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Physical fitness and other individual factors relating to the shiftwork tolerance of women
clear practical optimum exists for mean or peak power outputs as a function of load, and that both peak and mean power are closely related to sprint performance times. 20.4.10 (112156)
Eklund, J.A.E. Body height changes as a measure of spinal loads and properties of the spine. In: Ergonomics in Rehabilitation, A. Mital and W. Karwowski (Eds). Taylor & Francis, Philadelphia, 1988, pp 1 9 9 - 2 1 0 , 31 refs. The shrinkage method has recently been developed for assessment of spinal loads and properties of the spine. Using precise measurements of body height changes, the viscous disc compression, or disc creep, can be assessed. In this paper, the method, the equipment and the procedure used are described. It was shown that the contribution to the b o d y height reduction from structures other than the spine is negligible in relation to the contribution from the spine. It has also been shown that the body height shrinkage is well correlated with spinal loads, and that the method is sensitive enough to differentiate between spinal loads of 100 N difference. Other studies have demonstrated that the shrinkage is also related to the perception of discomfort. The method can be used not only for evaluation of spinal loads or effects of spinal loads, arising from different activities, postures and workplace equipment, but also for evaluation of treatment methods. Finally, it can also be used to assess different individual properties, with respect to shrinkage when subjected to standardised loadings. 20.4.11 (112161)
Imrhan, S.N., and Loo, C.H. Modelling wrist-twisting strength of the elderly. Ergonomics, 1988, 31.12, 1 8 0 7 - 1 8 1 9 , 16 refs. This paper presents a biomechanical model of wrist-twisting strength and uses it to explain maximum voluntary contractile (MVC) counterclockwise torque and force generated by elderly subjects in attempting to unscrew rough and smooth circular screw-type container lids of diameters 31, 55, 74 and 113 mm. Forty-two subjects, aged 6 0 - 9 7 years, were tested. The results indicated that, for commercially available lids, torquediameter relationship was linear up to a certain lid size (diameter), and nonlinear, with a decreasing trend, beyond that size. The non-linearity was different for lids with rough and smooth grip surfaces. An optimal diameter for smooth lids has been proposed. For both types of grip surface, force magnitudes were similar up to 74 mm. Beyond this
322
Applied Ergonomics
diameter the effects of surface finish were manifested. This was explained by the relationship between hand size and type of grip used at various diameters. Implications of these results for lid design are discussed. Regression models are also presented which portray good fit to the data.
In different shifts, fatigue, sleep length and quality were influenced mostly by momingness. It is concluded that physical fitness is an important ifidividual factor explaining the variations of shiftwork tolerance in women.
20.4.12 (112165)
Passini, R., and Proulx, G.
Mital, A., and Channaveeraiah, C.
Building access and safety for the visually impaired person. In: Safety in the Built Environment, J.D. Sime (Ed). E. & F.N. Spon, London, 1988, pp 1 1 6 - 1 2 9 , 30 refs.
20.4.14 (112226) Peak volitional torques for wrenches and screwdrivers. In t J lndust Ergonomics, 1988, 3 . 1 , 4 1 - 6 4 , 52 refs. Effects of grip shape (regular, circular, square and triangular) , wrist orientation (three for screwdrivers and seven for wrenches) and duration of repeated exertions on the maximum torque males and females could exert in different postures with four wrenches and four screwdrivers were investigated experimentally. Quantitative data were collected by conducting two independent sequential experiments. Circular grips for wrenches and triangular grips for screwdrivers maximised torque exertion capability. The peak torque declined with the duration of repeated exertions but stabilised after 180 s. Wrist orientation also had a significant influence on how much torque individuals could exert. A third experiment generated torque data for two additional body postures that were not included in previous works. From this investigation, correction factors were developed to generate peak torque exertion capability data of individuals with wrenches and screwdrivers for a variety of conditions dictated .by body posture, wrist orientation, duration of repeated exertions, and grip shape. The paper includes the basic torque exertion capability design data tables and the correction factors. 20.4.13 (112219)
Harma, M., Ilmarinen, J., and Knauth, P. Physical fitness and other individual factors relating to the shiftwork tolerance of women. Chronobiol Int, 1988, 5 . 4 , 4 1 7 - 4 2 4 , 28 refs. Maximal oxygen consumption (VO2 max), muscle strength (MS) and physical activity were compared with age, shiftwork experience, momingness, personality traits and social factors intervening in the shiftwork tolerance of 128 women. The subjects were nurses and nursing aids working irregular shifts in a hospital. Neuroticism was the most powerful negative factor connected to higher fatigue and various symptoms of the subjects. High VO 2 max and good MS were, on the other hand, the most important positive factors connected to lower fatigue and musculo-skeletal symptoms and better sleep quality of the subjects.
