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排序方式: 共有346条查询结果,搜索用时 15 毫秒
31.
Marc F. Moreira Jorge E. Morais Daniel A. Marinho António J. Silva Tiago M. Barbosa 《Sports biomechanics / International Society of Biomechanics in Sports》2014,13(1):62-74
This study aimed to analyse the effect of growth during a summer break on biomechanical profile of talented swimmers. Twenty-five young swimmers (12 boys and 13 girls) undertook several anthropometric and biomechanical tests at the end of the 2011–2012 season (pre-test) and 10 weeks later at the beginning of the 2012–2013 season (post-test). Height, arm span, hand surface area, and foot surface area were collected as anthropometric parameters, while stroke frequency, stroke length, stroke index, propelling efficiency, active drag, and active drag coefficient were considered as biomechanical variables. The mean swimming velocity during an all-out 25 m front crawl effort was used as the performance outcome. After the 10-week break, the swimmers were taller with an increased arm span, hand, and foot areas. Increases in stroke length, stroke index, propelling efficiency, and performance were also observed. Conversely, the stroke frequency, active drag, and drag coefficient remained unchanged. When controlling the effect of growth, no significant variation was determined on the biomechanical variables. The performance presented high associations with biomechanical and anthropometric parameters at pre-test and post-test, respectively. The results show that young talented swimmers still present biomechanical improvements after a 10-week break, which are mainly explained by their normal growth. 相似文献
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Benjamin Gonzalez O’Brien Elizabeth Hurst Loren Collingwood 《Mass Communication and Society》2019,22(6):756-778
The refugee sanctuary movement in the United States has shifted to include undocumented immigrants fleeing violence and economic strife. Given the negative tenor of coverage of undocumented immigration, and ties between framing and policy views on immigration, how the media frames sanctuary cities is likely to impact public perceptions of these cities and their policies. To assess media coverage of sanctuary policies, we analyzed articles from five national newspapers from 1980 to 2017 with both human content analysis and dictionary-based computational analysis. We find that framing around religion/morality and conflict has decreased, while stories focusing on crime and partisanship have increased. We discuss implications for public opinion and the likelihood that the American public will take their cues from media framing and elite discourse when it comes to sanctuary policies. 相似文献
34.
Jorge Feijoo Xosé Ramón Nóvoa Teresa Rivas María Jesús Mosquera Javier Taboada Cristina Montojo Fernando Carrera 《Journal of Cultural Heritage》2013,14(5):365-376
We describe the results of electromigration desalination of two soluble salt-contaminated Galician granites. The efficacy of electromigration, which had not been previously applied to granite, was assessed for two types of granite contaminated with a 20% NaCl solution and seawater. Desalination effectiveness was evaluated as follows: (1) analysis of anode and cathode ion content during testing; (2) analysis of ions at different distances from the electrodes after testing; (3) pH assessment of the stone surfaces; and (4) evaluation of colour changes. Results were very satisfactory; by the end of testing, chloride was reduced by almost 100% in both the NaCl and seawater contaminated samples. Sulfate reduction was also significant, despite this ion's lower mobility. The granite pH values remained close to neutral and colour changes were minimal. The difference in effectiveness of the process for the two types of stone was associated with their dissimilar pore structure. 相似文献
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Machado-Rodrigues AM Coelho-E-Silva MJ Mota J Cyrino E Cumming SP Riddoch C Beunen G Malina RM 《Journal of sports sciences》2011,29(14):1503-1514
The agreement between self-reported and objective estimates of activity energy expenditure was evaluated in adolescents by age, sex, and weight status. Altogether, 403 participants (217 females, 186 males) aged 13-16 years completed a 3-day physical activity diary and wore a GT1M accelerometer on the same days. Partial correlations (controlling for body mass) were used to determine associations between estimated activity energy expenditure (kcal · min(-1)) from the diary and accelerometry. Differences in the magnitude of the correlations were examined using Fisher's r to z transformations. Bland-Altman procedures were used to determine concordance between the self-reported and objective estimates. Partial correlations between assessments of activity energy expenditure (kcal · min(-1)) did not differ significantly by age (13-14 years: r = 0.41; 15-16 years: r = 0.42) or weight status (normal weight: r = 0.42; overweight: r = 0.39). The magnitude of the association was significantly affected by sex (Δr = 0.11; P < 0.05). The agreement was significantly higher in males than in females. The relationship between activity energy expenditure assessed by the objective method and the 3-day diary was moderate (controlling for weight, correlations ranged between 0.33 and 0.44). However, the 3-day diary revealed less agreement in specific group analyses; it markedly underestimated activity energy expenditure in overweight/obese and older adolescents. The assessment of activity energy expenditure is complex and may require a combination of methods. 相似文献
38.
