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A novel microfluidic device enabling selective generation of droplets and encapsulation of targets is presented. Unlike conventional methods, the presented mechanism generates droplets with unique selectivity by utilizing a K-junction design. The K-junction is a modified version of the classic T-junction with an added leg that serves as the exit channel for waste. The dispersed phase fluid enters from one diagonal of the K and exits the other diagonal while the continuous phase travels in the straight leg of the K. The intersection forms an interface that allows the dispersed phase to be controllably injected through actuation of an elastomer membrane located above the inlet channel near the interface. We have characterized two critical components in controlling the droplet size-membrane actuation pressure and timing as well as identified the region of fluid in which the droplet will be formed. This scheme will have applications in fluid sampling processes and selective encapsulation of materials. Selective encapsulation of a single cell from the dispersed phase fluid is demonstrated as an example of functionality of this design. 相似文献
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Felix T. Leung Melinda M. Franettovich Smith Julie A. Hides 《Journal of sports sciences》2017,35(21):2088-2092
There is a high incidence of injuries in rugby union due to the physical nature of the game. In youth rugby union, there are large variations in injury rates reported. Our study investigated the rates of injuries in school-level rugby union players in Australia using the consensus statement for rugby union injuries. Injury surveillance was conducted on 480 rugby players from 1 school in Queensland, Australia. Injury data were collected using paper-based injury recording forms during the 8-week rugby season using a “medical-attention” injury definition. In total, 76 players sustained one or more injuries, with a total of 80 injuries recorded. The overall injury rate was 31.8 injuries/1000 match player hours (95% CI, 25.4–39.4). Concussion had an incidence rate of 6.0/1000 match player hours (95% CI, 3.5–9.6). The incidence of upper limb and lower limb injuries were 9.1 and 9.9/1000 match player hours, respectively (95% CI, 5.9–13.5 and 6.6–14.5). The older age divisions had higher injury rates and most injuries occurred while tackling or being tackled. The injury rates observed in this sample of Australian school rugby union players provides direction for future studies to enable informed decisions relating to development of injury prevention programmes at this level of rugby. 相似文献
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This research explored cultures of silence around child sexual abuse (CSA). On July 10, 2018, in response to multiple sexual abuse cases occurring in sport, sport news site Deadspin published a reader letter detailing CSA. This article prompted others to comment by sharing their accounts of CSA. Through qualitative analysis of 47 posts, we analyzed CSA victims’ lived experiences, with a focus on how cultural and social forces silenced them. Results indicated that silencing of CSA victims occurred through three overarching mechanisms: (a) patriarchal master narrative; (b) trauma-related shame; and (c) systemic power. The results illuminate the cultural and social factors that CSA victims experience and provide opportunities for parents, family members, and other stakeholders to better understand these constraints. In doing so, victims can be better supported, and needed discourse on CSA can occur more frequently to help identify solutions to this pervasive social problem. 相似文献
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A significant number of studies evidence girls' lack of participation in physical education. This study used feminist poststructuralism to examine the ways in which high school girls participated in or resisted physical education. Using qualitative research methods, researchers collected field notes, informal interviews, and formal interviews with the teacher and 15 female students. In contrast to previous studies, girls in this study enjoyed and valued physical activity. As active agents, they chose to participate in or resist specific physical activities through their negotiations of gender relations. Physical education classes emerged as a contested terrain in which girls supported the notion of equal opportunity in physical activity but perceived limits on their choices in physical education as compared to male peers. 相似文献
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Background: School physical education (PE) not only offers and promotes health-related physical activity (PA), but also encompasses the promotion and development of health-related well-being such as health-related quality of life (HRQOL). Furthermore, assessing PA and HRQOL have become major issues in pediatric public health and also serve as a major goal of Healthy people 2020. Grounded in the expectancy-value and achievement goal frameworks, the primary purpose of this study was to examine the relationships among the perceptions of motivational climate in PE, expectancy-value beliefs, HRQOL, and PA among elementary children. A secondary purpose was to test whether expectancy-value beliefs mediate the relationship between motivational climate and HRQOL as well as between motivational climate and PA (self-reported PA and pedometer-based PA, respectively).Methods: Participants were 336 elementary children recruited from three public schools in the southeastern USA (Mage?=?9.87; 179 girls, 157 boys). The majority of the participants (53.3%) were White students and the remainder (46.7%) including African-American (37.4%), Asian-American (1.5%), Hispanic-American (1.8%) and others (5.9%). Students completed a previously validated questionnaire assessing expectancy-related beliefs and task values toward PE. The 23-item pediatric QOL inventory generic core scale (PedsQLTM 4.0) was used to assess participants’ HRQOL. Children's PA levels were assessed by using a self-reported survey (Physical Activity Questionnaire for Older Children) and three-day pedometer counts (steps/min during PE).Analysis/Results: Correlational analyses showed that expectancy-related beliefs and task values were positively related to PA and HRQOL. Regression analyses indicated that both mastery and performance motivational climate had a positive effect on children's expectancy beliefs and task values. Mediational analyses were used to evaluate the potential mediational relationships among motivational climate (independent variables: mastery and performance climates), expectancy-value beliefs (mediator: expectancy-value beliefs), and HRQOL and PA (dependent variables: total HRQOL score, self-reported PA and steps/min), respectively.Conclusions: A mastery motivational climate together with high expectancy beliefs has a positive association with HRQOL, which in turn could produce health benefits in the future. Results suggest that a performance motivational climate could be associated with less activity (i.e. lower steps/min) even when students view PE as interesting, important, and useful. One important implication of the study is that by promoting mastery climates and expectancy-value beliefs in PE practitioners can encourage children to engage in PA both in and outside of school, and consequently may influence their quality of life. 相似文献
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Jianzhong Xu Ruiping Yuan Brian Xu Melinda Xu 《The Journal of educational research》2016,109(2):148-158
The authors examine the factors influencing mathematics homework interest for Chinese students and compare the findings with a recent study involving U.S. students. The findings from multilevel analyses revealed that some predictors for homework interest functioned similarly (e.g., affective attitude toward homework, learning-oriented reasons, monitoring motivation) across the two cultural samples, while some others did not (e.g., parent education, family homework help, and teacher feedback), suggesting that cultural differences influence students' interest in homework. In addition, this study bridges a gap in previous research on homework, by revealing that mathematics homework interest was positively related to mathematics self-concept. These findings were discussed relating to previous research in the field, and in the context of cultural values and societal influences. 相似文献
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Melinda R. Snodgrass Hedda Meadan Michaelene M. Ostrosky W. Catherine Cheung 《Early Childhood Education Journal》2017,45(6):855-862
Task analyses are useful when teaching children how to complete tasks by breaking the tasks into small steps, particularly when children struggle to learn a skill during typical classroom instruction. We describe how to create a task analysis by identifying the steps a child needs to independently perform the task, how to assess what steps a child is able to do without adult support, and then decide how to teach the steps the child still needs to learn. Using task analyses can be the key to helping a young child become more independent. 相似文献