Kinematic,kinetic and EMG analysis of four front crawl flip turn techniques     

Suzana Matheus Pereira  Caroline Ruschel  Marcel Hubert  Leandro Machado  Helio Roesler  Ricardo Jorge Fernandes 《Journal of sports sciences》2015,33(19):2006-2015

This study aimed to analyse the kinematic, kinetic and electromyographic characteristics of four front crawl flip turn technique variants. The variants distinguished from each other by differences in body position (i.e. dorsal, lateral, ventral) during rolling, wall support, pushing and gliding phases. Seventeen highly trained swimmers (17.9 ± 3.2 years old) participated in interventional sessions and performed three trials of each variant, being monitored with a 3-D video system, a force platform and an electromyography (EMG) system. Studied variables: rolling time and distance, wall support time, push-off time, peak force and horizontal impulse at wall support and push-off, centre of mass horizontal velocity at the end of the push-off, gliding time, centre of mass depth, distance, average and final velocity during gliding, total turn time and electrical activity of Gastrocnemius Medialis, Tibialis Anterior, Biceps Femoris and Vastus Lateralis muscles. Depending on the variant, total turn time ranged from 2.37 ± 0.32 to 2.43 ± 0.33 s, push-off force from 1.86 ± 0.33 to 1.92 ± 0.26 BW and centre of mass velocity during gliding from 1.78 ± 0.21 to 1.94 ± 0.22 m · s^?1. The variants were not distinguishable in terms of kinematical, kinetic and EMG parameters during the rolling, wall support, pushing and gliding phases.  相似文献   

Effects of changing speed on knee and ankle joint load during walking and running     

Ana Cristina de David  Felipe Pivetta Carpes  Darren Stefanyshyn 《Journal of sports sciences》2015,33(4):391-397

Joint moments can be used as an indicator of joint loading and have potential application for sports performance and injury prevention. The effects of changing walking and running speeds on joint moments for the different planes of motion still are debatable. Here, we compared knee and ankle moments during walking and running at different speeds. Data were collected from 11 recreational male runners to determine knee and ankle joint moments during different conditions. Conditions include walking at a comfortable speed (self-selected pacing), fast walking (fastest speed possible), slow running (speed corresponding to 30% slower than running) and running (at 4 m · s^?1 ± 10%). A different joint moment pattern was observed between walking and running. We observed a general increase in joint load for sagittal and frontal planes as speed increased, while the effects of speed were not clear in the transverse plane moments. Although differences tend to be more pronounced when gait changed from walking to running, the peak moments, in general, increased when speed increased from comfortable walking to fast walking and from slow running to running mainly in the sagittal and frontal planes. Knee flexion moment was higher in walking than in running due to larger knee extension. Results suggest caution when recommending walking over running in an attempt to reduce knee joint loading. The different effects of speed increments during walking and running should be considered with regard to the prevention of injuries and for rehabilitation purposes.  相似文献   

Understanding How the Arts Can Enhance Learning     

Susan H. Magsamen  Antonio M. Battro 《Mind, Brain, and Education》2011,5(1):1-2

Understanding how the arts can enhance learning has long been discussed and debated among educators, students, parents, artists, art historians, and philosophers. Many anecdotal examples reference the value and benefits of the arts in a range of fields and learning domains. Emerging methodologies in the brain sciences have added new perspectives and research‐based approaches to better understand the role the arts might play in learning. Psychologists, cognitive scientists, and now neuroscientists are approaching this topic by exploring memory, sensory systems, and other biological measures. The interdisciplinary and potentially interdependence of these fields to work together to identify the neurological mechanisms involved in the arts may offer educators, parents, and child care providers with important information about how we learning takes place. By bringing together uncommon and divergent thinking from a wide range of disciplines, there is an opportunity to change the way we teach, parent, and serve children using the arts to help enhance learning. This issue of Mind, Brain, and Education celebrates the range of approaches that are emerging to shed light and insight in this field.  相似文献   

Infants’ and Young Children's Imitation of Linguistic In‐Group and Out‐Group Informants          下载免费PDF全文

Lauren H. Howard  Annette M. E. Henderson  Cristina Carrazza  Amanda L. Woodward 《Child development》2015,86(1):259-275

