The relationship between peak height velocity and physical performance in youth soccer players

Longitudinal changes in height, weight and physical performance were studied in 33 Flemish male youth soccer players from the Ghent Youth Soccer Project. The players' ages at the start of the study ranged from 10.4 to 13.7 years, with a mean age of 12.2 +/- 0.7 years. Longitudinal changes were studied over a 5 year period. Peak height velocity and peak weight velocity were determined using non-smoothed polynomials. The estimations of peak height velocity, peak weight velocity and age at peak height velocity were 9.7 +/- 1.5 cm x year-1, 8.4 +/- 3.0 kg x year-1 and 13.8 +/- 0.8 years, respectively. Peak weight velocity occurred, on average, at the same age as peak height velocity. Balance, speed of limb movement, trunk strength, upper-body muscular endurance, explosive strength, running speed and agility, cardiorespiratory endurance and anaerobic capacity showed peak development at peak height velocity. A plateau in the velocity curves was observed after peak height velocity for upper-body muscular endurance, explosive strength and running speed. Flexibility exhibited peak development during the tear after peak height velocity. Trainers and coaches should be aware of the individual characteristics of the adolescent growth spurt and the training load should also be individualized at this time.     

Three-axis platform simulation: Bond graph and Lagrangian approach

A bond graph model is derived for the geometric constraints of a three-axis flight table. Gimbal dynamics are easily added even in asymmetrical and unbalanced cases. A method is introduced to make the local dependent inertias computable. The bond graph compares favourably to the Lagrangian approach as to modelling effort and accessibility of intermediate variables as well as having computational advantages.     

The Interplay of Psychology and Mathematics Education: From the Attraction of Psychology to the Discovery of the Social

It is a rather safe statement to claim that the social dimensions of the scientific process are accepted in a fair share of studies in the philosophy of science. It is a somewhat safe statement to claim that the social dimensions are now seen as an essential element in the understanding of what human cognition is and how it functions. But it would be a rather unsafe statement to claim that the social is fully accepted in the philosophy of mathematics. And we are not quite sure what kind of statement it is to claim that the social dimensions in theories of mathematics education are becoming more prominent, compared to the psychological dimensions. In our contribution we will focus, after a brief presentation of the above claims, on this particular domain to understand the successes and failures of the development of theories of mathematics education that focus on the social and not primarily on the psychological.     

The challenge to make schools safe: Preparing education personnel to curb student aggression and violence

Abstract

The incidence of aggression and violence in schools is approaching epidemic proportions. Unfortunately, few teacher education programs offer coursework designed to prepare school personnel to face the mounting challenge of student aggression. Drawing upon the accumulated literature, changes are discussed in the content of teacher education programs that would prepare teachers to effectively address student violence. Assertions are made that colleges of education must assume leadership roles in redefining professional boundaries to prepare all school personnel to combat student aggression. Lastly, arguments are presented for strengthening university and public school collaboration to promote programs designed to curb the rising tide of student aggression and violence.     

Application of the Levenshtein Distance Metric for the Construction of Longitudinal Data Files

The analysis of longitudinal data in education is becoming more prevalent given the nature of testing systems constructed for No Child Left Behind Act (NCLB). However, constructing the longitudinal data files remains a significant challenge. Students move into new schools, but in many cases the unique identifiers (ID) that should remain constant for each student change. As a result, different students frequently share the same ID, and merging records for an ID that is erroneously assigned to different students clearly becomes problematic. In small data sets, quality assurance of the merge can proceed through human reviews of the data to ensure all merged records are properly joined. However, in data sets with hundreds of thousands of cases, quality assurance via human review is impossible. While the record linkage literature has many applications in other disciplines, the educational measurement literature lacks details of formal protocols that can be used for quality assurance procedures for longitudinal data files. This article presents an empirical quality assurance procedure that may be used to verify the integrity of the merges performed for longitudinal analysis. We also discuss possible extensions that would permit merges to occur even when unique identifiers are not available.     

