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31.
The purpose of this study was to assess the effect of periodized resistance training on accelerative sprint performance. Sixteen physically active men participated in a randomized controlled study. An experimental group (n = 10) completed an 8-week periodized resistance training intervention, while a control group (n = 6) did not train. Pre- and post-training measures of 20-m straight-line sprint time, including a 10-m split, maximum strength, and explosive strength, were recorded. Flight time, stance time, stride length, and stride frequency were quantified from digitized video recordings of the first three strides of the 20-m sprint. Resistance training resulted in significant increases in maximum strength (parallel back squat: 19%) and explosive strength (6-10%). However, both groups increased 0-10 m sprint times (experimental group = 6%; control group = 3%) while 10-20m times were reduced (experimental group = 7%; control group = 4%), highlighting the mechanical differences between the distinct sprint phases. The change during the 0-10m interval was accompanied by a reduction in stride frequency during the first three strides. Strength coaches should be aware that the potential benefits of increased muscular strength during short sprints are likely to be affected by mechanical specificity and that improvements in sprinting performance may not occur immediately after a period of resistance training.  相似文献   
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Abstract from the report of the International Conference on Education (33rd Session) of the International Bureau of Education. It deals with (i) the role of higher education institutions in national development, (ii) improving and sustaining the competence of educators and (iii) managing the system of education.  相似文献   
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The expanding universe is described in terms of the known forces of classical physics. It is shown that great clouds of stars are non-conservative systems and that radiation reaction forces play a part in guiding stellar motions. The forces are of importance in unsymmetrical stars and evidence is collected to show that perhaps all stars are possessed of deep seated thermal asymmetries. The forces continually act to increase the mean velocity of the stars and the galaxy is calculated to expand at a rate which closely approximates the observed rate of expansion. From a relation connecting the mean velocity of the stars and their age, it is deduced from the observed motions that the age of the galaxy is about 1010 years. The deduced rate of expansion of the galaxy agrees well with the observational data and is identical in form and numerical constant with Hubble's relation connecting the velocity of recession and distances of nebulæ.Because of the relative size and spacing of the extra galactic nebulæ and the short time scale it is supposed that the nebulae were formed by fission from a parent-super nebula and this resulted in thermal asymmetries which brought the newly considered forces into action.The resulting expansion was produced by slow evolutionary radiation processes which bear no direct relation to the properties of space or atomic constants.The calculations suggest that in describing the motions of typical stars over long periods of time, radiation reaction forces are as important as the classical gravitational forces.  相似文献   
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This paper is in the tradition of social analysis aimed at creatingframeworks to join mass media and public opinion processes (e.g.Clarke and Evans, 1983; Gamson, 1975; Gitlin, 1980; Hall, 1977;Iyengar and Kinder, 1987; Lang and Lang, 1968, 1983; Lippman,1922; Mollotch and Lester, 1974; Noelle-Neuman, 1974; Paletzand Entman, 1981; Shaw and McCombs, 1977; Turner and Paz, 1986).After a brief review of media system dependency (MSD) theory,we illustrate how it may apply to public opinion processes thatentail contested issue ‘value-frames’ (Ball-Rokeachand Rokeach, 1987). In such cases, the media system is directlyimplicated in the negotiation of legitimacy of opposing positionson an issue. Our illustrative case is the abortion issue asit has been played out in the United States over recent decades(Luker, 1984). We focus upon the respective capacities of pro-and anti-abortion movements to control the value-frame of mediacoverage of the issue (Guthrie, 1989). A value-frame may beconceived as ‘... the main substantive theme of a moralityplay’ (Ball-Rokeach and Tallman, 1979) wherein the distinctionbetween ‘good’ and ‘bad’ hangs in thebalance; in this case, between positions on abortion. We suggestthat change in the value-frame of media coverage and publicdiscourse may be understood, at least in part, as an outcomeof change in contestants' MSD relations.  相似文献   
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The study investigated how well report card grades communicate to students and parents that state educational standards are being met, standards that are objectively measured by infrequently administered mandated assessments. Data sources were report card grades and external assessment scores for 2006–09 for Ontario Canada. The information that parents and students received about student performance from report cards and external assessments were similar (r s  = .47) to the r = .40–.60 range previously reported. Teachers assigned higher grades than external assessments warranted, even after a major source of construct irrelevant variance in report card grades (teacher ratings on multiple scales measuring student effort and school commitment) was controlled. The relationship of grades to assessment scores was robust across genders, school district types (Public versus Catholic) and language (English and French). Agreement of assessments was higher for grade 6 than for grade 3 and for Writing than for Reading or Mathematics. Report cards provided information about students’ future achievement that was accurate and delivered up to 2 years prior to the administration of external assessments. Seventy to 80% of students who reached the provincial achievement standard on one or both prior report cards were successful on the subsequent external assessment, compared to 30–50% of students who failed to meet the report card standard at least once.  相似文献   
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