Effects of the rate of computer-mediated speech on emotion-related subjective and physiological responses

In this paper, we describe the results of a psychophysiological study on user's judgements on, and physiological responses to, audio news, which were presented on computer with a fast and slow reading rate. Several effects of condition, age, gender, level of education and level of computer-user experience on the evaluation of the understandability, valence, arousal and interest of the news, as well as on electrodermal and facial muscle activity were found. For example, the fast news was judged as more arousing, but the slow news as more understandable. The younger subjects judged the fast news as more positive and interesting, whereas the opposite was true for older subjects. The results have several methodological and practical implications on presenting and studying speech information in computer systems, such as speech interfaces and news services, given the possibilities afforded by modern technology to present multimodal information effectively and adapt the information and/or interfaces to fit the characteristics of the user (e.g. age).     

Effects of the self-contained breathing apparatus and fire protective clothing on maximal oxygen uptake

To examine the effects of firefighting personal protective ensemble (PPE) and self-contained breathing apparatus (SCBA) on exercise performance, 12 males completed two randomly ordered, graded exercise treadmill tests (GXTPPE and GXTPT). Maximal oxygen consumption (VO2max) during GXTPPE was 17.3% lower than the GXTPT in regular exercise clothing (43.0 +/- 5.7 vs. 52.4 +/- 8.5 ml/kg per min, respectively). The lower VO2max during the PPE condition was significantly related (r = 0.81, p < 0.05) to attenuated peak ventilation (142.8 +/- 18.0 vs. 167.1 +/- 15.6 l/min), which was attributed to a significant reduction in tidal volume (2.6 +/- 10.4 vs. 3.2 +/- 0.4 l). Breathing frequency at peak exercise was unchanged (55 +/- 7 vs. 53 +/- 7 breaths/min). The results of this investigation demonstrate that PPE and the SCBA have a negative impact on VO2max. These factors must be considered when evaluating aerobic demands of fire suppression work and the fitness levels of firefighters.     

Effects of the self-contained breathing apparatus and fire protective clothing on maximal oxygen uptake

To examine the effects of firefighting personal protective ensemble (PPE) and self-contained breathing apparatus (SCBA) on exercise performance, 12 males completed two randomly ordered, graded exercise treadmill tests (GXT_PPE and GXT_PT). Maximal oxygen consumption (VO_2max) during GXT_PPE was 17.3% lower than the GXT_PT in regular exercise clothing (43.0 ± 5.7 vs. 52.4 ± 8.5 ml/kg per min, respectively). The lower VO_2max during the PPE condition was significantly related (r = 0.81, p < 0.05) to attenuated peak ventilation (142.8 ± 18.0 vs. 167.1 ± 15.6 l/min), which was attributed to a significant reduction in tidal volume (2.6 ± 10.4 vs. 3.2 ± 0.4 l). Breathing frequency at peak exercise was unchanged (55 ± 7 vs. 53 ± 7 breaths/min). The results of this investigation demonstrate that PPE and the SCBA have a negative impact on VO_2max. These factors must be considered when evaluating aerobic demands of fire suppression work and the fitness levels of firefighters.     

Physiological and subjective responses to breathing resistance of N95 filtering facepiece respirators in still-sitting and walking

