让我们更多地认识城市与城市研究(二)

本文是美国圣地亚哥大学教授詹姆斯·A·克莱普2008年4月在北京城市学院的演讲,演讲共三场。为便于读者全面地理解克莱普教授的演讲内容,全部演讲内容被编译成一篇。本文是根据演讲记录稿整理后,经克莱普教授本人审定英文稿编译。     

The relationship between peak height velocity and physical performance in youth soccer players

Longitudinal changes in height, weight and physical performance were studied in 33 Flemish male youth soccer players from the Ghent Youth Soccer Project. The players' ages at the start of the study ranged from 10.4 to 13.7 years, with a mean age of 12.2 +/- 0.7 years. Longitudinal changes were studied over a 5 year period. Peak height velocity and peak weight velocity were determined using non-smoothed polynomials. The estimations of peak height velocity, peak weight velocity and age at peak height velocity were 9.7 +/- 1.5 cm x year-1, 8.4 +/- 3.0 kg x year-1 and 13.8 +/- 0.8 years, respectively. Peak weight velocity occurred, on average, at the same age as peak height velocity. Balance, speed of limb movement, trunk strength, upper-body muscular endurance, explosive strength, running speed and agility, cardiorespiratory endurance and anaerobic capacity showed peak development at peak height velocity. A plateau in the velocity curves was observed after peak height velocity for upper-body muscular endurance, explosive strength and running speed. Flexibility exhibited peak development during the tear after peak height velocity. Trainers and coaches should be aware of the individual characteristics of the adolescent growth spurt and the training load should also be individualized at this time.     

Pedometer reliability, validity and daily activity targets among 10- to 15-year-old boys

The aims of this study were to: (1) determine whether the number of pedometer counts recorded by adolescents differs according to the adiposity of the participant or location on the body; (2) assess the accuracy and reliability of pedometers during field activity; and (3) set adolescent pedometer-based physical activity targets. Seventy-eight 11- to 15-year-old Boy Scouts completed three types of activity: walking, fast walking and running. Each type was performed twice. Participants wore three pedometers and one activity monitor during all activities. Participants were divided into groups of normal weight (BMI < 85th percentile) and at risk of being overweight (BMI > or = 85th percentile). Intra-class correlations across the three activities indicated reliability (r = 0.51 - 0.92, P < 0.001). This conclusion was supported by narrow limits of agreement that were within a pre-set range that was practically meaningful. Multivariate analysis of covariance indicated adiposity group differences, but this difference was a function of the increased stature among the larger participants (P < 0.001). Ordinary least-squares regression models and multi-level regression models showed positive associations between the number of pedometer and activity monitor counts recorded by the three groups of participants during all activities (all P < 0.001). The mean number of counts recorded for all participants during the fast walk was 127 counts per minute. In conclusion, the pedometers provided an accurate assessment of adolescent physical activity, and a conservative estimate of 8000 pedometer counts in 60 min is equivalent to 60 min of moderate to vigorous physical activity.     

Success in elite cycling: A prospective and retrospective analysis of race results

The development of peak performances is a main research focus in sports science. It is unclear how many former top junior athletes achieve success in the elite class later. The aim of the present study was to examine the careers of athletes who participated in major junior or adult/elite cycling events using prospective and retrospective analysis of competition results. The official results of major junior (age < or = 18 years) and elite (age > 18 years) cycling races from 1980 to 2004 were analysed. Age-related aspects, career lengths, and success were compared between riders who presented results in both junior and elite races (JUNIOR ELITE) and riders who had no junior race results (ELITE ONLY). Altogether, 27,454 results of 8004 athletes from 108 countries were collected. We found that 29.4% of the elite athletes had participated in junior World Championships, and that 34% of the participants in junior World Championships later participated in major elite competitions. JUNIOR ELITE athletes are significantly more successful in several cycling disciplines and have their first and last elite result at a younger age than ELITE ONLY athletes. No difference was found in career lengths. The data presented here emphasize the importance of long-term training programmes in the development of peak performance in cycling.     

