Heuristic optimization in penumbral image for high resolution reconstructed image.

Penumbral imaging is a technique which uses the fact that spatial information can be recovered from the shadow or penumbra that an unknown source casts through a simple large circular aperture. The size of the penumbral image on the detector can be mathematically determined as its aperture size, object size, and magnification. Conventional reconstruction methods are very sensitive to noise. On the other hand, the heuristic reconstruction method is very tolerant of noise. However, the aperture size influences the accuracy and resolution of the reconstructed image. In this article, we propose the optimization of the aperture size for the neutron penumbral imaging.

Incident polarization angle and temperature dependence of polarization and spectral response characteristics in optical fiber couplers.

The incident polarization angle and temperature dependence of the polarization and spectral response characteristics of three different types of fiber coupler are presented. The couplers are (1) the biconicalfused- twisted-taper single-mode fiber (coupler A), (2) the asymmetric-etched-fused-taper wavelength division multiplex (coupler B), and (3) the biconical-polished polarization maintaining fiber (coupler C), respectively. It is confirmed experimentally that the polarization characteristics of couplers A and B vary greatly with temperature, but those of coupler C are independent of temperature. Also, the wavelength dependence characteristics of the power splitting ratio of couplers B and C have almost no change with temperature. However, the wavelength dependence of coupler A is greatly changed with temperature. Comparing couplers A and B, it is postulated that the sinusoidal variations of the polarization state vs the incident polarization angle are due to the stress birefringence caused by the fiber twisting when the fused fiber coupler is fabricated and packaged.

Multiple endocrine neoplasia, type 1, with pancreatic cholera.

A 20-yr-old black woman presented in 1969 with headache, amenorrhea, hyperprolactinemia, hypogonadotropism, hypogonadism, and hypercalcemia due to a chromophobe adenoma. She received 5000 rads to the sella. One year later she was found to have hyperparathyroidism due to parathyroid adenoma and three and a half glands were removed. Thirteen years later she presented with 3 months of profuse watery diarrhea, hypokalemia, hypercalcemia, hyperchloremic metabolic acidosis, and a normal anion gap. A vasoactive intestinal polypeptide-producing tumor of the pancreas was found and successfully removed, after which hypercalcemia resolved. This is an unusual case of the multiple endocrine neoplasia syndrome, type 1, being associated with a vasoactive intestinal polypeptide-oma and pancreatic cholera.

Temperature dependence of the hydrogen-diffusion constant in optical fibers.

The dependence on hydrogen pressure and temperature of the increase in absorption loss is described for a singlemode optical fiber. The hydrogen-diffusion constant for various temperatures and the activation energy in silicabased optical fibers are obtained.

Birefringence variation with temperature in elliptically cladded single-mode fibers.

A nondestructive method for measuring a beat length of stress-induced birefringent fibers is described. Using the method at 1.3-microm wavelength, the relation of the beat length in elliptically cladded fibers vs temperature is investigated. The experimental results indicate that the beat length increases almost linearly with temperature in the vicinity of room temperature. Using the measurement results, we obtain temperature at which no stress-induced birefringence occurs. Furthermore, it is indicated that the phase retardation in the stress-induced birefringent fibers changes linearly with temperature.