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The thin-layer chromatographic (TLC) behaviour of 64 ions including Zr(IV) and Hf(IV) has been surveyed on systems composed of silica gel and of nitric acid and nitric acid-hydrogen peroxide media. In the 0.5 mol 1(-1) HNO(3)-3% (w/v) H(2)O(2) solution, only Hf(IV) adsorbed very strongly, whereas Zr(IV) and many other ions showed no or weak adsorption. Stepwise development with diluted nitric acid and subsequently with nitric acid-hydrogen peroxide solution allowed the consecutive separation of three-component mixtures consisting of Zr(IV), Hf(IV) and one of many other accompanying elements, such as Mo(VI), Nb(V), Th(IV), Ti(IV), U(VI) and rare earths(III), to be conducted simply and effectively.

This study was undertaken to elucidate whether phase I appeared at the onset of voluntary and passive arm movements and to compare these results with those of similar leg movements. Instead of the conventional cranking exercise, seven male subjects performed alternately flexion-relaxation of both arms, extension-relaxation of both legs, and combined arm and leg exercise at the rate of about 60 min-1 for four breaths in a sitting position. Similar movements were accomplished passively by the experimenters. In all experiments, minute ventilation increased rapidly within the first breath after the onset of exercise. The difference of ventilation (delta value) between the mean of the first two breaths at the onset of voluntary exercise and that of five breaths during rest was significantly (P < 0.05) greater in arm (7.75 l min-1) than in leg (5.19 l min-1). Passive movement showed a similar tendency. Arm delta ventilation correlated highly (r = 0.74-0.91) with leg delta ventilation and the slope of the regression lines was about 1.2. Heart rate increased abruptly while cardiac output did not always increase rapidly at the onset of locomotion. Oxygen uptake in the voluntary leg exercise continued for 3 min was slightly but nonsignificantly higher than in the arm exercise, indicating the equality of the exercise intensity. In conclusion, ventilatory responses at the onset of the arm exercise are larger than those of the leg in both voluntary and passive conditions regardless of the muscle mass, suggesting the different neurogenic mechanism between arm and leg.

The present study was undertaken to examine the relationship between maximal pulmonary ventilation (VEmax) and potassium concentration ([K+]) or lactate concentration ([La]) of venous blood in man. Nine healthy men performed exercise on a bicycle ergometer at a constant rate of 60 rpm until volitional fatigue. VEmax ranged from 100.4 to 153.2 l/min. In all subjects, potassium concentration measured at 1 min ([K+]1.0) after maximal exhaustive exercise was the highest, and it returned quickly to the resting level within a few minutes during recovery. VEmax was significantly correlated (r = 0.750, p < 0.05) to [K+]1.0, but not to lactate concentration determined at 1 min ([La]1.0) during recovery. These results suggest that a higher increase in blood [K+] may, at least partly, contribute to a greater augmentation of VE during exhaustive exercise.

A lossless and low crosstalk optical switch is most desirable for large scale photonic networks. To realize such a switch, a traveling-wave amplifier is integrated into the slip waveguide of a carrier-injection type optical single-slip structure(S3) switch. Fiber-to-fiber lossless and low crosstalk (an ON/OFF ratio as high as 40dB) are demonstrated in a 2 X 2 cross-bar optical switch that has integrated 4 amplifiers and 8 Y-branch optical switches.

Even for lightwave transmission systems above 10 Gbit/s, highly sensitive and compact photoreceivers are preferable. An avalanche photodiode (APD) with a large gain-bandwidth (GB) product would be one of the most promising candidates for receivers in systems with such extremely high bit rates, as well as in systems with lower bit rates.1 Recently, we reported a superlattice (SL) APD with a GB product of 80 GHz under a 3-dB bandwidth of 12 GHz,2 where the SL allowed us to enhance the ionization-rate ratio for achieving the high GB product.3 To improve the GB product further, it is necessary to reduce the SL multiplication-layer thickness4 by overcoming the problem of the accompanying tunneling breakdown with thinning of the SL layer thickness. Here, we demonstrate an InAlAs/InGaAs SL-APD with a GB product of 130 GHz under a 3-dB bandwidth of 12 GHz by introducing a novel SL structure of less than 0.2-µm thickness.