The objective of this study was to assess the impact of breathing resistance on physiological and subjective responses to N95 filtering facepiece respirators (N95 FFRs) during still-sitting and walking. Fifteen subjects sat for 5 min and walked for 5 min while wearing 2 different models of N95 FFRs, 1 model of which was equipped with exhalation valves (N95 FFR/EV). The subjects were monitored by a modified monitoring garment for respiratory signals (RSP) and surface electromyography (sEMG). Subjects also were asked to complete subjective ratings of overall breathing resistance. The results of the physiological measurements in this study have shown that compared with no respirator, wearing N95 FFR had a direct effect on increasing respiratory amplitude, muscle activity and fatigue of abdominal, and fatigue of scalene; The use of N95 FFR/EV conferred limited physiological benefit over N95 FFR in walking; Compared with sitting still, walking significantly decreased respiratory amplitude, but increased respiratory rate, the muscle activity of sternomastoid, scalene, diaphragm and abdominal, the fatigue of scalene and intercostal. The subjective survey showed that wearing respirators and walking had a direct effect on improving the subjective overall breathing resistance. Significantly low to moderate correlation coefficients were shown between physiological values (respiratory amplitude, the muscle activity of diaphragm, the muscle activity and fatigue of scalene and abdominal), and the subjective breathing resistance. This is the first reported study that combines RSP, sEMG and subjective overall breathing resistance to evaluate breathing resistance on the use of N95 FFR in sitting still and walking. The physiological responses to breathing resistance of wearing a N95 FFR for 5 min in still-sitting and walking are relatively small and should generally be well tolerated by healthy persons.Relevance to industryThis paper's findings can be readily employed by respirator manufactures and administrations for evaluating the respiratory muscle function (activity, fatigue) and breathing parameters of wearing N95 FFRs. Observations of present study are in support of issuing new regulations to raise the limit for breathing resistance over short periods at low-moderate exertion tasks. Thus, the manufacturers could easily fulfill the requirements for collection efficiency by adding more filter media while still meeting the requirements for air resistance.     

The effects of a sloped ground surface on trunk kinematics and L5/S1 moment during lifting

There are many work environments that require workers to perform manual materials handling tasks on ground surfaces that are not perfectly flat (e.g. in agriculture, construction, and maritime workplaces). These sloped ground surfaces may have an impact on the lifting strategy/technique employed by the lifter, which may, in turn, alter the biomechanical loading of the spine. Describing the changes in kinematics and kinetics of the torso is the first step in assessing the impact of these changes and is the focus of the current research. Subjects' whole-body motions were recorded as they lifted a 10 kg box while standing on two inclined surfaces (facing an upward slope: 10° and 20°), two declined surfaces (facing a downward slope: ? 10° and ? 20°), and a flat surface (0°) using three lifting techniques (leg lift, back lift and freestyle lift). These data were then used in a two-dimensional, five-segment dynamic biomechanical model (top-down) to evaluate the effect of these slopes on the net moment about the L5/S1 joint. The results of this study showed an interesting interaction effect wherein the net L5/S1 moment was relatively insensitive to changes in slope angle under the back lift condition, but showed a significant effect during the leg lift and freestyle lifting conditions. The results show that under the freestyle lifting condition the peak L5/S1 moment was significantly higher for the inclined surfaces as compared to the flat surfaces (6.8% greater) or declined surfaces (10.0% greater). Subsequent component analysis revealed that both trunk flexion angle and angular trunk acceleration were driving this response. Collectively, the results of this study indicate that ground slope angle does influence the lifting kinematics and kinetics and therefore needs to be considered when evaluating risk of low back injury in these working conditions.     

Effects of surface roughness and interface wettability on nanoscale flow in a nanochannel

Non-equilibrium molecular dynamics simulations have been carried out to investigate the effect of surface roughness and interface wettability on the nanorheology and slip boundary condition of simple fluids in a nanochannel of several atomic diameters width. The solid surfaces decorated with periodic nanostrips are considered as the rough surface in this study. The simulation results showed that the interface wettability and the surface roughness are important in determining the nanorheology of the nanochannel and fluid slip at solid–fluid interface. It is observed that the presence of surface roughness always suppresses the fluid slip for hydrophilic and hydrophobic surface nanochannels. For fluids over smooth and hydrophobic surfaces, the snapshots of fluid molecules show that an air gap or nanobubble exists at the fluid–solid interface, resulting in the apparent slip velocity. For a given surface with fixed interface wettability, the fluid velocities increase by increasing the driving force, while the driving force has no significant influence on the density structure of fluid molecules. The fluid slip and the flow rate are measured for hydrophilic and hydrophobic nanochannels. The flow rates in rough surface nanochannels are smaller than those of smooth surface walls due to the increase of drag resistance at the solid–fluid interface. The dependence between fluid slip and flow rate showed that the slip length increases approximately linearly with the flow rate for both the hydrophobic and hydrophilic surface nanochannels.     

