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51.
Gracia-Marco L Tomas C Vicente-Rodriguez G Jimenez-Pavon D Rey-Lopez JP Ortega FB Lanza-Saiz R Moreno LA 《Journal of sports sciences》2010,28(13):1383-1389
The aims of this study were to identify differences between the sexes in extra-curricular participation in sports and to determine its association with body fat and socio-demographic factors in Spanish adolescents. A total of 2165 adolescents (1124 males and 1041 females) aged 13.0-18.5 years from the AVENA Study participated. Participants filled in an ad hoc questionnaire for extra-curricular participation in sports, which was the dependent variable. Independent variables were: age, percent body fat, and father's and mother's educational level and occupation. Chi-square tests and logistic regression were applied. Bivariate analysis showed for male adolescents that age and father's occupation were related to extra-curricular participation in sports. In addition, body fat and mother's education and occupation (all P?0.05) were related to extra-curricular participation of in sports for female adolescents. Logistic regression analysis showed that the likelihood of involvement in extra-curricular participation in sports was 5.3-fold (3.86-7.38) higher for males than females. Age and father's education in both males and females were independently associated with extra-curricular participation in sports. In summary, Spanish male adolescents were shown to engage in more extra-curricular sports than females. In addition, age and father's education (in both sexes) were associated with the participation of their offspring in extra-curricular sports during adolescence. 相似文献
52.
The Internet has favored the growth of collaborative platforms where marketers and consumers interact to develop more engaging products and services. These platforms are usually centered in a specific brand/product and their members are linked by a shared admiration to that brand. This paper analyzes one of the most powerful online collaborative platforms, the free software (FS) case, which involves a lot of virtual communities developed around products such as Linux or Android, the new Google's mobile operating system. Our purpose is to determine some of the main antecedents and consequences of the consumer involvement in this type of communities. Results have shown that satisfaction with a virtual community may increase the level of consumer participation in that community. At the same time, a greater identification with the virtual community may increase indirectly the consumer participation thanks to the enhancement of his/her satisfaction with the community. We have also found positive and significant effects of consumer identification and participation on the level of community promotion. Finally, positive and significant effects of consumer participation and satisfaction with the community on loyalty to the FS were also found. These findings allow us to conclude some interesting managerial implications. 相似文献
53.
Learning science through research apprenticeships: A critical review of the literature 总被引:1,自引:0,他引:1
Science education models for secondary and college students as well as K‐12 teachers have been dominated by classroom‐based approaches. Recently, research apprenticeships wherein learners worked with practicing scientists on authentic scientific research have become increasingly popular. The purpose of this critical review of the literature was to review and synthesize empirical studies that have explored learning outcomes associated with research apprenticeships for science learners. We reviewed 53 studies of scientific research apprenticeship experiences for secondary students, undergraduates and teachers, both pre‐service and in‐service. The review explored various learning outcomes associated with participation in research apprenticeships. These outcomes included effects of apprenticeship experiences on participant career aspirations, ideas about the nature of science (NOS), understandings of scientific content, confidence for doing science and intellectual development. The extant literature supported many of the presumed positive associations between apprenticeship experiences and desired learning outcomes, but findings related to some themes (e.g., NOS understandings) supported conflicting conclusions. Implications included importance of the length of the apprenticeship, need to explicitly place attention on desired outcomes, and engagement of participants. © 2009 Wiley Periodicals, Inc. J Res Sci Teach 47:235–256, 2010 相似文献
54.
Luis Enrique Valdez-Juárez Omar Javier Solano-Rodríguez Dominique Philippe Martin 《The Journal of High Technology Management Research》2018,29(2):193-203
The aim of this study is to analyze the effects of different modes of learning on innovation and profitability in SMEs in two Latin American countries; Mexico and Colombia. The data were obtained using a sample of 250 companies in the industrial sector operating in both countries. Results show that an integrated mode of learning based on internal and external knowledge supported by technological infrastructure have positive and significant effects on the degree of innovation and the profitability in SMEs However this effect appears to be not significantly different from the traditional SMEs mode of learning based mainly on market orientation. 相似文献
55.
