The kinematic differences between accurate and inaccurate squash forehand drives for athletes of different skill levels     

Benjamin K. Williams  Ross H. Sanders  Joong Hyun Ryu  Philip Graham-Smith  Peter J. Sinclair 《Journal of sports sciences》2020,38(10):1115-1123

ABSTRACT

To maintain the accuracy of squash shots under varying conditions, such as the oncoming ball’s velocity and trajectory, players must adjust their technique. Although differences in technique between skilled and less-skilled players have been studied, it is not yet understood how players vary their technique in a functional manner to maintain accuracy under varying conditions. This study compared 3-dimensional joint and racket kinematics and their variability between accurate and inaccurate squash forehand drives of 9 highly skilled and 9 less-skilled male athletes. During inaccurate shots, less-skilled players hit the ball with a more open racket, demonstrating a difference in this task-relevant parameter. No joint kinematic differences were found for accuracy for either group. Coordinated joint rotations at the elbow and wrist both displayed a “zeroing-in” effect, whereby movement variability was reduced from the initiation of propulsive joint rotation to a higher consistency at ball-impact; potentially highlighting the “functionality” of the variability prior to the impact that enabled consistent task-relevant parameters (racket orientation and velocity) under varying conditions. Further, highly skilled players demonstrated greater consistency of task-relevant parameters at impact than less-skilled players. These findings highlight the superior ability of highly skilled players to adjust their technique to achieve consistent task-relevant parameters and a successful shot.  相似文献   

The Developmental Sequence and Relations Between Gesture and Spoken Language in Toddlers With Autism Spectrum Disorder     

Meagan R. Talbott  Gregory S. Young  Jeff Munson  Annette Estes  Laurie A. Vismara  Sally J. Rogers 《Child development》2020,91(3):743-753

In typical development, gestures precede and predict language development. This study examines the developmental sequence of expressive communication and relations between specific gestural and language milestones in toddlers with autism spectrum disorder (ASD), who demonstrate marked difficulty with gesture production and language. Communication skills across five stages (gestures, word approximations, first words, gesture-word combinations, and two-word combinations) were assessed monthly by blind raters for toddlers with ASD participating in an randomized control trial of parent-mediated treatment (N = 42, 12–30 months). Findings revealed that toddlers acquired skills following a reliable (vs. idiosyncratic) sequence and the majority of toddlers combined gestures with words before combining words in speech, but in contrast to the pattern observed in typical development, a significant subset acquired pointing after first words.  相似文献   

Static and dynamic accuracy of a magnetic-inertial measurement unit used to provide racket swing kinematics     

Benjamin Kane Williams  Ross H. Sanders  Joong Hyun Ryu  Pitre C. Bourdon  Philip Graham-Smith  Peter J. Sinclair 《Sports biomechanics / International Society of Biomechanics in Sports》2019,18(2):202-214

Magnetic-inertial measurement units (MIMUs) are becoming more prevalent in sports biomechanics and may be a viable tool to evaluate kinematic parameters. This study examined the accuracy of a MIMU to estimate orientation angles under static conditions and dynamically from a squash racket during a forehand drive shot. A MIMU was mounted onto a goniometer and moved through 0–90°, with static data collected at 10° increments during 10 repetitions of all three axes. Typical error analyses showed the MIMU to be very reliable (TE ≤ 0.03°). MIMU accuracy was determined via intraclass correlation coefficients (ICC) (r > 0.999, p < 0.001). An ordinary least products regression showed no proportional bias and minimal fixed bias for all axes. Dynamic accuracy was assessed by comparing MIMU and optical motion capture data of squash racket swing kinematics. A MIMU was fixed onto a racket and 10 participants each hit 10 forehand shots. Mean orientation angle error at ball impact was <0.50° and ICC showed very high correlations (r ≥ 0.988, p < 0.001) for all orientations. Swing phase root mean squared errors were ≤2.20°. These results indicate that a MIMU could be used to accurately and reliably estimate selected racket swing kinematics.  相似文献   

Bayesian reasoning in avalanche terrain: a theoretical investigation     

Philip A. Ebert 《Journal of Adventure Education & Outdoor Learning》2019,19(1):84-95

In this article, I explore a Bayesian approach to avalanche decision-making. I motivate this perspective by highlighting a version of the base-rate fallacy and show that a similar pattern applies to decision-making in avalanche-terrain. I then draw out three theoretical lessons from adopting a Bayesian approach and discuss these lessons critically. Lastly, I highlight a number of challenges for avalanche educators when incorporating the Bayesian perspective in their curriculum.  相似文献   

Whose curriculum is it anyway? Stakeholder salience in the context of Degree Apprenticeships          下载免费PDF全文

