Diffusion behavior of fission product in pyrolytic silicon carbide

The concentration distributions of ¹³³Xe, ¹⁴⁰Ba, ⁸⁹Sr, ¹⁴¹Ce, ¹⁰³Ru and ⁹⁵Zr-⁹⁵Nb in a SiC layer and releases of these fission products from SiC coated fuel particles were measured in a temperature range from 1650° to 1850°C, to obtain the diffusion parameters and to investigate the diffusion behaviors in SiC. Temperature dependences of the diffusion coefficients of these fission products except ⁹⁵Zr-⁹⁵Nb were obtained. In diffusion behaviors of the alkali earth fission product, volume diffusion occured considerably besides grain boundary above 1650°C. ¹⁴¹Ce and ¹⁰³Ru diffusions were almost through grain boundaries in the temperature range. ⁹⁵Zr-⁹⁵Nb showed volume diffusion besides boundaries diffusion in their distribution annealed at 1850°C for 35 h, but those for the shorter time or at the lower temperature would be due to boundary diffusion. In comparison of the diffusion coefficients in SiC and PyC, it was proved that SiC was effective for retention of the solid fission products.     

Mortality from major causes of death and its risk factors in the elderly--26-year follow-up study in Hisayama

The authors studied mortality from major causes of death and risk factors in the elderly in a long-term prospective survey conducted in a Japanese suburban community, Hisayama. In the baseline survey in 1961, we scrutinized 1658 residents of the town aged 40 years or older accounting for 92% of the total population in this age range. Of those, 591 residents (245 men and 346 women) aged 60 years or older, who were free from major cardiovascular disease, were selected for the present study. They were followed-up for 26 years from 1961 to 1987. The average age was 67 years for men and 70 years for women, being significantly higher for women than for men. During the follow-up period, 529 subjects (89.5%) died, and 448 were autopsied (autopsy rate 84.7%). The all-cause mortality (per 1,000 person-years) after adjustment for age was 89.9 for men and 56.7 for women, the former being significantly higher than the latter (p < 0.01). The age-adjusted mortality from cerebrovascular disease was estimated to be 21.4 for men and 9.9 for women, i.e. 8.9 and 8.8 from heart disease, and 19.9 and 10.6 from neoplasm, and 18.1 and 12.2 from-pneumonia, respectively. There was significant sex difference in mortality from cerebrovascular disease, neoplasm and pneumonia (p < 0.01) but not from heart disease (p > 0.1). Multiple Cox's proportional hazards regression analysis showed systolic blood pressure and male sex to be significant risk factors for death by cerebrovascular disease. Systolic blood pressure was also a predictor for death by heart disease.(ABSTRACT TRUNCATED AT 250 WORDS)     

Simultaneous amplification of wavelength-division-multiplexed signals by a highly efficient fibre Raman amplifier pumped by high-power semiconductor lasers

We describe the first operation of a high-power semiconductor-laser pumped fibre Raman amplifier (FRA) using high-Raman-gain optical fibre in the 1.5?m region. A high optical gain of 5 dB for 60mW of pump power is obtained. We have also achieved simultaneous amplification of wavelength-division-multiplexed signals by the FRA.     

Femoral condyle geometry in the normal and varus knee

Femoral condyle geometry was evaluated in 30 normal and 30 varus knees using magnetic resonance imaging. In the sagittal view, the distal part of the medial condyle was deformed in the varus knees, but there was no significant difference in the posterior part of the medial condyle between the normal and varus knees. In the transverse view, the transepicondylar axis (a reliable rotational landmark) showed approximately 6 degrees external rotation relative to the posterior condylar axis in the varus knees and the normal knees. The results of this study suggest that no hypoplasia exists at the posterior part of the medial condyle in varus knees. In addition, the posterior condylar axis may be a reliable rotational landmark but is in relative internal rotation in varus knees when total knee arthroplasty is performed.