Effect of an on-body ergonomic aid on oxygen consumption during a repetitive lifting task

The purpose of this study was to determine if an on-body personal lift assistive device (PLAD)¹ affected oxygen consumption during a continuous lifting task and to investigate if any effect could be explained by differences in muscle activity or lifting technique. The PLAD, worn like a back-pack, contains a spring-cable mechanism that assists the back musculature during lifting, lowering, and forward bending tasks. Males (n = 15) lifted and lowered a box loaded to 10% of their maximum back strength at 6 times/minute for 15-minutes using a free-style technique under two conditions: wearing and not wearing the PLAD. Oxygen consumption was collected continuously for the first condition; then the participants rested until their heart rates returned to resting levels before repeating the protocol for the second condition. Knee flexion was monitored using Liberty sensors at the hip, knee, and ankle. EMG of the thoracic and lumbar erector spinae (TES, LES), biceps femoris, rectus femoris and gluteus maximus were gathered using a Bortec AMT-8 channel system. VO2 measures were averaged across the duration (15 min) for each condition. Results showed no differences between oxygen consumption during the PLAD and no PLAD conditions. When wearing the PLAD, the TES demonstrated an 8.4% EMG reduction when lowering the box while the biceps femoris showed a 14% reduction while lifting the box. Knee angles, used as a proxy for stoop or squat lifts, were highly variable for both conditions. In conclusion, the PLAD had no effect on oxygen consumption and, therefore, neither workers nor employers should increase the tasks demands when wearing this ergonomic aid.     

Evaluation of lifestyle risk factors and job status associated with back injuries among employees at a mid-western university

For decades the literature has shown an association between work-related risk factors and back injuries among employees. However, only recently, there is a growing body of literature that suggests lifestyle risk factors may also be associated with back injuries. The purpose of this research was to determine if selected lifestyle risk factors are associated with a greater risk of back injuries. Further, there may be an association between job status and incident reporting, lost workdays cases and workers' compensation (WC) paid for back injuries among university employees. Aggregate data from a Health Risk Assessment (HRA) questionnaire were used to analyze 6053 university employees for lifestyle risk factors associated with back injuries. Of the total sample, 57% (n = 3471) were female; 46% (n = 2778) worked as clerical or service staff; and the mean age was 45 years. Pearson chi-square (χ²) analyses indicate that job status (χ² = 307.07, df = 4, p < .001) and gender (χ² = 40.14, df = 2, p < .001) were associated with high risk back score. An ordinal regression analysis predicted that participants who exercised vigorously for at least 20 min, 3 or more days per week, or 3 or more days per week of combined vigorous exercise and moderate-intensity physical activity are almost 30 times less likely to have a high back risk score compared to participants who do not exercise vigorously or participate in less than 3 days per week of moderate-intensity physical activity (OR = 29.68, 95% CI = 25-35.25, p < .001). Participants who have a low risk score for BMI are three times less likely (OR = 3.20, 95% CI = 2.74-3.75, p < .001) to have a high back risk score when compared to participants who have a high risk score for BMI. A regression tree predicted high back risk scores were participants who: (1) receive an adequate amount of physical activity or vigorous exercise and is a male service or clerical staff; (2) do not receive an adequate amount of physical activity or vigorous exercise, and is not overweight; or (3) who do not receive an adequate amount of physical activity or vigorous exercise, and is overweight. Six years of Occupational Safety and Health Administration (OSHA) 300 logs and WC claims data paid for back injuries supported the finding that clerical or service staff had the greatest risk of back injuries. Based on the results of this study, there appears to be an association between lifestyle risk factors, job status and back injuries among university employees. We believe our evaluation approach may be used to study other work populations to verify the outcomes observed in this study.     

