A spectral analysis of team dynamics and tactics in Brazilian football     

Felipe Arruda Moura  Luiz Eduardo Barreto Martins  Ricardo O. Anido  Paulo Régis C. Ruffino  Ricardo M. L. Barros  Sergio Augusto Cunha 《Journal of sports sciences》2013,31(14):1568-1577

Abstract

The purposes of this study were to characterise the total space covered and the distances between players within teams over ten Brazilian First Division Championship matches. Filmed recordings, combined with a tracking system, were used to obtain the trajectories of the players (n = 277), before and after half-time. The team surface area (the area of the convex hull formed by the positions of the players) and spread (the Frobenius norm of the distance-between-player matrix) were calculated as functions of time. A Fast Fourier Transform (FFT) was applied to each time series. The median frequency was then calculated. The results of the surface area time series median frequencies for the first half (0.63 ± 0.10 cycles · min^?1) were significantly greater (P < 0.01) than the second-half values (0.47 ± 0.14 cycles · min^?1). Similarly, the spread variable median frequencies for the first half (0.60 ± 0.14 cycles · min^?1) were significantly greater (P < 0.01) than the second-half values (0.46 ± 0.16 cycles · min^?1). The median frequencies allowed the characterisation of the time series oscillations that represent the speed at which players distribute and then compact their team formation during a match. This analysis can provide insights that allow coaches to better control the team organisation on the pitch.  相似文献   

Landing techniques in volleyball     

Roberto Lobietti  Simon Coleman  Eduardo Pizzichillo  Franco Merni 《Journal of sports sciences》2013,31(13):1469-1476

Abstract

Knee injuries such as anterior cruciate ligament lesions and patellar tendonitis are very frequent in volleyball, and are often attributed to micro traumas that occur during the landing phase of airborne actions. The aim of the present study was to compare different jumping activities during official men's and women's volleyball games. Twelve top-level matches from the Italian men's and women's professional leagues were analysed. The jumps performed during the games were classified according to the landing technique used by the player (left or right foot or both feet together), court position, and ball trajectory. Chi-square analyses were performed to detect differences in landing techniques between the sexes, court positions, and trajectories when serving, attacking, blocking, and setting. Significant differences (P < 0.05) were found between the sexes for block, set, and spike but not for the jump serve. The frequency of landings on one foot was related to court position and the trajectory of the sets: when spiking faster sets, the players were more likely to use a one-footed landing. The present results should help coaches and physiotherapists to devise appropriate training and prevention programmes, and reveal the need for further detailed biomechanical investigations of the relationships between landings and knee injuries.  相似文献   

Looking at learning approaches from the angle of student profiles     

Eva Kyndt  Filip Dochy  Katrien Struyven  Eduardo Cascallar 《教育心理学》2012,32(4):493-513

This study starts with investigating the relation of perceived workload, motivation for learning and working memory capacity (WMC) with students’ approaches to learning. Secondly, this study investigates if differences exist between different student profiles concerning their approach to the learning and the influence of workloads thereon. Results show a relation for workload and motivation but not for WMC. By means of a cluster analysis, three student profiles were identified based on WMC and motivation. Students characterised by high WMC and average motivation scored higher on surface approaches and lower on deep approaches than students with high autonomous motivation. These latter students also score higher on deep approaches than students characterised by low WMC. Finally, it was found that all student profiles responded the same to the influence of workload. In contrast with prior research, deep approaches were higher when the workload was higher.  相似文献   

How emotions shape the relationship between a chemistry teacher and her high school students     

Flávia Maria  Teixeira dos Santos  Eduardo Fleury Mortimer 《International Journal of Science Education》2013,35(9):1095-1110

In this article we analyse the interaction between a high school chemistry teacher and her students from two different classes, emphasizing how emotions, affects and feelings contributed to, or obstructed, the dynamic of interactions. The data come from an ethnographic research approach and include videotapes of the lessons, interviews and field notes. Using the distinction introduced by Damasio between primary and secondary emotions, and between emotions and feelings, we describe how the background feelings emerged in different ways in the two classrooms. In class B, the relationships were constructed in a friendly way from the very beginning. The positive emotions that contributed to raising positive background feelings occurred in a high number and frequency. In class A, the picture was completely different, with a higher number and frequency of negative emotions. Thus, emotions and background feelings that were constructed differently in each classroom were at the heart of the different outcomes in terms of attitudes towards chemistry that arose in the two classrooms. In the paper, we also discuss the implication of this kind of analysis for science teaching generally.  相似文献   

Contextualising Learning through the Participatory Construction of an Environmental Education Programme     

Isabel Ruiz‐Mallen  Laura Barraza  Barbara Bodenhorn  Maria de la Paz Ceja‐Adame  Victoria Reyes‐García 《International Journal of Science Education》2013,35(13):1755-1770

Strengthening links between school and community is critical for improving people’s participation in environmental issues. However, Mexican education programmes are generally unrelated to rural students’ life experience and are planned without considering either teachers’ or students’ opinions. This article describes the participatory construction of a preparatory school environmental education (EE) programme in Ixtlan de Juarez, a Mexican indigenous community internationally recognised for sustainable forest management. The qualitative research methods used are based on the action research methodology. Results from interviews conducted with the preparatory school’s headmaster, the coordinator, and nine teachers provided the needed documentation of the school site for contextualising learning activities. Feedback during focus groups with six students, three teachers, five local communal authorities, and two researchers highlighted that all participants perceived the need for creating an educational programme focused on local forest management. The contents and activities of the programme were designed by the focus group’s participants. The programme has been continuously taught by teachers and forest workers since 2005 and was officially integrated with the preparatory school science curriculum in 2006. This participative educational experience has thus transformed the mandatory school curriculum in Ixtlan.  相似文献   

