Coordination pattern of baseball pitching among young pitchers of various ages and velocity levels

This study compared the whole-body movement coordination of pitching among 72 baseball players of various ages and velocity levels. Participants were classified as senior, junior, and little according to their age, with each group comprising 24 players. The velocity levels of the high-velocity (the top eight) and low-velocity (the lowest eight) groups were classified according to their pitching velocity. During pitching, the coordinates of 15 markers attached to the major joints of the whole-body movement system were collected for analysis. Sixteen kinematic parameters were calculated to compare the groups and velocity levels. Principal component analysis (PCA) was conducted to quantify the coordination pattern of pitching movement. The results were as follows: (1) five position and two velocity parameters significantly differed among the age groups, and two position and one velocity parameters significantly differed between the high- and low-velocity groups. (2) The coordination patterns of pitching movement could be described using three components, of which the eigenvalues and contents varied according to age and velocity level. In conclusion, the senior and junior players showed greater elbow angular velocity, whereas the little players exhibited a wider shoulder angle only at the beginning of pitching. The players with high velocity exhibited higher trunk and shoulder rotation velocity. The variations among groups found using PCA and kinematics parameter analyses were consistent.     

论亚里士多德的"第一推动者"

《物理学》中的“第一推动者”是在自然哲学内作为实体的不动的推动者,而《形而上学》中的“第一推动者”是在“理性-神”作为实体意义上来表述的。亚氏通过对“第一推动者”的论述,完成了从自然哲学到形而上学的过渡。     

Coming to know about the body in Human Movement Studies programmes

This paper explores how a group of undergraduate Human Movement Studies (HMS) students learnt to know about the body during their four-year academic programme at an Australian university. When students begin an undergraduate programme in HMS they bring with them particular constructions, ideas and beliefs about their own bodies and about the body in general. Those ideas and beliefs are often challenged, disrupted or reinforced according to discourses and practices to which students are exposed and which they experience throughout their programme of study. The courses that these students take in their in HMS degree programme present to them different perspectives about health and the body. Some perspectives take the status of taken-for-granted truths and others are dismissed or ignored. Taking a Foucauldian perspective, this paper explores the dominant discourses and practices to which this group of students was exposed during their four years of academic formation, and the influences that this exposure might have upon their construction of the body and their formation as pre-service Health and Physical Education (HPE) teachers. The participants in this study were 14 students, 11 females and 3 males, aged between 18 and 26 at the time of the first interview. The data used for this paper were taken from a larger study and were analysed using a content analysis approach. Results suggest that some students may be heavily influenced by certain practices and discourses during their programme of studies, and that they embody dominant discourses of health. Furthermore, a possible change of thinking may occur across their academic programme, as a consequence of their engagement with a few alternative discourses presented during their academic programme, disrupting some of their previous beliefs and knowledge.     

Ankle and knee kinetics between strike patterns at common training speeds in competitive male runners

The purpose of this study was to investigate the interaction of foot strike and common speeds on sagittal plane ankle and knee joint kinetics in competitive rear foot strike (RFS) runners when running with a RFS pattern and an imposed forefoot strike (FFS) pattern. Sixteen competitive habitual male RFS runners ran at two different speeds (i.e. 8 and 6?min?mile^?1) using their habitual RFS and an imposed FFS pattern. A repeated measures analysis of variance was used to assess a potential interaction between strike pattern and speed for selected ground reaction force (GRF) variables and, sagittal plane ankle and knee kinematic and kinetic variables. No foot strike and speed interaction was observed for any of the kinetic variables. Habitual RFS yielded a greater loading rate of the vertical GRF, peak ankle dorsiflexor moment, peak knee extensor moment, peak knee eccentric extensor power, peak dorsiflexion and sagittal plane knee range of motion compared to imposed FFS. Imposed FFS yielded greater maximum vertical GRF, peak ankle plantarflexor moment, peak ankle eccentric plantarflexor power and sagittal plane ankle ROM compared to habitual RFS. Consistent with previous literature, imposed FFS in habitual RFS reduces eccentric knee extensor and ankle dorsiflexor involvement but produce greater eccentric ankle plantarflexor action compared to RFS. These acute differences between strike patterns were independent of running speeds equivalent to typical easy and hard training runs in competitive male runners. Current findings along with previous literature suggest differences in lower extremity kinetics between habitual RFS and imposed FFS running are consistent among a variety of runner populations.     

