Yuji Hirao

Evolvable Hardware and Its Applications to Pattern Recognition and Fault-Tolerant Systems

This paper describes Evolvable Hardware (EHW) and its applications to pattern recognition and fault-torelant systems. EHW can change its own hardware structure to adapt to the environment whenever environmental changes (including hardware malfunction) occur. EHW is implemented on a PLD(Programmable Logic Device)-like device whose architecture can be altered by re-programming the architecture bits. Through genetic algorithms, EHW finds the architecture bits which adapt best to the environment, and changes its hardware structure accordingly.

Synchronized measurements of blood flow velocity distributions in carotid, brachial and femoral arteries, and ECG in human during exercise

A measurement system was developed, which was able to measure synchronously blood flow velocity distributions and ECG during exercise. It was found from the results of experiments that the slower maximum blood flow velocity and the faster wave propagation time were observed for standing posture as compared with those for supine. Similarly, it was found that these became faster in proportion to work rate during walking on a treadmill.

Monitoring Carotid Blood Flow and ECG for Cardiovascular Disease in Elder Subjects

This report is to investigate the correlation between common carotid blood flow (CCBF) properties and the risk factors for cardiovascular disease. The measurement system was designed for simultaneously monitoring of CCBF and electrocardiogram (ECG) in order to get more valid information for detection and diagnosis of cardiovascular disease. In our study, blood flow velocimeter was developed to measure blood flow in carotid by using ultrasound Doppler technique. This measurement system is based on a continuous-wave (CW) Doppler ultrasound method with two semicircular piezoelectric (PZT) transducers, one continuously transmitting ultrasound, and the other continuously receiving the echoes. Eleven patients with cardiovascular disease underwent in the experiment. In the report, blood flow was compared with data from 25 healthy subjects which asymptomatic subjects putatively free of cardiovascular disease as controls. The maximum of CCBF velocity was 102.8 (SD 18.3) cm/s in the 25 healthy subjects. While, the maximum of CCBF velocities were 53.9 (SD 16.6) cm/s in the eleven cardiac patients. The data suggest that CCBF velocity decreased significantly in the cardiac patients and by simultaneously monitoring of CCBF and ECG were probably obtained more valid information to detect and diagnose cardiovascular disease at the early stage

Blood Flow Velocities in Common Carotid Artery Changes with Age and Exercise Study by using of telemetry method

Measurement of blood flow velocity using Doppler ultrasound has become an important noninvasive tool not only in the diagnosis of cardiovascular disease but also in physiological measurement. Physiological blood flow velocities in common carotid artery (CCA) is altered markedly with advancing age. It is unknown that regular aerobic exercise training can alter and improve blood flow velocity waveforms in either healthy young or healthy older individuals. Blood flow velocities were measured in 89 putatively healthy volunteers with age range of 20-76 years: 65 subjects were sedentary and 24 subjects were regular exercise-trained. Blood flow velocity spectra were measured at resting using our newly developed portable telemetry Doppler ultrasound velocimeter (TDUV) with real-time monitoring. Blood flow velocity waveforms were obtained from the spectral blood flow velocities of instantaneous peak-velocities. As a result, blood flow in peak systolic SI, end-diastolic d, and peak diastolic velocities D decreased with aging by the following yearly rate: 7.18 mm/s/year, 2.64 mm/s/year, and 1.24 mm/s/year, respectively. Thus the indices of d/S1, S1/S2, and D/I had a significant change with age. However, resting heart rate (HR) and second systolic velocities S2 were not significantly changed with aging. Blood flow velocities in SI were higher in the exercise-trained, whereas S2, D, and d velocities had no difference between trained and sedentary adults. However, the index of D/I had a marked higher in exercise-trained adults. As anticipated to exercise effect, the resting heart rate (HR) were significantly lower in exercise-trained. There were no differential effects in three age-groups (P= NS, by multivariate analysis). In conclusion, an age-associated decrease blood flow velocities in CCA was altered and improved in the healthy middle-aged and older individuals who regularly performed aerobic exercise. The blood flow patterns in three age-groups design had no markedly change with age in regular aerobic exercise-trained adults. The adaptations of blood flow velocities to regular exercise were not different with aging.

Effects of Aging and Exercise Training on the Common Carotid Blood Velocities in Healthy Men

An age-related alteration in the cardiovascular response to exercise training are evident. The purpose of the study was to investigate the effects of exercise and age on blood velocities in common carotid artery in 82 healthy men between the age ranges of 21 to 67 years old. Blood velocities are characterized to five components of velocity waveforms as peak systolic (SI), second systolic (S2), incisure between systole and diastole (I), peak diastolic (D) and end-diastolic velocity wave (d). Decrease of blood velocities in peak systolic (r=-0.711, P< 0.0001) and in peak diastolic velocities (r=-0.521, P< 0.0001) with aging are improved and partially restore in particularly older men. The velocity ratio of S2/S2-1 as a reflection index increase with age (r= 0.797, P< 0.0001), however is smaller in exercise-trained older compared with sedentary peers. The ratio of 1-I/D as a vascular elastic recoil index decrease with aging (r=-0.640, P<0.0001), but is relatively higher in exercise-trained men. Exercise training improves the age-related deterioration in blood velocities and its indices in healthy men. In the further investigations, the assessment of aerobic fitness and vascular aging has potential by using the criteria of peak systolic and peak diastolic, and its indices.

