Biomedical subjects

K Suizu

Publications and source records attributed to K Suizu.

4 recordsLinked to original sources

PubMed2006

Surface-emitted terahertz-wave generation by ridged periodically poled lithium niobate and enhancement by mixing of two terahertz waves.

Surface-emitted terahertz- (THz-) wave generation by difference-frequency mixing with ridge-shaped periodically poled lithium niobate (PPLN) was demonstrated. The PPLN had a ridge height of 300 microm, a thickness of 20 microm, and an interaction length of 35 mm. The ridge behaves as a slab waveguide for optical pump beams. The PPLN gives rise to THz waves in opposite directions, perpendicular to the pump-beam direction. Reflecting the THz wave on one side and overlapping it with the THz wave on the other side increased the total THz-wave intensity approximately 2.7 times compared with that without reflection and mixing.

Journal Article↗

PubMed2005

Assessment of room temperature influence on finger blood flow response induced by short-term grasping of vibrating handle.

OBJECTIVE: To investigate the influence of room temperature on finger blood flow (FBF) change in healthy subjects exposed to short-term grasping of a vibrating handle under different room temperatures. METHODS: FBF was measured using a blood flowmeter in six male subjects on the dorsum of the middle phalanx of third finger in both hands once at the end of every minute for an equal duration of 5 min at pre-exposure, during exposure to grasping of vibrating handle with sinusoidal vibration and after exposure. Vibration was generated with a frequency of 125 Hz and an rms acceleration of 40 m/s(2). Measurements were conducted in four room temperatures of 15+/-1, 20+/-1, 25+/-1 and 30+/-1 degrees C. RESULTS: Compared with the baseline measurements in the exposed hand during grasping of vibrating handle most significant increase in FBF was observed at 15+/-1 degrees C (P<0.001) and least at 30+/-1 degrees C (P<0.05), and after vibration least significant FBF was found at 25+/-1 degrees C (P<0.05). In case of the unexposed hand significant increase in FBF was exhibited at 20+/-1 degrees C (P<0.01) and 30+/-1 degrees C (P<0.01) during vibration, and only at 15+/-1 degrees C (P<0.05) after vibration. CONCLUSIONS: Response in FBF due to grasping of vibrating handle was of different patterns from the baseline measurement under different room temperature conditions in both exposed and unexposed hands and it was influenced by room temperature. Overall, the influence was greater at lower test room temperature, inducing more significant increase in FBF.

Adult↗

PubMed2005

Effects of waterproof covering on hand immersion tests using water at 10 degrees C, 12 degrees C and 15 degrees C for diagnosis of hand-arm vibration syndrome.

OBJECTIVES: To compare effects of waterproof covering on finger skin temperature (FST) and subjective hand pain during immersion tests using cold water at 10 degrees C, 12 degrees C and 15 degrees C. In the (Draft International Standard) of the International Organization for Standardization (ISO/DIS 14835-1), a water temperature of 12 degrees C and use of water covering are proposed. METHODS: Six healthy male subjects took part in the immersion tests and immersed both hands into water at 10 degrees C, 12 degrees C and 15 degrees C for 5 min, repeatedly, with waterproof covering (polyethylene gloves) or without (bare hands). The FST data from middle fingers and subjective pain scores for hand pain were analyzed. Furthermore, the test with water at 12 degrees C was repeated to assess the repeatability of the test. RESULTS: The glove and water temperature factors for FST were significant at every minute from 1 min during immersion up to 2 min after recovery, showing higher values for waterproof covering than for bare hands and showing lowest values for water temperature of 10 degrees C and highest for 15 degrees C. The glove and water temperature factors for subjective pain score were significant at the 1-min and 2-min points during immersion, showing lower scores for waterproof covering than for bare hands and showing highest scores for water temperature of 10 degrees C and lowest for 15 degrees C. The results of the first and second tests using water of 12 degrees C showed no systematic difference in FST and hand pain between the tests, with a few exceptions. CONCLUSIONS: Subjective pain during the cold immersion test with polyethylene gloves and water at 12 degrees C can be reduced, while the differences in FST between water temperatures of 10 degrees C and 12 degrees C were small or not apparent at some points during immersion and recovery. The test also seems to be suitable for repeatability. Further investigation on hand-arm vibration syndrome (HAVS) patients to validate the use of the immersion test with gloves to obtain sufficient data for diagnostic value is required.

Adult↗

PubMed2005

Terahertz generation with tandem seeded optical parametric generators.

A simple difference frequency generation (DFG) scheme based on two seeded optical parametric generators is presented as a tunable terahertz (THz) source. Using the nonlinear optical crystal 4-dimethylamino-N-methyl-4-stilbazolium-tosylate (DAST) as the DFG crystal, our system has demonstrated continuous and seamless tunable operation from 1.6 to 4.5 THz. The output bandwidth of the THz source is 2.4 GHz. The utility of the source over this spectral range is demonstrated by measuring a high-resolution transmission spectrum of water vapor in air.

Journal Article↗