Background Since the policy of “keeping trash off of the ground” in Taiwan, long-term exposure to repetitive motion in waste collection process results in high risk of upper extremity musculoskeletal disorders (UEMDs). Thus, we assessed the moderation and mediation effects of job-related stress and job support on work-related UEMDs among municipal waste collectors. Methods A cross-sectional study was conducted in two cities located at northern Taiwan during 2018–2019. 626 municipal waste collectors voluntarily participated and anonymously filled out a structured questionnaire. The moderation and mediation effects of effort-reward imbalance (ERI) and social support on UEMDs were analyzed by Haye’s Process Macro Model. Results Prevalence of UEMDs in municipal waste collectors were 43.4% for neck, 56.0% for shoulder, 24.1% for upper back, and 33.1% for hand/wrist. There was high prevalence of shoulder (72.2%), neck (48%), and upper back (30%) in female workers compared to male, most significantly in shoulders. In univariate and multivariate analysis, high ERI and low job support were significantly associated with ORs of 3.11 (95% CI:1.58–6.13) for elbow, 2.79 (95% CI:1.39–5.56) for shoulder, 3.39 (95% CI:1.64–7.00) for upper back and 3.83 (95% CI:1.98–7.41) for hand/wrist. Prevalent UEMDs were positively associated with high ERI in municipal waste collectors but negatively with job support. The moderation effects of ERI and job support on UEMDs, of which the measured synergy index exceeded one, were 18.24 for shoulder, 3.32 for elbow, and 2.45 for hand/wrist, but mediation effects were not significant. Conclusions This study found municipal waste collectors with work-related upper extremity disorders were significantly associated with work-related psychological risk factors. Therefore, waste collection cannot only to be improved by semi-automatic and automatic processes but immediate intervention programs for the reduction of psychological risk factors is needed promptly.
Despite repetitive activities and the frequency of high workload for municipal solid waste (MSW) collectors, the risks of work-related stress on upper extremity pain are inconclusive. The objective of this study is to assess the moderation and mediation effect of effort-reward imbalance (ERI) and over-commitment (OC) on upper back and hand/wrist disorders in MSW collectors. Methods: A cross-sectional study was conducted with MSW collectors from two cities in Taiwan. Each participant was asked to anonymously fill out a structured questionnaire. Work-related stress, including ERI and OC, was assessed by a Chinese version of the Job Content Questionnaire (C-JCL). Upper back and hand/wrist disorders were assessed using the Nordic musculoskeletal questionnaire. Multivariate analysis was used to assess moderation and mediation effect of OC and ERI on upper extremity pain. Results:The moderation effect of ERI and OC on upper back and hand/wrist disorders in MSW collectors was found. Disorders were higher in the group with both ERI ≥1 and high OC (OR (odds ratio) = 3.25 and OR = 3.00) than in the group with ERI ≥1 and low OC (OR = 2.66 and OR = 1.87) and in the ERI <1 and high OC group (OR = 2.27 and OR = 1.26). Synergy indexes were 0.77 and 1.77, respectively. Using multivariate analysis after adjusting for covariates, the mediation effect of OC was significant for the association between ERI and upper back and hand/wrist pains. The indirect effects of OC for upper back and hand/wrist pains accounted for 35% and 42%, respectively, and OC appears to mediate the relationship between ERI and upper back and hand/wrist disorders in MSW collectors. Conclusion: Work-related stress measured ERI and OC may play a role in moderating and mediating effects on upper extremity pain. Encouraging provisions of work modification and stress management is needed to mitigate the occurrence of upper extremities pain in MSW collectors.
Background TGF-β superfamily signaling is indispensable for bone homeostasis. However, the global expression profiles of all the genes that make up this signaling module in bone and bone-related diseases have not yet been well characterized. Methods Transcriptomic datasets from human bone marrows, bone marrow-derived mesenchymal stem cells (MSCs) and MSCs of primary osteoporotic patients were used for expression profile analyses. Protein treatments, gene quantification, reporter assay and signaling dissection in MSC lines were used to clarify the interactive regulations and feedback mechanisms between TGF-β superfamily ligands and antagonists. Ingenuity Pathway Analysis was used for network construction. Results We identified TGFB1 in the ligand group that carries out SMAD2/3 signaling and BMP8A, BMP8B and BMP2 in the ligand group that conducts SMAD1/5/8 signaling have relatively high expression levels in normal bone marrows and MSCs. Among 16 antagonist genes, the dominantly expressed TGF-β superfamily ligands induced only NOG, GREM1 and GREM2 via different SMAD pathways in MSCs. These induced antagonist proteins further showed distinct antagonisms to the treated ligands and thus would make up complicated negative feedback networks in bone. We further identified TGF-β superfamily signaling is enriched in MSCs of primary osteoporosis. Enhanced expression of the genes mediating TGF-β-mediated SMAD3 signaling and the genes encoding TGF-β superfamily antagonists served as significant features to osteoporosis. Conclusion Our data for the first time unveiled the transcription landscape of all the genes that make up TGF-β superfamily signaling module in bone. The feedback mechanisms and regulatory network prediction of antagonists provided novel hints to treat osteoporosis.
Work-related stress (WRS) is significantly associated with health-related quality of life (HRQoL), but the amounts of evidence on differences of effort-reward imbalance (ERI) and job strain index (JSI) remain sparse and have limited generalizability. Therefore, we aimed to assess the association between ERI and JSI with HRQoL and assess the mediation effect of social support (JS) and over-commitment (OC) on this association in Taiwan's civil servants. Material and Methods: A cross-sectional national survey was given to registered civil servants in Taiwan -20 046 civil servants from 647 institutions were enrolled using multistage stratified random cluster sampling. A web-questionnaire collected demographic in-
Ni-Cu-Zn ferrite components are very sensitive to stress and this can cause unstable permeability. This work focuses on the source of stress, and the interaction between the residual stress after sintering and the further stresses contributed by subsequent manufacturing processes of multilayer chip inductors. The results show that the sources of stress include cofiring of ferrite and silver coils, and the operations involved in the manufacturing processes. The results also show that the stresses pass through the interfaces between materials to the body of component and that the stresses induced in the subsequent manufacturing processes would accumulate or counteract with the residual stress in the component, although the stress can also be released by changing the connection status of these interfaces. The results also show that the compressive and tensile stresses cause different levels of inductance shift.
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