1. Research assistant, Department of Anaesthesia, University of Helsinki, Helsinki, Finland
2. Professor of Anaesthesia, Helsinki University Central Hospital, Helsinki, Finland
3. Research assistant, Department of Pharmacology, University of Helsinki, Helsinki Finland
4. Industrial hygienist, Department of Industrial Hygiene and Toxicology, Institute of Occupational Health, Helsinki, Finland
5. Research assistant, Department of Psychology, Institute of Occupational Health, Helsinki, Finland
6. Professor of Industrial Psychology, Helsinki University of Technology, Espoo, Finland