Swimming and peak bone mineral density: A systematic review and meta-analysis     

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   

Intellectual capital of nations: a comparative analysis of assessment models     

Romilio?LabraEmail author  Ma?Paloma?Sánchez 《知识管理研究与实践》2017,15(2):169-183

Although intellectual capital (IC) is the most important factor determining the economic growth, the literature on country-level IC is not quite enough, and more advances are required to improve the assistance to policy makers in the knowledge era. There are different approaches to measuring and managing intangibles, which opens research opportunities and offers new tools to manage IC. This paper contributes to identify, select, and classify models to evaluate and manage intangibles at the country level. The models were identified through a systematic literature review. They were analyzed and compared using cluster analysis. The results show that the models can be grouped into two main categories according to origin and structure. Despite the differences among the models, the reports tend to converge, because of which the decision about which model to choose can be based on pragmatic issues, such as availability of data, previous knowledge, and complexity of reports.  相似文献   

Motivation and Exercise Dependence     

David González-Cutre  Álvaro Sicilia 《Research quarterly for exercise and sport》2013,84(2):318-329

The objective of this study was to use self-determination theory to analyze the relationships of several motivational variables with exercise dependence. The study involved 531 exercisers, ranging in age from 16 to 60 years old, who responded to different questionnaires assessing perception of motivational climate, satisfaction of basic psychological needs, motivation types, and exercise dependence. The results of multiple mediation analysis revealed that ego-involving climate and perceived competence positively predicted exercise dependence in a directed and mediated manner through introjected and external regulation. Gender and age did not moderate the analyzed relationships. These results allow us to better understand the motivational process explaining exercise dependence, demonstrating the negative influence of the ego-involving climate in the context of exercise.  相似文献   

Comparison of different theoretical models estimating peak power output and maximal oxygen uptake in trained and elite triathletes and endurance cyclists in the velodrome     

Carlos González-Haro  Pedro A. Galilea  Jesús F. Escanero 《Journal of sports sciences》2013,31(6):591-601

Abstract

The primary objective of this study was to examine the relationship between heart rate intensity and pedometer step counts in adolescents. To determine cardiorespiratory fitness, 106 participants (47 boys, 59 girls, mean age 14.2 years, s = 0.8) completed the Queen's College Step Test and were classified as having low, moderate or high cardiorespiratory fitness. Adolescents also completed a 10-min treadmill trial while wearing a pedometer and heart rate monitor. The participants were instructed to maintain their heart rate between 65 and 75% of their maximum heart rate while running or walking on a treadmill. A heart rate of 65–75% maximum was associated with 146 steps per minute (s = 22) in boys and 137 steps per minute (s = 22) in girls. Results of analysis of variance indicated that there was a main effect for level of fitness (F _2,102 = 9.36, P < 0.001). The correlation between mean steps per minute and estimated maximum oxygen consumption was statistically significant (r = 0.44, P < 0.001). The results from this study suggest that a step rate of 130 steps per minute is equal to 65–75% maximum heart rate in low-fit adolescents and achieving 130 steps per minute could be used as an initial goal to improve fitness.  相似文献   

Generalized multistable structure via chaotic synchronization and preservation of scrolls     

E. Jiménez-López  J.S. González Salas  L.J. Ontañón-García  E. Campos-Cantón  A.N. Pisarchik 《Journal of The Franklin Institute》2013,350(10):2853-2866

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The role of habituation of the response to LiCl in the US-preexposure effect     

de Brugada I  González F  Gil M  Hall G 《Learning & behavior》2005,33(3):363-370

In two experiments, rats received preexposure consisting of six intraperitoneal injections of lithium chloride (LiCl). This treatment reduced the magnitude of the unconditioned response (UR; suppressed consumption of a novel flavor) evoked by an additional injection (Experiment 1) or by oral consumption (Experiment 2) of LiCl. In both experiments, preexposure also attenuated the acquisition of a conditioned aversion with an LiCl injection as the unconditioned stimulus (US) but had no effect on the aversion produced when the US was oral consumption of LiCl (Experiment 2). These results are consistent with the view that the reduced ability of the preexposed US to serve as a reinforcer depends on blocking by injection-related cues and is independent of habituation of the UR recorded in the present study. Possible interpretations of this dissociation are discussed.  相似文献   

