Fostering critical thinking and reflection through blog‐mediated peer feedback

The introduction of digital literacy practices has created a tension in academia, with many academics challenging the view that critical thinking can be fostered on social networks. A quasi‐experimental study was conducted on two sections of university‐level writing classrooms to determine if there were meaningful differences in the quality of writing and peer feedback generated through in‐class draft workshops using traditional methods as compared to draft workshops using a blogging platform. The results indicated that blogs produced a higher quality of writing as measured by grades, f(42) = 11.512, p < .002 and acceptance scores, f(42) = 8.364, p < .006. Furthermore, blog‐mediated peer workshops produced a statistically significantly higher number of critical comments, f(42) = 120.438, p < .000; and directive comments, f(42) = 33.861, p < .000. There were no statistically significant differences in the number of editing comments, f(42) = .001, p < .974, and traditional draft workshops produced a statistically significant higher number of naïve comments, f(42) = 14.119, p < .001. Within the study, critical comments were found to correlate positively with learning outcomes, b = 1.115, t(41) = 2.716, p < .01. The findings suggest that blogging software improved learner performance and fostered complex literacy skills.     

A job-shop problem with one additional resource type

We consider a job-shop scheduling problem with n jobs and the constraint that at most p<n jobs can be processed simultaneously. This model arises in several manufacturing processes, where each operation has to be assisted by one human operator and there are p (versatile) operators. The problem is binary NP-hard even with n=3 and p=2. When the number of jobs is fixed, we give a pseudopolynomial dynamic programming algorithm and a fully polynomial time approximation scheme (FPTAS). We also propose an enumeration scheme based on a generalized disjunctive graph, and a dynamic programming-based heuristic algorithm. The results of an extensive computational study for the case with n=3 and p=2 are presented.     

Prevalence and associated risk factors of low‐back pain in textile fishing net manufacturing

This study examined the 7‐day prevalence of low‐back pain (LBP; i.e., pain within the preceding week of the survey) and identified associated factors, including working posture, for a population of fishing net assembly workers. LBP is a serious problem in manual work with high prevalence and affects worker absenteeism. A cross‐sectional survey study was conducted among textile fish net industrial workers using a structured questionnaire (hand delivered by researchers and independently completed by workers). The 7‐day prevalence of LBP in this study was 68.6% (95% confidence interval [CI]: 65 to 72%). Work factors significantly related to LBP included prolonged standing and walking. Workers 35 years old or greater were significantly more likely to experience LBP within the past 7 days preceding the survey than were those 34 years old or less (adjusted odds ratio [ORadj] = 4.9; 95% CI: 2.4 to 10.3; p = .0001). Other significant factors associated with LBP included posture position, specifically stooping (ORadj = 1.6; 95% CI: 1.0 to 2.3; p = .033), lifting (ORadj = 1.6; 95% CI: 1.1 to 2.4; p = .025), and high concentration jobs (ORadj = 1.9; 95% CI: 1.3 to 2.7; p = .001), respectively. LBP among textile fish net workers is a serious problem meriting ergonomic evaluation and design of control measures for reducing worker exposure to risk factors. Work characteristics were more significantly associated with LBP than were individual characteristics. Factories need to consider adjusting work conditions to prevent worker low‐back injuries. © 2012 Wiley Periodicals, Inc.     

Ground reaction force and required friction during stair ascent and descent

A stair climbing experiment was performed using a four‐stair instrumented stairway. A force platform was mounted in the first stair. Four floor surfaces, including the original force platform surface and three additional floor coverings on the platform, were tested. Human subjects wore the same type of lab shoes and ascended and descended the stairway. Their ground reaction forces were collected. The results showed that when descending, the double‐stair condition resulted in significant (p < .0001) higher vertical ground reaction force at foot landing as compared to the single‐stair condition. The vertical ground reaction force at foot push‐off for stair ascent were significantly (p < .0001) higher than those for stair descent. The mean required coefficient of friction ranged from 0.086 to 0.245 and from 0.051 to 0.246 for foot landing and foot push‐off spots, respectively. Stair descent required significant (p < .001) higher friction than stair ascent both at foot landing and push‐off. Double‐stair stepping required higher friction than single‐stair stepping. Stair descent should be of primary concern in assessing the risk of slip‐ and fall‐related incidents on stairway, and double‐stair descent should be avoided.     

