Cycling on rollers: influence of tyre pressure and cross section on power requirements     

Reiser R  Watt J  Peterson M 《Sports biomechanics / International Society of Biomechanics in Sports》2003,2(2):237-249

The resistance against a cyclist while riding on rollers is due mainly to rolling resistance produced by the deformation of the tyre as it rolls against small diameter drums. Resistance is then combined with wheel speed to set power output. The effect of tyre pressure and cross-section on power was investigated by systematically altering the pressure (552 kPa, 690 kPa, and 827 KPa) in a 20c, 23c, 25c, and 28c tyre of the same design while riding at a wheel speed of 45 kph. Average power over 1 minute was measured with a Power Tap Hub (Tune Corporation, Cambridge, Massachusetts, USA) on five occasions. Statistical significance was evaluated at p < 0.05. Power requirements increased significantly with each reduction in tyre pressure for all tyres and pressures except the 25c between 690 and 827 kPa. The 20c tyre required significantly more power from the cyclist at each tested tyre pressure when compared to the other tyres (which were not different from each other). The differences in resistance from tyre size were not observed when ridden on the road. Additionally, a slightly different tyre design from the same manufacturer responded similarly in the 20c, but was significantly different in the 23c size. It was also observed that power requirements increased significantly when both the wheels were ridden on the rollers as compared to just the rear wheel. These results indicate that the power requirements may be significantly altered by the cyclist by adjusting tyre pressure, tyre cross-section size, tyre type, and with the number of wheels contacting the rollers. However, the magnitude of these power requirements may not be suitable for intense workouts of trained cyclists.  相似文献   

Extending Big‐Five theory into childhood: A preliminary investigation into the relationship between Big‐Five personality traits and behavior problems in children     

David J. Ehrler  J. Gary Evans  Ron L. McGhee 《Psychology in the schools》1999,36(6):451-458

An investigation was conducted to link Big‐Five personality traits with behavior problems identified in childhood. Eighty‐six children ranging in age from 9 to 13 were rated by their respective classroom teacher using an experimental ratings instrument developed to measure Big‐Five personality constructs and behavior concurrently. Big‐Five Personality and Behavior Problem scales were correlated. Results show distinct patterns of behavior problems associated with various personality characteristics. Children with low scores in Agreeableness and Conscientiousness exhibit social problems, conduct problems, attention deficits, and hyperactivity. Children with low scores on the scale, Openness to Experience, exhibit problems in social behavior, conduct, and attention. The Neuroticism trait was associated with anxiety and depression. Potential implication for clinical practice and future research study was provided. These preliminary data indicate that identifying Big‐Five personality trait patterns may be a useful dimension of assessment for understanding underlying motives and predispositions associated with children's problem behavior. © 1999 John Wiley & Sons, Inc.  相似文献   

Psychometric and edumetric validity of dimensions of geomorphological knowledge which are tapped by concept mapping     

Ron Hoz  Dan Bowman  Tova Chacham 《科学教学研究杂志》1997,34(9):925-947

The validity of several dimensions of knowledge which were inferred from concept maps was assessed for its psychometric and edumetric aspects. Data were collected from 14 students who enrolled in the university first-year introductory geomorphology course and in its prerequisite introductory geology course. They took an objective geomorphology test, the tree construction task, and the Standardized Concept Structuring Analysis Technique (SConSAT) version of concept mapping. Comparisons among these dimensions of knowledge before and after the geomorphology course yielded convergent evidence. For the psychometric perspective, the SConSAT version of concept mapping and tree construction had similar knowledge structure representations, and the cognitive map correctness was moderately positively correlated with the objective test but not with the geomorphology course test. For the edumetric perspective, the majority of the dimensions of knowledge structures from the SConSAT showed large improvements following the geomorphology course. This evidence shows that the knowledge structure dimensions have moderate to good construct validity which warrant their widespread use for evaluating learning outcomes in both experimental and classroom settings. © 1997 John Wiley & Sons, Inc. J Res Sci Teach 34: 925–947, 1997.  相似文献   

Eliminating common misconceptions about behavioral psychology: One step toward increased academic productivity     

Daniel H. Tingstrom  Ron Edwards 《Psychology in the schools》1989,26(2):194-202

The present article emphasizes the compatibility of behavioral psychology and behavioral interventions in the classroom with today's demands for educational excellence and accountability by classroom teachers. Teacher resistance to the implementation of behavioral interventions is discussed with respect to various misconceptions involving perceived practical obstacles. Misconceptions are corrected and practical suggestions for implementing behavioral interventions are provided. The use of behavioral interventions to achieve accountability and improved student performance is emphasized.  相似文献   

