Ergonomics
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Two functionally distinct types of fixation, guiding fixations and look-ahead fixations, have been identified in naturalistic tasks based on their temporal relationship to the task execution. In car driving, steering through a curve is guided by fixations toward a region located 1-2 s in the future, but drivers also make fixations further along the road. We recorded drivers' eye movements while they drove an instrumented vehicle on curved rural roads and developed a method to quantify lead time and distance of look-ahead fixations. We also investigated the effect of cognitive load on look-ahead fixations. The look-ahead fixations appear to have a pattern which is connected to the sequential structure of a curve. This suggests that they have a role both in advance planning of the driving line and in the anticipation of oncoming vehicles. Cognitive load led to a shorter look-ahead lead time and distance. ⋯ We developed a method to quantify lead time and distance of look-ahead fixations in curve driving from on-road eye movement data. The results are relevant for driver modelling and development of anticipation training programmes for novice drivers.
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Two studies are reported which first observe, and then attempt to replicate, the cognitive demands of intensive care unit (ICU) activity whilst concurrently learning audible alarms. The first study, an observational study in an ICU ward, showed that the alarms are very frequent and co-occur with some activities more than others. The three most frequently observed activities observed in the ICU were drugs (calculation, preparation and administration), patient observation and talking. The cognitive demands of these activities were simulated in a second, laboratory-based experiment in which alarms were learned. The results showed that performance in the alarm task generally improved as participants were exposed to more repetitions of those alarms, but that performance decrements were observed in the secondary tasks, particularly when there were two or three of them. Some confusions between the alarms persisted to the end of the study despite prolonged exposure to the alarms, confusions which were likely caused by both acoustic and verbal labelling similarities. ⋯ The cognitive demands of working in an ICU were observed and simulated whilst alarms were learned. Alarms should generally avoid sharing similar rhythmic (and other) characteristics. The simulation task described here could be used for testing alarm learning without requiring a clinical environment.
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A total of 24 participants with non-specific chronic low back pain (NSCLBP) sat for 2 h while their seated posture and low back discomfort (LBD) were analysed. A total of 16 pain developers (PDs), whose LBD increased by at least two points on the numeric rating scale, repeated the procedure 1 week later, while receiving postural biofeedback. PDs were older (p = 0.018), more disabled (p = 0.021) and demonstrated greater postural variability (p < 0.001). The ramping up of LBD was reduced (p = 0.002) on retesting, when sitting posture was less end-range (p < 0.001), and less variable (p = 0.032). Seated LBD appears to be related with modifiable characteristics such as sitting behaviour. Among people with sitting-related NSCLBP, the ramping up of LBD was reduced by modifying their sitting behaviour according to their individual clinical presentation. The magnitude of change, while statistically significant, was small and no follow-up of participants was completed. Further research should examine integrating biofeedback into comprehensive biopsychosocial management strategies for NSCLBP. ⋯ The effect of real-time postural biofeedback on LBD was examined among people with LBP. Postural biofeedback matched to the individual clinical presentation significantly reduced LBD within a single session. Further research should examine the long-term effectiveness of postural biofeedback as an intervention for LBP.
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To examine the effects of firefighters' self-contained breathing apparatus' (SCBA) weight and its harness design on the physiological and subjective responses, eight male students performed treadmill exercise under four conditions: the 8 kg firefighter protective clothing (PC) (Control), the PC + an 11 kg SCBA with an old harness (Test A), the PC + a 6.4 kg SCBA with an old harness (Test B) and the PC + a 6.4 kg SCBA with a new harness (Test C), at ambient temperatures (T(a)) of 22°C and 32°C. Besides highlighting the fact that a heavy SCBA had a significant effect on the oxygen consumption and metabolic rate, this experiment also found that in a T(a) of 32°C, in particular, the combined effect of 4.7 kg lighter SCBA and new harness design could reduce metabolic rate and improved subjective muscle fatigue and thermal discomfort. ⋯ An effort to alleviate the physiological and subjective burden of firefighters by reducing the weight of SCBA and by using the new harness design has provided satisfactory results in reduced oxygen consumption and in improved subjective responses in a hot air environment.
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Comparative Study
A biomechanical and subjective assessment and comparison of three ambulance cot design configurations.
Effects of ambulance cot design features (handle design and leg folding mechanism) were evaluated. Experienced ambulance workers performed tasks simulating loading and unloading a cot to and from an ambulance, and a cot raising task. Muscle activity, ratings of perceived exertion, and performance style were significantly affected by cot condition (p < 0.05). ⋯ Providing handle options and automatic leg folding/unfolding operation can reduce cot operator's effort and physical strain. Practitioner Summary: Paramedics frequently incur musculoskeletal injuries associated with patient-handling tasks. A controlled experiment was conducted to assess effects of ambulance cot design features on physical stress of operators, as seen through muscle activity and operator's perceptions. Differences between cots were found, signalling that intentional design can reduce operator's physical stress.