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1.
Comparing the pre- and post-impact ball and racquet kinematics of elite tennis players' first and second serves: a preliminary study 总被引：1，自引：0，他引：1
Chow JW Carlton LG Lim YT Chae WS Shim JH Kuenster AF Kokubun K 《Journal of sports sciences》2003,21(7):529-537
The aim of this study was to compare the pre- and post-impact three-dimensional kinematics of the ball and racquet during first and second serves performed by elite tennis players. Data were collected from four male and four female right-handed professional players during competition using two high-speed cameras (200 Hz). For each player, one first serve and one second serve from the 'deuce' or right service court that landed within the specified target area were analysed. To test for significant differences between the first and second serves, Wilcoxon tests (P < or = 0.05) were performed on selected parameters. The results indicate that the ball travelled forward and to the left during the flight phase of the toss in all but one trial. The average pre-impact ball forward location for the first serve was significantly more in front and had a higher associated forward ball velocity than the corresponding values for the second serve. On average, the decrease in post-impact ball speed from the first to the second serve was 24.1%. No significant differences between the first and second serves were found in the pre-impact racquet head speed and orientation, which was represented as a unit vector perpendicular to the racquet face. The major adjustments made by the players when going from the first to second serve were a decrease in pre-impact ball forward location (P < or = 0.01) and an increase in the pre-impact racquet vertical and lateral velocities (both P < or = 0.05). This implies that the players tossed the ball closer to the body and imparted topspin and sidespin on the ball by changing the racquet vertical and lateral velocities when going from the first to the second serve. 相似文献
2.
This study examines whether levels of father engagement (e.g., verbal stimulation, caregiving, and physical play) vary by race/ethnicity using a model that controls for fathers' human capital, mental health, and family relationships. It also tests whether the models work similarly across race/ethnic groups. Its sample of N=5,089 infants and their families is drawn from the Early Childhood Longitudinal Study - Birth Cohort (ECLS-B). We found that, after including controls, African American and Latino fathers had higher levels of engagement in caregiving and physical play activities than White fathers. There were no differences in verbal stimulation activities across race/ethnicity. Fathers' education (college level) predicted more verbally stimulating activities whereas fathers' report of couple conflict predicted less caregiving and physical play. Although levels of engagement differed across the groups, the overall models did not differ by race/ethnicity, except for physical play. African American mothers who reported high levels of depressive symptoms had partners who engaged in more physical play than White mothers with high levels of depressive symptoms. 相似文献
3.
Paul Kyuman Chae 《Psychology in the schools》1999,36(3):179-185
The Continuous Performance Test (CPT), such as the Test of Variable Attention (TOVA), is widely used in the assessment of ADHD with other behavioral ratings and observations. Since some clinicians argue that CPTs measure psychomotor speed function rather than sustained attention, a correlation study between PIQ of WISC‐III and TOVA was conducted to find out if a significant relationship of any kind existed. Forty children with ADHD were studied, and the results indicated that there was no correlation between TOVA and PIQ of WISC‐III. © 1999 John Wiley & Sons, Inc. 相似文献
4.
Many studies mention the importance of national e-Strategy as it is a vital contributing factor for ICT-enabled development. However, it is difficult to find a conceptual framework that suggests how the national e-Strategy should be defined and applied by the target country. This creates more confusion for policy makers. This paper reviews previous research on national e-Strategies to recognize its significance as a major contributing factor. Based on that, this research defines the critical success factors of national e-Strategy and investigates the possibility of prioritizing factors by the scale of economy through a Delphi survey. By reviewing the evaluated status of e-Readiness and co-relating the evaluation with economic status, we may further investigate the significance of the digital divide and national e-Strategy. The outcome of this research may be applicable in differentiating critical success factors from general ingredients of National e-Strategy. 相似文献
5.
Jun Y Cho Dae Y Hwang Tae S Kang Dong H Shin Jin H Hwang Chae H Lim 《Journal of sports sciences》2013,31(11):943-951
In its late stage, Alzheimer's disease results in progressive muscle weakness in the arms and legs. The aim of this study was to determine whether mice expressing the skeletal muscle-specific mutant PS2 gene (a model of Alzheimer's disease) are a useful experimental system to study the protective effect of exercise on Aβ-42 reduction, improvement of behavioural function and changes in metabolic parameters. With this aim in mind, the transgenic mice were subjected to treadmill exercise for 3 months. The results showed that in transgenic mice, but not in normal mice, treadmill exercise resulted in a reduction of Aβ-42 deposits and an improvement in behavioural function, thereby restoring normal concentrations of total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol and triglyceride. Thus, exercise may represent a practical therapeutic strategy for use with human patients with Alzheimer's disease. 相似文献
6.