Incompatibility between pregnancy and educational projects,from the perspective of socially vulnerable adolescent women and men in Mexico     

Lourdes Campero  Alejandra Benítez  Erika Atienzo  Guillermo González  Eréndira Marín 《Gender and education》2014,26(2):151-167

Research focused on adolescent pregnancy reports that this event acquires significance and has different consequences according to the context and social subjects who experience it. In this study, by means of a sample formed by adolescent women and men who are socially vulnerable in Mexico, with and without a history of pregnancy, we can see how this reproductive event turns into a factor of educational vulnerability and how their possibilities and expectations with respect to continuing in school are determined in a differentiated manner, according to gender. The findings show that adolescent pregnancy in vulnerable sectors is scarcely compatible with educational projects and that possibilities and expectations to continue in or re-enter the school system are determined by gender differences; these usually lead to fewer opportunities for adolescent women to return to school during or after pregnancy.  相似文献   

Stuck Behind the Curve: How the Academic Law Library Can Help Students Who Struggle in Law School     

Jennifer A. González 《Legal Reference Services Quarterly》2013,32(3):239-268

This article examines how academic law libraries can assist law schools in meeting the needs of students who struggle in law school. This article will describe the types of programs currently available to help struggling students within law schools, including academic support programs, and offer suggestions to improve the delivery of services to this growing population.  相似文献   

Turkish Prospective Chemistry Teachers’ Beliefs about Chemistry Teaching     

F. Javier Perales‐Palacios  José M. Vílchez‐González 《International Journal of Science Education》2013,35(14):1647-1670

Given the progressive loss of influence for the school relative to television in youngsters’ everyday lives, this article describes the procedure and the results of including cartoons in the physics curriculum in secondary education. Work was carried out intensively with a small group of pupils and sporadically with a larger group. In the first case, cartoons were used for identifying and discussing fictitious phenomena, problem‐solving, and assessment of the learning. In the second case, for identifying and discussing fictitious phenomena, a quasi‐experimental research design was followed. The results back the use of this didactic tool as an element for motivating and invigorating the classroom, for identifying the pupils’ alternative ideas and the assessment of their learning, as well as for a more critical way of watching television.  相似文献   

‘Does it answer the question or is it French fries?’: an exploration of language supports for scientific argumentation     

María González-Howard  Katherine L. McNeill  Lisa M. Marco-Bujosa  C. Patrick Proctor 《International Journal of Science Education》2013,35(5):528-547

ABSTRACT

Reform initiatives around the world are reconceptualising science education by stressing student engagement in science practices. Yet, science practices are language-intensive, requiring students to have strong receptive and productive language proficiencies. It is critical to address these rigorous language demands to ensure equitable learning opportunities for all students, including English language learners (ELLs). Little research has examined how to specifically support ELL students’ engagement in science practices, such as argumentation. Using case-study methodology, we examined one middle school science teacher's instructional strategies as she taught an argumentation-focused curriculum in a self-contained ELL classroom. Findings revealed that three trends characterized the teacher’s language supports for the structural and dialogic components of argumentation: (1) more language supports focused on argument structure, (2) dialogic interactions were most often facilitated by productive language supports, and (3) some language supports offered a rationale for argumentation. Findings suggest a need to identify and develop supports for the dialogic aspects of argumentation. Furthermore, engaging students in argumentation through productive language functions could be leveraged to support dialogic interactions. Lastly, our work points to the need for language supports that make the rationale for argumentation explicit since such transparency could further increase access for all students.  相似文献