论教师与学生的关系

教师与学生关系的性质对学生自觉性和自尊心的形成有极重要的意义.教育工作的实际经验指出,假定教师能对个别学生表扬他的任何积极方面,那末,学生就能开始注意并培养自已的这些优点. 在很多情况中,学生对自己力量没有自信心的原因,就是在教师方面对他们的能力估计不足。这个事实指出了教师与学生建立的关系上所产生的感化作用是多麽巨大,它不仅能够破坏个别学生,而且还能破坏全级学生对自己力量的信任.女教师纳·克,为了对自己的工作做得不好作辩护,经常向学生们说,他们没有能力,总是不肯好好学习等话。结果,学生们本来能够学习得很好的,丧失了自信心,这样,他们就学习得更坏,成为学校里成绩最坏的一班。这就是说:女教师纳·克只看见了学生的弱点。但是在某一时期内,这个女教师的位置上派来了另一位新教师,她很有经验而且也富有钻研心.最初几天,她注意了学生思想上已有的习惯,和他们一班所以在“学校中最坏”的原因。她就在班上开始培养学生对自己力量的自信心.她从思想上去影响学生,告诉他们,如果能够坚持和系统地工作,便会学习得很好.女教师与学生们的新的关系和正确地组织教学工作,获得了非常良好的成绩.学生们对待自己也不同了,他们信任了自己的力量,对未来的发展前途表现了无限向往.这一班“眼看着”有了转变。过了几个月,学生们自己     

语文课中自然知识的综合复习

在教学过程中进行经常而有系统的复习是学生进步条件之一。在语文课中的自然知识也应当进行综合复习的。在这种课上,只是复习已教过的最基本的和最重要的材料:明确学生的概念,扩大学生的理解力,补足学生的知能。一至三年级的综合复习课大概每一堂课可以复习一课。进行综合复习课时,必须尽量利用过去所应用过的一切教材(例如:实物教材:“活的和干燥的植物和动物标本”、图片、表格、模型、自然历、地图等等)。     

ЛК—3号飞向月球——一个假想的科学故事

一九……年五月十一日二十点十二分莫斯科时间。舱中映射着喷气式发动机和喷出的红色火焰的反照。仅历数分之一秒我们的“ЛК—3”号便稳静地与地球的新卫星——小月球分离开了。小月球是苏维埃人用自己的智慧和双手创造出来的。它是一切星球间航行艇的起点。     

和死亡作鬥爭

“蘇聯共產黨和蘇聯政府對於改善人民的物質生活,提高人民的文化水平和保護勞動人民的健康非常關心。在世界上没有一個國家像蘇聯具有這樣分佈廣闊的普及免費醫療的機構。在世界上也没有一個國家,醫學在那里比在蘇聯更順利地獲得發展。十九次黨代表大會的指示中曾這樣說:“醫學工     

地球与行星的构造

对於研究地球——我们生活在其上面的行星——构造的学者们来说。能够直接研究到的仅仅是地球的极薄的表面层。这一层仅祇含有地球全部物质的百分之一还不到。关於地球的内部构造,只得根据间接的标志求判断——根据内部密度的估计,根据地震波的传播性质和传播速度等等。这时候对於研究家偿显示重大帮助的是关于别的和地球相近的太阳系里天体的知识——例如行星、陨星和彗星。     

實用主義——帝國主義的反動哲學(续)

按照實用主義者的主觀唯心論說來,環境並不是什麽真實存在的東西,而是一種完全主觀的東西。實用主義哲學的這一方面,特別被杜威充分表現出來,他的觀點也正是席勒所抱的觀點。杜威和席勒一致認為人類的一切生活是由各種‘情况’所產生的。生活在這一種或那一種生活情况中的人,總是要努力從這種情况中找到最有利的出路;他自己抱着一種確定的、而總是自私的目的,並努力設法用各種