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   

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   

Excellence and Frontier Research as Travelling Concepts in Science Policymaking     

Tim Flink  Tobias Peter 《Minerva》2018,56(4):431-452

Excellence and frontier research have made inroads into European research policymaking and structure political agendas, funding programs and evaluation practices. The two concepts travelled a long way from the United States and have derived from contexts outside of science (and policy). Following their conceptual journey, we ask how excellence and frontier research have percolated into European science and higher education policies and how they have turned into lubricants of competition that buttress an ongoing reform process in Europe.  相似文献   

Conservation in the United Kingdom     

Peter Winsor 《Cultural Trends》1999,9(33):1-34

British conservation is respected around the world for its excellence, based on a tradition of caring for heritage material, backed up by high‐quality training and research. This paper charts the origins and development of the conservation profession in the United Kingdom and provides a comprehensive overview of the number, location and variety of conservation specialists currently working in the UK. It looks at those working in both the public and private sectors. The findings are based on a number of surveys conducted by the professional bodies and by government agencies such as the Museums & Galleries Commission (MGC). Most of the information relates only to museums, but the most recent survey of conservators by the MGC also looked at provision in libraries and archives.  相似文献   

Report to the directors of the London and Birmingham Railway Company,accompanied by experiments on the transverse strength, &c. of malleable iron,with reference to its use for railway bars     

Peter Barlow 《Journal of The Franklin Institute》1835,20(2):118-127

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Report to the directors of the London and Birmingham Railway Company,accompanied by experiments on the transverse strength, &c. of malleable iron,with reference to its use for railway bars     

Peter Barlow 《Journal of The Franklin Institute》1835,20(3):188-194

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Mechanical jurisprudence.—No. IX     

Peter A. Browne 《Journal of The Franklin Institute》1826,(4):228-236

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Thermal expansion of nickel,monel metal,stellite, stainless steel,and aluminum     

Wilmer H. Souder  Peter Hidnert 《Journal of The Franklin Institute》1922,193(3):398-399

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Elite football on artificial turf versus natural grass: movement patterns, technical standards, and player impressions     

Andersson H  Ekblom B  Krustrup P 《Journal of sports sciences》2008,26(2):113-122

The aim of the present study was to examine the movement patterns, ball skills, and the impressions of Swedish elite football players during competitive games on artificial turf and natural grass. Time - motion analyses (36 observations) and technical analyses (16 team observations) were performed and 72 male and 21 female players completed a questionnaire. No differences were observed between artificial turf and natural grass in terms of total distance covered (mean 10.19 km, s = 0.19 vs. 10.33 km, s = 0.23), high-intensity running (1.86 km, s = 0.10 vs. 1.87 km, s = 0.14), number of sprints (21, s = 1 vs. 22, s = 2), standing tackles (10, s = 1 vs. 11, s = 1) or headers per game (8, s = 1 vs. 8, s = 1), whereas there were fewer sliding tackles (P < 0.05) on artificial turf than natural grass (2.1, s = 0.5 vs. 4.3, s = 0.6). There were more short passes (218, s = 14 vs. 167, s = 12) and midfield-to-midfield passes (148, s = 11 vs. 107, s = 8) (both P < 0.05) on artificial turf than natural grass. On a scale of 0-10, where 0 = "better than", 5 = "equal to", and 10 = "worse than", the male players reported a negative overall impression (8.3, s = 0.2), poorer ball control (7.3, s = 0.3), and greater physical effort (7.2, s = 0.2) on artificial turf than natural grass. In conclusion, the running activities and technical standard were similar during games on artificial turf and natural grass. However, fewer sliding tackles and more short passes were performed during games on artificial turf. The observed change in playing style could partly explain the male players' negative impression of artificial turf.  相似文献   

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

Schumacher YO  Mroz R  Mueller P  Schmid A  Ruecker G 《Journal of sports sciences》2006,24(11):1149-1156

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.  相似文献