Showing papers by "Korea University published in 1992"

Ischemia of the endolymphatic sac.

Abstract: A decrease in vascular density in the endolymphatic sac was suspected as a factor in the pathogenesis of endolymphatic hydrops in Meniere's disease. The present study was undertaken to explore this possibility by cutting the posterior meningeal artery and the sigmoid sinus above and below the external aperture of the vestibular aqueduct or by incision of the dura adjacent to the sinus in 18 guinea pigs. The lesions in the sac were greater in the segmental ablation of the artery and sinus and were consistently associated with the development of endolymphatic hydrops. Among the lesions shown in the sac epithelia, the intermediate portion was most often and most severely affected with a decrease in rugose formation and a flattening of the tall epithelial cells or replacement of epithelial cells by squamous type cells. A high correlation between the lesions in the intermediate portion and occurrence of hydrops suggests that the intermediate portion plays a greater role in the pathogenesis of endolymphatic hyd...

Thermo‐ and photochromic dyes: Spiro(indolinebenzopyrans). 2—detailed assignment of the 1H NMR spectra and structural aspects of the closed form of 1,3,3‐trimethylspiro(indoline‐2,2′‐benzopyrans)

Abstract: The proton NMR assignments for a series of 12 thermo- and photochromic 1,3,3-trimethylspiro(indoline-2,2′-benzopyrans) dyes is reported. All of the protons in the dye molecule were assigned through a combination of homonuclear decoupling experiments and correlation spectroscopy. The relative stereochemistry of the indolino gem-dimethyl groups was assigned so that, for the S-epimer, the pro-R methyl was found to resonate at 1.24 ppm while the pro-S methyl appeared at 1.37 ppm for compound 1.

What is TSC

Abstract: The technical background for the thermally stimulated current (TSC) technique is presented. The effect of metal polymer contacts on the TSC method is discussed. The transitions in amorphous polymers are described. The dynamic properties of polyethylene using TSC method are given. >

Characterization of the cytokeratins of human colonic, pancreatic, and gastric adenocarcinoma cell lines.

Abstract: Summary Cytokeratin-type intermediate filaments are a polygenic family of insoluble proteins that vary according to cell of origin and have been proposed as potentially useful markers of differentiation in epithelial malignancies. Because gastrointestinal malignancies resemble each other in their expression of many soluble antigens, we compared the cytokeratins of seven colonic, three gastric, six pancreatic, and one duodenal carcinoma cell lines, and one colon villous adenoma cell line. Cytokeratins were characterized by one- and two-dimensional gel electrophoresis, immunoblotting, and immunocytochemistry. These cell lines expressed combinations of cytokeratins 7, 8, 18, and 19, which are typical of the “simple” epithelial pattern found in normal ductal and glandular tissues of the gastrointestinal tract. However, pancreatic carcinoma cell lines expressed additional cytokeratins that are normally found in stratified squamous epithelium and epidermoid (squamous cell) carcinomas. These additional cytokeratins consisted of cytokeratin 16 in all six cell, lines and cytokeratins 4, 13, and 16 in one cell line. These results suggest that cytokeratin patterns represent stable markers that may aid in distinguishing gastrointestinal malignancies.

Geochemistry and genesis of hydrothermal Au-Ag-Pb-Zn deposits in the Hwanggangri mineralized district, Republic of Korea

