Forward acceleration of the centre of mass during ski skating calculated from force and motion capture data

The purpose of this paper was to present and evaluate a methodology to determine the contribution of bilateral leg and pole thrusts to forward acceleration of the centre of mass (COM) of cross-country skiers from multi-dimensional ground reaction forces and motion capture data. Nine highly skilled cross-country (XC) skiers performed leg skating and V2-alternate skating (V2A) under constant environmental conditions on snow, while ground reaction forces measured from ski bindings and poles and 3D motion with high-speed cameras were captured. COM acceleration determined from 3D motion analyses served as a reference and was compared to the results of the proposed methodology. The obtained values did not differ during the leg skating push-off, and force–time curves showed high similarity, with similarity coefficients (SC) >0.90 in the push-off and gliding phases. In V2A, leg and pole thrusts were shown to contribute 35.1 and 65.9% to the acceleration of the body, respectively. COM acceleration derived from ground reaction forces alone without considering the COM position overestimated the acceleration compared to data from motion analyses, with a mean difference of 17% (P < 0.05) during leg push-off, although the shapes of force–time curves were similar (SC = 0.93). The proposed methodology was shown to be appropriate for determining the acceleration of XC skiers during leg skating push-off from multi-dimensional ground reaction forces and the COM position. It was demonstrated that both the COM position and ground reaction forces are needed to find the source of acceleration.     

Dynamics and control of the shape and size of a sitting drop-like meniscus, occurring in single-crystal growth

This paper concerns the following topics: dependence of shape and size of a static meniscus sitting like a drop on the controllable part of pressure difference across the free surface; stability of static menisci; procedure for creation of a stable static meniscus, appropriate for the growth of a rod with constant radius; temperature gradients and crystallization front displacement; equation for crystal dimension change rate; evolution of crystal radius and of the level of crystallization front; and control of cross-section during growth. This kind of problems appears in semiconductor single-crystal rod growth from a melt by edge-defined film-fed growth (EFG) technique. The novel case where the upper radius of the meniscus is larger than the shaper radius and the meniscus is sitting like a drop is analyzed. For some of the topics numerical illustrations are given. The obtained results can be useful in experiment planning and technology design of single-crystal rod growth by the EFG method. With this aim this study was undertaken.     

The influence of physical exercise on the relation between the phase of cardiac cycle and shooting accuracy in biathlon

This study examined the influence of physical exercise on the relation between shooting accuracy and the phase of the cardiac cycle in which the shot is fired. Thirteen experienced biathletes (8 females, mean age 17 years) fired from the standing position at rest and right after a submaximal exercise on a bicycle ergometer. Shooting accuracy and the timing of each shot relative to the R-waves of the electrocardiogram (ECG) were recorded. Best shots (with greatest accuracy) and worst shots (with lowest accuracy) were fired prevalently in different phases of the cardiac cycle. In the rest condition, best shots were fired less frequently from 200 to 300?ms and more frequently from 500 to 600?ms after the R-wave, compared to worst shots. In the exercise condition, best shots were fired less frequently from 100 to 200?ms after the R-wave and from 20% to 30% of the R-R interval, compared to worst shots. These findings support the hypothesis that shooting accuracy is influenced by the cardiac cycle phase due to the ballistocardiac recoil generated at each heartbeat. To achieve best results athletes could be trained (e.g. through biofeedback) to fire within a specific phase of the cardiac cycle.     

Cycling power output produced during flat and mountain stages in the Giro d'Italia: a case study

Until recently, the physiological demands of cycling competitions were mostly reflected by the measurement of heart rate and the indirect estimation of exercise intensity. The purpose of this case study was to illustrate the varying power output of a professional cyclist during flat and mountain stages of a Grand Tour (Giro d'Italia). Nine stage recordings of a cyclist of the 2005 Giro d'Italia were monitored using a mobile power measurement device (SRM Trainingssystem, Julich, Germany), which recorded direct power output and heart rate. Stages were categorized into flat (n = 5) and mountain stages (n = 4). Data were processed electronically, and the overall mean power in flat and mountain stages and maximal mean power for various durations were calculated. Mean power output was 132 W +/- 26 (2.0 W x kg(-1) +/- 0.4) for the flat and 235 W +/- 10 (3.5 W x kg(-1) +/- 0.1) for the mountain stages. Mountain stages showed higher maximal mean power (367 W) for longer durations (1800 s) than flat stages (239 W). Flat stages are characterized by a large variability of power output with short bursts of high power and long periods with reduced intensity of exercise, whereas mountain stages mostly require submaximal, constant power output over longer periods.     

