The effect of 14 weeks of vitamin D3 supplementation on antimicrobial peptides and proteins in athletes     

Cheng-Shiun He  William D. Fraser  Jonathan Tang  Kirsty Brown  Stephen Renwick  Jay Rudland-Thomas 《Journal of sports sciences》2016,34(1):67-74

Heavy training is associated with increased respiratory infection risk and antimicrobial proteins are important in defence against oral and respiratory tract infections. We examined the effect of 14 weeks of vitamin D₃ supplementation (5000 IU/day) on the resting plasma cathelicidin concentration and the salivary secretion rates of secretory immunoglobulin A (SIgA), cathelicidin, lactoferrin and lysozyme in athletes during a winter training period. Blood and saliva were obtained at the start of the study from 39 healthy men who were randomly allocated to vitamin D₃ supplement or placebo. Blood samples were also collected at the end of the study; saliva samples were collected after 7 and 14 weeks. Plasma total 25(OH)D concentration increased by 130% in the vitamin D₃ group and decreased by 43% in the placebo group (both P = 0.001). The percentage change of plasma cathelicidin concentration in the vitamin D₃ group was higher than in the placebo group (P = 0.025). Only in the vitamin D₃ group, the saliva SIgA and cathelicidin secretion rates increased over time (both P = 0.03). A daily 5000 IU vitamin D₃ supplement has a beneficial effect in up-regulating the expression of SIgA and cathelicidin in athletes during a winter training period, which could improve resistance to respiratory infections.  相似文献   

Perceptual-cognitive expertise of handball coaches in their young and middle adult years     

Lennart Fischer  Joseph Baker  Rebecca Rienhoff  Bernd Strauß  Judith Tirp  Dirk Büsch 《Journal of sports sciences》2016,34(17):1637-1642

There is little research investigating the maintenance of perceptual-cognitive expertise in general and even less comparing coaches of different ages. The aim of this study was to test for perceptual-cognitive differences between age groups, licence levels, and their interaction. This study investigated differences in skilled performance between young and middle-aged coaches of three different skill levels. Participants performed an accuracy-oriented pattern recall (mean distance in pixel) and a time-oriented flicker test (mean detection time in ms). There were some significant differences between age groups and between skill groups for both tests, but no interactions. For the pattern recall test, the effect sizes were larger for skill level differences, while for the flicker test effects were larger for ageing. These results suggest coaches are able to maintain accuracy skills better than reaction timed tasks. This is in line with findings on speeded performance in general populations, which show declines with age. Moreover, results also support findings on perceptual expertise in skills where accuracy was important.  相似文献   

Performance differences when using 26- and 29-inch-wheel bikes in Swiss National Team cross-country mountain bikers     

Thomas Steiner  Beat Müller  Thomas Maier  Jon Peter Wehrlin 《Journal of sports sciences》2016,34(15):1438-1444

The purpose of this study was to analyse the effect of bike type – the 26-inch-wheel bike (26“ bike) and the 29-inch-wheel bike (29“ bike) – on performance in elite mountain bikers. Ten Swiss National Team athletes (seven males, three females) completed six trials with individual start on a simulated cross-country course with 35 min of active recovery between trials (three trials on a 26“ bike and three trials on a 29“ bike, alternate order, randomised start-bike). The course consisted of two separate sections expected to favour either the 29“ bike (section A) or the 26“ bike (section B). For each trial performance, power output, cadence and heart rate were recorded and athletes’ experiences were documented. Mean overall performance (time: 304 ± 27 s vs. 311 ± 29 s; P < 0.01) and performance in sections A (P < 0.001) and B (P < 0.05) were better when using the 29“ bike. No significant differences were observed for power output, cadence or heart rate. Athletes rated the 29“ bike as better for performance in general, passing obstacles and traction. The 29“ bike supports superior performance for elite mountain bikers, even on sections supposed to favour the 26“ bike.  相似文献   

Intrinsic Versus Extrinsic Motivation: An Approach/Avoidance Reformulation     

Martin V. Covington  Kimberly J. Müeller 《Educational Psychology Review》2001,13(2):157-176

The main purpose of this article is to advance an alternative perspective on the relationship between intrinsic and extrinsic motivation, and in particular to examine critically the assertion that these processes are antagonistic such that the will to learn for its own sake is inhibited by the presence of extrinsic, tangible rewards and incentives such as school grades. The presumption of an antagonistic relationship largely depends on the theoretical perspective adopted. An alternative interpretation based on need achievement theory leads to distinctly different conclusions. Exploring this new perspective allows one to identify both the conditions under which intrinsic motives may coexist with extrinsic motives as well as to consider some of the means by which intrinsic motives and caring about learning can be stimulated in their own right in school settings.  相似文献   

