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1.
Kersting S 《Journal of deaf studies and deaf education》1997,2(4):252-263
This qualitative study of the social aspects of mainstreaming from the perspective of deaf college students indicates that for some students, social adjustment to college is complicated by experiences of separation and alienation from both deaf and hearing peers. Data were collected through open-ended interviews with deaf students who had little or no previous experience with or exposure to deaf culture or language before their arrival at a mainstream college environment. Feelings of isolation, loneliness, and resentment were most intense during orientation and first year, when alienation from the deaf student community appeared to be caused by lack of sign language skills, unfamiliarity with norms and values of deaf culture, and perceived hostility from deaf peers. Simultaneous experiences of separation from hearing peers appeared to be caused by physical barriers inherent in the classroom, residence hall, and cafeteria environments, as well as by discrimination from hearing peers, who tended to stereotype deaf students. Findings suggest that those involved in the administration and delivery of postsecondary programs for the deaf should investigate the experiences of students who arrive on campus without knowledge of sign language or familiarity with deaf culture and evaluate currently existing programs and services designed to meet these students' needs. 相似文献
2.
Saeideh Heshmati Nicole Kersting Taliesin Sutton 《International Journal of Science and Mathematics Education》2018,16(4):777-796
This study explored the design and implementation of the Cover-up and Un-cover games, two manipulative-based fraction games, in 14 fifth-grade classrooms. We examined how the fraction concepts were integrated into the game design and explored the nature of teacher-student interactions during games using lesson videos. Our examination showed that interactions focused on game progress, rules, and turn taking with little exploration of strategies or the underlying mathematics. To compare the quality of teacher-student interactions during games with interaction quality during other instructional activities, we coded 5 videotaped lessons from each of the 14 classrooms. Statistical results from a dependent t test indicated that teacher-student interactions were of statistically significant lower quality during games than during non-game segments with similar instructional purpose. Teachers might benefit from additional curriculum support and training to implement games as rich mathematical learning opportunities. 相似文献
3.
The authors examined whether feedback from student ratings of instruction not augmented with consultation helps college teachers
to improve their student ratings on a long-term basis. The study reported was conducted in an institution where no previous
teaching-effectiveness evaluations had taken place. At the end of each of four consecutive semesters, student ratings were
assessed and teachers were provided with feedback. Data from 3122 questionnaires evaluating 12 teachers were analyzed using
polynomial and piecewise random coefficient models. Results revealed that student ratings increased from the no-feedback baseline
semester to the second semester and then gradually decreased from the second to the fourth semester, although feedback was
provided after each semester. The findings suggest that student ratings not augmented with consultation are far less effective
than typically assumed when considered from a long-term perspective. 相似文献
4.
René E.D. Ferdinands Uwe G. Kersting 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(3):315-333
Cricket bowling is traditionally thought to be a rigid-arm motion, allowing no elbow straightening during the delivery phase. Conversely, research has shown that a perfectly rigid arm through delivery is practically unattainable, which has led to rule changes over the past years. The current rule requires a bowler not to increase the elbow angle by more than 15°, thus requiring a measurement to confirm legality in “suspect” bowlers. The aims of this study were to evaluate whether the current rule is maintained over a range of bowlers and bowling styles, and to ascertain whether other kinematics measures may better differentiate between legal and suspect bowling actions. Eighty-three bowlers of varying pace were analysed using reflective markers and a high-speed (240 Hz) eight-camera motion analysis system in a laboratory. The change in elbow segment angle (minimum angle between the arm and forearm), the change in elbow extension angle with respect to the flexion–extension axis of a joint coordinate system, and the elbow extension angular velocity at ball release were measured. We found that bowlers generally bowled within a change in elbow extension angle of 15°. However, this limit was unable to differentiate groups of bowlers from those who were suspected of throwing in the past. Improved differentiation was attained using the elbow extension angular velocity at ball release. The elbow extension angular velocity at ball release may be conceptually more valid than the elbow extension angle in determining which bowlers use the velocity-contributing mechanisms of a throw. Also, a high value of elbow extension angular velocity at ball release may be related to the visual impression of throwing. Therefore, it is recommended that researchers and cricket legislators examine the feasibility of specifying a limit to the elbow extension angular velocity at ball release to determine bowling legality. 相似文献
5.
Rene Ferdinands Robert N. Marshall Uwe Kersting 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(3):139-152
Kinematic studies have shown that fast bowlers have run-up velocities, based on centre of mass velocity calculations, which are comparable to elite javelin throwers. In this study, 34 fast bowlers (22.3 ± 3.7 years) of premier grade level and above were tested using a three-dimensional (3-D) motion analysis system (240 Hz). Bowlers were divided into four speed groups: slow-medium, medium, medium-fast, and fast. The mean centre of mass velocity at back foot contact (run-up speed) was 5.3 ± 0.6 m/s. Centre of mass velocity at back foot contact was significantly faster in the fastest two bowling groups compared to the slow-medium bowling group. In addition, stepwise multiple regression analysis showed that the centre of mass deceleration over the delivery stride phase was the strongest predictor of ball speed in the faster bowling groups. In conclusion, centre of mass kinematics are an important determinant of ball speed generation in fast bowlers. In particular, bowlers able to coordinate their bowling action with periods of centre of mass deceleration may be more likely to generate high ball speed. 相似文献
6.