Manuel Toral Ibañez Margarita Caru Miguel A. Herrera Luis Gonzalez Luis M. Martin Jorge Miranda Rafael M. Navarro-Cerrillo 《Journal of Zhejiang University. Science. B》2009,10(2):112-119
A protocol of polymerase chain reaction-random amplified polymorphic DNAs (PCR-RAPDs) was established to analyse the gene
diversity and genotype identification for clones of Sequoia sempervirens (D. Don) Endl. in Chile. Ten (out of 34) clones from introduction trial located in Voipir-Villarrica, Chile, were studied.
The PCR-RAPDs technique and a modified hexadecyltrimethylammonium bromide (CTAB) protocol were used for genomic DNA extraction.
The PCR tests were carried out employing 10-mer random primers. The amplification products were detected by electrophoresis
in agarose gels. Forty nine polymorphic bands were obtained with the selected primers (BG04, BF07, BF12, BF13, and BF14) and
were ordered according to their molecular size. The genetic similarity between samples was calculated by the Jaccard index
and a dendrogram was constructed using a cluster analysis of unweighted pair group method using arithmetic averages (UPGMA).
Of the primers tested, 5 (out of 60) RAPD primers were selected for their reproducibility and high polymorphism. A total of
49 polymorphic RAPD bands were detected out of 252 bands. The genetic similarity analysis demonstrates an extensive genetic
variability between the tested clones and the dendrogram depicts the genetic relationships among the clones, suggesting a
geographic relationship. The results indicate that the RAPD markers permitted the identification of the assayed clones, although
they are derived from the same geographic origin.
Project (No. CONICYT-FONDEF PROYECT D01 I 1008) supported by the National Commission of Science and Research of Chile 相似文献
39.
Abstract The aim of this study was to examine the effect of positioning on the correctness of decision making of top-class referees and assistant referees during international games. Match analyses were carried out during the Fédération Internationale de Football Association (FIFA) Confederations Cup 2009 and 380 foul play incidents and 165 offside situations were examined. The error percentage for the referees when indicating the incidents averaged 14%. The lowest error percentage occurred in the central area of the field, where the collaboration of the assistant referee is limited, and was achieved when indicating the incidents from a distance of 11-15?m, whereas this percentage peaked (23%) in the last 15-min match period. The error rate for the assistant referees was 13%. Distance of the assistant referee to the offside line did not have an impact on the quality of the offside decision. The risk of making incorrect decisions was reduced when the assistant referees viewed the offside situations from an angle between 46 and 60°. Incorrect offside decisions occurred twice as often in the second as in the first half of the games. Perceptual-cognitive training sessions specific to the requirements of the game should be implemented in the weekly schedule of football officials to reduce the overall error rate. 相似文献
40.
Educating English language learners (ELLs) presents a challenge for teachers and policy makers; the population of ELLs increases, yet their achievement trails that of their native English-speaking peers. In November 2002, Massachusetts voters supported a law that mandated Sheltered English Immersion (SEI) as the primary means of instruction for ELLs, effectively ending transitional bilingual education. This report examines key considerations in educating ELLs, and in implementing SEI in Massachusetts schools. It also presents case studies of three schools making significant strides with ELLs through innovative programming built around SEI methods yet maintaining important bilingual education practices that promote educational equity. Cross-case analysis identified themes about strategic data use, staff recruitment, and supports for students and families. 相似文献