The effects of maturation on jumping ability and sprint adaptations to plyometric training in youth soccer players     

Abbas Asadi  Rodrigo Ramirez-Campillo  Hamid Arazi 《Journal of sports sciences》2018,36(21):2405-2411

The aim of this study was to investigate the effects of maturation on power and sprint performance adaptations following 6 weeks of plyometric training in youth soccer players during pre-season. Sixty male soccer players were categorized into 3 maturity groups (Pre, Mid and Post peak height velocity [PHV]) and then randomly assigned to plyometric group and control group. Vertical jump, standing long jump, and 20-m sprint (with and without ball) tests were collected before- and after-intervention. After the intervention, the Pre, Mid and Post-PHV groups showed significant (P ≤ 0.05) and small to moderate effect size (ES) improvement in vertical jump (ES = 0.48; 0.57; 0.73), peak power output (E = 0.60; 0.64; 0.76), standing long jump (ES = 0.62; 0.65; 0.7), 20-m sprint (ES = ?0.58; ?0.66), and 20-m sprint with ball (ES = ?0.44; ?0.8; ?0.55) performances. The Post-PHV soccer players indicated greater gains than Pre-PHV in vertical jump and sprint performance after training (P ≤ 0.05). Short-term plyometric training had positive effects on sprinting and jumping-power which are important determinants of match-winning actions in soccer. These results indicate that a sixty foot contact, twice per week program, seems effective in improving power and sprint performance in youth soccer players.  相似文献   

Antecedents of continued use intention of e-hailing apps from the passengers' perspective     

Luiz Antonio Joia  Diego Altieri 《The Journal of High Technology Management Research》2018,29(2):204-215

E-Hailing Apps (EHA) – mobile device software to order any form of transportation pick up – have become very popular in society due to the swift proliferation of smartphones worldwide. Thus, the scope of this article is to ascertain the antecedents of continued use intention of EHA from the passengers' standpoint. To achieve this, a meta-model was developed via a theoretical background based on theories of information system adoption, diffusion of innovation, trust in virtual environments and user satisfaction, as well as research hypotheses. By applying structural equation modelling in data collected via a web survey, the theoretical meta-model and research hypotheses were tested. It was established that perceived utility, compatibility, relative advantage and trust are antecedents of user satisfaction with EHA, this factor being an antecedent of the continued use intention of same. Lastly, it was found that subjective norms have a direct and statistically significant impact on the continued use intention of EHA.  相似文献   

From closed source to open source software: Analysis of the migration process to Open Office     

Luiz Antonio Joia  José Carlos dos Santos Vinhais 《The Journal of High Technology Management Research》2017,28(2):261-272

This article seeks to analyse the migration trajectory from commercial off-the-shelf and closed source software to open source software in order to establish the critical success/resistance factors associated with the replacement of the extant Microsoft Office with Open Office software in a private Brazilian company. The bibliographical review of this work addresses adoption/resistance to information systems, which is the theoretical framework adopted to explain the data collected. The single case study method was then applied and data was collected via documentation analysis, interviews, questionnaires, and direct and participant observation. Data analysis was then conducted by means of content analysis and non-parametric statistics. Based on that, three types of user behaviour were identified with respect to the intention to use open source software, namely adopters, partial adopters, and non-adopters. Finally, the reasons for such behaviour were set forth and discussed in order to make the implications of the study clear.  相似文献   

Burning a Candle in a Vessel, a Simple Experiment with a Long History     

Francisco Vera  Rodrigo Rivera  César Nú?ez 《Science & Education》2011,20(9):881-893

