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We report measurement of initial G2-chromatid breaks in normal human fibroblasts exposed to various types of high-LET particles. Exponentially growing AG 1522 cells were exposed to gamma rays or heavy ions. Chromosomes were prematurely condensed by calyculin A. Chromatid-type breaks and isochromatid-type breaks were scored separately. The dose response curves for the induction of total chromatid breaks (chromatid-type + isochromatid-type) and chromatid-type breaks were linear for each type of radiation. However, dose response curves for the induction of isochromatid-type breaks were linear for high-LET radiations and linear-quadratic for gamma rays. Relative biological effectiveness (RBE), calculated from total breaks, showed a LET dependent tendency with a peak at 55 keV/micrometer silicon (2.7) or 80 keV/micrometer carbon (2.7) and then decreased with LET (1.5 at 440 keV/micrometer). RBE for chromatid-type break peaked at 55 keV/micrometer (2.4) then decreased rapidly with LET. The RBE of 440 keV/micrometer iron particles was 0.7. The RBE calculated from induction of isochromatid-type breaks was much higher for high-LET radiations. It is concluded that the increased production of isochromatid-type breaks, induced by the densely ionizing track structure, is a signature of high-LET radiation exposure.

We report measurement of initial G2-chromatid breaks in normal human fibroblasts exposed to various types of high-LET particles. Exponentially growing AG 1522 cells were exposed to gamma rays or heavy ions. Chromosomes were prematurely condensed by calyculin A. Chromatid-type breaks and isochromatid-type breaks were scored separately. The dose response curves for the induction of total chromatid breaks (chromatid-type + isochromatid-type) and chromatid-type breaks were linear for each type of radiation. However, dose response curves for the induction of isochromatid-type breaks were linear for high-LET radiations and linear-quadratic for gamma rays. Relative biological effectiveness (RBE), calculated from total breaks, showed a LET dependent tendency with a peak at 55 keV/micrometer silicon (2.7) or 80 keV/micrometer carbon (2.7) and then decreased with LET (1.5 at 440 keV/micrometer). RBE for chromatid-type break peaked at 55 keV/micrometer (2.4) then decreased rapidly with LET. The RBE of 440 keV/micrometer iron particles was 0.7. The RBE calculated from induction of isochromatid-type breaks was much higher for high-LET radiations. It is concluded that the increased production of isochromatid-type breaks, induced by the densely ionizing track structure, is a signature of high-LET radiation exposure.

It is widely known that emissions of greenhouse gases from anthropogenic activities have been dramatically increasing at the unprecedented rate over the past several decades, and causing the global climate change. To assess the future trends of such global climate change, it is necessary to project future greenhouse gas emissions. In this paper, we explore the effects of further economic growth on CO2 emissions with the use of a multi-sector, multi-region global CGE model, and with explicit consideration to the endogeneity of emission regulations, i.e. the dependence of regulations on the level of income. The relationship between income level and emission regulations are derived from the consequence of the Kyoto Protocol type emission regulations. Our main finding is summarized as follows. Carbon taxes rise in all regions with economic growth because all regions, especially LDC regions, enjoy the rise in per capita income. However, the responsiveness of carbon taxes to income change is too weak to restrain the increase in emissions. In other words, given the degree of the responsiveness of regulations inferred from the acceptance of the Kyoto Protocol type regulations, carbon emissions are likely to increase all over the world along with further economic growth.

It is widely known that emissions of greenhouse gases from anthropogenic activities have been dramatically increasing at the unprecedented rate over the past several decades, and causing the global climate change. To assess the future trends of such global climate change, it is necessary to project future greenhouse gas emissions. In this paper, we explore the effects of further economic growth on CO2 emissions with the use of a multi-sector, multi-region global CGE model, and with explicit consideration to the endogeneity of emission regulations, i.e. the dependence of regulations on the level of income. The relationship between income level and emission regulations are derived from the consequence of the Kyoto Protocol type emission regulations. Our main finding is summarized as follows. Carbon taxes rise in all regions with economic growth because all regions, especially LDC regions, enjoy the rise in per capita income. However, the responsiveness of carbon taxes to income change is too weak to restrain the increase in emissions. In other words, given the degree of the responsiveness of regulations inferred from the acceptance of the Kyoto Protocol type regulations, carbon emissions are likely to increase all over the world along with further economic growth.

