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Biomedical subjects

Y Kurihara

Publications and source records attributed to Y Kurihara.

At least 235 records · Page 13Linked to original sources
PubMed1979

Frequency analysis of heart rate variability under flight conditions.

The factors causing heart rate variability (HRV) were investigated under various kinds of workloads and flight conditions. Frequency analysis of heart rate, and cross-correlation analysis with blood pressure and respiration, were performed by using the fast Fourier analyser. Consequently, the main frequency of HRV at rest consisted of 0.1 Hz and 0.25-0.3 Hz. These fluctuations disappeared under physical loads, but the value of 0.1 Hz at first increased under moderate mental load and thereafter decreased as the mental load increased. It was suggested that the behavior of the frequency 0.1 Hz under mental load was influenced partly by higher brain centers. For the actual flight, the frequency decreased under takeoff and landing, and remained as at rest during the gunnery and acrobatic training flight. It was concluded that the evaluation of workloads under flight conditions by using the analysis of the factors of HRV was very useful to improve a man-machine interface.

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PubMed1978

Maintenance of a certain rumen protozoal population in a continuous in vitro fermentation system.

A continuous culture system suitable for maintaining certain rumen protozoa was developed by modifying the procedure of Walter and Pilgrim (R.A. Weller and A.F. Pilgrim, Br. J. Nutr. 32:341-351, 1974) to include a dialyzing system. The concentration of ciliate protozoa, the pH value, and concentrations of volatile fatty acid and ammonia-N could be maintained within normal rumen limits for more than 15 days by appropriate choice of mechanical agitation and of the amount of substrate and physical form of the substrate bags. The average concentration of protozoa in the free fluid around the substrate was about 10% that in the fluid squeezed from solid digesta residues. More than 10(6) protozoa per ml was present in the fresh substrates only 2 h after supplying the substrate. These facts suggest that sequestration of the protozoa among particulate digesta is an important factor in maintaining the concentration of protozoa.

Animals↗
PubMed1978

Evaluation method of mental workload under flight conditions.

In order to analyze the relationship between heart rate variability (HRV) and the flight tasks of pilots, HRV of various mental and physical work stresses were investigated. For the physical stress on the treadmill, S.D. of heart rate sequence showed a minimum value at medium stresses and remained there until the maximum stress. However, the centrifuge acceleration test presupposed special physical stresses, and S.D. was almost same as the resting findings. In the tracking tasks, which presupposed maximum interpretative actions, the increase in the mean heart rate (MHR) was small with the S.D. increased a greater amount than for resting results. Consequently, preflight checks and level flight phases presupposed medium interpretative actions and mental stress with reserve capacity. Takeoff and landing phases were considered as both high interpretative action and high emotional stress situations. Acrobatic and gunnery training flight phases were considered physical load, strong interpretative actions, and emotional stress tasks.

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