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Independent component analysis (ICA) is a useful method for blind source separation of two or more signals. We have previously proposed a new method combining ICA with the complex discrete wavelet transform (CDWT), in which voice and noise signals were separated using a new method. At that time, we used a simulated signal. In this study, we analyze measured biological signals by using a new method, and discuss its effectiveness. As an experiment, we try to separate an electromyogram (EMG) signal from an electrocardiogram (ECG) signal.

Background and purpose In order to identify sleep disorders by thoracic impedance plethysmography (TIP), we propose several new techniques: the application of an adaptive filter, a scaled Fourier linear combiner (SFLC) to eliminate cardiac-derived fluctuation in the impedance waveform, and the use of heart rate variability (HRV) to ascertain whether the airflow is obstructed. Patients and methods Laboratory simulation experiments on four healthy individuals and actual overnight measurements on five patients with sleep disorders were carried out. Amplified thoracic impedance change (Δ Z ), ECG, a phonocardiograph, a pneumotachograph and a standard polysomnograph were recorded. The SFLC was applied to Δ Z to selectively extract the cardiac-synchronous component (Δ Z CSC ), and the remainder of the waveform (Δ Z REM ) was low-pass filtered to estimate the waveform driven by respiration. The HRV was divided into respiratory synchronous (HRV R ) and low frequency (HRV L ) components. Results The SFLC could drastically extract Δ Z CSC from Δ Z and thereby demonstrate a Δ Z REM pattern quite similar to the flow–volume curve of the pneumotachograph. Central sleep apnea could be identified as the cessation of Δ Z REM and concomitant attenuation of HRV R . Obstructive sleep apnea could be identified as the maintenance of rhythmic but attenuated variations of Δ Z REM accompanied by asynchronous fluctuation of HRV R against Δ Z REM . Central hypopnea could be identified as a normal but attenuated waveform in both Δ Z REM and HRV R . A large fluctuation in HRV L was observed during repetitive appearances of apnea/hypopnea in the nocturnal experiments. Conclusion The modified TIP together with HRV provides a superior tool for accurate and convenient definition of sleep apnea syndromes.

The purpose of this study was to estimate the differences in neuromuscular fatigue among prolonged pedalling exercises performed at different pedalling rates at a given exercise intensity. The integrated electromyogram (iEMG) slope defined by the changes in iEMG as a function of time during exercise was adopted as the measurement for estimating neuromuscular fatigue. The results of this experiment showed that the relationship between pedalling rate and the means of the iEMG slopes for eight subjects was a quadratic curve and the mean value at 70 rpm [1.56 (SD 0.65) microV.min-1] was significantly smaller (P0.01) than that at 50 and 60 rpm [2.25 (SD 0.54), and 2.22 (SD 0.68), respectively]. On the other hand, the mean value of oxygen consumption obtained simultaneously showed a tendency to increase linearly with the increase in pedalling rate, and the values at 70 and 80 rpm were significantly higher than those at 40 and 50 rpm. In conclusion, it was demonstrated that the degree of neuromuscular fatigue estimated by the iEMG changes for five periods of prolonged pedalling exercise at a given exercise intensity was different among the different pedalling rates, and that the pedalling rate at which minimal neuromuscular fatigue was obtained was not coincident with the rate at which the minimal oxygen consumption was obtained, but was coincident with the rate which most subjects preferred. These findings would suggest that the reason why most people prefer a relative higher pedalling rate, even though higher oxygen consumption is required, is closely related to the development of neuromuscular fatigue in the working muscles.

To examine the ventilatory response at the onset of passive leg movements during sleep in man and the concomitant changes in cardiac output (Qc), five healthy male subjects had their knee joints extended and flexed alternately at a frequency of about 60.min-1 for about 8 s. Minute ventilation (VI), respiratory frequency, tidal volume, end-tidal partial pressure of carbon dioxide and of oxygen, stroke volume (SV), heart rate (fc) and Qc were measured before, during and after passive leg movement during sleep stage III or IV (SLEEP). These values were compared with those of the awake condition (AWAKE). The VI increased significantly (P0.05) compared with the mean of five breaths preceding the movement (pre-movement) within one or two breaths at the onset of passive leg movements in both conditions. The difference between the mean of the first and second breaths after the onset of leg movement and pre-movement was 5.2 (SEM 1.9) l.min-1 for SLEEP and 2.7 (SEM 1.1) l.min-1 for AWAKE, respectively. Four of the five subjects showed a larger increase in ventilation during SLEEP compared with AWAKE. The fc increased significantly (P0.05) at the beginning of the passive movement in all cases, while SV showed an increase or decrease so that Qc showed no significant change in either condition. These results would suggest that afferent drive from moving limbs could produce an increase in ventilation without any change in Qc.

A method to determine lattice parameters and parameters characterizing the bending strain of the lattice, the direction and magnitude of the displacement field of the bending strain, by using higher-order Laue zone (HOLZ) reflection lines observed in convergent-beam electron diffraction patterns is proposed. In this method, all of the parameters are simultaneously determined by a fit of two Hough transforms of experimental and kinematically simulated HOLZ line patterns. This method has been used to obtain two-dimensional maps of lattice parameter a, the direction and relative magnitude of the displacement field in a Si substrate near a SiGe/Si interface.

Independent Component Analysis (ICA) is a useful method for blind source separation of two signals or more. We have previously proposed a new method combining ICA with the complex discrete wavelet transform (CDWT). In this case, the voice and the noise were separated using a new method. At that time, we used the simulation signal. In this study, we analyze measured biological signals by using this new method, and discuss its effectiveness. As an example, we tried the separation of the EMG signal and the ECG signal.

