Work-related psychosocial,physical and individual factors associated with musculoskeletal symptoms in computer users

The aim of this study was to study associations between psychosocial, physical and individual factors, and musculoskeletal symptoms in the neck, shoulder and hand/wrist regions of computer users. Questionnaires were distributed to 5033 employees in 11 Danish companies; these employees all used computers for at least some of their work time. The response rate was 69% ( n = 3475). The analyses were based on employees working 32-41 h/week ( n = 2579). Symptomatic respondents reported symptoms for at least 8 days within the previous year. Multiple logistic regression analyses were used. Gender (female), age and duration of employment in the same job were associated with an increased prevalence of symptoms. High quantitative job demands and low possibilities for development at work were predictors of neck and hand/wrist symptoms. A high degree of repetitiveness and disturbing reflections on the computer screen were associated with symptoms in all three body regions. Repetitive movements were defined as the same finger, hand or arm movements performed many times per minute for at least 75% of their work time. Repetitiveness was the only factor that could partly explain associations between symptoms and duration of computer use, i.e. respondents who used the computer almost all the time at work reported more repetitive movements than those who used it less. Thus, long hours of computer use may be associated with musculoskeletal symptoms, due to physical factors such as repetitive movements, whereas psychosocial factors appeared to be associated with the symptoms independently of the duration of computer use.     

Minicommunications

This section of the periodical is reserved for Conclusions (Results), Comments, Conjectures, and Microcommunications. Contributions will be welcomed and might even be printed!     

OPTIMAL ALLOCATIONS OF JOINT (COMMON) COSTS: A PARAMETRIC PROGRAMMING APPROACH

A parametric programming model for allocating joint costs is described and illustrated. Given M mutually exclusive missions and P alternative systems for accomplishing such missions, the model first determines the optimal choice of systems for all missions simultaneously. It then allocates both joint and separable costs such that no mission receives a greater cost allocation than any other mission alternative that might be suboptimal for the mission but nonoptimal when all missions are simultaneously considered. Although the model initially assumes a mission priority ranking, this assumption is relaxed later on as alternative rankings are evaluated and cost allocation ranges under all priority rankings are evaluated.     

Collateral Avoids Ponzi Schemes in Incomplete Markets

Without introducing either debt constraints or transversality conditions to avoid the possibility of Ponzi schemes, we show the existence of equilibrium in an infinite horizon incomplete markets economy with a collateral structure.