Gene H. Brody Man‐Kit Lei David H. Chae Tianyi Yu Steven M. Kogan Steven R. H. Beach 《Child development》2014,85(3):989-1002
This study was designed to examine the prospective relations of perceived racial discrimination with allostatic load (AL), along with a possible buffer of the association. A sample of 331 African Americans in the rural South provided assessments of perceived discrimination from ages 16 to 18 years. When youth were 18 years, caregivers reported parental emotional support and youth assessed peer emotional support. AL and potential confounder variables were assessed when youth were 20. Latent growth mixture modeling identified two perceived discrimination classes: high and stable, and low and increasing. Adolescents in the high and stable class evinced heightened AL even with confounder variables controlled. The racial discrimination to AL link was not significant for young adults who received high emotional support. 相似文献
7.
Lumbar spinal loads and muscle activity during a golf swing 总被引：1，自引：0，他引：1
Lim YT Chow JW Chae WS 《Sports biomechanics / International Society of Biomechanics in Sports》2012,11(2):197-211
This study estimated the lumbar spinal loads at the L4-L5 level and evaluated electromyographic (EMG) activity of right and left rectus abdominis, external and internal obliques, erector spinae, and latissimus dorsi muscles during a golf swing. Four super VHS camcorders and two force plates were used to obtain three-dimensional (3D) kinematics and kinetics of golf swings performed by five male collegiate golfers. Average EMG levels for different phases of golf swing were determined. An EMG-assisted optimization model was applied to compute the contact forces acting on the L4-L5. The results revealed a mean peak compressive load of over six times the body weight (BW) during the downswing and mean peak anterior and medial shear loads approaching 1.6 and 0.6 BW during the follow-through phases. The peak compressive load estimated in this study was high, but less than the corresponding value (over 8 BW) reported by a previous study. Average EMG levels of different muscles were the highest in the acceleration and follow-through phases, suggesting a likely link between co-contractions of paraspinal muscles and lumbar spinal loads. 相似文献
8.
The aim of this study was to identify those kinematic characteristics that are most closely related to an athlete's medical classification and measured distance of a put. Two S-VHS camcorders (60 fields per second) were used to record the performance of 17 males of different classes. Each participant performed six trials and the best trial for each was selected for analysis. Three-dimensional kinematics of the shot and upper body segments at the instant of release and during the forward thrust (delivery) were determined. The average speeds and angles of the shot at release for different classes (5.3-7.8 ms -1 and 21.2 to 34.4°, respectively) were smaller than those exhibited by elite male able-bodied throwers. The height of the shot at release, the angular speed of the upper arm at release, the range of motion of the shoulder girdle during the delivery, and the average angular speeds of the trunk, shoulder girdle and upper arm during the delivery, were all significantly correlated with both the classification and measured distance ( P ? 0.05). The results indicate the importance of achieving a high average angular speed for each upper body segment during the delivery. 相似文献
9.
Gradual refinement for application-specific MPSoC design from Simulink model to RTL implementation 总被引：1，自引：0，他引：1
Kai Huang Xiao-lang Yan Sang-il Han Soo-ik Chae Ahmed A. Jerraya Katalin Popovici Xavier Guerin Lisane Brisolara Luigi Carro 《浙江大学学报(A卷英文版)》2009,10(2):151-164
The application-specific multiprocessor system-on-chip （MPSoC） architecture is becoming an attractive solution to deal with increasingly complex embedded applications, which require both high performance and flexible programmability. As an effective method for MPSoC development, we present a gradual refinement flow starting from a high-level Simulink model to a synthesizable and executable hardware and software specification. The proposed methodology consists of five different abstract levels： Simulink combined algorithm and architecture model （CAAM）, virtual architecture （VA）, transactional accurate architecture （TA）, virtual prototype （VP） and field-programmable gate array （FPGA） emulation. Experimental results of Motion-JPEG and H.264 show that the proposed gradual refinement flow can generate various MPSoC architectures from an original Simulink model, allowing processor, communication and tasks design space exploration. 相似文献
10.
Soo Eun Chae 《Journal of College Student Psychotherapy》2017,31(1):59-70
Psychodrama was first introduced in the Korean literature in 1972, but its generalization to college students did not occur until the 1990s. Despite findings from psychodrama studies with Korean college students supporting psychodrama as effective for developing and maintaining good interpersonal relationships, as well as decreasing anxiety and stress, it is still underutilized in South Korea. Accordingly, the current study looked at implementing a psychodrama program in South Korean universities. The positive results of the program implementation suggest that psychodrama is a useful technique for improving Korean college students’ general development and mental stability including secure attachment. 相似文献