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931.
G. F. R. Ellis 《General Relativity and Gravitation》1992,24(10):1047-1068
This paper gives a covariant formalism enabling investigation of the possibility of change of signature in classical General Relativity, when the geometry is that of a Robertson-Walker universe. It is shown that such changes are compatible with the Einstein field equations, both in the case of a barotropic fluid and of a scalar field. A criterion is given for when such a change of signature should take place in the scalar field case. Some examples show the kind of resulting exact solutions of the field equations. 相似文献
932.
B. F. Araujo H. T. Matsuda T. A. Kuada J. A. Araujo 《Journal of Radioanalytical and Nuclear Chemistry》1992,166(1):75-83
In the actinide separation process using TBP as extractant, hydrolytic and radiolytic reactions cause a gradual decomposition of the extractant, resulting in the formation of degradation products which can affect process performance adversely. The TBP diluent has to be cleaned from these degradation products before it is reused. This paper deals with a procedure for solvent cleanup, using a fourstage continuous contactor for increasing the scrubbing efficiency. 相似文献
933.
M F Yama 《The Journal of the Acoustical Society of America》1992,91(1):327-335
In the present study detection under diotic (NoSo) and dichotic (NoS pi) listening conditions in a forward masking paradigm was investigated. Both the level of a noise masker and the temporal separation between the masker and a 250-Hz tone burst served as independent variables. Results showed that most of the variance in the data could be accounted for by the amount of masking in the NoSo condition, independent of the value of the temporal parameter, which itself accounted for only 1.4% of the variance that remained. Once the data were corrected for NoSo masking effectiveness, the MLD was found to decrease by only 1.4 dB as temporal separation increased from 5-100 ms, which is consistent with a very long time constant for the binaural system. Consistent with this finding, it was shown that slope changes of the growth of masking functions, for simultaneous as compared to forward masking, were similar for both the NoSo and NoS pi conditions. 相似文献
934.
Day-side auroral signatures based on simultaneous, coordinatedobservations at Svalbard and Greenland
Egeland A. Carlson H.C. Denig W.F. Fukui K. Weber E. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1992,20(6):726-739
The height distribution of the dayside cusp aurora and the relation between optical emissions and net downward electron energy flux are discussed. These two important characteristics of day-side cusp aurora are still unknown. It is instructive to compare particle flux and optical luminosity because these two quantities should be proportional if the cusp aurora is caused by electron impact, as has been found for nighttime aurora in the oval. Furthermore, there should then be a direct relation between auroral altitudes and particle energy. Based on coordinated auroral observations at Svalbard and Greenland, together with simultaneous, overhead F-9 satellite measurements, these quantities have been evaluated 相似文献
935.
Summary A Modified-Melt-Powder-Melt-Growth (MMPMG) technique has been developed for the preparation of melt-textured Y-Ba−Cu−O pellets.
To test their performances, the samples were characterized with respect to their microstructure, pinning strength and interaction
force with permanent magnets. A superconducting magnetic bearing was built and integrated in a levitating flywheel system
for energy storage.
Paper presented at the “VII Congresso SATT?, Torino, 4–7 October 1994.
Under a Fondazione Confalonieri grant. 相似文献
936.
937.
Gas-phase cigarette smoke (GPCS) was able to induce lipid peroxidation in lecithin liposomes, rat liver microsomes, and rat lung cells (RLC), and change the membrane fluidity of RLCs. Lipid free radicals were trapped in a GPCS-treated microsomal suspension by using 4-POBN as the spin trap. In addition, it was found that GPCS-peroxidized liposomes in appropriate degree of lipid peroxidation had the ability to increase the generation of superoxide anions in rat peritoneal neutrophils (RPN). Effects of green tea polyphenols (GTP) on the GPCS-induced damages were investigated The results showed that GTP was capable of inhibiting the GPCS-induced damages. 相似文献
938.
The breakup of suspended, agglomerated submicron particles was studied by exposing the aerosol to weak shock waves of varying strength under conditions 400 ms?1?v?880 ms?1. A newly developed laser light-scattering diagnostic employing a top hat laser profile was used to size the particles passing through a very small scattering volume. By Comparing the optically measured particle size in front of and behind shock waves, the breakup of agglomerated particles could be clearly identified. The experiments indicate that the aerodynamic forces behind an incident shock overcome the particle binding force resulting in disintegration of the submicron agglomerates. The results are presented in form of a modified Weber number. 相似文献
939.
E. M. Glebov V. P. Grivin V. F. Plyusnin A. V. Udaltsov 《Journal of Structural Chemistry》2006,47(3):476-483
Interaction between MnCl2 and diethylamine (DEA) in aqueous solutions has been studied by UV, IR, and EPR spectroscopy as part of the design and research program on models of natural photosystems. The composition of the precipitate for comparable concentrations of reagents and solute oxygen has been investigated. Mn(II) was found to be oxidized with oxygen to give MnO2·H2O as a precipitate. In the solution over the precipitate, Mn(III) complexes with DEA are formed; the complex molecule has four and six amine molecules in the coordination sphere. 相似文献
940.