Mechanical determinants of acceleration and maximal sprinting speed in highly trained young soccer players

Abstract

The aim of the present study was to examine, in highly trained young soccer players, the mechanical horizontal determinants of acceleration (Acc) and maximal sprinting speed (MSS). Eighty-six players (14.1 ± 2.4 year) performed a 40-m sprint to assess Acc and MSS. Speed was measured with a 100-Hz radar, and theoretical maximal velocity (V₀), horizontal force (F₀) and horizontal power (P_max) were calculated. Within each age group, players were classified as high Acc/fast MSS (>2% faster than group mean), medium (between ?2% and +2%), and low/slow (>2% slower). Acc and MSS were very largely correlated (?0.79; 90% confidence limit [?0.85; ?0.71]). The determinants (multiple regression r² = 0.84 [0.78; 0.89]) of Acc were V₀ (partial r: 0.80 [0.72; 0.86]) and F₀ (0.57 [0.44; 0.68]); those of MSS (r² = 0.96 [0.94; 0.97]) were V₀ (0.96 [0.94; 0.97]) and P_max (0.73 [0.63; ?0.80]). High/Med have likely greater F₀ (Cohen’s d: +0.8 [0.0; 1.5]), V₀ (+0.6 [?0.1; 1.3]) and P_max (+0.9 [0.2; 1.7]) than Low/Med. High/Fast have an almost certainly faster V₀ (+2.1 [1.5; 2.7]) and a likely greater P_max (+0.6 [?0.1; 1.3]) than High/Med, with no clear differences in F₀ (?0.0 [?0.7; 0.6]). Speed may be a generic quality, but the mechanical horizontal determinants of Acc and MSS differ. While maximal speed training may improve both Acc and MSS, improving horizontal force production capability may be efficient to enhance sprinting performance over short distances.     

Cross-language activation of phonology in young bilingual readers

We investigated whether children who were learning to read simultaneously in English and French activate phonological representations from only the language in which they are reading or from both of their languages. Children in French Immersion programs in Grade 3 were asked to name aloud cognates, interlingual homographs, interlingual homophones, and matched control words. Half of the participants performed the task in English, their first oral language, and half performed the task in French. Control monolingual children in each language were also tested. In the French reading task, fewer errors were observed for cognates and interlingual homophones than for matched control words, whereas more errors were produced for interlingual homographs than matched controls. Only the inhibitory interlingual homograph effect was observed in the English reading task. These data provide evidence that phonological activation in bilinguals is not language selective. The locus of each of these effects in the bilingual word recognition system is discussed.     

A web information system for the management and the dissemination of Cultural Heritage data

Safeguarding and exploiting Cultural Heritage induce the production of numerous and heterogeneous data. The management of these data is an essential task for the use and the diffusion of the information gathered on the field. Previously, the data handling was a hand-made task done thanks to efficient and experienced methods. Until the growth of computer science, other methods have been carried out for the digital preservation and treatment of Cultural Heritage information. The development of computerized data management systems to store and make use of archaeological datasets is then a significant task nowadays. Especially for sites that have been excavated and worked without computerized means, it is now necessary to put all the data produced onto computer. This allows preservation of the information digitally (in addition with the paper documents) and offers new exploitation possibilities, like the immediate connection of different kinds of data for analyses, or the digital documentation of the site for its improvement. Geographical Information Systems have proved their potentialities in this scope, but they are not always adapted to the management of features at the scale of a particular archaeological site. Therefore this paper aims to present the development of a Virtual Research Environment dedicated to the exploitation of intra-site Cultural Heritage data. The Information System produced is based on open-source software modules dedicated to the Internet, so users can avoid being software driven and can register and consult data from different computers. The system gives the opportunity to do exploratory analyses of the data, especially at spatial and temporal levels. The system is compliant to every kind of Cultural Heritage site and allows management of diverse types of data. Some experimentation has been done on sites managed by the Service of the National Sites and Monuments of Luxembourg.     

