排序方式： 共有38条查询结果，搜索用时 15 毫秒
1.
Matteo Zago Andrea Gianluca Piovan Isabella Annoni Daniela Ciprandi F. Marcello Iaia 《Journal of sports sciences》2016,34(5):411-419
Dribbling speed in soccer is considered critical to the outcome of the game and can assist in the talent identification process. However, little is known about the biomechanics of this skill. By means of a motion capture system, we aimed to quantitatively investigate the determinants of effective dribbling skill in a group of 10 Under-13 sub-elite players, divided by the median-split technique according to their dribbling test time (faster and slower groups). Foot-ball contacts cadence, centre of mass (CoM), ranges of motion (RoM), velocity and acceleration, as well as stride length, cadence and variability were computed. Hip and knee joint RoMs were also considered. Faster players, as compared to slower players, showed a 30% higher foot-ball cadence (3.0 ± 0.1 vs. 2.3 ± 0.2 contacts · s?1, P < 0.01); reduced CoM mediolateral (0.91 ± 0.05 vs. 1.14 ± 0.16 m, P < 0.05) and vertical (0.19 ± 0.01 vs. 0.25 ± 0.03 m, P < 0.05) RoMs; higher right stride cadence (+20%, P < 0.05) with lower variability (P < 0.05); reduced hip and knee flexion RoMs (P < 0.05). In conclusion, faster players are able to run with the ball through a shorter path in a more economical way. To effectively develop dribbling skill, coaches are encouraged to design specific practices where high stride frequency and narrow run trajectories are required. 相似文献
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Talis Tisenkopfs Ilona Kunda Sandra šūmane Gianluca Brunori Laurens Klerkx Heidrun Moschitz 《The Journal of Agricultural Education and Extension》2015,21(1):13-33
AbstractPurpose: The paper explores the role of boundary work and boundary objects in enhancing learning and innovation processes in hybrid multi-actor networks for sustainable agriculture (LINSA).Design/Methodology/Approach: Boundary work in LINSA is analysed on the basis of six case studies carried out in SOLINSA project under a common methodology. In developing typologies of boundary work and objects, a grounded approach is used.Findings: LINSA analysis demonstrates the dynamic character, diverse forms and multiple functions of boundary work and objects in three domains: learning, innovation, and sustainability. Addressing specific types of goals and actors leads to specific types of boundary work and boundary objects. Context-appropriate boundary work allows aligning differing actor attitudes, gaining increased external support, and developing LINSA. The concepts of boundary work and boundary objects are relevant in a broad range of divergent LINSA settings. Boundary work has its limitations, but its facilitation supports reaching LINSA goals.Practical Implications: The paper proposes recognising context-appropriate forms of boundary work and skilful use of emerging boundary objects to both promote internal consolidation of LINSA and effective external communication to foster learning and innovation for sustainability.Originality/Value: The paper provides insights into the forms, dynamic and outcomes of boundary work in LINSA in three key domains: developing shared knowledge base, co-producing innovation and negotiating sustainability. 相似文献
3.
Björn Sjögren Robert Thornberg Linda Wänström Gianluca Gini 《Psychology in the schools》2020,57(11):1710-1723
This study examined whether defending and passive bystanding during peer victimization episodes were associated with individual- and classroom-level efficacy to stop peer victimization. Self-report survey data were analyzed from 1,467 Swedish fourth-grade students (mean age = 10.55) from 100 classrooms in 63 schools. Multilevel analyses revealed that, when witnessing peer victimization, students more often defended victims if they were high in defender self-efficacy and if they belonged to classrooms high in collective efficacy. In contrast, students were more likely to remain passive if they were low in defender self-efficacy and if they belonged to classrooms low in collective efficacy. Taken together, our findings suggest that efficacy beliefs both at the individual and at the classroom level contribute to explaining variability in students' bystander behaviors, which has potential implications for prevention and intervention work. 相似文献
4.
