Inputs from the visual, somatosensory and vestibular systems must be integrated efficiently to activate appropriate motor responses in maintaining optimal balance. This study examined the standing balance of 17 children (7 to 10 years old) and 17 young adults (19 to 23 years old) as a function of sensory organization, sensory system efficiency, and postural strategy adopted. Tests of standing balance were administered under six sensory conditions created by simultaneous alteration of the visual (full, occluded, or sway-referenced) and the somatosensory inputs (fixed-foot or compliant-foot support). The sway area and the sway amplitude of the center of pressure were measured and analyzed. Three findings are notable. The function of sensory organization for balance control was poorer for the children than the young adults. The functional efficiency of the somatosensory and the visual systems of children have developed to the young adult level, but that of the vestibular system has not. There was no difference between children and young adults in hip control, but there was in ankle control when the vestibular input was the only reliable source of sensory input. These results suggest that the functional efficiency of the vestibular system in children 7 to 10 years of age may still be developing. This may account for their poorer function of sensory organization and lower performance of standing balance.

Electrical stimulation is usually applied percutaneously for facilitating peripheral nerve regeneration. However, few studies have conducted long-term monitoring of the condition of nerve regeneration. This study implements an implantable biomicrosystem for inducing pulse current for aiding nerve repair and monitoring the time-course changes of nerve impedance for assessing nerve regeneration in sciatic nerve injury rat model. For long-term implantation, a transcutaneous magnetic coupling technique is adopted for power and data transmission. For in vivo study, the implanted module was placed in the rat's abdomen and the cuff electrode was wrapped around an 8-mm sciatic nerve gap of the rat for nerve impedance measurement for 42 days. One group of animals received monophasic constant current via the cuff electrode and a second group had no stimulation between days 8-21. The nerve impedance increased to above 150% of the initial value in the nerve regeneration groups with and without stimulation whereas the group with no nerve regeneration increased to only 113% at day 42. The impedance increase in nerve regeneration groups can be observed before evident functional recovery. Also, the nerve regeneration group that received electrical stimulation had relatively higher myelinated fiber density than that of no stimulation group, 20686 versus 11417 fiber/mm (2). The developed implantable biomicrosystem is proven to be a useful experimental tool for long-term stimulation in aiding nerve fiber growth as well as impedance assessment for understanding the time-course changes of nerve regeneration.

The structural properties of nitride‐based light‐emitting diodes (LEDs) grown on micro‐ and nano‐scale patterned sapphire substrates (PSS) were discussed in detail. The high resolution X‐ray diffraction (HRXRD) and etch‐pit density (EPD) results reveal that the crystalline quality of the epitaxial GaN film could be effectively improved by using the PSS technique, and depended on the aspect ratio of PSS. The crystalline quality of epitaxial GaN films grown on PSS‐2μm and PSS‐3μm was better than that of the LED grown on NPSS. The electrical characteristics and junction temperature results of the LED grown on micro‐scale PSS were better compared with nano‐scale PSS. But the output power of the LED grown on nano‐scale PSS was larger than that of the LED grown on micro‐scale PSS since the pattern‐size of PSS is related to the capability of light extraction. However, when the spacing of PSS is less than 2 μm, some voids formed at the GaN/sapphire interface may cause the thermal dissipation problem of LEDs. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Functional decline of lower-limb affects the ability of locomotion and the age-related brain differences have been elucidated among the elderly. Cycling exercise is a common training program for restoring motor function in the deconditioned elderly or stroke patients. The provision of speed feedback has been commonly suggested to clinical therapists for facilitating learning of controlled cycling performance and maintaining motivation in training programs with elderly participants. However, the cortical control of pedaling movements and the effect of external feedback remain poorly understanding. This study investigated the regional cortical activities detected by functional near infrared spectroscopy (fNIRS) in 12 healthy young and 13 healthy elderly subjects under conditions of cycling without-(free cycling) and with feedback (target cycling). The elderly exhibited predominant activation of the sensorimotor cortex during free cycling similar to young subjects but with poorer cycling performance. The cycling performance improved in both groups, and the elderly showed increased brain activities of the supplementary motor area and premotor cortex under target cycling condition. These findings demonstrated age-related changes in the cortical control in processing external feedback and pedaling movements. Use of fNIRS to evaluate brain activation patterns after training may facilitate brain-based design of tailored therapeutic rehabilitation strategies.