Mental health and current issues of migrant workers in Japan: A cross-sectional study of Vietnamese workers.

BACKGROUND: Over the past 5 years, the number of Vietnamese migrant workers in Japan has grown rapidly to become the largest group of migrant workers in the country. They hold various statuses of residence and are subjected to multifactorial stressors. AIMS: The current study's aim is to investigate the association between psychological distress experienced by Vietnamese workers and their work environment. Another aim is to discuss issues involving migrant workers by comparing the characteristics of workers in the major statuses of residence. METHODS: The study applied a cross-sectional design, and included a nationwide self-administered online questionnaire that was conducted in Vietnamese in 2022. The questionnaire included the Kessler Psychological Distress Scale (K10), workplace interpersonal factors as well as factors related to work and health. A multiple logistic regression analysis was conducted to investigate factors associated with psychological distress. RESULTS: Of 933 Vietnamese workers, 37% were grouped as distressed under the K10 cutoff. Fewer opportunities to speak with Japanese co-workers, lower welfare and workload ratings, and the visa statuses including 'Technical Intern Training' were significantly associated with psychological distress. Unexpectedly, those in 'Engineer/Specialist in Humanities/International Services (ESI)' category who are deemed to hold better conditions demonstrated the highest amounts of distress. CONCLUSION: Outside of unsatisfactory working environments, differing situations depending on status of residence could produce various sources of distress. The difficult aspects of Japan's distinct culture seem to contribute to their distress, especially for those who have more interactions with Japanese co-workers. A push for a multicultural society, where migrant workers can pursue proactive life designs of their own choosing, is warranted.

Burn and cut injuries related to job stress among kitchen workers in Japan.

To clarify the correlation between kitchen work-related burns and cuts and job stress, a self-administered questionnaire survey was conducted involving 991 kitchen workers among 126 kitchen facilities. The demographics, condition of burns and cuts, job stress with the Brief Job Stress Questionnaire (BJSQ), health condition, and work-related and environmental factors were surveyed. Multiple logistic regression models and trend tests were used according to quartiles (Q1, Q2, Q3, and Q4) of each sub-scale BJSQ. After adjustment for potential confounding variables, burns/cuts were associated with a higher score category (Q4) of job demands (OR: 2.56, 95% CI: 1.10-6.02/OR: 2.72, 95% CI: 1.30-5.69), psychological stress (OR: 4.49, 95% CI: 2.05-9.81/OR: 3.52, 95% CI: 1.84-6.72), and physical stress (OR: 2.41, 95% CI: 1.20-4.98/OR 2.16, 95% CI: 1.16-4.01). The ORs of the burn/cut injures increased from Q1 to Q4 with job demands (p for trend = 0.045/0.003), psychological stress (p for trend<0.001/0.001), and physical stress (p for trend = 0.006/0.005), respectively. These findings suggest that kitchen work-related burns and cuts are more likely to be correlated with job stress, and the higher the job stress score, the higher the frequency of burns and cuts among kitchen workers.

Risk factors for frequent work-related burn and cut injuries and low back pain among commercial kitchen workers in Japan.

This study investigated risk factors for frequent work-related burn and cut injuries and low back pain (LBP) among kitchen workers including personal, work-related and environmental factors. Subjects were 991 kitchen workers in 103 schools, 17 hospitals and nursing homes, and 6 restaurants in central Japan. A cross-sectional survey was carried out using a structured self-administered questionnaire. Logistic regression models were used to examine associations between frequent injuries/LBP and risk factors. The effective response rate was 75.1% (n=744), the mean age was 40.7 (SD 11.7) and 77.2% were female. Burn injury was associated with a smaller kitchen (OR 1.94; 95%CI, 1.13-3.33), and gas kitchens rather than electric kitchens (OR 2.30; 95%CI, 1.17-4.52). LBP was associated with female gender (OR 2.46; 95%CI, 1.37-4.43), high body height (>160 cm) (OR 2.03; 95%CI, 1.22-3.36), and large number of meals produced per person (≥ 150 meals) (OR 1.83; 95%CI, 1.12-3.00). The results of this study suggest that securing adequate work space and introducing electric kitchen systems may reduce the risk to kitchen workers, as well as the importance of adequate height of cooking equipment and selecting an appropriate volume of meals to produce per person to prevent LBP in kitchen workers.

Coherent optical MIMO transmission over 20 km GI multi-mode fiber by using digital coherent receiver with mode convergence unit.

We describe a coherent optical MIMO transmission experiment that employs a digital coherent receiver with a mode convergence unit, which converges higher-order mode light into the fundamental mode while maintaining the phase and amplitude information of the higher-order mode. The coherent optical MIMO transmission of two 10 Gbit/s BPSK signals over 20 km of graded-index multi-mode fiber was successfully achieved by using this mode convergence unit. We also show numerically that multi channel signals for a coherent optical MIMO transmission can be recovered by employing sufficient mode diversity, even if mode conversion occurs in the transmission fiber.

The effects of work environments on thermal strain on workers in commercial kitchens.