According to the progresses of ultra-high bit rate optical fiber communication, a space division photonic switching network is desired to realize ultra-large data throughput switching. In designing such a network on a large scale, semiconductor optical traveling-wave amplifiers (TWAs) have been used to reduce optical switch loss[1]. A lossless semiconductor optical switch attained by monolithically integrating a TWA is the most desirable approach for large scale photonic switching networks, because it can be small and enable the network to be enlarged without worrying about loss budget. The larger the photonic switching network, the more important low crosstalk is, since the accumulated crosstalk increase with magnification of the switch matrix[2].

Photonic space division switching networks are one of the most promising switching systems. In designing such a network on a large scale, C. Burke et al. proposed and demonstrated that use of semiconductor optical amplifiers could reduce optical switch loss[1]. A lossless optical switch unit is most desirable for large scale photonic networks because it enables us to enlarge the network without being concerned about optical loss.

Recent progress in optical amplifiers has eliminated the loss limitation in optical-transmission systems. Therefore the maximum transmission length is mainly limited by the waveform deterioration due to the chirping in the modulated light. Semiconductor MQW external modulators are expected to overcome this problem because of their potential for low chirp and high-speed modulation and for optoelectronic integration.1,2 The Mach-Zehnder-type (MZ) modulator has been proposed as one of the most promising since it achieves zero or negative chirping, which maximizes the transmission distance.5

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.

Changes in the time courses of VO2 during constant-load exercise were examined in connection with other cardiorespiratory and blood chemical parameters. Eleven healthy male subjects performed a ramp exercise and three to six constant-load exercises at varying degrees of load using an electro-braked bicycle ergometer. Heart rate, ventilation, and gas exchange were measured during both types of exercise, and chemical parameters of the subject's blood (blood gas, pH, lactate, and electrolytes) were determined during two intensities of constant-load exercise. The time courses of cardiorespiratory and blood chemical data 3 min after the onset of constant-load exercise were fitted by linear regressions to see whether these parameters had reached the steady state or not. Heart rate increased significantly at a lower intensity of constant-load exercise than VE, VO2, and VCO2. While the increase in VCO2 was slower than that of VO2, a definite difference in time courses was not found between VE and VO2. The time courses of changes in blood gas, pH, bicarbonate, and lactate were not correlated with those of VO2. However, changes in blood potassium concentration were closely correlated with those of VO2 in terms of time courses and magnitude. This suggests the possibility that blood potassium may play an important role in the control of VO2 time course during constant-load exercise.

Waveform deterioration due to frequency chirping in a modulated light source limits the maximum transmission distance in multigigabit optical transmission systems. Semiconductor MWQ external modulators are expected to overcome the problems, because of their potential for low chirp and high-speed modulation and for optoelectronic integration.1,2 The Mach-Zehnder type (MZ) modulator has been proposed as one of the most promising, since it achieves zero or negative chirping which maximizes the transmission distance.3 Recently, a highly efficient and small size MQW MZ modulator was reported,4 but its driving voltage was still too high (~10 V with only ~7 dB of extinction ratio) for practical use. Here, we demonstrate a low driving voltage InGaAs/InALAs MQW MZ modulator with high extinction ratio (>15 dB), for 10-Gbit/s long-haul transmission systems operating in the 1.55-μm) wavelength region.

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.

