A dynamical system perspective to understanding badminton singles game play

By altering the task constraints of cooperative and competitive game contexts in badminton, insights can be obtained from a dynamical systems perspective to investigate the underlying processes that results in either a gradual shift or transition of playing patterns. Positional data of three pairs of skilled female badminton players (average age 20.5 ± 1.38 years) were captured and analyzed. Local correlation coefficient, which provides information on the relationship of players’ displacement data, between each pair of players was computed for angle and distance from base position. Speed scalar product was in turn established from speed vectors of the players. The results revealed two patterns of playing behaviors (i.e., in-phase and anti-phase patterns) for movement displacement. Anti-phase relation was the dominant coupling pattern for speed scalar relationships among the pairs of players. Speed scalar product, as a collective variable, was different between cooperative and competitive plays with a greater variability in amplitude seen in competitive plays leading to a winning point. The findings from this study provide evidence for increasing stroke variability to perturb existing stable patterns of play and highlights the potential for speed scalar product to be a collective variable to distinguish different patterns of play (e.g., cooperative and competitive).     

中医药发展的挤出效应及制度耦合

制度与制度之间常常存在挤出效应,在医疗卫生服务制度体系内,价格管制、支付制度和医疗卫生服务评价制度等,造成了对中医药政策和中医药应用的挤出.而中医药在我国医改战略转型、医学模式转变和促进制度创新方面具有十分积极的意义.制度耦合是解决制度冲突、制度挤出的基本思想,把中西医统一到卫生事业发展的目标上来,把发挥中医药优势和特色作为中医药政策的核心,构建中西医并重的机制、优化医疗卫生服务制度结构和完善中医药评价体系,是缓解挤出效应,促进中医药发展的制度选择.     

Pattern Stability and Error Correction During In-Phase and Antiphase Four-Ball Juggling

The authors studied pattern stability and error correction during in-phase and antiphase 4-ball fountain juggling. To obtain ball trajectories, they made and digitized high-speed film recordings of 4 highly skilled participants juggling at 3 different heights (and thus different frequencies). From those ball trajectories, the authors determined and analyzed critical events (i.e., toss, zenith, catch, and toss onset) in terms of variability of point estimates of relative phase and temporal correlations. Contrary to common findings on basic instances of rhythmic interlimb coordination, in-phase and antiphase patterns were equally variable (i.e., stable). Consistent with previous findings, however, pattern stability decreased with increasing frequency. In contrast to previous results for 3-ball cascade juggling, negative lag-one correlations for catch-catch intervals were absent, but the authors obtained evidence for error corrections between catches and toss onsets. That finding may have reflected participants' high skill level, which yielded smaller errors that allowed for corrections later in the hand cycle.     

Piezoelectric and electromechanical coupling constants for GaxIn1-xSb semiconducting alloys

The compositional dependence of piezoelectric stress and strain constants and electromechanical coupling coefficient of Ga_xIn_1-xSb have been investigated. The calculations were performed using a pseudopotential approach combined with the Adachi model where different concepts of ionicity are considered. Our results are compared with the available data and found to be in good accord with each other. Our findings show that as the Ga content varies, the piezoelectric and related constants and transport properties of the alloy system of interest are significantly affected.     

Exploring the Within-Person Coupling of Reading Vision and Cognition in the Elderly

ABSTRACT

This study examined the within-person relationship between reading vision and cognitive functioning. Analysis was conducted on 36 community-dwelling elderly (age range?=?60–87) who completed a reading vision task and three cognitive tests (i.e., Rey Auditory Verbal Learning Task (AVLT), Letter Series, and Number Comparison) twice a day over 60 consecutive days. Significant within-person variability was found for the reading vision measure. Additionally, a main effect was found for reading vision and performance on the AVLT and Number Comparison task; such that on occasions when reading vision was poor, cognitive performance suffered.     

The coupling of head,reach and grasp movement in nine months old infant prehension

In 9-month-old-infants adjustments in the reaching pattern to sudden changes in object location were examined. An attractive ball was presented to the infants at their midline and on some trials (perturbation trials) the ball suddenly changed position 15 cm to the right or left during the reach. For the perturbed trials the movement times approximately doubled compared to the control trials and significantly fewer balls were grasped. The results indicate that infants need to finish the first movement before being able to redirect the reach to a new destination. The correlation between the latency of the head and hand adjustment to the perturbation were 0.85 and 0.78 for movements to the left and to the right, respectively, indicating a tight coupling. The time between the start of the perturbation and peak velocity (TPPV) was significantly shorter for the head movement than for the hand movement, indicating that the head is leading the hand.     

Coupling of postural and manual tasks in expert performers

The purpose of this study was to investigate the integration of bimanual rhythmic movements and posture in expert marching percussionists. Participants (N = 11) performed three rhythmic manual tasks [1:1, 2:3, and 2:3-F (2:3 rhythm played faster at a self-selected tempo)] in one of three postures: sitting, standing on one foot, and standing on two feet. Discrete relative phase, postural time-to-contact, and coherence analysis were used to analyze the performance of the manual task, postural control, and the integration between postural and manual performance. Across all three rhythms, discrete relative phase mean and variability results showed no effects of posture on rhythmic performance. The complexity of the manual task (1:1 vs. 2:3) had no effect on postural time-to-contact. However, increasing the tempo of the manual task (2:3 vs. 2:3-F) did result in a decreased postural time-to-contact in the two-footed posture. Coherence analysis revealed that the coupling between the postural and manual task significantly decreased as a function of postural difficulty (going from a two-footed to a one-footed posture) and rhythmic complexity (1:1 vs. 2:3). Taken together, these results demonstrate that expert marching percussionists systematically decouple postural and manual fluctuations in order to preserve the performance of the rhythmic movement task.     

Representative design: Does the addition of a defender change the execution of a basketball shot?

ObjectiveThe aim of this study was to examine the influence of a defender on the performance of a motor skill from an invasion sport.DesignHighly skilled basketball players performed different variations of basketball shots using a randomised test schedule.MethodParticipants completed a total of 30 test trials comprising 6 trials of 5 different shot types in both defended and undefended conditions.ResultsThe presence of a defender led to significant changes in several behavioral measures including faster shot execution times, longer jump times, and an increase in the amount of time that the ball spent in the air as it travelled to the basket after being released from the shooter's hand. These behavioral changes were accompanied by an overall decline in shooting accuracy of over 20%. Defended shots also tended to elicit greater amounts of movement variability which, when interpreted in conjunction with the other findings, suggests that participants were attempting to adapt their movements to accommodate for the changing demands of the performance environment. Comparisons across different shot types revealed that the influence of the defender was generally context and task dependent.ConclusionsThe results have important implications for representative task design, and highlight how the manipulation of key information sources can have a marked effect upon behavioral responses.     

The amount of recent action-outcome coupling modulates the mechanisms of the intentional binding effect: A behavioral and ERP study

Our everyday interactions depend on the ability to maintain a feeling of control over our bodily actions, that is, the sense of agency. The intentional binding effect – a perceived temporal shortening between voluntary actions and sensory outcomes – has been shown to implicitly measure agency. We investigated the effect’s underlying mechanisms: prediction and retrospective inference. First, long-term and recent action-outcome coupling were compared. Second, brain activity was recorded to uncover the neural correlates of the two mechanisms. Our results show that the recent accumulation of action-outcome coupling, but not that of a long-term accumulation, is correlated with the binding effect of actions and accounts for both mechanisms. Temporal action binding was reflected in both the readiness potential and the auditory evoked potential. The results shed new light on our understanding of the influence that immediate context of an action has on its temporal binding and the neural substrate of human agency.