Effect of gender on trunk and pelvis control during lateral movements with perturbed landing

In lateral reactive movements, core stability may influence knee and hip joint kinematics and kinetics. Insufficient core stabilisation is discussed as a major risk factor for anterior cruciate ligament (ACL) injuries. Due to the higher probability of ACL injuries in women, this study concentrates on how gender influences trunk, pelvis and leg kinematics during lateral reactive jumps (LRJs). Perturbations were investigated in 12 men and 12 women performing LRJs under three different landing conditions: a movable landing platform was programmed to slide, resist or counteract upon landing. Potential group effects on three-dimensional trunk, pelvic, hip and knee kinematics were analysed for initial contact (IC) and the time of peak pelvic medial tilt (PPT). Regardless of landing conditions, the joint excursions in the entire lower limb joints were gender-specific. Women exhibited higher trunk left axial rotation at PPT (women: 4.0 ± 7.5°, men: ?3.1 ± 8.2°; p = 0.011) and higher hip external rotation at both IC and PPT (p < 0.01). But women demonstrated higher knee abduction compared to men. Men demonstrated more medial pelvic tilt at IC and especially PPT (men: –5.8 ± 4.9°, women: 0.3 ± 6.3°; p = 0.015). Strategies for maintaining trunk, pelvis and lower limb alignment during lateral reactive movements were gender-specific; the trunk and hip rotations displayed by the women were associated with the higher knee abduction amplitudes and therefore might reflect a movement strategy which is associated with higher injury risk. However, training interventions are needed to fully understand how gender-specific core stability strategies are related to performance and knee injury.     

试论义和团运动对中国早期现代化进程的作用

探讨了义和团运动对中国早期现代化进程所起的作用 ,义和团运动加速了中国资产阶级民主革命的迅速到来 ,客观上为民族资本主义工业发展创造了条件 ,并促使了中国社会意识形态的全面变革     

抗战时期华侨抵制日货运动及其贡献

日本发动全面侵华战争后，海外华侨为了抗日救国，在侨居地开展了大规模的不买不卖不用日货和不为日本人工作、阻止军用物资运日的抵制运动，在经济上有力打击了日本侵略者，削弱了日本军用物资的供应，配合了祖国抗战。海外华侨的抵制运动是中华民族抗击日本帝国主义侵略斗争的重要组成部分。     

被束缚的想象力——五四小说新论

由于对科学理性的极力崇拜和对西方写实主义的片面追求,五四新小说的想象力曾一度处在现实真实、科学常识和现实意图的束缚之下。传统小说的神秘想象瞬间绝踪灭迹;西方现代派的非理性想象也失去了被理解的土壤。想象力被小心翼翼的局限在合科学性、合现实真实性的狭小范围之内。再现性想象成了作家们创作的主要途径。一般说来,缺乏自由想象的小说也是缺乏真正的表现力的小说。被束缚的想象力最终又影响到了五四新小说对生活本质的把握和艺术审美的追求。     

转型、困惑与出路——美国“进步主义运动”略论

19、20世纪之交美国社会经济的巨变和转型促成了“进步主义运动”的兴起。运动的倡导者源自美国社会各主要阶层和集团，共同的社会责任感和危机意识将其维系在一起。作为自由主义改革的集大成者，这场运动从19世纪后期美国的各类改革实践中汲取营养，以之作为渊源和动力并有所超越。由于该时期美国社会转型的复杂性，“进步主义运动”也蕴涵诸多悖论，对其加以准确释读对于观照普遍意义上的资本主义转型不无裨益。     

Clinical detection and movement recognition of neuro signals

INTRODUCTION Human limbs are complex, delicate systems.Their reconstruction, both for appearance and forfunction compensations, proves to be complicatedprojects. With the development of science and tech-nology, both researchers and disabilities hope to haveartificial limb much more perky, comfortable, dex-terous and effective. Although thousands of pros-thetic limbs are commercially available worldwide,most of them, from mechanical styles to electricstyles, from motion controlled t…