The Effects of Task Interruption on Human Performance: A Study of the Systematic Classification of Human Behavior and Interruption Frequency

Interruptions are prevalent phenomena in modern working environments; yet, few interruption studies have been conducted on different types of human tasks. A study using computer‐based human behavior tasks was carried out to investigate the effects of interruptions with 4 different primary‐interrupting task sets. The tasks used in this study were determined by cognitive and motor skill processes based on human behavior classification theory. The results showed that interruption effects were most negative in cognitive/cognitive task sets, and skill/cognitive task sets showed the least amount of effects in task completion time, F(3, 332) = 77.88, p < .001. In error rate performance, skill/skill task sets showed the highest rate, and error rates for cognitive primary task sets (cognitive/cognitive and cognitive/skill task sets) were not significantly different, F(1, 42) = 41.18, p < .001; F(1, 42) = 3.56, p = 0.0661. Interruption frequency also negatively affected task performance, F(1, 412) = 89.88, p < .001, but skill tasks’ quantitative performance did not show significant effects at different interruption frequencies, F(1, 187) = 3.78, p = .0534. The results showed that interruptions increase more time to complete in cognitive tasks and produce more errors in skill tasks. Also, similar types of primary‐interrupting tasks were more susceptible from interruptions. Thus, based on task composition of work process, we can estimate different effects from the interruptions and memory load, and task similarity in primary‐interrupting task relationship were considered a main factor.     

Criteria for the reintegration in the workforce of workers with musculoskeletal disorders of the upper limbs,based on preliminary practical experience

This paper presents a preliminary study on the return to the workforce of employees with WMSDs of the upper limbs, and their reallocation to jobs with ‘low exposure’. The study, which is still underway, involves a large engineering firm and includes some 100 workers affected by WMSDs. The trial involved: providing a definition of the criteria for characterizing ‘accommodating’ jobs (i.e. frequency of action < 20 actions/min; virtual absence of other risk factors such as force, awkward posture, inadequate pauses, etc.); effectively identifying jobs meeting such criteria (or jobs which, with minimal modifications, could be made suitable); classifying WMSD workers according to the type and severity of the disorder; matching WMSD workers with the jobs best suited to them; specific training for the workers and their supervisors; carrying out a follow-up of the return of WMSD workers to the workforce in organizational terms (i.e. the need for further modifications to equipment or procedures) and clinical terms (i.e. symptom patterns, acceptability of the condition). The preliminary results, 6–12 months after the start of the trial, are extremely encouraging, and show that when workers return to the workforce in jobs that fully meet defined criteria, a significant prevalence of ‘improvements’ are reported among the workers involved. The investigation will need to be extended but it already shows quite convincingly that it is possible for workers with what can be described as a ‘reduced working capacity’ to remain ‘productive’ (albeit in jobs featuring a lower exposure potential than the acceptable threshold for ‘healthy’ workers).     

The accuracy of self-report and trained observer methods for obtaining estimates of peak load information during industrial work