Ergonomic evaluation of masons laying concrete masonry units and autoclaved aerated concrete

Masons working with concrete masonry unit block have high rates of work-related musculoskeletal disorders to the low back and shoulders associated with repetitively lifting and buttering heavy block. A new material, autoclaved aerated concrete, may reduce the risk of shoulder and back injury but, ergonomic evaluation is needed. This study evaluated shoulder exposure parameters, low back stress, and worker perceptions in two groups of journey level masons, one using CMU and the other using AAC block. Results indicate that for the left arm AAC masons spent significantly more time than CMU masons in static (38.2% versus 31.1%, respectively), and less time in slow motions (48.2% versus 52.2%, respectively) and faster motions (13.6% versus 16.7%, respectively) (p < 0.05). CMU masons had significantly greater shoulder and low back pain (p = 0.009) and they held block significantly longer than AAC masons (p < 0.001). Low back compressive forces were high for both materials. Masons handling AAC demonstrated less left upper extremity stress but both materials were estimated to be hazardous to the low back.     

Paramedics on the job: Dynamic trunk motion assessment at the workplace

Many paramedics' work accidents are related to physical aspects of the job, and the most affected body part is the low back. This study documents the trunk motion exposure of paramedics on the job. Nine paramedics were observed over 12 shifts (120 h). Trunk postures were recorded with the computer-assisted CUELA measurement system worn on the back like a knapsack. Average duration of an emergency call was 23.5 min. Sagittal trunk flexion of >40° and twisting rotation of >24° were observed in 21% and 17% of time-sampled postures. Medical care on the scene (44% of total time) involved prolonged flexed and twisted postures (∼10 s). The highest extreme sagittal trunk flexion (63°) and twisting rotation (40°) were observed during lifting activities, which lasted 2% of the total time. Paramedics adopted trunk motions that may significantly increase the risk of low back disorders during medical care and patient-handling activities.     

Assessment of engineering controls designed for handling unstable loads: An electromyography assessment

Low back injury due to manual lifting is historically prevalent in labor intensive industries. Improving risk management options is necessary to reduce the risk of low back injury. Workers lifting unstable loads are at greater risk of back injury compared to workers lifting stable loads. This study focused on the effect of engineering controls on trunk muscle activity. Engineering controls were designed to control the instability of a liquid load. Thirty-nine healthy subjects manually lifted asymmetrically in the transverse direction stable loads, unstable loads, and unstable loads with engineering controls. Trunk and load kinematic and trunk muscle electromyography data were collected during lifting. Unstable loads with engineering controls significantly (p < 0.001) reduced trunk muscle activity compared to unstable loads. Engineering controls should be implemented to reduce the risk of injury to workers handling unstable liquid loads.Relevance to industryManually handling containers filled with liquids is necessary in many industrial workplaces. Risk management solutions for low back injury due to manual lifting of such loads should focus on reducing muscular demand. This study demonstrates that engineering controls designed to increase the stability of a liquid load reduced muscular demand.     

The personal lift-assist device and lifting technique: a principal component analysis

The personal lift-assist device (PLAD) is a non-motorised, on-body device that acts as an external force generator using the concept of stored elastic energy. In this study, the effect of the PLAD on the lifting kinematics of male and female lifters was investigated using principal component analysis. Joint kinematic data of 15 males and 15 females were collected using an opto-electronic system during a freestyle, symmetrical-lifting protocol with and without wearing the PLAD. Of the 31 Principal Components (PCs) retained in the models, eight scores were significantly different between the PLAD and no-PLAD conditions. There were no main effects for gender and no significant interactions. Results indicated that the PLAD similarly affected the lifting kinematics of males and females; demonstrating significantly less lumbar and thoracic flexion and significantly greater hip and ankle flexion when wearing the PLAD. These findings add to the body of work that suggest the PLAD may be a safe and effective ergonomic aid.

Statement of Relevance: The PLAD is an ergonomic aid that has been shown to be effective at reducing low back demands during manual materials handling tasks. This body of work establishes that the PLAD encourages safe lifting practices without adversely affecting lifting technique.     

