Contrast mapping and evaluation for electronic X-ray images on CRTdisplay monitor

Simple chest X-rays on film are the most common type of image in medical diagnosis. However, amongst the various types of medical X-ray images, they require the highest level of display quality due to the fact that the body structures they capture on film have varying degrees of permeability to X-rays. Conventional high-definition digital display technology has not always been able to match the quality of such film images. This has been a major impediment against progress toward the complete digitization of simple chest X-rays. The intent of this paper is to examine that, when applied to medical diagnosis of chest X-rays, super-high-definition (SHD) images (digital images with resolution exceeding that of HDTV) are capable of producing a level of quality of diagnostic accuracy on a par with conventional film images. The authors start out by seeking out the overall transmission characteristics of a system that uses digital radiography and a film digitizer to digitize images. They then derive gray-scale transform characteristics based on the luminance linear method for approximating, as closely as possible on a CRT, film images on a light box that have wide dynamic range and high luminance. Finally, the authors present the results of image evaluation experiments using high-definition CRT monitors. These results indicate that conventional film images and those on super-high-definition CRT monitors have nearly the same quality. They also show that the contrast mapping selected by radiologists and theoretical luminance linear characteristics were almost the same except in low-luminance regions. The authors also discuss radiologists' comments on CRT monitors after they participated in the evaluation experiment     

Interface reactions between glass melts containing transition metal oxides and ferrites

The interface reactions between SiO₂-PbO-MO melts (M = Fe, Mn, Zn and Ni) and Mn-Zn and Ni-Zn ferrites were studied using electron probe microanalysis and X-ray diffraction. Ni ions in the glass melt containing NiO were localized at the interface between the glass and Mn-Zn ferrite. The Ni-rich layer was also detected at the interface between NiO containing glass melt and Ni-Zn ferrite; the composition of this layer was thought to be close to NiFe₂O₄. Pb₈NiSi₆O₂₁ crystal was deposited as the product of the reaction with the glass melt and Mn-Zn ferrite at 700 °C. As compared with Mn-Zn ferrite, no reaction products were formed in Ni-Zn ferrite at various temperatures. The dissolution length of Mn-Zn ferrite in SPN5 glass melt was found to be smaller than for other melts, and it is concluded that the NiO-rich layer at the surface of the ferrite is chemically very durable to the glass melts.     

Biodegradation of low-density polyethylene,polystyrene, polyvinyl chloride,and urea formaldehyde resin buried under soil for over 32 years

The biodegradation of several polymers that had been buried under soil for over 32 years was examined. No evidence of biodegradation was found for polystyrene, polyvinylchloride, and urea formaldehyde resin. A remarkable degradation was indicated for low density polyethylene thin films which were directly in contact with soil. Severely degraded parts of the film is characterized by whitening. Many small holes were recognized on the surface of the whitened part. The whitened part is specific for the growth of hyphae. FT-IR spectra of the whitened part showed a characteristic band in the vicinity of 1640 cm^?1 which was assigned to the stretching vibration of C?C bond. Although the part which was not in contact with soil was clear, it also showed evidence of degradation from the presence of carbonyl band in FT-IR. It was suggested that the degradation of the clear part is due to the usual thermo-oxidative process, while the degradation of the whitened part is due to the biotic process. © 1995 John Wiley & Sons, Inc.     

1.49-/spl mu/m-band gain-shifted thulium-doped fiber amplifier for WDM transmission systems

This paper describes in detail the amplification characteristics of gain-shifted thulium-doped fiber amplifiers (GS-TDFAs) operating in the 1480to 1510-nm wavelength region (1.49-/spl mu/m S-band) for use in wavelength-division-multiplexing (WDM) systems. Gain shifting of a TDFA, which normally has a gain band at 1.47 /spl mu/m (S/sup +/-band), is achieved by two types of dual-wavelength pumping: (1) 1.05 and 1.56 /spl mu/m or (2) 1.4 and 1.56 /spl mu/m. The main pump source at 1.05 or 1.4 /spl mu/m creates population inversion between /sup 3/F/sub 4/ (upper laser level) and /sup 3/H/sub 4/ (lower laser level), while the auxiliary pump source at 1.56 /spl mu/m reduces the average fractional inversion down to approximately 0.4, which is a desired level for gain shifting. We show experimentally that the former provides a low internal noise figure (<4 dB) due to high fractional inversion at the input end of a thulium fiber, while the latter provides a very high optical efficiency but a higher internal noise figure (/spl sim/5 dB) due to the lower fractional inversion at the input end. These characteristics were verified by numerical simulation based on a comprehensive rate equation modeling. We demonstrated a 1.4- and 1.56-/spl mu/m laser-diode-pumped GS-TDFA with an optical efficiency of 29.3% and high output power of +21.5 dBm. Gain flatness and tilt control were also investigated. These results strongly confirm the feasibility of using GS-TDFAs in practical ultralarge-capacity WDM networks.     

Microwave wideband tunable oscillators using coherent arrays of Josephson junctions

Coherent microwave radiation from arrays containing up to 100 indium microbridges has been directly detected. As expected the power scales as N²and the linewidth as 1/N for an array containing N junctions. Design criteria and fabrication methods for these arrays are discussed.     

Thermoelectric power of soft carbons between 4.2 and 280 K in relation to phonon drag effect

The thermoelectric power of soft carbons heat-treated to temperatures between 1700 and 3000°C was investigated between 4.2 and 280K. It was confirmed by X-ray and magnetoresistance measurements that the layer ordering was turbostratic for the samples heat-treated below 1900°C and it was graphitic for the samples heat-treated above 2100°C. The turbostratic specimens show a positive thermoelectric power which increases almost linearly with temperature. The graphitic specimens show a negative peak in the range between 20 and 35 K in the thermoelectric power versus temperature relationship. The temperature dependence of the thermoelectric power for these specimens can be classified into two distinct types in terms of heat treatment temperature. However, turbostratic specimens show no negative peak. The negative peak observed for graphitic specimens can be related to the phonon drag effect due to the coupling between carriers and long wave-length in-plane phonons, which is explained by the theory of phonon drag effect in graphite developed by Sugihara.     

A practical method of measuring scattering characteristics of apyramidal absorber

A free-space, standing-wave technique at oblique incidence is studied as a method of measuring the scattering characteristics of a pyramidal or wedge-shaped absorber. Using this method, the standing-wave ratio in front of the sample from waves with electric fields of equal amplitude are scattered in three different directions, and their scattering angles are easily measured over a wide range of frequencies and angles of incidence. No special measuring apparatus or complicated procedures are required with this method. It is found that the standing-wave ratio around 1.1 (magnitude of the scattering coefficient=0.04762) is less than ±20% in terms of scattering coefficient for incident angles ranging from 0° to 80°. The error in the scattering angle is less than 4° for the 0° scattered wave and less than ±3° for all other scattering angles