Repeated Exposure to Forward Support-Surface Perturbation During Overground Walking Alters Upper-Body Kinematics and Step Parameters

Locomotion requires both proactive and reactive control strategies to maintain balance. The current study aimed to: (i) ascertain upper body postural responses following first exposure to a forward (slip) support-surface perturbation; (ii) investigate effects of repeated perturbation exposure; (iii) establish relationships between arms and other response components (trunk; center of mass control). Young adults (N = 11) completed 14 walking trials on a robotic platform; six elicited a slip response. Kinematic analyses were focused on extrapolated center of mass position (xCoM), bilateral upper- and forearm elevation velocity, trunk angular velocity, and step parameters. Results demonstrated that postural responses evoked in the first slip exposure were the largest in magnitude (e.g., reduced backward stability, altered reactive stepping, etc.) and preceded by anticipatory anterior adjustments of xCoM. In relation to the perturbed leg, the large contra- and ipsilateral arm responses observed (in first exposure) were characteristically asymmetric and scaled to the degree of peak trunk extension. With repeated exposure, xCoM anticipatory adjustments were altered and in turn, reduced posterior xCoM motion occurred following a slip (changes plateaued at second exposure). The few components of the slip response that persisted across multiple exposures did so at a lesser magnitude (e.g., step length and arms).     

Nonlinear approach to study the acute effects of static and dynamic stretching on local dynamic stability in lower extremity joint kinematics and muscular activity during pedalling

Researchers have reported contradictory results on the effect of static and dynamic stretching on subsequent performance. Due to the importance of performance through static and dynamic stretching, the aim of this study is to investigate the acute effects of static and dynamic stretching protocols on local dynamic stability in lower extremity joint kinematics and muscular activities during pedalling using a nonlinear dynamics approach. Using a randomised crossover trial design, fifteen active males participated voluntarily in this research (mass: 69.02 ± 10.52 kg, height: 174.00 ± 6.74 cm, and age: 21.20 ± 1.47 years) and completed a pedalling trial in situations of without stretching (WS), after static (SS), and dynamic stretching (DS) of lower extremity. The lower extremity joint angles in the sagittal plane and the electrical activity of soleus, gastrocnemius medialis, tibialis anterior, vastus medialis, biceps femoris, and rectus femoris muscles were collected during 30 pedalling cycles at 70 rates per minute. The results of the repeated measure ANOVA indicated that the knee and ankle angle largest LyE was significantly lower in DS compared to WS and SS. The largest LyE in muscle activity is also significantly lower for all the muscles after DS compared to WS and SS (P ≤ 0.05). Regarding the positive effects of DS on the joints and the muscle activity local dynamic stability, it is suggested to use DS than SS in the warm-up program before repetitive activities like pedalling.     

一个新的中医研究范式:从非线性动力学的角度解读中医

西方对中医的研究多是利用随机控制试验来检验其疗效。通过讨论,认为这类研究有其局限性。同时探讨一种新的研究范式,即非线性动力学理论。认为这一理论能够提供理论依据来设计适合中医特征的临床试验,并可望得出为西方医学界所接受的研究结果。     

动态文本最优化呈现的眼动研究

采用2（呈现方式：平滑滚动引导式、RSVP）×5（呈现速度：120、240、360、480、600字/分）×3（窗口大小：5、10、15字）的多因素混合实验设计,运用EyelinkⅡ眼动仪对汉语动态文本阅读过程进行研究。结果发现,呈现速度较快（≥360字/分）时,与RSVP条件相比,被试在平滑滚动引导式条件下的平均注视时间短、注视次数多、眼跳距离小,阅读理解率高,且被试更偏爱此种呈现方式;呈现速度较慢（≤240字/分）时,两种呈现方式在平均注视时间和注视次数上没有差异。在平滑滚动引导式下,被试在三种窗口大小中各项指标上没有差异;在RSVP条件下,与5字窗口相比,大窗口（10字或15字）条件下平均注视时间更短。     

Studying the Dynamics of Problem Behavior Across Multiple Time Scales: Prospects and Challenges

As a commentary on the Special Issue, this paper discusses recent advances in the study of change across several time scales. It points out the importance of specifying time scales and putative patterns of change when characterizing problem behavior over developmental time scales. Methods for studying risk and protective mechanisms through observation of social interaction are also discussed as a way to study influences that operate in real time. Methods for studying episode-level interaction patterns that result from such real-time influences are also discussed, along with ways to integrate these with longitudinal assessments to study the effects of social interaction on problem behavior across developmental time scales.     

