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An AlInAs-oxide current-confinement structure was introduced into a III–V/Si-on-insulator (SOI) hybrid laser for realizing an efficient light source composed of III–V/Si hybrid photonic integrated circuits. Lasing of the hybrid Fabry–Pérot laser was confirmed after introduction of the confinement structure providing both optical and electrical confinement. We determined the lasing characteristics of the designed hybrid laser, which showed a low threshold current and high external differential quantum efficiency comparable to that of conventional lasers fabricated on III–V compound semiconductor wafers. Comparison of the photoluminescence spectra of the III–V/SOI hybrid wafers before and after the process proved that oxidation had no influence on the active layer. The threshold current and external differential quantum efficiency of the fabricated laser with a stripe width of 4.5 µm and cavity length of 500 µm were obtained as 50 mA and 11%/facet, respectively. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to determine whether current cardiovascular fitness or weekly physical activity more important for lowering cardiovascular disease (CVD) risk factors regardless of ages in healthy Japanese women. Methods: 358 females participated in our study. Most of them live in Toyota City. Weekly physical activity was measured by an accelerometer attached to the subject's waist for one week. To determine cardiovascular fitness, VO2 max was estimated by the sub-maximal cycle test. Major CVD risk factors included TG, TC, HDL-c, LDL-c, Apo A-I, Apo B, systolic blood pressures, and body fat content. Results and discussion: The relationship between weekly physical activity and VO2 max were positively related with a moderate degree of significance. Our findings suggest that regular physical activity offers benefits to physically fitness. Conventional CVD risk factors, as well as their simple correlations with cardiovascular fitness and physical activity, were found. Most of the individual risk factors were more closely associated with cardiovascular fitness, than with physical activity in women after the data was age-adjusted. The evidence supported that the reduction of selected CVD risk factors are more closely linked to improved cardiovascular fitness than to physical activity in middle-aged women. [ABSTRACT FROM AUTHOR]

Purpose: The previous study showed that short-duration intermittent hypoxia causes additive effects on improving endurance capacity during chronic exercise training via enhancing fatty acid metabolism (Physiol Rep 4(7), el2744, 2016). The present study was designed to investigate the effects of short-duration intermittent hypoxia on endurance capacity in long-term trained mice. Methods: Mice of training group were housed in a cage with wheel activity device for 7 weeks from five weeks old. Thereafter trained mice were subjected to either normoxic treadmill training (Tr) or training with short-duration intermittent hypoxia (12% O2 for 15-min, room air for 10 min, 4 times, IntTr) for 4 weeks. Results and Discussion: Maximal exercise capacity was significantly greater in the IntTr group (by 36%) than in the Tr group. Total CPT activity in plantaris muscle (PL) was significantly greater in the IntTr group (by 22%) than in the Tr group. In the PL and deep red region of gastrocnemius, increases in the proportion of type IIA and 11 AX fibers, and decrease in the proportion of type IIX fiber were observed in both training groups. Whereas increase in the proportion of type I fiber was observed in the IntTr group only. These results suggest that exercise training with short-duration intermittent hypoxic exposure facilitates endurance performance via enhancing fatty acid metabolism and slow-twitch fiber composition in long-term trained mice. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to determine the effects of basal vascular tone on mechanical vasodilation of the feed arteries of rat soleus muscle. Methods: Mechanical vasodilation was measured in caged control male Wistar Hannover rats (7-72 weeks of age). Soleus muscle feed arteries were isolated and mounted on a micropipette in a sealed chamber. Arteries were pressurized to 80 mmHg. Pressure pulses of 250 mmHg were delivered for 1 s and as a series of 10 repeated 1-s pulses at 1-s intervals. Luminal diameter was measured under an inverted microscope. Results and Discussion: The mechanical vasodilation of the feed arteries of rat soleus muscle peaked at 40%-50% of the basal vascular tone. The amplitude of the mechanical dilation was significantly larger in the young rats (15.2 ± 1.86% (n = 16)) than in the mature rats (9.13 ± 1.86% (n = 16)) (p<0.05). There were no significant differences in the basal tone at rest between the young and mature rat groups. Our findings indicate that it is important to evaluate the amplitude of the mechanical vasodilation of the feed arteries of rat soleus muscle under the 40%-50% of basal vascular tone condition. These results indicate that basal tone is a crucial factor in determining the amplitude of mechanical vasodilation. [ABSTRACT FROM AUTHOR]

Purpose: Excessive of visceral fat accumulation is well known to be associated with life-style diseases such as type-2 diabetes. Intramuscular fat has been reported as a factor causing insulin resistance (IR) in obesity. Skeletal muscle attenuation (CT value) determined by computed tomography is associated with skeletal muscle fat content. This study attempted to calculate HOMA-R, an indicator of IR from the amount of skeletal muscle CT values. In addition, we examined the relationship between IR, exercise habits, and maximum oxygen uptake. Methods: The subjects were 33 healthy athletes and 29 non-athletes at our university. Skeletal muscle CT values were measured at the following points: erector spinae, psoas major, gastrocnemius, soleus, and tibialis anterior muscles. We used HOMA-R as an index of IR. Results and discussion: A high correlation was observed between VFA and HOMA-R in healthy adult males. A significant relationship was observed between HOMA-R and both V02max and VFA, but was no significant relationship between skeletal muscle CT value and either HOMA-R or VFA. However, individuals engaged in regular endurance exercise had higher muscular fat despite being markedly insulin sensitive. Higher muscular fat of long distance runner is considered that does not cause IR. [ABSTRACT FROM AUTHOR]

