Effects of anterior weight-shifting methods on sitting balance in wheelchair-dependent patients with spinal cord injury.

[Purpose] This study aimed to compare changes in the center of pressure between healthy subjects and patients with spinal cord injury and to provide basic information to these patients for improving their sitting balance. [Subjects and Methods] A total of 12 healthy subjects without histories of neurological or psychiatric disorders and 12 patients with spinal cord injuries were recruited. In all subjects, a change in the center of pressure during the performance of the modified functional reach test was measured using a Force Sensing Array system while the subjects were seated in a wheelchair. In the spinal cord injury group, the change in the center of pressure was highest when subjects reached forward while holding a gym ball. [Results] In the spinal cord injury group, the change in the center of pressure was highest when subjects reached forward while holding a gym ball. A significant correlation between forward reaching of the upper limbs with shoulders at 90° flexion and a change in the center of pressure was found. [Conclusion] Our findings suggest that the combination of functional reaching and the change in the center of pressure assessment is novel enough to be attempted to achieve sitting balance control in patients with spinal cord injury. The findings can provide clinical interventions that contribute to the improvement in the balance ability of wheelchair-dependent individuals.

The effects of upper and lower limb position on symmetry of vertical ground reaction force during sit-to-stand in chronic stroke subjects.

[Purpose] The purpose of this study was to evaluate the influence of arm and leg posture elements on symmetrical weight bearing during Sit to Stand tasks in chronic stroke patients. [Subjects and Methods] The subjects were diagnosed with stroke and 22 patients (15 males and 7 females) participated in this study. All participants performed Sit to Stand tasks on three foot postures and two arm postures. Two force plates were used to measure peak of vertical ground reaction force and symmetrical ratio to peak Fz. The data were analyzed using independent t-test and two-way repeated ANOVA. [Results] The results of this study are as follows: 1) Peak Fz placed more weight in non-paretic leg during Sit to Stand. 2) A symmetrical ratio to Peak Fz indicated significant difference between foot and arm posture, and had non-paretic limb supported on a step and paretic at ground level (STP) and grasped arm posture that lock fingers together with shoulder flexion by 90°(GA) (0.79 ± 0.09). [Conclusion] These results suggest that STP posture of the legs and GA posture of the arms should be able to increase the use of the paretic side during Sit to Stand behavior and induce normal Sit to Stand mechanism through the anterior tilt of the hip in clinical practices, by which loads onto the knee joint and the ankle joint can be reduced, and the trunk righting response can be promoted by making the back fully stretched. The outcome of this study is expected to be a reference for exercise or prognosis of Sit to Stand in stroke patients.

Comparison of vertebral and femoral bone mineral density in adult females.

[Purpose] This study assessed vertebral and femoral bone mineral density in adult females. [Subjects and Methods] A total of 314 females in their 40s to 70s were divided into normal, osteopenia, and osteoporosis groups and their vertebral and femoral bone mineral densities were compared. [Results] Comparisons of T scores revealed significant differences among measurements of the third lumbar vertebra, femoral neck, Ward's triangle, and femoral trochanter. Pearson correlation coefficients were used to assess differences between the vertebral and femoral measurements, and significant differences and positive correlations were observed among third lumbar vertebra, femoral neck, Ward's triangle, and femur trochanter in the normal group. [Conclusion] Females in the normal, osteopenia, and osteoporosis groups showed significant differences in their third lumbar vertebrae. The lack of significant differences among measurements in the osteoporosis group in this study suggests that patients with osteoporosis require careful and accurate diagnosis.

High-resolution field effect sensing of ferroelectric charges.

Nanoscale manipulation of surface charges and their imaging are essential for understanding local electronic behaviors of polar materials and advanced electronic devices. Electrostatic force microscopy and Kelvin probe force microscopy have been extensively used to probe and image local surface charges responsible for electrodynamics and transport phenomena. However, they rely on the weak electric force modulation of cantilever that limits both spatial and temporal resolutions. Here we present a field effect transistor embedded probe that can directly image surface charges on a length scale of 25 nm and a time scale of less than 125 µs. On the basis of the calculation of net surface charges in a 25 nm diameter ferroelectric domain, we could estimate the charge density resolution to be as low as 0.08 µC/cm(2), which is equivalent to 1/20 electron per nanometer square at room temperature.