Ferdinands RE Kersting UG 《Sports biomechanics / International Society of Biomechanics in Sports》2007,6(3):315-333
Cricket bowling is traditionally thought to be a rigid-arm motion, allowing no elbow straightening during the delivery phase. Conversely, research has shown that a perfectly rigid arm through delivery is practically unattainable, which has led to rule changes over the past years. The current rule requires a bowler not to increase the elbow angle by more than 15 degrees, thus requiring a measurement to confirm legality in "suspect" bowlers. The aims of this study were to evaluate whether the current rule is maintained over a range of bowlers and bowling styles, and to ascertain whether other kinematics measures may better differentiate between legal and suspect bowling actions. Eighty-three bowlers of varying pace were analysed using reflective markers and a high-speed (240 Hz) eight-camera motion analysis system in a laboratory. The change in elbow segment angle (minimum angle between the arm and forearm), the change in elbow extension angle with respect to the flexion-extension axis of a joint coordinate system, and the elbow extension angular velocity at ball release were measured. We found that bowlers generally bowled within a change in elbow extension angle of 15.5 degrees. However, this limit was unable to differentiate groups of bowlers from those who were suspected of throwing in the past. Improved differentiation was attained using the elbow extension angular velocity at ball release. The elbow extension angular velocity at ball release may be conceptually more valid than the elbow extension angle in determining which bowlers use the velocity-contributing mechanisms of a throw. Also, a high value of elbow extension angular velocity at ball release may be related to the visual impression of throwing. Therefore, it is recommended that researchers and cricket legislators examine the feasibility of specifying a limit to the elbow extension angular velocity at ball release to determine bowling legality. 相似文献
7.
本文分析了MATLAB软件在机械优化设计中常用的线性规划、一维优化、无约束非线性优化及约束非线性优化四种优化问题的标准数学模型、调用函数及参数的设置。并以具体实例对利用MATLAB解决优化问题的具体过程进行了详细的阐述,该过程可以供工程设计人员参考,以提高优化设计效率。 相似文献
8.
AbstractThe mechanics of cutting movements have been investigated extensively, but few studies have considered the rapid deceleration phase prior to turning which has been linked to muscle damage. This study used accelerometry to examine the influence of turning intensity on the last three steps of a severe turn.Ten soccer players performed 135° “V” cuts at five different intensities. Resultant decelerations were recorded from a trunk-mounted tri-axial accelerometer. Lower limb kinematics and ground reaction forces (GRF) from the pivot foot-ground contact (FGC) were also monitored.Average peak trunk decelerations were larger at the two preceding steps (4.37 ± 0.12 g and 4.58 ± 0.11 g) compared to the PIVOT step (4.10 ± 0.09 g). Larger peak joint flexion angular velocities were observed at PRE step (ankle: 367 ± 192 deg.s?1; knee 493 ± 252 deg.s?1) compared to PIVOT step (ankle 255 ± 183 deg.s?1; knee 377 ± 229 deg.s?1). Turn intensity did not influence peak GRF at PIVOT step.This study highlights the importance of steps prior to turning and their high-frequency loading characteristics. It is suggested that investigations of lower limb loading during turning should include this deceleration phase and not focus solely on pivot FGC. 相似文献
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Ferdinands R Marshall RN Kersting U 《Sports biomechanics / International Society of Biomechanics in Sports》2010,9(3):139-152
Kinematic studies have shown that fast bowlers have run-up velocities, based on centre of mass velocity calculations, which are comparable to elite javelin throwers. In this study, 34 fast bowlers (22.3 +/- 3.7 years) of premier grade level and above were tested using a three-dimensional (3-D) motion analysis system (240 Hz). Bowlers were divided into four speed groups: slow-medium, medium, medium-fast, and fast. The mean centre of mass velocity at back foot contact (run-up speed) was 5.3 +/- 0.6 m/s. Centre of mass velocity at back foot contact was significantly faster in the fastest two bowling groups compared to the slow-medium bowling group. In addition, stepwise multiple regression analysis showed that the centre of mass deceleration over the delivery stride phase was the strongest predictor of ball speed in the faster bowling groups. In conclusion, centre of mass kinematics are an important determinant of ball speed generation in fast bowlers. In particular, bowlers able to coordinate their bowling action with periods of centre of mass deceleration may be more likely to generate high ball speed. 相似文献