III–V/Si hybrid integration with direct bonding is an attractive method of realizing an electrophotonic convergence router with a small size and a low power consumption. Plasma-activated bonding (PAB) is an effective approach for reducing thermal stress during the bonding process because PAB achieves a high bonding strength with low-temperature annealing. This time, the fabrication of a GaInAsP/silicon-on-insulator (SOI) hybrid laser with Si ring-resonator-type reflectors was demonstrated by N2 PAB. By measuring the lasing spectra, we confirmed the reflective characteristics resulting from the cascaded Si ring resonators. We also investigated kink characteristics, which occur around the threshold current, of the current–light output (I–L) characteristics, and successfully approximated the kink characteristics by considering saturable absorption occurring at the III–V/Si taper tip. The taper structure was investigated in terms of a passive device as well as an active device, and a structure for eliminating saturable absorption was proposed. [ABSTRACT FROM AUTHOR]

Purpose: This study was designed to (1) investigate the effects of acute short-duration intermittent hypoxia on muscle mRNA and miroRNA expression levels, and to (2) clarify how short-duration intermittent hypoxia causes additive effects on improving endurance capacity during chronic exercise training. Methods: Exp.-l: Male ICR mice were subjected to either acute 1-h hypoxia (12% O2), acute short-duration intermittent hypoxia (12% O2 for 15-min, room air for 10 min, 4 times, Int-Hypo), or acute endurance exercise (Ex). Exp.-2: Mice were subjected to normoxic exercise training with or without hypoxic exposure for 3 weeks. Results and Discussion: PGC-la mRNA levels were significantly greater than control at 3 h post Ex and at 6 h post Int-Hypo. Expression levels of mi-23a were lower than control at 6-24 h post Int-Hypo. Training with intermittent hypoxia (IntTr) increased maximal exercise capacity greater than training alone. The HAD and total CPT activity levels were significantly enhanced after the IntTr only in deep red gastrocnemius muscle. Both PPAR5 and PGC-la mRNA levels were significantly greater in IntTr than in sedentary control. These results suggest that exercise training in normoxia with short-duration intermittent hypoxic exposure may be a beneficial strategy for increasing endurance performance via enhancing fatty acid utilization in mitochondria. [ABSTRACT FROM AUTHOR]

A pair of grating couplers with apodized structure, sandwiched by metal mirrors, was proposed for inter-layer coupling between multilayer waveguides based on hydrogenated amorphous silicon (a-Si:H). We proved theoretically that the introduction of an apodized grating coupler yields a high coupling efficiency of about 90% even for an inter-layer distance of several micrometers. In addition, this high coupling efficiency was obtained for a large bandwidth by adjusting the grating period. [ABSTRACT FROM AUTHOR]

The partial removal of the III–V layers of a III–V/silicon-on-insulator hybrid wafer was investigated to realize III–V/Si hybrid photonic integrated circuits. Using transmission electron microscopy, we found that an amorphous layer was generated at the interface of a III–V/Si wafer fabricated by N2-plasma-activated bonding. In order to remove the III–V layers including the amorphous layers without damage to the Si surface, several etching processes were carried out, and the surface conditions were evaluated by X-ray photoelectron spectroscopy. As a result, we demonstrated comparable propagation losses in Si wire waveguides with and without the bonding/removal processes. [ABSTRACT FROM AUTHOR]

Higher-order mode coupling at bending waveguides between Si multimode waveguides and 500-nm-wide wire waveguides was evaluated for low-loss Si multimode waveguide circuits. By narrowing the multimode waveguides to the wire waveguides at the bending section, the TE fundamental mode propagation was strongly maintained in the entire circuit, and the spectral fluctuation was improved from 10 dB to less than 1 dB for a 4-µm-wide waveguide. Furthermore, propagation losses were reduced to less than 1 dB/cm with waveguide widths greater than 1 µm. [ABSTRACT FROM AUTHOR]

We investigated the effect of zinc supplementation on growth and serum IGF-1 levels in 10 prepubertal Japanese children with idiopathic short statures, who had serum zinc levels of less than 80 µg/dL. Subjects were started on oral zinc supplementation at a dose of 25 mg once daily. In three children, the doses were increased by 50 mg once daily during the study period of 12 mo. The serum zinc levels rose in all subjects and reached a normal range (beyond 80 µg/dL). However, it was found that zinc supplementation did not promote growth. Although the mean IGF-1 standard deviations significantly increased, the majority did not reach the normal range. There were no significant adverse events other than mild gastrointestinal symptoms in 4 out of 10 subjects during the supplementation period. The most likely reason why growth was not promoted is that the zinc supplementation dosage was not enough to stimulate IGF-1 generation and subsequent growth velocity. [ABSTRACT FROM AUTHOR]