Showing papers by "Yonsei University published in 1981"

Magnetic properties and the crystallization of amorphous Fe 75.4 B 14.2 Si 10.4

Abstract: The amorphous state of ferromagnetic ${\mathrm{Fe}}_{75.4}$${\mathrm{B}}_{14.2}$${\mathrm{Si}}_{10.4}$ and its crystalline phases after crystallization have been studied by M\"ossbauer spectroscopy and magnetic-moment measurements. The average hyperfine field ${H}_{\mathrm{hf}}(T)$ of the amorphous state shows a temperature dependence of $\frac{[{H}_{\mathrm{hf}}(T)\ensuremath{-}{H}_{\mathrm{hf}}(0)]}{{H}_{\mathrm{hf}}(0)=\ensuremath{-}0.30{(\frac{T}{{T}_{c}})}^{\frac{3}{2}}\ensuremath{-}0.16{(\frac{T}{{T}_{c}})}^{\frac{5}{2}}}$ for $\frac{T}{{T}_{c}}l0.7$, indicative of spin-wave excitation. The quadrupole splitting just above ${T}_{c}$ is 0.46 mm/s, whereas the average quadrupole shift below ${T}_{c}$ is zero. The Curie and crystallization temperatures are determined to be ${T}_{c}=701$ K and ${T}_{x}=827$ K, respectively, for a heating rate of 11 K/min. The final products of crystallization are found to be ${\mathrm{Fe}}_{2}$B and a Fe-18.1 at.% Si alloy. The saturation magnetic moment of the amorphous state extrapolated to 0 K is found to be $\frac{2.05{\ensuremath{\mu}}_{B}}{\mathrm{Fe}}$ atom. The magnetization of the amorphous phase decreases more rapidly with reduced temperature than those of crystalline ferromagnets. This kind of rapid decrease can be described in terms of either a distribution of exchange interactions in the amorphous phase or high metalloid contents.

n-Dimensional representations of the unified field tensor* g λν

Abstract: For the first time Hlavatý represented the tensor*gλv, defined by (15a), in terms of the unified field tensorg λμ in the space-timeX 4. Recently, the representations of* g λv in terms ofg λμ in two- and three-dimensional generalized Riemannian space were obtained by Chung. The purpose of the present paper is to obtain the generalized representations of* g λv in terms ofg λμ in a generalizedn-dimensional Riemannian spaceX n.

Ascending spinal pathways mediating somato-cardiovascular reflexes

Abstract: The influences of spinal somatic afferent pathways upon cardiovascular parameters were studied in anesthetized and conscious dogs. Previous studies on anesthetized cats indicated that activation of somatic A afferent fibers results in a depressor response mediated by ascending spinal pathways in the dorsolateral funiculus (DLF). Additional activation of somatic C afferent fibers results in a pressor response mediated by pathways in the region of the dorsolateral sulcus (DLS). In anesthetized dogs sympathetic-mediated cardiovascular responses to somatic afferent stimulation are found to be conducted in the DLS. To test the possibility that these afferent pathways may mediate cardiovascular responses to exercise, dogs instrumented for blood pressure and heart rate monitoring were trained to run on a treadmill on all 4 legs and on their hindlegs only. Lesions of the DLS and a portion of the DLF significantly altered heart rate responses to treadmill running on all 4 legs. These data suggest that somato-autonomic reflexes participate in the cardiovascular adjustments which occur during exercise.

Parasitic amebae in Korea.

Abstract: This review dealt with biology, host-parasite relationship, symptomatology, epidemiology, diagnosis, treatment of Entamoeba histolytica infection and free livng amoeba.

Prevalence of exclusive and extended breastfeeding among rural Korean women.

Abstract: This paper uses the survey findings of rural Korean women from 7 nonrepresentative areas from May 1981-August 1981 to ascertain the prevalence of exclusive and extended breastfeeding frequency of breastfeeding and the pattern of artificial or supplementary feeding. All mothers began breastfeeding but many were immediately supplementing from the 1st month. 30% of the mothers who delivered in clinics began to supplement from the time of birth. Exclusive breastfeeding rates fall steeply with age while general extended breastfeeding rates fall slowly. Feeding rate on demand was 25.5% and more frequently among women with no past experience of breastfeeding and 74.5% of feeding was done on schedule. The most common reason given for not breastfeeding was "lack of or insufficient milk." About 10% of mothers were advised to give cows milk supplements by health personnel. Monthly supplementary feeding rates were gradually increased until the 12th month with steep curves from the 2nd-7th months. Cumulative frequency of infants having commercial weaning food reaches 20% at 9 months. (authors)

Tin Abundance of the Mesozoic Granitoids in Southern Korea

Abstract: Twenty-five Jurassic granitoids, 13 Cretaceous granitoids and 7 metamorphic rocks were analyzed for trace amounts of tin. Jurassic and Cretaceous granitoids of the general ilmenite-series terrain of the continental interior are poor in tin ranging from 0.3 to 3.3 ppm in general. Some stocks, dikes and altered granite contain 2 to 12.8 ppm Sn. The basement metamorphic rocks are also low in tin (average 1.1 ppm). These low contents may be related to the general paucity of tin ore deposits in southern Korea. The magnetite-series, Cretaceous granitoids in the Gyeongsang basin are extremely low in tin (average 0.9 ppm). No tin deposits may be expected associated with the granitoids, but Cretaceous granitoids of the continental interior are different being richer in tin than the Gyeongsang basin granitoids; those of the Taebaegsan area need to be examined in terms of the tin geochemistry.

Influence of vitamin E on the effect of vitamin A derivatives on digestive glands of rats.

Abstract: This study was designed to investigate the influence of d-α-tocopheryl acetate on the toxic effect of retinoic acid and retinoid (Ro 10-9359) on pancreaticobiliary and gastric secretion after the administration of large doses for 3 weeks to albino rats. The toxicity of retinoic acid on body weight and exocrine function, and the morphologic changes in the main digestive glands of the rat are greater than with retinoid. It is clear that vitamin E may suppress or counteract the undesirable toxic effects of retinoic acid and retinoid and appears to promote the function of the main digestive glands of rats.