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41.
Ricardo Duarte Duarte Araújo Keith Davids Bruno Travassos Vítor Gazimba Jaime Sampaio 《Journal of sports sciences》2013,31(9):871-877
Abstract This study investigated the influence of interpersonal coordination tendencies on performance outcomes of 1-vs-1 sub-phases in youth soccer. Eight male developing soccer players (age: 11.8 ± 0.4 years; training experience: 3.6 ± 1.1 years) performed an in situ simulation of a 1-vs-1 sub-phase of soccer. Data from 82 trials were obtained with motion-analysis techniques, and relative phase used to measure the space-time coordination tendencies of attacker-defender dyads. Approximate entropy (ApEn) was then used to quantify the unpredictability of interpersonal interactions over trials. Results revealed how different modes of interpersonal coordination emerging from attacker-defender dyads influenced the 1-vs-1 performance outcomes. High levels of space-time synchronisation (47%) and unpredictability in interpersonal coordination processes (ApEn: 0.91 ± 0.34) were identified as key features of an attacking player's success. A lead-lag relation attributed to a defending player (34% around ?30° values) and a more predictable coordination mode (ApEn: 0.65 ± 0.27, P < 0.001), demonstrated the coordination tendencies underlying the success of defending players in 1-vs-1 sub-phases. These findings revealed how the mutual influence of each player on the behaviour of dyadic systems shaped emergent performance outcomes. More specifically, the findings showed that attacking players should be constrained to exploit the space-time synchrony with defenders in an unpredictable and creative way, while defenders should be encouraged to adopt postures and behaviours that actively constrain the attacker's actions. 相似文献
42.
João Carvalho Duarte Araújo Bruno Travassos Pedro Esteves Luís Pessanha Fernando Pereira 《Journal of sports sciences》2013,31(14):1596-1605
Abstract This study analysed how the relative positioning of players on court influenced patterns of interpersonal coordination in baseline rallies in tennis. We developed a model (PA index) that assigns a weight to the position of each player on court and determines a positional advantage, based on the relative proportionality between the lateral and longitudinal displacement values during rallies. To test the model, data from 27 randomly-selected baseline rallies from three ATP World Tour matches (professional tennis players' tournaments organized by Association of Tennis Professionals) on clay were analysed. Results revealed that the PA index of players on court described their interpersonal coordination dynamics during baseline rallies. It also identified the emergence of rally breaks in the interpersonal coordination patterns of competing dyads that led to a point being scored. Data suggest that positional advantage data may assist coaches in the design of training tasks to enhance players' court coverage and performance during competitive interactions, acting as a valuable tool for performance analysis in tennis. 相似文献
43.
This paper presents a complementary analytical approach to characterize vegetable tanning materials in historic leathers. It is described the application of two molecular spectroscopic techniques, ATR-FTIR and UV-Vis, and three specific chemical tests to analyse tannins present in leathers. Acid butanol, nitrous acid and rhodanine colorimetric tests, evaluated both visually and spectrophotometrically, were used to identify condensed tannins, ellagitannins and gallotannins, respectively. Ten samples of commercial, or laboratory prepared, vegetable tannins and seven new vegetable tanned leathers were also analysed and obtained results were used for comparison. The complete analytical procedure was performed, in a semi-micro-destructive scale, using fibres collected from leather. Analysis of ATR-FTIR and UV spectra of commercial and laboratory prepared vegetable tannins allowed the establishment of the characteristic bands of condensed and hydrolysable tannins and, more specifically, gallotannins. These data were used to confirm the type of vegetable tanning agents used in new leather extracts. The same approach was used in cultural heritage leathers, supported by the colorimetric tests, since protein degradation products were co-extracted in aged leathers and interfered in IR spectra. 相似文献
44.
Previous research on coordination dynamics of 1 vs. 1 sub-phases in team sports has reported stable emergent patterns of coordination in the displacement trajectories of attackers and defenders. The aim of this study was to use attacker-defender interactions in competitive team match-play to investigate how the locations of the goal and ball constrain the pattern-forming dynamics of attacker-defender dyadic systems. Ten high-level futsal matches were filmed and 13 goal sequences selected for analysis. Displacements of the players and the ball were filmed and digitized from 52 attacker-defender dyadic system interactions. Results showed that, although attackers and defenders exhibited similar angular orientations to the goal, the latter always remained closer to the goal than attackers. Observations revealed that in-phase patterns of coordination emerged from changes to both the distances and angles of attackers and defenders to the goal. Attackers always remained closer to the ball than defenders, while the latter exhibited a lower angle to the ball than attackers. A pattern of in-phase coordination modes emerged between the attackers and defenders' distances and angles to the ball. This study helps us to understand interpersonal interactions in team sports by explaining how attackers and defenders use information about their relative positioning to the goal and the ball to perform successfully. 相似文献
45.
