Showing papers by "Kyungpook National University published in 2002"

Face recognition using kernel principal component analysis

Abstract: A kernel principal component analysis (PCA) was previously proposed as a nonlinear extension of a PCA. The basic idea is to first map the input space into a feature space via nonlinear mapping and then compute the principal components in that feature space. This article adopts the kernel PCA as a mechanism for extracting facial features. Through adopting a polynomial kernel, the principal components can be computed within the space spanned by high-order correlations of input pixels making up a facial image, thereby producing a good performance.

The effect of filler loading and morphology on the mechanical properties of contemporary composites

Abstract: Statement of Problem Little information exists regarding the filler morphology and loading of composites with respect to their effects on selected mechanical properties and fracture toughness Purpose The objectives of this study were to: (1) classify commercial composites according to filler morphology, (2) evaluate the influence of filler morphology on filler loading, and (3) evaluate the effect of filler morphology and loading on the hardness, flexural strength, flexural modulus, and fracture toughness of contemporary composites Material and Methods Field emission scanning electron microscopy/energy dispersive spectroscopy was used to classify 3 specimens from each of 14 commercial composites into 4 groups according to filler morphology The specimens (each 5 × 25 × 15 mm) were derived from the fractured remnants after the fracture toughness test Filler weight content was determined by the standard ash method, and the volume content was calculated using the weight percentage and density of the filler and matrix components Microhardness was measured with a Vickers hardness tester, and flexural strength and modulus were measured with a universal testing machine A 3-point bending test (ASTM E-399) was used to determine the fracture toughness of each composite Data were compared with analysis of variance followed by Duncan's multiple range test, both at the P Results The composites were classified into 4 categories according to filler morphology: prepolymerized, irregular-shaped, both prepolymerized and irregular-shaped, and round particles Filler loading was influenced by filler morphology Composites containing prepolymerized filler particles had the lowest filler content (25% to 51% of filler volume), whereas composites containing round particles had the highest filler content (59% to 60% of filler volume) The mechanical properties of the composites were related to their filler content Composites with the highest filler by volume exhibited the highest flexural strength (120 to 129 MPa), flexural modulus (12 to 15 GPa), and hardness (101 to 117 VHN) Fracture toughness was also affected by filler volume, but maximum toughness was found at a threshold level of approximately 55% filler volume Conclusion Within the limitations of this study, the commercial composites tested could be classified by their filler morphology This property influenced filler loading Both filler morphology and filler loading influenced flexural strength, flexural modulus, hardness, and fracture toughness (J Prosthet Dent 2002;87:642-9)

Observation of B̄0 → D(*)0 pp̄

Abstract: The B meson decay modes B → Dpp and B → D*pp have been studied using 29.4 fb - 1 of data collected with the Belle detector at KEKB. The B 0 → D 0 pp and B 0 → D* 0 pp decays have been observed for the first time with branching fractions B(B 0 → D 0 pp) = (1.18 ′ 0.15 ′ 0.16) X 10 - 4 and B(B 0 → D* 0 pp) = (1.20 + 0 . 3 3 - 0 . 2 9 ′ 0.21) X 10 - 4 . No signal has been found for the B + → D + pp and B + → D* + pp decay modes, and the corresponding upper limits at 90% C.L. are presented.

Support vector machines for texture classification

Abstract: This paper investigates the application of support vector machines (SVMs) in texture classification. Instead of relying on an external feature extractor, the SVM receives the gray-level values of the raw pixels, as SVMs can generalize well even in high-dimensional spaces. Furthermore, it is shown that SVMs can incorporate conventional texture feature extraction methods within their own architecture, while also providing solutions to problems inherent in these methods. One-against-others decomposition is adopted to apply binary SVMs to multitexture classification, plus a neural network is used as an arbitrator to make final classifications from several one-against-others SVM outputs. Experimental results demonstrate the effectiveness of SVMs in texture classification.

