Dynamic Visual Acuity and Performance in a Catching Task

Each of 30 Ss was given tests of dynamic and static visual acuity and then participated in a ball-catching task. Performance in the latter task was an inverted U-shaped function of duration of the occluded period, the time between the termination of the 80-msec. viewing period and the estimated onset of the “latency period” (the point in time at which the ball could no longer serve to cue Ss response). Dynamic and static visual acuity scores were not significantly correlated but, with static visual acuity partialled out, dynamic visual acuity and catching performance were significantly correlated.     

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.     

Assume a Spherical Chicken: Analytic Constraints,Inertia Tensor Information,and Wielded Rod Length Perception

Information associated with the inertia tensor is the preeminent explanation for haptic perception of object properties, notably wielded rod length. Critics counter that tensorial-based information requires non-tensorial supplementation (mass, torque). However, those critiques omit important constraints. With relevant constraints included, the inertia tensor alone completely specifies rod length. I list constraints inherent (but tacit) in haptic rod length perception, and show that object properties associated with the inertia tensor are invariant, even with constraints removed, by involving (a) longitudinal moment equivalents for rod mass and (b) derivatives of moments with respect to varying rotation axes. Analytic outcomes show tensorial-based information is a robust basis for wielded rod length perception, and suggest open questions for empirical exploration.     

Local Dynamic Stability of the Locomotion of Lower Extremity Joints and Trunk During Backward Upslope Walking

Backward slope walking was considered as a practical rehabilitation and training skill. However, its gait stability has been hardly studied, resulting in its limited application as a rehabilitation tool. In this study, the effect of walking direction and slope grade were investigated on the local dynamic stability of the motion of lower extremity joints and trunk segment during backward and forward upslope walking (BUW/FUW). The local divergence exponents (λ_S) of 16 adults were calculated during their BUW and FUW at grades of 0%, 5%, 10%, and 15%. Mean standard deviation over strides (MeanSD) was analyzed as their gait variability. Backward walking showed larger λ_S for the abduction-adduction and rotational angles of knee and ankle on inclined surface than forward walking, while λ_S for hip flexion-extension angle at steeper grades was opposite. No grade effect for any joint existed during BUW, while λ_S increased with the increasing grade during FUW. As to the trunk, walking direction did little impact on λ_S. Still, significant larger λ_S for its medial-lateral and vertical motion were found at the steeper grades during both FUW and BUW. Results indicate that during BUW, the backward direction may influence the stability of joint motions, while the trunk stability was challenged by the increasing grades. Therefore, BUW may be a training tool for the stability of both upper and lower body motion during gait.     

Estimating Gait Stability: Asymmetrical Loading Effects Measured Using Margin of Stability and Local Dynamic Stability

Changes to intersegmental locomotor control patterns may affect body stability. Our study aimed to (a) characterize upper body dynamic stability in response to the unilateral addition of mass to the lower extremity and (b) evaluate the efficacy of 2 different stability measures commonly used in the literature to detect resulting symmetrical step pattern modifications across the weighted segments (spatial) and between epochs of the gait cycle (temporal). Young adults walked on a treadmill while unloaded or with weights applied unilaterally to their foot, shank, or thigh. Both margin of stability and local dynamic stability (LDS) estimates detected similar trends of distal segment weighting resulting in more unstable upper body movement compared to proximal weighting; however only LDS detected anteroposterior changes in upper body stability over time.     

Opportunities and Issues in Modeling Intensive Longitudinal Data: Learning from the COGITO Project

Abstract

Technological developments increasingly permit the collection of longitudinal data sets in which the data structure contains a large number of participants N and a large number of measurement occasions T. Promising new dynamical systems approaches to the analysis of large N, large T data sets have been proposed that utilize both between-subjects and within-subjects information. The COGITO project, begun over a decade ago, is an early large N?=?204, large T?=?100 study that collected high quality cognitive and psychosocial data. In this introduction, I describe the COGITO project and conceptual and statistical issues that arise in the analysis of large N, large T data sets. I provide a brief overview of the five papers in the special section which include conceptual pieces, a didactic presentation of a dynamic structural equation approach, and papers reporting new statistical analyses of the COGITO data set to answer substantive questions. Although many challenges remain, these new approaches offer the promise of improving scientific inquiry in the behavioral sciences.     

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.     

The Impact of Early Loss on Depression

Abstract

This article reviews psychodynamic theoretical claims linking childhood losses to depression later in life and explores contemporary empirical studies that are congruent with those claims. Biologically mediated responses to grief, empirically supported pathways that link loss to depression, and factors that distinguish normal from pathological grief are identified. Trajectories that may lead to the development of psychotic-like, instead of neurotic-like, symptoms of depression are also explored, and empirically supported internal and external vulnerability factors that may lead to depression are reported. Several clinical vignettes are included to exemplify theoretical claims. Implications for assessment and treatment are discussed in light of these findings.