The AAMD ABS-SE,Part Two: Criterion-related validity in a behavior-disordered sample     

Gail M. Cheramie  Ron P. Edwards 《Psychology in the schools》1990,27(3):186-195

The purpose of this research was to determine the diagnostic validity of Part Two of the AAMD Adaptive Behavior Scale-School Edition (ABS-SE) for the classification of behavior-disordered (BD) children. The sample consisted of 66 elementary school students ranging in age from 7-0 through 12-11. There were three groups of subjects: (a) children classified BD; (b) children referred for behavior problems, but not classified; and (c) children in regular classrooms, neither referred nor classified. Teachers completed Part Two of the ABS-SE for all subjects. Validity was investigated for both domain and factor scores, with discriminant analyses yielding significant classification results. Using the domain scores generated by the stepwise discriminant analysis, the overall rate of correct classification was 71.21%; using factor scores, the level of correct classification increased to 77.27%.  相似文献   

A Comparison of Professional Development Models for Teachers of Primary Mathematics and Science     

Russell Tytler  Ron Smith  Peter Grover  Sally Brown 《Asia-Pacific Journal of Teacher Education》1999,27(3):193-214

The authors have been involved in two substantial Australian teacher professional development projects, with the Mathematical Association of Victoria and with the Science Teachers’ Association of Victoria, which focused, respectively, on a whole‐school professional development and an extended workshop programme. The research described in this paper explores the experiences of participants in these two programmes, in order to identify the advantages and limitations of each type of professional development model in supporting teacher development, and the different needs of teachers in relation to mathematics and science. The findings from a questionnaire, supported by participant interviews, show a range of differences in experience and outcomes due to programme style and subject area. These are used to suggest a developmental framework for conceptualizing teacher professional development needs.  相似文献   

机械加工自动线模拟程序设计     

丁红娟  朱阿键 《常熟理工学院学报》1999,13(2):105-107

用一台ＩＰＣ机帝现一条模拟加工自动线的自动控制及模拟显示,采用了两个光电开关和十二个接近开关以及一个软按钮作为输入量,软件设计时采用了四个程序模块分别对输送带电机及工位１,工位２,工位３的电机进行控制。  相似文献   

Contractual school psychological services: Prevalence and practices     

Michael B. Brown  Ron L. Gibson  Larry M. Bolen 《Psychology in the schools》2000,37(4):333-337

This study investigated the prevalence and practices of contract school psychological services in public schools. A survey was sent to all 121 school districts in a southeastern state, with 111 surveys completed for a response rate of 92%. Results indicated that most school districts did not believe that contracting is cost effective. The primary service provided by contractual service providers was triennial reevaluations. The administrator most often charged with the hiring and supervision of contract providers was not a school psychologist. The credential most often required of a contracting psychologist was a State Board of Psychology license, with only a few requiring documentation of relevant coursework or experience. The results of this study indicated that the most pressing concern for the profession of school psychology regarding contractual services is ensuring that contract services are provided and monitored according to appropriate standards of practice. © 2000 John Wiley & Sons, Inc.  相似文献   

We Will Shoot Back: Armed Resistance in the Mississippi Freedom Movement Akinyele Omowale Umoja. New York: New York University Press, 2013.     

Ron Briley 《Journal of American culture (Malden, Mass. : 2003)》2014,37(2):267-268

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A social neuroscience perspective on physical activity     

Hall PA  Elias LJ  Fong GT  Harrison AH  Borowsky R  Sarty GE 《运动与训练心理学杂志》2008,30(4):432-449

The objective of this investigation was to examine the cognitive characteristics of individuals who demonstrate successful and unsuccessful self-regulation of physical activity behavior. In Study 1, participants articulated 1-week intentions for physical activity and wore a triaxial accelerometer over the subsequent 7 days. Among those who were motivated to increase their physical activity, those who were most and least successful were administered an IQ test. In Study 2, a second sample of participants completed the same protocol and a smaller subset of matched participants attended a functional imaging (fMRI) session. In Study 1, successful self-regulators (SSRs) scored significantly higher than unsuccessful self-regulators (USRs) on a test of general cognitive ability, and this difference could not be accounted for by favorability of attitudes toward physical activity or conscientiousness. In Study 2, the IQ effect was replicated, with SSRs showing a full standard deviation advantage over USRs. In the imaging protocol, USRs showed heavier recruitment of cognitive resources relative to SSRs in the anterior cingulate and orbitofrontal cortex during performance of a Stroop task; SSRs showed heavier recruitment in the right dorsolateral prefrontal cortex.  相似文献