Throughout the last glacial period, massive volumes of icebergs were discharged periodically from the Hudson Strait region during so-called Heinrich (H) events depositing sediments in distinct layers across the North Atlantic as they melted. The objective of this research was to measure and describe sedimentation associated with a meltwater plume discharged during the H1 ice-rafting event (14–19 ka) by examining sediment texture. The H1 layer was sampled in 11 piston cores that cover about 4000 km of the slope between Hudson Strait and the Bay of Fundy and range in water depth from 818–2740 m. Disaggregated inorganic grain size (DIGS) distributions were determined using a Coulter Counter. Additionally, carbonate content and the coarse fraction were measured and DIGS spectra were parameterized using an inverse ?oc model and sorted using entropy analysis. Results suggest that H1 layer sediments were mainly delivered by plume, ice-rafting and turbidity currents. In general, plume deposition was only significant proximally and distal sediments were mainly delivered by ice-rafting. However, the lack of plume deposited sediments distally does not necessarily imply the absence of a plume.

A species threshold was used to assign unidentified Hymenoptera into DNA barcode Operational Taxa (DbOT) for both an assessment of species richness in rose gall communities and as part of a broad scale survey of genome size diversity. The species threshold of 2.2% was calculated from minimum interspecific divergence of DNA barcode (COI, mtDNA) and internal transcribed spacer region 1 (ITS1, rDNA) sequences from both identified and unidentified Hymenoptera associated with rose galls induced by Diplolepis (Cynipidae). Analysis of both DNA barcodes and ITS1 sequences suggested that several described species of Diplolepis (Cynipidae), Periclistus (Cynipidae), and Torymus (Torymidae) require re-examination to define species boundaries. It was also determined that the total number of DbOTs is higher than previous estimates of species richness of Hymenoptera associated with rose galls induced by Diplolepis. Additionally, genome size estimations were determined for 51 DbOTs from all eight families of Hymenoptera associated with rose galls induced by Diplolepis, five of which did not have any previous genome size estimates. A subsequent large-scale survey of Hymenoptera enabled by the use of the DbOT approach produced genome size estimations for 309 DbOTs from 36 families in 13 superfamilies. It was shown that Hymenoptera do not have smaller genome sizes than other holometabolous orders, and that a parasitoid lifestyle does not appear to constrain genome size. The suggested positive relationship between genome size and development time was investigated by comparing mean genome size of taxa with known or apparent differences in development rate. It was concluded that statistical comparisons between taxa that are grouped in broad categories would be unlikely to detect significant differences in mean genome size because the range of biological features within such categories is highly variable. However, comparisons between interacting groups with narrowly defined development strategies determined that mean genome size was statistically smaller in taxa that obtained resources within a narrow window of opportunity. This result suggests that rapid development in relation to competitors may be important in species of Hymenoptera with higher mortality risk.

No description available.

No description available.

Sexual size dimorphism (SSD), or the difference in body size between males and females, is common in almost all taxa of animals and is usually assumed to be adaptive. Darwin's two main mechanisms for the evolution of SSD, sexual selection for larger males and fecundity selection for larger females, have often been demonstrated. However, males and females frequently share both genes and environment and more recent papers have noted that males and females must experience differences in lifetime selection on body size for SSD to be maintained. Over two generations I examined lifetime selection acting on adult body size (total length) in a common insect where females are larger than males, the waterstrider Aquarius remigis. Both fecundity selection for larger females and sexual selection for larger males are occurring in this species and both selective forces appear to target specific components of body size rather than total length; sexual selection targeting male genital length and fecundity selection targeting female abdomen length. While body size did not appear to influence adult prereproductive survival, longevity during the reproductive season was negatively related to body size for both sexes. When the opposing selection of reproductive success and reproductive longevity are combined, both males and females have an intermediate optimum body size. A remarkable result of this stabilizing selection was that the optimum size of males was smaller than that of females. I also examined the repeatability of reproductive success in both sexes and the trade-off between egg size and egg number. Finally, estimates of the quantitative genetic basis of the traits examined indicate that both male and female body size, and components of body size, are heritable and can respond to the selection detected. Components of body size in A. remigis are variable in both the degree and direction of sexual dimorphism and the genetic analysis indicates partial isolation of dimorphic and

This thesis is based on observations of the physical properties of wheat flour dough using ultrasonic measurements. Three frequency ranges were used in the study, low frequencies (near 40 kHz), intermediate frequencies (1 to 5 MHz, where bubble resonance effects are apparent), and high frequencies (near 20 MHz). Doughs mixed under different head space air pressures, from vacuum to atmospheric pressure, as well as under nitrogen, were studied at low frequency to investigate their relaxation behavior. Subsamples from ambient dough and vacuum dough displayed differences in the dependence of velocity and attenuation on time after compression, but no post mixing relaxation effect was apparent. A critical headspace pressure of approximately 0.16 atmospheres determined whether vacuum-like or ambient-like relaxation was observed. A peak in attenuation and changes in ultrasonic velocity were observed around the bubble resonance frequency, and these ultrasonic parameters changed substantially as a function of time. A bubble resonance model was used to interpret the results around the bubble resonance frequency, and bubble size distributions were estimated for ambient and vacuum dough from the ultrasonic data. For the high frequency range, a molecular relaxation model was used to interpret the results. Different fast relaxation times were observed for ambient dough (5 ns) and vacuum dough (1 ns). This relaxation time may be associated with conformational rearrangements in glutenin inside the dough matrix. These experiments have enabled dough relaxation to be probed over a very wide range of time scales (from ns to hours), and will lead to a better understanding of the role of dough matrix and gas cell effects on the physical properties of wheat flour doughs.

Farmers in Western Canada are continually assessing where to invest their next dollar. In considering a farm expansion and the machinery assets they need to match their current farm size or a possible expansion. This study attempts to find the optimal farm size by creating a farm budget model that maximizes profit over a range of different farm sizes. As farm size increases there is more risk that inclement weather will lengthen the time needed for crop operations. Previous studies have shown that both seeding and harvest operations have optimum time windows in which they should occur for best yield results. The results of this research showed that net mean profit was maximized around a 9,000 acre grain farm. For farm sizes above 9,000 acres losses associated with lack of field operation time could not be compensated by cropping additional acres.

No description available.

No description available.

This study of Fertility Differentials in Bangladesh is based on a subset of data obtained from the 1983 Bangladesh Contraceptive Prevalence Survey. The focus of the study is to identify the variables that significantly affect the cumulative fertility of women in Bangladesh and to examine differentials in fertility.Path analysis has been used for analyzing the data of this thesis. Differentials in fertility are examined in terms of selected demographic and socio-economic characteristics of the ever married women and their husbands.The study shows that age of women has the highest effect on number of children ever born. Religion has positive and significant direct effects on fertility. Education of women has significant negative effects on fertility. Employment status of women effect fertility negatively in rural Bangladesh. The results of this study also suggest that high fertlity in Bangladesh will persist if immediate action is not taken to halt it. / Department of Mathematical Sciences