In order to examine whether or not there are initial changes in ventilation at the start of bicycle exercise having work loads of differing intensities are affected with regard to normoxia and to hypoxia accompanying hypocapnia, six healthy male subjects performed submaximal exercise of 30 and 120 W at 60 rpm under normoxic (FIO2 = 0.21) and hypoxic (FIO2 = 0.11) conditions. Resting ventilation was significantly higher in hypoxia than in normoxia. However, no statistically significant differences in the initial change in ventilation at the start of exercise (delta VI assessed breath-by-breath) were found between eucapnic normoxia and hypocapnic hypoxia in both 30 and 120 W exercise. Moreover, blood lactate after exercise did not increase in any conditions as compared with rest. These observations suggest that the neurogenic ventilatory response immediately after submaximal exercise at a work load below the subject's anaerobic threshold is independent from PO2.

In order to investigate the effects of acute hypoxia and accompanying hypocapnia on the ventilatory response at the onset of dynamic exercise, four healthy adult men performed 50W rectangular loads on a cycle-ergometer in normoxic (FIO2 = 0.21) and hypoxic (FIO2 = 0.11) conditions. No statistically significant differences in the initial ventilatory responses to exercise (both delta VI and delta VE assessed on a breath-by-breath basis) were found between eucapnic normoxia (PETO2 approximately 95, PETCO2 approximately 42 Torr) and hypocapnic hypoxia (PETO2 approximately 45, PETCO2 approximately 35 Torr). The present findings support the contention that the neurogenic ventilatory drive at the onset of early exercise is independent from PO2 and PCO2.

We designed and fabricated ultra-small photonic-crystal (PC)-waveguide (WG)-based components of straight-WGs, 60°-bends and Y-splitters, utilizing single-line-defect in the air-bridge type GaAs PC, and revealed their optical properties in detail by observing a transmittance (T) spectrum over a broad wavelength-region from 850 to 1600 nm. For this purpose, we developed a halogen-lamp-based spectrometer for an ultra-thin slab-sample, which has turned out very useful. We also calculated the corresponding T-spectrum by using three-dimensional finite-difference-time-domain method. In all cases where comparison is possible, the observed spectrum agrees essentially with the calculated one. Owing to these broad spectra, we have unambiguously identified the high-T region due to single guided-mode in the respective components. Comparisons of the spectrum between different samples or components, such as the straight-WGs with much different lengths, or the straight-WG and the sharp bend have also helped to reasonably interpret the observed spectra, allowing a comprehensive understanding of optical properties of those components. The propagation loss and the band width in each component could also be estimated from the comparison. The loss is estimated as 1.5 ±0.5 dB/mm for the straight-WG, while less than 1 dB/bend, if it exists, for the bend WG, and both band-widths are broader than 40 nm. We also find that the Y-splitter is capable of dividing light into two ports almost equally in intensity with a total transmittance of more than 85%; the band-width is broader than 40 nm. As a result, we have found that all those should be useful as key components in future ultra-fast planar optical integrated circuits.

We report on the successful development of an ultra-small photonic-crystal(PC)-waveguide-based 120° Y-splitter operating at 1310 nm, which consists of mutually intersecting single-line-defects in the Γ-K direction with an additional air-hole in the middle of the intersection, based on the air-bridge-type GaAs PC of an array of air-holes. The transmittance spectra observed by using a halogen-lamp-based spectrometer newly developed for thin PC-waveguide samples, reveal that a total transmittance of 85% at two output ports is achieved with a band-width as broad as 50 nm. This result indicates that the present Y-splitter should be useful as a key component in future ultraminiature planar optical circuits.

Objective measurement of nasality is very important in terms of clinical evaluation. But there is no definite methodology of objective evaluation of nasality. We already reported that new methodologies of the Laser Doppler Vibrometer (LDV) and Sub‐miniature Electret Microphone (SEM), both of which could detect the nasal/non‐nasal difference of sustained phonemes, seemed valid to evaluate nasality [Kumada et al., 140th ASA Meeting (2000); Kumada et al., 141st ASA Meeting (2001)]. LDV, used recently in an industrial field as well as medical/biological field, is the generator and the detector of the laser to detect the velocity of the object’s vibration by Doppler’s effect. LDV seemed a powerful tool for speech physiology by which vibration of a body wall can be measured during speech and singing, without any contact receiver. The objectives were to evaluate the degree of nasality of phonemes in words by LDV and SEM, and to discuss the possibility of the clinical use of these methodologies. The subjects were 5 healthy Japanese males (Tokyo dialect speakers). The materials were Japanese words /shinkansen/ and /shimbunshi/. Both LDV and SEM systems could detect a nasal/non‐nasal difference in spoken words, and seemed valid to evaluate nasality in speech. Further study is planned using patients (e.g., cleft‐palate) as well as healthy subjects.

