Evidence for an antemortem injury of a burned head dissected from a burned body

This paper describes risk factors for dental caries identified among 491 2-year-olds in the city of Ume?, Sweden. The study was performed as a risk screening for dental caries according to a method developed for use by dental assistants. The sugar consumption was high, 80% of the 2-year-olds had sweets once a week or more and 25% had sweet beverages once a day or more frequently. In addition, 14% of the children had a meal at night and most common were formula, bovine milk or breastmilk. The majority of the parents brushed the child's teeth at least daily using fluoride toothpaste. Among the children 6% had a chronic somatic disorder and 6% had an intolerance towards specific foods, milk being the most common. The high level of sugar consumption indicates that improved dental health education focusing on the importance of limiting sugar consumption is needed among parents with young children.     

Breakdown of YBCO thin films during current limiting and methods of improving current limiting performance

We performed fault current limiting tests using YBCO thin films and investigated the reasons for their breakdown during current limiting. There were two patterns of film breakdown. One occurred immediately after current limiting and the other occurred during current limiting. In film breakdown, the quench propagation speed showed almost no change with increasing energy consumption per unit time, but the energy consumption per unit area increased with increasing energy consumption per unit time. Therefore, local areas of the film reached the melting point and arcing occurred. It is therefore concluded that the performance of the films can be improved by decreasing the energy consumption per unit time. Connecting a parallel capacitor to the film in order to limit the energy consumption per unit time is proposed and tested as a measure to improve the current limiting performance of thin films. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(1): 20–27, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20709     

Magnetization switching by spin-polarized current in low-resistance magnetic tunnel junction with MgO [001] barrier

Current-induced magnetization switching (CIMS) was demonstrated in low resistance magnetic tunnel junctions (MTJs) with thin MgO [001] barrier. The resistance change by CIMS was more than 100%, which is much larger than the previous report in Al-O based MTJs. The switching current density was about 2/spl times/10/sup 7/ A/cm/sup 2/, which was comparable with that reported values in metallic multilayers.     

Measurement of the property of cooled lead molybdate as a scintillator

Lead molybdate (PbMoO₄) is found to be an efficient scintillator when cooled down to liquid nitrogen temperature. The scintillation light of PbMoO₄ excited by γ-rays amounts to as much as 16% of that of NaI(Tl) in the wavelength range between 180 nm and 650 nm and the decay time is as long as 11 μs if it is cooled below 100 K. Since ¹⁰⁰Mo, whose natural abundance is 9.6%, is a double β decay nuclide, the PbMoO₄ can be useful for the double β decay experiment.     

Development of a large volume zero boil-off liquid xenon storage system for muon rare decay experiment (MEG)

We have developed a new type of photon detector for an experiment aimed at searching for the lepton flavor violating decay μ⁺ → e⁺γ. In this experiment, a total of 900 L of liquid xenon is used in order for the scintillation detector to detect γ-rays with an extremely high sensitivity, where the liquid xenon is viewed by an array of 846 photomultipliers from all sides. The entire amount of xenon should be stored in certain storage systems before the start of the experiment, during detector maintenance in the period of accelerator shutdown, etc. We have developed a new liquid xenon storage system by employing the zero boil-off condition by using a pulse tube cryocooler. The details of system and its performance results are described in this article.     

SRAM cell stability under the influence of parasitic resistancesand data holding voltage as a stability prober

The reliability and performance of SRAM are highly dependent on the cell stability, and the stability is affected by parasitic resistances in a memory array. The parasitic resistances result in a correlative behavior of the cells and are difficult to analyze and measure in a memory array. This topic has been rarely discussed in the literature. In this paper, the correlative behavior is analyzed by trajectories in a phase diagram composed by cell storage nodes. Electrical probing is done by the data holding test. The validity of the analysis and the probing method is confirmed by the measurements on a 0.8-μm 1-Mb CMOS SRAM. An aspect of the cell scaling with attention to the parasitic resistance is also discussed     

Liquid xenon scintillation calorimetry and Xe optical properties

The optical properties of liquid xenon (LXe) in the vacuum ultra violet (VUV), determining the performance of a scintillation calorimeter, are discussed in detail. The available data, measured in a wider spectral region from visible to UV light, and in a large range of Xe densities, from gas to liquid, are examined. It is shown that this information can be used for deriving the LXe optical properties in the VUV. A comparison is made with the few direct measurements in LXe for VUV light resulting from the LXe excitation by ionizing particles. A useful relation is obtained which connects the Rayleigh scattering length to the refractive index in LXe.     

Direct dark matter search program with bolometers at the University of Tokyo

Bolometers are being developed at the University of Tokyo aiming at a search for galactic dark matter. We have succeeded in constructing a small-sized bolometer with 2.8 gram of lithium fluoride crystal with an rms energy resolution of 3.8 ke V for 60-ke V rays. Both lithium and fluorine are expected to be suitable for the detection of possible particle dark matter with a spin-dependent interaction like supersymmetric neutralinos. Fabrication of Neutron Transmutation Doped (NTD) germanium is also in progress to make a number of thermistors with uniform sensitivities to be used for multi-module bolometers. When the development of a full-sized detector with a total mass of order one kilogram is completed, we plan to install it in the Kamioka underground laboratory.     

A 4-Mb CMOS SRAM with a PMOS thin-film-transistor load cell

A 4-Mb (512 K words by 8-b) CMOS static RAM (SRAM) with a PMOS thin-film transistor (TFT) has been developed. The RAM can obtain a much larger data-retention margin than a conventional high-resistive load-type well by using the PMOS TFT as a memory cell load. An internal voltage down-converter architecture with an external supply voltage-level sensor not only realizes a highly reliable 0.5-μm MOS transistor operation but also a sufficiently low standby-power dissipation characteristic for data battery-backup application. A self-aligned equalized level sensing scheme can minimize the sensing delay for a local sense amplifier to drive a large load capacitance of a global sensing bus line. The RAM is fabricated using a 0.5 μm, triple-poly, and double-aluminum with dual gate-oxide-thickness CMOS process technology. The RAM operates under a single 5-V supply voltage with 23-ns typical address access time and 20- and 70-mA operation current at 10 and 40 MHz, respectively