December 1989
The paper summarises three studies on wayfinding and the underlying spatio-cognitive skills of the visually impaired. The results suggest equivalent spatio-cognitive skills for all types of visual impairment, including the congenitally totally blind. A survey showed that public buildings are generally only accessible to a small proportion of blind visitors. It is argued that the key problem is one of access to information and that by designing adequate information systems, efficient wayfinding behaviour can be supported. By making buildings accessible to the blind population, new questions of safety and security emerge. Based on the above research, ideas for making buildings both accessible and safe are suggested° 20.4.15 (112237)
Knauth, P., Condon, R., Colquhoun, W.P., Plett, R., Sehmidt, K.H., and Rutenfranz, J. Alertness of watchkeeping personnel during long distance ship voyages. In: Vigilance: Methods, Models and Regulation, J.P. Leonard (Ed). Verlag Peter Lang, Frankfurt am Main, 1988, pp 9 1 - 9 8 , 22 refs. Four-hourly alertness ratings from 25 subjects on five ships were analysed. Individual subjects were studied over a period of between 3 and 13 days. The data showed circadian variation with the greatest impairment of alertness at 0400 h. Alertness improved from the beginning to the end of each watch during the first half of the day, and declined over each watch during the second half of the day, 20.4.16 (112265)
Meshkati, N., and Loewenthal, A. An eclectic and critical review of four primary mental workload assessment methods: A guide for developing a comprehensive model. In: Human Mental Workload, P.A. Hancock and N. Meshkati (Eds). North-Holland, Amsterdam, 1988, pp 2 5 1 - 2 6 7 , 85 refs. Four primary methods of mental workload assessment - i e, secondary task, subjective rating, performance
Eklund, J.A.E. Body height changes as a measure of spinal loads and properties of the spine. In: Ergonomics in Rehabilitation, A. Mital and W. Karwowski (Eds). Taylor & Francis, Philadelphia, 1988, pp 1 9 9 - 2 1 0 , 31 refs. The shrinkage method has recently been developed for assessment of spinal loads and properties of the spine. Using precise measurements of body height changes, the viscous disc compression, or disc creep, can be assessed. In this paper, the method, the equipment and the procedure used are described. It was shown that the contribution to the b o d y height reduction from structures other than the spine is negligible in relation to the contribution from the spine. It has also been shown that the body height shrinkage is well correlated with spinal loads, and that the method is sensitive enough to differentiate between spinal loads of 100 N difference. Other studies have demonstrated that the shrinkage is also related to the perception of discomfort. The method can be used not only for evaluation of spinal loads or effects of spinal loads, arising from different activities, postures and workplace equipment, but also for evaluation of treatment methods. Finally, it can also be used to assess different individual properties, with respect to shrinkage when subjected to standardised loadings. 20.4.11 (112161)
Imrhan, S.N., and Loo, C.H. Modelling wrist-twisting strength of the elderly. Ergonomics, 1988, 31.12, 1 8 0 7 - 1 8 1 9 , 16 refs. This paper presents a biomechanical model of wrist-twisting strength and uses it to explain maximum voluntary contractile (MVC) counterclockwise torque and force generated by elderly subjects in attempting to unscrew rough and smooth circular screw-type container lids of diameters 31, 55, 74 and 113 mm. Forty-two subjects, aged 6 0 - 9 7 years, were tested. The results indicated that, for commercially available lids, torquediameter relationship was linear up to a certain lid size (diameter), and nonlinear, with a decreasing trend, beyond that size. The non-linearity was different for lids with rough and smooth grip surfaces. An optimal diameter for smooth lids has been proposed. For both types of grip surface, force magnitudes were similar up to 74 mm. Beyond this
322
Applied Ergonomics
diameter the effects of surface finish were manifested. This was explained by the relationship between hand size and type of grip used at various diameters. Implications of these results for lid design are discussed. Regression models are also presented which portray good fit to the data.
