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Musculoskeletal disorders (MSDs) are associated with sitting postures. The assessment and prevention of risk factors for workplace exposure are indispensable aspects of reducing the occurrence of MSDs. This paper proposes an ergonomic assessment method of risk factors for MSDs associated with sitting postures in the actual working conditions. A Kinect sensor with the RULA method was primarily used to collect the data and evaluate the relevant postures. The results obtained were compared with the evaluation results by a human expert. Additionally, we verified the capability and effectiveness of this method. A program system for human joint recognition and acquisition was implemented. The results indicated that the Kinect joint data is generally accurate and can adequately complete the RULA evaluation table. The results from the front and right-hand side obtained by the Kinect were consistent with the results of the expert evaluation, and no significant difference was observed between them ($p>0.05$). However, when the participants faced the Kinect, the sensor performed better, and the evaluation result was more accurate. A high consistency was observed between the evaluation results obtained from the front and the expert (proportion agreement $\mathrm{\text{index}}=0.65$, Cohen’s $\mathrm{\text{kappa}}=0.77$). Only a slight consistency was observed between the evaluation results obtained from the right-hand side and the expert (proportion agreement $\mathrm{\text{index}}=0.41$, Cohen’s $\mathrm{\text{kappa}}=0.08$). This research created a new ergonomic method for the risk assessment of MSDs associated with sitting postures. The combination of theory and practice is crucial in the risk assessment of sitting postures in workplaces.

This work provides a foundation for a quantitative dynamical theory of heterochronic processes in the evolution of colonial invertebrate animals including Bryozoans, Siphonophores and Ants. These processes are environmentally induced changes in the time-sequencing of growth and development which can produce alterations in the morphotypes or castes within an individual colony. Motivation comes from Křivan’s theory of environmentally induced constraints on population densities for ecological interactions, but the present theory is second order with allometric production variables xⁱ and population densities for morphotypes, Nⁱ. We are able to unite ecological theory and the allometric form of the Wilson Ergonomic Theory via projective differential geometry and Wagner spaces which provide a natural description of environmentally induced time-sequencing changes altering the allometric curve of a species. Such changes define a model of heterochronic processes important in paleontology.

Background: The prevalence of musculoskeletal complaints in dentists is high although relatively few studies had focus in this profession. Various studies have been done to record stress levels and self-perceived health and health-related behaviors of dentists in other countries but limited data are available among the Indian dentists indicating the need to evaluate the same. Aim of this study was to find out the prevalence of lower quadrant dysfunctions among dentist and to investigate the risk factors for musculoskeletal complaints. Methodology: It was a cross-sectional study. A questionnaire interview was carried out among 85 dentists of Manipal, Karnataka, India. Questions include data on physical workload, perceived general health and the occurrence of musculoskeletal complaints pertaining to lower quadrant in the past 12 months, and various physical risk factors at the workplace. Statistical Analysis: Results were analyzed using descriptive statistics Results: Among all the area low-back pain (LBP) was the most prevalent musculoskeletal complaint, reported by 68% of the subjects followed by knee—35%, foot and heel—26%. Conclusions: Prevalence of Lower quadrant dysfunctions among dentist was 33%. The physical load, awkward posture and lack of physical activity among dentists seem to put them at risk for the occurrence of musculoskeletal disorders. Clinical Relevance: Identification of the risk factors may allow us to do a focused intervention in preventing these work-related musculoskeletal symptoms.

The anterior and posterior iliac spine markers frequently used to define the pelvis, are commonly occluded during three-dimensional (3D) motion capture. The occlusion of these markers leads to the use of various tracking marker configurations on the pelvis, which affect kinematic results. The purpose of this investigation was to examine the agreement of CODA pelvis kinematic results when two different tracking marker configurations were used during roofing tasks. 3D motion data were collected on seven male subjects while mimicking two roofing tasks. Hip joint angles (HJAs) were computed using the CODA pelvis with two different tracking marker configurations, the trochanter tracking method (TTM), and virtual pelvis tracking method (VPTM). Agreement between tracking marker configurations was assessed using cross-correlations, bivariate correlations, mean absolute differences (MADs), and Bland–Altman (BA) plots. The correlations displayed no time lag and strong agreement (all $r>0.83$) between the HJA from the VPTM and TTM, suggesting the timing occurrence of variables are comparable between the two tracking marker configurations. The MAD between the VPTM and TTM displayed magnitude differences, but most of the differences were within a clinically acceptable range. Caution should still be used when comparing kinematic results between various tracking marker configurations, as differences exist.

The need to develop objective functional muscle torque capability models has been a major concern for exercise scientists, rehabilitation therapists, as well as biomechanists and ergonomists, for many decades. This study provides a surface response normative database of 3-D dynamic torque capability profiles for the lower extremity knee and hip joints for twenty normal males and females. The results of the regression analyses were presented for each subject per direction of exertion for each joint depicting a wide range of adjusted R² values for each of the two joints (knee flexion: .26-.91, knee extension: .23-.80; hip flexion: .33-81, hip extension: .31-.80). Furthermore, the results showed that joint torque capability was significantly influenced by dynamic parameters such as the angular velocity, and that the interaction between angular position and velocity was highly significant. Such 3-D representation may be used as a "performance capacity envelope" to comprehensively characterize an individual's dynamic joint torque capability. Potential applications cover a broad spectrum ranging from rehabilitation to ergonomic and biomechanical applications and have significant implications in terms of guiding job assignment, return to work, as well as prognosis during the rehabilitation processes.

The objective of this study was to provide a normative database of dynamic upper-extremity (shoulder and elbow) joint strengths to fill the current void in literature for multidimensional strength capacity profiles. The isokinetic strength of the elbow and shoulder joints was tested for twenty normal males and females. The independent variables consisted of joint angular position, joint angular velocity, direction of exertion, and gender. The measured joint strength (torque, Nm) was the only defined dependent variable. The majority of existing joint strength prediction models and normative databases are static (isometric) in nature. The few available dynamic models are reported in the form of torque as a function of joint angle. Since joint strength is a function of both the joint angular position and angular velocity, descriptive models should take this interaction into consideration. The dynamic joint strengths of the subjects were studied using the KIN_COM 125E Plus. A second-order multiple regression analysis was used to model the dynamic 3-D strength surface response of each joint in each direction of exertion. Analysis of variance (ANOVA) with repeated measures design was used to test for the effects of gender, angular position, angular velocity, and direction on the dynamic strength of each joint, joint strength was significantly influenced by dynamic parameters such as the angular velocity. The interaction between angular position and velocity was highly significant. 3-D strength surface representation may be used as a "performance capacity envelope" to comprehensively characterize an individual's dynamic joint strength performance.

Besides causing a high mortality rate, the traditional method of releasing fish fry has a low level of safety and comfort. A new releasing device was thus designed based on ergonomic principles. The chute of this new releasing device reduced the mortality rate of fry, and the fish tank is also safer for the users to handle. The height of the releasing device and the door handle are both ergonomically designed, thereby helping to harmonize the interactions between man, the machine and the environment. This ultimately helps to realize the ideal of design being humanized and “people-oriented”.