The importance of the cichlid teleost Tilapia mossambica as a protein source, coupled with its remarkable adaptability, has resulted in its introduction into many water systems throughout the tropical, sub-tropical and even temperate regions of the world. However, its successful exploitation of these waters is dependent very largely upon the value of minimum temperatures and their duration. For e.g. Long et al (1961) has drawn attention to the tremendous mortalities of T. mossambica that occur in shallow water bodies during the precipitous temperature decreases that accompany the winter monsoons in Vietnam and other eastern countries, even at temperatures as high as 14 or 16º C. Coehe (1967) does not recommend stocking with T. mossambica where temperatures are not above 14º C all the time. Ailanson et al (1962) conclude, after an experimental study, that low temperatures (13º C or lower) in South African highveld dams in winter are certainly an important factor in the extensive mortalities of T. mossambica that have been reported from these dams. Jubb (1961) also reports that this species is often killed during a severe winter in Rhodesia. Intro., p.1.

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The heavy alkaline earth hydrides consist of the Group II (alkaline earth metal) hydrides, namely CaH2, SrH2, and BaH2, which adopt the cotunnite-type structure at ambient pressure and temperature conditions. There has been much recent research interest in these compounds; in the past decade numerous experimental and theoretical studies exploring the hydrides in both applied and fundamental respects have been added to the literature. The present work constitutes a study of the heavy alkaline earth hydrides subjected to extreme pressure conditions (at ambient temperature). Specifically, pressure-dependent angle-dispersive powder x-ray diffraction and Raman spectroscopy experiments, as well as first-principles calculations, have been carried out to explore the structural stability, compressibility, and optical phonon spectra of the heavy alkaline earth hydrides. To complement the work on the hydrides, a companion study on BaF2---a structural analogue---is presented, as well as a description of some selected experimental techniques used to carry out the research. The powder x-ray diffraction results reveal that all of the heavy alkaline earth hydrides undergo a pressure-induced, first-order structural phase transition. The proposed Ni2ln structure for the high-pressure phase is based on both the results of first-principles calculations and an isostructural comparison with BaF2. The transition pressures and the proposed high-pressure structure are corroborated by the results of the Raman spectroscopy measurements. Where applicable, equation of state parameters from both the experimental and theoretical studios are reported, and a comparison of these respective parameters at ultra-high pressures (greater than 50 GPa) suggests that the experimentally observed bulk moduli are overestimated due to the presence of non-hydrostatic pressure conditions.

This report contains an analysis of the factors responsible for the 1949-50 winter injury to cherry, peach and apricot trees in the Okanagan Valley of British Columbia, Canada. Included in the report are sections dealing with the history of winter injury, various theories of the causes of winter injury, and a description of the many forms of injury. The non-climatic and climatic factors affecting the intensity of injury are discussed in detail. Recommendations for minimizing the susceptibility of trees to winter injury under Okanagan Valley conditions are included, together with recommendations for the care of trees after injury has occurred. Reports on the relative hardiness of specific stone-fruits are presented in some detail. The report is liberally supplied with tables indicating the extent of crop damage and tree damage in each district of the Okanagan Valley. These tables are based on observations made in over two thousand orchards. The statistical analyses are based on detailed observations carried out in over four hundred orchards. The published literature dealing with winter injury has been freely consulted, and reference is made to many of the important papers dealing with the winter injury complex. A complete bibliography is included. / Land and Food Systems, Faculty of / Graduate