The purpose of this study was to clarify the effect of working environments of different kinds of commercial kitchens on the thermal strain of kitchen workers. This study design was cross-sectional study, and data collection was performed during busy time in commercial kitchen from August to September 2006. The research subjects were 8 institutions, involving 7 cookers, and 16 men. Measured environmental variables were air temperature, radiant heat index, wet bulb globe thermometer index (WBGT) in front of the cookers, ambient temperature, and estimated ambient WBGT around the workers. The thermal strain on workers was evaluated by fluid loss, body temperatures, heart rate and amount of physical activity (METs). All average estimated ambient WBGTs in front of cookers were less than 27.5℃. The average heart rate was 107 ± 10 bpm, and average METs was 2.0 ± 0.6. The peak values of upper arm skin temperature and auditory canal temperature were less than 37.5℃. The work environments were affected by the kitchen spaces, cooling devices, heating methods, and heat sources. Even in the midsummer, if environmental temperatures were controlled adequately, estimated ambient WBGTs around workers were below the occupational exposure limit. Work environments and thermal strain on workers in commercial kitchen were not severe.

Hole-assisted dual concentric core fiber with ultralarge negative dispersion coefficient of -13,200 ps/nm/km.

We propose a dual concentric core fiber (DCCF) with six homogeneous air holes, designed to realize a large negative dispersion coefficient. We clarify numerically that the dispersion property of the proposed DCCF can be controlled flexibly by adjusting the air-hole structure, and we realize the largest reported negative dispersion of -13,200 ps/nm/km experimentally.

Prevalence of self-reported finger deformations and occupational risk factors among professional cooks: a cross-sectional study.

BACKGROUND: Previous studies have pointed out that the school lunch workers in Japan are suffering from work-related disorders including finger deformations. The purpose of this study was to investigate the prevalence of self-reported finger deformations and the association with job-related risk factors. METHODS: A cross-sectional questionnaire study of 5,719 subjects (response rate: 81%, 982 men and 4,737 women) was undertaken during September 2003 to February 2004. RESULTS: Finger deformations were found among 11.7% of the men and 35.6% of the women studied, with significant differences among sex, age and sex-age groups. For both men and women the pattern of finger deformations across the hand was similar for the right and the left hand. For women, the deformations were found in about 10% of the distal interphalangeal joints of all fingers. Based on multiple logistic regression analyses, the factors female sex, age, the number of cooked lunches per cook and cooking activities were independently associated with the prevalence of finger deformations. High prevalence odds ratios were found for those frequently carrying or using tools by hands such as delivering containers, distributing meals, preparing dishes, washing equipment, cutting and stirring foods. CONCLUSIONS: Among the school lunch workers studied, women had a higher prevalence of finger deformations on all joints of both hands. Various cooking tasks were associated with the prevalence of finger deformations. The results suggest that improvements in working conditions are important for preventing work-related disorders such as finger deformations.

Transmission over large-core few-mode photonic crystal fiber using distance-independent modal dispersion compensation technique.

We propose a transmission distance-independent technique for modal dispersion compensation over few-mode fiber that uses a single-input multiple-output configuration and adaptive equalization. Our technique can compensate for the modal dispersion of a signal with 1-tap FIR filters regardless of the amount of modal delay difference, and enables us to utilize fiber with a large core and few modes as a long-haul transmission line. We also show numerically the advantage of few-mode photonic crystal fiber (PCF) for realizing a larger effective area (A(eff)), and finally we report a transmission over a large-core two-mode PCF with A(eff)>280 µm(2).

Group velocity dispersion measurement method using sinusoidally phase-modulated continuous wave light based on cyclic nature of optical waveform change by group velocity dispersion.

We show that any optical pulse train recovers its original waveform after passing through a group velocity dispersion (GVD) device when the total GVD value of the device is equal to an integral multiple of 1/(2πf(rep)(2)), where f(rep) is the repetition rate of the optical pulse train. In addition, we detail our proposed GVD measurement method, or optical phase-modulation (PM) method, which utilizes a sinusoidally PM continuous wave (CW) light as a probe light. The total GVD B(2) of a device under test (DUT) is derived by using a very simple equation, |B(2)|=1/(2πf(null)(2)), where f(null) is the smallest modulation frequency at which the sinusoidally PM light becomes CW light again after passing through the DUT.

Prevalence and risk factors of low back pain among Thai and Myanmar migrant seafood processing factory workers in Samut Sakorn Province, Thailand.

This study assessed the prevalence of low back pain (LBP) and investigated risk factors for LBP among seafood processing factory workers in Thailand including migrant workers. The subjects were Thai and Myanmar workers in the typical seafood processing factory. A cross-sectional study was carried out with a self-administered questionnaire. Prevalence of LBP, general characteristics, life style, and working condition were investigated. The associations between LBP and risk factors were estimated by multiple logistic regression models. Of 254 workers, 165 completed the questionnaire. Half of these workers were Thai, the others were from Myanmar. The point prevalence of LBP was 28.5%. Risk factors for LBP were age over 40 yr, poor health status, history of back injury, twisting posture at work, and slipping on wet floors. The results suggest that health promotion should focus on working conditions rather than individual life style in order to prevent LBP. Furthermore, greater attention to other risk factors such as history of back injury and perception of health status after regular health check up, especially in older age groups may be needed.