Effects of slanted ergonomic mice on task performance and subjective responses

The biomechanical benefits (e.g., muscular activity) of slanted ergonomic mice have been comprehensively identified; however, their effects on task performance and subjective responses have not been fully investigated. The present study examined the effects of two slanted mice (slant angle = 30° and 50°) in comparison with a conventional mouse (slant angle = 0°) in terms of task performance (task completion time and error rate) and subjective responses (perceived discomfort score and overall satisfaction score). Experimental results showed that all of the task and subjective measures worsened as the slant angle of the target mice increases. For example, the task completion time (unit: ms) and overall satisfaction score (unit: point) of the 30° slanted mouse (time = 0.71, satisfaction = −0.09) and 50° slanted mouse (time = 0.73, satisfaction = −0.79) significantly deteriorated than the conventional mouse (time = 0.65, satisfaction = 1.21). The slanted mice seem to compromise biomechanical benefits with task performance and subjective responses.     

The influence of flywheel weight and pedalling frequency on the biomechanics and physiological responses to bicycle exercise†

The physiological, subjective and biomechanical effects of altering flywheel weight and pedalling rate on a Quinton Model 870 bicycle ergometer were studied. Steel plates were added to the flywheel to increase its weight to 35·9 kg with a moment of inertia of 1·65 kg m². A 1·5 kg spoked wheel with a moment of inertia of 0·1 kg m² was used as the light flywheel. Eight subjects pedalled on two separate occasions for 6 min at 40, 50, 60, 70, 80 and 90 r.p.m. with workload levels representing 30 and 60% of their [Vdot]O₂max with each flywheel. Force plate pedals were used to measure the total resultant force on the pedals (F_R ) and the component perpendicular to the crank arm (F_T). A force effectiveness index (FEI) was denned as the average of F_T/F_R over a crank cycle. The result showed no statistically significant change (p<0·05) in [Vdot]O₂, heart rate and rating of perceived exertion of the FEI as a function of flywheel weight except for the [Vdot]O₂ at 50 r.p.m. for the light workload. As the r.p.m. increased from 40 to 90 r.p.m., the FEI decreased from 0·5 to 0·35 with the heavy load and from 0·36 to 0·22 with the light load. Measured physiological, subjective and biomechanical indices did not change significantly with flywheel weight. Increasing the pedalling rate caused a significantly less effective application of forces to the crank arm with only a small change in [Vdot]O₂.     

Effect of safety shoes type,lifting frequency,and ambient temperature on subject's MAWL and physiological responses

ObjectiveThe purpose of this paper is to evaluate the lifting capabilities of individuals while wearing safety shoes in a hot environment and to investigate the behavior of the physiological responses induced by the lifting process associated with those variables.MethodsIn order to achieve the objectives of this research, two sequential studies were conducted. The first part was an acclimatization and training program followed by a psychophysical experiment. Seven male workers participated in this experiment from the university. A three-way repeated measures design, with three independent variables and seven response variables, was utilized in this study. The independent variables studied in the psychophysical experiment were: 1) environmental temperature (20 and 30 °C WBGT), 2) lifting frequency (1 and 5 lifts/min), and 3) safety shoes (light-duty, medium-duty and heavy-duty). The response variables for this experiment were: 1) maximum acceptable weight of lift (MAWL), 2) heart rate, 3) aural-canal temperature, 4) muscle electromyography (EMG) of four muscle groups (biceps brachii, anterior deltoid, trapezius, and erector spinae), 5) rating of perceived exertion, 6) rating of thermal sensation and7) safety shoes discomfort rating.ResultsThe psychophysical experiment results showed that the weights selected by participants at higher levels of the independent variables were significantly less than those selected at lower levels of the independent variables. Some of the interaction effects were also significant.ConclusionThis study found evidence that – in addition to lifting frequency, which is well reported in the literature – heat stress increases the workload intensity in manual lifting tasks influencing the psychophysical selection of MAWL and the physiological responses of the human body represented in aural-canal temperature, heart rate and muscular activities. The study findings demonstrated the necessity of accounting for work environmental temperature and type of worn safety shoes, which is a safety requirement by most employers, when calculating the recommended weight limits.Practitioner summaryMost of the manual materials handling studies had investigated worker's capacity to perform lifting tasks in different environmental conditions not considering the effect of wearing safety shoes. This research fills the gap by presenting safety guidelines regarding lifting tasks in a hot environment while wearing safety shoes.     