Although children can use social categories to intelligently select informants, children's preference for in‐group informants has not been consistently demonstrated across age and context. This research clarifies the extent to which children use social categories to guide learning by presenting participants with a live or video‐recorded action demonstration by a linguistic in‐group and/or out‐group model. Participants’ (N = 104) propensity to imitate these actions was assessed. Nineteen‐month‐olds did not selectively imitate the actions of the in‐group model in live contexts, though in‐group preferences were found after watching the demonstration on video. Three‐year‐olds selectively imitated the actions demonstrated by the in‐group member regardless of context. These results indicate that in‐group preferences have a more nuanced effect on social learning than previous research has indicated.  相似文献   

Individual Differences in Childhood Behavior Disorders Associated With Epigenetic Modulation of the Cortisol Receptor Gene          下载免费PDF全文

Mark R. Dadds  Caroline Moul  David J. Hawes  Antonio Mendoza Diaz  John Brennan 《Child development》2015,86(5):1311-1320

Behavioral/emotional difficulties in children are the first sign of mental health problems. These problems are however, heterogeneous. A domain that may identify homogenous subgroups is hypothalamic–pituitary–adrenal function. This study tested whether epigenetic regulation of glucocorticoid receptor gene could explain the co‐occurrence of anxiety problems in children with behavior problems. Four‐ to 16‐year‐old clinically referred children (N = 241) were measured for psychiatric symptoms, methylation of target CpG sites in blood or saliva, and morning cortisol levels in those who gave blood. Increased methylation of promoter 1F CpG sites was associated with higher vulnerability to co‐occurring internalizing symptoms and morning cortisol. The results support increasing optimism that epigenetic regulation of key neuroendocrine systems might help explain hitherto unfathomable individual differences in susceptibility to psychiatric symptom profiles.  相似文献   

Curriculum studies in Brazil – intellectual histories,present circumstances     

Antonio Flavio Barbosa Moreira 《Compare》2015,45(2):331-334

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Negotiating empire: the cultural politics of schools in Puerto Rico, 1898–1952     

Amílcar Antonio Barreto 《History of education》2015,44(4):529-531

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Student-centred learning and disciplinary enculturation: an exploration through physics     

Cristina Sin 《Educational studies》2015,41(4):351-368

This study argues that student-centred methods in the teaching of physics can be beneficial for students’ enculturation into the discipline and into a physicist’s profession. Interviews conducted with academics and students from six master degrees in physics in three different European countries suggest that student-driven classroom activities, collaborative learning and problem-solving, or integration in research groups/projects enable students to engage in practices similar to those which are part of professional scientists’ routine. Through interactive, participative methods reminiscent of cognitive apprenticeship, students develop a range of abilities necessary in a physicist’s career: capacity of explanation, argumentation and defence of claims; analytical reasoning; capacity to critically review literature; ability to discern research paths worth pursuing; writing skills; and interpersonal skills. These give them a first taste of what it is like to be a physicist and ease their transition into a professional physics career.  相似文献   

Gender differences in adolescents’ choice of heroes and admired adults in five countries     

Juan Diego Estrada  Cristina García-Ael  José Luis Martorell 《Gender and education》2015,27(1):69-87

Seven hundred and sixty-eight adolescents from five countries and regions (USA, Spain, Hong Kong, Qatar, and Malaysia), aged 13–19 (M?=?15.78; SD?=?1.28) years, responded to a questionnaire designed to determine who was their most admired famous adult or hero. Male heroes clearly outnumbered admired females (73.3% vs. 26.7%). There was a pattern of same-sex choices, but it was more likely for girls to choose male heroes than for boys to choose females. Over half of the admired adults were athletes, and movie, television, and music stars. Regarding the personally known adults, there was a more balanced choice of males and females, with parents as the most frequent choice. Results suggest that society continues to fail in providing an adequate supply of female role models.  相似文献   

The Process of Stress Assignment in Reading Aloud: Critical Issues From Studies on Italian     

Simone Sulpizio  Cristina Burani  Lucia Colombo 《Scientific Studies of Reading》2015,19(1):5-20

In polysyllabic languages the assignment of stress is crucial for understanding the reading process. Here we review empirical evidence, drawn mainly from studies on Italian, and discuss critical issues in understanding reading. We first discuss the lexical and sublexical mechanisms responsible for stress assignment and propose that the former is based on item-specific knowledge and the latter on the statistical-distributional knowledge that readers have acquired about their language. Then we examine the idea that stress and phonemes pertain to two dimensions of the word, which can be placed at two different representational levels. Finally, we analyze the effects of stress assignment on word articulation, a promising field for future investigation. These issues are addressed by reviewing the studies conducted in adult and young readers to outline the developmental trajectory of stress assignment and discuss how it operates in the reading system.  相似文献