Reproducibility of nerve fiber layer thickness measurements using optical coherence tomography

PURPOSE: Optical coherence tomography (OCT) is a new technology that uses near-infrared light in an interferometer to produce approximately 10-microns resolution cross-sectional images of the tissue of interest. The authors performed repeated quantitative assessment of nerve fiber layer thickness in individuals with normal and glaucomatous eyes, and they evaluated the reproducibility of these measurements. METHODS: The authors studied 21 eyes of 21 subjects by OCT. Each subject underwent five repetitions of a series of scans on five separate occasions within a 1-month period. Each series consisted of three circular scans around the optic nerve head (diameters, 2.9, 3.4, and 4.5 mm). Each series was performed separately using internal (fixation with same eye being studied) and external (fixation with contralateral eye) fixation techniques. The eye studied and the sequence of testing were assigned randomly. RESULTS: Internal fixation (IF), in general, provides a slightly higher degree of reproducibility than external fixation (EF). Reproducibility was better in a given eye on a given visit than from visit to visit. Reproducibility as measured by intraclass correlation coefficients were as follows: circle diameter (CD), 2.9 mm, 0.51/0.57 (normal/glaucoma) (IF), 0.43/0.54 (EF); CD, 3.4 mm, 0.56/0.52 (IF), 0.43/0.61 (EF); CD, 4.5 mm, 0.53/0.43 (IF), 0.42/0.49 (EF). CONCLUSIONS: Nerve fiber layer thickness can be reproducibly measured using OCT. Internal is superior to external fixation; each circle diameter tested provides adequate reproducibility.     

Serial MRI findings of benign poliomyelitis

Clinical and electrodiagnostic evaluations were performed in 25 patients with electric burns who were injured 2 to 13 years before the study. Abnormal motor nerve conduct findings were detected in 12 of the patients. In nine patients, abnormalities were observed in more than one nerve. There was a positive relation noted between age and nerve lesions. Weakness was the most prominent clinical finding.     

Microtexture and magnetoresistance of glass-like carbons

Microtextures of glass-like carbons commercially available were investigated through scanning electron microscopy and measurement of their magnetoresistance. A field-emission electron gun type SEM, which is characterized by a specimen chamber equipped in its objective lens, was operated with the acceleration voltage of 2 kV and high fidelity observations were thereby achieved with a resolving power of 2 nm. All the specimens exhibit granular microtextures with the mean grain diameter spanning 6–13 nm. The mean grain diameter correlates to the mean crystallite size L_a(110) determined by the X-ray powder diffractometry. The density of each sample calculated by using the mean diameter and the X-ray parameters reproduces well its catalog value. Negative magnetoresistance was observed just for the specimens whose average grain sizes are not smaller than 7.3 nm. The crystallite size _La(110) of the specimen whose grain size shows the minimum value for appearance of negative magnetoresistance is estimated to be 2.7 nm. The absolute value of negative magnetoresistance under a constant magnetic field increases with increasing the average grain size.     

Requirements for modeling of a snowdrift

In an experiment of a model snowdrift formed behind each of two model snow fences, which are the same in shape but different in size, the independence of the wind speed ratio between them from their length ratio was observed. This phenomenon can be explained not by the Froude number, but by the effect of wakes behind an obstruction and movement characteristics of snow particles. The wind speed ratio and the duration of a storm in which the model snowdrifts of glass beads and activated clay particles become similar to each other, were examined. It follows from the result that the friction speed ratio is equal to the ratio of the threshold friction speed of both model snow particles, and the ratio of storm duration can be calculated by comparing the volume of both model snowdrifts. This result suggests strongly that the same relationships hold between the model and the prototype snowdrift.     

Temperature-Stable lead-Relaxor-Based Ceramic Dielectrics with Chemical lnhomogeneity

Matrix grains of Pb-relaxor ceramics with chemical inhomogeneity, showing the so-called core-shell structure already reported for BaTiO₃-based X7R ceramics, were obtained by a controlled sintering process in a MgO-excess and PbO-excess PMN-PMW-PT system. Multilayer ceramic capacitors exhibiting the X7T specifications were then fabricated from the 8 mol% MgO excess and 4 mol% PbO excess powder. Their chemical inhomogeneity was stable, showing a decrease of capacitance of only 2.9% after an 800-h aging test.     

Trimethylamine-sensing mechanism of TiO2-based sensors 1. Effects of metal additives on trimethylamine-sensing properties of TiO2 sensors

The effects of metal additives on the trimethylamine (TMA)-sensing properties of TiO₂ have been investigated. The sensitivity to TMA is enhanced by the addition of 0.5 wt.% Ru, 2.0 wt.% In or 0.5 wt.% Au, whereas the addition of 0.5 wt.% Pt, 1.5 wt.% Pd or 1.5 wt.% Rh results in a decrease in the sensitivity. It is also revealed that the effect of each metal varies with the amount added. From the variations in resistance both in air and in 300 ppm TMA with the added amount of each metal, the roles of the metal additives are discussed.     

Development of a live-line partial-discharge detection method for XLPE-insulated copper wire-shielded cable using a “yoke coil”

This paper describes a new partial-discharge detection method for an XLPE-insulated copper wire-shielded cable line using a “yoke coil.” Partial discharges are measured with the yoke coil which detects the azimuthal component of the current flowing through the copper wires wound on an outer semiconducting layer with a given angle against the axial direction of the cable. The highest detection sensitivity of 2 pC has been achieved at a frequency range of 5 to 20 MHz using a 77-kV 100-mm² model cable line (200 m in length). It was confirmed that the partial discharge caused by an artificial defect has successfully been detected using the proposed method. In the PD measurement for an actual 77-kV XLPE-insulated live line, the detection sensitivity was 10 pC.