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.     

Undisturbed Upright Stance Control in the Elderly: Part 1. Age-Related Changes in Undisturbed Upright Stance Control

The authors investigated age-related changes in postural control in 33 healthy young adults (18-31 years), 29 seniors (62-75 years), and 22 elderly people (75-96 years). A force platform recorded the results. The horizontal motions of the center of gravity (CG_h) and their difference in the plane of support CP - CG_v were deduced from the complex center of pressure (CP) trajectories. With fractional Brownian modeling, one can establish that the aging process seems to induce a transition phase in which seniors take more time to initiate the corrective process in the mediolateral (ML) axis than do younger people. The elderly develop a new strategy characterized by the mobilization of higher neuromuscular energy to maintain equilibrium. In the ML axis, the larger displacements could be caused mainly by a hip strategy that could facilitate step initiation. In the anteroposterior (AP) axis, seniors and elderly individuals maintain a relative ability to stabilize their CG into the base of support compared with younger people.     

Effect of Heel Heights on Female Postural Control During Standing on a Dynamic Support Surface With Sinusoidal Oscillations

The authors aimed to investigate female balance or stability control with comparative analysis of the center of pressure trajectory and plantar pressure distribution with different high-heeled shoes while standing on a dynamic surface with multidirectional perturbations. College females with at least 2 years' history of wearing high-heel shoes voluntarily participated in the test with a Novel Pedar insole (Novel, GmBH, Munich, Germany. With heels height increasing, the pressure time integral obviously transfer to the medial forefoot region, with center of pressure trajectory medially deviated significantly, either under anteroposterior or mediolateral perturbations. The passive plantarflexion position of ankle incurred by high heel increased the range of motion in the frontal plane but decreased ankle stability, thus increasing the challenge of body balance maintenance.     

Distance and Movement Time Effects on the Timing of Agonist and Antagonist Muscles

The experiment examined the effects of movement time (MT) and distance on the timing of electromyographic (EMG) activity from an agonist and antagonist muscle during rapid, discrete elbow movements in the horizontal plane. According to impulse-timing theory (Wallace, 1981) MT, not distance moved, should have a pronounced effect on the timing of EMG activity (duration of initial agonist and antagonist burst and time to onset of initial antagonist burst). The levels of MT were 100 and 160 msec and the levels of distance were 27° and 45° of elbow flexion. In general support of impulse-timing theory, the results of the three EMG timing measures showed that MT had a more pronounced effect on these measures than distance. In addition, the timing of EMG activity in relation to total MT remained fairly consistent across the four MT-distance conditions.     

Postural Asymmetries in Response to Holding Evenly and Unevenly Distributed Loads During Self-Selected Stance

The authors examined postural asymmetries during quiet stance and while holding evenly or unevenly distributed loads. Right-hand dominant subjects preferentially loaded their right lower limb when holding no load or a load evenly distributed in both hands, but no differences in center of pressure (CoP) were observed between the left and right limbs. However, longer CoP displacement was observed under the preferentially loaded limb, which may reflect a functional asymmetry that allows quick movement of one limb in response to a potential perturbation. When a load was held only in the nondominant hand, sample entropy decreased in the left (loaded) limb but increased in the right (unloaded) limb, suggesting the unloaded foot compensated for a loss of control flexibility in the loaded foot.     

Attention Is Required to Coordinate Reaching and Postural Stability during Upper Limb Movements Generated While Standing

Abstract

In the present study we investigated how attention contributes to the interaction between reach planning and execution, and postural control. Reaching movements were generated while standing and were performed either in isolation or in conjunction with a secondary reaction time (RT) task. In addition, to better understand how online movement control is affected by this interaction, the reaching movements could be unexpectedly perturbed medial-laterally. Postural kinetic, arm kinematic and RT, and secondary RT measures were used to characterize the responses. Results indicate task performance worsened when both the reaching and secondary tasks were completed simultaneously. Our results imply the generation of reaching movements while standing requires attentional resources to properly coordinate the interaction between the reaching task and postural control.     

Undisturbed Upright Stance Control in the Elderly: Part 2. Postural-Control Impairments of Elderly Fallers

A common way of predicting falling risks in elderly people can be to study center of pressure (CP) trajectories during undisturbed upright stance maintenance. By estimating the difference between CP and center of gravity (CG) motions (CP - CG_v), one can estimate the neuromuscular activity. The results of this study, which included 34 sedentary elderly persons aged over 75 years (21 fallers and 13 nonfallers), demonstrated significantly increased CG_h and CP - CG_v motions in both axes for the fallers. In addition, the fallers presented larger CG_h motions in the mediolateral axis, suggesting an enlarged loading—unloading mechanism, which could have reflected the adoption of a step-initiating strategy. As highlighted by fractional Brownian motion modeling, the distance covered by the CP - CG_v motions before the successive control mechanisms switched was enhanced for the fallers in both axes, therefore increasing the risk that the CG would be outside of the base of support.     