PROSPECTIVE MEMORY TRAINING IN OLDER ADULTS

This study evaluates the results of a training program for prospective remembering. The goal of the training was to improve prospective memory by associating cues from the retrieval situation with the to be remembered information. The training group consisted of 20 participants, aged between 45 and 81 years. The effects of strategy training were compared with those of an educational training group (N = 23 , age range 45-84) directed at reducing worries about forgetfulness, and a retest control group (N = 22 , age range 46-74). The educational training and retest control groups did not differ in demographic characteristics and test performance and were combined into one control group. Subjective evaluations revealed that subjects were very satisfied with the effects of training. This also was true for subjects in the educational training condition. The objective effects of training were evaluated with a telephone task which had to be performed in the daily life situation, and a prospective categorization task performed in the laboratory. Despite the low reliabilities of the prospective tasks, a significant but small effect of training compared to the combined control group was found on the sum score of prospective tests. The training effect was not related to age or pretraining performance level. At the three months follow-up, however, performance of the control group had increased to the level of the trained group. As expected, training effects did not generalize to other memory measures (assessed with tests for remembering names) or control measures (assessed with visuo-motor reaction time tests).     

The validity and reliability of focus groups as a research method in adult education

The article examines the theory and practice of focus groups in adult education research. Three theoretical positions are described: radical hermeneutic, moderate interpretative and pragmatic realistic position trying to bridge the gap with positivist research. This last position has been chosen as the departure point for a further analysis of the focus group elements, which relate to validity and reliability. The research examines four European research projects in the field of adult education. The most important and surprising data are presented with reference to both socio-psychological and technical problems in the use of this method. The results highlight the importance and dynamics of all the elements discussed.     

Making biodiversity meaningful through environmental education

Biodiversity is an emerging theme in science, society and, more recently, education. There is no one single definition of biodiversity that is adequate in all situations. Both the knowledge base and the value base of biodiversity are variable and questionable. Because of these characteristics, biodiversity makes for an interesting vehicle for linking science and society, and the investigation of the normative underpinnings of 'science-in-the making'. Based on a 3-year study, this paper explores the crossroads between science education and environmental education and presents a framework for tapping the environmental education potential of biodiversity. Outlined are a number stepping stones for making biodiversity meaningful to learners. It is argued that, from the perspective of environmental education, the illdefined nature of biodiversity is a useful feature. Biodiversity is renewing the discourse on nature conservation issues by bringing together different groups in society that are searching for a common language to discuss nature conservation issues in relation to sustainability issues. The resulting debate allows the socio-scientific dispute character of 'science-in-the-making' to surface. Participation in such a dispute is an excellent opportunity to learn about a highly relevant, controversial, emotionally charged and debatable topic at the crossroads of science, technology and society     

The effect of submaximal exercise on recovery hemodynamics and thermoregulation in men and women

Five women and 5 men were studied to examine the effects of submaximal exercise on thermoregulatory and hemodynamic variables during recovery in two environments: (a) control (C), 22 degrees C, 33% rh; and (b) hot humid (H), 32 degrees C. The participants exercised on a cycle ergometer at 60% of peak oxygen consumption for 35 min prior to 90 min of seated recovery. Sessions were identical, except for environment. Variables evaluated (p < .05) were: core temperature (TR), mean skin temperature (Ts), sweat rate (SR), heart rate (HR), stroke index (SI), cardiac index (CI), forearm blood flow (FBF), systolic blood pressure (SBP), and diastolic blood pressure (DBP). Men and women exhibited similar patterns of TR, Ts, and SR in both environments. Ts and SR (collapsed means for gender) were higher in the H than in the C. DBP was higher in men than in women throughout recovery in both environments. With combined means for gender, HR was higher in the H than in the C. CI, SI, FBF, and SBP were similar in both environments and returned to baseline within 15 min into recovery. These data suggest that heat dissipation during extended recovery was accomplished with similar contributions of cutaneous vasodilation and sweating in M and F. Furthermore, the moderate exercise level did not influence hemodynamics beyond 15 min of recovery in either environment.