The reliability of accelerometry to measure weightlifting performance     

Kimitake Sato  William A. Sands  Michael H. Stone 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(4):524-531

The purposes of the study were to track weightlifters' barbell acceleration with a portable accelerometer over three training sessions to examine test–retest reliability and to compare peak barbell acceleration at different training intensities. Twelve nationally ranked weightlifters volunteered for this study. The portable accelerometer was attached to the right side of the barbell to measure barbell resultant acceleration during the snatch lift at a sampling frequency of 100 Hz. The data were collected over three training sessions at intensity levels of 80%, 85%, and 90% of one repetition maximum. The data were analyzed using intra-class correlation coefficients (ICCs) for the three training sessions and one-way repeated measure ANOVA to compare the difference in peak barbell acceleration at three intensities. Results showed that the device was highly reliable with an ICC of 0.88 and 95% confidence interval of 0.81–0.93. There were significant differences in peak barbell acceleration at various lifting intensities, indicating a decline of the acceleration as the mass of the barbell became heavier. The portable accelerometer seems useful in measuring barbell acceleration data, which can be analyzed in future studies to monitor a weightlifter's performance in a practical setting instead of testing at a laboratory.  相似文献   

Muscle activation characteristics of tumbling take-offs     

Jeni R. Mcneal  William A. Sands  Barry B. Shultz 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(3):375-390

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Don't throw it away     

Dorothy Sands Arthur 《Early Childhood Education Journal》1981,9(2):31-32

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Books for the children     

Dorothy S. Strickland  Barbara Sands Worth 《Early Childhood Education Journal》1981,9(1):34-35

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Anthropometric and physical abilities profiles: US National Skeleton Team     

Sands WA  Smith LS  Kivi DM  McNeal JR  Dorman JC  Stone MH  Cormie P 《Sports biomechanics / International Society of Biomechanics in Sports》2005,4(2):197-214

The aim of this study was to characterize sprint ability, anthropometry, and lower extremity power in the US National Team Skeleton athletes. Fourteen athletes (male n = 7; mean +/- SD: height 1.794 +/- 0.063 m, body mass 81.2 +/- 3.7 kg, age 26.9 +/- 4.1 years; female n = 7; 1.642 +/- 0.055 m, 60.1 +/- 5.9 kg, 27.3 +/- 6.9 years) volunteered to participate. Sprinting ability was measured over multiple intervals using custom infrared timing gates in both an upright and a crouched sprint. The crouched sprint was performed while pushing a wheeled-simulated skeleton sled on rails on an outdoor skeleton and bobsleigh start track. Crouched skeleton sprint starts were able to achieve about 70% to 85% of the upright sprint times. The mean somatotype ratings for females were: 3.5-3.5-2.1, and males: 3.6-4.9-1.9. Lower extremity strength and power were measured via vertical jumps on a portable force platform using squat and countermovement jumps, and jumps with added mass. Jump height, power, rate offorce development and peak force were determined from force-time data. Lower extremity strength and power were strongly correlated with both upright and crouched sprint times. The results indicated that these athletes are strong sprinters with varying body structures, mostly mesomorphic, and that stronger and more powerful athletes tend to be better starters.  相似文献   

The development of argument skills     

Kuhn D  Udell W 《Child development》2003,74(5):1245-1260

This work sought to obtain experimental evidence to corroborate cross-sectional patterns of development in argument skills and to evaluate the effectiveness of an intervention designed to foster development of these skills in academically at-risk 13- to 14-year-olds. Students participated in 16 sessions of a collaborative, goal-based activity providing dense exercise of argumentive thinking. One condition included peer dialogues; another did not. The former was the more effective, although both groups progressed. Participants showed increased frequency of usage of powerful argumentive discourse strategies, such as counterargument, and decreased frequency of less effective strategies. Quality of individual arguments (for or against a claim) also improved, supporting the existence of a close relation between these two kinds of argument skills.  相似文献   

Expanding computer science education in schools: understanding teacher experiences and challenges     

Aman Yadav  Sarah Gretter  Susanne Hambrusch  Phil Sands 《Computer Science Education》2016,26(4):235-254

The increased push for teaching computer science (CS) in schools in the United States requires training a large number of new K-12 teachers. The current efforts to increase the number of CS teachers have predominantly focused on training teachers from other content areas. In order to support these beginning CS teachers, we need to better understand their experiences and challenges encountered in the classroom. This study investigated U.S. CS teachers’ perspectives on the demands of teaching computer science and support needed to ensure quality teaching. Results suggested that teachers face a number of challenges, including isolation, lack of adequate computer science background, and limited professional development resources.  相似文献   

Does rational persuasion influence potential consultees?     

