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Effect of Oral γ-aminobutyric Acid (GABA) Administration on Sleep and its Absorption in Humans
Atsushi Yamatsu,Yusuke Yamashita,Tukaram Pandharipande,Isafumi Maru,김문조 한국식품과학회 2016 Food Science and Biotechnology Vol.25 No.2
The effects of γ-aminobutyric acid (GABA) on sleep and its levels in blood after oral administration were investigated in humans. A randomized, single-blind, placebo-controlled crossoverdesigned study was conducted to evaluate the effect of GABA on sleep. Sleep was evaluated by electroencephalography (EEG) after oral GABA administration. GABA significantly shortened sleep latency and increased the total non-rapid eye movement (non-REM) sleep time. Questionnaires showed that subjects receiving GABA realized its effects on sleep. In addition, the blood level of GABA after administration was investigated, and the absorption and metabolism rates of GABA were determined. GABA was quickly absorbed, and the blood level of GABA was the highest 30 min after oral administration, with a subsequent decrease in concentration. As GABA strongly affected the early stage of sleep, the effect of GABA on sleep may be connected to its levels in blood.
Suppression of Pressure Oscillation in Supersonic Parachute Model Using a Ring
Katsuyoshi Fukiba,Yuma Ueno,Yusuke Maru 한국항공우주학회 2024 International Journal of Aeronautical and Space Sc Vol.25 No.1
A method for suppressing the pressure oscillation of supersonic parachutes is proposed in this study. This method placed a ring with a triangular or circular cross section in front of the canopy of a parachute. A rigid metal canopy was used in supersonic wind tunnel tests. Hard piano wires with a diameter of 0.8 mm were used as suspension lines and a riser to connect a fore body and the canopy. In the wind tunnel test without a ring, pressure oscillation with the accompanying time variation of the shock wave structure was observed at Mach 3.0. A detached shock wave oscillated back and forth because it interfered with the boundary layer developed on the suspension lines. A large-amplitude pressure oscillation was observed with the pressure sensor placed at the center of the canopy. The large pressure oscillation was suppressed using a ring. The time variation of the shockwave structure suppressed. The amplitude of the pressure with the sensor reduced to 1/2 of that without a ring. We also found that the location and cross-sectional shape of the ring affects the flow around the canopy.
Study of Pressure Oscillations in Supersonic Parachute
Dahal, Nimesh,Fukiba, Katsuyoshi,Mizuta, Kazuki,Maru, Yusuke The Korean Society for Aeronautical Space Sciences 2018 International Journal of Aeronautical and Space Sc Vol.19 No.1
Supersonic parachutes are a critical element of planetary mission whose simple structure, light-weight characteristics together with high ratio of aerodynamic drag makes them the most suitable aerodynamic decelerators. The use of parachute in supersonic flow produces complex shock/shock and wake/shock interaction giving rise to dynamic pressure oscillations. The study of supersonic parachute is difficult, because parachute has very flexible structure which makes obtaining experimental pressure data difficult. In this study, a supersonic wind tunnel test using two rigid bodies is done. The wind tunnel test was done at Mach number 3 by varying the distance between the front and rear objects, and the distance of a bundle point which divides suspension lines and a riser. The analysis of Schlieren movies revealed shock wave oscillation which was repetitive and had large pressure variation. The pressure variation differed in each case of change in distance between the front and rear objects, and the change in distance between riser and the rear object. The causes of pressure oscillation are: interaction of wake caused by front object with the shock wave, fundamental harmonic vibration of suspension lines, interference between shock waves, and the boundary layer of suspension lines.
Study of Pressure Oscillations in Supersonic Parachute
Nimesh Dahal,Katsuyoshi Fukiba,Kazuki Mizuta,Yusuke Maru 한국항공우주학회 2018 International Journal of Aeronautical and Space Sc Vol.19 No.1
Supersonic parachutes are a critical element of planetarymission whose simple structure, light-weight characteristics together with high ratio of aerodynamic dragmakes themthemost suitable aerodynamic decelerators.The use of parachute in supersonic flow produces complex shock/shock and wake/shock interaction giving rise to dynamic pressure oscillations. The study of supersonic parachute is difficult, because parachute has very flexible structure which makes obtaining experimental pressure data difficult. In this study, a supersonic wind tunnel test using two rigid bodies is done. The wind tunnel test was done at Mach number 3 by varying the distance between the front and rear objects, and the distance of a bundle point which divides suspension lines and a riser. The analysis of Schlieren movies revealed shock wave oscillation which was repetitive and had large pressure variation. The pressure variation differed in each case of change in distance between the front and rear objects, and the change in distance between riser and the rear object. The causes of pressure oscillation are: interaction of wake caused by front object with the shock wave, fundamental harmonic vibration of suspension lines, interference between shock waves, and the boundary layer of suspension lines.