The impact of load on lower body performance variables during the hang power clean     

Timothy J. Suchomel  George K. Beckham  Glenn A. Wright 《Sports biomechanics / International Society of Biomechanics in Sports》2014,13(1):87-95

This study examined the impact of load on lower body performance variables during the hang power clean. Fourteen men performed the hang power clean at loads of 30%, 45%, 65%, and 80% 1RM. Peak force, velocity, power, force at peak power, velocity at peak power, and rate of force development were compared at each load. The greatest peak force occurred at 80% 1RM. Peak force at 30% 1RM was statistically lower than peak force at 45% (p = 0.022), 65% (p = 0.010), and 80% 1RM (p = 0.018). Force at peak power at 65% and 80% 1RM was statistically greater than force at peak power at 30% (p < 0.01) and 45% 1RM (p < 0.01). The greatest rate of force development occurred at 30% 1RM, but was not statistically different from the rate of force development at 45%, 65%, and 80% 1RM. The rate of force development at 65% 1RM was statistically greater than the rate of force development at 80% 1RM (p = 0.035). No other statistical differences existed in any variable existed. Changes in load affected the peak force, force at peak power, and rate of force development, but not the peak velocity, power, or velocity at peak power.  相似文献   

The effect of national culture on partner buyouts in cross-border biotechnology alliances     

Timothy B. Folta  Walter J. Ferrier 《The Journal of High Technology Management Research》2000,11(2):175-198

This study examines how national culture influences the likelihood and rate of buyouts among R&D equity alliances and joint ventures in the biotechnology industry. We hypothesize that the interaction of specific national culture attributes and cultural differences between alliance partners have an impact on: (1) the amount of endogenous uncertainty surrounding the potential integration of the target firm and (2) the marginal rate of learning in hierarchical versus collaborative governance. Applying a competing hazard model to a sample of 173 joint ventures and minority equity collaborations in the biotechnology industry, we found that investing firms from high power distance and high uncertainty avoidance countries are more likely to buy out their alliance partners. Furthermore, greater cultural distance between alliance partners increases the likelihood of partner buyout when investing firms are from high power distance countries.  相似文献   

Conditionalizing on Knowledge   总被引：1，自引：0，他引：1  

Williamson  Timothy 《The British journal for the philosophy of science》1998,49(1):89-121

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Planning for Andrew: the use of COACH and VISTA in an inclusive preschool program     

Michael F. Giangreco  Timothy Whiteford  Lucie Whiteford  Mary Beth Doyle 《International Journal of Disability, Development & Education》1998,45(4):375-396

This case study chronicles the use of two educational planning tools, COACH (Choosing Outcomes and Accommodations for Children: A Guide to Educational Planning for Students with Disabilities) and VISTA (Vermont Interdependent Services Team Approach: A Guide to Coordinating Educational Support Services) for Andrew, a 4‐year‐old child with Down syndrome, who attends a general education preschool. The article documents the decisions his team made using COACH and VISTA and describes the findings of follow‐up interviews with his parents, preschool teacher, special educator, and speech/language pathologist. The findings offer insights into the benefits and limitations of these approaches at the preschool level. Implications for facilitating communication and decision‐making among team members are discussed.  相似文献   

Plato: Images,Aims, and Practices of Education*     

Timothy L. Simpson 《Educational theory》2020,70(2):231-242

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Shock and impact reduction in moderate and strenuous landing activities     

Zhang S  Derrick TR  Evans W  Yu YJ 《Sports biomechanics / International Society of Biomechanics in Sports》2008,7(2):296-309

Shock reduction has been well studied in moderate activities such as walking and running. However, there is a clear lack of research concerning shock wave transmission and reduction in more strenuous landing activities. In this study, we examined the impact of shock transmission and reduction in landing activities with varied mechanical demands. Ten active males were recruited for the study. They performed five successful step-off landing trials from each of five heights: 30, 45, 60, 75, and 90 cm. Right sagittal kinematics, ground reaction forces, and acceleration were recorded simultaneously. Impact frequencies were analysed using a discrete Fast Fourier Transform and power spectral density was computed. Increased range of motion for the ankle, knee, and hip joints was observed at higher landing heights. The peaks of the vertical ground reaction force, forehead and tibial accelerations, and eccentric muscle work by lower extremity joints were increased with increased landing heights. The peak head power spectral density was severely attenuated at higher frequencies but the peak tibia power spectral density did not demonstrate this trend. Shock reduction showed increased reduction at higher frequencies, but minimal changes across five landing heights. Unlike the responses observed for walking and running, the shock reduction did not show significant improvement with elevated mechanical demands.  相似文献   