Ruth Ippoliti 《家庭与家教》2002,(5):19-19
“越洋专递”栏目甫一亮相,反响热烈。我们陆续收到了南京、太原、合肥等地同学的来信,孩子们和他们的父母通过各种方式表达了结交异国笔友的美好愿望。经过认真挑选,来自山西省太原市五中的李楠成为第一位幸运儿,本刊下期将刊登她的个性档案及写给美国小姑娘Demi的信。我们已和美国加州John Glenn中学取得联系,美国学生对此也很重视,不仅信中附有照片,有的还寄来可爱的小礼物。有兴趣的同学可填写笔友登记表,我们将针对你的情况,按照你的要求为你推荐笔友,并不定期地登载互通的信件及笔友通讯录。来信可附近照。在适当的时候。本刊将举办中美学生互访和夏令营活动,进一步缩短东西方的距离。本刊将为你搭起一座七彩桥,帮助你了解异域文化,结识异国笔友,和同龄人互相学习,携手共进。 相似文献
5.
This paper proposes a sensorless fault-tolerant control strategy solving the tracking problem of the maximum delivered power characteristic for a wind energy conversion system equipped with a permanent magnet synchronous generator. A previously published control scheme ensuring the maximum power efficiency of the wind turbine, not requiring feedback information about rotor speed and position, and about wind velocity, is here extended to make the control scheme fault-tolerant with respect to possible electrical faults affecting the equations of the permanent magnet synchronous generator (PMSG) in the original (α, β) frame. The control law is based on a number of interconnected nonlinear observers. Closed loop asymptotic vanishing of the observation errors is proved. The proposed control solution has been validated on the National Renewable Energy Laboratory (NREL) 5-MW three-blade wind turbine model. 相似文献
6.
SYNOPSISHigh-quality parental caregiving promotes children’s development from their day of birth or even earlier. Whether there are ways to predict, and ultimately enhance, parental caregiving quality during the prenatal stages of development has been less well understood. This circumstance is even truer when things do not go according “to plan.” In this commentary, we explore two possible scenarios, perhaps unexpected for expectant parents, that can affect children’s development: (1) postpartum parental displays of atypical behaviors and parental caregiving strategies (i.e., maternal/paternal depression) and (2) postpartum child displays of atypical behaviors (i.e., autism spectrum disorder). 相似文献
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Cinthya Ippoliti 《International Information and Library Review》2017,49(4):304-309
Utilizing the concepts of change management and intentional change theory, this column delves into the issues facing new liaison roles and provides tips for those who are undergoing a similar process through a lens of organizational change that addresses reviewing what is working, as well as what is not, developing a clear vision and direction, breaking down the change into smaller segments, cultivating a sense of identity through shared purpose, and supporting new habits. 相似文献
9.
Gianluca Demartini Claudiu S. Firan Tereza Iofciu Ralf Krestel Wolfgang Nejdl 《Information Retrieval》2010,13(5):534-567
Entity Retrieval (ER)—in comparison to classical search—aims at finding individual entities instead of relevant documents.
Finding a list of entities requires therefore techniques different to classical search engines. In this paper, we present
a model to describe entities more formally and how an ER system can be build on top of it. We compare different approaches
designed for finding entities in Wikipedia and report on results using standard test collections. An analysis of entity-centric
queries reveals different aspects and problems related to ER and shows limitations of current systems performing ER with Wikipedia.
It also indicates which approaches are suitable for which kinds of queries. 相似文献
10.
Gianluca Vernillo Aldo Savoldelli Andrea Zignoli Spyros Skafidas Alessandro Fornasiero Antonio La Torre 《Journal of sports sciences》2015,33(19):1998-2005
This study aimed to determine whether the fatigue induced by a mountain ultramarathon (MUM) led to changes in energy cost and kinematic during level and graded running. Pre- and post-race, 14 ultratrail runners ran on a level, uphill (5%) and downhill (5%) treadmill at 10 km · h?1. Kinematic data were acquired using a photocell system. Post-race, the downhill energy cost increased by 13.1% (P < 0.001). No change was noted in level and uphill running. Duty factor and stride frequency were increased, whereas swing time, cycle time and stride length were decreased in all conditions (P < 0.05). Contact time was increased and the rate of force generation was decreased only in the uphill and downhill conditions (P < 0.05). Positive correlations were observed between performance time and the pre- to post-changes in the energy cost of level (r = 0.52, P = 0.04) and uphill running (r = 0.50, P = 0.04). MUM-induced fatigue resulted in physiological and spatiotemporal changes, though the response to fatigue varied considerably between running conditions. These changes resulted in a significant increment only in the downhill energy cost. Incorporating downhill locomotion in the training programmes of ultratrailers may help to improve performance-related physiological and biomechanical parameters. 相似文献