Ball launch conditions for skilled golfers using drivers of different lengths in an indoor testing facility

The displacement of the golf ball struck by a driving club is affected by several player characteristics and equipment parameters and their interrelationships. Some modelling and simulation studies have shown a relationship between shaft length and clubhead speed, supported by a few experimental studies. The aim of the present study was to examine the relationship between driver length and ball launch conditions in an indoor test facility using a ball launch monitor. Nine males considered to be skilled golfers participated in the study. Four driving clubs of total length 117, 119, 124, and 132 cm were assembled from commercially available components and were used to strike golf shots while initial ball velocity, backspin rate, and launch angles were measured. Statistical analysis identified a significant difference in initial launch speed due to club length, a significant difference between participants, but no difference between the trials for a given golfer. A positive trend was noted between backspin and launch angle for all four clubs, and significant inverse associations between initial launch speed and backspin rate and launch angle. However, the combined launch conditions associated with increasing length were not considered optimal, with uncontrolled swingweight and moment of inertia effects considered to be limiting factors.     

Anthropometric dimensions of male powerlifters of varying body mass

In this study, we examined the anthropometric dimensions of powerlifters across various body mass (competitive bodyweight) categories. Fifty-four male Oceania competitive powerlifters (9 lightweight, 30 middleweight, and 15 heavyweight) were recruited from one international and two national powerlifting competitions held in New Zealand. Powerlifters were assessed for 37 anthropometric dimensions by ISAK (International Society for the Advancement of Kinanthropometry) level II and III accredited anthropometrists. The powerlifters were highly mesomorphic and had large girths and bony breadths, both in absolute units and when expressed as Z(p)-scores compared through the Phantom (Ross & Wilson, 1974). These anthropometric characteristics were more pronounced in heavyweights, who were significantly heavier, had greater muscle and fat mass, were more endo-mesomorphic, and had larger girths and bony breadths than the lighter lifters. Although middleweight and heavyweight lifters typically had longer segment lengths than the lightweights, all three groups had similar Zp-scores for the segment lengths, indicating similar segment length proportions. While population comparisons would be required to identify any connection between specific anthropometric dimensions that confer a competitive advantage to the expression of maximal strength, anthropometric profiling may prove useful for talent identification and for the assessment of training progression in powerlifting.     

Trial-by-trial analysis or averaging: implications for electromyographic models of rapid limb control

The control of human limb movement has been the focus of research for more than a century. A major issue to emerge from this work is the manner in which the central nervous system regulates electromyographic (EMG) activity to produce movements that differ in distance, velocity, and movement time. However the different methods of analysis often used to analyze EMG data could result in different kinematic-EMG relationships. In this study, participants performed an elbow flexion task to one of five distance goals (between 5 degrees and 50 degrees) using three movement speeds. EMG data from the right elbow flexors were compared using a trial-by-trial analysis and one based on averaged data. Averaging across trials underestimated biceps EMG amplitude at all movement distances and speeds compared to a trial-by-trial analysis. Averaging overestimated EMG burst duration compared to the trial-by-trial analysis. Peak agonist EMG amplitude was positively related to distance and inversely related to movement time. Agonist EMG duration was constant for movement distances less than 30 degrees but increased in the 50 degrees condition. The results support the view that peak EMG amplitude and duration can be controlled independently, but EMG duration changes only for longer distance movements when additional force is required.     

Effect of a pedometer-based intervention on daily step counts of community-dwelling older adults

This study investigated the effect of a 12-week pedometer-based intervention on daily step counts of 147 older adults randomly assigned to an intervention or wait-list control group (M age = 72.9 years, SD = 8.8). The intervention group significantly increased their daily step counts after 12 weeks (M=639, SD=2239) and continued to significantly increase during a 12-week maintenance period (M=680, SD=1721). The control group exhibited no change during the control period (M = -393, SD=2050) but had a significant increase in daily step counts (M=1580, SD=2305) when enrolled in the intervention. The pedometer-based intervention was effective in increasing participants' daily step counts.     

论环境工程专业实验教学中实验室助管的协同作用

论述了环境工程专业实验室的现状,指出实验室助管的出现从很大程度上缓解了实验室人员配置不足的问题,具有重要意义。从实验室助管工作的范围、作用意义、存在的问题以及如何更好地发挥其重要作用等几个方面进行着重探讨。     

Simplified method of designing FIR filter with controllable center frequency

A novel simplified method is presented to design FIR filter with controllable center frequency. The properties of transfer curves for all-phase filters are illustrated under 3 windowing conditions. By combining single-window all-phase filter design steps and double phase-shift combination, a series of design formulas for point-pass filter, notch filter, band-pass filter and band-stop filter are derived, thus the design computation complexity is greatly reduced. Experiments prove that the center frequency of all the filters can be accurately specified at arbitrary position by adjusting frequency parameters m and λ.     

一个新的声压级测试实验方案

通过对声压级的若干概念讨论,阐述了声压级的各种计量值以及A计权与线性计权之间的关系,根据讨论设计了一个新的声压级测试实验方案。该方案分为:①从声压级大小与波形的关系体现声压级的有效值、峰值之间的区别和联系;②利用滤波器改变待测信号的幅度频率特性,分别测试其A计权声压级、线性计权声压级以及幅度频率特性。根据声压级的计算公式,利用测试得到线性计权声压级和信号的幅度频率特性计算得A计权声压级,并与测试值对比,结果大致相符。通过实验体现了声压级的丰富内涵,避免了传统声压级测试实验方案的内容单一性。     

The impacts of an early mathematics curriculum on oral language and literacy

Competence in early mathematics is crucial for later school success. Although research indicates that early mathematics curricula improve children's mathematics skill, such curricula's impacts on oral language and early literacy skills are not known. This project is the first to investigate the effects of an intensive pre-kindergarten mathematics curriculum, Building Blocks, on the oral language and letter recognition of children participating in a large-scale cluster randomized trial project. Results showed no evidence that children who were taught mathematics using the curriculum performed differently than control children who received the typical district mathematics instruction on measures of letter recognition, and on two of the oral language (story retell) subtests, sentence length and inferential reasoning (emotive content). However, children in the Building Blocks group outperformed children in the control group on four oral language subtests: ability to recall key words, use of complex utterances, willingness to reproduce narratives independently, and inferential reasoning (practical content).