Differences between the sexes in the three-dimensional angular rotations of the lumbo-pelvic-hip complex during treadmill running     

Schache AG  Blanch P  Rath D  Wrigley T  Bennell K 《Journal of sports sciences》2003,21(2):105-118

The aims of this experiment were to determine whether there are differences between the sexes in the three-dimensional angular rotations of the lumbo-pelvic-hip complex during running and, if such differences exist, to establish whether factors other than sex can explain the observed differences. A cohort of 44 non-injured runners (22 males, 22 females) who usually ran more than 20 km per week were voluntarily recruited. All trials were conducted on a treadmill at a running speed of 4.0 m x s(-1). Reflective markers were placed over specific anatomical landmarks of the thoraco-lumbar spine, pelvis and femur. Data were captured using a VICON motion analysis system. Females tended to display a greater peak-to-peak oscillation for most of the angular rotations. An offset was the main difference between the male and female group mean waveforms for pelvis anterior-posterior tilt. Forward stepwise regression analysis revealed that sex was the most common variable related to the amplitudes of the angular rotations. Given these results, sport scientists conducting future biomechanical studies using angular data to test hypotheses are advised to be extremely cautious about averaging across male and female participants.  相似文献   

"Ask A Librarian": the experiences of four hospital libraries     

Stone ME  Foxman C  Sostack M  Francar L  Hall P  Markwell LG 《Medical reference services quarterly》2003,22(2):93-105

The librarians at four hospital libraries describe the electronic reference service, "Ask A Librarian," offered at their institutions. The hospitals are vastly different in size and in number of library staff, and offer the "Ask A Librarian" service to different clientele. The article illustrates that both large hospitals with a large library staff and small hospitals with a solo librarian and some volunteers can offer this type of service.  相似文献   

Natural Standard--new integrative medicine database     

Tomasulo P 《Medical reference services quarterly》2003,22(3):33-38

Natural Standard is a new and extremely easy-to-use database consisting of comprehensive evidence-based medicine monographs, and also news brief's on the subject of complementary/alternative medicine therapies. It does not yet contain a huge amount of material, but it is updated frequently, and new information is continuously added. The focus is on the therapeutic "bottom line" of treatment safety and effectiveness. Dosing, Precautions/Adverse Effects, Pregnancy/Lactation Data, and Interactions information is all clearly displayed along with a "Review of the Evidence" table and a discussion summarizing the overall therapeutic value of the treatment modality.  相似文献   

Effects of uncontrollability and failure on the development of learned helplessness in perceptual-motor tasks   总被引：2，自引：0，他引：2  

Gernigon C  Fleurance P  Reine B 《Research quarterly for exercise and sport》2000,71(1):44-54

The aim of this study was to distinguish between the roles of uncontrollability and failure on learned helplessness in a perceptual-motor task. Forty-eight junior high school students were randomly assigned in a 2 x 2 (Controllability: Contingent vs. Yoked Noncontingent Feedback x Type of Outcome: Success vs. Failure) factorial design to complete a gun-shooting task on a moving target using a computer screen. Twelve other participants (control group) simply read a passage. After filling out causal attribution and self-efficacy expectations questionnaires, all participants carried out another gun-shooting task (test task). Results showed that contingency led to higher performances than noncontingency. Success conditions elicited higher self-efficacy expectations than failure conditions. Failure entailed less persistence than success did for participants who had been assigned to the contingency condition. Internalization of failure was negatively correlated with persistence. Comparisons with the control group showed that expectations and performance deficits of learned helplessness were provoked by failure in noncontingent situations; persistence deficits were due to failure in contingent situations. These results reveal that both uncontrollability and failure can be responsible for different forms of learned helplessness.  相似文献   

Life after death: New York state moves to keep dead men's sperm in the family     

Cohen P 《New scientist (1971)》1998,157(2126):23

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Hold the champagne: despite the latest breakthroughs, lab-grown organs are still a long way off     

Cohen P 《New scientist (1971)》1998,160(2160):6

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对美国社区学院课程演变的考察     

Gwyer．Schuyler 《职教论坛》2007,(10X):61-64

美国社区学院的课程直接反映了学生们截然不同的目标。纵观其历史，社区学院已经维持着一种去反映学生抱负模式的变化和地方经济模式改变的课程使命。这正反映着社区学院独有的特点并有可能被当成是其最大的力量。  相似文献   

美国数学教学问题一束     

P.齐菲兹  G.L.布里顿  李俊 《数学教学》1989,(1)

众所周知,当前美国数学教学的主要趋势是“问题解决”(Problem Solving)。这里的一些“问题”在美国是比较常见的。有些在国内也经常碰到,但课堂上用得不多,从培养学生的创造性数学思维来看,这些问题会具有一定的价值。——编者  相似文献   

摄影和摄象技术三维直接线性变换(DLT)再现精度的比较     

P·W·小肯尼迪  D·L·怀特  G·A·史密斯  王宁东  胡征元 《山东体育科技》1990,(4)

记录人体运动的准确性在很大程度上取决于记录方法的精确度。计算出的物体运动学的数值,主要依赖对物体运动记录的准确性。人体运动的生物力学分析经常需要对16mm摄影或摄象技术记录的内容进行分析.由于摄象具有成本低,使用方便,处理时间短的特点,使摄象技术比摄影更具吸引力.然而必须考虑摄象精确度是否与摄影标准相同.要使摄象技术合法地进入人体运动分析领域,摄象记录的精度必须达到摄影记录的  相似文献   

超重元素的合成     

Armb.  P  郭爱伦 《科学中国》1989,(9):9-16

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