Interpersonal coordination tendencies shape 1-vs-1 sub-phase performance outcomes in youth soccer 总被引：2，自引：2，他引：0
Duarte R Araújo D Davids K Travassos B Gazimba V Sampaio J 《Journal of sports sciences》2012,30(9):871-877
This study investigated the influence of interpersonal coordination tendencies on performance outcomes of 1-vs-1 sub-phases in youth soccer. Eight male developing soccer players (age: 11.8 ± 0.4 years; training experience: 3.6 ± 1.1 years) performed an in situ simulation of a 1-vs-1 sub-phase of soccer. Data from 82 trials were obtained with motion-analysis techniques, and relative phase used to measure the space-time coordination tendencies of attacker-defender dyads. Approximate entropy (ApEn) was then used to quantify the unpredictability of interpersonal interactions over trials. Results revealed how different modes of interpersonal coordination emerging from attacker-defender dyads influenced the 1-vs-1 performance outcomes. High levels of space-time synchronisation (47%) and unpredictability in interpersonal coordination processes (ApEn: 0.91 ± 0.34) were identified as key features of an attacking player's success. A lead-lag relation attributed to a defending player (34% around -30° values) and a more predictable coordination mode (ApEn: 0.65 ± 0.27, P < 0.001), demonstrated the coordination tendencies underlying the success of defending players in 1-vs-1 sub-phases. These findings revealed how the mutual influence of each player on the behaviour of dyadic systems shaped emergent performance outcomes. More specifically, the findings showed that attacking players should be constrained to exploit the space-time synchrony with defenders in an unpredictable and creative way, while defenders should be encouraged to adopt postures and behaviours that actively constrain the attacker's actions. 相似文献
46.
Ana Paulo Frank T.J.M. Zaal Ludovic Seifert Sofia Fonseca Duarte Araújo 《Journal of sports sciences》2018,36(22):2621-2630
In a group-serve-reception task, how does serve-reception become effective? We addressed “who” receives/passes the ball, what task-related variables predict action mode selection and whether the action mode selected was associated with reception efficacy. In 182 serve-receptions we tracked the ball and the receivers’ heads with two video-cameras to generate 3D world-coordinates reconstructions. We defined receivers’ reception-areas based on Voronoi diagrams (VD). Our analyses of the data showed that this approach was accurate in describing “who” receives the serve in 95.05% of the times. To predict action mode selection, we used variables related to: serve kinematics, receiver’s movement and on-court positioning, the relation between receiver and his closest partner, and interactions between receiver-ball and receiver-target. Serve’s higher initial velocities together with higher maximum height, as well as smaller longitudinal distances between receiver and target increased the chances for the use of the overhand pass. Conversely, decreasing alignment of the receiver with the ball and the target increased the chances of using the underhand-lateral pass. Finally, the use of the underhand-lateral pass was associated with lower quality receptions. Behavioural variability’s relevance for serve-reception training is discussed. 相似文献
47.
Sandra T. Valadas Leandro S. Almeida Alexandra M. Araújo 《Scandinavian Journal of Educational Research》2017,61(6):721-734
Students’ personal predictors of academic success are particularly relevant for first-year college students, given the specific challenges that these students face when entering higher education (HE). Academic success in HE has been related to multiple factors, including the students’ approaches to learning (SAL), satisfaction (linked to commitment and persistence), study time (effort), and prior academic achievement. This study analyzes the combined effect of these predictors on perceived academic success. Data from 247 students was collected using the Approaches and Study Skills Inventory for Students and other specific measures to assess presage and process variables of academic success. Although academic success is multidimensional and difficult to explain, factors such as prior academic achievement, satisfaction with the course, SAL, and study time contribute to explain perceived academic success in first-year college students. 相似文献
48.