Abstract: The Hwanggangri mineralized district within the Ogcheon metamorphic belt of the southern Korean peninsula contains more than 60 W-Mo- and Cu-Pb-Zn(-Au-Ag)-bearing metallic ore occurrences and lesser fluorite and talc occurrences related to intrusion of Late Cretaceous (83-90 Ma), I-type and magnetite series granites. Fissure-filling veins in the district differ in mineralogy with distance from the granites: W-Mo vein deposits are located within or near (<500 m) the granites, whereas Cu-Pb-Zn vein deposits occur up to 5 km from the granites. The Geumsil and Daehyun Au-Ag-Pb-Zn mines are unique and represent the most distal deposits in the district. They consist of quartz-carbonate veins which contain economic concentrations of gold (3 g/t) and silver (250 g/t) in addition to abundant base metal sulfides (6 wt % Pb + Zn). Study of these Au-Ag-enriched mines provides a key to understanding ore-forming processes in the outer portions of a very large, batholith-driven hydrothermal circulation system.Phase equilibria, fluid inclusions, and stable isotopes indicate that ore deposition was the result of interaction of progressively less evolved meteoric waters with earlier, highly evolved meteoric waters. Early Fe sulfide mineralization occurred at temperatures of 380 degrees to 310 degrees C from fluids (delta 18 O = 10-12ppm) whose chemistry was controlled dominantly by reactions with granite and carbonate-bearing host rocks. Main base metal-Au-Ag mineralization occurred at temperatures of 250 degrees to 210 degrees C from fluids (delta 18 O = 6-7ppm) whose chemistry changed rapidly as a result of fluid unmixing and cooling. Late, postore carbonates were deposited at temperatures of 250 degrees to 165 degrees C from fluids whose stable isotope compositions (delta 18 O = 1-4ppm; delta D = -89ppm) and salinities (<3 wt % NaCl) reflect increasing meteoric water dominance.The most intriguing result of our studies is that gold deposition occurred from fluids whose chemistries were controlled dominantly by granites (and wall rocks) at temperatures well below magmatic conditions (250 degrees C) at great distances from the intrusion. The occurrence of increased gold and silver grades in these distal areas bodes well for increased exploration for Au-Ag-Pb-Zn deposits at relatively great distance from granite batholiths.

Identification of Hantaan virus-related structures in kidneys of cadavers with haemorrhagic fever with renal syndrome.

Abstract: The etiologic agent of haemorrhagic fever with renal syndrome (HFRS), Hantaan virus, was first isolated in 1976. Since then numerous Hantaan-like viruses have been isolated and five serotypes of Hantavirus have been recognized. Serological studies indicate that these viruses are globally distributed, with each serotype occurring in specific areas. Hantaan virus has been intensively studied antigenically, biochemically, and genetically. However there is still a paucity of information on the pathogenesis of Hantaan virus in the human host. In this paper, we report the detection by thin section immune electron microscopy of the occurrence of numerous dense precipitates, typical inclusion bodies, a surface antigen layer, as well as Hantaan virion-like structures in the kidneys of patients that died during the acute phase of HFRS. These findings may shed some light on understanding the pathogenesis of HFRS in target organs most affected by the disease, such as the kidneys.

An investigation into the adequacy of three IRT models for data from two EFL reading tests

Abstract: Although item response theory (IRT) is being applied increasingly in the development and use of language tests, questions about the dimensionality of specific sets of test scores and the applicability of specific IRT models to these test scores often go unaddressed in such applications. Desirable properties of IRT that have been demonstrated for measurement in general would appear to hold equally for language testing in particular (Henning 1987a, Theunis-

Application of arsenopyrite geothermometry and sphalerite geobarometry to the Taebaek Pb-Zn(-Ag) deposit at Yeonhwa I mine, Republic of Korea

Abstract: The Taebaek Pb-Zn(-Ag) deposit of the Yeonhwa I mine, Republic of Korea, occurs in a broadly folded and reverse-faulted terrain of Paleozoic sedimentary rocks: the Taebaeksan basin. The orebodies consist of several thin tabular orebodies of hydrothermal replacement type where they are hosted by carbonate rocks. The Pb-Zn(-Ag) mineralization can be divided into four distinct stages based upon the mode of occurrence of ore minerals, ore textural relationships and their composition. Based on temperatures inferred from arsenopyrite compositions by means of electron microprobe and fluid inclusions, the estimated temperatures for the stages I, II, III and IV reach 330 to 350 °C, 270 to 340 °C, 230 to 250 °C, and <220 °C, respectively. The sulphur activity (atm) of ore formation at the Taebaek deposit was estimated for each stage as 10−11 to 10−11.5, 10−9.5 to 10−13, 10−13.5 to 10−15, and <10−15, respectively. Even though application of sphalerite geobarometry is problematic because of the absence of good mineral assemblages, sphalerite coexisting with pyrite but not with pyrrhotite was used to estimate the minimum mineralization pressure (about 1 kbar).

