SUMMARYOn 79 ECG tracings obtained from 31 uremic patients, the influence of serum Ca, Na, and K concentrations on the QT duration in ECG was analyzed by multiple regression technique. It was found that Ca and K had negative and Na had a positive effect on QT duration, although only the effect of Ca was reaching the statistically significant level. Since serum electrolytes had correlations with each other, they were orthogonalized and tested for significance once again. Still Na and K did not reveal significant influences by this procedure. However, the effects of Na and K on QT duration were as the same direction and magnitude as reported in older literatures.In the course of orthogonalization it was found that Ca and Na had negative influences on K. It seems that this fact presents a sound basis for the therapeutic use of Ca and Na salts in hyperpotassemia. Additional Indexing Words: QT ratioCa therapy in hyperpotassemia Na therapy in hyperpotassemia Multiple regression analysis Orthogonalization T duration has as its components, the propagation of depolarization wave, membrane action potential duration, and propagation of repolarization wave.Each of these components is influenced by the heart rate and also by the electrolyte concentrations in the surrounding medium. So, it is natural that, beside the influence of the heart rate on QT duration in ECG,1) the effect of alterations in plasma Ca concentration on it has been one of the earliest findings in clinical electrocardiography.2) In 1948 Nadler et al. reported that QT duration was inversely correlated with the serum K concentration in patients with diabetic acidosis.3) This observation was not confirmed by several authors, and some also noticed that QT duration in cases of hypopotassemia

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Two types of precisely molded fiber optic connectors have been developed. They are a cylindrical ferrule connector for a single fiber and a five‐fiber array connector for a tape fiber. The connectors are made by using a transfer molding technique with a silica‐filled thermosetting epoxy resin. The resin has low pressure and high melt‐flow characteristics, high dimensional accuracy, and high stability. The single fiber connector consists of a pair of plastic molded ferrules, a slitted alignment sleeve, and a plate spring. A fiber is inserted into a ferrule capillary and is fixed with adhesive. Then the fiber end face positioned in the center of the ferrule is polished to have a mirror surface. The five‐fiber connector consists of a couple of precisely molded ferrules, two alignment pins, and a plate spring. The five‐fiber ribbon is inserted into fiber receiving capillaries, of the ferrule, and fixed with adhesive. The fiber end faces on the ferrule mating face are polished to have a mirror face. In order to realize a low‐loss connection, the alignment pin holes and five‐fiber positioning capillaries on the ferrule mating face must be molded precisely. Various kinds of reliability tests on the connectors were conducted. All the results obtained proved that the connectors have entirely satisfactory properties for practical use. The connectors are now widely used in an optical fiber subscriber network.

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A plastic molded multifiber connector which can splice fiber ribbons, has been widely introduced into fiber optic subscriber networks.T h e connector is made by a precision transfer molding method, employing a ultrahigh precision multi-V-grooves mold. Its dimensional accuracy is s o high that single mode four fiber ribbons are spliced with average loss of 0.3 dB using refractive index matching oil.The connector is mainly used for a factory-mounted preconnectorized optical fiber ribbon cable which has up to 1000 fibers in a cable.Recently the multifiber plastic connector has been used in a optical filter for fiber ribbons, in a mechanical switch for fiber ribbons and in a high speed mechanical switch.