PACS 71.20.Nr, 78.20.Ci, 78.55.Cr InN crystals are grown on sapphire substrates by a plasma assisted MBE system. The carrier concentration of the samples are 2×10 18 −1×1019 cm -3. Optical transmission and reflectance measurements are performed on these samples in a temperature range of 8 -300 K. The resultant spectra are analysed by theoretical spectra based on a LO-phonon plasmon coupling scheme for phonon related factor and nonparabolic conduction band structure for electronic transition factor. The observed absorption edge is estimated to mainly originate from the valence band to conduction band transition rather than defect or impurity related transition on the basis of the electron concentration dependence of the momentum matrix element. The bandgap energy is about 0.63 eV, and increases with the temperature decrease.
Ventilatory response during external dead space (tube) breathing and C02 inhalation for given increase in PETco2 were compared at different levels of PETo2 (hyperoxia, normoxia, and hypoxia) in human subjects. At all the PETo2 levels studied, magnitude of increment in minute ventilation (VE) and tidal volume were larger in the dead space breathing than in the C02 inhalation. The slope of C02-ventilation response line was significantly steeper in the dead space breathing only in the hypoxic condition. There was no significant difference in frequency response to C02 between the two methods. These results suggested that augmented ventilatory response to C02 in the dead space breathing occurs in the condition of peripheral chemoreceptor activation.
PACS 78.30.FsInN crystals are grown on sapphire substrates using a plasma-assisted MBE system. The carrier concentrations of the samples are 2 × 10 18-1 × 10 19 cm -3 . Optical transmission and reflectance measurements are performed on these samples in the temperature range 5 -300 K. The resultant spectra are analysed by theoretical spectra based on the LO-phonon-plasmon coupling scheme for the phonon-related factor and non-parabolic conduction band structure for the electronic transition factor. The observed absorption edge is estimated to originate from a valence band to conduction band transition rather than a defect-or impurity-related transition. It is estimated that InN has a bandgap energy in the range 0.59 -0.65 eV.
BackgroundConcomitant use of clarithromycin (CAM) and rifampicin (RFP) for the treatment of pulmonary Mycobacterium avium complex (MAC) disease affects the systemic concentrations of both drugs due to CYP3A4–related interactions. To date, however, there has been no report that investigates the long–term relationship between the drug concentrations, CYP3A4 activity, and clinical outcomes. Our aim was to investigate the time course of the drug levels in long–term treatment of subjects with pulmonary MAC disease, and examine the correlation of these concentrations with CYP3A4 activity and clinical outcomes.MethodsUrine and blood samples from nine outpatients with pulmonary MAC disease were collected on days 1, 15, and 29 (for four subjects, sample collections were continued on days 57, 85, 113, 141, 169, 225, 281, 337, and 365). Serum drug concentrations and urinary levels of endogenous cortisol (F) and 6 beta-hydroxycortisol (6βOHF), the metabolite of F by CYP3A4, were measured, and evaluated 6βOHF/F ratio as a CYP3A4 activity marker. In addition, the clinical outcomes of 4 subjects were evaluated based on examination of sputum cultures and chest images.ResultsThe mean 6βOHF/F ratio increased from 2.63 ± 0.85 (n = 9) on the first day to 6.96 ± 1.35 on day 15 and maintained a level more than double initial value thereafter. The serum CAM concentration decreased dramatically from an initial 2.28 ± 0.61 μg/mL to 0.73 ± 0.23 μg/mL on day 15. In contrast, the serum concentration of 14-hydroxy-CAM (M-5), the major metabolite of CAM, increased 2.4-fold by day 15. Thereafter, both CAM and M-5 concentrations remained constant until day 365. The explanation for the low levels of serum CAM in pulmonary MAC disease patients is that RFP-mediated CYP3A4 induction reached a maximum by day 15 and remained high thereafter. Sputum cultures of three of four subjects converted to negative, but relapse occurred in all three cases.ConclusionsOur study demonstrated that serum CAM concentrations in pulmonary MAC disease patients were continuously low because of RFP-mediated CYP3A4 induction, which may be responsible for the unsatisfactory clinical outcomes.
Cross-sectional studies on hypercapnic and hypoxic ventilatory chemosensitivities were performed in 71 children ranging in age from 7 to 18 yrs. The subjects were classified into 6 successive 2-year age groups. CO2 ventilatory response was measured by rebreathing 5 % CO2 in Oz, a slight modification of the method originally proposed by Read. The results were evaluated when the C02-ventilation feedback control system was supposed to have attained the open-loop condition. Hypoxic ventilatory response was measured by the isocapnic progressive hypoxia test. To obtain good reproducibility in the ventilatory response, end-tidal P~oz was maintained at 5 mmHg higher than the resting condition throughout the test. Normalized ventilatory responses to CO2 by body surface area (S/BSA) progressively decreased from the 7-8 through the 11-12 yr groups, and then tended to decrease further in a more gradual manner with increasing age. This trend was very similar to the normalized CO2 output (V"oz/BSA), but did not parallel so closely the normalized Oz intake (Voz/BSA). When ventilatory and metabolic parameters were normalized by body weight (BW), or the lean body mass (LBM), qualitatively similar relationships between CO2 sensitivities and metabolic parameters were also obtained. Contrary to the hypercapnic response, hypoxic ventilatory chemosensitivities were not significantly different among the 6 different age groups. We concluded that normalized hypercapnic chemosensitivity decreased during growth and corresponded well with decreased CO2 output per unit body mass.Key words : hypercapnic ventialtory response, hypoxic ventilatory response, body weight, body surface area, lean body mass.
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