The experiment in which a candle is burned inside an inverted vessel partially immersed in water has a history of more than 2,200 years, but even nowadays it is common that students and teachers relate the change in volume of the enclosed air to its oxygen content. Contrary to what many people think, Lavoisier concluded that any change in volume in this experiment is negligible; moreover, the explanation relating oxygen consumption in the air with its change in volume is known to be wrong. In this work we briefly review the history behind the candle experiment and its relationship with some typical erroneous explanations. One of the key factors behind Lavoisier’s success was the use of experiments carefully designed to test different hypotheses. Following these steps, we performed several closed volume experiments where the candle wick was replaced by a capillary stainless steel cylinder supported and heated by a nichrome filament connected to an external power supply. Our recorded experiments are displayed as web pages, designed with the purpose that the reader can easily visualize and analyze modern versions of Lavoisier’s experiments. These experiments clearly show an initial phase of complete combustion, followed by a phase of incomplete combustion with elemental carbon or soot rising to the top of the vessel, and a final phase where the hot artificial wick only evaporates a white steam of wax that cannot ignite because no oxygen is left in the closed atmosphere. After either a complete or incomplete combustion of the oxygen, our experiments show that the final gas volume is nearly equal to the initial air volume.  相似文献   

The influence of the family educational scenario on internet use of primary and secondary school children / La influencia del escenario educativo familiar en el uso de internet en los niños de primaria y secundaria     

Sonia Padilla  Elisa Rodríguez  Míriam Álvarez  Alezandra Torres  Arminda Suárez  María-José Rodrigo 《Infancia y Aprendizaje》2015,38(2):402-434

Abstract

With the aim of studying the impact of the internet in the home, this paper analyses how the physical component (where and with whom) and attitudinal component (who decides what the child is to see on the internet and motivations for internet use) of the family educational scenario influence the frequency of internet use and diversity of uses, as reported by parents. The participants included 711 parents of children in primary and secondary school. Results showed that being in secondary school, using the internet in privacy at home, without company, internet content under the child’s control, and parental motivations based on the internet being used as a means for the child to relax, predicted higher frequency of internet use. Some of these factors, as well as the presence of peers and new parental attitudes related to the use of the internet for social and learning purposes, predicted a greater variety of uses, suggesting a more appropriate family scenario. The practical implications for parental education on this matter are described.  相似文献   

Perspectives on the Origins of Life in Science Textbooks from a Christian Publisher: Implications for Teaching Science     

Baptista  Geilsa Costa Santos  Santos  Rodrigo da Silva  Cobern  William W. 《International Journal of Science and Mathematics Education》2015,13(2):309-329

This study analyzes six seventh grade Israeli mathematics textbooks, examining (1) the extent to which students are required to justify and explain their mathematical work, and (2) whether students are asked to justify a mathematical claim that is stated by the textbook or a mathematical claim that they themselves generated when solving a problem. Two different units of analysis were used to analyze two central topics in the seventh grade curriculum as follows: (1) equation solving in algebra and (2) triangle properties in geometry. The findings indicate that all six textbooks had considerably larger percentages of geometric tasks than algebraic tasks, which required students to justify or explain their mathematical work. Moreover, considerable differences were found among the six textbooks regarding the percentages of tasks that required students to justify and explain in both topics, but more so with the algebraic topic. Analysis of whether the textbook tasks required students to justify a mathematical claim that is stated by the textbook or a mathematical claim that the students themselves generated also revealed substantial differences among the textbooks. These findings are discussed, as well as the research methods used, in light of relevant literature.  相似文献   

Mexican Educators Survey on Anatomical Sciences Education and a Review of World Tendencies     

Yolanda Salinas-Alvarez  Alejandro Quiroga-Garza  Javier Humberto Martinez-Garza  Guillermo Jacobo-Baca  Pablo Patricio Zarate-Garza  Karla Valeria Rodríguez-Alanís  Santos Guzman-Lopez  Rodrigo Enrique Elizondo-Omaña 《Anatomical sciences education》2021,14(4):471-481