Infant perceptual and conceptual categorization: the roles of static and dynamic stimulus attributes

Infants' categorization of animals and vehicles based on static vs. dynamic attributes of stimuli was investigated in five experiments (N=158) using a categorization habituation-of-looking paradigm. In Experiment 1, 6-month-olds categorized static color images of animals and vehicles, and in Experiment 2, 6-month-olds categorized dynamic point-light displays showing only motions of the same animals and vehicles. In Experiments 3, 4, and 5, 6- and 9-month-olds were tested in an habituation-transfer paradigm: half of the infants at each age were habituated to static images and tested with dynamic point-light displays, and the other half were habituated to dynamic point-light displays and tested with static images. Six-month-olds did not transfer. Only 9-month-olds who were habituated to dynamic displays showed evidence of category transfer to static images. Together the findings show that 6-month-olds categorize animals and vehicles based on static and dynamic information, and 9-month-olds can transfer dynamic category information to static images. Transfer, static vs. dynamic information, and age effects in infant categorization are discussed.     

Disjunctive Quantum Logic in Dynamic Perspective

In Coecke (2002) we proposed the intuitionistic or disjunctive representation of quantum logic, i.e., a representation of the property lattice of physical systems as a complete Heyting algebra of logical propositions on these properties, where this complete Heyting algebra goes equipped with an additional operation, the operational resolution, which identifies the properties within the logic of propositions. This representation has an important application towards dynamic quantum logic, namely in describing the temporal indeterministic propagation of actual properties of physical systems. This paper can as such by conceived as an addendum to Quantum Logic in Intuitionistic Perspective that discusses spin-off and thus provides an additional motivation. We derive a quantaloidal semantics for dynamic disjunctive quantum logic and illustrate it for the particular case of a perfect (quantum) measurement.     

Effect of Mg content on Portevin–Le Chatelier band strain in Al–Mg sheet alloys

Experimental measurements of stress drops and band strains in type-B Portevin–Le Chatelier (PLC) bands were carried out for 5xxx series Al–Mg sheets with Mg content between 1.8 and 4.5?wt%. While the stress drops increase with global strain, the band strain values in all the samples follow a common linear relationship with global strain. The results indicate that the type-B PLC band strain is independent of solute content at given strain rate.     

Many-body potential for nitrogen in α-iron

N atom is one of the most frequent foreign interstitial atoms in α-iron along with C atoms. The Fe–C potential has been well-developed and can reproduce many significant interactions of C with point defects present in α-iron. However, there exists no satisfactory Fe–N potential to describe the interactions of N with point defects. Here, we develop a many-body potential for N in α-iron. The potential parameters are determined by fitting to ab initio data, which includes energetics, configurations, and relaxations of Fe atoms close to N atom. This potential successfully describes the interactions of Fe–N across a wide range of defect environments. The potential employs the embedded atom method form and hence is appropriate for large-scale molecular dynamics simulation.     

Suitability and context for brief therapy

Abstract

The main point of this paper is that a client's suitability for brief or time-limited therapy is determined by various factors, including context. There is still agreement on the validity of Malan's selection criteria, which included ‘mild illness, recent onset, high motivation and response to trial interpretation’, yet many additional issues have since emerged and need to be considered. For instance, the counsellor's suitability, training and work experience, the counsellor's assessment skills and ability to establish a dynamic focus, the clients' capacity for self-reflection, their ego strength and their response to a trial therapy in the first session. Then there is the importance of the various contexts in which nowadays much brief counselling is offered free to clients, whether in education, at the workplace, in primary healthcare settings or by charitable organizations. This means that issues of money and markets have come to the fore and an initial differential assessment needs to be carried out in order to decide which method or model of therapy is best for the client. Matching the counsellor's personality to the needs and to the pathology of the client, and matching the treatment to the client's developmental stage or life stage crises are other aspects of the work, which determine the issue of suitability. In the end as always there is much that remains unknown about what works for whom and how the client's decision to take up help is made.