A model for developing job rotation schedules that eliminate sequential high workloads and minimize between-worker variability in cumulative daily workloads: Application to automotive assembly lines.

The aim of study is to suggest a job rotation schedule by developing a mathematical model in order to reduce cumulative workload from the successive use of the same body region. Workload assessment using rapid entire body assessment (REBA) was performed for the model in three automotive assembly lines of chassis, trim, and finishing to identify which body part exposed to relatively high workloads at workstations. The workloads were incorporated to the model to develop a job rotation schedule. The proposed schedules prevent the exposure to high workloads successively on the same body region and minimized between-worker variance in cumulative daily workload. Whereas some of workers were successively assigned to high workload workstation under no job rotation and serial job rotation. This model would help to reduce the potential for work-related musculoskeletal disorders (WMSDs) without additional cost for engineering work, although it may need more computational time and relative complex job rotation sequences.

Posttraumatic stress disorder associated with orthopaedic trauma: a study in patients with extremity fractures.

OBJECTIVE: The aims of this prospective study were to determine the prevalence of posttraumatic stress disorder (PTSD) in a population of young male military conscripts who experienced an extremity long-bone fracture, and to evaluate whether injury-related variables are associated with the development of PTSD. DESIGN: Prospective, nonrandomized comparative study. SETTING: Level 1 trauma center. PATIENTS AND METHODS: A total of 148 men (age older than 18 years) who had 1 or more acute long-bone extremity fractures within 12 months and were seen at the Seoul Regional Military Manpower Center for examination of military conscripts from March 2013 to March 2014, were enrolled. The Korean version of the posttraumatic disorder scale was used to identify aspects of PTSD. The injury-related variables assessed included injury mechanism, fracture location and multiplicity, fracture severity, and the occurrence of joint ankylosis and secondary osteoarthritis. RESULTS: Of the 148 participants, 40 (27.0%) met the criteria for the diagnosis of PTSD. Multivariate logistic linear analysis confirmed that lower extremity fracture, multiple fractures, and a higher pain visual analog scale score were significantly (P = 0.042, P = 0.043 and P < 0.001, respectively) related to the occurrence of PTSD. CONCLUSIONS: Lower extremity fracture, multiple extremity fractures, and higher pain visual analog scale scores were significantly related to the occurrence of PTSD. To achieve an optimal recovery after orthopaedic injury, clinicians must address both physical and psychologic needs of their patients. LEVEL OF EVIDENCE: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Deficient gaze pattern during virtual multiparty conversation in patients with schizophrenia.

Virtual reality has been used to measure abnormal social characteristics, particularly in one-to-one situations. In real life, however, conversations with multiple companions are common and more complicated than two-party conversations. In this study, we explored the features of social behaviors in patients with schizophrenia during virtual multiparty conversations. Twenty-three patients with schizophrenia and 22 healthy controls performed the virtual three-party conversation task, which included leading and aiding avatars, positive- and negative-emotion-laden situations, and listening and speaking phases. Patients showed a significant negative correlation in the listening phase between the amount of gaze on the between-avatar space and reasoning ability, and demonstrated increased gaze on the between-avatar space in the speaking phase that was uncorrelated with attentional ability. These results suggest that patients with schizophrenia have active avoidance of eye contact during three-party conversations. Virtual reality may provide a useful way to measure abnormal social characteristics during multiparty conversations in schizophrenia.

Chronic low back pain in young korean urban males: the life-time prevalence and its impact on health related quality of life.

OBJECTIVE: We assessed the life-time prevalence (LTP) of chronic low back pain (LBP) in young Korean males. We also evaluated the relationship between lumbar spinal lesions and their health related quality-of-life (HRQOL). METHODS: A cross-sectional, self-reported survey was conducted in Korean males (aged 19-year-old) who underwent physical examinations for the conscript. We examined 3331 examinees in November 2014. We included 2411 subjects, who accepted to participate this study without any comorbidities. We interviewed using simple binary questions for their LBP experience and chronicity. HRQOL was assessed by Short-Form Health-Survey-36 (SF-36) in chronic LBP and healthy control groups. Radiological assessment was performed in chronic LBP group to determine whether there were any pathological causes of their symptoms. RESULTS: The LTP of chronic LBP was 13.4%. Most (71.7%) of them didn't have any lumbar spinal lesions (i.e., non-specific chronic LBP). The SF-36 subscale and summary scores were significantly lower in subjects with chronic LBP. Between specific and non-specific chronic LBP group, all physical and mental subscale scores were significantly lower in specific chronic LBP group, except mental health (MH) subscale score. In MH subscale and mental component summary score, statistical significant differences didn't appear between two groups (p=0.154, 0.126). CONCLUSION: In Korean males 19 years of age, the LTP of chronic LBP was 13.4%, and more than two-thirds were non-specific chronic LBP. Chronic LBP had a significant impact on HRQOL. The presence of lumbar spinal pathoanatomical lesions affected mainly on the physical aspect of HRQOL. It influenced little on the mental health.

Involvement of the mirror neuron system in blunted affect in schizophrenia.

Blunted affect is a relatively enduring schizophrenic symptom and its presence brings about poor functioning and outcomes. Functional impairment in the mirror neuron system which is involved in both motor execution and imitation may be a neural basis of blunted affect, but it is not proved yet. Fifteen patients with schizophrenia and 16 healthy controls performed the facial expression task during functional magnetic resonance imaging. The task was to reproduce facial expressions in response to the face or word stimuli for happiness, sadness, and meaningless expression. Brain activities during facial expressions in patients compared with controls and their relationship with affective flattening were analyzed. Compared to controls, patients exhibited decreased activity in the widespread dorsal frontal regions and increased activity in the ventral frontal and subcortical regions. Patients also demonstrated significant negative correlation of the severity of affective flattening with activities in the mirror neuron system, such as the premotor cortex, motor cortex, and inferior parietal lobule. Emotional expression in patients with schizophrenia may be related to hypoactivity of the dorsal system and hyperactivity of the ventral system. An imbalance of these two systems may contribute to blunted affect. Directly addressing blunted affect using emotional expression provides a new perspective that functional disturbance of the mirror neuron system may play an important role in manifestation of blunted affect in schizophrenia.