The purpose of this study was to determine how well self-report (questionnaire=QR) and trained observer (checklist=OBS) data recording methods compared with more expensive video analysis (VID) for estimating various peak physical loading exposure variables on the low backs of 99 employees during work in an automobile assembly plant. The variables studied were L4/L5 spine compression and shear forces, L4/L5 moment, trunk angle, and hand load. Peak low back loads associated with the working postures of, and the applied loads on, each worker were estimated using a 2D biomechanical model that could accommodate inertial forces acting in various directions on the hands independently. Correlations between the VID and OBS methods were greater for each variable than between VID and QR methods, with ranges in coefficients from 0.6 to 0.8, and 0.1 to 0.4, respectively, giving a discouraging impression of the QR, and the OBS method to a lesser degree, for peak low back exposure assessment. Despite the better performance of OBS method for individuals, it was still only able to account for between 36% and 64% of the variance relative to the VID method. When all workers were considered as a single group, compression and shear forces, moment and hand load estimates were the same regardless of method used to collect the data. Self-reported trunk flexion was significantly greater than that reported by trained observers or on video (p<0.0001).Relevance to industryConsiderable time and expense could be saved in large scale studies if it were possible to rely on worker's reports or observation of the physical demands of their jobs instead of traditional video and biomechanical analyses. Assessments of peak exposure of individuals using the self-report and observation methods were discouraging. Analysis of a single group proved more promising, but other groups need to be studied. Interview assisted self-reports may help to improve assessments of individuals and also need to be investigated in the future.     

Biomechanics and Kinematic Responses of the Upper Extremity during Isotonic and Isokinetic Wrench‐Turning Tasks

The purpose of this study was to investigate the impact of using a wrench under isotonic (constant torque) and isokinetic (constant speed) task modes (TM) at three work surface inclinations (WSI) (0°, 45°, and 90°) on the biomechanical (muscle activity) and kinematic (joint posture) responses of the upper extremity. The muscle activity of seven muscles (trapezius posterior deltoid, anterior deltoid, triceps, biceps, brachioradialis, and flexor digitorium) and posture of four body segments (shoulder adduction/abduction, elbow flexion/extension, forearm supination/pronation and wrist flexion/extension) were obtained using surface electromyography and motion tracking, respectively. WSI showed a statistically significant effect on the muscle activity of the posterior deltoid (p = .038), triceps (p = .016), and biceps (p = .021). The least muscle activity was recorded at the 0° WSI in the isotonic TM. WSI had a significant impact on the supination (p = .017) and pronation (p = .011) of the forearm. The 45° WSI had the least impact on forearm postures. Wrenches are widely used in industries, including automobile service and maintenance, manufacturing, carpentry, and general repair work. Their usage poses risks for the development of musculoskeletal disorders in the upper extremity. In spite of this, knowledge of their physical demands and associated impact on the upper extremity has not been well documented. This study provides empirical evidence on the biomechanical and kinematic responses of selected upper extremity muscles and limb segments and highlights task performance and workstation design factors that elicit undue levels of these responses. The results of this work can provide guidance for ergonomic interventions such as optimized task design and/or improved workstation design when it comes to wrench‐turning tasks.     

Perception of Hand Force in Power Grip for Females

Borg's rating of perceived exertion (RPE) and category ratio (CR‐10) scales are commonly used to quantify perceived muscular exertion for body segments. Twenty females participated in an experiment to study the power grip force at four perceived exertion levels using either dominant or nondominant hand under two posture conditions. It was found that the subjects tended to apply a higher power grip force (100% of perceived maximum voluntary contraction) than the levels they were requested to apply. The power grip forces between dominant and nondominant hands at low hand exertion levels were negligible. The grip forces between the two hands were significantly different when the exertion level was nearly maximal. Linear regression models were established for the subjects to link the relationship between the perceived hand exertion and measured grip force, hand used, and hand/arm posture. All the models were statistically significant (p < 0.0001) with R² values 0.97 or higher. These models provided better estimates in perceived hand exertion for dominant hand than for nondominant hand. A follow‐up experiment was conducted to measure the subjective rating of both the CR‐10 and RPE when a 98 N grip force was applied. It was found that the subjects reported higher exertion levels when they were using the CR‐10 scale than when they were using the RPE scale. © 2011 Wiley Periodicals, Inc.     

