Genomic organization and regulation of expression of the lectin-like oxidized low-density lipoprotein receptor (LOX-1) gene

Lectin-like oxidized low-density lipoprotein receptor (LOX-1) is a recently identified receptor for oxidized low-density lipoprotein, one of the major atherogenic substances. Although LOX-1 was reported to be expressed abundantly in endothelial cells, including atheromatous lesions, the regulation of LOX-1 gene has not yet been clarified. In the present study, we isolated the rat LOX-1 gene and investigated the regulation of gene expression. The rat LOX-1 gene was encoded by a single copy gene spanning over 19 kilobases and consisted of eight exons. Exon boundaries correlated well with the functional domain boundaries of the receptor protein. The promoter region contained putative TATA and CAAT boxes and multiple cis-elements such as NF-kappaB, AP-1 and AP-2 sites, and a shear stress response element. Northern blot analysis revealed that LOX-1 gene expression was up-regulated 9-fold by shear stress, 21-fold by lipopolysaccharide, and 4-fold by tumor necrosis factor-alpha, in cultured vascular endothelial cells. LOX-1 was also expressed in macrophages but not in vascular smooth muscle cells. These data provide important information for elucidating the molecular mechanisms of LOX-1 gene regulation and suggest a role for LOX-1 in the pathophysiology of atherosclerotic cardiovascular disease.     

AIGaAsSb Buffer/Barrier on GaAs substrate for InAs channel devices with high electron mobility and practical reliability

InAs/AlGaAsSb deep quantum well was successfully formed on GaAs substrate and examined for two electron devices, Hall elements (HEs), and field-effect transistors (FETs). With a thin buffer layer of 600 nm AIGaAsSb on GaAs substrate, we observed high electron mobility more than 23000 cm²/Vs and extrinsic effective electron velocity of 2.2 x 10⁷ cm/s for a 15 nm thick InAs channel at room temperature. AIGaAsSb lattice matched to InAs was discussed from the view points of insulating property, carrier confinement, and oxidization rate. Reliability data good enough for practical use were also obtained for HEs. We demonstrated AIGaAsSb as a promising buffer/barrier layers for InAs channel devices on GaAs substrate, and we discussed the possible advantages of AIGaAsSb also for InGaAs FETs.     

A decentralized control system for stabilizing multimachine power systems

A decentralized control system is studied for stabilizing multimachine power systems. A longitudinal power system with three areas, each having one machine, is considered in this study. A decentralized control design method is proposed, which is based on the optimal regulator theory. First a centralized control system is designed without any consideration on whether state variables are all available or not. Second a pseudo-decentralized control system is designed by omitting control gains corresponding to state variables which give hardly any effects on the power system stability. It is found that only one variable of phase angle of each machine is absolutely necessary for the pseudo-decentralized control system. This leads to an idea based on power system engineering, that is to say, new variables of tieline power flow are introduced in the decentralized control system design to substitute for the phase angle of each machine. Thus a decentralized control system for power system stability can be designed using the new variables of tieline power flow. It is demonstrated from simulation studies that the decentralized control system improves even longitudinal power system stability as well as the centralized control system.     

Preparation of ultrafine zirconium dioxide particles by thermal decomposition of zirconium alkoxide vapour

Ultrafine zirconia particles are produced by thermal decomposition of zirconium tetratertiary butoxide (ZrTB) vapour. The introduction of ZrTB vapour into the cylindrical electric furnace, is achieved by three different methods: (evaporator, pressurized nebulizer and ultrasonic nebulizer). The properties of the fine particles obtained by these methods are mainly analysed by X-ray diffraction and transmission electron microscopy. It is found that ultrafine zirconia particles produced at relatively low temperatures from 600 to 700° C are spherical in the diameter range 0.035 to 0.15 μm and of tetragonal phase. Furthermore, two-component fine particles of zirconia-ilver are generated by putting the silver solid inside the furnace containing alkoxide vapour, and are deposited by inertia on to a glass substrate under low pressure to form films having a thickness of 17 to 33 μm. The electrical characteristics of the films are evaluated, and the conductance of the film is found to increase with the content of the silver component.     

Crystallographic evaluation of ZnSe crystals by x-ray diffraction

Crystallographic quality and the lattice constant of ZnSe crystals grown from Te/ Se solutions by the temperature gradient solution growth method were evaluated by using a high resolution x-ray diffractometer. The full width at half maximum of the x-ray rocking curve was 5.7 sec, a value almost equivalent to that of GaAs. The distribution of crystallographic properties along the growth direction was nearly the same excepting just on the heat-sink. The accurate lattice constant of the ZnSe crystal measured by this system was 5.6700 ± 0.000025 A.     

Fiber fuse phenomenon in triangular-profile single-mode optical fibers

The unsteady-state thermal conduction processes in triangular-profile (TP) optical fibers, which exhibited zero chromatic dispersion near 1.55 /spl mu/m, were studied theoretically with the explicit finite-difference method (FDM). It was estimated that these fibers would exhibit a high-temperature optical absorption on the basis of the high-temperature loss-increase mechanism proposed for step-index (SI) optical fibers. The core-center temperature of the TP fibers changed suddenly and reached over 7/spl times/10/sup 5/ K when a 1.064-/spl mu/m laser power of 1 W was inputted into the core layer heated at 2608 K. This rapid heating of the core initiated the "fiber fuse" phenomenon. The propagation rates of the fiber fuse, estimated at 1.064 /spl mu/m, were in fairly good agreement with the experimentally determined values. It was found that the threshold powers for initiating the fiber fuse are linearly proportional to the roots of the effective core areas of both the SI and the TP optical fibers. This coincides the experimental result reported by Seo et al.     

超声回波特征值的统计学分析方法

介绍了一种基于统计学假设检验理论进行模式识别中的特征评价与选择的方法，该方法理论意义比较清楚，计算简单，能够选出合适的特征，其实现是采用统计学中t检验方法来进行的，即用检验各组样本特征之间差异是否显著，来评价所提取的特征值的优劣；采用启发武方法和判别分析来进一步考察所提取的特征值的分类效果．实现了超声回波特征空间的降维处理与最佳特征子集选择。     

Simulation of fiber fuse phenomenon in single-mode optical fibers

The unsteady-state thermal conduction process in single-mode (SM) optical fiber was studied theoretically with the explicit finite-difference method (FDM). In the numerical calculation it was assumed that the electrical conductivity of the core layer increased rapidly above 1323 K. The core-center temperature changed suddenly and reached over 3/spl times/10/sup 5/ K when an optical power of 1 W was input into the core layer heated at 1373 K. This rapid heating of the core initiated the "fiber fuse" phenomenon. The high-temperature core areas, whose radiation spectrum extended over a wide range from the infrared to the ultraviolet regions, were enlarged and propagated toward the light source at a rate of about 0.7 m s/sup -1/. This rate was in fair agreement with the experimentally determined value.     

Depletion layer in pn-junction of diamond with phosphorus donor and boron acceptor

In order to understand characteristics of diamond pn-junction, ionized dopant and carrier profiles in pn-junction of diamond with phosphorus (P) donor and boron (B) acceptor are calculated. There exists a large transition region at a depletion layer edge due to Debye tailing at room temperature (RT). The length of Debye tailing, λ, is reduced with increasing compensation ratios and temperatures. The Debye tailing is predicted to facilitate an early effect of a pnp-bipolar transistor.