This thesis has used medium- and high-resolution spectral data to derive elemental abundances, in particular light and heavy s-process elemental abundances, for groups of giant stars in the globular clusters 47 Tuc, NGC 6388 and NGC 362. These analyses were undertaken using both curve-of-growth and spectrum synthesis techniques. The techniques were calibrated with respect to the metal-poor giant star Arcturus in order to reduce systematic errors in the analysis process. A feasibility study was undertaken that compared synthetic spectra at different resolutions throughout the colour-magnitude diagram (CMD) of a metal-rich ([Fe/H] = -0.5 dex) globular cluster. This study identified where on the CMD light and heavy s-process elemental abundances could be derived at medium resolution (R ~ 10,000). Abundance analyses could be undertaken on the giant branches down to just below the horizontal branch and then again on the main sequence below Teff ~ 4500 K. At all other places on the CMD high-resolution spectra (R ~ 30,000) are required to derive these abundances. Performance verification data at R ~ 5,000$ was obtained using the Robert Stobie Spectrograph (RSS) on the Southern African Large Telescope (SALT) and showed that there were no large scale s-process elemental abundance variations in 47 Tuc giant branch stars. The level of precision in this preliminary data was [X/Fe] ~ 0.5dex. A resolution of R ~ 10,000 should be achievable with SALT RSS in the future which will improve this limit. The AAOmega survey of 47 Tuc stars at R ~ 6,500 was more promising in certain aspects of elemental abundance determination. The observed wavelengths included the key features of CN and CH molecular bands, and light (Z < 30) and heavy (38 < Z < 63) element spectral lines. CN indices were measured and calibrated to previous results. The well-known CN bimodality was observed in the 47 Tuc stars, as well as a radial gradient in CN strength. A preliminary subset of ten of the survey stars have undergone an abundance analysis for which the abundances of Fe, Si, and Ca were found to be homogeneous within this cluster. The Na abundances had a large range in values that were observed to correlate with CN strength. The s-process elemental abundance results were inconclusive. The Zr abundances showed little to no enhancement in the sample and the Ba abundances varied considerably due to strong lines of Ba II being extremely sensitive to microturbulence. Various high-resolution studies were carried out using spectra of giant stars in 47 Tuc, NGC 6388 and NGC 362 observed on the Australian National Observatory (ANO) 2.3 m echelle spectrograph and the Ultra-Violet Echelle Spectrograph (UVES) on the Very Large Telescope (VLT). The high-resolution analysis of 47 Tuc giant star Lee 2525 found an enhanced Zr abundance in this star which resolved a discrepancy between two previous 47 Tuc elemental abundance studies (Brown & Wallerstein 1992; Wylie et al. 2006). The stars in the VLT dataset that were analysed here included five giant branch stars in 47 Tuc, two in NGC 6388 and thirteen in NGC 362. The low temperatures and gravities of these stars caused departures from local thermodynamic equilibrium in low excitation potential neutral species, particularly Fe and Zr, that needed to be taken into account before reliable stellar parameters and elemental abundances could be determined for these stars. Veiling effects due to circumstellar dust were postulated to have produced artificially low metallicities for the infra-red excess stars in this sample, particularly for the 47 Tuc stars. The element abundance analyses of 47 Tuc, NGC 6388 and NGC 362 stars found the derived metallicities to be homogeneous for each cluster (<[Fe/H]>(47Tuc) = -0.88 +/- 0.09 dex; <[Fe/H]>(NGC6388) = -0.60 +/- 0.06 dex; <[Fe/H]>(NGC362) = -1.21 +/- 0.08 dex). The 47 Tuc sample included Lee 2525 and the five VLT stars. The derived metallicities were in reasonable agreement with previously reported values. The light (ls) and heavy (hs) s-process element abundances were enhanced and homogeneous in the stars of each cluster. The abundances determined for 47 Tuc and NGC 6388 were in good agreement, reflecting the similarity in metallicity of the stars in these two clusters (<[ls/Fe]>(47Tuc) = +0.53 +/- 0.02 dex; <[hs/Fe]>(47Tuc) = +0.40 +/- 0.06 dex; <[ls/Fe]>(NGC6388) = +0.58 +/- 0.13 dex; <[hs/Fe]>(NGC6388) = +0.39 +/- 0.07 dex). The more metal-poor cluster NGC 362 was less enhanced in ls elemental abundances and slightly more enhanced in hs elemental abundances (<[ls/Fe]>(NGC362) = +0.32 +/- 0.10 dex, <[hs/Fe]>(NGC362) = +0.46 +/- 0.09 dex). The clear enhancement in the s-process elemental abundances and homogeneity in the results for each globular cluster is evidence that these stars have been enhanced extrinsically in s-process elements. Pollution events in the history of each cluster has resulted in the abundance distribution in both the light elements and the heavy elements that has been observed in the stars analysed in this thesis. The enhancements in Na, ls and hs elemental abundances favours intermediate mass AGB stars as the source of the pollution.