Bilateral practice improves dominant leg performance in long jump     

Anne Focke  Sina Spancken  Christian Stockinger  Benjamin Thürer  Thorsten Stein 《European Journal of Sport Science》2016,16(7):787-793

Benefits of bilateral practice both for the non-dominant and for the dominant body side have been shown in several studies. Thereby, most of the studies included movement tasks of the upper extremity or investigated sports games in which the ability of acting bilaterally is an essential basis for success and, thus, a bilateral practice is reasonable anyway. Individual unilaterally performed sports including movement tasks of the lower extremity are rarely investigated. Therefore, the aim of our study was to test if contralateral transfer due to bilateral practice can be found in an unilaterally performed sport including the lower extremity. We trained and tested 61 adolescent athletes in long jump to compare the jumping performance of the dominant leg after a 12-week practice period between two groups: a bilateral practice group that practiced specific long jump exercises with both the dominant and non-dominant leg and an unilateral practice group that practiced specific long jump exercises only with the dominant leg. Results showed a superior effect of bilateral practice compared to unilateral practice regarding the jumping performance of the dominant leg. The performance increase at post-test and retention-test for the dominant limb was significantly higher for the bilateral practice group (pre-to-post: 5.2%, pre-to-retention: 7.4%) compared to the unilateral practice group (pre-to-post: 3.4%, pre-to-retention: 4.5%). Thus, bilateral practice should be established in the early practice programmes of track and field athletes to improve the performance of the dominant take-off leg.  相似文献   

硝酸法处理废硬质合金回收金属钴和碳化钨     

汤青云  段冬平 《湖南城市学院学报》1996,(6)

介绍了用硝酸法处理废硬质合金，回收金属钴和碳化钨的方法，并且设计了对废气氛氧化物的处理方法，消除了对环境的污染。是一种工艺简单，投资省，成本低，能耗少，污染小的回收工艺。  相似文献   

中职教师在职攻读硕士学位问题探讨   总被引：4，自引：0，他引：4  

饶异伦  唐玉凤 《职业技术教育》2006,27(7):30-32

近年来,中职教师在职攻读硕士学位的过程中,出现了许多不尽人意之处,如学员学前背景、学前动机、学中态度、学中效果、学后质量等差异较大,影响了培养质量。为此,有必要加强与学员所在单位的联系与合作;加强对学员的管理与规范;以人为本,全面提高学员综合素质和学术价值观;优化导师的整体指导资源,提升导师小组的指导能力。  相似文献   

Visualization of structured packing with laser induced fluorescence technique: Two-dimensional measurement of liquid concentration distribution     

刘伯潭  申言同  张会书  刘春江  唐忠利  袁希钢 《天津大学学报(英文版)》2016,22(5):466-472

A method of using laser induced fluorescence(LIF)technique was applied to two-dimensional measurement of the liquid concentration distribution in the 250Y structured packing sheet. The experimental structured packing sheet was made of perspex so that the laser could pass through it. The visualization of the distribution of the liquid concentration in the structured packing sheet was realized. The calibration of the thickness and liquid concentration was carried out firstly and the regression formula I=kcd was acquired, in which concentration c and the liquid film thickness d were both considered. Then the liquid feed of uniform tracer(rhodamine)concentration entered the perspex structured packing from the top under different spraying densities. The corresponding thickness of liquid film on the packing was calculated. Finally, tracer(rhodamine)with a high concentration was injected only at one fixed point of the structured packing under different spraying densities of the liquid. With the known liquid film thickness, the concentration distribution of the tracer can be calculated inside the structured packing sheet.  相似文献   

英汉词汇的民族文化特征和语用差异     

唐芸 《毕节学院学报》2001,19(4):38-39

词汇是语言的主要构素;词汇不仅有其字面意义,还有其内涵意义。在语言中,词汇和语义最能充分、生动地反映出生活的不同侧面。在跨文化交际中,词汇在不同的语境和不同的历史条件下会表现出不同的内涵和语用差异,这既反映出不同的民族文化,也反映出词汇在不同民族文化中特有的文化内涵。  相似文献   

多元智能与幼儿英语教学     

唐文杰  罗依娜 《学前教育研究》2006,(Z1)

近几年来,幼儿英语教学在我国获得蓬勃发展,但是由于缺少先进的科学理论指导,目前很多幼儿园的英语教学定位不准,目标不明确,给人感觉英语教学好像游离于学前教育体系之外。如何真正把英语教学纳入学前教育体系之中,已成为摆在我们面前的新课题。本文认为,加德纳的多元智能理论符合我国学前教育的培养目标和要求,用它来指导英语教学,能激发幼儿学习英语的兴趣,促进多种智能开发,提高整体素质,从而推进我国幼儿教育事业的发展。  相似文献