The role of n-3 polyunsaturated fatty acids in brain: Modulation of rat brain gene expression by dietary n-3 fatty acids

Abstract: Rats were fed either a high linolenic acid (perilla oil) or high eicosapentaenoic + docosahexaenoic acid (fish oil) diet (8%), and the fatty acid and molecular species composition of ethanolamine phosphoglycerides was determined. Gene expression pattern resulting from the feeding of n-3 fatty acids also was studied. Perilla oil feeding, in contrast to fish oil feeding, was not reflected in total fatty acid composition of ethanolamine phosphoglycerides. Levels of the alkenylacyl subclass of ethanolamine phosphoglycerides increased in response to feeding. Similarly, levels of diacyl phosphatidylethanolamine molecular species containing docosahexaenoic acid (18:0/22:6) were higher in perilla-fed or fish oil-fed rat brains whereas those in ethanolamine plasmalogens remained unchanged. Because plasmalogen levels in the brains of rats fed a n-3 fatty acid-enriched diet increased, it is plausible, however, that docosahexaenoic acid taken up from the food or formed from linolenic acid was deposited in this phospholipid subclass. Using cDNA microarrays, 55 genes were found to be overexpressed and 47 were suppressed relative to controls by both dietary regimens. The altered genes included those controlling synaptic plasticity, cytosceleton and membrane association, signal transduction, ion channel formation, energy metabolism, and regulatory proteins. This effect seems to be independent of the chain length of fatty acids, but the n-3 structure appears to be important. Because n-3 polyunsaturated fatty acids have been shown to play an important role in maintaining normal mental functions and docosahexaenoic acid-containing ethanolamine phosphoglyceride (18:0/22:6) molecular species accumulated in response to n-3 fatty acid feeding, a casual relationship between the two events can be surmised.

Aberrant expression of growth differentiation factor-9 in oocytes of women with polycystic ovary syndrome.

Abstract: Polycystic ovary syndrome (PCOS) is a major cause of female infertility. Despite substantial effort, the etiology and pathogenesis of PCOS and polycystic ovaries (PCO) in women remain unknown. Recent studies in laboratory animals have documented a link between dysfunction of two oocyte growth factors, growth differentiation factor-9 (GDF-9) and bone morphogenetic factor-15 (BMP-15), and aberrant folliculogenesis. Because aberrant follicle development is a hallmark of PCOS, we wondered whether the expression patterns of these growth factors might be disrupted in PCOS and PCO oocytes. To address this issue, we compared the pattern and level of expression of GDF-9 and BMP-15 mRNA in ovaries from normal cycling (n = 12), PCOS (n = 5), and PCO (n = 7) patients. In situ hybridization studies showed that the expression of GDF-9 and BMP-15 is restricted to the oocytes in all ovaries examined. Interestingly, a decreased level of GDF-9 signal was observed in developing PCOS and PCO oocytes, compared with normal. This difference was evident throughout folliculogenesis, beginning at recruitment initiation and continuing through the small Graafian follicle stage. By contrast, there were no qualitative or quantitative changes in the expression of BMP-15 mRNA in PCOS oocytes during folliculogenesis. There were also no significant differences between normal and PCOS and PCOs in the levels of the mRNA encoding the housekeeping gene, cyclophilin. Together, these results indicate that the expression of GDF-9 mRNA is delayed and reduced in PCOS and PCO oocytes during their growth and differentiation phase. Because oocyte-derived GDF-9 is crucial for normal folliculogenesis and female fertility, we suggest that a dysregulation of oocyte GDF-9 expression may contribute to aberrant folliculogenesis in PCOS and PCO women.

Fingerprint-based remote user authentication scheme using smart cards

Abstract: An authentication system, which does not require a password table to authenticate its users, is proposed. By removing a password table, and introducing smart card and fingerprint verification, the scheme can be more secure and reliable. In addition, the scheme can withstand message replaying attack and impersonation.