Confined jets of two-phase mist flow are important in the development of a two-phase ejector for the refrigeration cycle. However, the flow characteristics of the two-phase ejector have not been elucidated to date due to the nonequilibrium of velocity and temperature. In this study, the mixing characteristics of two-phase mist flow in the two-phase ejector were investigated experimentally. The pressure increases in the mixing section and the diffuser of the ejector were measured. The following results were obtained by comparison of the measured pressure increase with that calculated using a simple theory. Increasing the length and decreasing the diameter of the mixing section were effective for raising the pressure. The energy efficiency of the two-phase ejector used in this experiment was approximately 10%. This efficiency should be increased by improving the mixing characteristics of the ejector and the nozzle efficiency. ・rights：日本機械学会・rights：本文データは学協会の許諾に基づきCiNiiから複製したものである・relation：isVersionOf：http://ci.nii.ac.jp/naid/110002981385/

Confined jets of two-phase mist flow are important in the development of a two-phase ejector for the refrigeration cycle. However, the flow characteristics of the two-phase ejector have not been elucidated to date due to the nonequilibrium of velocity and temperature. In this study, the mixing characteristics of two-phase mist flow in the two-phase ejector were investigated experimentally. The pressure increases in the mixing section and the diffuser of the ejector were measured. The following results were obtained by comparison of the measured pressure increase with that calculated using a simple theory. Increasing the length and decreasing the diameter of the mixing section were effective for raising the pressure. The energy efficiency of the two-phase ejector used in this experiment was approximately 10%. This efficiency should be increased by improving the mixing characteristics of the ejector and the nozzle efficiency. ・rights：日本機械学会・rights：本文データは学協会の許諾に基づきCiNiiから複製したものである・relation：isVersionOf：http://ci.nii.ac.jp/naid/110002981385/

For global survival, we need to launch a rapid regeneration of the nuclear power industry. The replacement of the present fossil fuel industry requires a doubling time for alternative energy sources of 5–7 years and only nuclear energy has the capability to achieve this. The liquid metal cooled fast breeder reactors (LMFBR) have the best breeding criteria but the doubling time exceeds 20 years. Further, the use of plutonium in these systems has the potential of nuclear proliferation. The Thorium Molten-Salt Nuclear Energy Synergetic System [THORIMS-NES], described here is a symbiotic system, based on the thorium–uranium-233 cycle. The production of trans-uranium elements is essentially absent in Th–U system, which simplifies the issue of nuclear waste management. The use of 233 U contaminated with 232 U as fissile material, instead of plutonium/ 235 U makes this system nuclear proliferation resistant. The energy is produced in molten-salt reactors (FUJI) and fissile 233 U is produced by spallation in Accelerator Molten-Salt Breeders (AMSB). This system uses the multi-functional ‘‘single-phase molten-fluoride” circulation system for all operations. There are no difficulties relating to ‘‘radiation-damage”, ‘‘heat-removal” and ‘‘chemical processing” owing to the simple ‘‘idealistic ionic liquid” character of the fuel. FUJI is size-flexible, and can use all kinds of fissile material achieving a nearly fuel self-sustaining condition without continuous chemical processing of fuel salt and without core-graphite replacement for the life of the reactor. The AMSB is based on a single-fluid molten-salt target/blanket concept. Several AMSBs can be accommodated in regional centers for the production of fissile 233 U, with batch chemical processing including radio-waste management. FUJI reactor and the AMSB can also be used for the transmutation of long-lived radioactive elements in the wastes and has a high potential for producing hydrogen-fuel in molten-salt reactors. The development and launching of THORIMS-NES requires the following three programs during the next three decades:

For global survival, we need to launch a rapid regeneration of the nuclear power industry. The replacement of the present fossil fuel industry requires a doubling time for alternative energy sources of 5–7 years and only nuclear energy has the capability to achieve this. The liquid metal cooled fast breeder reactors (LMFBR) have the best breeding criteria but the doubling time exceeds 20 years. Further, the use of plutonium in these systems has the potential of nuclear proliferation. The Thorium Molten-Salt Nuclear Energy Synergetic System [THORIMS-NES], described here is a symbiotic system, based on the thorium–uranium-233 cycle. The production of trans-uranium elements is essentially absent in Th–U system, which simplifies the issue of nuclear waste management. The use of 233 U contaminated with 232 U as fissile material, instead of plutonium/ 235 U makes this system nuclear proliferation resistant. The energy is produced in molten-salt reactors (FUJI) and fissile 233 U is produced by spallation in Accelerator Molten-Salt Breeders (AMSB). This system uses the multi-functional ‘‘single-phase molten-fluoride” circulation system for all operations. There are no difficulties relating to ‘‘radiation-damage”, ‘‘heat-removal” and ‘‘chemical processing” owing to the simple ‘‘idealistic ionic liquid” character of the fuel. FUJI is size-flexible, and can use all kinds of fissile material achieving a nearly fuel self-sustaining condition without continuous chemical processing of fuel salt and without core-graphite replacement for the life of the reactor. The AMSB is based on a single-fluid molten-salt target/blanket concept. Several AMSBs can be accommodated in regional centers for the production of fissile 233 U, with batch chemical processing including radio-waste management. FUJI reactor and the AMSB can also be used for the transmutation of long-lived radioactive elements in the wastes and has a high potential for producing hydrogen-fuel in molten-salt reactors. The development and launching of THORIMS-NES requires the following three programs during the next three decades: