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We present a dual-infall galactic chemical evolution model which uses a new set of stellar yields calculated by Limongi et al (2001) to constrain the amount of iron-peak elements ejected by massive stars. The age-metallicity relation, G-dwarf distribution and evolution of abundance ratios are predicted using Galaxy Evolution tool (GEtool), a software package currently being developed to self-consistenly model the chemical and spectral evolution of disk galaxies. A comparison with results obtained using the Woosley & Weaver (1995) core-collapse supernova models suggests that the observed behaviour of key abundance patterns cannot be reproduced if the iron yield of massive stars increases with initial mass.

A 2.7-meter Liquid Mirror Telescope (LMT) is currently under construction at the University of British Columbia. The stationary, parabolic primary mirror is formed by uniformly rotating the highly reflective liquid, metallic mercury. Compensation for the lack of mechanical tracking will be accomplished by using the Time Delay and Integrate (TDI) readout technique with our Ford 2048 x 2048 CCD detector. The ability to produce large, diffraction-limited mirrors in the laboratory has been previously demonstrated; this project, the first of its kind, is an investigation into their potential for astronomical survey-work, in a working observatory environment. A set of 40 intermediate-band filters, one filter to be used per "photometric" night, will facilitate the collection of Spectral Energy Distributions (SEDs) of all objects, to a limiting stellar V[symbol omitted] ~21, in the 83.0 deg² strip (1/3 deg wide) available to this telescope. A catalog of >10⁵ galaxy and ~3,000 quasar SEDs is expected, providing the largest database of its type to date. A detailed stress-tensor analysis of the mercury-loaded mirror cell is given. The maximum flexure of the cell (at the mirror rim) was found to be ≲0.32 mm. The high resonant frequency of the cell was designed to minimise the excitement of both gravity and capillary waves, surface phenomena which can degrade image quality. An analysis of the support structure indicated that its maximum deflection under wind loading (≲0.3µm) would be significantly less than the Ford CCD's physical pixel size of 15 µm. Temperature-sensitive autofocussing was needed to ensure that thermal expansion/ contraction of the support structure did not lead to defocussing. Star-trail curvature at non-zero latitudes and the discrete nature of the TDI readout mode leads to elongation of north-south (NS) and east-west (EW) image structure, respectively. Convolving stellar Point Spread Functions (e.g. Gaussian) with the CCD's pixel width showed image broadening of ~5% (EW) and ~9% (NS). While these effects are expected to be negligible for our instrument, quantifying them under on-site testing will be imperative before proceeding with the development of larger LMTs.

Bovine Somatotropin (BST) is a naturally occurring hormone in dairy cows which affects milk production levels (Chalupa and Galligan, 1988). The effects of BST have been known since the 1930's but limited supply of this hormone made any large scale commercial use impossible. Recently a low cost source of BST became available through recombinant DNA technology. This low cost availability of the hormone has led to research experiments which show that recombinant BST can significantly increase a cow's ability to produce milk (Peel and Bauman, 1987; Burton et al, 1987; Soderholm et al, 1988; De Boer et al, 1988). A number of studies have examined the firm level impacts of BST on the Canadian dairy industry. This present work will build upon these earlier studies by examining the impacts of BST at the both the firm and aggregate levels for all of the dairy producing regions in Canada. To facilitate this analysis at an aggregate level a linear programming model of the Canadian dairy industry was used. This model describes the dairy sector for each province, including the production, processing, trade and marketing subsectors, and is incorporated into the Canadian Regional Agricultural Model (CRAM), (Webber et al, 1986). Several scenarios were examined representing different government policy responses with the introduction of BST to the Canadian dairy industry. These scenarios are compared to a 1986 "base case" situation of the dairy industry. The first scenario examined represents a "no policy change" situation. Provincial quota levels, producer prices, levies and subsidies all remain unchanged and BST adoption rates are assumed for each province. In order to maintain existing milk production levels with BST a 5% reduction in the national cow herd results. This lower number of animals producing the same amount of milk as in the base case results in a 5% increase in dairy producer income at the national level. In the second scenario the impact of BST on quota values is examined. As in the first scenario all dairy policy instruments remain at 1986 base levels. The decrease in marginal costs for a producer fully adopting BST is then estimated. Using a marginal cost estimate of $32 per hi, the fall in marginal cost was nearly 6% or $2.00 per hi on average for Canada. This results in an 18% increase in what these producers can pay for quota. Using lower marginal cost estimates would result in a greatre increase in this variable and smaller quota increases. In scenario 3 some of the benefits of BST adoption are passed on to consumers. This is done by allowing production levels to expand such that the difference between farm-gate price and supply price remains the same as prior to the introduction of BST. Quota values remain at their base case level. This resulted in a 2% increase in the national supply of raw milk. In the fluid milk market the supply of standard milk increased by 2% and lowfat milk production increased by approximately 3 percent. In the industrial market cheese production increased by 6%, butter production increased by 2% and skim milk powder production fell by approximately 4 percent. In the final scenario the benefits of BST adoption are passed on to the taxpayers. This is accomplished by reducing the dairy subsidy by an amount which just offsets the cost savings in each province as a result of BST adoption. This leads to a decrease in the dairy subsidy of $80 million at the national level or approximately 30% of the 1986 subsidy payment. At the firm level, given the assumptions of this study, the main impacts of BST are a fall in marginal costs of $2 per hi and an increase in quota values of 18%. While these estimates of firm level changes resulting from BST adoption are not trivial they are much less than would be expected with earlier results of milk yield increases of over 25 to 3 5% accompanied by dry matter feed increases of only 10 to 15 percent (Bauman et al, 1985; Soderholm et al, 1988) . Given the assumed Canadian adoption rates of approximately 50% the aggregate level impacts of BST are more moderate. The national herd size falls by 5% and dairy producer incomes are increased by 5% to produce at the base case 198 6 production levels.