In the last few years, epidemiological studies have shown correlations between the low endurance capacity of the erector spinae muscle and low back pain (LBP). In this study, the function of the erector spinae muscle and localized muscle fatigue in LBP were investigated in both LBP patients and control subjects without LBP, using surface multi-channel electromyograms (EMG). Four positions (L1, L2, L4, L5) were chosen as representative locations for the different functions of the erector spinae muscle. Median frequency (fm) parameters of an EMG power density spectrum were monitored to quantify localized muscle fatigue. This research indicated a statistically significant difference (P < 0.05) in fm parameters between the LBP patients and the control subjects. The integrated electromyogram (iEMG) signals of LBP patients were considerably higher than for the control subjects during endurance isometric contraction. Our research suggested that human fatiguing erector spinae muscle, in submaximal voluntary contractions tests, induced a different firing order of motor unit spikes between two groups.

Radio on Free Space Optics (RoFSO) is being developed to realize a cost effective and universal platform for heterogeneous wireless services as same as RoF. The developed RoFSO transceiver can directly transmit some RoF signals from an optical fiber and can receive an RoFSO signal from air into a fiber core. It can achieve an free space that is transparent for various types of wireless services in an optical wireless beam. This paper describes the features of developed equipments, and propose the link budget design for WLAN and terrestrial digital broadcasting services.

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