Dynamics of the martial arts high front kick

Fast unloaded movements (i.e. striking, throwing and kicking) are typically performed in a proximo‐distal sequence, where initially high proximal segments accelerate while distal segments lag behind, after which proximal segments decelerate while distal segments accelerate. The aims of this study were to examine whether proximal segment deceleration is performed actively by antagonist muscles or is a passive consequence of distal segment movement, and whether distal segment acceleration is enhanced by proximal segment deceleration. Seventeen skilled taekwon‐do practitioners were filmed using a high‐speed camera while performing a high front kick. During kicking, EMG recordings were obtained from five major lower extremity muscles. Based on the kinematic data, inverse dynamics computations were performed yielding muscle moments and motion‐dependent moments. The results indicated that thigh deceleration was caused by motion‐dependent moments arising from lower leg motion and not by active deceleration. This was supported by the EMG recordings. Lower leg acceleration was caused partly by a knee extensor muscle moment and partly by a motion‐dependent moment arising from thigh angular velocity. Thus, lower leg acceleration was not enhanced by thigh deceleration. On the contrary, thigh deceleration, although not desirable, is unavoidable because of lower leg acceleration.     

Exploring the relationship between school discipline referrals and delinquency

There is a growing concern about violent and destructive behaviors of youth that require intervention by juvenile justice and youth‐serving agencies. This concern has led many to conclude that schools and community agencies must increase efforts to prevent juvenile delinquency and to provide programs that will facilitate rehabilitation, education, and vocational training for youth already involved. A clear understanding of the nature and range of behaviors that result in juvenile crime is needed in order to develop programs and interventions that can be expected to lead to beneficial changes for youth and for society as a whole. The purpose of this article is to describe the relationship between school behaviors and youth characteristics in school (e.g., discipline referrals, teacher nominations, nomothetic ratings) and referrals to juvenile authorities (e.g., illegal behaviors). We describe a strategy of using teacher nominations, school discipline referrals, and community arrest data to predict delinquent and violent behavior in youth. We outline data from a group of socially maladjusted middle school youth to illustrate the relationship between the two data sources and recommendations for identification and treatment of youth at risk for delinquency and antisocial behavior. © 2001 John Wiley & Sons, Inc.     

Moving an Evidence‐Based Parenting Program Into the Community

Attachment and Biobehavioral Catch‐up (ABC) is a parenting program developed to enhance sensitivity among parents of infants who experience early adversity. In several randomized clinical trials, the intervention's efficacy has been demonstrated. Moving interventions into the community with adequate fidelity is challenging, though, and intervention effects are often much smaller than when tested in randomized clinical trials. To enhance the likelihood that ABC is delivered with high fidelity, a microanalytic fidelity assessment was developed. Using this fidelity tool as a central component of training, supervision, and certification, changes in parent sensitivity for 108 families with children ages 6 months to 2 years were as large as those seen in laboratory settings. These findings are discussed with regard to implications for moving other evidence‐based interventions into the community.     

Investigatory behavior inthe plains garter snake (Thamnophis radix) and several additional species

Garter snakes (Thamnophis radix), hognose snakes (Heterodon platyrhinos), and rattlesnakes (Crotalus species) flick their tongues and crawl about in an open field containing no food or sexual (i.e., reproductive) odors. As Experiment I shows, the taxa differ reliably in both rate of tongue flicking and rate of locomotion. In Experiment II, garter snakes (Thamnophis radix) placed into an open field for 5 min showed more tongue flicking than snakes that were handled and placed directly back into their home cages, indicating that the first group was exploring the apparatus rather than responding only to handling. During Minutes 3 through 5 (Experiment III) in the open field, garter snakes emitted fewer tongue flicks than they did during the first minute, and after 20 min, the rate of tongue flicking was virtually zero. However, snakes were capable of responding to presentation of new objects and/or odors, indicating that the previous response decrement was not derived from effector fatigue but rather from some habituatory process. Experiment IV revealed that satiated snakes habituated more rapidly than hungry snakes during exploration of the open field. Hence, exploratory behavior in these snakes is at least partially under the control of the same factors which mediate food-related appetitive activities.     