The effects of force and exertion duration on duty cycle time: Implications for productivity

Ergonomics has positive effects on both physical health and productivity, but estimating productivity benefits is difficult at the task design/redesign stage. Rest‐allowance prediction models are not suitable for repetitive, short‐cycle dynamic tasks, and methods–time measurement (MTM) techniques are limited in their suitability for considering ergonomics risk factors such as posture and force. The purpose of this study was to investigate the relationship between force and exertion duration on self‐selected duty cycle time and discomfort. Twenty‐one participants completed repetitive, upper‐limb exertion treatments, each of a 10‐minute duration. Five levels of force (10, 20, 40, 65, and 80% maximum voluntary contraction [MVC]) and exertion period (1, 2, 4, 6.5, and 8 seconds) were investigated. The psychophysical adjustment method was used whereby participants self‐selected a work pace for the second half of each treatment. Duty cycle, derived from the self‐paced cycle time, was the measure of productivity effects in the experiment. Analysis of variance revealed a significant effect on duty cycle time for force, exertion period, and their interaction (each p < 0.0001). Friedman's test indicated a significant effect of force (p < 0.0001) and exertion period (p < 0.0001) on discomfort. Spearman's correlation analysis showed a strong correlation between discomfort and duty cycle time (p < 0.05). Multiple regression analysis was used to develop a predictive model for duty cycle time based on force and exertion period, and this was a good fit to the data (R² = 0.98, p < 0.05). Profiles were generated presenting zones of acceptable self‐selected duty cycle times based on force and exertion duration. © 2010 Wiley Periodicals, Inc.     

Effects of computer mouse design and task on carpal tunnel pressure

Computer mouse use has become an integral part of office work in the past decade. Intensive mouse use has been associated with increased risk of upper extremity musculoskeletal disorders, including carpal tunnel syndrome. Sustained, elevated fluid pressure in the carpal tunnel may play a role in the pathophysiology of carpal tunnel syndrome. Carpal tunnel pressure was measured in 14 healthy individuals while they performed tasks using three different computer mice. Participants performed a multidirectional dragging (‘drag and drop’) task starting with the hand resting (static posture) on the mouse. With one mouse, an additional pointing (‘point-and-click’) task was performed. All mice were associated with similar wrist extension postures (p= 0.41) and carpal tunnel pressures (p= 0.48). Pressures were significantly greater during dragging and pointing tasks than when resting the hand (static posture) on the mouse (p= 0.003). The mean pressures during the dragging tasks were 28.8- 33.1 mmHg, ～ 12 mmHg greater than the static postures. Pressures during the dragging task were higher than the pointing task (33.1 versus 28.0 mmHg), although the difference was borderline non-significant (p= 0.06). In many participants the carpal tunnel pressures measured during mouse use were greater than pressures known to alter nerve function and structure, indicating that jobs with long periods of intensive mouse use may be at an increased risk of median mononeuropathy. A recommendation is made to minimize wrist extension, minimize prolonged dragging tasks and frequently perform other tasks with the mousing hand.     

Low back pain in farmers: The association with agricultural work management,disability, and quality of life in Korean farmers

This study aimed to identify the associations among low back pain (LBP), LBP‐related disability, agricultural working condition management, and quality of life (QOL) in Korean farmers. Demographic information, agricultural work management, and outcomes of LBP were obtained by standardized questionnaires (Oswestry Disability Index [ODI] for disability and European Quality of Life‐5 Dimensions‐3‐Level version [EQ‐5D‐3L] for QOL). Presence of LBP was determined if the LBP had lasted longer than 1 week or had been more frequent than once a month, and presence of LBP‐related disability was determined if the ODI score was more than 12. Poor health checkups (OR [odds ratio] = 1.70–86, p < .05), were positively associated with LBP, and working at dawn (OR = 1.85–1.96, p < .05), was positively associated with LBP‐related disability after adjusting related demographic factors. EQ‐5D‐3L indexes were significantly lower in participants with LBP (0.83 ± 0.17 vs. 0.92 ± 0.06, p < .001) and disability (0.81 ± 0.18 vs. 0.93 ± 0.05, p < .001). This study showed that the presence of LBP was related to poor health checkups and that LBP‐related disability was related to a poor working time schedule. These results indicate poor QOL and suggest the need for coping strategies such as regular health checkups and a proper working time schedule.     

A comparison of managers' and safety delegates' perceptions of work environment priorities in the manufacturing industry

This study investigated the attention and priority accorded to factors of work environment within manufacturing companies, as perceived by managers and safety delegates at small‐ and medium‐sized enterprises. Representatives from 142 Swedish manufacturing companies answered a 43‐item questionnaire covering seven areas of the work environment and a priority‐ranking question of company interests. Respondents (n = 249) rated the present situation and the situation one year earlier, using a visual analogue scale. The findings showed that both managers and safety delegates ranked profitability as the main company interest. Respondents rated the priorities of the work environment currently as higher than one year earlier (p = <0.05). Managers rated the priorities of the work environment higher than did the safety delegates (p = <0.05). We conclude that the two professional roles, manager and safety delegate, differ in their perceptions regarding to what extent different work environment factors are being attended to. © 2011 Wiley Periodicals, Inc.     

Static friction properties between human palmar skin and five grabrail materials

The purpose of this study was to investigate the static friction properties between human palmar skin and five grabrail materials (chrome, stainless steel, power-coated steel, textured aluminium and knurled steel) for dry, wet and soapy hands. Thirty subjects (15 female, 15 male) participated in this study, their ages ranging from 19 to 45 years with a mean age of 28 years. The normal force, friction force, and coefficient of static friction were determined by measuring three-dimensional forces while slipping the palm of the hand over the surface of a grabrail. A repeated measures ANOVA indicated that gender, age, hand size and trial effect had no significant influence (p >0.05) on these results. The coefficient of friction (p <0.001) and friction force (p <0.001) were significantly lower when the hand was soapy than when it was dry or wet. The normal force applied when the hand was soapy was significantly greater (p <0.001) than when it was dry or wet. No significant difference was found between dry and wet hands. The two textured materials displayed superior friction properties when the hand was soapy, while the smooth materials performed best when the hand was dry.     

Investigating the effect of custom‐made insoles and exercises on lower limb and back discomfort in assembly‐line workers in a rubber tire factory: A randomized controlled trial

Many occupations require standing for prolonged periods, which can be a major contributor to musculoskeletal problems and cause disturbances in different parts of the body, especially the lower back and lower extremities. The aim of this study was to investigate the effect of custom‐made insoles and exercise training on the lower limb and lower back discomfort in workers on a production line at a rubber tire factory. One hundred male workers (mean age 35.96 years, work experience of 10.62 years, standing time 6.58 hr) participated in this randomized controlled trial. The men were randomly assigned to one of four groups: (a) custom‐made insole plus lower limb exercises, (b) insoles only, (c) lower limb exercises only, and (d) no intervention. Discomfort level was recorded with a visual analog scale and a body map. The data were analyzed with analysis of covariance. The results showed a significant difference in discomfort levels between groups in the lower back (p = .001), thigh (p = .001), and knee (p = .001) areas. The combined insole and exercise group had less discomfort in the lower back, thigh, and knee. In the group that used the insole only without exercises, the discomfort level in the lower back area was reduced. The results indicate that the simultaneous use of insoles and exercises might be an effective intervention to reduce discomfort in the lower limbs and lower back in workers who remain standing for prolonged periods.     

Using a sparse promoting method in linear programming approximations to schedule parallel jobs

In this paper, we tackle the well‐known problem of scheduling a collection of parallel jobs on a set of processors either in a cluster or in a multiprocessor computer. For the makespan objective, that is, the completion time of the last job, this problem has been shown to be NP‐hard, and several heuristics have already been proposed to minimize the execution time. In this paper, we consider both rigid and moldable jobs. Our main contribution is the introduction of a new approach to the scheduling problem, based on the recent discoveries in the field of compressed sensing. In the proposed approach, all possible positions and shapes of the jobs are encoded into a matrix, and the scheduling is performed by selecting the best columns under natural constraints. Thus, the solution to the new scheduling formulation is naturally sparse, and we may use appropriate relaxations to achieve the optimization task in the quickest possible way. Among many possible relaxation strategies, we choose to minimize the ℓ_p‐quasi‐norm for p∈(0,1). Minimization of the ℓ_p‐quasi‐norm is implemented via a successive linear programming approximation heuristic. We propose several new algorithms based on this approach, and we assess their efficiency through simulations. The experiments show that the scheme outperforms the classic Largest Task First list based algorithm for scheduling small to medium instances but needs improvements to compete on larger numbers of jobs. Copyright © 2014 John Wiley & Sons, Ltd.     