Stephen D. Truscott  Robert D. Richardson  Celina Cohen  Alicia Frank  Deanna Palmeri 《Psychology in the schools》2003,40(6):627-640

Success in collaborative school‐based consultation depends on whether teachers implement interventions suggested by consultants. In business literature, Rational Persuasion (RP) has been identified as one potentially effective way to influence consultee perceptions about proposed interventions. RP includes intervention information, why it is important to decide to use the intervention, and potential objections to the intervention with arguments against those objections. The influence of these RP elements on potential school‐based consultees has not been studied. This preliminary analog study investigated whether presenting RP importance and objections for behavioral interventions influenced teachers' ratings of acceptability, effectiveness, and commitment‐to‐implement. Participants included 71 teachers enrolled in graduate education courses. The within‐subject design included three video vignettes of each of three conditions for three different behavioral interventions (total of nine possible videos, three presented to each group). Results suggest that the influence of RP on acceptability, perceived effectiveness, and commitment‐to‐implement ratings was inconsistent. Implications for research and practice are discussed. © 2003 Wiley Periodicals, Inc. Psychol Schs 40: 627–640, 2003.  相似文献   

Using Entrepreneurial Activities as a Means of Survival: Investigating the Processes used by Australian Universities to Diversify their Revenue Streams     

Deanna de?ZilwaEmail author 《Higher Education》2005,50(3):387-411

This study provides a profile of the actions taken by Australian universities to diversify their revenue streams in order to generate more independent (non-government) income. Marginson’s taxonomy of Australian universities is used to catergorise universities and contrast levels of independent income (Marginson and Considine 2000). This study finds that some Australian universities have used isomorphic tactics in their attempts to diversify their revenue streams. Unitechs (Universities of Technology) and New Universities are over-reliant upon income earned from overseas student fees, whilst earning comparatively small amounts of revenue from Royalties, Trademarks and Licences, Consultancy, Contract Research and Investments. This work discusses the dangers inherent in over-reliance on a single type of independent income. It argues that if Australian universities seek to enhance their success competing in global research, staff and student markets then they need to augment efforts to diversify revenue streams with structural and cultural changes, transforming themselves from being rigid hierarchical public bureaucracies to become more flexible network enterprises (Castells 2000).  相似文献   

Interference of delayed matching to sample in pigeons: Effects of interpolation at different periods within a trial and stimulus similarity     

Anthony A. Wright  Peter J. Urcuioli  Stephen F. Sands  Hector C. Santiago 《Learning & behavior》1981,9(4):595-603

Delayed matching-to-sample performance by pigeons was interfered with by displaying a monochromatic annulus around the center (sample) pecking key. The wavelength of the annulus and its point of interpolation within a trial were varied to determine possible differential effects on matching accuracy. Experiment 1 showed that delayed matching was most disrupted when the interference stimulus (570 nm, 630 nm, or achromatic white) appeared during the delay interval of a trial. Little if any disruption occurred when the interference stimulus was present during the sample and choice periods. The spectral relationship between the chromatic interference stimuli (570 and 630 nm) and the sample stimuli (570 and 630 nm) did not consistently influence the degree to which matching accuracy was affected in any interpolation condition. Experiment 2 found a similar pattern of within-trial effects when the interference stimulus was simply a change from a white achromatic annulus to a chromatic one. This finding indicates that illumination changes, such as the popular houselight variation, are not necessary to produce interference in delayed matching to sample. Even with illumination held constant, however, performance was not differentially sensitive to the similarity between interference and sample stimulus wavelengths. It is suggested that other experiments showing similarity effects in interference of delayed matching to sample were conducted in such a way that subjects confused the interfering stimuli with the samples.  相似文献