In different shifts, fatigue, sleep length and quality were influenced mostly by momingness. It is concluded that physical fitness is an important ifidividual factor explaining the variations of shiftwork tolerance in women.
20.4.12 (112165)
Passini, R., and Proulx, G.
Mital, A., and Channaveeraiah, C.
Building access and safety for the visually impaired person. In: Safety in the Built Environment, J.D. Sime (Ed). E. & F.N. Spon, London, 1988, pp 1 1 6 - 1 2 9 , 30 refs.
20.4.14 (112226) Peak volitional torques for wrenches and screwdrivers. In t J lndust Ergonomics, 1988, 3 . 1 , 4 1 - 6 4 , 52 refs. Effects of grip shape (regular, circular, square and triangular) , wrist orientation (three for screwdrivers and seven for wrenches) and duration of repeated exertions on the maximum torque males and females could exert in different postures with four wrenches and four screwdrivers were investigated experimentally. Quantitative data were collected by conducting two independent sequential experiments. Circular grips for wrenches and triangular grips for screwdrivers maximised torque exertion capability. The peak torque declined with the duration of repeated exertions but stabilised after 180 s. Wrist orientation also had a significant influence on how much torque individuals could exert. A third experiment generated torque data for two additional body postures that were not included in previous works. From this investigation, correction factors were developed to generate peak torque exertion capability data of individuals with wrenches and screwdrivers for a variety of conditions dictated .by body posture, wrist orientation, duration of repeated exertions, and grip shape. The paper includes the basic torque exertion capability design data tables and the correction factors. 20.4.13 (112219)
Harma, M., Ilmarinen, J., and Knauth, P. Physical fitness and other individual factors relating to the shiftwork tolerance of women. Chronobiol Int, 1988, 5 . 4 , 4 1 7 - 4 2 4 , 28 refs. Maximal oxygen consumption (VO2 max), muscle strength (MS) and physical activity were compared with age, shiftwork experience, momingness, personality traits and social factors intervening in the shiftwork tolerance of 128 women. The subjects were nurses and nursing aids working irregular shifts in a hospital. Neuroticism was the most powerful negative factor connected to higher fatigue and various symptoms of the subjects. High VO 2 max and good MS were, on the other hand, the most important positive factors connected to lower fatigue and musculo-skeletal symptoms and better sleep quality of the subjects.
December 1989
The paper summarises three studies on wayfinding and the underlying spatio-cognitive skills of the visually impaired. The results suggest equivalent spatio-cognitive skills for all types of visual impairment, including the congenitally totally blind. A survey showed that public buildings are generally only accessible to a small proportion of blind visitors. It is argued that the key problem is one of access to information and that by designing adequate information systems, efficient wayfinding behaviour can be supported. By making buildings accessible to the blind population, new questions of safety and security emerge. Based on the above research, ideas for making buildings both accessible and safe are suggested° 20.4.15 (112237)
Knauth, P., Condon, R., Colquhoun, W.P., Plett, R., Sehmidt, K.H., and Rutenfranz, J. Alertness of watchkeeping personnel during long distance ship voyages. In: Vigilance: Methods, Models and Regulation, J.P. Leonard (Ed). Verlag Peter Lang, Frankfurt am Main, 1988, pp 9 1 - 9 8 , 22 refs. Four-hourly alertness ratings from 25 subjects on five ships were analysed. Individual subjects were studied over a period of between 3 and 13 days. The data showed circadian variation with the greatest impairment of alertness at 0400 h. Alertness improved from the beginning to the end of each watch during the first half of the day, and declined over each watch during the second half of the day, 20.4.16 (112265)
Meshkati, N., and Loewenthal, A. An eclectic and critical review of four primary mental workload assessment methods: A guide for developing a comprehensive model. In: Human Mental Workload, P.A. Hancock and N. Meshkati (Eds). North-Holland, Amsterdam, 1988, pp 2 5 1 - 2 6 7 , 85 refs. Four primary methods of mental workload assessment - i e, secondary task, subjective rating, performance