Masataka Nakabayashi

The effect of measurement position on brachial-ankle pulse wave velocity.

Arterial stiffness measurements are primarily used for the early detection of arteriosclerosis. Methods and devices that can easily measure arterial stiffness at home are in demand. We propose a simple method for measuring brachial-ankle pulse wave velocity (baPWV) at home using a reclining chair and investigate the effects of positioning on baPWV measurement. We measured baPWV in 50 healthy men (21-70 years) in seven different measurement positions, including the supine position, sitting, sitting with the knees flexed at 45°, sitting with the knees flexed at 0°, reclining at 37°, reclining at 50°, and standing. BaPWV was significantly lower in the supine position (P < 0.01) than in the other positions. It was significantly higher in the sitting position (P < 0.01) than in the reclining position (37°). No changes in baPWV were seen changing the knee flexion angle alone while sitting. Strong correlations were also ob- served between baPWV in the supine position and that in other positions. We showed that baPWV in the supine position can be calcu- lated by making corrections to baPWV measured in the sitting position at a reclining angle. Utilizing this corrected value would allow easy measurement at home using a reclining chair.

A novel propulsion mechanism using a fin with a variable-effective-length spring

Since the propulsion mechanism in fluid using an elastic fin, such as the caudal fin or the pectoral fin of fish, is effective. However, the optimum elasticity of the fin is not constant and changes with the movement task and environment. It is very difficult to exchange fins of different stiffness while the robot is swimming. Thus, we attempt to develop a variable-stiffness fin with a variable-effective-length spring. The apparent stiffness of this spring can be changed dynamically. The present paper describes the thrust force, and flow velocity corresponding to the self propelled speed of the fin in a uniform flow. And we compared the thrust efficiency in a uniform flow with the evaluating value of the thrust efficiency in a no flow. Furthermore, we developed a flow visualization system and discussed the flow-field around the fin in a uniform flow.

Bioinspired Aquatic Propulsion Mechanisms with Real-Time Variable Apparent Stiffness Fins

We aimed to develop the aquatic propulsion mechanisms of Paramecium like and fish like robots that consist of real-time variable stiffness fins. For the aquatic propulsion mechanisms of the Paramecium like robot, we have used fins with ICPF (Ionic Conducting Polymer gel Film) actuator to change its stiffness for representing ciliary movement. For the aquatic propulsion mechanisms of the fish like robot, we have used a fin with variable effective length spring which changes its apparent bending stiffness. We discussed the movement of the real-time variable stiffness fins and thrust force characteristics of the propulsion mechanisms in fluid.

Non-invasive Serum Cholesterol Detection Using Near-infrared Light Transmission

This paper investigated whether a simple, non-invasive blood vessel visualization technique using near-infrared light is suitable for determining serum cholesterol levels. Six-week-old male Wistar rats were divided into 6 groups (n = 10/group) and were fed either control diet alone or control diet with 0.5%, 1.0%, 1.25%, 1.5%, or 2.0% cholesterol for 8 weeks. A cuff was subsequently placed on the proximal part of the tail (cuff pressure, 80 mmHg), the tail distal to the compression site was exposed to near-infrared light (wavelength, 850 nm), and transmitted light was photographed. Near-infrared transmission images were acquired before and after cuff inflation, and hemoglobin and haematocrit levels in veins distal to the compression site were determined. Increased dietary cholesterol levels resulted in increased total serum cholesterol levels. Before cuff inflation, rats that were fed the 2.0% cholesterol diet had significantly lower hemoglobin levels than those that fed the control diet (P 150 mg/dL (r = 0.449, P 150 mg/dL, increased cholesterol levels affected erythrocyte membranes and probably reduced their deformability, resulting in decreased hemoglobin levels (anemia) with erythrocyte destruction in the spleen as the rate-determining factor. This decrease was detected as changes in near-infrared light transmission.

Thrust Force Characteristics of Propulsion Mechanism in Fluid Using Fin with Dynamic Variable-Effective-Length Spring

We aimed to develop a propulsion mechanism using a variablebending-stiffness fin of which stiffness can be changed dynamically. As the one such variable-stiffness fin, we have developed a fin with a variableeffective-length spring. The apparent bending stiffness of the fin can be changed dynamically. We have measured the thrust force of the propulsion mechanism using a fin with a variable-effective-length spring and visualized flow around the fin. In this paper, we describe the structure of the propulsion mechanism in fluid using a fin with a variable-effective-length spring, and the thrust force characteristics with changing effective length of the spring dynamically. Furthermore, we discuss the relationship between thrust force and flow around the fin.