample of children investigated for a report of maltreatment who remained in their homes following the index child welfare report.

Methods

Data came from the National Survey of Child and Adolescent Well-being (NSCAW), a 3-year longitudinal study of 5,501 youth 0-14 years old referred to child welfare agencies for potential maltreatment between 10/1999 and 12/2000. These analyses focused on the children who had not been placed out-of-home at the baseline interview and examined child, family and case characteristics as predictors of subsequent out-of-home placement. Weighted logistic regression models were used to determine which baseline characteristics were related to out-of-home placement in the follow-up.

Results

For the total study sample, predictors of placement in the 30-month follow-up period included elevated Conflict Tactics Scale scores, prior history of child welfare involvement, high family risk scores and caseworkers’ assessment of likelihood of re-report without receipt of services. Higher family income was protective. For children without any prior child welfare history (incident cases), younger children, low family income and a high family risk score were strongly related to subsequent placement but receipt of services and case workers’ assessments were not.

Conclusions/practice implications

Family risk variables are strongly related to out-of-home placement in a 30-month follow-up, but receipt of child welfare services is not related to further placements. Considering family risk factors and income, 25% of the children who lived in poor families, with high family risk scores, were subsequently placed out-of-home, even among children in families who received child welfare services. Given that relevant evidence-based interventions are available for these families, more widespread tests of their use should be explored to understand whether their use could make a substantial difference in the lives of vulnerable children.     

Neuromyths Among Teachers and Student Teachers

Many so‐called brain‐based educational approaches have been strongly criticized for their lack of empirical support and occasionally for their use of pseudoscientific concepts. As a result, several use the term neuromyths to refer to false beliefs or misinterpretations regarding neuroscientific facts. We surveyed both teachers and student teachers concerning their agreement toward hemispheric dominance, modality dominance, and the Brain Gym© method. Results suggest that teachers as well as student teachers believe in the reality of hemispheric and modality dominance but only a few were aware of the Brain Gym© method. Correlation analyses show moderate relationships across different beliefs and/or their perceived benefits in education. Teachers believed more than student teachers in hemispheric dominance and its pedagogical relevance. Together with other studies, the results suggest that teachers and student teachers could benefit from appropriate training in this new field of research.     

University students＇ conceptions about the concept of gene： Interest of historical approach

Concepts of genetics are often difficult to teach, specifically the central concept of gene. Even the scientists disagree when defining this concept. This paper investigates university students＇ understanding about the gene and its functions. The results show the dominance of two conceptions of the gene： the Neoclassical model and the Mendelian model. The existence of hybrid conceptions and the lack of the modern model show that students are unable to mobilize the knowledge taught in biology. These results suggest to improve the teaching methods of genetics, for instance, by developing activities that bring students face to face with their conceptions.