The kinematic differences between off-spin and leg-spin bowling in cricket

Spin bowling is generally coached using a standard technical framework, but this practice has not been based upon a comparative biomechanical analysis of leg-spin and off-spin bowling. This study analysed the three-dimensional (3D) kinematics of 23 off-spin and 20 leg-spin bowlers using a Cortex motion analysis system to identify how aspects of the respective techniques differed. A multivariate ANOVA found that certain data tended to validate some of the stated differences in the coaching literature. Off-spin bowlers had a significantly shorter stride length (p = 0.006) and spin rate (p = 0.001), but a greater release height than leg-spinners (p = 0.007). In addition, a number of other kinematic differences were identified that were not previously documented in coaching literature. These included a larger rear knee flexion (p = 0.007), faster approach speed (p < 0.001), and flexing elbow action during the arm acceleration compared with an extension action used by most of the off-spin bowlers. Off-spin and leg-spin bowlers also deviated from the standard coaching model for the shoulder alignment, front knee angle at release, and forearm mechanics. This study suggests that off-spin and leg-spin are distinct bowling techniques, supporting the development of two different coaching models in spin bowling.     

Ground reaction forces of Olympic and World Championship race walkers

Race walking is an Olympic event where no visible loss of contact should occur and the knee must be straightened until midstance. The purpose of this study was to analyse ground reaction forces of world-class race walkers and associate them with key spatiotemporal variables. Nineteen athletes race walked along an indoor track and made contact with two force plates (1000 Hz) while being filmed using high-speed videography (100 Hz). Race walking speed was correlated with flight time (r = .46, p = .049) and flight distance (r = .69, p = .001). The knee's movement from hyperextension to flexion during late stance meant the vertical push-off force that followed midstance was smaller than the earlier loading peak (p < .001), resulting in a flattened profile. Athletes with narrower stride widths experienced reduced peak braking forces (r = .49, p = .046), peak propulsive forces (r = .54, p = .027), peak medial forces (r = .63, p = .007) and peak vertical push-off forces (r = .60, p = .011). Lower fluctuations in speed during stance were associated with higher stride frequencies (r = .69, p = .001), and highlighted the importance of avoiding too much braking in early stance. The flattened trajectory and consequential decrease in vertical propulsion might help the race walker avoid visible loss of contact (although non-visible flight times were useful in increasing stride length), while a narrow stride width was important in reducing peak forces in all three directions and could improve movement efficiency.     

Voices of teacher candidates of color on white race evasion: ‘I worried about my safety!’

Abstract

This qualitative study investigated the negative impacts minority teacher candidates receive from white teacher candidates in a required multicultural education class. The findings reveal that four teacher candidates of color had difficulty positioning themselves among the overwhelming silencing power of whiteness in the class. The white students were tactful at evading power and race and flattening the existing hierarchical power relations through the discourses of colorblindness and by preying on the minority instructor. Their understanding of diversity was also shallow. On the other hand, the teacher candidates of color were afraid that they might be labeled as the ones who spoke up against the white students and fearful of the possibility of retaliation and ostracism from the white peers. It seems that the teacher education program’s structure allowed the white candidates to impose strong negative peer pressure on the teacher candidates of color.     

Hybrid ants-like search algorithms for P2P media streaming distribution in ad hoc networks

Media streaming delivery in wireless ad hoc networks is challenging due to the stringent resource restrictions,po-tential high loss rate and the decentralized architecture. To support long and high-quality streams,one viable approach is that a media stream is partitioned into segments,and then the segments are replicated in a network and served in a peer-to-peer(P2P) fashion. However,the searching strategy for segments is one key problem with the approach. This paper proposes a hybrid ants-like search algorithm(HASA) for P2P media streaming distribution in ad hoc networks. It takes the advantages of random walks and ants-like algorithms for searching in unstructured P2P networks,such as low transmitting latency,less jitter times,and low unnecessary traffic. We quantify the performance of our scheme in terms of response time,jitter times,and network messages for media streaming distribution. Simulation results showed that it can effectively improve the search efficiency for P2P media streaming distribution in ad hoc networks.     