Alejandro Gomez-Bruton Jesús Montero-Marín Alejandro González-Agüero Alba Gómez-Cabello Javier García-Campayo Luis A. Moreno 《Journal of sports sciences》2018,36(4):365-377
This meta-analysis aims to determine the effects of regular swimming on bone mineral density (BMD) in young adults (18–30 years). A systematic search was performed in Pubmed, SPORTDiscus and the Cochrane Library from the earliest possible year to March 2016. Swimmers were compared to non-athletic controls (CG) and to high-impact athletes (HIGH). Effect sizes with the Hedges g in random effects models were developed. Fourteen studies met the inclusion criteria and were included in the meta-analyses. Swimmers presented similar BMD values to CG in whole-body (g = ?0.20; P = 0.251), femoral neck (g = ?0.05; P = 0.818) and lumbar spine (g = 0.18; P = 0.492); and lower BMD in the whole-body (g = ?1.21; P < 0.001), femoral neck (g = ?1.51; P < 0.001) and lumbar spine (g = ?0.84; P = 0.017) than the HIGH. For the whole-body differences, the higher the latitude the smaller the differences between swimmers and HIGH (B = 0.10; P = 0.001). For the femoral neck differences, age also seemed to reduce the differences between groups (B = 0.19; P = 0.020). Young adult swimmers present similar BMD values than CG and lower values than HIGH. 相似文献
56.
Manuel TORAL IBAEZ 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)
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-Viilarrica,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,BF 12,BF13,and BF 14) 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. 相似文献
57.
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
58.
Luis Augusto Teixeira Elke Dos Santos Lima Mariana Marília Franzoni 《Journal of sports sciences》2013,31(9):943-950
The time course of movement timing reprogramming was examined in a task requiring temporal coincidence of the conclusion of a forehand drive with the arrival of a moving luminous target at the end of an electronic trackway. The moving target departed from one end of the trackway at a constant velocity of 2?m . s?1, and for a part of the trials its velocity was increased to 3?m . s?1. Target velocity was modified at different moments during stimulus displacement, producing times-to-arrival after velocity increment (TAVIs) from 100 to 600?ms. The effect of specific practice on movement reprogramming was also examined. The results showed early adjustments to the action (TAVIs = 100?–?200?ms) that seemed to be stereotyped, while feedback-based corrections were implemented only at TAVIs of 300?ms or longer. Temporal accuracy was progressively increased as longer TAVIs were provided up to 600?ms. Skill training led to an overall increment of temporal accuracy, but no effect of specific practice was found. The results indicate that timing reprogramming in interceptive actions is a continuous process limited mainly by intrinsic factors: latency to initiate more effective adjustments to the action, and rate-of-movement timing reprogramming. 相似文献
59.
Pedro Passos Duarte Araújo Keith Davids Luis Gouveia João Milho SidóNio Serpa 《Journal of sports sciences》2013,31(13):1421-1429
Abstract Previous work on dynamics of interpersonal interactions in 1 vs. 1 sub-phases of basketball has identified changes in interpersonal distance between an attacker and defender as a potential control parameter for influencing organizational states of attacker–defender dyads. Other studies have reported the constraining effect of relative velocity between an attacker and defender in 1 vs. 1 dyads. To evaluate the relationship between these candidate control parameters, we compared the impact of both interpersonal distance and relative velocity on the pattern-forming dynamics of attacker–defender dyads in the sport of rugby union. Results revealed that when interpersonal distance achieved a critical value of less than 4 m, and relative velocity values increased or were maintained above 1 m · s?1, a successful outcome (i.e. clean attempt) for an attacker was predicted. Alternatively, when values of relative velocity suddenly decreased below this threshold, at the same critical value of interpersonal distance, a successful outcome for the defender was predicted. Data demonstrated how the coupling of these two potential, nested control parameters moved the dyadic system to phase transitions, characterized as a try or a tackle. Observations suggested that relative velocity increased its influence on the organization of attacker–defender dyads in rugby union over time as spatial proximity to the try line increased. 相似文献
60.
Luis Calmeiro Gershon Tenenbaum David William Eccles 《Journal of sports sciences》2013,31(19):1813-1820
AbstractThe purpose of this study was to compare moment-to-moment appraisals and coping strategies of 4 non-elite and 2 elite male trap shooters during competitions and in particular during periods of competition perceived as critical to performance. Appraisals and coping patterns of trap shooters were captured via verbal reports of thinking provided between sets of shots during major competitions. Verbal reports were coded according to an appraisal and coping typology. Coded data as well as shooting performance data were subjected to a sequential analysis of probabilities of pairs of events. Fewer reports of negative appraisals (NEGAs) and more frequent reports of problem-focused coping (PFC) were observed among both elite athletes compared to non-elite athletes. After making a NEGA, non-elite shooters often progressed to the next target without attempting to cope, whereas elite shooters used both PFC and emotion-focused coping (EFC) before proceeding to the next target. After missing a target, the non-elite athletes used more EFC than expected. These results indicate that elite athletes are more likely to cope with NEGAs than non-elite athletes using a wider variety of coping strategies. Athletes might benefit from increased awareness of the potentially detrimental impact of NEGAs on performance and by integrating coping strategies within preparatory routines. 相似文献