Observation of a propagation mode of a fiber fuse with a long-period damage track in hole-assisted fiber.

We examined the fiber-fuse propagation characteristics in hole-assisted fibers (HAFs) when the diameter of an inscribed circle linking the air holes was almost the same as the diameter of the melted area caused by the fiber fuse. We observed a new propagation mode for the fiber fuse in HAF with a damage track whose period was approximately 30 times longer than that in conventional single-mode fiber. We also made the first observation of a new threshold power (upper threshold) for the fiber fuse.

Evaluation of subjective thermal strain in different kitchen working environments using subjective judgment scales.

To elucidate the subjective thermal strain of workers in kitchen working environments, we performed a cross-sectional study involving 991 workers in 126 kitchen facilities in Japan, using a self-reporting questionnaire survey and subjective judgment scales (SJS). The ambient temperature, mean radiant temperature (MRT), and wet-bulb globe temperature (WBGT) index were measured in 10 kitchen facilities of the 126 kitchens. The association of SJS with the types of kitchen was estimated by multiple logistic regression models. Of the 991 kitchen workers, 809 (81%) responded to the questionnaire survey. Compared with the electric kitchens, the proportion of workers who perceived the room temperature as hot to very hot was significantly higher, and the ambient temperature, MRT, and WBGT were significantly higher in the gas kitchens. Compared with the electric kitchens, workers in gas kitchens had a more than fivefold (males) and tenfold (females) higher SJS adjusted for confounding factors (male odds ratio (OR), 5.13; 95% confidence interval (CI), 1.65-15.9; and female OR, 10.9; 95%CI, 3.89-30.5). Although SJS was affected by some confounding factors, our results suggest that workers in gas kitchens might be exposed to a higher heat strains than those in electric kitchens.

Layer-by-layer assembled thin films composed of carboxyl-terminated poly(amidoamine) dendrimer as a pH-sensitive nano-device.

Dendrimer-containing multilayer thin films have successfully been prepared by a layer-by-layer deposition of carboxyl-terminated poly(amidoamine) dendrimer (PAMAM-COOH) and poly(methacrylic acid) (PMA) on a solid surface at pH 4.0, while the multilayer film did not form at pH 7.0. The PMA/PAMAM-COOH multilayer films prepared at pH 4.0 are decomposed at neutral pH due to electrostatic repulsion between negatively-charged carboxylate residues. The results suggest that the primary force for the successful deposition of PAMAM-COOH and PMA at pH 4.0 is hydrogen bonding between COOH residues on the surface of the dendrimer and PMA. The multilayer films are decomposed also at strongly acidic pH, suggesting an electrostatic force of attraction between the protonated tertiary amino groups in PAMAM-COOH and a small fraction of COO(-) residues in PMA contributes in part to the multilayer formation at pH 4.0. The PMA/PAMAM-COOH thin films can accommodate model dyes, Rose Bengal and 5,10,15,20-tetraphenyl-21H,23H-porphinetetrasulfonate, and the release can be controlled by changing pH.

Prevalence and risk factors for low back pain among professional cooks working in school lunch services.

BACKGROUND: The prevalence of self-reported low back pain among professional cooks was estimated to examine the effects of daily life conditions, job-related factors, and psychological factors on this disorder. METHODS: Data was collected using a mailed self-administered questionnaire. RESULTS: Of 7100 cooks, 5835 (82%) replied to the questionnaire, including 1010 men and 4825 women. The mean age was 41.4 for men and 47.5 for women. The prevalence of low back pain during a 1-month period was 72.2% among men and 74.7% among women, with no significant differences between groups. By logistic regression analyses, factors significantly associated with the prevalence of low back pain in 1 month were female gender (prevalence ratio [PR] 1.32; 95% CI, 1.03-1.68), current smoking (PR 1.57; 95% CI, 1.24-1.98), and past smoking (PR 1.35; 95% CI, 1.01-1.79). As for job-related factors, the number of cooked lunches per person (PR 1.28; 95% CI, 1.05-1.56), breaks in the morning session (PR 1.33; 95% CI, 1.13-1.56), kitchen environment (PR 1.09; 95%, CI, 1.03-1.15), and height of cooking equipment (PR 1.13; 95% CI, 1.08-1.19) were associated with the prevalence of low back pain. As for psychological factors, job satisfaction (PR 1.22; 95% CI, 1.03-1.45), stress at work (PR 1.68; 95% CI, 1.42-1.99), financial constraints (PR 1.23; 95% CI, 1.03-1.47), health-related stress (PR 1.31; 95% CI, 1.08-1.59) and worries about the future (PR 1.24; 95% CI, 1.01-1.52) were similarly associated. CONCLUSION: Daily life conditions, job-related factors, and psychological factors are associated with the occurrence of low back pain. It is important to take comprehensive preventive measures to address a range of work and life conditions that can be improved to decrease the incidence of low back pain for professional cooks.