Growth and characterization of micro-crystalline silicon-germanium and silicon-carbon films

http://www.worldcat.org/oclc/3930814

Master of Science

thesisThis study was initiated after observing a high incidence of cervical ribs in stillborn fetuses referred for autopsy at our institution. The study establishes the prevalence of cervical ribs in this referral population and describes related associations. Radiologic data were reviewed from 389 stillborn and 171 liveborn autopsies performed at Primary Children's Medical Center from 2006 to 2011. Cervical ribs were identified in 49.1% of stillborn fetuses and 22.8% of liveborn infants at the time of autopsy. There was a statistically significant high association of cervical ribs in patients with aneuploidy. Karyotypes were available on 186 of the stillborn cases (47%). Of the patients with chromosome abnormality, 24 of 32 (75%) had cervical ribs. Our findings support the hypothesis that cervical ribs, a posterior homeotic transformation of the cervical-thoracic border, represent disadvantageous development during early stages of blastogenesis. This same region and patterning of the anterior to posterior skeletal axis has been conserved throughout evolution in almost all mammals

Playing by the rules: A developmentally appropriate introduction to rugby union

The current study examined the effect of rules changes on game behaviours and opinions of under-nine rugby union players. Eighty-nine games were filmed in five counties in England; two governed by the then current rules and three governed by new pilot rules. The pilot rules were designed to create a less structured game; reducing numbers on the pitch and limiting set pieces and specialised skills. Games played under the pilot rules had 25% more ball-in-play time; 55% more runs with the ball; more than twice as many successful passes; and nearly twice as many tries scored (ps<.001). 272 players participated in a survey. Irrespective of the rules, players identified that passing, running and tackling were key activities, while having fun and playing with friends were their main reasons for playing rugby. The results suggest that the pilot rules create a competitive game that closely matches child-led informal activities.This research was funded by a CASE studentship from the ESRC’s Capacity Building Cluster in Sport, Leisure and Tourism, based at the University of Exeter (RES-187-24-0002), in partnership with the Rugby Football Union. The authors would like to thank all the clubs and players who took part in this research and to Gary Townsend (RFU) for facilitating the process. We would also like to thank Kris James for his assistance in performance analysis of matches

Integrating Positive Youth Development within Coach Education for Youth Sport Coaches

info:eu-repo/semantics/publishedVersio

A season-long examination of the intervention tone of coach–athlete interactions and athlete development in youth sport

Objectives: Coaches are a primary influence on athletes' development in youth sport (Horn, 2008).However, the intervention tone of coaches' behaviour has not been directly observed. The purpose of this study was to examine associations between the intervention tone exhibited by youth sport coaches and athletes' individual developmental trajectories over the course of a season. Design: Short-term longitudinal study with behavioural observation. Method: Fifty-five athletes and their coaches from five youth volleyball teams were observed at three time points, and the intervention tone of interactive behaviour was systematically coded and organized by coach-athlete dyad. Athletes completed measures of the 4C's of athlete development (competence, confidence, connection, character) at each time point, which were used to create individualized developmental trajectories. Person-centred analyses were used to examine associations between athletes' developmental trajectories and their unique interactive experiences with their coach. Results: Cluster analysis revealed the presence of three distinct clusters based on athletes' develop-mental trajectories: 1) high and increasing, 2) low and decreasing, and 3) moderate and maintaining, with athletes from each team distributed across clusters. Analysis of dyadic interaction profiles revealed significant differences in interactive behaviour between clusters. Conclusions: Results suggest that differences in coach-athlete interactive experiences are associated with different developmental trajectories over the course of a season, even for athletes working with the same coach, highlighting the individualized nature of coaches' influence on young athletes. Practical implications for coaches include a critical awareness of their unique interactive relationship with each athlete independently, as well as the importance of fostering these relationships with regard to young people as more than just athletes

An Exploratory Examination of Interpersonal Interactions between Peers in Informal Sport Play Contexts

Athlete-driven informal sport play represents an important context for athlete development. However, in contrast to coach-driven organized sport, little is known about the interpersonal processes driving development in this context. The present study was an exploratory descriptive analysis of the interactive peer behaviors occurring in an informal sport play setting and their relationship to athlete psychological characteristics. Thirty young athletes (<25 years old, Mage = 19.84) participating in informal mixed-age volleyball, soccer, and basketball sessions at a community recreation center were observed and their interactive behavior coded. Participants also completed questionnaire measures of psychological characteristics (competence, confidence, character). Descriptive analyses examined the interaction patterns of young athletes in these contexts. Multiple regression analyses were then conducted to examine the relationships between peer interactive behavior and athlete psychological characteristics. Results point to the social nature of participation in informal sport play contexts and the critical relationship between athlete competence and peer interaction tendencies. This study presents an initial exploration of peer interactive behavior in informal, mixed-age sport play contexts, but continued future research is needed to better understand the developmental processes and implications of participation in these important contexts

Effects of low earth orbit on the optical performance of multi-layer enhanced high reflectance mirrors

Two mirror designs developed for space applications were flown along with a standard mid-infrared design on the leading and trailing edges of the Long Duration Exposure Facility (LDEF). Preliminary observations of induced changes in optical performance of ZnS-coated mirrors and impact-related microstructural and microchemical effects are described in the proceedings of the First LDEF Post-Retrieval Symposium. In this paper, effects of the induced environment and meteoroid/debris impacts on mirror performance are described in more detail. Also, an analysis of reflectance spectra using the results of Auger and secondary ion mass spectroscopy (SIMS) profiling measurements are used to identify an optical-degradation mechanism for the ZnS-coated mirrors. Structural damage associated with a high-velocity impact on a (Si/Al2O3)-coated mirror was imaged optically and with scanning electron and atomic force microscopy (SEM and AFM). Scanning Auger and SIMS analysis provided chemical mapping of selected impact sites. The impact data suggest design and fabrication modifications for obtaining improved mechanical performance using a design variation identified in preflight laboratory simulations. Auger surface profile and SIMS imaging data verified the conclusion that secondary impacts are the source of contamination associated with the dendrites grown on the leading-edge ZnS-coated test samples. It was also found that dendrites can be grown in the laboratory by irradiating contaminated sites on a trailing-edge ZnS-coated sample with a rastered electron beam. These results suggest a mechanism for dendrite growth

Youth Sport and COVID-19: Contextual, Methodological, and Practical Considerations

One of the growing concerns among youth sport stakeholders is how the COVID-19 pandemic will shape youth sport development. Given the novelty and rapidly changing nature of these events, the impacts on development are not yet clear. Thus, to gain a deeper understanding of the impact of this crisis, it is crucial for researchers and practitioners to examine the effects on youth development at different timescales. Although we are seeing immediate changes in the activities, social dynamics, and settings that are influencing youth's real-time experiences, questions remain regarding its influence on short-, and long-term developmental outcomes (Kelly et al., 2020). Moving forward, we will need to be cognizant of how this watershed moment will shape youth sport development for months and years to come. As such, this opinion article will focus on exploring potential contextual, methodological, and practical considerations that may be relevant as we navigate through these uncertain times. Further, we hope to encourage researchers and practitioners to embrace this as an opportunity to critically reflect and evaluate the existing practice of youth sport