Variations of the Maximum Blood Flow Velocity in the Carotid, Brachial and Femoral Arteries in a Passive Postural Changes by a Doppler Ultrasound Method

We have developed a blood flow velocimeter to measure maximum blood flow velocity (MBFV) in carotid, brachial and femoral arteries simultaneously by using a Doppler ultrasound technique. This measurement system is based on a continuous wave Doppler ultrasound method with two semicircular piezoelectric (PZT) transducers, one continuously transmitting ultrasound, and the other continuously receiving the echoes. This report is to investigate variations of MBFV in 3 arteries of 5 healthy normal male volunteers during passive postural changes in supine, 90 degrees head-down-tilt (HDT) and 90degrees head-up-tilt (HUT) respectively. As a result of these measurements, we could confirm that MBFV in those arteries especially in brachial and femoral are increased by supine to HDT posture and are decreased by supine to HUT posture. But, its just changed a little in carotid artery. An increasing and a decreasing in MBFV are expected to be an effect of venous pressure and a constant MBFV in carotid artery is caused a cerebral autoregulation.

Pattern recognition system using evolvable hardware

We have developed a high-speed pattern recognition system using evolvable hardware (EHW). EHW is hardware that can change its own structure by genetic learning for maximum adaptation to the environment. The purpose of the system is to show that recognition devices based on EHW are possible and that they have the same robustness to noise as devices based on an artificial neural network (ANN). The advantage of EHW compared with ANN is the high processing speed and the readability of the learned result. In this paper, we describe the learning algorithm, the architecture, and the experiment involving a pattern recognition system that uses EHW. We also compare the processing speed of the pattern recognition system with two types of ANN dedicated hardware and discuss the performance of the system.

Exercise Training Improved Blood Flow Velocity and Autonomic Nervous Activity

The present study aimed to investigate non-invasively the effects of a short-term 4 week aerobic training program on the resting common carotid artery (CCA) blood flow velocity waveforms and autonomic nervous activity in young sedentary healthy subjects. It was hypothesis that training-induced the enhancement of blood flow is associated with the improvement of autonomic nervous function. The CCA blood velocities were measured for 3 minutes at resting sitting posture with synchronized measurement of electrocardiogram (ECG) and brachial blood pressure (BP). Autonomic activity was assessed by low frequency (LF) power, as an index of sympathetic activity and high frequency (HF) power, as an index of parasympathetic activity obtained from power spectral of RR intervals. Training exercise-induced the significant enhancement of all blood velocity waveforms is associated with decreasing of heart rate at rest. The evidence of improvement in training was reinforced by a significant reduction in peripheral vascular resistance and increase in heart rate variability (HRV) and HF power of HRV analysis, an index of vagal tone or parasympathetic activity. However, systolic (SBP), diastolic (DBP) and its mean blood pressure (MBP) are not significantly changed with the training. We conclude that short-term aerobic exercise training could improve cardiovascular and autonomic nervous system functions in the sedentary young men. With the further study, training effect may be simply evaluated using the non-invasive measurement system of blood velocities in CCA.

Synchronized measurements of maximum blood flow velocities in carotid, brachial and femoral arteries, and ECG in human posture changes

In this research, a system has been developed to measure the maximum blood flow velocity simultaneously by an ultrasonic Doppler technique in three arteries during posture changes. As a peculiarity of this system, two semicircular transducers of 15.0 mm in diameter were used as a transmitter to irradiate a wide ultrasonic beam and a receiver. Because, the position relation between an artery and transducers change rapidly during exercise. This system could be applied to a human body changing from a sitting position to an erect position with voluntary muscle constriction. As a result of measurements, the maximum blood flow velocity in femoral artery has been increased significantly in posture changes like the above.

Measurement of blood flow velocity waveforms in the carotid, brachial and femoral arteries during postural change

The purpose of this study was to measure blood flow velocities in carotid, brachial and femoral arteries simultaneously during passive postural change using our developed telemetry measurement system. This system was implemented with synchronized measurement of electrocardiogram (ECG). The velocity waveforms and ECG were continuously measured in six putatively healthy young subjects for 130 s during passive postural changes in supine and 90 degrees head-up-tilt (HUT), respectively. Peak systolic SI and end-diastolic d velocities were obtained from the velocity waveforms in 3 arteries, and using these velocities as an index of d/Sl to assess the velocity waveforms during the postural change. The velocity waveforms of 3 arteries, heart rate (HR), and blood pressure (BP) were assessed for 20 s at the stages of postural change. As a result, HTJT-induced increase in HR was more pronounced in the young subjects. The index of d/Sl in carotid was significantly decreased during HUT, whereas the index of that in brachial and femoral arteries were significantly increased. There was significant increase in diastolic BP but, a non significant change in systolic BP to tilt. The decreased of the blood flow index in the carotid artery was expected to be the effect of cerebral autoregulation (CA) to control blood flow to the brain. In contrast, the blood flow in the brachial and femoral was more influenced of venous pressure (VP) in postural change. In conclusion, HUT produced larger changes in the 3 arteries, particularly in brachial and femoral, and also in HR and diastolic BP. This study demonstrated that synchronized measurement of blood flow velocity waveforms in carotid, brachial, and femoral in HUT postural change using our telemetry measurement device was attainable. Thus, this method could prove to be a useful tool for investigating cardiovascular disease (CD) risk with further research and development.