Biomechanical differences in soccer kicking with the preferred and the non-preferred leg

The aims of this study were to examine the release speed of the ball in maximal instep kicking with the preferred and the non-preferred leg and to relate ball speed to biomechanical differences observed during the kicking action. Seven skilled soccer players performed maximal speed place kicks with the preferred and the nonpreferred leg; their movements were filmed at 400 Hz. The inter-segmental kinematics and kinetics were derived. A coefficient of restitution between the foot and the ball was calculated and rate of force development in the hip flexors and the knee extensors was measured using a Kin-Com dynamometer. Higher ball speeds were achieved with the preferred leg as a result of the higher foot speed and coefficient of restitution at the time of impact compared with the non-preferred leg. These higher foot speeds were caused by a greater amount of work on the shank originating from the angular velocity of the thigh. No differences were found in muscle moments or rate of force development. We conclude that the difference in maximal ball speed between the preferred and the non-preferred leg is caused by a better inter-segmental motion pattern and a transfer of velocity from the foot to the ball when kicking with the preferred leg.     

Low-cost method of removing periodical duplicates using a collection growth formula at a medium-sized academic library

The authors detail a low-cost, two-phased formula-based approach to bound periodical weeding at a medium-sized academic library with the goal of opening space for five years' growth, while still meeting user needs. Phase I included weeding bound titles with overlapping microfilm holdings. Phase II used the following criteria to determine which titles to discard: (1) four or fewer items, (2) availability in the University of Wisconsin System, (3) usage statistics and online access, (4) department consultation. This article summarizes the design, implementation, and successful results of the project.     

How is professionals’ information seeking shaped by workplace procedures? A study of healthcare clinicians

Professional work is often regulated by procedures that shape the information seeking involved in performing a task. Yet, research on professionals’ information seeking tends to bypass procedures and depict information seeking as an informal activity. In this study we analyze two healthcare tasks governed by procedures: triage and timeouts. While information seeking is central to both procedures, we find that the coordinating nurses rarely engage in information seeking when they triage patients. Inversely, the physicians value convening for timeouts to seek information. To explain these findings we distinguish between junior and expert professionals and between uncertain and equivocal tasks. The triage procedure specifies which information to retrieve but expert professionals such as the coordinating nurses tend to perform triage, which is an uncertain task, by holistic pattern recognition rather than information seeking. For timeouts, which target an equivocal task, the procedure facilitates information seeking by creating a space for open-ended collaborative reflection. Both junior and expert physicians temporarily suspend patient treatment in favor of this opportunity to reflect on their actions, though partly for different reasons. We discuss implications for models of professionals’ information seeking.     

Biomechanical differences in soccer kicking with the preferred and the non-preferred leg

The aims of this study were to examine the release speed of the ball in maximal instep kicking with the preferred and the non-preferred leg and to relate ball speed to biomechanical differences observed during the kicking action. Seven skilled soccer players performed maximal speed place kicks with the preferred and the non-preferred leg; their movements were filmed at 400 Hz. The inter-segmental kinematics and kinetics were derived. A coefficient of restitution between the foot and the ball was calculated and rate of force development in the hip flexors and the knee extensors was measured using a Kin-Com dynamometer. Higher ball speeds were achieved with the preferred leg as a result of the higher foot speed and coefficient of restitution at the time of impact compared with the non-preferred leg. These higher foot speeds were caused by a greater amount of work on the shank originating from the angular velocity of the thigh. No differences were found in muscle moments or rate of force development. We conclude that the difference in maximal ball speed between the preferred and the non-preferred leg is caused by a better inter-segmental motion pattern and a transfer of velocity from the foot to the ball when kicking with the preferred leg.     

A study of stearyl alcohol bloom on Dan Hill PVC dolls and the influence of temperature

A study was conducted to investigate white bloom found on more than 130 polyvinyl chloride (PVC) dolls from the 1980s and 1990s produced by the Danish factory Dan Hill Plast A/S. The bloom was discovered on the dolls after 10 years of storage in a climate controlled facility with average temperature at 11–12°C and a relative humidity at 50?±?5%. Analysis of the dolls and the bloom was carried out using Fourier transform infrared spectroscopy, which revealed that the bloom consisted primarily of stearyl alcohol. Subsequent analysis with gas chromatography–mass spectrometry showed a minor presence of cetyl alcohol. It is proposed that the alcohol had been added as a lubricant to aid flow during processing. The stearyl alcohol was almost completely reabsorbed into the PVC dolls following one month storage at room temperature, suggesting that low temperature storage played a decisive role in the appearance of the bloom. It is likely that a decrease in temperature has led to a decrease in compatibility of the stearyl alcohol in the PVC compound, thus promoting its exudation. This paper also discusses an extreme bloom of white crystals on other PVC dolls of unknown provenance.