The effects of container design and stair climbing on maximal acceptable lift weight, wrist posture, psychophysical, and physiological responses in wafer-handling tasks

Despite the high level of automation in semiconductor manufacturing processes, many manual operations are still involved in the workplace. Due to inadequate human–machine interface design, stairs are frequently used to help operators perform wafer-handling tasks. This study was designed to evaluate the effects of climbing stairs and carrying wafer containers (pods) on psychophysical responses (maximal acceptable weight of lift—MAWL, and ratings of perceived exertion—RPE), physiological responses (oxygen consumption—VO₂, and heart rate—HR), and wrist posture (ulnar and radial deviations). Each of 12 subjects (six males and six females) performed six sessions (3 climbing stairs×2 pods types). The results indicate that climbing stairs had a significant influence on MAWL and VO₂ (p<0.01). The type of pod effect on wrist posture was significant (p<0.01). Gender effect differences on MAWL, VO₂ and wrist posture were also significant (p<0.05). Job design implications are discussed.     

Effects of age and its interaction with task parameters on lifting biomechanics

This study investigated the age-related differences in lifting biomechanics. Eleven younger and 12 older participants were instructed to perform symmetric lifting tasks defined by different combinations of destination heights and load magnitudes. Lifting biomechanics was assessed. It was found that the trunk flexion in the starting posture was 32% lower and the peak trunk extension velocity was 46% lower in older participants compared with those in younger ones, indicating that older adults tended to use safer lifting strategies than did younger adults. Based on these findings, we recommend that physical exercise programmes may be a more effective ergonomic intervention for reducing the risks of low back pain (LBP) in lifting among older workers, compared with instructions of safe lifting strategies. As for younger workers, instructions of safe lifting strategies would be effective in LBP risk reduction.     

Method to assist the building and expression of subjective concepts and its application to design problems

The paper discusses how computers can assist human creativity. A support system has been built and applied to the domain of automobile design. The system uses multidimensional data and statistical methods, and configures a space for inspiring the users' design activity. In the first step, it assists them in forming individual design concepts. In the second step, it assists them in deciding their target design concepts. It has been confirmed that it works effectively through experiments. Some of the open questions on creativity support systems are also discussed.     

Effects of shear rate and small periodic corrugation on the slip velocity in microscopic domain

We obtain analytically the slip velocity (up to the second order) of shear-thinning fluids inside the periodically corrugated microtube by using the verified fluid model and boundary perturbation method. Our results show that, even the slip length being zero, there is a slip velocity which is proportional to the small amplitude of periodic corrugation, the (referenced) shear rate, the applied forcing, and the orientation or the angle. Our results could be applied to the flow control in microfluidics as well as biofluidics.     

Effects of wearing aircrew protective clothing on physiological and cognitive responses under various ambient conditions

Heat stress can be a significant problem for pilots wearing protective clothing during flights, because they provide extra insulation which prevents evaporative heat loss. Heat stress can influence human cognitive activity, which might be critical in the flying situation, requiring efficient and error-free performance. This study investigated the effect of wearing protective clothing under various ambient conditions on physiological and cognitive performance. On several occasions, eight subjects were exposed for 3 h to three different environmental conditions; 0°C at 80% RH, 23°C at 63% RH and 40°C at 19% RH. The subjects were equipped with thermistors, dressed as they normally do for flights (including helmet, two layers of underwear and an uninsulated survival suit). During three separate exposures the subjects carried out two cognitive performance tests (Vigilance test and DG test). Performance was scored as correct, incorrect, missed reaction and reaction time. Skin temperature, deep body temperature, heart rate, oxygen consumption, temperature and humidity inside the clothing, sweat loss, subjective sensation of temperature and thermal comfort were measured. Rises in rectal temperature, skin temperature, heart rate and body water loss indicated a high level of heat stress in the 40°C ambient temperature condition in comparison with 0°C and 23°C. Performance of the DG test was unaffected by ambient temperature. However, the number of incorrect reactions in the Vigilance test was significantly higher at 40°C than at 23°C (p = 0.006) or 0°C (p = 0.03). The effect on Vigilance performance correlated with changes in deep-body temperature, and this is in accordance with earlier studies that have demonstrated that cognitive performance is virtually unaffected unless environmental conditions are sufficient to change deep body temperature.     

