Effects of Participation in a Summer Sports Camp on At-Risk Boys: A Self-Determination Theory Perspective

Summer camps have received recent attention as an intervention to increase adolescents’ physical activity. To date, research has rarely focused how a summer camp influences at-risk boys’ motivation and physical activity through a self-determination theory. The purpose of this study was to examine changes of motivational and physical measures for at-risk boys participating in a summer sports camp. This study also investigated whether initiative games provide instructor support for autonomy, competence, and relatedness for at-risk boys. One hundred at-risk boys, aged 10-13 years, participated in a summer sports camp located in southwest U.S. for three weeks. The boys participated in scheduled camp activities on daily basis during the three-week camp period. Three motivational measure questionnaires (Psychological Needs Perception; Behavioral Regulation in Exercise Questionnaire II – BREQ II; Perceived Instructor Support) and PACER (Progressive Aerobic Cardiovascular Endurance Run) test were completed by the boys at the beginning of camp as pre-test and then, at the end of camp, the boys completed all the measures in the same manner again as post-test. In addition, fifty boys who participated in the initiative games were interviewed about perceptions of instructor support for autonomy, competence, and relatedness and observations were conducted to collect instructor’s supportive behaviors for autonomy, competence, and relatedness during initiative games. Results revealed the boys’ amotivation increased and their intrinsic regulation decreased across the camp period. The boys’ PACER test scores showed no significant changes across the two different time periods. Further, the boys perceived the instructor’s supportive behaviors (i.e., autonomy, competence, and relatedness support) during the initiative games. The findings suggest programs that allow more camper-centered options and de-emphasize competition may promote increased motivation and physical activity of at-risk boys through better meeting their needs

An investigation of voids formation mechanisms and their effects on freeze and thaw processes of lithium and lithium fluoride

The mechanisms of void formation during the cooldown and freezing of lithium coolant within the primary loop of SP-100 type systems are investigated. These mechanisms are: (1) homogeneous nucleation; (2) heterogeneous nucleation; (3) normal segregation of helium gas dissolved in liquid lithium; and (4) shrinkage of lithium during freezing. To evaluate the void formation potential due to segregation, a numerical scheme that couples the freezing and mass diffusion processes in both the solid and liquid regions is developed. The results indicated that the formation of He bubbles is unlikely by either homogeneous or heterogeneous nucleation during the cooldown process. However, homogeneous nucleation of He bubbles following the segregation of dissolved He in liquid lithium ahead of the solid-liquid interface is likely to occur. Results also show that total volume of He void is insignificant when compared to that of shrinkage voids. In viewing this, the subsequent research focuses on the effects of shrinkage void forming during freezing of lithium on subsequent thaw processes are investigated using a numerical scheme that is based on a single (solid/liquid) cell approach. The cases of lithium-fluoride are also investigated to show the effect of larger volume shrinkage upon freezing on the freeze and thaw processes. Results show that a void forming at the wall appreciably reduces the solid-liquid interface velocity, during both freeze and thaw, and causes a substantial rise in the wall temperature during thaw. However, in the case of Li, the maximum wall temperature was much lower than the melting temperature of PWC-11, which is used as the structure material in the SP-100 system. Hence, it is included that a formation of hot spots is unlikely during the startup or restart of the SP-100 system

Epidural cement leakage through pedicle violation after balloon kyphoplasty causing paraparesis in osteoporotic vertebral compression fractures - a report of two cases

Kyphoplasty is advantageous over vertebroplasty in terms of better kyphosis correction and diminished risk of cement extravasations. Literature described cement leakage causing neurological injury mainly after vertebroplasty procedure; only a few case reports show cement leakage with kyphoplasty without neurological injury or proper cause of leakage. We present a report two cases of osteoporotic vertebral compression fracture treated with kyphoplasty and developed cement leakage causing significant neurological injury. In both cases CT scan was the diagnostic tool to identify cause of cement leakage. CT scan exhibited violation of medial pedicle wall causing cement leakage in the spinal canal. Both patients displayed clinical improvement after decompression surgery with or without instrumentation. Retrospectively looking at stored fluoroscopic images, we found that improper position of trocar in AP and lateral view simultaneously while taking entry caused pedicle wall violation. We suggest not to cross medial pedicle wall in AP image throughout the entire procedure and keeping the trocar in the center of pedicle in lateral image would be the most important precaution to prevent such complication. Our case reports adds the neurological complications with kyphoplasty procedure and suggested that along with other precautions described in the literature, entry with trocar along the entire procedure keeping the oval shape of pedicle in mind (under C-arm) will probably help to prevent such complications