Observation of Double cc ̄ Production in e + e - Annihilation at (s)~10.6 GeV

Abstract: We report the observation of prompt $J/\ensuremath{\psi}$ via double $c\overline{c}$ production from the ${e}^{+}{e}^{\ensuremath{-}}$ continuum. In this process one $c\overline{c}$ pair fragments into a $J/\ensuremath{\psi}$ meson while the remaining pair either produces a charmonium state or fragments into open charm. Both cases have been experimentally observed. We find cross sections of $\ensuremath{\sigma}[{e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}J/\ensuremath{\psi}{\ensuremath{\eta}}_{c}(\ensuremath{\gamma})]\ifmmode\times\else\texttimes\fi{}\mathcal{B}({\ensuremath{\eta}}_{c}\ensuremath{\rightarrow}\ensuremath{\ge}4\text{ }\text{ }\mathrm{\text{charged}})=({0.033}_{\ensuremath{-}0.006}^{+0.007}\ifmmode\pm\else\textpm\fi{}0.009)\text{ }\text{ }\mathrm{p}\mathrm{b}$ and $\ensuremath{\sigma}({e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}J/\ensuremath{\psi}{D}^{*+}X)=({0.53}_{\ensuremath{-}0.15}^{+0.19}\ifmmode\pm\else\textpm\fi{}0.14)\text{ }\text{ }\mathrm{p}\mathrm{b}$ and infer $\ensuremath{\sigma}({e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}J/\ensuremath{\psi}c\overline{c})/\ensuremath{\sigma}({e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}J/\ensuremath{\psi}X)={0.59}_{\ensuremath{-}0.13}^{+0.15}\ifmmode\pm\else\textpm\fi{}0.12$. These results are obtained from a $46.2\text{ }\text{ }{\mathrm{f}\mathrm{b}}^{\ensuremath{-}1}$ data sample collected near the $\ensuremath{\Upsilon}(4S)$ resonance, with the Belle detector at the KEKB collider.

Polymorphism of the DNA Repair Gene XRCC1 and Risk of Primary Lung Cancer

Abstract: DNA repair plays a critical role in protecting the genome of the cell from insults of cancer-causing agents, such as those found in tobacco smoke. Reduced DNA repair capacity, therefore, can increase the susceptibility to smoking-related cancers. Recently, three coding polymorphisms in X-ray cross-complementing group 1 (XRCC1) DNA repair gene have been identified, and it is possible that these polymorphisms may affect DNA repair capacity and thus modulate cancer susceptibility. We investigated the relationship between the codon 399 polymorphism in XRCC1 gene and lung cancer risk in male smokers. The study population consisted of 192 lung cancer patients and 135 healthy controls. The distribution of XRCC1 genotypes was not significantly different between cases and controls. When the cases were categorized by histological type, however, the presence of at least one Gln allele was associated with a significant increased risk for squamous cell carcinoma [crude odds ratio (OR) = 1.77, 95% confidence interval (CI) = 1.06-2.93 and adjusted OR = 1.66, 95% CI = 0.99-2.79]. The risk for the disease increased as the number of Gln alleles increased (Arg/Gln genotype: adjusted OR = 1.45, 95% CI = 0.84-2.5; Gln/Gln genotype: adjusted OR = 3.26, 95% CI = 1.17-9.15). When the subjects dichotomized by cigarette consumption into two pack-year groups ( 40 pack-years), the Gln allele was associated with an increased risk for squamous cell carcinoma only in the group of individuals having < or =40 pack-years of smoking (Arg/Gln genotype: adjusted OR = 1.48, 95% CI = 0.78-2.8; Gln/Gln genotype: adjusted OR = 5.75, 95% CI = 1.46-22.69). These results suggest that XRCC1 codon 399 polymorphism may be an important genetic determinant of squamous cell carcinoma of the lung in persons with lower degrees of cigarette use.

Influence of calcium hydroxide intracanal medication on apical seal.

Abstract: Aim The aim of this study was to determine the influence of calcium hydroxide intracanal medication and various techniques for its removal on the sealing ability of gutta-percha root fillings with a zinc oxide-eugenol sealer. Methodology Eighty extracted mature human mandibular molar roots were divided into three groups of similar root-canal configuration. Calcium hydroxide paste was made by mixing calcium hydroxide powder with distilled water at a powder to liquid ratio of 1:1.25. After root canals were prepared and enlarged to a minimum of size 30 with the Profile 0.06 system, calcium hydroxide paste was placed in the canals of two groups, but no medication was placed in the control group. The intracanal calcium hydroxide was removed with two different techniques, 1 week after medication: K-files one size larger than the master apical file (MAF) were used with 2.5% NaOCl and 15% EDTA solutions in one group, whilst K-files the same size as the MAF were used with 2.5% NaOCl solution in another group. Canals were obturated with gutta-percha and Tubli-Seal cement using the lateral condensation technique. The apical sealing-ability was assessed by dye leakage and cross-sections of the specimens were examined under a stereomicroscope. The dye-penetration level was measured and analyzed using Fisher's exact test and Duncan's multiple range test. Results The calcium hydroxide-medicated groups showed significantly more dye leakage than the non-medicated control group (P 0.05). The stereomicroscopic views showed a relatively uneven and thicker layer of sealer in the calcium hydroxide-medicated groups. Conclusion Calcium hydroxide intracanal medication may increase apical leakage of gutta-percha root fillings when a zinc oxide-eugenol sealer is used.

