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To examine whether maternal indomethacin therapy affects human fetal pulmonary arterial vascular impedance without constriction of the ductus arteriosus and to determine the changes in the pulmonary arterial vascular impedance in the presence of ductal constriction.In this cross-sectional study, 52 normal fetuses without maternal medication (control group), 33 fetuses without ductal constriction (Study group I) and 11 fetuses with ductal constriction (Study group II) during maternal indomethacin therapy between 24 and 34 weeks of gestation were examined by Doppler echo-cardiography. Blood velocity waveforms across the proximal right or left pulmonary artery were obtained and the pulsatility index (PI) of the proximal pulmonary arteries was calculated.In the control group, the proximal pulmonary artery PI was higher (p0.0001) at 24-25 weeks (n = 7) (3.73 +/- 0.33; mean +/- SD) than at 33-34 week of gestation (n = 11) (2.98 +/- 0.27). The PI was constantly greater (p0.005) in Study group I than in the control group. However, in this group the mean average weekly decrease in the PI of the proximal pulmonary arteries was similar to that in the control group. After 26 weeks of gestation, the PI values in Study group II were significantly higher than in the control group (27 weeks: 4.12 vs. 3.34 (p0.005); 30 weeks: 4.48 vs. 3.14 (p0.0001); 34 weeks: 4.96 vs. 3.00 (p0.0001), respectively).Human fetal pulmonary arterial vascular impedance is increased by maternal indomethacin therapy even without ductal constriction. In the presence of ductal constriction, the magnitude of the increase in the vascular impedance is related to the gestational age.

Diffractive optical elements, designed by computer optimization techniques, can provide high coupling efficiencies between components in optical communications systems, and can be reproduced accurately in large numbers by the same technology employed to make microcircuits. This applications‐led development was for optimized f/0.48 Fresnel lenses to couple light from arrays of semiconductor lasers into monomode optical fibers. The lenses were fabricated as four phase level structures in fused quartz using electron‐beam lithography and reactive ion etching. The low f number needed to match between the laser and fiber numerical apertures required 0.2 μm feature sizes in the outer region of the lenses etched 2.1 μm deep. Effective use was made of focused ion beam etching and imaging to obtain cross sections of these high aspect ratio structures during process development. Differing lens designs have achieved 34% and 50% coupling efficiencies between 30° full width half peak 1.55 μm lasers and cleaved, monomod...

Glasses in the systems MoO3-P2O5-Ag2O and MoO3-P2O5-K2O were investigated and general areas of composition for good glass formation were determined by X-ray diffraction methods. Temperature coefficients of electrical resistivity and linear expansion were determined for the glasses along with density, durability, and other thermal characteristics. Resistivity of the glasses was effectively reduced by the addition of Ag2O.