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L'histoire vecue du desastre de la mine Springhill raconte l'etablissement et l'organisation d'un centre de secours et la participation dans ce desastre de l'equipe psychiatrique.Les auteurs decriv...

The de Haas-van Alphen effect has been measured in single crystals of ytterbium at 1.2°K in magnetic fields up to 116 koe. The crystals, prepared by distillation, were found to be in either a hexagonal or a f.c.c. phase at room temperature but only in the hexagonal phase after a cooling cycle to 1.2°K. The hexagonal phase is attributed to a hexagonal-close-packed structure reported previously for ytterbium at temperatures above 260°C. De Haas-van Alphen frequencies for the h.c.p. principal planes and symmetry directions are reported. These results indicate hyperbolic sections of the Fermi surface of h.c.p. ytterbium.

The de Haas\char22{}van Alphen (dHvA) effect was used to measure the Fermi surfaces of pure antimony and antimony alloys with up to 0.29-at.% tin. At the highest concentration, the hole dHvA frequencies increased by 75% and the electron frequencies decreased to less than half of the pure-antimony values. Cyclotron masses of electrons and holes at absolute frequency minima increased and decreased for holes and electrons, respectively, giving a definite indication of nonparabolic conduction and valence bands. A comparison of the hole- and electron-Fermi-surface volumes with the number of tin atoms added showed that one tin atom removes one electron from the alloy as expected from the unit valence difference between antimony and tin. This result corrects that found by other workers using different techniques. Extrapolation of the hole and electron densities in the alloys indicates that the electron pocket will be empty at \ensuremath{\sim} 0.35-at.% tin while the hole pocket will disappear at about the same concentration of a hexavalent element such as tellurium. The rigid-band predictions without any corrections for changes of lattice parameter describe the observed frequency shifts quite well at low concentrations. At higher values there is a deviation caused by the mass and Fermi-surface-shape changes. The Fermi-surface shape and cyclotron mass are also discussed in terms of a band structure determined from the Falicov\char22{}Lin pseudopotential.

Dr. J. L. Asseistine, Man.; Dr. Daniel Blain, Wash., D. C.; Dr. Paul Christie, Ont.; Dr. L. I. M. Coleman, Ont.; Dr. F. A. Dunsworth, N. S.; Dr. Robert S. Garber, N. J.; Dr. C. H. Gundry, B. C.; Dr. William S. Hall, S. C.; Dr. C. J. C. Kennedy, N. Y.; Dr. Ernest S. Klein, Ill.; Dr. Thaddeus P. Krus/i, Neb.; Dr. B. H. McNeel, Ont.; Dr. S. R. Montgomery, Ont.; Dr. H. C. Moorhouse, Ont.; Dr. P. 0. O’Reilly, Sask.; Dr. John Rich, Ont.

Studies were conducted in 189 oral surgery out-patients to evaluate the combination of meperidine hydrochloride and diazepam for anesthesia and to determine its effect on the cardiovascular and pulmonary systems. Results showed that neither ventricular cardiac arrhythmias nor clinically significant respiratory depression occurred in the sedated patients; meperidine-diazepam proved to be satisfactory for oral surgical procedures.

The de Haas-van Alphen effect has been used to measure the Fermi surface areas, cyclotron masses and Dingle temperatures in antimony and its alloys containing less than 0.3 percent tin. The Fermi surface of each alloy was similar to the pure antimony surface. However the hole surface increased in size and the electron surface shrunk since tin removes electrons from the alloy. The cyclotron masses increased and decreased for holes and electrons respectively, giving a definite indication of nonparabolic conduction and valence bands. The cyclotron masses were found from the temperature dependence of the dHvA amplitude after interfering dHvA frequency components were removed by a Fourier analysis technique. The Dingle temperature increased roughly linearily with tin concentration. A comparison of the hole and electron Fermi surface volumes with the number of tin atoms added to the alloys shows that one tin atom removes one electron from the alloy as expected from the unit valence difference between antimony and tin. This value is higher than that found by other workers using different techniques. The shapes of the energy bands along with the cyclotron masses have been compared with several band models. An ellipsoidal band provides a rough overall description of both holes and electrons while an ellipsoidal nonparabolic band describes the mass behaviour on alloying more accurately. A pseudopotential band calculated using the method and potential of Falicov and Lin (1967) was also compared with the data. The observed relative frequency changes were used to compare the data with the rigid band model of alloying. The bands are rigid for low concentrations. At higher concentrations there are deviations apparently caused by the cyclotron mass change and an axial ratio change in the hole Fermi surface. Thesis Doctor of Philosophy (PhD)