Nuclear magnetic resonance of 209Bi in a BiVO4 single crystal

Abstract: Nuclear magnetic resonance spectra of 209Bi(I=9/2) in the ferroelastic BiVO4 single crystal has been investigated by employing a wide-line Varian spectrometer. Only three lines due to a large quadrupole interaction were measured at a fixed frequency of 6 MHz in the principal planes at room temperature. From the experimental data the quadrupole coupling constant E2qQ/h=79.2+or-0.1 MHz and asymmetry parameter eta =0.70+or-0.01 are determined; however, these values turn out to be quite different from the previous report obtained with a ceramic sample at liquid-nitrogen temperature. The principal axes of the electric field gradient tensor are determined for the first time, the x, y and z axes being the crystallographic c+25 degrees , a+25 degrees , and b axes, respectively. Thes directions are discussed in terms of the Bi-O bonds in the Bi-O polyhedra.

High-pressure Raman study of fullerite C60

Abstract: High-pressure Raman spectra of fullerite, a solid form of C 60 , were measured at pressures up to a 4 GPa and room temperature. A change of slope (dv/dP) of the frequency-pressure plots for the A g pentagonal pinch mode and the A g breathing mode was observed at 1.3 GPa, where a solid-solid phase transition might occur. The phase transition was observed to be irreversible. The pressure dependence of the Raman mode frequency and the phase transition are discussed in terms of an orientational ordering transition in fullerite

Fermentation of prefermented and extruded rice flour by the lactic acid bacteria from sikhae

Abstract: The acid‐ and flavor‐forming properties of Lactobacillus plantarum and Leuconostoc mesenteroides isolated from Sikhae, a Korean traditional lactic acid fermented fish product, were examined and compared to those of Lactobacillus casei and Lactococcus lactis subsp. diacetylactis DRC3. The effects of prefermentation of rice flour in solid‐state with Bacillus laevolacticus and Saccharomyces‐cerevisiae, extrusion cooking and addition of soymilk as the substrate of lactic acid fermentation vere tested. Extrusion cooking and prefermentation of rice increased the soluble solid and sugar contents before malt digestion. The amount of sugar consumption during lactic fermentation varied with the type of bacteria. Leuconostoc mesenteroides(sikhae) and Lactobacillus plantarum(sikhae) increased up to 6 times of original cell number by 24 hrs of fermentation in rice + soymilk substrate, but Lactococcus lactis decreased in the same substrates. The final pH of the cereal lactic beverage was in the range of 3.4 ‐ ...

Calcified gastric carcinoma: CT findings

Abstract: The computed tomographic (CT) findings of 13 cases of calcified gastric carcinoma were analyzed retrospectively Eleven cases were confirmed as a mucinous adenocarcinoma by surgery (three cases), or endoscopic biopsy (eight cases) Two cases were diagnosed as adenocarcinoma by endoscopic biopsy In all cases the calcifications were of the punctate or miliary shape and the size varied from 1-3 mm in diameter The calcifications were located in the thickened gastric wall in all cases, and were seen in metastatic lesions such as lymph nodes and the liver in two cases In 10 cases, some tumor portions showed lower attenuation number than that of the muscle on CT scans, and corresponded to mucin pool in tumor portions histologically Twelve cases were in inoperable advanced stage

Reaction of (E)-O-Arylbenzaldoximes with Sodium Methoxide in Methanol. Effect of Leaving Group upon Nitrile-Forming Transition State

Abstract: Reactions of (E)-O-arylbenzaldoximes 1-3 with MeONa-MeOH have been studied kinetically. The reactions proceed via competing E2 and S N Ar reactions, in which the first step is rate-determining. Although the reactions were strongly influenced by the electronic effect of the β- and O-aryl substituents, they were insensitive to the steric effect of the O-aryl group, except that the S N Ar reaction was retarded by the CF 3 group of 2. For eliminations from 1-3 promoted by MeONa-MeOH, the k H /k D value increased and the Hammett p value decreased with better leaving groups

Exact solutions for a mode of the electromagnetic field in a resonator with time-dependent characteristics of the internal medium

Abstract: The problem of quantization of the electromagnetic field inside a resonator filled with a dielectric medium with time-dependent characteristics in the presence of the external alternating current is studied. The exact propagator and the coherent and Fock's states are obtained for a quantum oscillator with time-dependent frequency linearly coupled via momentum with external current. Delta-pulse excitation of the medium is considered as an example.