Unilateral Stability and Visual Feedback Body Control Improves After Three-Month Resistance Training in Overweight Individuals

The authors evaluated the effect of 3 months of resistance and aerobic training (3 sessions/week) on body balance in a group of 25 overweight and obese individuals. Prior to and after the training, they performed static and task-oriented balance tests under various conditions. Mean center of pressure (CoP) velocity and mean trace length of the CoP in the y-axis registered during a one-legged stance significantly decreased after the resistance training (19.1%, p = .024; 29.3%, p = .009). Mean trace length of the CoP in the y-axis decreased significantly also during a bipedal stance on a foam surface with eyes open and closed (10.9%, p = .040; 18.2%, p = .027). In addition, mean CoP distance and mean squared CoP distance in the anteroposterior direction during a visually guided center of mass (CoM) tracking task significantly improved (14.7%, p = .033; 28.2%, p = .016). However, only mean trace length of the CoP in the y-axis during a bipedal stance on a foam surface with eyes open and closed significantly decreased after the aerobic training (10.3%, p = .047; 16.5%, p = .029). It may be concluded that resistance training is more efficient for the improvement of the anteroposterior unilateral stability and the accuracy of the regulation of the CoM anteroposterior position than aerobic training in overweight and obese individuals.     

Center of Gravity Motions and Ankle Joint Stiffness Control in Upright Undisturbed Stance Modeled Through a Fractional Brownian Motion Framework

The authors modeled the center of gravity vertical projection (CG_V) and the difference, CP - CG_V, which, combined, constitute the center of pressure (CP) trajectory, as fractional Brownian motion in order to investigate their relative contributions and t heir spatiotemporal articulation. The results demonstrated that CG_V and CP - CG_V motions are both endowed in complementary tashion with strong stochastic and part-deterministic behaviors. In addition, if the temporal coordinates remain similar for all 3 trajectories by definition, the switch between the successive control mechanisms appears for shorter displacements for CP - CG_V and CG_V than for CP trajectories. Results deduced from both input (CG,) and muscular stiffness (CP - CG_V) thus provide insight into the way the central nervous system regulates stance control and in particular how CG and CP - CG are controlled.     

Age-Related Changes in the use of Study Context to Increase Recollection

ABSTRACT

We examined how context presented at study affects recollection of words in younger and older adults. In Experiment 1, participants studied words presented with a picture of a face (context-rich condition) or a rectangle (context-weak condition), and subsequently made ‘Remember’, ‘Know’, or ‘New’ judgments to words presented alone. Younger, but not older, adults showed higher Remember accuracy following rich- than weak-context trials. In Experiment 2, we manipulated the type of processing engaged during the encoding of context–word pairs. Younger and older adults studied words presented with a picture of a face under a surface feature (gender) or binding feature (match) instruction condition. Both age groups showed higher Remember accuracy in the binding than surface instruction condition. Results suggest that providing rich contextual detail at encoding boosts later item recollection in younger adults. Older adults, however, do not spontaneously engage in the processes required to boost recollection, though instructional manipulation during encoding lessens this deficit.     

从大众传媒看公众对安乐死态度的嬗变

安乐死问题在我国已经历了由精英话语向大众话题的转变。研究传媒的相关报道 ,可以看出公众对安乐死问题经过认知、态度转变到实践的历程 ,通过分析传媒对塑形公众观念所起的作用 ,可以更好地把握当代社会公众接受新生命伦理观的过程     

对高血压诊治的现象与本质的关系反思——聚焦血压变化与心脑肾血液灌注量的关系

高血压和低血压都存在急性状态和慢性状态,在急性状态,高血压表现为血流高灌注,低血压表现为血流低灌注;而在慢性状态,高血压和低血压则表现出共同的特点——血流低灌注。血压数值只是个表面现象,重要的是透过血压数值的变化去探究血压变化背后的病理生理改变,尤其是血压变化与重要脏器血液灌注量多少的关系,治疗的最终目的是维持人体脏腑器官一定的血流量,而不是仅仅满足于发现并治疗患者所表现出来的血压数值。     

《易》象与《诗》象:论《周易》的类艺术表现方式

文章从符号学角度,通过《诗》《易》比较,论述了《周易》的类艺术特征。在构成符号的综合性上,在篇章的结构、句式词语的使用上,在物象选择与深层意蕴上,《易》和《诗》具有异质同构的关系。后世艺术作品中出现的同类意象,其原型可溯到《诗》,更可求诸《易》。     