Personal and Situational Factors Influencing Intrinsic Interest of Adolescent Girls in School Physical Education: a structural equation modelling analysis

This study assessed the influence of individual and contextual factors on adolescent girls’ interest in school physical education (PE). Specifically, girls (N = 700) were assessed on: (a), perceptions of their PE class climate, using the Perceived Motivational Climate Scale (PMCS, Cury et al., 1994; (b) dispositional achievement goal orientations, using the French version of the Perception of Success Questionnaire (POSQ, Durand et alM in press; and (c) the interest and competence subscales from the French version of the Intrinsic Motivation Inventory (IMI, Cury et al., 1994a). Structural equation modelling analysis, using LISREL VII, showed an excellent fit with the hypothesised model. Specifically, situational class climate was found to be more important than individual goals in influencing pupil interest in PE. However, perceived competence also influenced interest, as did a mastery goal orientation. Results are discussed in the context of theoretical propositions of goal perspectives theory and practical issues of enhancing adolescent girls’ interest in physical education.     

Effects of Collaborative and Individual Learning in a Blended Learning Environment

In courses using a virtual learning environment (VLE), some students like to work together, and some do not. If we give students the opportunity to choose either teamwork or individual study, how does this affect their marks and their appraisal and assessment of the course? This question has been investigated in the context of an English Literature course at the University of Utrecht. In this course, students work intensively with a VLE, and attend lectures: a blended learning environment. Previous research has shown that the pedagogical design used provides a powerful learning environment. This time, students had the choice of working on the course assignments in small teams (2–4 students), or individually. Both groups were compared based on their study results, and the answers to a questionnaire. Students valued the choice. Mainly those students with high marks for a previous course, which had a similar pedagogical design, preferred collaboration. Statistical analysis showed that collaboration resulted in significantly better marks.     

Perception of boys’ mother-son social interactions: Disruptive boys’ behaviors and involvement in learning tasks

This study focused on the relationship between social perception and children’s involvement in learning tasks. The interaction between disruptive boys’ (n=32) perception of the competence attributed to them by their mother, the mother’s behavior (verbal and physical intrusion) and the child’s involvement in learning tasks was observed in a laboratory setting. Boys were asked to solve easy and difficult tasks on a personnal computer under the supervision of their mother. Observations of mother-child interactions showed that disruptive boys with a negative perception of the competence attributed to them by their mother, were less involved in the difficult task than boys who had a positive perception. Mothers of the boys with a negative perception showed more verbal intrusions in the easy task and more physical intrusions in the difficult task than the mothers of boys with a positive perception. Mothers’ verbal intrusion, physical intrusion and boys’ involvement in the task discriminated 75% of the boys with a negative social perception. These results seem to indicate that disruptive boys do not constitute an homogeneous group and that a significant variation in their involvement in a learning task is related to their perception of the competence attributed to them by their mother.     

A tale of two logics: social reproduction and mobilisation in university access in Quebec, 1945–2000

The 2012 Quebec students’ protests against university tuition fees fostered a debate on access to higher education in Quebec, and specifically on the Quebec ‘educational lag’. Using census data, we show that degree-holding is the same among Quebec French-speaking and Ontario English-speaking populations. Using event history analysis, we show that, during the second half of the twentieth century, university access increased at a different rhythm in each province and, within each province, within socio-linguistic groups. Quebec current education policy should not focus on the ‘educational lag’, which past policies have helped make up for, but on inequality in university access.     

Triggered lightning in France and New Mexico

The possibility of triggering lightning by a rocket carrying a thin wire was demonstrated on a ship by M. M. Newman in 1965. Since 1973, this technique has been developed in France for operation above land. The same equipment was used successfully in New Mexico in 1981 and 1982. Triggered lightning is very attractive for many studies on lightning physics and for testing various kinds of equipment and protection devices. This explains the initiation of similar programmes in several other places.