Previous research has shown that experts exhibit superior response selection and skill execution during performance in youth sport. The purpose of this study was to examine differences in cognitive and skill execution components of game performance in young baseball players (N = 159) with varying levels of expertise. Three levels of expertise (low-, average-, and high-skilled players) were identified at each age level (7, 8, 9, and 10 years of age). Game performance was videotaped, and measures of skill execution (throwing accuracy, throwing force, fielding, catching, batting average, and batting contact) and cognitive components (positioning, decisions) were developed from observational analysis. The results indicated that baseball skill execution during game play maximally discriminated expertise levels.
The purpose of this study was to examine differences in knowledge representation and problem solutions in expert and novice youth baseball players. Ninety-four players in two age divisions, 7-8 years of age and 9-10 years of age, were assigned to three levels of expertise: high; average; and low skilled. Each subject participated in an interview session to elicit knowledge representation and solutions to five different defensive game situations. Interviews were transcribed and analyzed for content, solution to the problem, errors in problem solution, and qualitative trends. The frequency of advanced solutions to each of the five situations were analyzed in separate chi-square tests for age and expertise. Differences among the levels of expertise were found for the accuracy of solutions to three complex situations. Age was significant for only one situation. Patterns of knowledge content accessed during advanced and less advanced responses indicated both experts and novices were in a beginning stage of developing baseball knowledge structures. Errors in problem solutions indicated children had difficulty monitoring critical conditions and making correct inferences. Players' and teammates' ability to execute baseball skills seemed to influence the content and structure of tactical knowledge accessed during problem solution.
Background Colorectal cancer often presents with obstruction needing urgent, potentially life-saving decompression. The comparative efficacy and safety of endoluminal stenting versus emergency surgery as initial treatment for such patients is uncertain. Methods Patients with left-sided colonic obstruction and radiological features of carcinoma were randomized to endoluminal stenting using a combined endoscopic/fluoroscopic technique followed by elective surgery 1–4 weeks later, or surgical decompression with or without tumour resection. Treatment allocation was via a central randomization service using a minimization procedure stratified by curative intent, primary tumour site, and severity score (Acute Physiology And Chronic Health Evaluation). Co-primary outcome measures were duration of hospital stay and 30-day mortality. Secondary outcomes were stoma formation, stenting completion and complication rates, perioperative morbidity, 6-month survival, 3-year recurrence, resource use, adherence to chemotherapy, and quality of life. Analyses were undertaken by intention to treat. Results Between 23 April 2009 and 22 December 2014, 245 patients from 39 hospitals were randomized. Stenting was attempted in 119 of 123 allocated patients (96.7 per cent), achieving relief of obstruction in 98 of 119 (82.4 per cent). For the 89 per cent treated with curative intent, there were no significant differences in 30-day postoperative mortality (3.6 per cent (4 of 110) versus 5.6 per cent (6 of 107); P = 0.48), or duration of hospital stay (median 19 (i.q.r. 11–34) versus 18 (10–28) days; P = 0.94) between stenting followed by delayed elective surgery and emergency surgery. Among patients undergoing potentially curative treatment, stoma formation occurred less frequently in those allocated to stenting than those allocated to immediate surgery (47 of 99 (47.5 per cent) versus 72 of 106 (67.9 per cent); P = 0.003). There were no significant differences in perioperative morbidity, critical care use, quality of life, 3-year recurrence or mortality between treatment groups. Conclusion Stenting as a bridge to surgery reduces stoma formation without detrimental effects. Registration number: ISRCTN13846816 (http://www.controlled-trials.com).
Stature, sitting height, hip width, arm and calf circumferences and body weight have been measured in black children of Richland County, South Carolina. Lower limb height and three indices of body shape were obtained from the measurements. Sample size exceeded 200 for each of five age-sex groups representing girls and boys aged 6 years, girls and boys aged 9 years, and boys aged 11 years. Comparisons are made with findings from previous research on children of predominantly black ancestry living in west and central Africa, the West Indies, and North, Central and South America. Black children of Richland County measured during 1974--77 are taller than black children studied since 1960 in Angola, Chad, Ghana, Liberia, Nigeria, Senegal, Uganda, Anguilla, Barbados, Cuba, Guyana, Jamaica, Nevis, St. Kitts, St. Vincent, and Surinam. Children of well-to-do black families in Accra and Ibadan are no taller or heavier than black children of Richland County taken without regard to socio-economic status. In hip width, averages for Richland County black children are larger than those for children of the Hutu and Yoruba tribes; in arm girth they are larger than children of the Hutu and Tutsi tribes. Age changes and group differences are reported for hip width relative to lower limb height, and lower limb height relative to sitting height. During childhood, the hip/lower limb index decreases, and the lower limb/sitting height index increases. Almost identical hip/lower limb indices characterize black populations in Africa, Cuba, and the United States.
