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101.
Abstract

Fatigue curves for the forearm muscles, doing maximal static and dynamic work, were obtained under control conditions and under conditions of hyperaemia. The hyperaemia was evoked by subjecting the muscles of the forearm for a specific length of time to circulatory occlusion with a blood pressure cuff and then suddenly releasing the cuff pressure. The maximal increase in forearm volume, resulting from the postocclusion hyperaemia, followed a mathematical curve when it was expressed as a function of the occlusion time. A significant decrement in work capacity was found immediately after ten minutes of occlusion. This short-time negative influence did not affect the total output.  相似文献   
102.
Attachment and Adolescent Psychosocial Functioning   总被引:8,自引:1,他引:8  
To explore the meaning and function of attachment organization during adolescence, its relation to multiple domains of psychosocial functioning was examined in a sample of 131 moderately at-risk adolescents. Attachment organization was assessed using the Adult Attachment Interview; multiple measures of functioning were obtained from parents, adolescents, and their peers. Security displayed in adolescents' organization of discourse about attachment experiences was related to competence with peers (as reported by peers), lower levels of internalizing behaviors (as reported by adolescents), and lower levels of deviant behavior (as reported by peers and by mothers). Preoccupation with attachment experiences, seen in angry or diffuse and unfocused discussion of attachment experiences, was linked to higher levels of both internalizing and deviant behaviors. These relations generally remained even when other attachment-related constructs that had been previously related to adolescent functioning were covaried in analyses. Results are interpreted as suggesting an important role for attachment organization in a wide array of aspects of adolescent psychosocial development.  相似文献   
103.
Abstract

The influence of perceptions of the motivational climate and perceived ability on situational motivation and the physical activity behavior of 213 male and 229 female adolescent physical education students (M age= 12.56 years; SD = 0.96) was examined over a 3-day period. A significant age by gender interaction emerged, with physical activity declining from the sixth to eighth grade. The decline was more pronounced among female than male students. Perceptions of a mastery climate were strongly related to more self-determined forms of situational motivation. In contrast, perceptions of a performance climate were strongly related to less self-determined forms of situational motivation. Results of a hierarchical regression analysis revealed gender, perceived ability, and perceptions of a mastery climate to explain a significant amount of variance in physical activity. These findings suggest that promoting a mastery oriented motivational climate in physical education will foster self-determined situational motivation and physical activity.  相似文献   
104.
While the role of the upper torso and pelvis in driving performance is anecdotally appreciated by golf instructors, their actual biomechanical role is unclear. The aims of this study were to describe upper torso and pelvis rotation and velocity during the golf swing and determine their role in ball velocity. One hundred recreational golfers underwent a biomechanical golf swing analysis using their own driver. Upper torso and pelvic rotation and velocity, and torso-pelvic separation and velocity, were measured for each swing. Ball velocity was assessed with a golf launch monitor. Group differences (groups based on ball velocity) and moderate relationships (r > or = 0.50; P < 0.001) were observed between an increase in ball velocity and the following variables: increased torso-pelvic separation at the top of the swing, maximum torso-pelvic separation, maximum upper torso rotation velocity, upper torso rotational velocity at lead arm parallel and last 40 ms before impact, maximum torso-pelvic separation velocity and torso-pelvic separation velocity at both lead arm parallel and at the last 40 ms before impact. Torso-pelvic separation contributes to greater upper torso rotation velocity and torso-pelvic separation velocity during the downswing, ultimately contributing to greater ball velocity. Golf instructors can consider increasing ball velocity by maximizing separation between the upper torso and pelvis at the top of and initiation of the downswing.  相似文献   
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We describe a microfluidic device for on-chip chemical processing, such as staining, and subsequent washing of cells. The paper introduces “separator walls” to increase the on-chip incubation time and to improve the quality of washing. Cells of interest are concentrated into a treatment stream of chemical reagents at the first separator wall for extended on-chip incubation without causing excess contamination at the output due to diffusion of the unreacted treatment chemicals, and then are directed to the washing stream before final collections. The second separator wall further reduces the output contamination from diffusion to the washing stream. With this approach, we demonstrate on-chip leukocyte staining with Rhodamine 6G and washing. The results suggest that other conventional biological and analytical processes could be replaced by the proposed device.  相似文献   
110.
Based on our community engagement project involving 47 older, low-income African-American adults from a senior community center, this study analyzes how an underserved population acquires knowledge and skills related to digital technologies. We discuss the conceptualization, implementation, and evaluation of a weekly, four-month long computer class for members of the senior community center. Our mixed-method research shows the importance of taking into account both the multidimensional nature of adult learning and the social and cultural contexts in which learning occurs when working with underserved adult populations. Findings from our formative and evaluative research offer insights into changes in the computer class participants’ attitudes toward and perspectives on key digital literacy issues including security and privacy online and online information verification. Scholarly and policy implications are discussed in the context of digital competency and adult learning for marginalized populations.  相似文献   
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