Between-Day Reliability and Usefulness of a Fitness Testing Battery in Youth Sport Athletes: Reference Data for Practitioners

This study aimed to evaluate the between-day reliability and usefulness of a fitness testing battery in a group of youth sport athletes. Fifty-nine youth sport athletes (age = 17.3 ± 0.7 years) undertook a fitness testing battery including the isometric mid-thigh pull, counter-movement jump, 5–40 m sprint splits, and the 5–0-5 change of direction test on two occasions separated by 7 days. Usefulness was assessed by comparing the reliability (typical error) to the smallest worthwhile change. The typical error was 5.5% for isometric mid-thigh pull and 3.8% for counter-movement jump. The typical error values were 2.7, 2.5, 2.2, 2.2, and 1.8% for the 5, 10, 20, 30, and 40 m sprint splits, and 4.1% (left) and 5.4% (right) for the 5–0-5 tests. The smallest worthwhile change ranged from 1.1 to 6.1%. All tests were identified as having “good” or “acceptable” reliability. The isometric mid-thigh pull and counter-movement jump had “good” usefulness, all other tests had “marginal” usefulness.     

Effects of acute exercise,dehydration and rehydration on cognitive function in well-trained athletes

This study investigated the effects of aerobic exercise, fluid loss and rehydration on cognitive performance in well-trained athletes. Ten endurance-trained males (25 ± 5 years; 175 ± 5 cm; 70.35 ± 5.46 kg; VO_2max, 62.95 ± 7.20 ml · kg.min^?1) lost ~2.5 ± 0.6% body mass via continuous cycling exercise at ~65% peak sustainable power output (60 min duration) before consuming different beverages (Water = W1 and W2, Sustagen Sport = SS, Powerade = PD) and food ad libitum on four separate occasions. Cognitive function using a four-choice reaction time task (CRT), body mass, fluid consumption volumes, urine samples and subjective ratings (alertness, concentration, energy) were obtained before and after exercise, and hourly during recovery (for 4 h). CRT latency was significantly reduced immediately after exercise compared to pre-exercise measures for all trials (W1 = ?16 ± 18 ms, W2 = ?22 ± 21 ms, PD = ?22 ± 22 ms, SS = ?19 ± 26 ms). However, this effect was short-lived with subsequent measures not different from pre-exercise values. No difference in CRT accuracy was observed at any time across all trials. Subjective ratings were not different at any time across all trials. Aerobic exercise, hypohydration or an interaction between these two may provide a small cognitive performance benefit. However, these effects are temporary and confined to the immediate post-exercise period.     

Silicon startup schools: technocracy,algorithmic imaginaries and venture philanthropy in corporate education reform

Technology companies are investing billions of dollars in educational technology, but also creating their own alternative schools. This article traces the emergence of four prototypical ‘silicon startup schools’ as exemplars of a technocratic mode of corporatized education reform: IBM’s P-TECH, part of its Smarter Cities program; AltSchool, a chain of schools based on ‘makerspaces’ established by a former Google executive; Kahn Lab School, a new ‘experimental’ school launched by the founder of the online Kahn Academy; and XQ Super School Project, a ‘crowdsourcing’ project to redesign American high schools funded philanthropically by the wife of Steve Jobs of Apple. Startup schools are analysed as prototype educational institutions that originate in the culture, discourse and ideals of Silicon Valley venture capital and startup culture, and that are intended to relocate its practices to the whole social, technical, political and economic infrastructure of schooling. These new schools are being designed as scalable technical platforms; funded by commercial ‘venture philanthropy’ sources; and staffed and managed by executives and engineers from some of Silicon Valley’s most successful startups and web companies. Together, they constitute a powerful shared ‘algorithmic imaginary’ that seeks to ‘disrupt’ public schooling through the technocratic expertise of Silicon Valley venture philanthropists.     

Technology and Teacher–Student Interactions: A Review of Empirical Research

As technology becomes ubiquitous in education, it is critical to understand the ways in which technology influences interactions between teachers and their students. The overarching research question that guided this systematic review was: What does research tell us about how technology influences interactions between teachers and students in K–12 settings? This review examined studies published in peer-reviewed journals between 2005 and 2016. Findings indicated that studies examined two types of teacher–student interactions that technology influenced: (a) face-to-face interactions in traditional classrooms, and (b) online interactions in traditional and virtual classrooms. Technology promoted collaboration between teachers and students during learning activities, and teachers who used technology leveraged it to maximize their uses of strategies aimed at facilitating learning and promoting students' exploration of content. (Keywords: teacher–student interaction, educational technology, technology, integration)     

Users can change their web search tactics: Design guidelines for categorized overviews

Categorized overviews of web search results are a promising way to support user exploration, understanding, and discovery. These search interfaces combine a metadata-based overview with the list of search results to enable a rich form of interaction. A study of 24 sophisticated users carrying out complex tasks suggests how searchers may adapt their search tactics when using categorized overviews. This mixed methods study evaluated categorized overviews of web search results organized into thematic, geographic, and government categories. Participants conducted four exploratory searches during a 2-hour session to generate ideas for newspaper articles about specified topics such as “human smuggling.” Results showed that subjects explored deeper while feeling more organized, and that the categorized overview helped subjects better assess their results, although no significant differences were detected in the quality of the article ideas. A qualitative analysis of searcher comments identified seven tactics that participants reported adopting when using categorized overviews. This paper concludes by proposing a set of guidelines for the design of exploratory search interfaces. An understanding of the impact of categorized overviews on search tactics will be useful to web search researchers, search interface designers, information architects and web developers.     

静态法研究D290大孔阴离子交换树脂吸附Se(Ⅳ)的性能

本文详细考察了D290大孔阴离子交换树脂对Se（Ⅳ）的静态吸附性能,确定了最佳吸附酸度为6mol／LHCl溶液,测定了静态变换容量为134．2mg／g·R,D290树脂与Se（Ⅳ）的配位比为2：1。     

The Role of Executive Functions in Socioeconomic Attainment Gaps: Results From a Randomized Controlled Trial

The socioeconomic attainment gap in mathematics starts early and increases over time. This study aimed to examine why this gap exists. Four-year-olds from diverse backgrounds were randomly allocated to a brief intervention designed to improve executive functions (N = 87) or to an active control group (N = 88). The study was preregistered and followed CONSORT guidelines. Executive functions and mathematical skills were measured at baseline, 1 week, 3 months, 6 months, and 1 year posttraining. Executive functions mediated the relation between socioeconomic status and mathematical skills. Children improved over training, but this did not transfer to untrained executive functions or mathematics. Executive functions may explain socioeconomic attainment gaps, but cognitive training directly targeting executive functions is not an effective way to narrow this gap.