Weslei Gomes de Sousa Elis Regina Pereira de Melo Paulo Henrique De Souza Bermejo Rafael Araújo Sousa Farias Adalmir Oliveira Gomes 《Government Information Quarterly》2019,36(4):101392
To obtain benefits in the provision of public services, managers of public organizations have considerably increased the adoption of artificial intelligence (AI) systems. However, research on AI is still scarce, and the advance of this technology in the public sector, as well as the applications and results of this strategy, need to be systematized. With this goal in mind, this paper examines research related to AI as applied to the public sector. A review of the literature covering articles available in five research databases was completed using the PRISMA protocol for literature reviews. The search process yielded 59 articles within the scope of the study out of a total of 1682 studies. Results show a growing trend of interest in AI in the public sector, with India and the US as the most active countries. General public service, economic affairs, and environmental protection are the functions of government with the most studies related to AI. The Artificial Neural Networks (ANN) technique is the most recurrent in the investigated studies and was pointed out as a technique that provides positive results in several areas of its application. A research framework for AI solutions for the public sector is presented, where it is demonstrated that policies and ethical implications of the use of AI permeate all layers of application of this technology and the solutions can generate value for functions of government. However, for this, a prior debate with society about the use of AI in the public sector is recommended. 相似文献
49.
Diego Munguía-Izquierdo Luis Suárez-Arrones Valter Di Salvo Victor Paredes-Hernández Ignacio Ara Alberto Mendez-Villanueva 《Journal of sports sciences》2019,37(11):1197-1204
This study determined the most effective field method for quantifying fat-free mass (FFM) in elite youth male soccer players compared to dual X-ray absorptiometry (DXA) values and to develop prediction equations for FFM based on anthropometric variables. Forty-one male elite-standard youth soccer players, ages 16.2–18.0 years, undertook FFM assessments including bioelectrical impedance analysis, and different skinfold-based prediction equations. DXA provided a criterion measure of FFM. Correlation coefficients, bias, limits of agreement, and differences were used as validity measures, and regression analyses to develop soccer-specific prediction equations. Slaughter et al (1988), Durnin and Wormersley (1974), and Sarria et al (1998) equations showed the lowest biases, and no significant, standardized, and substantial differences against DXA. The new youth soccer-specific anthropometric equation explained 91% of the DXA-derived FFM variance using three circumferences, eight skinfolds, and one bone breadth. All field methods compared in this study may not be adequate for estimating FFM in elite youth male soccer players, except the equations of Slaughter et al (1988), Durnin and Wormersley (1974), and Sarria et al (1998). We recommend the use of the new soccer-specific equation proposed in this study as a valid alternative to DXA to quantify FFM among elite youth male players. 相似文献
50.
Rui Manuel Flores Araújo Peter Andrew Hastie Cristiana Helena de Assunção Bessa Pereira Isabel Maria Ribeiro Mesquita 《Physical Education & Sport Pedagogy》2017,22(5):518-535
Background: One of the essential elements within Sport Education is the inclusion of student roles and responsibilities. While previous research has examined students’ performance in officiating tasks, the examination of student-coaches’ pedagogical content knowledge (PCK) within peer-assisted tasks of Sport Education has been scarce. Indeed, the only study to date which has examined student-coach effectiveness was conducted by Wallhead and O’Sullivan [2007. “A Didactic Analysis of Content Development During the Peer Teaching Tasks of a Sport Education Season.”Physical Education and Sport Pedagogy 12 (3): 225–243]. In that study, student-coaches struggled to manifest PCK by providing appropriate demonstrations, to diagnose errors, or to modify tasks for higher order content development. The study of PCK may be a useful heuristic to examine instructional effectiveness in physical education.
Purpose: The purpose of this study was to examine the evolution of the PCK of a cohort of student-coaches across three hybrid Sport Education-Step Game Approach seasons, and to examine the impact of protocols put in place to specifically enhance coaches’ PCK.
Participants and setting: Twenty-one students and one teacher from a school class in the north of Portugal participated in the present study.
Method: Data from multiple sources were collected: (a) videotape observations of all lessons, (b) field notes, and (c) pre-lesson interviews with the student-coaches. These were then subjected to deductive examination through a process of thematic analysis.
Findings and conclusions: Following a baseline season that identified four key limitations within the student-coaches’ instruction (task presentation, error diagnosis, feedback, and task modification), these students participated in specific coach preparation that involved modelling teacher’s instruction, pre-lesson meetings, and coaches’ corners. While showing marked improvement in their content knowledge across the second season, a second protocol was instigated during the third that involved the student-coaches to participate in stimulated reflections of their instruction and the incorporation of planning sheets to enhance their instruction. It was found that both interventions were efficacious in developing student-coaches’ PCK, which allowed a more complete transfer of the instructional responsibility from the teacher to the students. These results give insight into the importance of including coach education protocols within the design of seasons of Sport Education with respect to student-coaches’ instructional preparation. 相似文献