Effect of prescribed sleep surfaces on back pain and sleep quality in patients diagnosed with low back and shoulder pain

The purpose of this study was to assess sleep quality and comfort of participants diagnosed with low back pain and stiffness following sleep on individually prescribed mattresses based on dominant sleeping positions. Subjects consisted of 27 patients (females, n = 14; males, n = 13; age 44.8 yrs ± SD 14.6, weight 174 lb. ±SD 39.6, height 68.3 in. ± SD 3.7) referred by chiropractic physicians for the study. For the baseline (pretest) data subjects recorded back and shoulder discomfort, sleep quality and comfort by visual analog scales (VAS) for 21 days while sleeping in their own beds. Subsequently, participants’ beds were replaced by medium-firm mattresses specifically layered with foam and latex based on the participants’ reported prominent sleeping position and they again rated their sleep comfort and quality daily for the following 12 weeks. Analysis yielded significant differences between pre- and post means for all variables and for back pain, we found significant (p < 0.01) differences between the first posttest mean and weeks 4 and weeks 8-12, thus indicating progressive improvement in both back pain and stiffness while sleeping on the new mattresses. Additionally, the number of days per week of experiencing poor sleep and physical discomfort decreased significantly. It was concluded that sleep surfaces are related to sleep discomfort and that is indeed possible to reduce pain and discomfort and to increase sleep quality in those with chronic back pain by replacing mattresses based on sleeping position.     

Frequency of the sit to stand task: An observational study of free-living adults

The sit to stand movement is a key determinant of functional independence. Knowledge of the frequency with which the sit to stand movement is performed throughout the day could inform workplace ergonomics, but has rarely been examined.Healthy adults (n = 140) were recruited from the general population. Free-living activity for each participant was reported using an activity monitor. On average, participants performed 60 (±22) sit to stand movements each day. Participants in indoor sedentary occupations performed significantly more sit to stand movements per day than participants in outdoor active occupations (66 vs. 54; n = 102; p = 0.003). Participants (n = 33) performed significantly more sit to stand movements on working days than on non-working days (65 vs. 55; p = 0.018).This analysis provides contemporary data for sit to stand frequency in a predominantly working population, and demonstrates that work and employment have a significant effect on that frequency.     

Development of virtual reality proprioceptive rehabilitation system for stroke patients

In this study, the virtual reality (VR) proprioception rehabilitation system was developed for stroke patients to use proprioception feedback in upper limb rehabilitation by blocking visual feedback. To evaluate its therapeutic effect, 10 stroke patients (onset > 3 month) trained proprioception feedback rehabilitation for one week and visual feedback rehabilitation for another week in random order. Proprioception functions were checked before, a week after, and at the end of training. The results show the click count, error distance and total error distance among proprioception evaluation factors were significantly reduced after proprioception feedback training compared to visual feedback training (respectively, p = 0.005, p = 0.001, and p = 0.007). In addition, subjects were significantly improved in conventional behavioral tests after training. In conclusion, we showed the effectiveness and possible use of the VR to recover the proprioception of stroke patients.     

Ergonomic risk factors for the wrists of hairdressers

This study utilized a portable data logger to measure the wrist angles and forearm flexor and extensor electromyography (EMG) of 21 hairstylists. The hairstylists were divided into two groups, one with 11 barbers (9 males and 2 females) specializing in men's hairdressing, and one with 10 hairdressers (2 males and 8 females) specializing in women's hairdressing. The standard haircut task was divided into three subtasks: hair cutting, washing and blow-drying. The mechanical exposures of the overall task and subtasks were quantified to compare how subtasks, occupational groups, and gender groups differ. Experimental results show that the average time to finish a woman's haircut (51.4 min) is significantly longer than that for a man's haircut (35.6 min) (p < 0.005). Female hairstylists had significantly greater EMG activity than male hairstylists did (p < 0.001). The non-dominant hands of hairdressers have significantly higher overall wrist velocity than those of barbers (p < 0.005). Analytical results suggest that the relatively higher force exertion and wrist velocity of female hairstylists combined with prolonged exposure may account for the higher rate of hand/wrist pain in female hairdressers than in male barbers.     

