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941.
Martini R. Bethea C. Capasso F. Gmachl C. Paiella R. Whittaker E.A. Hwang H.Y. Sivco D.L. Baillargeon J.N. Cho A.Y. 《Electronics letters》2002,38(4):181-183
Experimental results for an optical free-space high-speed link using direct modulated mid-infrared (λ = 8.1 μm) quantum cascade lasers are presented. A total of 800 digitally encoded multimedia channels were transmitted. The reliability of the system against weather influence (fog) was experimentally compared to that of a near-infrared (λ = 0.85 μm) link 相似文献
942.
KC Park KH Kim SW Youn JH Hwang KH Park JS Ahn YG Kim SD Kim DY Lee JH Choe JH Chung KH Cho 《Canadian Metallurgical Quarterly》1998,139(6):1087-1091
Bowenoid papulosis (BP) of the genitalia, characterized by the histological findings of a squamous cell carcinoma, follows a largely benign clinical course. The detection of oncogenic human papilloma viruses (HPV) from BP points to an aetiological role of these viral infections. A 47-year-old man with multiple genital skin lesions was seen over a 10-year period with the diagnosis of BP. Recently, he attended again with a recurrent genital tumour that was diagnosed as squamous cell carcinoma. His genital lesions progressed and became polymorphic in appearance, from a wart-like tumour to a reddish invasive plaque. To screen for the presence of different HPV sequences from different skin lesions and to correlate each HPV type with distinct clinical manifestations, polymerase chain reaction and single-strand conformational polymorphism (PCR-SSCP) were performed. PCR-SSCP revealed the presence of several types of HPV from different genital lesions. Sequencing results disclosed that he had a mixed infection of HPV6b, HPV16, HPV18 and HPV33, respectively. Interestingly, the clinical findings were fairly well correlated with the oncogenic potential of HPV found from each lesion. 相似文献
943.
The behaviors of concentric-double inclusions dispersed in continuous media are investigated theoretically to find some possibilities
of improving toughness of composite materials by dispersing double-inc’usions instead of single-inclusions. The general solutions
of the Stokes equation, expressed in terms of the spherical harmonics, are used for analyzing the problems that are related
to the concentric-double inclusions. From the analysis, it is found that the pressure and stress fields inside and outside
the inclusion can be modified by changing the modulus ratios and the thickness of shell layer. Especially, the positions of
the minimum pressure points and the maximum stress points turn out to be controllable with some degree of freedom. 相似文献
944.
945.
SH Cho JY Seo DC Choi HJ Yoon YJ Cho KU Min GK Lee JW Seo YY Kim 《Canadian Metallurgical Quarterly》1996,26(10):1210-1219
BACKGROUND: There have been many studies concerning pathological changes in bronchial mucosa from asthmatics; however, few studies has been carried out to evaluate pathological changes according to the severity of asthma. OBJECTIVE: This study was designed to evaluate the cellular components in bronchoalveolar lavage fluid (BALF) and histological abnormalities in asthmatics according to the severity of asthma. METHODS: Bronchoalveolar lavages, bronchoscopic biopsies and ultrastructural examinations were performed in 13 asthmatics and 11 (BAL) or four (biopsies) non-asthmatic controls. The proportions of epithelial cells and correlations with PC20Meth which reflects bronchial hyperresponsiveness. Light microscopic examination revealed loss of epithelium, inflammatory cell infiltrations and thickening of the basement membrane which also showed significant correlation with PC20Meth. Hypertrophy of airway smooth muscles and hyperplasia of mucous glands were prominent in asthmatics but there was no difference according to the severity of asthma. Ultrastructural examination revealed that basement membrane thickening on light microscopic examination is due to the increased subepithelial collagen deposition with normal thickness of basal lamina. CONCLUSION: These data suggest that loss of epithelial cells, infiltration of inflammatory cells, especially eosinophils, and increased deposition of subepithelial collagen play major roles in determining the severity of asthma and non-specific bronchial hyperresponsiveness. 相似文献
946.
Ketones react with primary amines in dioxane at 180 °C in the presence of a catalytic amount of a ruthenium catalyst to give the corresponding α-alkylated ketones in moderate to good yields. With alkyl(methyl) ketones, the alkylation takes place exclusively at less-hindered methyl position over α-methylene. 相似文献
947.
Young-Gyu Kim Seok-Beom Cho Pil-Jong Kim Boo-Kil Kwon 《Journal of Mechanical Science and Technology》2006,20(3):329-334
This paper presents the evaluation of LPG (Liquefied petroleum gas) regulators for home use. For the evaluation, several properties
of the regulators were experimentally analyzed, such as the operation of safety device, the adjusting and lock-up pressure,
the adjusting spring and the diaphragm, with respect to the used time of the regulators. Experimental results showed that
the initial operation performances of regulators were degraded with increase of the service time and also showed that the
degradation of the performance and material property could become serious after about six-year-use of the regulators. 相似文献
948.
Cho K.J. Kim W.J. Stapleton S.P. Kim J.H. Lee B. Choi J.J. Kim J.Y. 《Electronics letters》2006,42(12):704-705
A 40 W gallium-nitride microwave Doherty power amplifier for WCDMA repeater applications is presented. The main amplifier and peaking amplifier are implemented using two 20 W PEP GaN HEMTs. Performance is evaluated for broadband gain, power efficiency and adjacent-channel-power-ratio (ACPR). Experimental results of the GaN Doherty amplifier yielded a power gain of over 11 dB from 1.8 to 2.5 GHz, 68% power added efficiency at 40 W peak power. Good linearity performance of -48 dBc ACPR is obtained at a peak-to-average ratio of 9.8 dB. 相似文献
949.
J. R. Cho K. W. Kim J. K. Lee T. H. Park W. Y. Lee 《International journal for numerical methods in engineering》2002,55(6):733-752
In this paper, we address analytical and numerical studies on the free vibration of fluid–structure interaction problems considering the fluid compressibility. According to the separation of variables together with the boundary condition enforcement, we first derive a compressible‐fluid velocity potential function. Next, we split the structure region into the wet and dry parts, for which we apply the Novozhilov thin shell theory. Combining two dynamic displacement fields, for two split structure parts, using the displacement compatibility conditions, we finally obtain a simultaneous equation system for computing natural frequencies and modes. According to the derived analytical formulae, we compute natural frequencies and modes, stress resultants, together with the comparison with the FEM analysis and the incompressible case. Numerical results show, compared to the incompressible case, that the compressible case produces lower natural frequencies and, furthermore, the relative difference is influenced by the slenderness of tanks and the relative liquid fill height. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
950.