Effects of Voluntary and Automatic Control of Center of Pressure Sway During Quiet Standing

The authors investigated the effects of voluntary and automatic control on the spatial variables (envelope area, maximal amplitude, and root mean square [RMS]) of center of pressure (COP) displacement during quiet standing and identified differences in their postural control strategies (mean velocity [MV], mean power frequency [MPF], and power density). COP data were recorded under relaxed (experimental control), still (voluntary control), and dual (automatic control) conditions. RMS was significantly lower in the still and dual conditions than in the relaxed condition. MV, MPF, and power density were significantly higher in the still condition than in the dual condition. These results indicate that both voluntary and automatic control decrease the spatial variables of COP displacement; however, their postural control strategies are different.     

Analysis of the Movement-Inducing Effects of Music through the Fractality of Head Sway during Standstill

Abstract

The links between music and human movement have been shown to provide insight into crucial aspects of human’s perception, cognition, and sensorimotor systems. In this study, we examined the influence of music on movement during standstill, aiming at further characterizing the correspondences between movement, music, and perception, by analyzing head sway fractality. Eighty seven participants were asked to stand as still as possible for 500?seconds while being presented with alternating silence and audio stimuli. The audio stimuli were all rhythmic in nature, ranging from a metronome track to complex electronic dance music. The head position of each participant was captured with an optical motion capture system. Long-range correlations of head movement were estimated by detrended fluctuation analysis (DFA). Results agree with previous work on the movement-inducing effect of music, showing significantly greater head sway and lower head sway fractality during the music stimuli. In addition, patterns across stimuli suggest a two-way adaptation process to the effects of music, with musical stimuli influencing head sway while at the same time fractality modulated movement responses. Results indicate that fluctuations in head movement in both conditions exhibit long-range correlations, suggesting that the effects of music on head movement depended not only on the value of the most recent measured intervals, but also on the values of those intervals at distant times.     

Postural Sway and the Amplitude of Horizontal Eye Movements

In 2 experiments, we evaluated relations between postural activity and the amplitude of visually guided eye movements. Participants shifted their gaze to follow horizontal oscillation of a visible target. The target moved with amplitude 9° or 24°. In different experiments, the frequency of target oscillation was 0.5 Hz or 1.1 Hz. In both experiments, the variability of head and torso motion was reduced (in the anterior-posterior axis) when participants viewed moving targets, relative to sway during viewing of stationary targets. Sway variability was not influenced by the amplitude of target motion. The results are compatible with the hypothesis that postural activity was modulated relative to the demands of suprapostural visual tasks.     

Dual-Task Training Reduces Impact of Cognitive Task on Postural Sway

Given the flexible organization of locomotion evidenced in the many ways the limbs can be coordinated, the authors explored the potentially correspondingly flexible organization of nonvisual (kinesthetic) distance perception. As kinesthetic distance perception is known to be affected by how the limbs are coordinated, the authors probed the potential perceptual contribution of the arms during locomotion by manipulating arm–leg coordination patterns in blind-walked distance-matching tasks. Whereas manipulation of arm–leg coordination for walking with free-swinging arms had no observable perceptual consequences, comparable manipulation for walking with hiking poles did affect distance matching. These results suggest that under conditions in which the arms act to propel the body (e.g., crawling or stair-climbing) a person's nonvisual sense of movement is conveyed in the coordinated actions of all four limbs.     

Balance Performance During Perturbed Standing Is Not Associated With Muscle Strength and Power in Young Adults

The authors investigate the ways in which varied postural responses to translating platform perturbations are associated with the variables of strength and power. Twenty-four physically active and 27 sedentary young adults were exposed to a set of postural perturbations at varied velocities (10 and 20 cm/s) and the respective accelerations (6.4 and 6.9 m/s²), constant distance (6 cm), and 4 directions of platform motion (forward, backward, left-lateral, and right-lateral). They also performed maximum voluntary isometric contraction (MVC) and chair rising/chair jumping tests. The analysis of variance revealed significant interaction effect for peak center of pressure displacement, direction by velocity: F_3,129 = 24.43, p = .002; and direction by acceleration: F_3,129 = 34.18, p = .001. There were no significant correlations between peak center of pressure displacements and peak force and peak rate of force development measured during MVC in either standing (r = .27–57) or sitting positions (r = .12–51) and peak power during chair jumping (r = .47–.59) in all participants. As such, only a small proportion of variance was explained (9–39%, 3–23%, and 23–41%, respectively). In conclusion, interaction effects indicate that the composition of stimuli strongly influences compensatory responses and this effect is more pronounced in sedentary than in physically active young adults. Nevertheless, the dynamic balance is not associated with muscle strength and power in either group.     