Anatomical sciences curricula have been under constant reform over the years, with many countries having to reduce course hours while trying to preserve laboratory time. In Mexico, schools have historically been autonomous and unregulated, and data regarding structure and methods are still lacking. A national survey was sent by the Mexican Society of Anatomy to 110 anatomical sciences educators. The questionnaire consisted of 50 items (open and multiple choice) for gross anatomy, microscopic anatomy, neuroanatomy, and embryology courses in medical schools across Mexico. A clinical approach was the most common course approach in all disciplines. Contact course hours and laboratory hours were higher in Mexican anatomy education compared to other countries, with the highest reported contact hours for embryology (133.4 ± 44.1) and histology (125 ± 33.2). There were similar contact hours to other countries for gross anatomy (228.5 ± 60.5). Neuroanatomy course hours (43.9 ± 13.1) were less than reported by the United States and similar to Saudi Arabia and higher than the United Kingdom. Dissection and microscopy with histological slides predominate as the most common laboratory activities. Traditional methods prevail in most of the courses in Mexico and only a few educators have implemented innovative and technological tools. Implementation of new methods, approaches, and curricular changes are needed to enhance anatomical sciences education in Mexico.  相似文献   

Kinetics and kinematics analysis of incremental cycling to exhaustion   总被引：1，自引：0，他引：1  

Bini RR  Diefenthaeler F 《Sports biomechanics / International Society of Biomechanics in Sports》2010,9(4):223-235

Technique changes in cyclists are not well described during exhaustive exercise. Therefore the aim of the present study was to analyze pedaling technique during an incremental cycling test to exhaustion. Eleven cyclists performed an incremental cycling test to exhaustion. Pedal force and joint kinematics were acquired during the last three stages of the test (75%, 90% and 100% of the maximal power output). Inverse dynamics was conducted to calculate the net joint moments at the hip, knee and ankle joints. Knee joint had an increased contribution to the total net joint moments with the increase of workload (5-8% increase, p < 0.01). Total average absolute joint moment and knee joint moment increased during the test (25% and 39%, for p < 0.01, respectively). Increases in plantar flexor moment (32%, p < 0.01), knee (54%, p < 0.01) and hip flexor moments (42%, p = 0.02) were found. Higher dorsiflexion (2%, for p = 0.03) and increased range of motion (19%, for p = 0.02) were observed for the ankle joint. The hip joint had an increased flexion angle (2%, for p < 0.01) and a reduced range of motion (3%, for p = 0.04) with the increase of workload. Differences in joint kinetics and kinematics indicate that pedaling technique was affected by the combined fatigue and workload effects.  相似文献   

Komagataeibacter intermedius V-05: An Acetic Acid Bacterium Isolated from Vinegar Industry,with High Capacity for Bacterial Cellulose Production in Soybean Molasses Medium     

Rodrigo Jos Gomes  Paula Cristina de Sousa Faria-Tischer  Cesar Augusto Tischer  Leonel Vinicius Constantino  Morsyleide de Freitas Rosa  Roberta Torres Chideroli  Ulisses de Pdua Pereira  Wilma Aparecida Spinosa 《Food Technology and Biotechnology》2021,59(4):432

  相似文献   

Effect of resistance training with different frequencies and subsequent detraining on muscle mass and appendicular lean soft tissue,IGF-1, and testosterone in older women     

Matheus Amarante Do Nascimento  Aline Mendes Gerage  Danilo Rodrigues Pereira Da Silva  Alex Silva Ribeiro  Daniel Gomes Da Silva Machado  Fábio Luiz Cheche Pina 《European Journal of Sport Science》2019,19(2):199-207

Objective: To analyse the effect of resistance training (RT) frequency on muscle mass, appendicular lean soft tissue, insulin-like growth factor 1 (IGF-1), testosterone, and their changes with detraining in older women. Methods: Forty-five physically independent older women (≥ 60?years) were randomly assigned to perform RT either two (G2X, n = 21) or three times/week (G3X, n = 24), during 12?weeks (8 exercises, 1 set of 10–15 repetition maximum). Muscle mass and appendicular lean soft tissue, IGF-1, testosterone, and dietary intake were measured at pre-training, post-training, and after detraining (12?weeks). Results: Muscle mass and appendicular lean soft tissue significantly increased post-training (G2X?=?+5.5% and G3X?=?+5.8%, P?P?P?Conclusion: We conclude that lower RT frequency is as effective as higher frequency to improve muscle mass and appendicular lean soft tissue, and to maintain testosterone and IGF-1. Additionally, detraining may reduce testosterone regardless of RT frequency. These results are specifically for community-dwelling older women and may not be generalized to other populations.  相似文献