大学物理辅导艺术浅析

基于对装甲兵工程学院物理辅导的问卷调查，分析目前存在于该教学环节中的几个误区，阐述了辅导中教与学的关系，对辅导技巧与答疑艺术进行了一些探索。     

An empirical review of anonymity effects in peer assessment,peer feedback,peer review,peer evaluation and peer grading

Abstract

Peer assessment has proven to have positive learning outcomes. Importantly, peer assessment is a social process and some claim that the use of anonymity might have advantages. However, the findings have not always been in the same direction. Our aims were: (a) to review the effects of using anonymity in peer assessment on performance, peer feedback content, peer grading accuracy, social effects and students’ perspective on peer assessment; and (b) to investigate the effects of four moderating variables (educational level, peer grading, assessment aids, direction of anonymity) in relation to anonymity. A literature search was conducted including five different terms related to peer assessment (e.g., peer feedback) and anonymity. Fourteen studies that used a control group or a within group design were found. The narrative review revealed that anonymous peer assessment seems to provide advantages for students’ perceptions about the learning value of peer assessment, delivering more critical peer feedback, increased self-perceived social effects, a slight tendency for more performance, especially in higher education and with less peer assessment aids. Some conclusions are that: (a) when implementing anonymity in peer assessment the instructional context and goals need to be considered, (b) existent empirical research is still limited, and (c) future research should employ stronger and more complex research designs.     

高校学生思想教育与心理辅导协调机制探微

面对新形势下的新情况、新挑战,高校学生思想教育与心理辅导必须加强协调、形成合力。高校学生思想教育与心理辅导具有过程要素的趋同性、教育功能的互补性、工作方法的交互性,为建立二者之间的协调机制提供了内在条件和可能。树立“合力”意识、建立双向通报制度、实行工作对象“转介”、开展业务交叉培训是建立协调机制的基本途径。     

Paired peer learning through engineering education outreach

ABSTRACT

Undergraduate education incorporating active learning and vicarious experience through education outreach presents a critical opportunity to influence future engineering teaching and practice capabilities. Engineering education outreach activities have been shown to have multiple benefits; increasing interest and engagement with science and engineering for school children, providing teachers with expert contributions to engineering subject knowledge, and developing professional generic skills for engineers such as communication and teamwork. This pilot intervention paired 10 pre-service teachers and 11 student engineers to enact engineering outreach in primary schools, reaching 269 children. A longitudinal mixed methods design was employed to measure change in attitudes and Education Outreach Self-Efficacy in student engineers; alongside attitudes, Teaching Engineering Self-Efficacy and Engineering Subject Knowledge Confidence in pre-service teachers. Highly significant improvements were noted in the pre-service teachers’ confidence and self-efficacy, while both the teachers and engineers qualitatively described benefits arising from the paired peer mentor model.     

Peer facilitated writing groups: a programmatic approach to doctoral student writing

Very few empirical studies have investigated programmes in which doctoral students act as peer facilitators in faculty writing groups. We report on the development of a centrally delivered doctoral student writing programme in which twenty student participants were mentored and provided with the resources to initiate their own faculty-based doctoral writing groups. ‘Legitimate peripheral participation’ was used as a conceptual lens to interpret the data collected during the establishment and evaluation of the programme. All student participants in the preparatory training course, which was developed in consultation with postgraduate students and research supervisors, went on to become doctoral writing peer facilitators of peer writing groups. Insights from seven of these showed how a well-structured and supportive programme harnessed the benefits of peer learning by bringing personal rewards to participants and building institutional capacity around doctoral research writing literacies.     

基于博客的大学英语写作教学同学互评模式探讨

博客(Blog)是一种新型的网络沟通方式和知识管理工具。通过建立班级博客、博客群组、班级作品集和写作学习资源库等途径构建基于博客的英语写作教学同学互评模式,将有效地利用博客这一新型的教学平台,改善传统的写作教学模式,让同学参与到作文的评改活动中,促进学生写作水平的提高。