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71.
1. Some groups with the small index property In this paper we shall use the methods of the paper [6] by Hodges,Hodkinson, Lascar and Shelah to show that the free group ofcountably infinite rank and certain relatively free groups ofcountably infinite rank have the small index property. 相似文献
72.
73.
We show that a theorem of Shchepin and Repovš concerning the smoothness of compacta follows from the theory of semicontinuous relations. 相似文献
74.
G. J. Homer P. F. Smith J. D. Lewin S. J. Robertson J. U. D. Langridge D. Evans C. J. Brown M. Gonsalves A. K. Gyani 《Zeitschrift fur Physik C Particles and Fields》1992,55(4):549-554
The magnetic levitation technique has been used to test for fractional electric charge in sea water, using steel balls coated with sea water residue by evaporation. The objective was to reach concentration levels below 1 g?1 which might result from cosmic ray interactions. Four stages of increasing sensitivity are reported: (1) residue from direct evaporation of unprocessed sea water, (2) residue from sea water samples enriched by ion exchangen, (3) residue reduced by high temperature evaporation, and (4) hypothetical enrichment by dilution and separation of soluble residue. Stages 1–3 are based on the generally accepted preferential retention of fractional charge during evaporation, but stage 4 limits are subject to uncertainties in the enrichment process. No evidence for fractional charge was found in a total of about 130 samples tested in these four stages. Samples containing positive and negative ions were tested separately, and concentration limits are reported for each of the stages. Levels in the region 0.01–0.1g?1 were reached in stage 3, and 0.001 g?1 in stage 4. 相似文献
75.
76.
Vernon R. Morris Fida Mohammad Lynnette Valdry William M. Jackson 《Chemical physics letters》1994,220(6):448-454
Time-resolved IR emission spectroscopy (TRIES) has been used to study infrared emission in the 3400–3100 cm−1 region from HCN molecules produced when CN radicals abstract a hydrogen atom from ethane, propane, and chloroform. From these observations the nascent vibrational distributions of the HCN produced were derived. The nascent vibrational population distributions of the product HCN in all of the reactions are non-statistical and inverted in both the pure CH stretch (00p) and CH stretch—bend (0np) series. 相似文献
77.
Gerald W. Evans Robert Fairbairn 《The Journal of the Operational Research Society》1989,40(11):971-981
A 0-1 integer linear programme for the selection and scheduling of US National Aeronautics and Space Administration (NASA) missions over a long planning horizon is presented. This model was formulated to allow a higher-level user-interaction with an advanced missions database currently being developed. The model implicitly considers the multi-objective nature of the problem, which results from the desire to maximize benefits in several categories as well as from the desire to minimize cost. In addition, the model allows the planner much flexibility in the selection process. This is accomplished by allowing the planner the ability to specify long- or short-term budget constraints, precursor/follow-on mission requirements, or any number of other idiosyncratic constraints which might be of importance in the decision process. Small example problems are solved in order to illustrate the approach, and areas for further research are discussed. 相似文献
78.
Pawan K. Agarwal Richard T. Garner William W. Graessley 《Journal of Polymer Science.Polymer Physics》1987,25(10):2095-2111
We present an analysis of data on the intrinsic viscosity [η] of sulfo-polystyrene ionomers in several solvents for a variety of sulfonation levels and counterions. For solvents of low dielectric constant, 2 < ε < 18, [η] decreases from the base polymer value [η]0 with increasing substitution level. This behavior was attributed to intramolecular association of ionic dipoles. The ratio [η]/[η]0 was found to depend on a single reduced variable αAαSx, where x is the fractional substitution, αA depends only on the counterion, and αS ∝ ε?1 depends only on the solvent. For solvents of high dielectric constant, 36 < ε < 47, [η] increases approximately as x3, and counterion effects are small. This behavior was attributed to ionic dissociation, giving rise to a polyelectrolyte effect. Implications of the low ε results are discussed in relation to association-induced gelation behavior and possible generalizations of the reduced variables approach. 相似文献
79.
80.
The Dirac equation is solved for two novel terms which describe the interaction energy between the half-integral spin of a
fermion and the classical, circularly polarized, electromagnetic field. A simple experiment is suggested to test the new terms
and the existence of radiation-induced fermion resonance. 相似文献