Do age and work pace affect variability when performing a repetitive light assembly task?

This study examined whether a repetitive light assembly task could be performed according to different movement sequences identified as ways of doing (WoD), and whether the age of the participants or the work pace affected the number of WoDs selected by each participant, or the kinematic parameters for each WoDs. For two work paces, 62 right-handed men in 3 age-groups were asked to fix a handle on a base with 2 nuts without discontinuity for a period of 20 min; no assembly procedure was demonstrated. The WoDs were characterized by a cross tabulation video coding method, and by measuring vertical force applied and the parameters of upper limb kinematics, as well as these measures' approximate entropy (ApEN).

Evidence of movement variability patterns during a repetitive pointing task until exhaustion.

Human movement is characterized by its variability: the same task is never performed twice in exactly the same way. This variability is believed to play a functional role in movement performance and adaptability, as well as in preventing musculoskeletal damage. This article focuses on the time-evolution of movement variability throughout a repetitive pointing task until exhaustion.

Which subject-related variables contribute to movement variability during a simulated repetitive and standardised occupational task? Recurrence quantification analysis of surface electromyographic signals.

Movement variability is a component of human movement. This study applied recurrence quantification analysis (RQA) on electromyographic signals to determine the effects of two types of variables on movement variability during a short, simulated repetitive and standardised occupational clip-fitting task. The electrical activity of six muscles in the dominant upper limb was recorded in 21 participants.

Study of between-subject and within-subject variability of electromyography data and its intrinsic determinants for clip fitting tasks.

Knowledge of motor variability is an essential step towards understanding a subject's working activity. This study aims to assess within-subject and between-subject variability and the intrinsic factors that drive variability during a clip fitting task in the laboratory. Muscular activity is recorded on six muscles of each upper limb.

Effects of mouse slant and desktop position on muscular and postural stresses, subject preference and performance in women aged 18-40 years.

This study compared muscular and postural stresses, performance and subject preference in women aged 18-40 years using a standard mouse, a vertical mouse and a slanted mouse in three different computer workstation positions. Four tasks were analysed: pointing, pointing-clicking, pointing-clicking-dragging and grasping-pointing the mouse after typing. Flexor digitorum superficialis (FDS) and extensor carpi radialis (ECR) activities were greater using the standard mouse compared to the vertical or slanted mouse.

Intrinsic movement variability at work. How long is the path from motor control to design engineering?

For several years, increasing numbers of studies have highlighted the existence of movement variability. Before that, it was neglected in movement analysis and it is still almost completely ignored in workstation design. This article reviews motor control theories and factors influencing movement execution, and indicates how intrinsic movement variability is part of task completion.

A better way of fitting clips? A comparative study with respect to physical workload.

The clip fitting task is a frequently encountered assembly operation in the car industry. It can cause upper limb pain. During task laboratory simulations, upper limb muscular activity and external force were compared for 4 clip fitting methods: with the bare hand, with an unpowered tool commonly used at a company and with unpowered and powered prototype tools.

Similarities between work related musculoskeletal disorders and slips, trips and falls.

Most occupational risks manifest themselves through movements performed at work, for example musculoskeletal disorders, slips, trips and falls. Research focusing on such risks often differentiates diseases from accidents. All these risks prove to be diffuse, widespread, emergent and devoid of an external harmful hazard, when analysed through their common vector, i.

Modelling gait processes as a combination of sensory-motor and cognitive controls in an attempt to describe accidents on the level in occupational situations.

In occupational situations, accidents referred to as accidents on the level (AoLs) occur most of the time when locomotion control fails. This control is determined by the interactions between the operator and the environment, the task and the used tools. Hence, AoLs prevention requires developing ways to optimise these interactions.

Determination of joint efforts in the human body during maximum ramp pushing efforts.

Determining with accuracy, the internal efforts in the human body is a great challenge in Biomechanics, particularly in Physical Therapy and Ergonomics. In this context, the present study develops a human body model that permits a non-invasive determination of the joint efforts produced by a seated subject performing maximum ramp pushing efforts. The joint interactions during these experiments are provided by a dynamic inverse model of the human body, using a symbolically generated recursive Newton-Euler formalism.

Significance of circulating T-cell clones in Sezary syndrome.

Identification of malignant Sézary cells by T-cell receptor (TCR) clonality studies is routinely used for the diagnosis of Sézary syndrome, but T-cell clones expressed in a single patient have never been accurately characterized. We previously reported that CD158k expression delineates Sézary syndrome malignant cells, and, more recently, we identified vimentin at the surface membranes of Sézary cells and normal activated lymphocytes. In the present study, T-cell clones from 13 patients with Sézary syndrome were identified by immunoscopy and further characterized in the blood according to their TCR Vbeta, CD158k, and vimentin cell-surface expression.

Does support surface coefficient of friction influence postural dynamics and isometric force productions of the upper extremities performed by seated subjects?

The purpose of this study is to determine if increasing the potential risk of slipping on support surface materials decreases postural dynamics and task performance. Seated subjects were asked to exert maximum horizontal two-handed isometric pushes as quickly as possible on a dynamometric bar. Reaction forces exerted at seat (Rxs and Rzs) and footrest (Rxf and Rzf) were measured using force sensors.

[Livedo-like dermatitis (Nicolau's syndrome) after injection of Copolymer-1 (Glatiramer acetate)].

We report the first case of a 33-year-old woman with multiple sclerosis, who developed a livedo-like dermatitis after injection of Copolymere-1. This disease is characterized by the development of acute violent pain during or immediately after injection, and a livedo-like plaque followed by necrosis corresponding to an arterial ischemia by vasospasm or thrombosis. Early treatment with vasoactive and anticoagulation agents is required.