Somatic data were collected during April 1997 on 156 females ages 6, 9, 13, and 15 years, residing in urban Pusan, South Korea, and on 158 age peers residing in rural regions surrounding the city. Comparisons were made between urban and rural groups for measures of body size and form, skinfold thicknesses, the body mass index (BMI), and estimated arm muscle area (ARM). Age at menarche was retrospectively reported by the 13‐ and 15‐year‐olds. The data were analyzed in 2 (urban‐rural) × 3 (age) analyses of variance with an alpha level of P < 0.05. Age differences were evident for all dimensions. A significant main effect for urban–rural differences was found for stature, lower limb height, upper limb height, shoulder width, hip width, triceps skinfold, ARM, skelic index, and the trunk width index. Regardless of age, urban children were larger than rural children. Similar means were obtained for the BMI in urban and rural girls. Age at menarche was consistent with recent results; however, the rural sample (12.4 years) was significantly earlier than the urban sample (13.1 years). Compared with data collected four decades ago, present‐day 6‐, 9‐, 13‐, and 15‐year‐old females are taller and heavier at every age, indicating secular gains. Pusan females are similar in stature to age peers in Taiwan, Japan, and Hong Kong, and taller than the Chinese. Am. J. Hum. Biol. 11:735–744, 1999. © 1999 Wiley‐Liss, Inc.
Somatic data were collected during July 1995 on 154 males, ages 6, 9, and 15 years, residing in urban Pusan, South Korea, and on 157 age peers residing in rural regions surrounding the city. Comparisons are made between urban and rural groups for measures of body size and form, skinfold thicknesses, the body mass index (BMI), and estimated arm muscle area (ARM). The data were analyzed in 2 (urban‐rural) × 3 (age) analyses of variance with an alpha level of P < 0.05. Age differences were evident for all dimensions. A significant main effect for urban‐rural differences was found for stature, sitting height, lower limb height, upper limb length, arm girth, calf girth, shoulder width, hip width, body weight, and the sum of skinfolds. Regardless of age, urban children were larger than rural children. The interaction was nonsignificant. Except for the trunk width index, urban and rural boys did not differ on measures of body form. Similar means were obtained for the BMI and ARM in urban and rural boys. Compared with data collected four decades ago, present day 6, 9, and 15 year old males are taller and heavier at every age, indicating secular gains. Pusan males are similar in stature to age peers in Taiwan and Japan, and taller than the Chinese. Am. J. Hum. Biol. 9:493–503, 1997. © 1997 Wiley‐Liss, Inc.
Somatic data were collected during September 1991 on 280 males, ages 6, 9, and 15 years, residing in urban St. Petersburg, Russia, and in rural regions surrounding the city. Comparisons are made between urban and rural groups for measures of body size and form, skinfold thicknesses, body mass index (BMI), and estimated arm muscle area (ARM). The data were analyzed in 2 (urban-rural) × 3 (age) analyses of variance, with an alpha level of P < 0.05. Age differences were evident for all measurements. A significant main effect for urban-rural was found for stature, lower limb height, and calf girth; differences approached significance (P < 0.07) for body weight and sitting height. Urban children were larger than rural children in stature, sitting height, lower limb height, calf girth, and body weight. The interaction was nonsignificant. Urban and rural boys did not differ on measures of body form. Similar means were obtained for the sum of skinfolds, the BMI, and ARM in urban and rural boys. Compared with data collected more than a century ago, present-day 15-year-olds are 22 cm taller. It has often been suggested that living in an urban environment provides greater access to the amenities of life than living in a rural area. Although these amenities are difficult to observe differences do exist and the secular trend continues. © 1994 Wiley-Liss, Inc.
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