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Bi-directional free-space optical communication with bidirectional 2x4x10 Gb/s wavelength division multiplexing channel signals is demonstrated. The environmental factor effects including thermally induced non-uniform air index and rainfall on the FSO performance are investigated.

It has been thought that imbalance in the jaws can cause loss in arm strength. In this study, EMG will be used to determine the EMG–Force relationship of the jaw, neck and arms muscles. This will give us useful insights on the arms strength loss due to the biomechanical effects of the imbalance in the jaw mechanism. Three male subjects (average age: 20.67±2.89 years old) participated in this investigation. The subject were asked to stand with their arms and legs extended in frontal plan in such a way that the ratio subject intra-feet distance/ subject height equal 0.25. The experimental protocol consisted of two paradigms that (1) From the initial position (0 mm, 5 kg), external loading weight was added incrementally (6kg, 7kg) until the subject can hold the weight in 10 seconds. Check EMG signal quality and data storage; (2) Perform variation in spacer thickness from 2mm to 3mm and execute step 1 for each variation. Myoelectric signals of the masseter, trapezoid, deltoid and brachiodiolis muscles were measured. Higuchi fractal dimension was used to analyze the complexity of surface EMG signal of these four muscles. The results showed that (1) The activities of arm muscles varied according to the applied pull-down force; (2) The masseter, trapezoid and deltoid muscles displayed the greatest amount of activity in this study. There was also a significant difference in the fractal dimension values of the surface EMG signal before and after the loss of arm strength.

It has been reported that imbalance in the jaw can cause loss in arm strength. In order to investigate this phenomenon based on the relationship between bite and neuron activities, Near-infrared spectroscopy (NIRS) was used. The purpose of this study was to determine the influence of biting on the concentrations of oxygenated hemoglobin on the motor area. NIRS was administered for three healthy subjects. Subjects were asked to perform 3 different tasks: biting on a spacer using the right jaw, lifting up a weight with the right arm, and combining the two. The NIRS probes were positioned contralaterally, in the left region. The results suggested that using jaw muscles and arm muscles influenced the neuron activities in the motor area. Moreover, the neuron activities increased significantly when the arm muscles were used instead of the jaw muscles, as shown by levels of OxyHemoglobin in the motor area.

It has been thought that imbalance in the jaws may cause loss in arm strength. However to the best of our knowledge there has been no study on this topic. In this pilot study we quantified this phenomenon. A pool of 34 healthy subjects (ages from 19 to 21 years old; average age: 19.8±0.9 years old) participated in this study. They were randomly selected to participate in different experimental paradigms. Most of them were naive to the study. All signed the consent forms. The subjects were asked to stand straight and extend their arms and legs in frontal plan. The ratio of the distance between the 2 feet and their heights was the same to all subjects and equal to 0.25. The goal of this investigation was to record the maximum forces that the subjects can resist against a pull-down force on their hands while biting a spacer of adjustable height in the left or right or both sides of their jaws or using the incisors. The control group consisted of data obtained without using spacer and on the other side of the arm. The experimental protocol consisted of several paradigms. The order of executing the paradigms was random. The results showed that (1) Imbalance bite induces contralateral loss of arm strength; (2) The loss is approximately a linear function of the height of the spacers; (3) The loss leveled when the spacer was higher than 2mm; (4) The slopes of the linear function were similar in both arms and independent to the gender; and (5) The arm strength of male was higher than that of female subjects. This investigation may be interesting in sport medicine to study the effects of the mouth guards on the athlete arm strength.