The Role of Visual Feedback about Motion of the Ground on Postural Sway

Abstract

We asked whether body sway would be influenced by visual information about motion of the ground surface. On a ship at sea, standing participants performed a demanding visual search task or a simple visual inspection task. Display content was stationary relative to the ship or relative to the Earth. Participants faced the ship’s bow or its port side. Performance on the visual search task was representative of terrestrial studies. Body sway was greater during viewing of the Earth Stationary displays than during viewing of the Ship Stationary displays. We discuss possible implications of these results for theoretical and applied issues.     

论医者的权力

权力是人们建构社会关系以及支配社会行为的重要中介,在医疗领域中也是如此。在医患关系中,医者占据着主导性的权力地位。医者权力可以经由专业知识、资源占有和国家赋权等途径产生,并且有着复杂的表现形式。医者权力是医疗实践的产物,具有合理性,同时也存在被滥用的风险。为了医者权力的合理实现,人们试图以“德性制约权力”或以“权利制约权力”,这些路径有着重要的价值,但也有其局限性。规制医者权力,最根本的是以实现人性化的医学为目的,不断反思和重构医学的制度体系。权力分析应当成为建设和谐医患关系的重要理论基础。

     

Standing on the Shoulders of Giants

Little is known about classical Christian schools and their leaders in the United States. This study describes the headmasters of such schools and their sense of job satisfaction, job efficacy, and career aspirations. Numerous significant relationships among the variables were found, including between job satisfaction and a headmaster's relationships with the board, faculty, and parents. A regression analysis indicated that 45% of the variance in their sense of job satisfaction was predicted by transactional leadership qualities, relationships with the governing bodies, classical pedagogy, and career aspirations.     

Standing in for King Solomon: The Potential Contribution of Human Resource Management to the Implementation of the Stakeholder Approach

Abstract

Most contemporary theorists are in agreement that human resource management (HRM) has a special role to play in affecting the direction of organizational philosophy at the enterprise strategy level. Accordingly, the suggestion is made in this paper that HRM should spearhead the introduction of stakeholder management strategy concepts into organizational thinking and practices. Stakeholder management strategy can be defined as matching the organization's ‘values’ to the ‘values’ of its stakeholders and maximizing, over the long term, the net (social and economic) value added to society. The paper argues that HRM is potentially the best equipped, and strategically the best positioned, to anticipate, monitor and co-ordinate the effects of corporate policy on stakeholders' interests. It may thus serve as a major vehicle for mobilizing and maintaining the support of groups and individuals in the organization's internal and external environment who are parties to the social contract that legitimizes its continued existence and development.     

Standing distance in climbability of stairs.

The purpose of this experiment was to make a preliminary examination of the distance one needs to stand from a stair to successfully climb up without using arms for support. Using an adjustable stair structure to create different heights of risers, a group of 10 tall and of 10 short participants made perceptual judgments and physical attempts at heights that represented 83% and 93% of each group's mean leg length. Choice of maximum and minimum distance from the stair was measured for each participant. Analysis showed that perceptual judgments and physical capabilities were highly correlated (tall: Pearson r = .92); short: Pearson r = .93). Moreover, the ability to climb the two heights depended on the standing distance from the stair. The findings suggest that standing distance may be a consideration in stair climbing and that stair height alone may not be sufficient to specify climbability.     

"人类中心主义"辨正

20世纪中叶以来 ,人们开始强烈地意识到人类生存的自然环境正在急剧恶化 ,严峻的现实把一个古老的问题—人与自然的关系问题 ,凸现在世人面前 ,并由此引发了人们对“人类中心主义”的思考。在我国学界逐渐形成了非人类中心主义派别和人类中心主义派别。我以为 ,两大派别之所以会产生分歧 ,主要原因在于其对“人类中心主义”的内涵及其理解未达成共识 ,故而在使用上呈现出模糊性、混乱性。为了能够克服人类中心主义讨论中的某些局限性并将对这一问题的研究推向深入 ,本文拟就“人类中心主义”的真实内涵和本质略陈孔见。从历史上看 ,人类中心…     

诚实信用原则与先合同义务

诚实信用原则的勃兴成为现代合同法理论与实践发展的一个显著特征 ,以诚实信用为基础产生的先合同义务也成为合同义务群的一个重要组成部分。先合同义务及缔约过失责任的产生和发展实现了合同利益的扩大化保护 ,体现了合同法的价值关怀。     