We have developed a micro-multipoint laser Doppler velocimeter (µMLDV), which is the newest version of our improved laser Doppler velocimeter (LDV). This device can potentially be used clinically for the evaluation of the internal diameter of blood vessels, inspection of blood vessel protrusions and diagnosis of melanoma. To date, we have verified the accuracy of this device for three-dimensional measurement of blood vessels in vivo and measurement of melanoma. The state of blood flow is one of the evaluation criteria for tissue fixing. However, the state of blood flow is difficult to determine visually. If the state of blood flow can be visualized using this system, without damaging the affected area, it is possible to evaluate fixing noninvasively. Therefore, we measured normal blood vessels and cases in which there was no blood flow for comparison and verified the possibility of using the µMLDV as an evaluation device. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

In order to examine the origin and role of nitric oxide (NO) in exhaled air during exercise, exhaled NO outputs of 8 healthy human subjects were compared using different breathing methods, through the mouth or nose, at two intensities of bicycle exercise. The concentration of NO in the exhaled air and ventilatory gas exchange variables were measured by a chemiluminescence analyzer and a mixing chamber method, respectively. The concentration and total output of NO in the expired air was significantly higher under nasal breathing than under oral breathing for both exercise intensities, whereas no significant difference was observed in cardiorespiratory variables between them. NO output increased significantly when exercise intensity was increased from unloaded (0 W) to 60 W under nasal breathing, but not under oral breathing. A negative correlation among subjects was found between NO output and minute ventilation in both breathing methods only for unloaded exercise. Data indicate that nasal airways have a large contribution, at least 50% of total NO output in the exhaled air during nasal breathing, but this nasal NO may have no further modulation on respiratory function during submaximal exercise by healthy humans.

Ventilatory responses at the onset of passive and active exercise with different amount of exercising muscle mass were studied in 10 healthy male subjects. Four exercise tests were performed for each subject with appropriate intervals on the same day, i.e., two voluntary exercises of one leg or both legs and two passive exercises of one leg or both legs. Inspiratory minute volume (VI), end-tidal CO2 and O2 partial pressures (PETCO2, PETO2) were measured breath-by-breath using a hot-wire flowmeter, infrared CO2 analyzer, and a rapid O2 analyzer. Average values of VI were obtained from 5 breaths at rest preceding exercise and the first and second breaths after the onset of exercise. The ventilatory response to exercise was calculated as the difference (delta) between the mean of exercise VI and mean of resting VI. In this study, the PETCO2 decreased by about 0.5 Torr in four exercise tests, though the decrement of PETCO2 was not statistically significant. The average values and standard deviation of delta VI were 4.22 +/- 1.63 l/min for the one leg and 6.46 +/- 1.80 l/min for the two legs in the active exercise, and were 2.46 +/- 1.12 l/min for the one leg and 3.44 +/- 1.55 l/min for the two legs in the passive exercise, respectively. These results suggest that in awake conditions, the ventilatory response at the onset of passive or active exercise does not increase additively with the increasing amount of muscle mass being exercised.

Although the mechanisms of exercise hyperpnea especially in phase I has been obscure, central and/or peripheral neurogenic drive is thought to be the cause for rapid increase in ventilation at the onset of voluntary exercise. Many previous investigations proved that passive exercise also produced a rapid increase in ventilation. These results may suggest that peripheral neurogenic components should be the main cause for exercise hyperpnea. However, this passive exercise was performed in an awake condition when the higher center is still active. It is considered that the higher center may influence the respiratory center in that case. So it is necessary to clarify the ventilatory response in passive exercise while the higher center is not active, for example, during sleep conditions. On the other hand, Wasserman et al.1 proposed cardiodynamic hypotheses that ventilatory response is linked to changes in cardiac output. To confirm this theory especially in phase I, cardiac output must be measured correctly within a short time at the onset of exercise. Moreover, in a supine position, the hemodynamic response is rather different from the upright position, which affects the cardiac output. Thus, it is required to reveal the relationships between the ventilatory and cardiac response to passive exercise during sleep in a supine position. The purpose of this study is, therefore, to elucidate whether or not 1) an abrupt increase in ventilation would be observed at the onset of passive exercise during sleep in man and 2) whether these changes in ventilation are linked with concomitant changes in cardiac output in a supine position.

Blood flow in the right and left forearms was determined by venous occlusion plethysmography in ten healthy male subjects before and after training with a hand ergometer. The subjects in group A and B were trained using work loads of 1/3 and 1/2, respectively, of maximum grip strength 6 days/week for 6 weeks. It was found that the blood flow in the left (untrained or contralateral) forearm during exhaustive training of the right hand increased gradually with increasing training periods, and that after 6 weeks of training, grip strength, endurance and peak blood flow of the forearm increased significantly not only in the trained forearm, but also in the untrained forearm. From these results, it is suggested that the increase of blood flow in the contralateral limb after training may, at least in part, be related to the cross transfer effect of muscular endurance.

Calf and thigh blood flows in both of right and left legs were measured simultaneously after isometric contraction of the right thigh muscle. Isometric contraction was performed at a force of about 50% of maximal voluntary contraction for 15 sec. The thigh blood flow of the right leg increased immediately after voluntary contraction in all subjects, while the calf blood flow of right leg decreased conversely in spite of exercised ipsilateral leg.