The effect of self-regulated and experimenter-imposed practice schedules on motor learning for tasks of varying difficulty     

Keetch KM  Lee TD 《Research quarterly for exercise and sport》2007,78(5):476-486

Research suggests that allowing individuals to control their own practice schedule has a positive effect on motor learning. In this experiment we examined the effect of task difficulty and self-regulated practice strategies on motor learning. The task was to move a mouse-operated cursor through pattern arrays that differed in two levels of difficulty. Participants learned either four easy or hard patterns after assignment to one of four groups that ordered practice in blocked, random, self-regulated, and yoked-to-self-regulated schedules. Although self-regulation provided no special benefit in acquisition, these groups showed the most improved performance in retention, irrespective of task difficulty. Although individual switch strategies for members of the self-regulated groups were quite variable, the impact of self-regulation on motor learning remained similar. These findings add to the growing body of literature suggesting that self-regulated practice is an important variable for motor learning.  相似文献   

Does film criticism affect box office earnings? Evidence from movies released in the U.S. in 2003     

Timothy King 《Journal of Cultural Economics》2007,31(3):171-186

In a market characterized by a very large number of consumers, irregularly and infrequently choosing from a constantly changing menu of possibilities, widely available impartial information and advice would be expected to make a significant impact on demand. In the U.S. in 2003, however, there was zero correlation between critical ratings for films and gross box office earnings. For movies released on more than 1,000 screens, critical ratings were indeed positively related to gross earnings, and, together with production budgets and the number of opening screens, explained more than half the variance. But films with only limited opening release received higher average ratings. This is especially the case for foreign movies and documentaries but also true for American films, whose ratings, though positively related to the box office, seldom have enough influence to propel a movie into later wide exhibition or high earnings.

Timothy KingEmail:

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Training physical education students to self-regulate during basketball free throw practice     

Cleary TJ  Zimmerman BJ  Keating T 《Research quarterly for exercise and sport》2006,77(2):251-262

The additive effects of self-regulation training in forethought, performance, and self-reflection phase processes on acquiring a novel motoric skill (i.e., basketball free throws) and self-reflective beliefs were studied with 50 college students. The results showed a positive linear trend between the number of self-regulatory phases, in which the participants were trained, and their free throw shooting performance and shooting adaptation. The two- and three-phase training groups displayed significantly more accurate free throws and were able to self-correct their shooting form more frequently following missed shots than all other groups. Participants who received three-phase training displayed the most adaptive motivational profile, characterized by making strategic attributions and adaptive inferences and by using self/process criteria during self-evaluations.  相似文献   

Effects of sensory-level high-volt pulsed electrical current ondelayed-onset muscle soreness     

Tourville TW  Connolly DA  Reed BV 《Journal of sports sciences》2006,24(9):941-949

Ten healthy males and ten healthy females aged 21.5 +/- 3.2 years (mean +/- s) participated in the study, which was designed to evaluate the effectiveness of sensory level-high volt pulsed electrical current (HVPC) on delayed-onset muscle soreness (DOMS). Arm discomfort, elbow extension range of motion and isometric elbow flexion strength were obtained as baseline measurements. Delayed-onset muscle soreness was induced in the participants' dominant or non-dominant arm using two sets of 20 maximal eccentric elbow flexion contractions. After the induction of DOMS, the participants were randomly divided into an experimental condition (HVPC) or a placebo condition. The experimental condition consisted of 20 min of HVPC immediately after the induction of DOMS, and 20 min every 24 h for three consecutive days thereafter. The participants in the placebo condition received an intervention similar in design; however, no electrical current was administered. Baseline measurements were reevaluated at 24, 48, 72 and 96 h after the induction of DOMS. Three weeks later, the participants returned and the protocol was repeated on the contralateral limb, using the opposite intervention (HVPC or placebo). Repeated-measures analysis of variance revealed a significant increase in overall arm discomfort, decrease in elbow extension and decrease in isometric strength for both conditions over time. No significant main effect of treatment, or time-by-treatment interaction, was found for the HVPC condition when compared with the placebo condition for any variable. Sensory-level HVPC, as utilized in our application, was ineffective in reducing the measured variables associated with DOMS.  相似文献