The effects of clinical information presentation on physicians' and nurses' decision-making in ICUs

This research evaluated physicians' agreement about patients' diagnoses and nurses' ability to detect patient change using traditional charts (TC) and a work domain analysis-based paper prototype (PP) and also sought to determine whether differences persisted when the PP was represented as an electronic prototype (EP). Nurses' change detection improved using the PP and EP compared to TC (PP vs TC, t_(df=6) = 1.94, p < 0.03; EP vs TC, t_(df=6) = 3.14, p < 0.01) and detection was better using the EP compared with the PP (t_(df=6) = 5.96, p < 0.001). Physicians were more likely to agree about failed physiological systems using the EP compared with the PP (t_(df=10) = 3.14, p < 0.01), but agreement about patient diagnoses was higher using the PP compared with the EP (t_(df=10) = 2.23; p < 0.02). These results are attributed to information grouping around physiological functions and the direct association of cause-and-effect relations in clinical information design.     

Gas sensing properties of p-type hollow NiO hemispheres prepared by polymeric colloidal templating method

This work presents a simple and versatile route to produce macroporous p-type metal oxide thin films. Two-dimensional arrays of p-type NiO films with a hollow hemisphere structure were fabricated by colloidal templating and RF-sputtering followed by a subsequent heat treatment. The diameter and shell thickness of the NiO hemisphere were 800 nm and 20 nm, respectively. X-ray diffraction and high-resolution transmission electron microscopy analysis indicate that the pure NiO phase with grain size of 10 nm was obtained at calcination temperatures that exceeded 450 °C. Close-packed arrays of hollow NiO hemispheres were found to exhibit p-type gas sensing properties against (CO, H₂, C₃H₈, CH₄, NO₂, and C₂H₅OH), leading to significantly enhanced responses to C₂H₅OH (R_gas/R_air = 5.0 at 200 ppm).     

Sleep in a live-in mining operation: The influence of start times and restricted non-work activities

The amount of sleep obtained between shifts is influenced by numerous factors including the length of work and rest periods, the timing of the rest period relative to the endogenous circadian cycle and personal choices about the use of non-work time. The current study utilised a real-world live-in mining environment to examine the amount of sleep obtained when access to normal domestic, family and social activities was restricted. Participants were 29 mining operators (26 male, average age 37.4 ± 6.8 years) who recorded sleep, work and fatigue information and wore an activity monitor for a cycle of seven day shifts and seven night shifts (both 12 h) followed by either seven or fourteen days off. During the two weeks of work participants lived on-site. Total sleep time was significantly less (p < 0.01) while on-site on both day (6.1 ± 1.0 h) and night shifts (5.7 ± 1.5 h) than days off (7.4 ± 1.4 h). Further, night shift sleep was significantly shorter than day-shift sleep (p < 0.01). Assessment of subjective fatigue ratings showed that the sleep associated with both days off and night shifts had a greater recovery value than sleep associated with day shifts (p < 0.01). While on-site, participants obtained only 6 h of sleep indicating that the absence of competing domestic, family and social activities did not convert to more sleep. Factors including shift start times and circadian influences appear to have been more important.     

Absorption,dissociation, locus of control and presence in virtual reality

The present study aimed to explore the relationship between a number of psychological variables and a reported sense of presence in immersive virtual reality (IVR). It was hypothesised that participants’ scores on measures of absorption, dissociation, and external locus of control would be positively and significantly correlated with a measure of their sense of presence in IVR. A total of 64 people took part. Significant correlations were found between presence and dissociation (r = 0.403, p < 0.01), and presence and locus of control (r = 0.268, p < 0.05). However, the correlation between presence and absorption was not significant (r = −0.037, p = 0.386). The findings reported here suggest a complex interrelationship of psychological variables in relation to presence in IVR that warrants further research.     