Work on film flow in liquid helium II is not new, but very little has been done in the temperature region below 1 degree. The present work describes a method of extending these measurements down to the very low temperature range. After a brief introduction laying the foundation of the problem in its proper framework in the field of low temperatures, the experiments and results obtained by other workers in film flow and associated phenomena are reviewed. Then the author proceeds to the development of experimental techniques used in attempting to seal gaseous helium at high pressures in glass capsules. Chapter II terminates with a full description of the so-called Heater Method with which helium 'bombs' were sealed at pressures ranging from 750 to 1100 psi. One of these capsules containing a capillary beaker, and partially filled with manganous ammonium sulfate, was used in determining film flow rates at temperatures ranging from approximately 2° to 0.6°K, The lower temperatures were obtained by adiabatic demagnetization techniques. Chapter III is a report of such experimentation. The results obtained are much like those of Ambler and Kurti, 1952, and support their contention that film flow rates do increase with decreasing temperatures in the region below one degree absolute. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The behaviour reactions and the mechanisms involved in the injury and death of goldfish (Carassius auratus) exposed to chill temperatures have been investigated. Upon direct transfer to colder water goldfish exhibit an initial shock reaction followed by a primary chill-coma reaction with the latter reaction sometimes being followed, after apparently normal recovery, by a secondary chill-coma that ends in death. The first two reactions are believed to result from the effect of an excessive thermal stimulation of the cells of the central nervous system whereas the death that follows the secondary chill-coma is attributed to a disruption of the osmotic regulatory system. Within the range of size compared (three to ten centimeters and one to twelve grams), the tolerance to chilling temperatures of goldfish of the same or nearly the same age increases as the size of the fish increases. Statistical analysis of this relation shows a significant positive correlation between the survival times and the weight of the fish over their length as well as a significant negative correlation between the survival times and the surface area of fish over their weight. Several factors are thought to be involved in this effect of size of fish on tolerance to chill temperatures, viz., the insulation and surface area of fish relative to body mass in relation to the rate of heat loss and therefore to the body temperature; the gill surface area of fish relative to body mass in relation to the rate of abnormal osmotic passage of water subsequent to a disruption of the osmotic regulatory system. / Science, Faculty of / Zoology, Department of / Graduate

For a number of years daily observations of surface temperature and salinity have been taken at ooeanographic stations (mostly lighthouses) on the B. C. coast. The present thesis is the first attempt that has been made to systematically analyse this data. The annual variation in temperature was seen to follow the general climatological trend of the B. C. coast at each of the stations, although a wide range in the amplitudes of these periodic variations was noted. The factors influencing the amplitude of the annual temperature curves were considered and such effects as incoming radiation, the extent of turbulence, the degree of shelter and the phenomena of upwelling due to horizontal wind stress (West Coast of Vancouver Island) have been discussed for each of the stations. Correlations were made between available meteorological information and the sea temperature observations and an attempt has been made to determine temperature contours of the B. C. coastal waters during the summer when the surface temperature is least uniform. The salinity observations were treated in an analogous manner to temperature and found to exhibit characteristic periodic annual variations. The stations were classified by means of these variations and the influences of precipitation and fresh water runoff, evaporation and mixing were discussed and correlations with meteorological observations were again made. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

An attempt has been made to follow some of the metabolic changes occuring during acclimation of goldfish (Carassius auratus) to temperature. The goldfish were acclimated to certain temperatures and then reacclimated to different temperatures. The change in the unsaturation of their body fats was found using Wij's iodine value determinations. The fats of goldfish fully acclimated to different temperatures show different iodine values. In general the fats are more saturated at higher temperatures. Changes in the amount of unsaturation during the acclimation process have been followed. It has been found upon increase in temperature there is a decrease in the amount of unsaturation. / Science, Faculty of / Zoology, Department of / Graduate

Measurement of turbulent fluctuations of wind temperature and humidity to determine the momentum, sensible heat and latent heat surface fluxes were made in Bimini Island, in April - May 1971 over Grand Bahamas Banks. The temperature spectralshape and WT cospectral shape showed strong time dependency. The temperature and humidity turbulent fluxes were dissimilar some of the time as in the case of B.O.M.E.X. This dissimilarity and time dependency of the spectra and cospectra depend on the structure of the vertical profile of deeper layers which is determined by the evolution of the tropical inversion layer. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate