Exploring physical exposures and identifying high-risk work tasks within the floor layer trade

Introduction

Floor layers have high rates of musculoskeletal disorders yet few studies have examined their work exposures. This study used observational methods to describe physical exposures within floor laying tasks.

Methods

We analyzed 45 videos from 32 floor layers using Multimedia-Video Task Analysis software to determine the time in task, forces, postures, and repetitive hand movements for installation of four common flooring materials. We used the WISHA checklists to define exposure thresholds.

Results

Most workers (91%) met the caution threshold for one or more exposures. Workers showed high exposures in multiple body parts with variability in exposures across tasks and for different materials. Prolonged exposures were seen for kneeling, poor neck and low back postures, and intermittent but frequent hand grip forces.

Conclusions

Floor layers experience prolonged awkward postures and high force physical exposures in multiple body parts, which probably contribute to their high rates of musculoskeletal disorders.     

Validity and reliability of a novel device for bilateral upper extremity functional measurements

Background and objective

This study was designed to establish the validity and reliability of a new device that measures bilateral shoulder and elbow range of motion (ROM) and grip force performance in vivo. A further aim was to investigate the control of inter-limb grip force coordination during isometric force-maintenance tasks. Validity of the ROM and grip force measurements was examined using a validated clinical goniometer and standard weights.

Subjects

Twenty-one healthy adults (six female, 15 male; mean ± standard deviation age = 23.05 ± 3.51) were recruited for this study.

Design

All subjects were asked to perform tests to evaluate the validity and reliability of ROM, grip force maximum voluntary contraction (MVC) and coordination control measurements.

Results

The ROM and grip force measurements were linearly correlated with criterion standards. For reliability testing, all of the intraclass correlation coefficient values were >0.99. The inter-limb grip force coordination control task showed that the force modulation timing during dominant-to-non-dominant hand transition was longer than the non-dominant-to-dominant hand transition (p < 0.05).

Conclusions

These results demonstrate that this device is valid and reliable when used to measure shoulder and elbow ROM and grip force of both hands. Isometric force-maintenance tasks also indicated changes in inter-limb grip force control.     

Coding warnings without interfering with dismounted soldiers' missions

Objectives

Warnings are an effective way to communicate hazard, yet they can also increase task demand when presented to operators involved in real-world tasks. Furthermore, in military-related tasks warnings are often given in codes to avoid counter-intelligence, which may foster additional working memory load.

Background

Adherence to warnings in the military domain is crucial to promote safety and reduce accidents and injuries. The empirical question arises as to how aspects of coding the warning may interfere with the primary task the individual is currently performing and vice versa.

Method

Six experimental conditions were designed to assess how warning-code storage format, response format, and increasing working memory demand (retention) affected both performance on the primary task and the rate of compliance to warnings, considered here as the secondary task.

Results

Results revealed that the combination of warning-code storage and response format affected compliance rate and the highest compliance occurred when warnings were presented as pictorials and responses were coded verbally. Contrary to the proposed hypotheses, warning storage format did not affect performance on the primary task, which was only affected by the level of working memory demand. Thus, the intra-modal warning storages did not interfere with the visual/spatial nature of the primary operational task. However, increase in working memory demand, by increasing the number of memorized warning codes, had an effect on both compliance rate and primary task performance.

Conclusions

Rather than warning code storage alone, it is the coupling of warning storage and response format that has the most significant effect on compliance.     

Assessing the ergonomic exposures for drywall workers

Objective

The study was conducted to assess the ergonomic exposures to risk factors that may lead to the reported musculoskeletal injuries (especially back, neck and wrist injuries) of drywall workers.

Methods

A hierarchical taxonomy for construction of drywall panel hanging (drywall panel fitting and installation) was developed with activities defined within the interior wall systems tasks (drywall panel, studs and insulation). Exposures were characterized for the drywall panel work with the PATH (Posture, Activity, Tools, and Handling) work-sampling observation method. Data on working postures were collected for three main body parts: legs, arms and trunk. Activities performed for each task, tools used, and manually handled loads were also recorded for each observation.

Results

The study identified several ergonomic exposures in interior systems construction. Several risk factors were especially prevalent in the drywall panel installation task: awkward body postures such as overhead arm posture, trunk flexion, and handling of heavy drywall panels. Some tasks were observed to have combinations of these musculoskeletal risk factors, such as drywall panel installation, where the workers lifted heavy drywall panels in awkward body postures. In addition, a safety hazard frequently resulted when a worker's foot was poorly supported on a ladder while lifting heavy drywall panels to hang them on the ceiling or upper wall.

Conclusion

The drywall panel installation task poses a severe threat to the safety and musculoskeletal health of the drywall workers. Much of this could be eliminated by reducing the burden of handling heavy and bulky drywall panels.

Relevance to industry

The construction industry is well-documented to have high rates of injury and musculoskeletal disorders. Design of appropriate interventions requires specific knowledge of which tasks and activities involve the highest levels of exposure to relevant factors. Assessment of such factors in drywall panel hanging has provided data that will be useful to evaluate the ergonomics efficacy of future changes in task processes or tools. Feasible solutions appear to exist; effectiveness trials and worker input are needed in order to evaluate whether they could eliminate the observed exposures.     

Kinematic and electromyographic differences between mouse and touchpad use on laptop computers

Background

Numerous studies have compared the postures and muscular activities induced by the various input devices available. To the authors' knowledge, no studies have yet compared upper body posture and movement, sEMG activity and muscle co-contractions induced by use of a mouse or of a touchpad.

Objective

The aim of this study was to compare posture, joint excursion and sEMG activity when using a laptop equipped with a mouse or a touchpad.

Methods

Trunk and upper arm posture, ranges of motion and muscle activities were measured in ten subjects during two standardized tasks.

Results

Mouse use induced larger shoulder abduction than touchpad use. On the other hand, when a touchpad was used, the upper arm joints were bound and fixed to a greater extent than during mouse use. Touchpad users are forced to maintain a more static posture. The upper arm electromyography results clearly indicate that touchpad use requires more stabilization than mouse use.

Conclusion

Motor tasks executed by means of the mouse allow a greater range of motions and reduce the biomechanical stress thanks to the greater postural mobility, even though the posture is less neutral. The results of our study tend to suggest that an external mouse should be preferred to the touchpad by frequent users of laptops.

Relevance to industry

This study is a suggestion for IT companies to give customers information of possible advantages using an external mouse. Furthermore our data highlight the importance of providing a mouse to all laptop users in order to reduce biomechanical risks.     

Emergency department utilization can indicate early diagnosis of digestive tract cancers: A population-based study in Taiwan

Background and objective

Patients who visit emergency department (ED) may have symptoms of occult cancers.

Methods

We studied a random cohort of one million subjects from Taiwan National Health Insurance Research Database between 2000 and 2008 to evaluate the ED utilization of individuals who were subsequently diagnosed with digestive tract cancers. The case group was digestive tract cancer patients and the control group was traumatic fracture patients. We reviewed record of ED visits only from 4 to 15 months before the cancer diagnoses.

Results

There were 2635 and 6665 in the case and control groups respectively. Patients’ adjusted odds ratio with 95% confidence interval for the case group were 1.36 (1.06–1.74) for Abdominal ultrasound, 2.16 (1.61–2.90) pan-endoscopy, 1.72 (1.33–2.22) guaiac fecal-occult blood test, 1.42 (1.28–1.58) plain abdominal X-rays, 1.20 (1.09–1.32) SGOT, 1.27 (1.14–1.40) SGPT, 1.66 (1.41–1.95) total bilirubin, 2.41 (1.89–3.08) direct bilirubin, 1.21 (1.01–1.46) hemoglobin and 3.63 (2.66–4.94) blood transfusion, respectively. Blood transfusion in the ED was a significant predictor of the individual subsequently diagnosed with digestive tract cancer.

Conclusions

The health system could identify high risk patients early by real-time review of their ED utilization before the diagnosis of digestive tract cancers. We proposed a follow-up methodology for daily screening of patients with high risk of digestive tract cancer by informatics system in the ED.     

Calibrating Borg scale ratings of hand force exertion

A study was conducted to assess the efficacy of calibrating subjective worker ratings of hand exertions to reduce error in estimates of applied force. Twenty volunteer subjects applied pinch and power grip forces corresponding to their perceptions of different Borg CR-10 scale levels using both "grip-to-scale" and "guided-grip" procedures. These data were used separately to define relationships between scale ratings and actual force application. Two gripping tasks were performed and corresponding subjective hand force ratings were calibrated using the grip-to-scale calibration data. Results showed that the mean estimation error for a 44.5 N (10 lb) power grip task was significantly reduced from 142.8 (+/-69.0) to 62.3 (+/-58.3) N. The guided-grip calibration method also significantly reduced rating error for the power grip task, however the estimates were biased toward zero. Neither calibration procedure improved rating accuracy of an 8.9 N (2 lb) pinch grip task. The study results indicate that calibration of hand force ratings using the grip-to-scale procedure may improve the accuracy of hand exertion measurements using the Borg CR-10 scale.     

The relationship between usage intention and adoption of electronic health records at primary care clinics

Objective

Despite of emerging evidence that electronic health records (EHRs) can improve the clinical quality, enhances patient safety and efficiency. Most physicians in primary health care clinics in the Taiwan do not currently adopt EHR at their clinic practices. We aim to measure the relationship between usage intention and adoption behavior.

Study design and methods

We used structured questionnaires distributed both EHRs adopter and non-adopter group to the primary health care physicians which participated in the DOH project to establish the information exchange environment across Taiwan. The response rate of adopter and non-adopter is 54.7% and 55.0% respectively.

Measurements

EHRs adoption behavior.

Results

The EHRs adopter group has higher intention than non-adopter (p = 0.003). From the result of logistic regression analyses, we found the key factors affecting physicians’ adoption pattern were intention to use (OR: 2.85; 95% CI: 2.30–3.54). In addition, higher perceived usefulness (OR: 1.29; 95% CI: 1.06–1.56) and perceived ease to use (OR: 1.48; 95% CI: 1.22–1.79) increase adoption of EHR found.

Conclusion

The intention to use EHR, perceived usefulness and ease to use of primary care physicians were found as key factors influencing EHRs adoption. Thus, we suggest that government should promote the potential benefits of EHR and enhance physicians’ willingness to adopt the EHRs at their clinic practices.     

Infection risk in patients with rheumatoid arthritis treated with etanercept or adalimumab

Objectives

To compare the risk of infection for rheumatoid arthritis (RA) patients who took etanercept or adalimumab medication in a nationwide population.

Methods

RA patients who took etanercept or adalimumab were identified in the Taiwan's National Health Insurance Research Database. The composite outcome of serious infections, including hospitalization for infection, reception of an antimicrobial injection, and tuberculosis were followed for 365 days. A Kaplan–Meier survival curve with a log-rank test and Cox proportional hazards regression were used to compare risks of infection between the two cohorts of tumor necrosis factor (TNF)-α antagonists users. Hazard ratios (HRs) were obtained and adjusted with propensity scores and clinical factors. Sensitivity analyses and subgroup analyses were also performed.

Results

In total, 1660 incident etanercept users and 484 incident adalimumab users were eligible for the analysis. The unadjusted HR for infection of the etanercept users was significantly higher than that of the adalimumab users (HR: 1.93; 95% confidence interval (CI): 1.09–3.42; p = 0.024). The HRs were 2.04 (95% CI: 1.14–3.65; p = 0.016) and 2.02 (95% CI: 1.13–3.61; p = 0.018) after adjusting for propensity scores and for propensity scores in addition to clinical factors, respectively. The subgroup analyses revealed that HRs for composite infection was significantly higher in patient subgroups of older age, female, as well as patients who did not have DM, COPD, and hospitalization history at the baseline.

Conclusion

In this head-to-head cohort study involving a nationwide population of patients with RA, etanercept users demonstrated a higher risk of infection than adalimumab users. Results of this study suggest the possible existence of an intra-class difference in infection risk among TNF-α antagonists.     

A web-based learning tool improves student performance in statistics: A randomized masked trial

Background

e-status is a web-based tool able to generate different statistical exercises and to provide immediate feedback to students’ answers. Although the use of Information and Communication Technologies (ICTs) is becoming widespread in undergraduate education, there are few experimental studies evaluating its effects on learning.

Method

All of the students (121) from an introductory course for statistics in dentistry were randomly assigned to use the tool with one of two 6-problem sets, known as types A and B. The primary endpoint was the grade difference obtained in the final exam, composed of two blocks of questions related to types A and B. The exam evaluator was masked to the intervention group.

Results

We found that the effect of e-status on the student grade was an improvement of 0.48 points (95% CI: 0.10–0.86) on a ten-point scale. Among the 94 students who actually employed e-status, the effect size was 0.63 (95% CI: 0.17–1.10).

Conclusions

It is feasible to formally assess the learning effect of an innovative tool. Providing e-status exercises to students has a direct effect on learning numerical operations related to statistics. Further effects on higher cognitive levels still have to be explored.     

A finger motion model for reach and grasp

This study aimed to develop a model that describes human finger motion for simulation of reach and grasp for selected objects and tasks. Finger joint angles and timing of their changes were measured for six subjects as they reached 20-40 cm and grasped cylindrical handles (1.3-10.2 cm D) of varying orientation (vertical/axial). The empirical results from multiple regression analyses served as inputs to allow a fourth order polynomial to predict motion of each finger joint. The proposed model showed good fit with observations, with high coefficients of determination from 0.54 to 1 and reasonable errors from 0.04° to 5.44° for all conditions considered. The proposed finger motion model was implemented in an existing kinematic hand model to employ a contact algorithm for refined prediction of grip posture and to illustrate its predictive power by graphically displaying the opening and closing of the hand.

Relevance to industry

Finger joint motions during reach and grasp are needed for prediction of (1) tendon excursions for study of work-related musculoskeletal disorders, (2) required space for the hand, (3) finger locations on work objects, and (4) hand grip postures and strength.     

Costs of occupational musculoskeletal disorders (MSDs) in the United States

Background

For the years 1992–2010 musculoskeletal disorders (MSDs) accounted for 29–35% of all occupational injuries and illnesses involving days away from work in the United States (US) (AFL-CIO, 2012). According to the American Federation of Labor and Congress of Industrial Organizations (AFL-CIO) 2012 report ‘Death on the Job’, for the years 1992 through 2010 the percent of cases involving MSDs in private industry were highest in 2000 (35%) and lowest in 2007 (29%). In 2010, the median number of days away from work for MSDs was 11 compared to 8 for all occupational injury cases involving days away from work; the median number of days away from work for Carpal Tunnel Syndrome (CTS) was 25, more than three times as high as for all other BLS injuries involving days away from work (BLS, 2011). This study estimated the costs of work related MSDs, and given that the number of days lost due to CTS is very high, it also estimated the costs of CTS separately in the United States (US) for the years 2003 through 2007.

Methods

The costs of work related MSDs and CTS in the US were estimated using the cost-of-illness, human capital method (Leigh et al., 2000), using some of the costs from the literature. This method decomposes costs into direct and indirect categories. Estimates of total cost of MSDs and CTS were obtained from the product of average costs of MSDs and CTS and the number of MSDs and CTS. The number of MSDs and CTS were obtained from BLS data.

Results

The number of reported work-related MSDs declined from 435,180 in 2003 to 335,390 in 2007 and the reported number of CTS also declined from 22,110 in 2003 to 11,920 in 2007. The direct costs of MSDs and CTS were respectively $1.5 billion and $0.1 billion for the year 2007. The indirect costs were $1.1 billion and $0.1 billion for MSDs and CTS respectively for the year 2007.

Discussion

This study found that the total costs of work-related MSDs and CTS declined during the period 2003 through 2007 but the average costs per case went up signifying that medical costs and other associated costs increased during this period.

Relevance to industry

The costs of MSDs are important to the industries too as a significant part of these costs are borne by the employers. Industries with higher prevalence of MSDs are affected more in terms of lost productivities due to the employees' days away from work because of MSDs. In cases of MSDs causing permanent disabilities, new hiring and training costs are also a part of the losses experienced by the employers.     

Influence of wearing an unstable shoe on thigh and leg muscle activity and venous response in upright standing

Purpose

To quantify the effect of unstable shoe wearing on muscle activity and haemodynamic response during standing.

Methods

Thirty volunteers were divided into 2 groups: the experimental group wore an unstable shoe for 8 weeks, while the control group used a conventional shoe for the same period. Muscle activity of the medial gastrocnemius, tibialis anterior, rectus femoris and biceps femoris and venous circulation were assessed in quiet standing with the unstable shoe and barefoot.

Results

In the first measurement there was an increase in medial gastrocnemius activity in all volunteers while wearing the unstable shoe. On the other hand, after wearing the unstable shoe for eight weeks these differences were not verified. Venous return increased in subjects wearing the unstable shoe before and after training.

Conclusions

The unstable shoe produced changes in electromyographic characteristics which were advantageous for venous circulation even after training accommodation by the neuromuscular system.     

A study of cyclic dependencies on defect profile of software components

Background

Empirical evidence shows that dependency cycles among software components are pervasive in real-life software systems, although such cycles are known to be detrimental to software quality attributes such as understandability, testability, reusability, build-ability and maintainability.

Research goals

Can the use of extended object-oriented metrics make us better understand the relationships among cyclic related components and their defect-proneness?

Approach

First, we extend such metrics to mine and classify software components into two groups – the cyclic and the non-cyclic ones. Next, we have performed an empirical study of six software applications. Using standard statistical tests on four different hypotheses, we have determined the significance of the defect profiles of both groups.

Results

Our results show that most defects and defective components are concentrated in cyclic-dependent components, either directly or indirectly.

Discussion and conclusion

These results have important implications for software maintenance and system testing. By identifying the most defect-prone set in a software system, it is possible to effectively allocate testing resources in a cost efficient manner. Based on these results, we demonstrate how additional structural properties could be collected to understand component's defect proneness and aid decision process in refactoring defect-prone cyclic related components.     

Prevalence of carpal tunnel syndrome among employees at a poultry processing plant

Objective

To determine prevalence of carpal tunnel syndrome (CTS) among poultry processing employees while taking into account non-occupational factors and assess any association between CTS prevalence and exposure groups.

Methods

Performed a cross-sectional survey to assess CTS (n = 318). A CTS case was defined as an employee with self-reported CTS symptoms, an abnormal hand symptom diagram, and an abnormal nerve conduction study (NCS). Log-binomial regression was used to estimate prevalence ratios.

Results

Three hundred and one participants had sufficient symptom information or NCS data to be classified. 126 (42%) of 301 participants had evidence of CTS. In the adjusted analysis, the highest exposure group had CTS prevalence that was significantly higher than that for the lower exposure group [PR: 1.61; 95% CI = (1.20, 2.17)].

Conclusions

Increasing levels of hand activity and force were associated with increased CTS prevalence among participants. Recommendations were provided to reduce exposure to these risk factors.     

Machine learning-based assessment tool for imbalance and vestibular dysfunction with virtual reality rehabilitation system

Background and objective

Dizziness is a major consequence of imbalance and vestibular dysfunction. Compared to surgery and drug treatments, balance training is non-invasive and more desired. However, training exercises are usually tedious and the assessment tool is insufficient to diagnose patient's severity rapidly.

Methods

An interactive virtual reality (VR) game-based rehabilitation program that adopted Cawthorne–Cooksey exercises, and a sensor-based measuring system were introduced. To verify the therapeutic effect, a clinical experiment with 48 patients and 36 normal subjects was conducted. Quantified balance indices were measured and analyzed by statistical tools and a Support Vector Machine (SVM) classifier.

Results

In terms of balance indices, patients who completed the training process are progressed and the difference between normal subjects and patients is obvious.

Conclusions

Further analysis by SVM classifier show that the accuracy of recognizing the differences between patients and normal subject is feasible, and these results can be used to evaluate patients’ severity and make rapid assessment.     

Who benefits from simulator training: Personality and heart rate variability in relation to situation awareness during navigation training

Objective

This study tested the relationship between individual differences and Situation Awareness (SA) during training in a navigation simulator.

Background

Simulators have become an important tool in the training and education of maritime personnel with a view to improving decisions and performance. There are a few, inconclusive empirical studies that have focused on mapping personality characteristics and their link to the ability to generate and maintain SA during simulator training.

Method

Thirty-six first-year students from the Royal Norwegian Navy Officer Candidate School participated in the study. SA was measured using both subjective and observer ratings.

Results

The results indicated that low scores on Neuroticism and high scores on Extraversion and Conscientiousness (resilient personality type) predicted both subjective and observer-rated SA. Furthermore, participants with high SA were able to modulate their Heart Rate Variability (HRV), with suppression of HRV during navigation training as well showing recovery of HRV.

Application

The potential applications of this research include the assessment of personality differences as a tool in selecting navigators, and the use of HRV as an objective index of adaptability to environmental demands.     

Pilot task-based assessment of noise levels among firefighters

Purpose

Over one million American firefighters are routinely exposed to various occupational hazards. While efforts have been made to identify and reduce some causes of injuries and illnesses among firefighters, relatively little has been done to evaluate and understand occupational noise exposures in this group. The purpose of this pilot study was to apply a task-based noise exposure assessment methodology to firefighting operations to evaluate potential noise exposure sources, and to use collected task-based noise levels to create noise exposure estimates for evaluation of risk of noise-induced hearing loss by comparison to the 8-hr and 24-hr recommended exposure limits (RELs) for noise of 85 and 80.3 dBA, respectively.

Methods

Task-based noise exposures (n = 100 measurements) were measured in three different fire departments (a rural department in Southeast Michigan and suburban and urban departments in Northern California). These levels were then combined with time-at-task information collected from firefighters to estimate 8-hr noise exposures for the rural and suburban fire departments (n = 6 estimates for each department). Data from 24-hr dosimetry measurements and crude self-reported activity categories from the urban fire department (n = 4 measurements) were used to create 24-hr exposure estimates to evaluate the bias associated with the task-based estimates.

Results

Task-based noise levels were found to range from 82 to 109 dBA, with the highest levels resulting from use of saws and pneumatic chisels. Some short (e.g., 30 min) sequences of common tasks were found to result in nearly an entire allowable daily exposure. The majority of estimated 8-hr and 24-hr exposures exceeded the relevant recommended exposure limit. Predicted 24-hr exposures showed substantial imprecision in some cases, suggesting the need for increased task specificity and highlighting the variability of firefighting noise exposures.

Conclusions

The results indicate potential for overexposure to noise from a variety of firefighting tasks and equipment, and suggest a need for further exposure characterization and additional hearing loss prevention efforts.

Relevance to industry

Firefighters may be at risk of noise-induced hearing loss, which can affect their fitness for duty and ability to respond effectively to emergencies. The results of this study suggest that additional efforts at hearing loss prevention among firefighters are warranted.