In order to understand the origin of globular clusters, large samples of their stars need to be observed and analyzed for their chemical composition. This is especially true for the complex, multimetallic cluster ω Centauri, with its large range of iron, carbon, nitrogen, oxygen, sodium and barium abundances. In order to accomplish this, an automated spectral matching pipeline was developed to determine these abundances. This thesis made use of photometry and low resolution spectroscopy to analyze the chemical composition of evolved stars in three clusters: ω Cen, 47 Tuc and NGC 6752. The latter two clusters are monometallic and selected due to their similar metallicities to the metal-rich and metal-poor stars in ω Cen. This allowed them to be used as test-cases for the spectral matching pipeline. For ω Cen, two analyses were performed. In the first, 221 giant branch stars were selected that had known [O/Fe]. These stars showed the expected anticorrelation in [C/Fe]to [N/Fe]. In the second, spectral indices were used to estimate the oxygen abundance of the stars, leading to a determination of whether a particular star was oxygen-rich or oxygen-poor. From this a catalogue of abundances of iron, carbon and barium of 848 giant branch stars were determined, of which 557 also had well-defined nitrogen abundances. k-means clustering analysis was used to group the stars in ω Cen into four homogeneous groups based upon these abundances. These groups suggest that there were at least four main periods of star formation in the cluster. The exact order of these star formation events is not yet understood, with some models predicting the groups formed from iron-poorest to iron-richest, while others suggest the potential for iron-poorer groups to form after iron-rich groups. These results compare well with those found from higher resolution studies and show the value of more extensive lower resolution spectral surveys. They also highlight the need for large samples of stars when working with a complex object like ω Cen.

In this thesis, investigations into the suitability of three 'weak-link' models, designed for the simulation of superconducting cluster systems, are reported. The focus of the investigation is on both the accuracy of the transport properties produced by these models, and the time taken to produce their results. The thesis develops the theory behind a previous approach which was exclusively used to model percolation systems for coverages below the critical coverage. The modifications made allow the simulations to extend to system coverages above the critical coverage. An additional 'current-ramping' algorithm, to simulate the systematic increase or decrease of current forced through the system, is described and explored. The results for the three models are compared, and their suitability for future investigations is discussed.

The gene that produces the precursor RNA transcript to the three largest ribosomal RNA molecules (rDNA) is present in multiple copies and organized into gene clusters. They represent 0.5% of the diploid human genome but are critical for cellular viability. The individual genes possess very high levels of sequence identity and are present in high local concentration, making them ideal substrates for genomic rearrangement driven by dysregulated homologous recombination. Our laboratory has developed a sensitive physical assay capable of detecting recombination-mediated genomic restructuring in the rDNA by monitoring changes in lengths of the individual clusters. In order to determine whether dysregulated recombination is a potential driving force of genomic instability in human cancer, adult patients with either lung or colorectal cancer, and pediatric patients with leukemia were prospectively recruited and assayed. Over half of the adult solid tumors show detectable rDNA rearrangements relative to either surrounding non-tumor tissue or normal peripheral blood. In contrast, there is a greatly reduced frequency of alteration in pediatric leukemia. This finding makes rDNA restructuring one of the most common chromosomal alterations in adult solid tumors, illustrates the dynamic plasticity of the human genome, and may have prognostic or predictive value in disease progression.