Computer-related posture and discomfort in primary school children: The effects of a school-based ergonomic intervention

This study investigated the effect of a school-based ergonomic intervention on childrens’ posture and discomfort while using computers using a pre/post test study design. The sample comprised 23 children age 9 and 10 years. Posture was assessed with Rapid Upper Limb Assessment (RULA) and a workstation assessment was completed using a Visual Display Unit (VDU) checklist. Self reported discomfort was also recorded at the beginning and end of the computer class. Following an ergonomic intervention that included education of the children and workstation changes, the outcome measures were repeated. There was a positive response to the intervention with significant changes between the pre-intervention and post-intervention scores for posture (p = 0.00) and workstation (p = 0.00). The change in discomfort scores from beginning to end of the computer class between the pre-intervention class and the post-intervention class was also significant (p = 0.00). The study highlights the need for continuing concern about the physical effects of children’s computer use and the implications of school-based interventions.     

The effects of video on cognitive load and social presence in multimedia-learning

Two studies examined the use of video in multimedia learning environments. In Study 1, participants (N = 26) viewed one of two versions of a computer-based multimedia presentation: video, which included a video of a lecture with synchronized slides, or no video, which included the slides but only an audio narration of the lecture. Learning, cognitive load and social presence were assessed, but a significant difference was found only for cognitive load, with video experiencing greater cognitive load, t (24) = 2.45, p < .05. In Study 2, students (N = 25) were randomly assigned to either video or no video condition. Background knowledge and visual/verbal learning preference were assessed before viewing the presentation, and learning, cognitive load, and social presence were assessed after viewing. No significant differences were found for learning or social presence. However, a significant visual/verbal learning preference by condition interaction was found for cognitive load, F (1,21) = 4.51, p < .05: low visual-preference students experienced greater cognitive load in the video condition, while high visual-preference students experienced greater cognitive load in the no video condition.     

Effects of soil moisture and water depth on ERS SAR backscatter measurements from an Alaskan wetland complex

We conducted a preliminary investigation of the response of ERS C-band SAR backscatter to variations in soil moisture and surface inundation in wetlands of interior Alaska. Data were collected from 5 wetlands over a three-week period in 2007. Results showed a positive correlation between backscatter and soil moisture in sites dominated by herbaceous vegetation cover (r = 0.74, p < 0.04). ERS SAR backscatter was negatively correlated to water depth in all open (non-forested) wetlands when water table levels were more than 6 cm above the wetland surface (r = − 0.82, p < 0.001). There was no relationship between backscatter and soil moisture in the forested (black spruce-dominated) wetland site. Our preliminary results show that ERS SAR data can be used to monitor variations in hydrologic conditions in high northern latitude wetlands (including peatlands), particularly sites with sparse tree cover.     

Testing the potential of multi-spectral remote sensing for retrospectively estimating fire severity in African Savannahs

The remote sensing of fire severity is a noted goal in studies of forest and grassland wildfires. Experiments were conducted to discover and evaluate potential relationships between the characteristics of African savannah fires and post-fire surface spectral reflectance in the visible to shortwave infrared spectral region. Nine instrumented experimental fires were conducted in semi-arid woodland savannah of Chobe National Park (Botswana), where fire temperature (T_max) and duration (dt) were recorded using thermocouples positioned at different heights and locations. These variables, along with measures of fireline intensity (FLI), integrated temperature with time (T_sum) and biomass (and carbon/nitrogen) volatilised were compared to post-fire surface spectral reflectance. Statistically significant relationships were observed between (i) the fireline intensity and total nitrogen volatilised (r² = 0.54, n = 36, p < 0.001), (ii) integrated temperature (T_sum−μ) and total biomass combusted (r² = 0.72, n = 32, p < 0.001), and (iii) fire duration as measured at the top-of-grass sward thermocouple (dt_T) and total biomass combusted (r² = 0.74, n = 34, p < 0.001) and total nitrogen volatilised (r² = 0.73, n = 34, p < 0.001). The post-fire surface spectral reflectance was found to be related to dt and T_sum via a quadratic relationship that varied with wavelength. The use of visible and shortwave infrared band ratios produced statistically significant linear relationships with fire duration as measured by the top thermocouple (dt_T) (r² = 0.76, n = 34, p < 0.001) and the mean of T_sum (r² = 0.82, n = 34, p < 0.001). The results identify fire duration as a versatile measure that relates directly to the fire severity, and also illustrate the potential of spectrally-based fire severity measures. However, the results also point to difficulties when applying such spectrally-based techniques to Earth Observation satellite imagery, due to the small-scale variability noted on the ground. Results also indicate the potential for surface spectral reflectance to increase following higher severity fires, due to the laying down of high albedo white mineral ash. Most current techniques for mapping burned area rely on the general assumption that surface albedo decreases following a fire, and so if the image spatial resolution was high enough such methods may fail. Determination of the effect of spatial resolution on a sensor's ability to detect white ash was investigated using a validated optical mixture modelling approach. The most appropriate mixing model to use (linear or non-linear) was assessed using laboratory experiments. A linear mixing model was shown most appropriate, with results suggesting that sensors having spatial resolutions significantly higher than those of Landsat ETM+ will be required if patches of white ash are to be used to provide EO-derived information on the spatial variation of fire severity.     