Philip Powell  Anita Walsh 《Higher Education Quarterly》2018,72(2):90-106

A Degree Apprenticeship model has recently been introduced into the United Kingdom (UK) Higher Education system as part of wider changes to vocational training. The system has experienced numerous rapid changes in regulation and funding, and it is now little understood by many stakeholders. Distinguishing different phases in UK Higher Education, and using a salience model as a lens for analysis, this article identifies and examines stakeholders with regards to their influence on the Higher Education curriculum. The new Degree Apprenticeship model is funded by an employer payroll levy and it requires Higher Education institutions to deliver training to specific standards. This research explores the implications of the model for the Higher Education curriculum, concluding that the direct involvement of employers in the design and delivery of vocational Higher Education introduces untried elements into UK Higher Education on the assumption that the funding requirement will lead to a change in employer behaviour. This, coupled with the opening of Higher Education provision to private providers, transfers power over the curriculum to those with potentially no commitment to wider public values, and may offer a threat to the international standing of UK Higher Education. This article contributes to research in understanding how Higher Education systems respond to, and actors cope with, imposed change.  相似文献   

The Program for Cooperative Cataloging’s Transformative Role as a Leader of Change     

Philip E. Schreur 《Cataloging & classification quarterly》2020,58(3-4):397-402

Abstract

The transformation of library metadata encoded in MARC to linked data will enable libraries to participate in the Semantic Web. This transformation, however, will be an iterative development dependent upon community-based decisions. The PCC, as a community-based organization, is ideally positioned to lead this transformation. As PCC guides this transition, three broad areas must be resolved: the conversion of legacy data to linked data, the use of identifiers to support controlled headings, and the transformation of current workflows to linked-data counterparts. By embracing the Web as a community, PCC can confirm its relevance in a complex web of global data.  相似文献   

Mapping continuity and change in the intellectual structure of the knowledge base on problem-based learning, 1974–2019: A systematic review     

Philip Hallinger 《British Educational Research Journal》2020,46(6):1423-1444

Problem-based learning (PBL) emerged during the 1970s in response to demands for active learning methods capable of developing transferable knowledge and skills in the training of doctors. Over succeeding decades, PBL was gradually adopted in other fields of education. This systematic review aimed to identify key streams of theory and empirical research that have emerged over time in PBL research and practice. The review sourced 12,036 Scopus-indexed documents published between 1974 and 2019. Science mapping was used to reveal the ‘intellectual structure’ or key research themes that have evolved in this literature over the past 45 years. The science mapping tool used in this review was author co-citation analysis conducted in VOSviewer software. Author co-citation analysis identified three schools of thought that together describe the intellectual structure of the PBL knowledge base: Design of PBL Curriculum and Instruction; PBL Effectiveness; Theory and Practice in Active Learning. In addition to portraying the intellectual structure of the literature as a whole, the review also conducted longitudinal analyses aimed at highlighting structural changes in this field over time. These analyses found that although the size and impact of schools of thought associated with Design of PBL Curriculum and Instruction and PBL Effectiveness increased over time, they remained stable in terms of theoretical foci. However, the Active Learning school evolved from a small school of authors associated with Cognitive Learning Theories prior to 2000 into the largest school of thought during the most recent decades. These findings both reaffirm the theoretical underpinnings of the PBL knowledge base and highlight its increasing integration with other forms of active learning.  相似文献   

The impact of student misconceptions on student persistence in a MOOC     

Chen Chen  Gerhard Sonnert  Philip M. Sadler  Dimitar Sasselov  Colin Fredericks 《科学教学研究杂志》2020,57(6):879-910

Massive Online Open Courses (MOOCs) provide opportunities to learn a vast range of subjects. Because MOOCs are open to anyone with computer access and rarely have prerequisite requirements, the range of student backgrounds can be far more varied than in conventional classroom-based courses. Prior studies have shown that misconceptions have a huge impact on students' learning performance; however, no study has empirically examined the relationship between misconceptions and learning persistence. This study of 12,913 MOOC-takers examines how students' misconceptions about the upcoming course material affect course completion. Using a survival analysis approach, we found that, controlling for the score in a pre-course test, students holding more misconceptions had a higher dropout rate at the start of the course, an effect that diminished over time. Other student variables were found to have a positive impact on survival that persisted throughout the entire course: U.S. location, higher age, an intention to complete, better English skills, prior familiarity with the subject, motivation to earn a certificate, and score and time spent on the previous problem set (homework). By contrast, student gender, education level, number of previous MOOCs completed, and motivation to participate in online discussion forums did not affect survival.  相似文献   

The Efficacy of Preschool Developmental Indicators as a Screen for Early Primary School-Based Literacy Interventions     

Philip J. Schluter  Richard Audas  Jesse Kokaua  Brigid McNeill  Barry Taylor  Barry Milne  Gail Gillon 《Child development》2020,91(1):e59-e76

Literacy success lays the foundation for children's later educational, health, and well-being outcomes. Thus, early identification of literacy need is vital. Using data from New Zealand's national preschool health screening program for fiscal years 2010/2011–2014/2015, demographic and health variables from 255,090 children aged 4 years were related to whether they received a literacy intervention in early primary school. Overall, 20,652 (8.1%) children received an intervention. Time-to-event analysis revealed that all considered variables were significantly related to literacy intervention (all p < .01), but the full model lacked reasonable predictive power for population screening purposes (Harrell's c-statistic = .624; 95% CI [.618, .629]). Including more direct literacy measures in the national screening program is likely needed for improvement.  相似文献   

Interruptions     

Virginia E. Young 《College & Undergraduate Libraries》2014,21(2):239-240

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