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We have investigated charging and flashover characteristics of a polymeric or glass insulator exposed to ac voltage in vacuum in order to develop compact and reliable high voltage VCBs (Vacuum Circuit Breakers). This paper focuses on charging characteristics of a cylindrical model insulator. The charging of an insulator is investigated using an electrostatic probe that measures the electric field near the triple junction on the grounded electrode. This method allows a time-resolved measurement of the charging process. The insulator was made of borosilicate, fused quartz or polymetyl methacrylate, and was in the shape of a right cylinder with 10 mm in thickness. It has been clarified that the charging is characterized by three sequential states; initiation, quasi-stable and stable states, and that the polarity of the charge is positive for these states irrespective of the voltage phase. The charging characteristics with ac voltage are compared to our previous results with dc voltage excitation. We find that the charge magnitude at the stable state coincides with that obtained by dc. The electric field on the grounded electrode, and therefore the charge magnitude, decreases with the surface roughness, and decreases as the insulation strength is increased. A computer simulation has been conducted to investigate the quasi-stable state, which clarifies that the transition in surface charge distribution being synchronous to the voltage phase is responsible for causing the quasi-stable state. Index Terms--Surface charging, charge distribution, flashover, surface roughness, solid insulator, glasses, PMMA, vacuum.

Factor XIII (FXIII) consists of the A and B subunits (FXIII-A and FXIII-B) and stabilizes fibrin clots. Defects in either the FXIII-A or FXIII-B gene lead to congenital FXIII deficiency, which manifests a life-long haemorrhagic tendency. Thus, prophylactic FXIII replacement therapy is recommended. To establish a management plan for a 30-year-old male patient with 'indefinite' FXIII deficiency (<40% of the normal FXIII), he was characterized by state-of-the-art techniques as guided by the FXIII/Fibrinogen subcommittee of ISTH/ SSC. FXIII activity turned out to be virtually undetectable by three functional assays. Four immunological assays detected essentially no FXIII protein, FXIII-A antigen, and A2B2 antigen, but normal FXIII-B antigen. Accordingly, he was diagnosed as a 'severe' FXIII-A deficiency case. He had no anti-FXIII antibodies, because a 1:1 cross-mixing test (ammonia release assay) and a five-step mixing test (amine incorporation assay) between his plasma and normal plasma demonstrated deficiency patterns. Furthermore, a dosing test using plasma-derived FXIII concentrates revealed its normal recovery. DNA sequencing analysis identified two novel mutations, W187 X & G273 V, in the F13A gene. Genetic analyses confirmed that he was a compound heterozygote and his mother and sister were heterozygotes of either one of these mutations, indicating the hereditary nature of this disorder. Molecular modelling predicted that the G273 V mutation would cause clashes with the surrounding residues in the core domain of FXIII-A, and ultimately would result in the instability of the mutant molecule. Detailed characterization of 'indefinite' FXIII deficiency made it possible to make its definite diagnosis and best management plan. [ABSTRACT FROM AUTHOR]

Abstract: The evaluation of spatially and temporally distributed records of translational shallow landslides in heterogeneous watersheds provides insights needed to understand disastrous processes. Recurrent slope instability events occurred between 1953 and 1998 in two watersheds of Mt. Aso, western Japan. This paper investigates (1) the spatio-temporal characteristics of translational shallow landslides (dimensions, numbers, densities, and area subjected to failure) observed at a particular location, (2) DEM based landform characteristics (elevation, slope angles, curvatures and their control on landslide distribution), and (3) rainfall characteristics. The evaluation of the landslide history, consequences and characteristics of spatially and temporally distributed landslides are based on the series of inventory maps for years 1954, 1977, 1990 and 1998. Geologically, the watersheds consist of pyroxene olivine andesite basalt lava, pyroclastics deposits, gravel, sand and clay deposits originated from Takadake, Nekodake, and Washigamine volcanoes. During 45 years (1953–1998), a total of 619 and 976 numbers of shallow landslides have been recognized in the Sakurakigawa and Furuegawa watersheds, respectively. Repeated sliding denuded a total surface area of 0.372 km2 in the Sakurakigawa watershed representing 35% of the watershed area. Similarly slides denuded a total of 0.534 km2 in the Furuegawa watershed representing 12% of the watershed area. For example, storm events of June 1953 and July 1990 with rainfall intensities of 49 and 61 mm h−1, respectively triggered numerous landslides. About 25% and 47% of Sakurakigawa and Furuegawa watersheds, respectively still bears the potential to produce landslides. Landslides were commonly observed where thick unconsolidated tephra layers and pyroclastics rocks overlain by thin tephra bed existed, and for a slope inclination range of 30–35°. [Copyright &y& Elsevier]

We report a case of a 41-year-old man with acute myelogenous leukemia who developed fulminant hepatitis from reactivation of trace hepatitis B virus (HBV) 2 months after complete remission. Although he became positive for HB surface antigen at the onset of fulminant hepatitis, he had been negative for HBV serum markers, and only HBV DNA was detected by polymerase chain reaction (PCR) amplification on admission. The original stocks of serum samples from all blood donors were tested again for HBV DNA by PCR, and all samples were negative. This case demonstrates that testing for HBV DNA by PCR is necessary before chemotherapy, because silent HBV carriers are rare and fulminant hepatitis may be induced by chemotherapy in patients with hematologic malignancies. [ABSTRACT FROM AUTHOR]

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