It is very important to evaluate nasality objectively in terms of both intersubject (severity of nasality) and intrasubject (validity of treatments, i.e., operation, speech therapy etc.). But there is no definite methodology for an objective evaluation of nasality. Our objectives were to evaluate the degree of nasality with a laser Doppler vibrometer (LDV) and a subminiature electret microphone (SEM) (using an accelerometer as a known standard), and to discuss the possibility of clinical use of these methodologies. LDV, used recently in the industrial field as well as in the medical/biological field, is a generator and detector of lasers to detect the velocity of the object’s vibration by the Doppler effect. The subjects were five healthy Japanese males (Tokyo dialect speakers). Used were sustained phonations (about 2 s) of /m/ and five Japanese vowels (/i/, /e/, /a/, /o/, /u/), and the Japanese words, shinkansen and shimbunshi (six repetitions for each phoneme). By both LDV and SEM systems, a significant...

Listening tests were performed to clarify the subjective effects of seating arrays. First, a qualitative assessment was made of the subjective effects introduced by the seating array. Test signals were prepared by convolving dry music with impulse responses measured in a scale model consisting of a stage, a floor with audience but no walls or ceiling. The measured impulse responses showed that the seating array caused an increase in amplitude below 80 Hz as well as a large dip at 150–200 Hz. The results of listening tests demonstrated that the seating array affected not only bass perception but also loudness. Second, it was investigated whether reflections from the ceiling and walls can compensate for an excess or deficiency of perceived bass caused by the seating array. In addition, the relation between the frequency characteristics of sound fields and bass perception is discussed. Test signals were prepared by adding a ceiling reflection and reverberation to test signals used in the first test. The results indicated that to a certain extent they can compensate for an excess or deficiency of perceived bass. It is suggested that bass perception should be evaluated according to the frequency characteristics of sound fields within the first 100 ms or so after the direct sound.

New methods for objective evaluation of nasality were introduced, including laser Doppler vibrometer, contact microphone system, and small microphone system. Subjects were two Japanese healthy males who speak Tokyo dialect. Tasks were sustained phonations of five Japanese vowels and /m/, repetitions of /ai/ and /mami/, and Japanese words of /shinksnsen/ and /shinbunshi/. Vibration of nasal skin was detected by laser Doppler vibrometer in terms of velocity (Nv), and by contact microphone in terms of deviation (Nc). Vibration of neck skin on larynx was detected by contact microphone (Lc). Sound radiating from nares was detected by small microphone (Nm). Sound radiating from nares and mouth was detected by standard microphone (NOm). The accelerometer system was used as standard, consisting of two pickups, one of which detected vibration of nasal skin (Na), and the other, neck skin on larynx (La). Nv/Lc, Nv/NOm, Nc/Lc, Nm/NOm were compared with Na/La. These values were normalized as the value for sustained /m...

This paper discusses a scale model experiment for room acoustic design of the Yokohama Minatomirai Concert Hall which was opened in June 1998. Priority was given to subjective evaluation in the acoustical design process. To this end a measure to improve S/N ratio of the impulse response and filtering procedure for cancellation of the influence of sound source were investigated. Binaural impulse responses measured with different boundary conditions of the hall were convolved with dry sources, and simulated sounds were compared subjectively. The examination of the auralization reflected on interior design. Comparison of subjective and objective properties with full scale and scale model has been carried out in order to verify auralization using scale model experiment. Good agreement on both evaluations was obtained.