PubMed Health⌕ Search

Biomedical subjects

Makoto Yamauchi

Publications and source records attributed to Makoto Yamauchi.

7 recordsLinked to original sources

A new technique for harvesting costal cartilage with minimum sacrifice at the donor site.

With conventional procedures for harvesting costal cartilage, several large, full-thickness cartilage blocks are harvested from the chest wall and are cut, shaped, and joined to create the desired form. Many pieces of unused cartilage are discarded excluding those preserved for future use. Conventional procedures for costal cartilage harvesting are also associated with severe problems such as pain, deformity of the chest wall, and a long scar. We developed a new technique that permits only the necessary size and shape of cartilage to be directly harvested with the use of a chisel. With this technique, both sides and the bottom of the cartilage remain intact at the donor site. The anterior perichondrium can be harvested simultaneously. This technique was performed in 28 patients. The required quantities could be harvested in all patients without severe complications such as perforation of the pleura and excessive bleeding. The procedure required 30 min or less in all patients. The length of the skin incision was less than 3 cm in 25 patients and greater than 3 cm in two obese patients and a young man who had hard subcutaneous connective tissue. Pain intensity was markedly lower than that after conventional techniques. Twenty-six patients could walk 1 day after the operation. There were virtually no deformities of the thorax, even in children younger than 10 years. The structure of the reconstructed site was maintained during at least 2 years follow-up in all patients. Our technique for harvesting costal cartilage is associated with smaller scars, less pain, and less deformity of the chest wall than conventional procedures. In addition, it is minimally invasive and can be performed in a short time.

Adolescent↗

Dynamic evolution of the spectrum of long-period fiber Bragg gratings fabricated from hydrogen-loaded optical fiber by ultraviolet laser irradiation.

Long-period fiber Bragg gratings fabricated by exposure of hydrogen-loaded fiber to UV laser light exhibit large-scale dynamic evolution for approximately two weeks at room temperature. During this time two distinct features show up in their spectrum: a large upswing in wavelength and a substantial deepening of the transmission minimum. The dynamic evolution of the transmission spectrum is explained quantitatively by use of Malo's theory of UV-induced quenching [Electron. Lett. 30, 442 (1994)] followed by refilling of hydrogen in the fiber core and the theory of hydrogen diffusion in the fiber material. The amount of hydrogen quenched by the UV irradiation is 6% of the loaded hydrogen.

Journal Article↗

Thermal tuning of mechanically induced long-period fiber grating.

We have developed a wideband tunable optical filter that uses a long-period fiber grating (LPFG) in which both resonance wavelength and its signal attenuation can be adjusted. We create the grating mechanically by pressing a spring coil to an optical fiber. We achieve continuous fine tuning of wavelength and attenuation by varying the temperature of the LPFG. The adjustable ranges of the LPFG are more than 200 nm in resonance wavelength and more than 10 dB in signal attenuation.

Journal Article↗

Jones-matrix models for twisted-nematic liquid-crystal devices.

Twisted-nematic liquid-crystal devices having high spatial resolution are suitable for spatial light modulators. Phase-modulation characteristics of the devices have been widely studied, but the phase delay calculated using a conventional Jones-matrix model is slightly different from that measured using an interferometer. We propose a modified model whose matrix components are described by angular parameters that are related to the distribution of twist and tilt angles inside the liquid-crystal layer through differential equations. The model is used to simulate phase-modulation characteristics, and the result agrees well with the experimentally measured phase delay.

Journal Article↗

One-stage reconstruction of a large defect of the lower lip and oral commissure.

Large lower lip defects including the oral commissure are very difficult to reconstruct and obtain an aesthetic appearance and an acceptable function. We report two patients who had a large defect in the lower lip including oral commissure and were treated using free radial forearm flap and temporal muscle transfer in one-stage. For the cutaneous defects, in one a local flap was elevated from the adjacent cheek and in the other a turned over area of the forearm flap was used. In each case, the reconstructed lower lip could maintain adequate elevation of oral the commissure using the temporal muscle was worked. The first case which used a local flap externally could avoid sialorrhea and had good sensation, and could close the mouth firmly soon after surgery. The appearance was acceptable. In the other case, leakage of oral contact and air occurred at the oral commissure because of the thickness of the forearm flap but improved after minor correction some 8 months after the surgery.

Aged↗

Measurement of air turbulence for on-machine interferometry.

There is increasing demand for in situ shape measurements performed on ultraprecision processing machines. One major source of error during interferometric measurements performed on machines is fringe displacement due to external disturbances. We have developed an interferometer equipped with an electro-optic phase modulator that measures the phase of interference fringes before they are displaced by air turbulence. The frequency characteristics of air turbulence induced by a heat source are derived from successive measurements of a test surface. Experimental results show that the phase of the interference fringes can be accurately measured in the presence of air turbulence when the intensity of the fringes is sampled at a speed of several hundred hertz.

Journal Article↗