Biomechanics of aggressive inline skating: landing and balancing on a grind rail     

Major MJ  Beaudoin AJ  Kurath P  Hsiao-Wecksler ET 《Journal of sports sciences》2007,25(12):1411-1422

Currently, only epidemiological injury data have been reported for the new extreme sport of aggressive inline skating, or trick skating. No studies have examined the biomechanics of this sport, which involves repetitive jumping and landing from railings, ramps, and ledges, often over 1 m in height. We present results of a pilot study that examined the effect of skater experience and lower extremity biomechanics on energy absorption ability, and observed balance strategies used during two basic tricks. In these tricks, the skater jumps onto an elevated rail and maintains balance while standing in a single position (stall) or sliding along the rail (grind). Lower extremity joint kinematics, impact force characteristics, and general movement behaviours were examined during landing and balance phases. Ten male skaters performed ten stalls and ten frontside grinds on an instrumented grind rail, capable of measuring vertical force. Vertical impact force was found to decrease with increasing skater experience in stalls (r = -0.84, P = 0.002) and grinds (r = -0.84, P = 0.009). This might imply that less-experienced skaters are (subconsciously) more concerned about maintaining balance than refining technique to minimize impact force. Similar to drop landing experiments, peak impact force decreased with increasing knee flexion during stalls (r = -0.65, P = 0.04). During stalls, skaters demonstrated classic balance maintenance strategies (ankle, hip, or multi-joint) depending on trick length. During grinds, skater centre of mass never passed over the rail base of support, suggesting the use of momentum produced from obliquely approaching the rail.  相似文献   

Validation of self-report measures of physical activity: a case study using the New Zealand Physical Activity Questionnaire     

Mackay LM  Schofield GM  Schluter PJ 《Research quarterly for exercise and sport》2007,78(3):189-196

Accurate measurement of physical activity is fundamentally important in epidemiological research of physical activity behavior A widely used telephone-based physical activity questionnaire was compared with other methods of administration and objective measures (pedometers and accelerometers) among 80 adults (43 women). The telephone questionnaire was comparable to both the self-administered form and international telephone-administered equivalent. Although moderate correlation coefficients with objective measures supported the use of the questionnaire, wide prediction intervals generated using Bland Altman methods highlighted large discrepancies between the measures, particularly in the moderate intensity category. These findings illustrate the limitations of correlation coefficients in validation studies and the inaccuracy of self-report questionnaires in measuring physical activity.  相似文献   

Ball launch conditions for skilled golfers using drivers of different lengths in an indoor testing facility     

Wallace ES  Otto SR  Nevill A 《Journal of sports sciences》2007,25(7):731-737

The displacement of the golf ball struck by a driving club is affected by several player characteristics and equipment parameters and their interrelationships. Some modelling and simulation studies have shown a relationship between shaft length and clubhead speed, supported by a few experimental studies. The aim of the present study was to examine the relationship between driver length and ball launch conditions in an indoor test facility using a ball launch monitor. Nine males considered to be skilled golfers participated in the study. Four driving clubs of total length 117, 119, 124, and 132 cm were assembled from commercially available components and were used to strike golf shots while initial ball velocity, backspin rate, and launch angles were measured. Statistical analysis identified a significant difference in initial launch speed due to club length, a significant difference between participants, but no difference between the trials for a given golfer. A positive trend was noted between backspin and launch angle for all four clubs, and significant inverse associations between initial launch speed and backspin rate and launch angle. However, the combined launch conditions associated with increasing length were not considered optimal, with uncontrolled swingweight and moment of inertia effects considered to be limiting factors.  相似文献   

Muscle activation characteristics of tumbling take-offs     

McNeal JR  Sands WA  Shultz BB 《Sports biomechanics / International Society of Biomechanics in Sports》2007,6(3):375-390

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They Sang for Roosevelt: Songs of the People in the Age of FDR     

Patrick J. Maney 《Journal of American culture (Malden, Mass. : 2003)》2000,23(1):85-89

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East Asian pop culture and the trajectory of Asian consumption     

C. J. W.-L. Wee 《Inter-Asia Cultural Studies》2016,17(2):305-315

This article focuses on Chua Beng Huat’s work on the East Asian pop culture that became more prominent in East and Southeast Asia from the 1990s, when the circulation of multilingual and multi-format pop culture started to exceed linguistic, ethnic and national boundaries. It argues that Chua’s work indicates that the pop-cultural production and innovation that support the globalisation and regionalisation processes in East Asia need not be national in origin but can hail from different national origins – and this despite the existing political realities of the region and its history of political fractures. Chua Beng Huat cautions, though, that the national popular can also be marshalled to defeat the border-crossing potential of an inter-Asian pop culture. What is the “Asia” imagined or being represented in such cultural production? Chua’s work is also distinctive in that it deals with the political and economic conditions that underpin mainstream pop consumption as a socio-cultural phenomenon, instead of examining consumption as identity politics. The article concludes by noting the significance that Chua as an institutional builder has played in enabling the study of East Asian pop culture in the region.  相似文献   

Film Criticism,the Cold War,and the Blacklist: Reading the Hollywood Reds Jeff Smith. Berkeley: University of California Press, 2014.          下载免费PDF全文

Martin J. Manning 《Journal of American culture (Malden, Mass. : 2003)》2016,39(3):361-362

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Humility & Humiliation: The Transformation of Franciscan Humour,c.1210–1310     

Peter J. A. Jones 《Cultural and Social History》2018,15(2):155-175

Humiliation and self-ridicule worked as surprisingly important tools of evangelical outreach in the first decades of the Franciscan Order (c.1210–50). According to early Franciscan texts such as the Assisi Compilation (c.1240s) and Jordan of Giano’s Chronica (c.1260), St Francis and his earliest followers sought to win supporters by stripping naked in public, mocking learned preachers and ludicrously imitating animals. Yet within a few decades of the founder’s death this type of humour had been erased from Franciscan texts. Chronicles now omitted references to Francis’s laughter, while humiliating behaviour came to be condemned by Franciscan preachers, chroniclers and theologians alike. From being a means of undermining dignity and reason, joking was now instead celebrated as a tool of upholding these very same values. Describing the nature of this shift, and contextualising it within the evolving institutional priorities of the Franciscans under the leadership of Bonaventure (d.1274), this article will complicate debates about the development of medieval humour, while also reflecting on laughter’s role as a means of resistance to the significant social and cultural upheavals of the 1200s.  相似文献   

Artifacts under Pressure: Effects of Halon Gas Release in a Collection     

Gloria J. Fenner 《Curator: The Museum Journal》1982,25(2):85-90

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A multidimensional motivation instrument     

Margaret E. Uguroglu  Diane P. Schiller  Herbert J. Walberg 《Psychology in the schools》1981,18(3):279-285

Individual empirical studies of motivation show little divergent validity of various factors and call for better measures, especially multidimensional instruments. The same conclusions were reached from a meta analysis of 40 motivation studies by Uguroglu and Walberg (1979). After a study of approximately 50 instruments that measured motivation constructs of social, emotional, and physical self-concept; locus of control; and achievement motivation, among others, a 23-anchored-item questionnaire using a five-point scale was developed that included these factors. The instrument was administered in May of the first and second year to 115 students in grades three through eight. The purpose of the research was to operationalize and field test a motivation instrument using multidimensional measures; also to consider whether any change would occur in the correlation of a multidimensional instrument to various achievement measures over unidimensional ones. Results of the study show the correlations of motivation to academic achievement, test-retest reliability, and the predictive validity of a multidimensional instrument.  相似文献