First Snow Aubade

Pages 61-6

Picking up the pace:the development of pacing behaviour during adolescence

How individuals distribute their effort during exercise (i.e. pacing) plays a key role in facilitating sports performance and exercise participation. In this thesis, we studied the development of pacing behaviour during adolescence. In a series of observational studies, the pacing behaviour of over 15,000 athletes (runners, swimmers and short-track speed skaters), aged 12-24, was studied using lap times recorded during competition. These studies demonstrated that in general the development of pacing behaviour 1) starts in late childhood, is most prominent during adolescence and becomes more gradual towards adulthood, 2) peaks at an earlier age in girls compared to boys, and 3) results in a distribution of effort that better fits the task characteristics (task duration) and the environment (presence of competitors). In a series of laboratory experiments, the various aspects of pacing were compared between groups of adolescents and adults performing cycling time trials. These studies revealed that the following capabilities develop during adolescence: 1) estimating the amount of effort required to compete an exercise task (e.g. estimating the time needed to complete a trial) 2) self-monitoring and adapting one’s effort expenditure during exercise (e.g. cycling at a set goal speed), and 3) using past experiences to inform one’s pacing strategy. Given that these capabilities are still developing during adolescence, children and young adolescents have the tendency to base their effort expenditure on signals from the social environment (e.g. by watching their competitors). The findings from this thesis offer a theoretical basis for the informed design of interventions and practical tools aimed at supporting the distribution of effort during exercise. These tools could be used not only to optimize the performance of athletes, but also to enable children and adolescents to enjoy engaging in physical activity and promote a healthy lifestyle

Characterizing receptive vocabulary knowledge in minimally verbal children with autism spectrum disorder

Background: Delayed or impaired language skills are common characteristics of children with autism spectrum disorder (ASD). Currently, there is little research examining the receptive language profile in children with ASD, and even less is known about children with ASD who are minimally verbal. The current study aimed to characterize the receptive vocabulary profile of minimally verbal children with ASD and to examine whether this profile differs from their typically developing peers. Methods: Participants included 31 minimally verbal children with ASD, aged 60-118 months, who were reported to produce between 0-10 words, 124 typical developing toddlers, aged 9-14 months, who were matched on expressive vocabulary, and 124 typical developing toddlers, aged 8-18 months, who were matched on receptive vocabulary. Semantic and syntactic features of words that the children understood was examined using word-level responses from the MacArthur-Bates Communicative Development Inventory (Fenson et al. 2007). Results: Minimally verbal children with ASD understood a greater proportion of verbs compared to both typically developing groups. In terms of semantic categories, multiple differences were found between the minimally verbal ASD group and the typically developing expressive vocabulary-matched group. Interestingly, when compared to the receptive vocabulary-matched group, only one difference was found. Conclusions: Minimally verbal children with ASD displayed a similar receptive vocabulary profile to typically developing toddlers who were matched on receptive vocabulary abilities despite large differences in expressive vocabulary knowledge, chronological age, and mental age. These findings suggest new insight for future research using receptive-vocabulary matched groups as a point of comparison. Additionally, future studies should examine early verb learning and processing in minimally verbal children with ASD

Local Factors Determining Spatially Heterogeneous Channel Migration in a Low-Energy Stream

Since the 1990s, nature and water management policies have attempted to re-create natural rivers systems by mimicking curvy meandering planforms, based on the assumption that meandering is the natural channel-forming process. However, in low-energy river systems, the extent to which meandering plays a natural role is often minimal. This study aims to quantify contemporary lateral migration in the low-energy irregular sinuous lowland river system of the Drentsche Aa, The Netherlands, and to determine the factors influencing lateral channel migration in a heterogeneous valley fill. Although the river is classified as laterally immobile based on an empirical stability diagram, field observations prove that erosion and deposition are currently occurring. By analyzing historical and present-day maps, it was shown that lateral migration was highly spatially variable for the period 1924-2005. Sinuosity and valley gradient are not correlated to lateral migration rates, suggesting they are not a measure of lateral migration in the case study area, which is in line with the literature. Based on geomorphological and soil map analyses, it was shown that lateral migration rates are significantly higher in valley fills of aeolian sands than in clastic alluvial deposits, which on their turn are significantly higher than in peaty environments. Therefore, local conditions appear to be dominant over other factors such as stream power and bed grain size. These findings are important for river rehabilitation of low-energy rivers, because it shows that local valley fill conditions can greatly influence active lateral migration in the river

Mindfulness as substitute for transformational leadership

Purpose Transformational leaders spark the intrinsic motivation of employees, thereby stimulating their extra-role performance. However, not all employees are lucky enough to have a transformational leader. The purpose of this paper is to investigate to what extent mindfulness can function as a substitute for transformational leadership. By being attentive to and aware of what is taking place in the present, mindfulness provides employees with a source of intrinsic motivation that lies within the person, thereby possibly making employees less dependent on transformational leadership. Design/methodology/approach An online survey was used to collect data of 382 employees working in diverse sectors in the Netherlands. Findings Moderated mediation analyses indicated that mindfulness partly compensates for a low levels of transformational leadership in fostering intrinsic motivation and in turn extra-role performance, thereby providing evidence for the substitutes for leadership theory. Moreover, the findings extend previous research on the contribution of mindfulness to in-role performance by showing its additional value for intrinsic motivation and extra-role performance. Research limitations/implications Despite the use of validated measures and the presence of an interaction effect, common-source bias cannot be out ruled completely. Practical implications - Since mindfulness can be developed, the results suggest a training intervention to make employees less dependent on their leaders for their motivation. Originality/value This paper is the first to show that mindful people are more resilient against the absence of transformational leadership. Given the frequent changes in management layers in organizations, knowledge about resources for individual resilience and self-management is sorely needed