Comparing the pre- and post-impact ball and racquet kinematics of elite tennis players' first and second serves: a preliminary study

The aim of this study was to compare the pre- and post-impact three-dimensional kinematics of the ball and racquet during first and second serves performed by elite tennis players. Data were collected from four male and four female right-handed professional players during competition using two high-speed cameras (200 Hz). For each player, one first serve and one second serve from the 'deuce' or right service court that landed within the specified target area were analysed. To test for significant differences between the first and second serves, Wilcoxon tests (P < or = 0.05) were performed on selected parameters. The results indicate that the ball travelled forward and to the left during the flight phase of the toss in all but one trial. The average pre-impact ball forward location for the first serve was significantly more in front and had a higher associated forward ball velocity than the corresponding values for the second serve. On average, the decrease in post-impact ball speed from the first to the second serve was 24.1%. No significant differences between the first and second serves were found in the pre-impact racquet head speed and orientation, which was represented as a unit vector perpendicular to the racquet face. The major adjustments made by the players when going from the first to second serve were a decrease in pre-impact ball forward location (P < or = 0.01) and an increase in the pre-impact racquet vertical and lateral velocities (both P < or = 0.05). This implies that the players tossed the ball closer to the body and imparted topspin and sidespin on the ball by changing the racquet vertical and lateral velocities when going from the first to the second serve.     

Love,Loss and Magic: Connecting Author and Story1

The themes of love, loss and magic have been enduring themes in fairytales, myths, legends and fantasy within the genre of children's literature. These stories frequently depict young protagonists who have been ‘orphaned’ in some way—for example, through death, betrayal, absence, rejection or unexplained disappearance. In many of these narratives an important feature is the power of the story to grip and hold its readers through the intervention of magic in its most sinister and beneficent form as well as the love and loyalty of friends and creatures drawn from the world of fantasy. What is seldom examined is the way in which the author's own biography of loss and love both informs and provides a major impetus to the stories they have written. This article explores the way in which the themes of love, loss and magic interconnect with two phenomenally successful contemporary children's writers. Using selected extracts from the work of Philip Pullman and Michael Morpurgo, the article suggests a dynamic synergy with the authors and their stories.     

Physical activity patterns of ethnic children from low socio-economic environments within the UK

Many children fail to meet physical activity (PA) guidelines for health benefits. PA behaviours are complex and depend on numerous interrelated factors. The study aims to develop current understanding of how children from low Socio-economic environments within the UK use their surrounding built environments for PA by using advanced technology. The environment was assessed in 96 school children (7–9 years) using global positioning system (GPS) monitoring (Garmin Forerunner, 305). In a subsample of 46 children, the environment and PA were assessed using an integrated GPS and heart rate monitor. The percentage of time spent indoor, outdoor, in green and non-green environments along with time spent in moderate-to-vigorous PA (MVPA) in indoor and outdoor environments were assessed. A 2-by-2 repeated measures analysis of covariance, controlling for body mass index, BF%, assessed the environmental differences. The findings show that 42% of children from deprived wards of Coventry fail to meet PA guidelines, of which 43% was accumulated during school. Children engaged in more MVPA outdoor than indoor environments (P < 0.01) and a greater amount of time was spent in non-green environments (P < 0.01). Increased time outdoors was negatively associated with BF%. In conclusion, outdoor environments are important for health-enhancing PA and reducing fatness in deprived and ethnic children.     

Testing the specificity of environmental risk factors for developmental outcomes

Developmental theories often assume that specific environmental risks affect specific outcomes. Canonical Correlation Analysis was used to test whether 28 developmental outcomes (measured at 11–15 years) share the same early environmental risk factors (measured at 0–3 years), or whether specific outcomes are associated with specific risks. We used data from the UK Millennium Cohort Study (N = 10,376, 51% Female, 84% White) collected between 2001 and 2016. A single environment component was mostly sufficient for explaining cognition and parent-rated behavior outcomes. In contrast, adolescents’ alcohol and tobacco use were specifically associated with their parents’, and child-rated mental health was weakly associated with all risks. These findings suggest that with some exceptions, many different developmental outcomes share the same early environmental risk factors.     

Enabling integrated knowledge acquisition and management in health care teams

Basing treatment, policy and planning decisions on the best available research knowledge remains a central principle in modern health care around the world, yet many health professionals find acquiring and managing published research knowledge challenging. In this paper, we report on a Soft Systems Methodology-based collaborative action research initiative with a specialist mental health service from the United Kingdom's National Health Service. Our objective was to design and implement improvements to their knowledge acquisition and management activities in order to facilitate sustained and effective evidence-based practices. We report on both the factors found to impede effective research knowledge acquisition and management and the development of more integrated knowledge management processes designed to improve the situation.     

A comparison of the perceptions of Love, Anger, and Guilt in Portugal and the United States and implications for counseling

This study compared the ways that graduate and undergraduate counseling and psychology students from Portugal and the United States evaluated the feelings of Love, Anger and Guilt. Utilizing a semantic differential, a multivariate analysis of variance was employed in which the independent variables were Country and Gender and the dependent variables were the evaluative and potency scales of Love, Anger and Guilt. There was no significant main effect for gender and there was no significant interaction effect for gender by country. There was a significant main effect for country. It was found that students from the United States evaluated Anger more positively than the Portuguese students and that the Portuguese students evaluated Guilt more positively than the United States students. These findings have implications that are relevant to the counseling process.     

Dealing with ‘fragile identities’: resistance and refiguring in women mathematics students

Many learners may be successful in mathematics but nevertheless see themselves as existing only on the margins of the practice, or as lacking stability in it – in this sense, they have what can be called a fragile identity. Although this kind of relationship with mathematics is not limited to girls and women, they do appear to express such fragile identities more often or more readily. Drawing on qualitative and quantitative data from undergraduates in three English universities, this paper presents an analysis of the way in which university mathematics is differentially experienced by men and women, and of the part this may play in women’s ongoing narratives of self as mathematicians. It is suggested that some women resist traditional positionings in the mathematics world, drawing on local resources which enable a sense of agency as successful students and a refiguring of their relationships with mathematics.     

Threshold values and Boolean retrieval systems

Several papers have appeared that have analyzed recent developments in the problem of processing, in a document retrieval system, queries expressed as Boolean expressions. The purpose of this paper is to continue that analysis. We shall show that the concept of threshold values resolves the problems inherent with relevance weights. Moreover, we shall explore possible evaluation mechanisms for retrieval of documents, based on fuzzy-set-theoretic considerations.