Interdisciplinary and transdisciplinary research and practice: Balancing expectations of the ‘old’ academy with the future model of universities as ‘problem solvers’

Academics are increasingly required to balance the expectations of the ‘old’ academy with a future model of universities as interdisciplinary and transdisciplinary ‘problem solvers’. This paper highlights changing expectations of academics in producing alternative research outcomes in collaborative, practice‐based research. Through a series of workshops with 20 researchers, preferred research outcomes and tensions in achieving these outcomes were identified. The tensions identified are presented as three dichotomies comprising the tension between: (a) ‘I versus We’ ‐ individual versus team expectations & outcomes. (b) Disciplinary outcomes versus inter‐/transdisciplinary outcomes. (c) Learning versus research objectives for the students and academics involved. These tensions reflect the authors' experiences of working in three international sustainability projects, drawing on lessons learned from these projects, with recommendations for universities seeking to implement interdisciplinary and transdisciplinary doctoral and postdoctoral programmes. Recommendations include the need for formal and informal leadership models, strong communication skills, empathy and willingness to learn from each other. A need for more systemic changes within university administration to better reward and value the breadth and depth of collaborative work, while facilitating open learning cultures and practice‐oriented learning opportunities and curricula across faculties was also identified.     

Monitoring or avoiding health information--the relation to inner inclination and health status

Background: The way a person responds to health information, for instance by actively seeking it out or avoiding it, is an important part of overall coping with health issues. This study starts from the assumption that there are individual differences in information behaviour in charged contexts such as when faced with the stress and anxiety of compromised health. Objective: To shed light on mechanisms through which personal characteristics (locus of control) and world views (sense of coherence) influence health information interest and health information seeking in relation to health status. Method: The methods used in this study are quantitative. The material consists of data procured via a postal survey, which was posted to a representative sample group consisting of 2500 Finnish citizens aged 18–65 years. The statistical analysis consists of F‐tests for means, frequency analyses and cross tab‐analyses (chi‐square and Goodman–Kruskal gamma). Results: Persons with perceived health problems are comparatively more characterised by external locus of control and by lower motivation to act on health issues. Conclusion: More research is needed before these complex relationships are fully understood. However, the results of this study show that internal locus of control entails high interest in, and low avoidance of, health information.     

Exploring the unknown: the language use of German RE-students writing texts about God

Language does not only play an active part in all processes of comprehension, recognition and learning, it is also essential for specific religious learning processes. Religious experiences and traditions have their own characteristic linguistic forms, and religious education has come to realise the necessity for an appropriate sensibility in religious language. Yet while linguistic features of religion or tradition have been widely discussed and developed, the use of religious language with regard to the learning subjects remains a significant, if not unknown, variable. What do we actually know about the religious language of students? How do we systematically assess their linguistic competence? By presenting selected results regarding the God-talk of German secondary school students, this paper shows how empirical research based on a corpus linguistic approach can provide access to the use of religious language. As such, the paper first aims to initiate a paradigm shift from looking at the linguistic features of content to exploring the language use of learners. Second, it aims to present a research framework that offers possibilities for further comparable and comparative research well beyond the original German speaking context.     

Informal math coaching by instant messaging: Two case studies of how university students coach K-12 students

The aim of this study is to describe and explore how instant messaging (IM) can be used to support informal math coaching. We have studied two projects where university students use IM to coach K-12 students in mathematics. The coaches were interviewed with a focus on how informal coaching works by examining coaching challenges, how coaching can be organized, whether coaching should be anonymous or personal, which tools can be used and how informal math coaching supports learning. Research shows that generating and answering questions are important in the process of understanding and learning, which means that both the students and the coaches can learn math through this type of project. The coaches perceive informal math coaching as complementing online math forums. For students to learn effectively, the coaches need to be able to interpret the students' competence level in order to coach on a level that is within their development zone. It seems particularly challenging to coach at the right level when using IM and, therefore, it is important to establish a personal relationship with the students.     

Using Exploratory Bifactor Analysis to Understand the Latent Structure of Multidimensional Psychological Measures: An Example Featuring the WISC-V

Exploratory bifactor analysis (EBFA) represents a methodological advancement for implementing a bifactor model in exploratory factor analysis (EFA). However, little is known about how to properly employ the procedure. The current rotation criteria available for EBFA make it more likely to “get stuck” in local minima, contributing to possible group factor collapse, than more traditional EFA rotations. Thus, getting a proper solution is a more complex and involved process than typical EFA and may require a sensitivity analysis. This article examines EBFA through a sensitivity analysis and subsequent simulation of parameters thought to contribute to group factor collapse. Results support the use of sensitivity analysis, as the problematic variable was shown to greatly increase the likelihood of factor collapse. The hypothesis that estimation start values contribute to factor collapse was not supported. Accompanying R syntax for all analyses are provided to facilitate reproducibility.     

Modeling the Etiology of Individual Differences in Early Reading Development: Evidence for Strong Genetic Influences

We explored the etiology of individual differences in reading development from post-kindergarten to post–4th grade by analyzing data from 487 twin pairs tested in Colorado. Data from three reading measures and one spelling measure were fit to biometric latent growth curve models, allowing us to extend previous behavioral genetic studies of the etiology of early reading development at specific time points. We found primarily genetic influences on individual differences at post–1st grade for all measures. Genetic influences on variance in growth rates were also found, with evidence of small, nonsignificant, shared environmental influences for two measures. We discuss our results, including their implications for educational policy.