Rapid Communication Effects of posture,weight and frequency on trunk muscular activity and fatigue during repetitive lifting tasks

Abstract

We examined the effects of posture, weight and frequency on trunk muscular activity and fatigue during repetitive dynamic lifting. Electromyographic (EMG) signals from eight primary trunk muscles were collected during 120 min for four different task conditions. The patterns of muscle recruitment and the levels of relative activation were analysed using the normalized EMG data. Median power frequency (MPF) shift patterns were analysed to examine muscular fatigue. The muscles in the dorsal part of the trunk were activated at the symmetric posture, while the muscles on the contralateral side to the workload were more strongly activated at the asymmetric posture. Decreasing trends of MPFs were found in some active muscles, and they were more pronounced for the asymmetric posture than for the symmetric posture. It was also seen that the muscles became fatigued faster for the light load-high frequency task than for the heavy load-low frequency task.     

Effects of display method,text display rate and observation angle on comprehension performance and subjective preferences for reading Chinese on an LED display

This study examined the effects of display method, text display rate, and observation angle on comprehension performance and subjective preferences for Chinese characters presented on an LED display. The factors and levels studied were as follows: four text display methods (rapid serial visual presentation ‘RSVP’, leading, paged view scrolling, and continuous scrolling), three text display rates (160 characters per min ‘cpm’, 240 cpm, and 320 cpm), and seven observation angles (−75°, −60°, −30°, 0°, 30°, 60°, and 75°). The results indicated that a display rate of 160 cpm was in general superior to 240 and 320 cpm for comprehension scores and subjective evaluations. The effects of display method and observation angle were found to be non significant. However, there was a significant interaction between display method and display rate. The results of this study were used to make ergonomics recommendations applicable to LED displays for determining optimum dynamic text display methods for Chinese characters.     

Effects of setting up of humidifiers on thermal conditions and subjective responses of patients and staff in a hospital during winter

The purpose of this survey was to measure the thermal environment in a hospital during winter, and to investigate the subjective responses of patients and staff via a questionnaire. The air temperature and humidity in the sickrooms and nurse stations were measured for 3 months during winter. After 2 months, we introduced humidifiers into about half of the rooms and nurse stations as a method of improving the environment, and evaluated the effects of the installed humidifiers on the thermal conditions. In all, 36 patients and 45 staff members were asked once a week about subjective symptoms (dry and itchy skin, thirst, etc.). Before setting up the humidifiers, the existence of a low-humidity environment in the hospital during winter was confirmed, with the levels of relative humidity and humidity ratio reaching under 50% and 5g/kg DA, respectively, which is known to promote the spread of influenza viruses. However, the introduction of the humidifiers increased the relative humidity in sickrooms from 32.8% to 43.9% on average, and the air humidity in sickrooms thus almost reached the optimum range suggested by the Hospital Engineering Association of Japan (HEAJ). Additionally, complaints of thermal discomfort and dryness of air decreased among the staff, though not among the patients, after the humidifiers were installed. These results suggest that introducing humidifiers into a hospital during winter is an effective method of improving the low-humidity environment and relieving the discomfort of staff members.     

The effect of reducing the number of EMG channel inputs on loading and stiffness estimates from an EMG-driven model of the spine

Electromyography (EMG)-driven models of the spine routinely require between ten and 14 EMG channels to estimate joint load and stiffness variables. This study was designed to determine the sensitivity of common EMG-driven model outputs to the removal of individual EMG channels, and to test two adapted models driven from eight channels. A total of 11 male participants performed a variety of static exertions designed to resist either an applied trunk flexion or right side trunk lateral bend moment. In this study, 14 channels of EMG were recorded and used to drive a biomechanical model of the spine to predict L4-L5 joint load and stiffness values. The model was subsequently re-run after the removal of individual pairs of bilateral EMG channels, and again with eight-channel models in which the rectus abdominus, latissimus dorsi and multifidus EMG-channels were eliminated. Results showed that the eight-channel model provided estimates for the majority of output variables that did not differ substantially from the 14-channel model, except in instances in which muscle force output was ramped to resist flexion moments. Estimates of the output variables were, in general, improved when multifidus fascicles were re-added to the model and driven from the lumbar erector spinae EMG sites.