Participation-related relative age effects in Masters swimming: a 6-year retrospective longitudinal analysis

Medic and colleagues (Medic, Starkes, & Young, 2007) found that relatively younger cohorts of Masters athletes had higher participation rates and achieved higher performances compared with a relatively older cohort. Considering that Medic and colleagues' (2007) study was cross-sectional in nature, the purpose of this investigation was to employ a retrospective longitudinal study design to examine the participation rates of Masters swimmers as a function of an individual's constituent year within any 5-year age category over a period of 6 years. Using archived data from the 2003 to 2009 US Masters Short Course National Championships, swimmers' attendance was followed for a period of six consecutive years. Results indicated that a participation-related relative age effect was observed among swimmers who, over a period of 6 years, competed in either at least one championship (N = 2596; Cochran's Q? = 64.16, r(s) = -0.92, both P < 0.0001) or at least three championships (N = 441; Cochran's Q? = 47.51, r(s) = -0.91, both P < 0.0001). Overall, effect size analyses indicated that the odds of a Masters swimmer participating in the championship during the first constituent year of any 5-year age category was more than two times greater than the odds of that athlete participating during the fifth constituent year.     

Teaching human genetics with mustard: rapid cycling Brassica rapa (fast plants type) as a model for human genetics in the classroom laboratory

We have developed experiments and materials to model human genetics using rapid cycling Brassica rapa, also known as Fast Plants. Because of their self-incompatibility for pollination and the genetic diversity within strains, B. rapa can serve as a relevant model for human genetics in teaching laboratory experiments. The experiment presented here is a paternity exclusion project in which a child is born with a known mother but two possible alleged fathers. Students use DNA markers (microsatellites) to perform paternity exclusion on these subjects. Realistic DNA marker analysis can be challenging to implement within the limitations of an instructional lab, but we have optimized the experimental methods to work in a teaching lab environment and to maximize the “hands-on” experience for the students. The genetic individuality of each B. rapa plant, revealed by analysis of polymorphic microsatellite markers, means that each time students perform this project, they obtain unique results that foster independent thinking in the process of data interpretation.     

好朋友

幼儿园，好朋友是在你只剩下黑蜡笔时将红蜡笔借给你用的人。一年级，好朋友是在你嬉玩遇到危险时与你牵手的人。二年级，好朋友是在你受人欺负时能帮助你的人。三年级，好朋友是在你没带午餐时能拿出自己的午餐与你分享的人。四年级，好朋友是在练习方形舞时愿意和你交换舞伴的人。……毕业时，好朋友是关在门里偷偷流泪而在向你祝贺时却能露出灿烂笑容的人。毕业后，好朋友是在你遇到烦恼时帮助你恢复好心情的人；是在你恋恋不舍泪眼模糊时能帮助你收拾上大学的行李并默默拥抱你的人；是让你相信你在这个世界上是被人爱着的人。长大了，好…     

简单的希望

艾米绕过教室对面那个大厅拐角的时候,与迎面走过来的一个五年级男生撞了个正着。     

总冠军的拉链 理查德·汉密尔顿

在他的成长之路上,有两支球队可供选择。一支拥有迈克尔·乔丹,一支没有。但是没有乔丹,他一样能够取得成功。乔丹到底耽误了汉密尔顿还是成全了他,这的确很值得探讨。2000年,如果不是乔丹的到来,也许时至今日,奇才已经打入了季后赛,而汉密尔顿也成为东部顶尖级后卫之一。因为那时他在奇才已可每场交足20 分公粮,俨然一副当家大哥的样子。但这一切都因为乔丹的一句防守不过关而改变。为何会这样,谁都知道他们二人在奇才队的位     

Health informatics in Chile: responding to health reforms

Chile is in the throes of health reforms aimed at ensuring that every person with specified chronic diseases receives timely and high quality care. CITs are crucial to the achievement of this vision because they make it possible to manage information and knowledge in a more efficient way. Until a few years ago, the incorporation of CITs was limited to individual initiatives, but since 2004 there has been a master plan to coordinate this task in the public sector. Some projects are now operative but there is still a long road to travel before getting to our destination. One of the most underdeveloped areas is the clinical applications of health CITs, especially the incorporation of biomedical knowledge to clinical practice. The two biggest challenges facing the Digital Agenda for the health care system are (i) to develop a critical mass of clinicians and health related professionals with expertise in Health Informatics; and (ii) to foster technical integration of the private and public sectors of the health care market.     

Effects of competition, exercise, and mental stress on secretory immunity

It has been suggested that the psychological stress associated with competitive sports events may help to explain the increased susceptibility to respiratory infections due to reductions in secretory immunity. In the current study, we investigated the influence of competitive exercise and psychological stress on secretory immunoglobulin A (s-IgA). Salivary s-IgA and heart rate were measured in 62 healthy young recreationally active men at rest and, in a between-subjects design, following one of four 8-min tasks: mental arithmetic, cycling at workloads of 60 to 180 W (mean = 146 W), mental arithmetic while cycling, or competitive cycling. Mental arithmetic was associated with significant increases in s-IgA concentration (mean = 49 microg.min(-1)) and s-IgA secretion rate (mean = 25 microg.ml(-1)) compared with rest, while mental arithmetic combined with exercise was associated with a significant increase in s-IgA concentration only (mean = 124 microg.min(-1)). In contrast, competitive exercise and exercise alone did not influence s-IgA concentration or secretion rate. Heart rate increased modestly to mental arithmetic (mean = 7 beats.min(-1)) and substantially, and similarly, to the three exercise tasks (mean = 56(62 beats.min(-1)). The hypothesis that the psychological stress of competitive exercise contributes to increased susceptibility to infection via reductions in s-IgA requires further investigation.     

Reply to “Is physical performance (in mice) increased by Veillonella atypica or decreased by Lactobacillus bulgaricus?”

Dear editor,In a recent longitudinal metagenomic study of the gut microbiome in elite athletes,1 we conducted multiple, repeated sampling from runners in the 2015 Boston Marathon as well as sedentary controls approximately 1 week prior to and 1 week after marathon day. We also analyzed an independent cohort of endurance athletes, including Olympic-caliber rowers。     

大自然积木块的现代观点

过去三十年中,在确定物质构造及其运动的明细组分方面,取得了巨大的进展。本之由一位西非物理学家阐明了我们现在对微观的、甚至更细微水平物质构成的了解。他强调加速器在其中的作用,并对可能存在如此多更基本的粒子表示惊讶。