In this study I present two N-body computer simulations of the Bullet Cluster (1E 0657-56) merging system. The models are fully self-consistent, meaning that all gravitational forces are determined by the distribution of the particles. Initial positions and velocities of the two clusters are determined by solving a two-body problem. Post-collision time period shows an increase in the line-of-sight velocity dispersion in both clusters, and is consistent with previous Bullet Cluster studies. I also investigate the temporal evolution of the average cluster radial velocities of the galaxies located in the inner, middle, and outer regions of the clusters. I show that the orbital trajectories differ in pre- and post-collision periods. Inner region galaxies receive an impulse that moves them outward from the cluster center immediately after collision, while at the same time the outer region galaxies are pulled back towards the cluster center. / Department of Physics and Astronomy

There is no abstract available for this thesis. / Department of Physics and Astronomy

Influenza is a population health issue in Canada, with an annual infection rate of 10-25% of the population. The purpose of this thesis was to analyze influenza-like illnesses (ILI) from 2004-05 through to 2008-09, both spatially and temporally, throughout the province of Manitoba. The analysis used a framework specific to spatial analysis, and incorporated the principles of population health and ecological frameworks. The underlying objectives of the research were to better understand the patterns of ILI diagnoses as well as the characteristics of those diagnosed. Maps were created to show the results from various perspectives and negative binomial regression analysis was used to test which, if any, of the chosen variables were significant. Based on this research, one could conclude that although clusters of ILI do exist in Manitoba, a clear relationship does not exist between the determinants of health and ILI.

Campylobacter species are the primary cause of bacterial food-borne diarrhoea worldwide. Comparative genomic analyses of Campylobacter strains reveal genome plasticity providing insight into the evolution of virulence traits. The goal of this study was to identify genes important for infectivity and for naturally occurring variability in phenotypic traits in C. jejuni and C. coli strains. Transcriptome and phenotype analyses were conducted to determine if genetic and phenotypic characteristics could be attributed to the source of the strains. Isolates from water sources had higher biofilm formation than animal strains. Clinical strains had decreased sensitivity to hydrogen peroxide as well as increased adherence and invasion when compared to animal strains. A number of genetic differences were observed; however, without further analysis it is difficult to determine which of these impact virulence in Campylobacter. Ultimately, this project will lead to the identification of markers associated with strains of Campylobacter causing illness.

An examination of 14 indexes for determining the number of clusters is conducted on artificial binary data sets being generated according to various design factors. To provide a variety of clustering solutions the data sets are analyzed by different non hierarchical clustering methods. The purpose of the paper is to present the performance and the ability of an index to detect the proper number of clusters in a binary data set under various conditions and different difficulty levels. (author's abstract) / Series: Working Papers SFB "Adaptive Information Systems and Modelling in Economics and Management Science"

Clusters of galaxies are the largest and most massive gravitationally bound objects in the universe. They contain several hundreds to thousands of galaxies orbiting in the gravitational potential well of the cluster. The space between galaxies is filled with a hot plasma that loses its thermal energy via X-ray emission. In the absence of heating sources in the ICM, the radiative cooling of the gas leads to a significant accumulation of cold gas in the cluster core which then should ultimately condense into stars or cold gas clouds (e.g.. Fabian 1994). However, high-resolution X-ray spectroscopy of the hot intracluster gas has revealed that there is little or no signature of significant cool gas in the cluster core. This strongly suggests that there must be other forms of heating mechanisms that offset radiative losses in the intracluster medium (ICM). In this dissertation, we focus on one of the potential heating sources in the ICM, and that involves the kinetic energy in the orbital motions of cluster galaxies. We examine in detail the effects of the heating due to dynamical friction of galaxies on the evolution of the ICM. We find that galaxy heating is immaterial in systems that are in cool core configurations with no other heating mechanisms operating in the ICM. Accordingly. dynamical friction-mediated heating can not be the only heating mechanism in galaxy clusters. The situation is, however, completely different if the systems have experienced sufficient amounts of energy input to warm or hot cores. We show that the role of dynamical friction heating in moderating radiative cooling cannot be neglected in these systems. We also address the results of the last generation of non-radiative cosmological simulations of galaxy clusters (Voit et al. 2005). According to these studies, the radial entropy distribution of the simulated clusters tends to follow a power law at large radii, with cores present in the entropy configurations of these systems at small radii. The origin of the entropy cores is presently unclear. We argue that the generation of entropy cores in non-radiative simulated clusters is the result of galaxy stirring.