Feeding and oviposition preferences and demography of rice weevil (Coleoptera : Curculionidae) reared on mixtures of brown, polished, and rough rice

Abstract: In four mixed media composed of (1) brown and polished rice, Oryza sativa L., (2) brown and rough rice, (3) polished and rough rice, and (4) brown, polished, and rough rice, feeding and oviposition of the rice weevil, Sitophilus oryzae (L.), were observed. In all media, the weevil rarely exploited rough rice. The rice weevil fed on brown rice more frequently than on polished rice, but did not concentrate on brown rice in the media containing both brown and polished rice. The feeding preference index for brown rice over polished rice was ≍1.9. Females laid more eggs on brown rice than on polished rice. In the media containing both brown and polished rice, females laid eggs exclusively on brown rice; the preference index for brown rice over polished rice was ≍19.3. Mortality of the weevil during development in the medium without brown rice was significantly higher than in the media with brown rice. Life table statistics for the weevil in the four media showed that brown rice was the critical factor determining population development. Thus, the weevil's strong oviposition preference for brown rice allows it to maximize its fitness when feed with a variety of resources of different qualities. The relative impact of oviposition versus feeding preferences of the weevil on its reproductive success is discussed.

A High-speed Thinning Processor For Character Recognition System

Abstract: A modified thinning algorithm is proposed and its validity demonstrated. Experimental results show that this modified algorithm preserves the connectivity and the end points, which are critical requirements in a character recognition system. A flexible thinning processor has been integrated and interfaced with an IBM PC AT/386 and been tested for variable image widths from 25 to 40 b. For a 38*38 image and 1.5-kb data, completion of thinning requires 2.8 ms. It is shown that processing speed is limited only to the propagation delays of logic gates, since the input image continuously enters the processor without a control signal. Experimental results confirm that this modified algorithm and processor are effective in image processing as well as character and fingerprint recognition. >

Antigenic localities in the tissues of Paragonimus westermani by developmental stages using immunogold labeling method

Abstract: In order to observe the antigenic localization in the tissues of Paragonimus westermani of developmental stages, immunogold labeling method was applied using serum of the cats which were infected with isolated metacercariae from Cambaroides similis. The sectioned worm tissues from each developmental stage were embedded in Lowicryl HM 20 medium, stained with infected serum IgG and protein A gold complex (particle size: 12 nm) and observed by electron microscopy. In the young adult worm tissue of 4 weeks after infection with metacercariae, the gold particles were specifically concentrated on the tegumental syncytium and cytoplasm of the tegumental cells as well as the secretory granules in the parenchymal tissue. The antigenic materials in the adult worm tissue were specifically concentrated on the secretory granules in the parenchymal tissue, the cytoplasm between granules in the vitelline gland and the epithelial lamella in the lumen of the caecum.

The law of the iterated logarithm for local time of a Lévy process

Abstract: Let {X t } be a one-dimensional Levy process with local timeL(t, x) andL *(t)=sup{L(t, x): x ∈ ℝ}. Under an assumption which is more general than being a symmetric stable process with index α>1, we obtain a LIL forL*(t). Also with an additional condition of symmetry, a LIL for range is proved.

An expert system to facilitate the uniform administration of justice in criminal cases

Abstract: As an attempt to facilitate uniform sentencing in the criminal justice system of the Korean Judiciary, we have developed an expert system which determines sentences for traffic (vehicular) offenses described in chapter 268 of the Korean Criminal Code. Through interviews and discussions with judges, we have selected the main factors based upon which respective sentence is determined. Next, on that ground we have established key facts of each main factor, and then have embodied the reasoning process in imposing a sentence. In addition to judges, professional knowledge and experience of medical doctors, police officers, and insurance experts are reflected in this system. The expert system developed is a kind of factor comparison model and normative model.