Cosmological perturbations in a generalized gravity including tachyonic condensation

Abstract: We present unified ways of handling the cosmological perturbations in a class of gravity theory covered by a general action This gravity includes our previous generalized $f(\ensuremath{\varphi},R)$ gravity and the gravity theory motivated by the tachyonic condensation We present a general prescription to derive the power spectra generated from vacuum quantum fluctuations in the slow-roll inflation era An application is made to a slow-roll inflation based on the tachyonic condensation with an exponential potential

Activation of p38 MAP kinase in the rat dorsal root ganglia and spinal cord following peripheral inflammation and nerve injury.

Abstract: The intrathecal administration of p38 MAP kinase (p38) inhibitor has been shown to reduce hyperalgesia. In the present study, we investigated the activation of p38 in the rat dorsal root ganglion (DRG) and spinal cord following peripheral tissue inflammation and nerve injury immunohistochemically. Peripheral inflammation and chronic constriction injury (CCI) of the sciatic nerve induced a significant increase in the percentage of phosphorylated (P-) p38-immunoreactive (IR) neurons, primarily small sized ones in bilateral DRGs. In contrast, following axotomy, a significant decrease in the percentage of IR neurons was observed in ipsilateral DRGs. In addition, a marked increase was observed in the number of P-p38-IR microglia in the ipsilateral laminae I-IV and IX of the spinal cord following peripheral inflammation, CCI or axotomy. These findings suggest that p38 may play an important role in hyperalgesia and the activation of the spinal microglia.

Q2 dependence of quadrupole strength in the γ*p → Δ+(1232) → pπ0 transition

Abstract: Models of baryon structure predict a small quadrupole deformation of the nucleon due to residual tensor forces between quarks or distortions from the pion cloud. Sensitivity to quark versus pion degrees of freedom occurs through the Q2 dependence of the magnetic (M1+), electric (E1+), and scalar (S1+) multipoles in the gamma*p-->Delta(+)-->p pi(0) transition. We report new experimental values for the ratios E(1+)/M(1+) and S(1+)/M(1+) over the range Q2 = 0.4-1.8 GeV2, extracted from precision p(e,e(')p)pi(0) data using a truncated multipole expansion. Results are best described by recent unitary models in which the pion cloud plays a dominant role.

Diffusion-weighted MR imaging of metastatic disease of the spine: assessment of response to therapy.

Abstract: BACKGROUND AND PURPOSE: In cases of metastatic disease of the spine, monitoring the response to medical therapy with plain radiography, bone scanning, and conventional spin-echo sequence MR imaging is unsatisfactory because of the insensitivity or nonspecific findings of these imaging modalities. The purpose of this study was to investigate signal intensity changes of bone marrow after therapy by using diffusion-weighted MR imaging to monitor the response to medical therapy in cases of metastatic disease of the spine. METHODS: Twenty-four patients with metastatic disease of the spine were examined with MR imaging. Diffusion-weighted MR imaging and spin-echo MR imaging were performed in all patients before and after radiation therapy. Follow-up diffusion-weighted MR imaging and spin-echo MR imaging were performed for comparison purposes in nine cases at 1 month, in seven cases at 2 months, in seven cases at 3 months, and in three cases at 6 months after therapy. The diffusion-weighted MR imaging sequences were based on a steady-state free precession with a low b value (165 s/mm 2 ) and a single shot stimulated echo-acquisition mode with a high b value (650 s/mm 2 ). Apparent diffusion coefficient maps were obtained using two different b values incorporated in a diffusion-weighted single shot stimulated echo-acquisition mode sequence. Apparent diffusion coefficient maps were obtained in three cases. Signal intensity changes of the metastatic disease of the vertebral bone marrow before and after therapy on conventional spin-echo sequence and diffusion-weighted MR images were evaluated. RESULTS: As shown by diffusion-weighted MR imaging, metastatic disease of the vertebral bone marrow included in our study before therapy was hyperintense to normal vertebral bodies. In 23 patients with clinical improvement, metastatic disease of the spine after therapy was hypointense relative to normal vertebral bodies on the follow-up diffusion-weighted MR images. In one patient with hepatocellular carcinoma, the clinical symptoms did not improve and follow-up bone scanning performed 6 months after therapy showed increased uptake. Persistent hyperintense bone marrow after therapy was also noted on diffusion-weighted MR images. Decreased signal intensity of the metastatic disease of the spine on diffusion-weighted MR images was observed >1 month after therapy. CONCLUSION: Diffusion-weighted MR imaging shows that, with successful therapy, there is decreased signal intensity of metastatic disease of the vertebral bone marrow.

