Reliability and discriminative ability of a modified Wingate rowing test in 12- to 18-year-old rowers

We evaluated (1) the test-retest reliability of the Wingate test conducted on a rowing ergometer, and (2) the sensitivity of this test in determining the differences in performance attained by 12- to 18-year-old rowers. Altogether, 297 male rowers aged 12.0-18.9 years (mean?±?s: 14.8?±?1.7) completed a maximal 30-s test on a rowing ergometer, and 80 rowers representing all age groups were retested after 5-7 days. No change was evident in participants' performance in terms of mean power output (P?=?0.726; Cohen's d?=?0.04), maximal power output (P?=?0.567; Cohen's d?=?0.06), and minimum power output (P?=?0.318; Cohen's d?=?0.11) in the second test. The intra-class correlation coefficients were high (≥0.973) and coefficients of variation were low (≤7.3%). A series of analyses of variance were used to compare the performances among 12- to 18-year-old rowers, and age-related increases in performance were evident (P?相似文献   

Establishing a successful physical activity program to recruit and retain women

Increasingly, health organisations and governing bodies in developed countries are paying serious attention to the problem of adult inactivity. Many of the programs designed to increase levels of activity, particularly amongst target populations, such as women, have not been systematically assessed for their effectiveness in recruiting women and helping them maintain activity levels. The purpose of this study was to determine what attracted and sustained women to participate in physical activity programs. Responses from a survey to sport and recreation program providers identified 64 successful programs in the state of Victoria, Australia. Eight of these programs were purposively selected for case study analysis. Data was collected from a focus group with women participants from each of these eight programs. Six core themes emerged from inductive content analysis of the focus groups. The most frequent participant responses related to the social aspects of the exercise environment. Women in the focus groups valued instructor professionalism and instructors’ technical knowledge, however, it was their awareness and sensitivity that participants appreciated most. This exploratory study is important because it reflects the voices of women talking about what made physical activity programs successful for them. The study raises critical questions that should be examined systematically through large-scale survey research and field-based intervention studies, which in turn should stimulate program development to encourage women in physical activity.     

Search on surfaces: Exploring the potential of interactive tabletops for collaborative search tasks

Collaborative information seeking often takes place in co-located settings; such opportunities may be planned (business colleagues meeting in a conference room or students working together in a library) or spontaneous (family members gathered in their living room or friends meeting at a café). Surface computing technologies (i.e., interactive tabletops) hold great potential for enhancing collaborative information seeking activities. Such devices provide engaging direct manipulation interactions, facilitate awareness of collaborators’ activities, and afford spatial organization of content. However, current tabletop technologies also present several challenges that creators of collaborative information seeking system must account for in their designs. In this article, we explore the design space for collaborative search systems on interactive tabletops, discussing the benefits and challenges of creating search applications for these devices. We discuss how features of our tabletop search prototypes TeamSearch, FourBySix Search, Cambiera, and WeSearch, illustrate different aspects of this design space.     

Changes in children's peer interactions following a natural disaster: How predisaster bullying and victimization rates changed following Hurricane Katrina

Youth exposed to disasters experience stress and adjustment difficulties, which likely influence their interactions with peers. In this study, we examined changes in bullying and peer victimization in two cohorts of children. Youth from an area affected by Hurricane Katrina were assessed pre‐ and postdisaster (n = 96, mean [M] = 10.9 years old, 53% female), and a comparison group from a nearby area was assessed over the same time interval 1 year prior (n = 120, M = 10.2 years old, 52% female). Within the hurricane group, relations between symptoms of post‐traumatic stress disorder (PTSD) with bullying and victimization also were examined. Following the hurricane, the hurricane group reported increased relational and overt bullying relative to the nonhurricane group, and PTSD symptoms predicted increased victimization. Thus, school personnel should be vigilant and prepared to respond to increased bullying following disasters and for increased victimization in youth experiencing PTSD symptoms. © 2009 Wiley Periodicals, Inc.     

Arts engagement outside of school: Links with Year 10 to 12 students’ intrinsic motivation and self-efficacy in responding to art

This study draws on student engagement factors to examine the relationship between students’ non-school-based arts experiences on their intrinsic motivation and self-efficacy to participate in visual arts responding tasks. Visual arts responding in the curriculum includes learning about artists and artworks, decoding art and making critical judgements, and is important in building twenty-first century learning skills such as critical thinking and communication. A total of 266 Year 10 to 12 students from 18 schools in Western Australia (WA) participated in the quantitative research, which explored outside-school arts engagement as well as cognitive and psychological engagement factors in their current year of secondary schooling. The findings showed that while being an art consumer appears to impact on intrinsic motivation and self-efficacy, producing art as a hobby outside of school does not appear to do so. The research raised questions about links between practice and theory, and how to promote students’ engagement in responding.     

Truncation error analysis in computing of SEP and SEP floor for partially coherent receiver of MPSK signals over composite fading channels

In this paper, we analyze detection of multilevel phase-shift keying (MPSK) signals transmitted over a Gamma shadowed Nakagami-m fading channel. We derive novel analytical expression, in terms of Meijer’s G function, for Fourier coefficients of the probability density function of the received signal composite phase. Under the assumption of the imperfect reference signal extraction in the receiver, which is performed from the pilot signal, the analytical expression is derived for the symbol error probability (SEP) in the form of convergent series. The existence of the error floor is identified, and expression for its computation is provided. Mathematical proofs for convergence of Fourier series are provided for both SEP and SEP floor, and novel expressions of upper bounds for truncation errors are derived in terms of elementary mathematical functions. The convergence rate of the derived expressions is examined. Numerical results are confirmed independently by Monte-Carlo simulations.     

Food intake and appetite following school-based high-intensity interval training in 9–11-year-old children

Using a randomised cross-over design, free-living lunch intake and subjective appetite were examined in 10 children (9.8 ± 0.6 years) following high-intensity interval training (HIIT) versus a control sedentary (SED) period, within a school setting. The 22-min HIIT took place during a regular PE lesson and consisted of two rounds of 4 × 30 s sprints. Foods were offered at a regular school lunch immediately following HIIT and SED and were matched between conditions. All food was covertly weighed before and after the meal. Hunger, fullness and prospective consumption were reported immediately before and after HIIT/SED, using visual analogue scales. Heart rate was higher during HIIT than SED (159.3 ± 23.1 vs. 76.9 ± 2.2 bpm, P < 0.05). Lunch energy intake was not different (P = 0.52) following HIIT, compared to SED (2.06 ± 0.35 vs. 2.09 ± 0.29 MJ, respectively). There were no significant differences in macronutrient intake or subjective appetite (P > 0.05). Results suggest that HIIT can be implemented in a PE lesson immediately before lunch, without causing a compensatory increase in food consumption.