Rotating solenoidal perfect fluids of Petrov type D

We prove that aligned Petrov type D perfect fluids for which the vorticity vector is not orthogonal to the plane of repeated principal null directions and for which the magnetic part of the Weyl tensor with respect to the fluid velocity has vanishing divergence, are necessarily purely electric or locally rotationally symmetric. The LRS metrics are presented explicitly.Comment: 6 pages, no figure

Purely radiative perfect fluids

We study `purely radiative' (div E = div H = 0) and geodesic perfect fluids with non-constant pressure and show that the Bianchi class A perfect fluids can be uniquely characterized --modulo the class of purely electric and (pseudo-)spherically symmetric universes-- as those models for which the magnetic and electric part of the Weyl tensor and the shear are simultaneously diagonalizable. For the case of constant pressure the same conclusion holds provided one also assumes that the fluid is irrotational.Comment: 12 pages, minor grammatical change

From Youth Team to First Team: An Investigation into the Transition Experiences of Young Professional Athletes in Football

Using Wylleman and Lavallee (2004) and Stambulova (2003) models of transition as conceptual frameworks for the current study, we aimed to explore United Kingdom (UK) professional soccer players’ (N = 5) experiences going through a youth-to-senior career transition to first team level, and assess the immediate changes that occur during the move. Few studies have assessed this process, and no studies have focused on assessing the changes that may occur between pre and post transition. Data collection lasted 1 month with players interviewed twice, 2 weeks before, and 2 weeks after their transition to the first team. Data were abductively thematically content analyzed. Prior to transition, players reported high motivation to be successful, but also feeling anxious about the transition to senior sport. Post-transition, players felt more confident about their ability to succeed in senior sport and maintained high levels of motivation to succeed. Family, friends, coaches, and teammates provided emotional, technical, and tangible support to the players throughout the transition, but were also sources of stress for athletes moving to senior sport. These findings suggest ways to assist transitioning athletes, such as the use of buddy systems with senior players

Expanding perfect fluid generalizations of the C-metric

We reexamine Petrov type D gravitational fields generated by a perfect fluid with spatially homogeneous energy density and in which the flow lines form a timelike non-shearing and non-rotating congruence. It is shown that the anisotropic such spacetimes, which comprise the vacuum C-metric as a limit case, can have \emph{non-zero} expansion, contrary to the conclusion in the original investigation by Barnes (Gen. Rel. Grav. 4, 105 (1973)). This class consists of cosmological models with generically one and at most two Killing vectors. We construct their line element and discuss some important properties. The methods used in this investigation incite to deduce testable criteria regarding shearfree normality and staticity op Petrov type $D$ spacetimes in general, which we add in an appendix.Comment: 16 pages, extended and amended versio

Silent universes with a cosmological constant

We study non-degenerate (Petrov type I) silent universes in the presence of a non-vanishing cosmological constant L. In contrast to the L=0 case, for which the orthogonally spatially homogeneous Bianchi type I metrics most likely are the only admissible metrics, solutions are shown to exist when L is positive. The general solution is presented for the case where one of the eigenvalues of the expansion tensor is 0.Comment: 11 pages; several typos corrected which were still present in CGQ version; minor change

Developmental contexts and features of elite academy football players: Coach and player perspectives

Player profiling can reap many benefits; through reflective coach-athlete dialogue that produces a profile the athlete has a raised awareness of their own development, while the coach has an opportunity to understand the athlete's viewpoint. In this study, we explored how coaches and players perceived the development features of an elite academy footballer and the contexts in which these features are revealed, in order to develop a player profile to be used for mentoring players. Using a Delphi polling technique, coaches and players experienced a number of 'rounds' of expressing their opinions regarding player development contexts and features, ultimately reduced into a consensus. Players and coaches had differing priorities on the key contexts of player development. These contexts, when they reflect the consensus between players and coaches were heavily dominated by ability within the game and training. Personal, social, school, and lifestyle contexts featured less prominently. Although 'discipline' was frequently mentioned as an important player development feature, coaches and players disagreed on the importance of 'training'

A psycho-educational curriculum for sport career transition practitioners: Development and evaluation