Kinetics of selective CO oxidation in hydrogen-rich mixtures on Pt/alumina catalysts

Abstract: Selective CO oxidation on Pt/alumina catalysts in hydrogen-rich mixtures was studied in a temperature range of 150–350 °C and a concentration range of 0.5–2% for oxygen and carbon monoxide. The intrinsic kinetics of the CO oxidation was well described by a simple power-law expression with an activation energy of 78 kJ/mol and the reaction orders of −0.51 and 0.76 for the CO and the oxygen partial pressure, respectively. The selectivity showed a maximum with increasing temperature and was dependent mainly on the feed composition and the reaction temperature. But the selectivity did not show any appreciable change with respect to flow rate, indicating a constant selectivity along the catalyst bed, and Pt loading of the catalyst in the range of 0.04–1 wt.%, even though the 1 wt.% catalyst exhibited severe internal diffusional limitation. For this, the selectivity once measured for a Pt/alumina catalyst as a function of feed composition and temperature could be used for other Pt/alumina catalysts of different activities and for different conversion levels. A reactor model with an approximation of the internal effectiveness factor was developed to simulate the integral reactor performance with the 1 wt.% catalyst.

Regulation of the chondrocyte phenotype by β-catenin

Abstract: beta-Catenin regulates important biological processes, including embryonic development and tumorigenesis. We have investigated the role of beta-catenin in the regulation of the chondrocyte phenotype. Expression of beta-catenin was high in prechondrogenic mesenchymal cells, but significantly decreased in differentiated chondrocytes both in vivo and in vitro. Accumulation of beta-catenin by the inhibition of glycogen synthase kinase-3beta with LiCl inhibited chondrogenesis by stabilizing cell-cell adhesion. Conversely, the low level of beta-catenin in differentiated articular chondrocytes was increased by post-translational stabilization during phenotypic loss caused by a serial monolayer culture or exposure to retinoic acid or interleukin-1beta. Ectopic expression of beta-catenin or inhibition of beta-catenin degradation with LiCl or proteasome inhibitor caused de-differentiation of chondrocytes. Transcriptional activation of beta-catenin by its nuclear translocation was sufficient to cause phenotypic loss of differentiated chondrocytes. Expression pattern of Jun, a known target gene of beta-catenin, is essentially the same as that of beta-catenin both in vivo and in vitro suggesting that Jun and possibly activator protein 1 is involved in the beta-catenin regulation of the chondrocyte phenotype.

Improved measurement of mixing-induced CP violation in the neutral B meson system

Abstract: We present an improved measurement of the standard model CP violation parameter $\mathrm{sin}2{\ensuremath{\varphi}}_{1}$ (also known as $\mathrm{sin}2\ensuremath{\beta})$ based on a sample of $85\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $B\overline{B}$ pairs collected at the $\ensuremath{\Upsilon}(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy ${e}^{+}{e}^{\ensuremath{-}}$ collider. One neutral B meson is reconstructed in a $J/\ensuremath{\psi}{K}_{S}^{0},$ $\ensuremath{\psi}{(2S)K}_{S}^{0},$ ${\ensuremath{\chi}}_{c1}{K}_{S}^{0},$ ${\ensuremath{\eta}}_{c}{K}_{S}^{0},$ $J/\ensuremath{\psi}{K}^{*0},$ or $J/\ensuremath{\psi}{K}_{L}^{0}$ CP-eigenstate decay channel and the flavor of the accompanying B meson is identified from its decay products. From the asymmetry in the distribution of the time interval between the two B meson decay points, we obtain $\mathrm{sin}2{\ensuremath{\varphi}}_{1}=0.719\ifmmode\pm\else\textpm\fi{}0.074(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.035(\mathrm{syst}).$