[en] On September 30, 1999, a criticality accident occurred at the uranium processing facility of the JCO Co. Ltd. (hereinafter referred to as ''JCO'') Tokai plant, located in Tokaimura, Ibaraki Prefecture. This was an unprecedented accident in Japan's history of peaceful use of nuclear power, resulting in three workers exposed to severe radiation, two of whom died, and the evacuation and enforced indoor confinement of local residents. Nuclear power suppliers must take personal responsibility for ensuring safety. In this connection, the electric power industry, heavy electric machinery manufacturers, fuel fabricators, and nuclear power research organizations gathered together to establish the Nuclear Safety Network (NSnet) in December 1999, based on the resolve to share and improve the level of the safety culture across the entire nuclear power industry and to assure that such an accident never occurs again. NSnet serves as a link between nuclear power enterprises, research organizations, and other bodies, based on the principles of equality and reciprocity. A variety of activities are pursued, such as diffusing a safety culture, implementing mutual evaluation among members, and exchanging safety-related information. Aiming to share and improve the safety culture throughout the entire nuclear power industry, NSnet thoroughly implements the principle of safety first, while at the same time making efforts to restore trust in nuclear power

[en] The authors developed a three-dimensional display technique for blood vessels related to soft tissues, using MR images generated by the three-dimensional Fourier transform method or multisection method. An application of this study for neurosurgery provided satisfactory results. In this paper they describe this display technique and its clinical practice, including procedures (1) to enhance blood vessels by nonlinear filter capable of detecting three-dimensional line patterns without losing the form of soft tissues, (2) to generate three-dimensional images by the numerical projection, and (3) to present three-dimensional display utilizing the dynamic or binocular parallex (animation display or stereoscopic display). This technique facilitates the recognition of the three-dimensional structure of blood vessels related to soft tissues

[en] This work proposes a three-dimensional display method called synthesized operative view display, which is a useful tool in planning surgery. This method generates and displays a series of images that are combinations of surface and oblique images as viewed from the operative approach. MR imaging three-dimensional FT data of a case of cavernous hemangioma were acquired using three markers attached to the patient's head, and the images mentioned above were generated. The authors then used the generated images to locate the lesion and plan the craniotomy area and measured the distance between the assumed craniotomy area and the markers. These values were used to perform the actual surgery, and the craniotomy position could be precisely determined

[en] Cardiac-gated MR images of the heart were obtained utilizing gradient field refocused echo sequences with a limited (30⁰) angle and short echo time (14 msec). The images provide the anatomic and the blood flow information on the heart. Sixty images were acquired for each cardiac cycle. Three-dimensional and cross-sectional views of the heart were obtained by combining sagittal, coronal, and axial images. Dynamic displays of these three-dimensional views of the heart was performed and is expected to be helpful in understanding the anatomic and blood flow abnormalities of the heart

[en] We use real-time measurement of substrate curvature and reflection high energy electron diffraction (RHEED) methods to observe the film stress/strain behavior during epitaxial growth of Sr metal films and their oxidation process. The film stress and the thickness of the strained layer are minimized by using hydrogen-terminated Si substrates. The use of hydrogen-terminated Si(111) enables the growth of stress-free Sr layers from a thickness of 1.05 nm, whereas the films directly deposited on Si(111) 7x7 shows the presence of a strained layer with a thickness of 3.16 nm. We also observed that the intrinsic stress in the films changes drastically from compressive to tensile during the oxidation process, resulting from the variation in lattice mismatch

[en] The surface anatomy scanning (SAS) technique, which displays brain surface structures, has been developed over the past 2 years. The purpose of this study is to shorten the examination time required for surface structure imaging. The SAS technique use a very long TE sequence (e.g., SE 3000,250) with thick sections and a surface coil to enhance CSF on the brain surface. The authors' modified technique uses added multisection images, each appropriately weighted./ A selected sequence is a conventional T2-weighted multisection one (e.g., SE 3000,120), the images of which can be used for SAS and also for routine screening. Furthermore, several surface images with slightly different projection directions are obtained, and they are used for stereographic and cine display

[en] High-resolution angle-resolved photoemission spectroscopy has been carried out to clarify the anomalous superconductivity of MgB₂. We observed three bands crossing the Fermi level, which are ascribed to B2p-σ, π and surface bands. We have succeeded for the first time in directly observing the superconducting gaps of these bands separately. We have found that the superconducting-gap sizes of σ and surface bands are 6.5 ± 0.5 and 6.0 ± 0.5 meV, respectively, while that of the π band is much smaller (1.5 ± 0.5 meV). The present experimental result unambiguously demonstrates the validity of the two-band superconductivity in MgB₂

[en] The super large-sized natural circulation reactor (NCR) is conceived as a simplified approach to future nuclear power plant design with improved safety and economics. The reactor design is a low power density natural circulation type, capable of long (5 - 10 years) power production cycles. A large power output of 2000 MWe was selected for the initial scoping study. High power output and long cycle length lead to a large core diameter of ∼10 meters that requires a larger diameter reactor pressure vessel which is beyond the existing capability of steel vessel fabrication. Therefore, this unit uses prestressed concrete reactor vessel (PCRV) to allow for a very large core as well as to simplify the approach to plant safety and to provide a mild response to plant transients. The use of prestressed concrete construction removes the current size limitations imposed by a steel reactor vessel due to the steel vessel fabrication capacity. (author)

[en] SrO is a well-known buffer layer on Si for SrTiO₃ and BaTiO₃ which are highly desirable complex oxides for future generation transistor gate dielectric and ferroelectric memory applications. Furthermore, these complex oxides work as good substrates for various functional oxides including high-T_c superconductors. To fabricate integrated devices of semiconductors and such oxide materials, the epitaxial growth of SrO films on Si is very attractive. However, these properties depend strongly on the quality of thin oxide films in which large mechanical stress might be produced during their preparation. To characterize the film stress as a function of Si surface conditions, we use real-time measurement of substrate curvature during Sr film growth both on bare Si (111) 7x7 and on H-terminated Si(111). The growth of epitaxial Sr films has been achieved at room temperature by MBE. At the beginning of Sr growth on bare Si(111) 7x7, strong compressive stress is generated, indicating an immediate expansion of the surface. The compressive stress in Sr film is a result of strong interfacial strain from lattice mismatch between the film and the substrate. In case of Sr growth on H-terminated Si, however, the maximum total stress in the film is one-third of the film stress on bare Si. Stress-free Sr layers are grown from a thickness of 3 atomic layers corresponding to 1 unite cell. (Authors)

[en] We have studied the electrical resistivity ρ of the Pr-based cubic compound PrPb_3 with the Γ_3 doublet ground state. The temperature dependence of the resistivity is found to exhibit a non-Fermi liquid behavior with convex curve at high temperatures, as suggestive of the putative realization of the quadrupole Kondo effect. At low temperatures under magnetic fields, we observe anomalies associated with antiferroquadrupole (AFQ) ordering, incommensurate/commensurate transition inside the AFQ phase, and field-induced phase transition. The constructed phase diagram based on these observations well reproduces the one determined by the specific heat and magnetization measurements. Deep inside each phase, the resistivity turns to show the Fermi liquid behavior with the quadratic temperature dependence. The estimated slope of the T"2 term is almost independent of field in contrast to our previous work of PrIr_2Zn_2_0 and PrRh_2Zn_2_0 in which the slope is largely enhanced at the edge of the AFQ phase. (paper)