Research question: This paper is an integration of three studies. Study 1 investigates sport career transition organisational intervention programmes for high performance athletes and training and development programmes for sport career transition practitioners in order to find a research gap with regard to sport career transition supporting services. A psycho-educational curriculum was developed for sport career transition practitioner in Study 2 to fill the research gap. In Study 3, the curriculum was examined to see if the curriculum contributed to enhancing practitioners’ confidence in key competences.  Research methods: A range of methods were applied to the studies including One Group Pre- and Post-test design, Case Study, Focus Group, Semi-Structured Interview, two-round Delphi-Method and Questionnaires. The data for Study 1 collected from 19 countries worldwide and total 16 participants based in seven different countries were invited to development and evaluation of the curriculum.  Results and Findings: A novel psycho-educational curriculum for sport career transition practitioner was developed and evaluated concerning four competences as a form of curriculum package. The findings revealed that the curriculum package increased the participants’ confidence in key competences concerning sport career transition.  Implications: The findings deepen the knowledge of sport career transition in the areas of organisational intervention programmes focusing on high performance athletes and sport career transition practitioners. These findings contribute to modifying the Conceptual Model of Adaptation to Career Transition (Lavallee, Park, & Taylor, 2014) by strengthening the organisational intervention perspective and applied work in respect of sporting organisation management strategie

Initial evidence for the criterion-related and structural validity of the long versions of the direct and meta-perspectives of the Coach-Athlete Relationship Questionnaire

This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2010 Taylor & Francis.The aim of the present study was to develop and initially validate a longer version of the direct (Jowett & Ntoumanis, 2004) and meta-perspectives (Jowett, 2009a, 2009b) of the Coach-Athlete Relationship Questionnaire (CART-Q). In Study 1, instruments (e.g. questionnaires, scales, and inventories) that have been used to assess relationship quality in the broader psychological literature were examined and items potentially relevant to the coach-athlete relationship were identified. The content validity of the identified items was then assessed using expert panels. A final questionnaire was subsequently prepared and administered to 693 participants (310 coaches and 383 athletes). Confirmatory factor analysis was employed to assess the multidimensional nature of the questionnaire based on the 3Cs (i.e. closeness, commitment, and complementarity) model of the coach-athlete relationship. The findings indicated that the direct and meta-perspective items of the long versions of the CART-Q approached an adequate data fit. Moreover, evidence for the internal consistency and criterion validity of the new instruments was also obtained. In Study 2, the newly developed measure was administered to an independent sample of 251 individuals (145 athletes and 106 coaches). Further statistical support was gained for the factorial validity and reliability of the longer version of the CART-Q

What do young athletes implicitly understand about psychological skills?

One reason sport psychologists teach psychological skills is to enhance performance in sport; but the value of psychological skills for young athletes is questionable because of the qualitative and quantitative differences between children and adults in their understanding of abstract concepts such as mental skills. To teach these skills effectively to young athletes, sport psychologists need to appreciate what young athletes implicitly understand about such skills because maturational (e.g., cognitive, social) and environmental (e.g., coaches) factors can influence the progressive development of children and youth. In the present qualitative study, we explored young athletes’ (aged 10–15 years) understanding of four basic psychological skills: goal setting, mental imagery, self-talk, and relaxation. Young athletes (n = 118: 75 males and 43 females) completed an open-ended questionnaire to report their understanding of these four basic psychological skills. Compared with the older youth athletes, the younger youth athletes were less able to explain the meaning of each psychological skill. Goal setting and mental imagery were better understood than self-talk and relaxation. Based on these findings, sport psychologists should consider adapting interventions and psychoeducational programs to match young athletes’ age and developmental level

The integration of single case designs in coaching contexts: A commentary for applied sport psychologists

From personal experiences of working with coaches toward the modification of behaviors and psychological constructs that include motivation, enjoyment, and self-confidence, this commentary highlights how the integration of single case designs can enhance the services of sport psychology practitioners. Interventions within golf, soccer, and tennis are outlined, targeting factors pertinent to the coaches, their players or team members, and the development of relationships with parents. Single case designs are posited as enabling the implementation of personal, evidence-based interventions that yield perceptible differences in cognitive, affective, and behavioral responses within athletic populations; factors that enhance and underpin the practitioner-coach relationship