On the relationship between training sample size and data dimensionality: Monte Carlo analysis of broadband multi-temporal classification

The number of training samples per class (n) required for accurate Maximum Likelihood (ML) classification is known to be affected by the number of bands (p) in the input image. However, the general rule which defines that n should be 10p to 30p is often enforced universally in remote sensing without questioning its relevance to the complexity of the specific discrimination problem. Furthermore, identifying this many training samples is often problematic when many classes and/or many bands are used. It is important, then, to test how this generally accepted rule matches common remote sensing discrimination problems because it could be unnecessarily restrictive for many applications. This study was primarily conducted in order to test whether the general rule defining the relationship between n and p was well-suited for ML classification of a relatively simple remote sensing-based discrimination problem. To summarise the mean response of n-to-p for our study site, a Monte Carlo procedure was used to randomly stack various numbers of bands into thousands of separate image combinations that were then classified using an ML algorithm. The bands were randomly selected from a 119-band Enhanced Thematic Mapper-plus (ETM+) dataset comprised of 17 images acquired during the 2001-2002 southern hemisphere summer agricultural growing season over an irrigation area in south-eastern Australia. Results showed that the number of training samples needed for accurate ML classification was much lower than the current widely accepted rule. Due to the asymptotic nature of the relationship, we found that 95% of the accuracy attained using n = 30p samples could be achieved by using approximately 2p to 4p samples, or ≤ 1 / 7th the currently recommended value of n. Our findings show that the number of training samples needed for a simple discrimination problem is much less than that defined by the general rule and therefore the rule should not be universally enforced; the number of training samples needed should also be determined by considering the complexity of the discrimination problem.     

Oriented growth of A2Te3 (A = Sb, Bi) films and their devices with enhanced thermoelectric performance

Oriented thermoelectric (TE) p-Sb₂Te₃ and n-Bi₂Te₃ thin films with special nanostructures have been synthesized by a simple vacuum thermal evaporation technique. The composition and microstructure of the films were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM), presenting a well preferential crystal growth with dense slender columnar grains grown perpendicular to the substrate, and energy dispersive X-ray spectrum (EDX) indicating the compositions distribution in the films. The electric transport properties, i.e., conductivity and Seebeck coefficient, and the thermal transportation of the oriented films show optimized properties. Prototype devices were built up by p and n elements in series and parallel circuits. The largest output power and cooling could be achieved in Sb₂Te₃ parallel device with P_max = 6.51 μW at ΔT = 106 K, and cooling of 4.1 K at 2 V. The 24-pair p-n couples series device could output maximum voltage of 313 mV at ΔT = 102 K. The power generation and the cooling of the devices show times enhanced TE performances than those consisting of common films. The results proved that introducing nanostructures into films is an effective choice to obtain high-efficient micro TE device.