A fiberscopic analysis of velopharyngeal movement before and after primary palatoplasty in cleft palate infants

The usefulness of bioelectrical impedance (BI) with anthropometry to measure total body water (TBW) was evaluated in very-low-birth-weight (VLBW) infants. A specific regression equation to measure TBW in a VLBW population was developed by simultaneously using the H2[(18)O] dilution method and BI in 12 infants with a gestational age of 24-30 wk and weighing <1200 g at birth. After an oral dose of H2[(18)O], the tracer dilution was measured in expired carbon dioxide. BI measurements were made with a model BIA-101 apparatus (RJL Systems, Detroit). Electrodes were placed in the standard position as well as proximally on the leg and the forearm. The best correlation was observed between body weight and TBW (r = 0.989). For BI, the best correlation was obtained when gestational age was used as a covariable along with body weight and crown-heel length (r = 0.985). The correlation was comparable with proximal electrode placement (r = 0.985). The new correlation was evaluated in 6 infants weighing < 1008 g. A significant correlation between BI and H2[(18)O]-measured TBW was observed (r = 0.988). Published regression equations for infants consistently gave higher estimates of TBW in another group of 14 infants weighing <1200 g than did the new correlations. TBW represented 84-95% of body weight in these VLBW infants. TBW could be computed simply from body weight alone. Use of BI and length as covariables did not add significantly to the estimate of TBW in VLBW infants.     

Secondary osteoporosis and its treatment--diabetes mellitus

Japanese epidemiological study showed higher frequency of osteopenia/osteoporosis in diabetic patients as compared with sex- and age-matched control. The mechanism by which bone loss occurs in diabetic patients could be explained by a reduction of insulin/insulin-like growth factor-I action, sustained hyperglycemic state, a generation of advanced glycosylation end-products, and diabetic complication such as neuropathy, nephropathy and myopathy. Osteoblast deficit is hypothesized to play a major role in the occurrence of diabetic osteopenia. Besides the deficiency of insulin and insulin-like growth factor-I, we demonstrated that sustained hyperglycemia alone causes suppression of osteoblast proliferation and its response to parathyroid hormone and 1 alpha, 25-dihydroxyvitamin D, Hyporesponse of osteoblast to 1 alpha, 25-dihydroxyvitamin D, was also confirmed in diabetic patients as reflected by a reduction in an incremental response of serum osteocalcin during 1 alpha, 25-dihydroxyvitamin D administration. The regimens having stimulatory effect on bone turnover, such as intermittent PTH therapy and vitamin D, are recommended to treat diabetic osteopenia, besides improvement of diabetic control state.     

Tunneling through ultrathin GaAs n++-p++-n++ barrier grown by molecular layer epitaxy

The I-V characteristics of ultrathin GaAs n⁺⁺-p⁺⁺ -n⁺⁺ barrier structures with a 45 Å thick p⁺⁺ layer grown by molecular layer epitaxy (MLE) have been measured at room temperature and 77 K. The tunneling probability for this structure has been calculated as a function of effective tunneling width. It was found that good agreement between experiment and calculation is obtained when the effective tunneling width is assumed to be 75 Å, which is much smaller than the depletion width about 190 Å measured by C-V method. This fact indicates that the depletion width approximation cannot be used to measure the exact tunneling width for ultrathin barrier devices     

Ballistic and tunneling GaAs static induction transistors:nano-devices for THz electronics

GaAs static induction transistors (SIT) with 10-nm scale channel and with a 100-nm channel were fabricated with molecular layer epitaxy (MLE). Area-selective epitaxy of GaAs/AlGaAs/GaAs was used for the gate. Temperature dependence of current-voltage (I-V) characteristics of the 100-nm SIT indicates ballistic injection of electrons. In the 10-nm scale SIT, electrons are transported ballistically in the drain-side electric field. Direct tunneling is responsible for the transport through the potential barrier. It is indicated by the temperature dependence and by the electroluminescence spectrum. Electron transport in the 10-nm scale SIT is nearly scattering-free. The plausible estimation of the electron transit time is 2·10^-14 s; the worst case estimation based on saturated drift velocity gives 1·10^-13 s. It makes the ISITs suitable for THz applications. Multiple area-selective MLE GaAs regrowth was used as a tool for automatic definition of the channel length     

Fabrication and characteristics of GaP-AlGaP tapered waveguide semiconductor Raman amplifiers

We have fabricated GaP-AlGaP tapered waveguide semiconductor Raman amplifiers, and analyzed the effect of tapering in pulse-pumped high-gain operation. The finesse measurement and 80-ps pulse pumped Raman amplification experiment were performed. Although the tapering has caused additional optical loss, the highest gain of 23 dB has been obtained for a tapered waveguide with input facet of 6.0 /spl mu/m/sup 2/ and back facet of 2.9 /spl mu/m/sup 2/ at averaged input power of 170 mW (peak power 26 W). It is shown that the optical loss of the pump light is more severe than the linear optical loss of the signal light when the gain is higher than 20 dB.     

Ultrafast all‐optical switching using pulse trapping by ultrashort soliton pulse in birefringent optical fiber

Ultrafast all‐optical switching by use of pulse trapping in birefringent optical fiber is demonstrated both experimentally and numerically. The wavelengths of the control soliton pulse and the trapped soliton pulse are shifted to satisfy the condition of group velocity matching. Furthermore, the energy of the trapped pulse is increased through Raman gain of the control pulse. Only a signal pulse in the pulse train with temporal separation of about 1.2 ps is successfully picked off. The repetition frequency corresponds to 0.83 THz. The spectrogram of the optical switching is directly observed using the X‐FROG technique. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 158(3): 38–44, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20470     

Frequency-Tunable Terahertz-Wave Generation from GaP Using Cr:Forsterite Lasers

We have constructed THz spectrometers using the widely frequency-tunable THz-wave generated from GaP crystal pumped at 1.2 µm region using two Cr:forsterite lasers and compared with that pumped at 1 µm region using a YAG laser and an optical parametric oscillator (OPO). The systems have sufficient resolution for observation of solids and liquids at room temperature. We have measured Terahertz absorption spectra of all 20 kinds of amino acids which form proteins.     

High-resolution GaP Terahertz Spectrometer and Its Application to Detect Defects in Gamma-irradiated Glucose Crystal

We developed high-resolution GaP THz signal generator using Cr:Forsterite lasers with gratings as both a pump and a signal beam for difference-frequency generation. A line width of less than 500 MHz and a wide tunable frequency range (0.6–6.2 THz) provide sufficient resolution for measuring materials with sharp absorption bands using the generator as the light source for a THz spectrometer. This is suitable for materials such as gases or solid samples at low temperatures. We demonstrated the detection of defects in organic materials, as they appear as slight deviations in the absorption frequency in the THz region.