From Inexactness to Certainty: The Change in Hume's Conception of Geometry

Although Hume's analysis of geometry continues to serve as a reference point for many contemporary discussions in the philosophy of science, the fact that the first Enquiry presents a radical revision of Hume's conception of geometry in the Treatise has never been explained. The present essay closely examines Hume's early and late discussions of geometry and proposes a reconstruction of the reasons behind the change in his views on the subject. Hume's early conception of geometry as an inexact non-demonstrative science is argued to be a consequence of his attempt to discredit geometrical proofs of infinite divisibility of extension by anchoring the meaning of geometrical concepts in inherently inexact qualitative measurement procedures. This measurement-based attack on the exactness and certainty of geometry is analyzed and shown to be both self-refuting and inconsistent with the general epistemological framework of the Treatise. The revised conception of geometry as a demonstrative science in the first Enquiry is then interpreted as Hume's response to the failure of his earlier attempt to discredit geometrical proofs of infinite divisibility of extension. This revised version was published online in August 2006 with corrections to the Cover Date.     

Two Factors to be Considered in the Design of Experiments in Anxiety and Motor Behavior

The authors examined the influence that attentional focus on either a postural or a suprapostural task had on the performance of each task. Participants (N = 32) stood on an inflated rubber disk and held a pole horizontally. All participants performed under 4 attentional focus conditions: external (disk) or internal (feet) focus on the postural task, and external (pole) or internal (hands) focus on the suprapostural task. Compared with internal focuses, external focuses on either task resulted in similar and reduced postural sway. Response frequency on each task increased when participants focused on the respective task. Finally, an external focus on either task produced higher frequencies of responding on the suprapostural task. The authors conclude that suprapostural task goals have a stronger influence on postural control than vice versa, reflecting the propensity of the motor system to optimize control processes on the basis of the desired movement effect.     

从冠心病主要危险因素的流行特点谈医学模式的转变

随着人民生活水平的提高,冠心病的发病率呈逐年上升趋势,不仅造成个人很高的致残率或致死率,而且给家庭和社会带来沉重的经济负担,冠心病已成为当前一个重要的公共卫生问题。而冠心病是一个多病因疾病,是可防可控的。充分了解冠心病危险因素的流行现状及危害,转变理念,着眼预防,逐步改变目前"重治轻防"的医学模式,是我们心血管医生神圣的使命。     

From case management to prevention of scientific dishonesty in Denmark

In 1992, The Danish Medical Research Council established a national committee on scientific dishonesty with the twofold task of handling cases of scientific misconduct and taking preventive initiatives. Scientific dishonesty was proven in only five cases, but in another nine cases lesser degrees of deviations from good scientific practice were found. The experiences from a total of 24 treated cases indicated that three key areas were at the basis of most of the accusations and the deviations from good practice: uncertainty about 1) authorship, about 2) rights and duties to use scientific data and about 3) agreements at the initiation of joint studies. As a consequence guidelines on good practice have been issued on these key subjects. An earlier version of this paper was presented at a symposium, Scientific Misconduct. An International Perspective, organised by The Medical University of Warsaw, 16 November, 1998.     

From Prophecy to Practice: Mutual Selection Cycles in the Routinization of Charismatic Authority

We examine how culture and structure intersect in mediating competing claims to authority during the routinization of charisma. Using archival data, we trace the mechanisms of routinization in the early Church of Jesus Christ of Latter Day Saints during the succession crisis that followed the death of the prophet Joseph Smith in 1844, which resulted in the ascension of a new leader and shaped the institutional development of the religion. Combining in‐depth historical analysis and social network analysis, we identify key processes that led to the ultimate resolution of the crisis. These processes show that the way church members interpreted and enacted prophecies and theological teachings directly affected social networks within the community. In turn, this increased the importance of these particular teachings within the community and in the religious organization in a cycle that shaped the social mechanisms of the crisis resolution. Generalizing our findings, we introduce the concept of mutual selection cycles as a framework for explaining how prophecy and practice interact in institutionalizing charismatic authority.     

从认知范式到人本范式 --创造性心理学研究范式的整体性转型

长期以来,认知范式创造性心理学将研究的重心放在个体创造性思维的发散性运演与转化上,排斥价值性研究。而人本范式创造性心理学将研究重心放在个体的人性建设上,从根本上实现了创造性心理学研究范式的整体性转型。本文对人本范式创造性心理学的哲学基础、主要观点、方法论思想、影响及局限作了简明扼要的阐释。     

Revising Method in Psychological Studies of Religious Matters: From Repeating to Remembering and Working-Through

Fundamental criticisms of research in psychology of religion are recurrently leveled by scholars—including psychologists of religion themselves: the character, intention, and validity of many studies are suspect; approaches are parochial; findings are often insubstantial. These valid critiques betray a neglected root cause: a problem of method. This essay examines method and method change, considers why inadequate methods persist as well as how operative methods are corrected. It identifies tacit problematic commitments and outlines contours of a revised method.