Optimally competitive list batching

Batching has been studied extensively in the offline case, but applications such as manufacturing or TCP acknowledgment often require online solutions.We consider online batching problems, where the order of jobs to be batched is fixed and where we seek to minimize the sum of the completion times of the jobs. We present optimally competitive online algorithms for both s-batch and p-batch problems, and we also derive results for certain naturally occurring special cases, such as the case of unit processing times.     

Kinetic changes associated with load carriage using two rucksack designs

This study assessed changes in kinetics from unloaded walking associated with load carriage using both a traditional and a new rucksack design that incorporates front balance pockets (AARN). Nine subjects walked at 3(±0.05) km.h^-1 over a force plate unloaded and carrying 25.6 kg in each of the rucksacks. The order of trials was randomized and speed-controlled by use of photoelectric cells and a millisecond timer. Anteroposterior and vertical ground reaction forces were analyzed using repeated measures ANCOVA (speed covariate). There was a trend for the AARN pack to elicit a shorter support time than the traditional pack, 1.025±0.049 versus 1.037±0.06 s (p = 0.056), while the unloaded condition produced the shortest support time, 1.016±0.04 s. Both braking and propulsive forces for the rucksacks were significantly greater than for unloaded walking. While there was no significant difference between the packs for the braking force, the AARN pack produced a significantly lower (p < 0.05) propulsive force than the traditional rucksack, 0.79±0.2 versus 0.94±0.16 N.kg bodyweight^-1. Both rucksacks produced significantly greater (p < 0.001) vertical force peaks than unloaded walking, the increases being proportional to the increase in system weight. These findings indicate that there may be some advantage in terms of propulsive force production for the front/back system.     

Current‐mode ambient‐light sensing circuit using p‐type low‐temperature polycrystalline‐silicon TFTs and p‐i‐m diodes

Abstract— A current‐mode ambient‐light sensing circuit, which is composed of p‐intrinsic‐metal (p‐i‐m) diodes and p‐type low‐temperature polycrystalline‐silicon (LTPS) thin‐film transistors (TFTs) for autobrightness control of display panels. The proposed sensing circuit exhibits a wide dynamic range of 56 dB, while the output signal range is 1.8 times wider than that of a previously reported sensing circuit.     

Identification of the maximum acceptable frequencies of upper‐extremity motions in the sagittal plane

The present study examined the maximum acceptable frequencies (MAFs; motions/min) of upper‐extremity motions in the sagittal plane at different forces. A dumbbell of 9.8 or 39.2 N was rotated by the arm about the shoulder, the forearm about the elbow, and the hand about the wrist; a dynamometer was pressed to 2.45 or 9.8 N by the index finger. Seventeen right‐handed Korean men in their 20s without any history of musculoskeletal disorders received 1 hour of individual training and conducted each upper‐extremity task for 30 minutes a day, assuming they were on an incentive basis. The participants determined their MAFs for 8 hours of work by the self‐adjustment method, and work pulse (change in heart rate; beats per minute [bpm]) and rating of perceived exertion (RPE) were measured. For a limited set of conditions, the reproducibility of the MAF experimental protocol was found satisfactory (r = 0.97; interclass correlation coefficient > 0.95). The average MAFs of arm, forearm, hand, and index finger motions were 24, 45, 56, and 128 at their low force level and 9, 20, 30, and 66 at their high force level. The average work pulses of arm, forearm, and hand motions were 3.0, 2.1, and 1.5 times that of index finger motion (4.2 bpm at their low force level and 5.7 bpm at their high force level). The maximum average RPEs at the upper‐extremity regions ranged from 2.1 (weak) to 3.1 (moderate) in Borg's CR‐10 scale. © 2009 Wiley Periodicals, Inc.