A recursive construction algorithm for covariance control

This paper proposes an algorithm to compute solutions X to the linear matrix equation and inequality of the type (I-BB⁺)(AX+XA'+W)(I-BB⁺)=0, X>0. This problem arises in the synthesis of covariance controllers; the set of symmetric matrices X assignable as a closed-loop state covariance by a stabilizing controller is characterized by these conditions. Our algorithm generates analytical solutions to the above problem in a recursive manner. In this sense, our algorithm is essentially different from other computational methods pertinent to this problem, such as convex programming. As a result, the algorithm does not involve the issue of convergence and terminates in an a priori known finite number of steps. Thus, the computational complexity is expected to be much less than that of other methods     

Interpretation of Hydrated States of Sodium Silicate Glasses by Infrared and Raman Analysis

Infrared spectra of thin films (a few micrometers) of hydrated sodium silicate glasses after heating at temperatures from 100° to 400°C were measured in the spectral region from 400 to 4300 cm⁻¹. Also, Raman spectra of hydrated glasses were measured in the region from 100 to 1400 cm⁻¹. Water molecules in hydrated glasses were classified into three types by the bonding configuration: water molecules interacting with Si–OH groups, nonbridging oxygens, and bridging oxygens. On the basis of the fundamental bands observed here, we calculated the wave numbers of the combination-overtone bands of water molecules and SiOH groups in hydrated glasses. The calculated wave numbers satisfactorily agreed with observed wave numbers in the nearinfrared region.     

Scanning-laser-beam semiconductor pH-imaging sensor

We have constructed a two-dimensional (2-D) pH-imaging sensor that enables us to observe th H⁺ distribution produced by living cells. The pH-sensing principle is similar to that of thelight-addressable potentiometric sensor. The electrolyte-insulator-semiconductor (EIS) structure (electrolyte---Si₃N₄---SiO₂---Si) is illuminated by a focused (1 μm) and modulated (1–10 kHz) He—Ne laser bean from the backside of the semiconductor, and the a.c. photocurrent flowing through the EIS structure is measured. By scanning the laser beam, 2-D pH images can be obtained. By using this sensor, pH distributions of colonies of yeast (Saccharomyces cerevisiae) have been observed. The spatial resolution of this sensor could be improved by thinning the Si wafer.     

A Modeling and Rendering Method for Snow by Using Metaballs

The display of natural scenes such as mountains, trees, the earth as viewed from space, the sea, and waves have been attempted. Here a method to realistically display snow is proposed. In order to achieve this, two important elements have to be considered, namely the shape and shading model of snow, based on the physical phenomenon. In this paper, a method for displaying snow fallen onto objects, including curved surfaces and snow scattered by objects, such as skis, is proposed. Snow should be treated as particles with a density distribution since it consists of water particles, ice particles, and air molecules. In order to express the material property of snow, the phase functions of the particles must be taken into account, and it is well-known that the color of snow is white because of the multiple scattering of light. This paper describes a calculation method for light scattering due to snow particles taking into account both multiple scattering and sky light, and the modeling of snow.     

Spindle cell carcinoma of the breast: a case report and an immunohistochemical study including p53 and Ki-67 expression

A rare case of spindle cell carcinoma (SpCC) of the breast occurring in a 51-year-old Japanese woman is reported. A firm and well-circumscribed tumor, measuring 9 x 8.5 x 8.5 cm, was located on the upper lateral region of the right breast. Microscopically, the tumor consisted of sheets of both malignant spindle cells and poorly differentiated ductal carcinoma containing squamoid islands with gradual transition to the spindle cell component. The immunocytochemical expression of epithelial markers was recognized in the spindle cells, as well as in the carcinomatous cells. Moreover, the spindle cell component expressed vimentin, alpha-smooth muscle actin and S-100 protein. Ultrastructurally, in addition to the features of adenocarcinoma, squamous or myoepithelial differentiation was confirmed in the spindle cell component. These findings thus suggest an epithelial origin with squamous differentiation and myoepithelial participation in the genesis of SpCC. In a comparative study, the expression of p53 protein and Ki-67 as a proliferation marker in each component of this tumor was also investigated. The mean p53 labeling index (LI) in both the carcinomatous and spindle cell area was similar, however the mean MIB-1 LI in the spindle cell area was significantly higher than that in the carcinomatous area. The results indicate that p53 overexpression is involved in the tumorigenesis of both components in the SpCC, and the spindle cell component shows a higher degree of proliferative activity than the carcinomatous component.     

The long-term results of percutaneous isolated hepatic perfusion for patients with advanced hepatocellular carcinoma

We studied the long-term outcome of percutaneous isolated hepatic perfusion (PIHP) for patients with hepatocellular carcinoma. This study included 31 patients with Stage IVA and 5 with IVB disease treated by PIHP until December, 1997. The mean age and tumor diameter were 55 and 7.7 cm, respectively. Twenty-two had portal vein invasion, 13 had hepatic vein invasion, and all patients had multiple intrahepatic metastases of more than 5 tumor foci. The PIHP with adriamycin or cisplatin was undertaken in a total of 50 treatments in these 36 patients. CR was observed in 6 and PR in 13 with an overall response rate of 59%, excluding 4 patients who were not evaluable. Five of 6 patients with CR remain free of disease at 7 to 54 months after the first treatment. The overall survival rate was 67% at 1 year and 32% at 5 years. The survival rates of Stage IVA patients (1-year = 71%, 5-year = 36%) were higher than Stage IVB patients (1-year = 20%, 5-year = 0%). The 5-year survival rates of patients with vascular invasion (Vp1-3 = 23%, Vv1-3 = 8%) were lower than those without it (Vp0 = 47%, Vv0 = 51%). These results indicated that PIHP achieved a 5-year survival rate of approximately 40% in patients with multiple advanced hepatocellular carcinoma in the absence of distant organ metastases and marked vascular invasion, and yielded complete long-term remission in some of these patients.     

Molecular cloning, expression, and enzymatic characterization of rabbit hydroxysteroid sulfotransferase AST-RB2

Cytosolic sulfotransferases, which consist of at least three gene families, play a major role in activation and detoxification of both endogenous and exogenous chemicals. We recently purified a rabbit sulfotransferase, AST-RB2, showing high activities to both hydroxysteroids and amines. To characterize this enzyme, a rabbit cDNA library was screened using anti-AST-RB2 antibodies. The isolated cDNA was judged to encode AST-RB2 (ST2A8) based on the amino acid sequences of peptide fragments obtained from purified AST-RB2. The cDNA showed high similarity to other mammalian hydroxysteroid sulfotransferases (ST2) at the amino acid level (58-68%), but low similarity to aryl sulfotransferases (ST1) (less than 37%). The protein expressed in Escherichia coli catalyzed sulfation of typical ST2 substrates. Therefore, ST2A8 was judged to belong to the ST2 family from both its primary structure and substrate specificity. The ST2A8 protein expressed in E. coli clearly differed from rat ST2A1 and ST2A2 on its localization (cytosol/insoluble fraction ratio). ST2A8 had no activity to lithocholate, but showed the highest catalysis on dehydroepiandrosterone and testosterone among the four forms (ST2A1, ST2A2, ST2A3, and ST2A8), indicating a clear difference between ST2A forms in substrate specificity to endogenous chemicals.