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31.
Mary A. Anderson Frank Bowles C. O. Taiwo Jan D. Beckmann L. J. Lewis James R. Liesch Godfrey N. Brown H. L. Elvin Shib K. Mitra Richard F. Behrendt Graeme Kemelfield Hugh W. R. Hawes W. A. Dodd A. L. Tibawi 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1971,17(2):220-251
32.
The radial and axial motions of electrons in the betatron are described by means of a potential function of forces. Previously reported conditions of equilibrium, stability and damping of oscillations are derived for the region of parabolic variation of the potential. Extension of the analysis to, non-parabolic regions gives an account of the injection in conventional instruments in better agreement with experiment, particularly in regard to higher voltages of injection.Space charge limitations are discussed with the help of the Laplacian of the potential of forces.By means of an additional radial electric field electrons can be introduced as in the magnetron, without any asymmetry inherent in the conventional betatron circumferential injector. The analysis of the conditions of equilibrium and stability, greatly facilitated in this case by the notion of potential, shows that no substantial improvement in space charge limitations can be expected and that the required variations between the flux linking the electron orbits and the magnetic and electric fields at the orbits are difficult to realize on account of their complexity and narrow tolerances. The X-ray output of a small experimental double yoke instrument was measured by a phototube multiplier viewing an irradiated fluorescent screen and gave evidence of multiple group electron capture. 相似文献
33.
This study assessed the differential contribution of personality to the explanation of variance in achievement in the mother tongue and mathematics at the high school level. The results indicated that personality, as measured by the HSPQ, aided the explication of variance in achievement in the mother tongue significantly, but had little influence on mathematics. Personality contributed as much to the explanation of variance in the mother tongue as did the composite cognitive variable. The influence of personality on achievement in mathematics was shown to be negligible. Some practical implications for the teaching of the first language are drawn. 相似文献
34.
Hoff J 《Journal of sports sciences》2005,23(6):573-582
Elite soccer players spend a substantial amount of time trying to improve physical capacities, including aerobic endurance and strength and the strength derivatives of speed and power. The average oxygen uptake for international soccer teams ranges from 55 to 68 ml.kg-1.min-1 and the half-squat maximal strength from 120 to 180 kg. These values are similar to those found in other team sports. Recently, it has been shown that the heart's stroke volume is the element in the oxygen chain that mainly limits aerobic endurance for athletes. These findings have given rise to more intensive training interventions to secure high stroke volumes, which, in turn, have proved positive in changing both maximal oxygen consumption and soccer performance in terms of distance covered, contacts with the ball and number of sprints in a game. The training employed has consisted of 4x4-min "intervals" running uphill at 90-95% of maximal heart rate interspersed with 3 min jogging at 70% of maximal heart rate to facilitate removal of lactate. Research has revealed that a soccer-specific training routine with the ball might be as effective as plain running. Strength training to produce neural adaptations has been effective in changing not only strength in terms of "one-repetition maximum", but also sprinting velocity and jumping height, in elite soccer players without any change in body mass. The same training has also improved running economy and thus aerobic endurance performance. The training regimen used for a European Champions League team was 4x4 repetitions of half-squats with the emphasis on maximal mobilization of force in the concentric action. 相似文献
35.
Jiří Baláš David Giles Jan Kodejška Michaela Panáčková Simon Fryer 《European Journal of Sport Science》2016,16(7):764-772
This study aimed to (1) evaluate the effect of hand shaking during recovery phases of intermittent testing on the time–force characteristics of performance and muscle oxygenation, and (2) assess inter-individual variability in the time to achieve the target force during intermittent testing in rock climbers. Twenty-two participants undertook three finger flexor endurance tests at 60% of their maximal voluntary contraction until failure. Performances of a sustained contraction and two intermittent contractions, each with different recovery strategies, were analysed by time–force parameters and near-infrared spectroscopy. Recovery with shaking of the forearm beside the body led to a significantly greater intermittent test time (↑ 22%, P?.05), force–time integral (↑ 28%, P?.05) and faster muscle re-oxygenation (↑ 32%, P?.05), when compared to the hand over hold condition. Further, the ratio of intermittent to continuous test time distinguished specific aerobic muscular adaptations among sport climbers (2.02), boulderers (1.74) and lower grade climbers (1.25). Lower grade climbers and boulderers produced shorter duration contractions due to the slower development of target force during the intermittent test, indicating worse kinaesthetic differentiation. Both the type of recovery and climbing discipline determined muscle re-oxygenation and intermittent performance in rock climbers. 相似文献
36.
Andreas Bauer Jan Romberg Bernhard Sch?tz 《Informatik - Forschung und Entwicklung》2005,49(3):194-205
Zur Beherrschung der komplexen vernetzten und verteilten Funktionen von Automotive-Software ist eine Beschreibung des zu erstellenden
Systems auf verschiedenen Abstraktionsebenen und schrittweise überg?nge zwischen diesen Ebenen notwendig. Neben der Definition
geeigneter Ebenen werden zur Unterstützung echtzeitkritischer Systemanteile ein einheitliches Berechnungsmodell, ebenenspezifische
Beschreibungstechniken, sowie methodische Regeln für diese Abstraktionsebenen eingeführt und in den Werkzeugprototypen AutoFocus integriert. 相似文献
37.
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39.
This longitudinal study was aimed at increasing our understanding of how teachers learn. It was conducted within a national innovation programme in secondary education. During one year 94 teachers reported six learning experiences using digital logs. The learning experiences were content-analysed in terms of learning activities and learning outcomes. The former comprised six main categories, namely experimenting, considering own practice, getting ideas from others, experiencing friction, struggling not to revert to old ways, and avoiding learning—the first two categories being reported most frequently. Reported learning outcomes referred to changes in knowledge and beliefs, emotions, practices, and intentions for practice, with changes in knowledge and beliefs being reported most frequently and changes in teaching practices being reported rarely. Learning activities were associated significantly with all measures of learning outcomes. Type of learning environment was significantly associated with learning activities and learning outcomes. Results are discussed with respect to ways of fostering teacher learning. 相似文献
40.