Differences in Rapid Initiation and Termination of Voluntary Postural Sway Associated with Ageing and Falls-Risk

The authors examined differences between young adults (n = 25) and healthy older adults (n = 48) in reaction time and the relations between center of pressure (COP) and center of mass (COM) motions during rapid initiation and termination of voluntary postural sway. Older adults were divided into low and high falls-risk groups based on Physiological Profile Assessment scores of sensorimotor function. Low falls-risk older adults had slower reaction times during anteroposterior sway initiation and decreased COP–COM separation during anteroposterior and medialateral sway initiation and anteroposterior continuous voluntary sway compared with young adults. High falls-risk older adults had slower initiation and termination reaction times in all response directions and decreased COP–COM separation during sway initiation and continuous voluntary sway in the anteroposterior and medialateral directions compared with young adults. Compared with low falls-risk older adults, high falls-risk older adults had slower initiation and termination reaction times in all response directions and decreased COP–COM separation during medialateral continuous voluntary sway. Reaction time and COP–COM measures significantly predicted group status in discriminant models with sensitivities and specificities of 72–100%. Overall, these findings highlight important associations of age-related declines in sensorimotor function related to an increased risk of falling with slower postural reaction time and reduced postural stability.     

人权的普世价值与超级大国的战略利益

从 1 977年开始 ,美国国务院一年一度发布《各国人权报告》 ,已经进行了四分之一个世纪。虽然受到《2 0 0 3年度各国人权报告》(以下简称《报告》)批评的印度政府将此称作只是美国国务院的“例行公事” ,但是 ,谁也无法否定 ,这种持之以恒的“例行公事”已经产生了深远和重大的     

Standing up for an affective account of emotion

This paper constitutes a defence of an affective account of emotion. I begin by outlining the case for thinking that emotions are just feelings. I also suggest that emotional feelings are not reducible to other kinds of feelings, but rather form a distinct class of feeling state. I then consider a number of common objections that have been raised against affective accounts of emotion, including: (1) the objection that emotion cannot always consist only of feeling because some emotions—for example, indignation and regret—necessarily have a cognitive component (say, the perception of a lost opportunity in the case of regret); (2) the objection that emotion cannot consist only of feeling because in order to explain how emotions have intentional objects we will have to recognise that emotion consists of cognition; and (3) the objection that emotion cannot consist only of feeling because emotion, but not feeling, can be variously assessed or evaluated. However, I demonstrate how an affective account of emotion might be successfully defended against all of the objections that are cited.     

Assessment of postural control in patients with Parkinson’s disease: Sway ratio analysis

Analysis of the postural stability impairments in neurodegenerative diseases is a very demanding task. Age-related declines in posturographic indices are usually superimposed on effects associated with the pathology and its treatment. We present the results of a novel postural sway ratio (SR) analysis in patients with Parkinson’s disease (PD) and age-matched healthy subjects. The sway ratios have been assessed based upon center of foot-pressure (CP) signals recorded in 55 parkinsonians (Hoehn and Yahr: 1-3) and 55 age-matched healthy volunteers while standing quiet with eyes open (EO) and then with eyes closed (EC). Complementing classical sway measure abnormalities, the SR exhibited a high discriminative power for all controlled factors: pathology, vision, and direction of sway. Both the anteroposterior (AP) and mediolateral (ML) sway ratios were significantly increased in PD patients when compared to the control group. An additional SR increase was observed in the response to eyes closure. The sway ratio changes documented here can be attributed to a progressive decline of a postural stability control due to pathology. In fact, a significant correlation between the mediolateral SR under EO conditions and Motor Exam (section III) score of the UPDRS was found. The mediolateral sway ratios computed for EO and EC conditions significantly correlated with the CP path length (r = .87) and the mean anteroposterior CP position within the base of support (r = .38). Both indices reflect postural stability decline and fall tendency # in parkinsonians. The tremor-type PD patients (N = 34) showed more pronounced relationships between the mediolateral SR and selected items from the UPDRS scale, including: falls (Kendall Tau = .47, p < .05), rigidity (.45, p < .05), postural stability (retropulsion) (.52), and the Motor Exam score (.73). The anteroposterior SR correlated only with tremor (Kendal Tau = .77, p < .05). It seems that in force plate posturography the SR can be recommended as a single reliable measure that allows for a better quantitative assessment of postural stability impairments.