Access to higher education in Chile: A public vs. private analysis     

Oscar Espinoza  Luis Eduardo González 《Prospects》2013,43(2):199-214

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El ordenador como metáfora: Las posibilidades educativas de LOGO     

Eduardo Martí 《Infancia y Aprendizaje》2013,36(26):47-64

Resumen

El autor considera al LOGO como un prototipo de la utilización educativa de los microordenadores que hace hincapié en la autonomía del aprendizaje y a sus aspectos heurísticos.

Desde postulados teóricos de la psicología genética de Piaget, analiza algunas de las particularidades psicológicas y pedagógicas de LOGO: unidades de base significativas para el niño, carácter constructivo e interactivo del aprendizaje, estatuto positivo del error, posibilidad de reflexionar sobre la propia actividad de aprendizaje.

Estos puntos son ilustrados con ejemplos de conductas de niños aprendiendo a programar con LOGO.  相似文献   

When access to drugs meets catch-up: Insights from the use of CL threats to improve access to ARV drugs in Brazil     

Shyama V. Ramani  Eduardo Urias 《Research Policy》2018,47(8):1538-1552

Access to affordable lifesaving medicines is considered a human right. This leads to a question largely understudied in the catch-up literature on accumulation of industrial capabilities. Can the need to improve access to an essential commodity impact the sectoral catch-up trajectory of the corresponding industry? In 1996, Brazil initiated a policy of universal and free access to highly-active ARV therapy, which put an enormous pressure on the Brazilian Ministry of Health (MoH). In order to ensure an adequate supply of ARVs in the public healthcare system with a limited budget, MoH started negotiating price reductions for high-cost patented drugs, often deploying the threat of using compulsory licensing. Through a scoping review of the literature and construction of the Brazilian case study, the paper explores how the need to access is impacted by prior catch-up in the pharmaceutical sector and triggers in turn future sectoral catch-up. It shows that price negotiations may or may not impact both catch-up and access positively. Catch-up can provide bargaining strength in price negotiations and have a positive inter-temporal impact on both future catch-up and access. However, results suggest that only successful catch-up can lead to long term access, as the capabilities accumulated in aborted catch-up are not sufficient for large scale production of low cost essential medicines. Thus, industrial policy and health policy can impact one another and twining between catch-up and access can be helpful.  相似文献   

Parasympathetic activity delayed after self-paced exercise     

Lucas Rosiello Trojbicz  Mayara Vieira Damasceno  Leonardo Alves Pasqua  Arthur Fernandes Gáspari  Adriano Eduardo Lima-Silva 《European Journal of Sport Science》2018,18(6):842-850

The main purpose of this study was to compare the effect of the constant load and self-paced exercise with similar total work on autonomic control after endurance exercise. Ten physically active men were submitted to (i) a maximal incremental exercise test, (ii) a 4-km cycling time trial (4-km TT), and (iii) a constant workload test with identical total external work performed at 4-km TT. Gas exchange was measured throughout the tests, while blood lactate, heart rate, and heart rate variability (HRV) were measured during the passive recovery. Power output measured at the last lap (i.e. 3600–4000?m) of 4-km TT (316?±?89?W) was statistically higher than power output measured at the end of the constant workload exercise (211?±?42?W). The 4-km TT produced higher values of blood lactate concentration (8.8?±?2.1?mmol?L^?1) than the constant workload test (7.8?±?2.1?mmol?L^?1). The heart rate recovery measured at 60?s (constant workload: 37?±?7?bpm; 4-km TT: 30?±?6) and 120?s (constant workload: 57?±?9?bpm; 4-km TT: 51?±?9?bpm) were higher in the constant workload than in the self-paced exercise. The HRV (i.e. RMSSD30s) was statistically higher in the constant load exercise measured at 120, 420, 450, 480, 540, and 570?s than the self-paced exercise. These findings suggest that the autonomic control responses were dependent of the endurance exercise modalities, with parasympathetic activity being delayed after self-paced exercise, as evidenced by post-exercise heart rate indices.  相似文献   

Fast distributed algebraic connectivity estimation in large scale networks     

Eduardo Montijano  Juan I. Montijano  Carlos Sagues 《Journal of The Franklin Institute》2017,354(13):5421-5442

This paper presents a distributed method to estimate the algebraic connectivity of fixed undirected communication graphs. The proposed algorithm uses bisection to estimate the second smallest eigenvalue of the Laplacian matrix associated to the graph. In order to decide the sub-interval in which the eigenvalue is contained, a distributed averaging algorithm based on Chebyshev polynomials is considered together with a max consensus algorithm. The information exchanged by neighbors in the graph each communication round is constant and independent of the size of the network, making it scalable to large networks. Besides, exploiting the convergence properties of Chebyshev polynomials we provide a direct estimation of the algebraic connectivity so that, instead of the midpoint of the bisection interval, the new approximation can be used. Finally, our algorithm also provides upper and lower bounds on the algebraic connectivity and an estimation of the Fiedler eigenvector associated to it. Simulations in large networks demonstrate the scalability and accuracy of the algorithm.  相似文献