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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
261

A KLEINIAN APPROACH TO FUNDAMENTAL REGIONS

Hidalgo, Joshua L 01 June 2014 (has links)
This thesis takes a Kleinian approach to hyperbolic geometry in order to illustrate the importance of discrete subgroups and their fundamental domains (fundamental regions). A brief history of Euclids Parallel Postulate and its relation to the discovery of hyperbolic geometry be given first. We will explore two models of hyperbolic $n$-space: $U^n$ and $B^n$. Points, lines, distances, and spheres of these two models will be defined and examples in $U^2$, $U^3$, and $B^2$ will be given. We will then discuss the isometries of $U^n$ and $B^n$. These isometries, known as M\"obius transformations, have special properties and turn out to be linear fractional transformations when in $U^2$ and $B^2$. We will then study a bit of topology, specifically the topological groups relevant to the group of isometries of hyperbolic $n$-space, $I(H^n)$. Finally we will combine what we know about hyperbolic $n$-space and topological groups in order to study fundamental regions, fundamental domains, Dirichlet domains, and quotient spaces. Using examples in $U^2$, we will then illustrate how useful fundamental domains are when it comes to visualizing the geometry of quotient spaces.
262

Fuchsian Groups

Anaya, Bob 01 June 2019 (has links)
Fuchsian groups are discrete subgroups of isometries of the hyperbolic plane. This thesis will primarily work with the upper half-plane model, though we will provide an example in the disk model. We will define Fuchsian groups and examine their properties geometrically and algebraically. We will also discuss the relationships between fundamental regions, Dirichlet regions and Ford regions. The goal is to see how a Ford region can be constructed with isometric circles.
263

An Investigation of Migraine Candidate Genes and Genomic Susceptibility Regions

Lea, Rod A., n/a January 2003 (has links)
Typical migraine, comprised of migraine with aura (MA) and migraine without aura (MO), is a chronic, painful and debilitating neurovascular disease which is generally characterised by recurrent attacks of severe headache usually accompanied by nausea, vomiting, photo and phonophobia. Migraine has been shown to affect a large proportion of Caucasian populations with a recent comprehensive study indicating that around 25% of women and 8% of men suffer from the disease. Strong familial aggregation of typical migraine and an increased concordance for the disease in MZ twins over DZ twins, suggests that it has a significant genetic component. Heritability estimates are calculated to be between 40% and 60%, indicating that disease variation, in part, is explained by environmental determinants. The mode of transmission of typical migraine is not clear but is most likely multifactorial. Although the MA and MO subtypes exhibit some clinical heterogeneity, segregation analysis has suggested that there may be a common genetic aetiology for MA and MO, and a major gene contributing to typical migraine pathogenesis. This idea is substantiated by the fact that both subtypes of migraine can occur within the same family and even within the same individual, with up to 33% of sufferers experiencing both types of the disease. In addition, migraine prophylactics have been shown to result in similar effects in patients treated for both types of migraine. However, whether the two subtypes are truly separate entities or not remains unclear. At present, the type and number of genes involved in typical migraine is not known. Despite this, several studies into Familial Hemiplegic Migraine (FHM), a very severe subtype of MA, have led to the discovery that mutations in a brain specific calcium channel subunit gene (CACNA1A) located on chromosome 19, cause FHM in about 50% of affected families. FHM is a rare disease and is distinguished from typical migraine by its association with hemiparesis and clear autosomal dominant mode of inheritance. However, certain clinical features are common to both FHM and typical migraine including similarities in headache characteristics and triggers. Hence, FHM genetic studies provide a valuable model for investigating the genes involved in the more prevalent types of migraine with and without aura. For this reason the Genomics Research Centre has been conducting linkage studies utilising large Australian migraine pedigrees with a focus on the known FHM (CACNA1A) gene region on chromosome 19p13. Our results to date have indicated suggestive linkage to the FHM region on 19p13 in a large multigenerational pedigree (MF1) affected with typical migraine, with a maximum parametric LOD score of 1.92 (P = 0.001) obtained for a triplet repeat polymorphism situated in exon 47 of the CACNA1A gene. Expansion of this repeat was not observed, but is possible that mutations elsewhere in the CACNA1A gene may be responsible for migraine in this pedigree. To investigate this possibility, the current research involved sequencing two patients carrying the critical susceptibility haplotype surrounding the CACNA1A gene. The results of this mutation screen revealed no disease causing mutations or polymorphisms in any of the 47 exons screened. To determine whether the CACNA1A genomic region was implicated in typical migraine susceptibility in the general Caucasian population, 82 independent pedigrees and a large case-control group were also analysed using highly polymorphic microsatellite markers. There was no linkage or association detected in these groups and thus, it was concluded that if CACNA1A plays a role in typical migraine it does not confer a major effect on the disease. However, subsequent case-control studies of SNPs in the INSR gene, which is located ~15cM telomeric from CACNA1A, provided evidence of association to typical migraine. Thus, the INSR gene may now emerge as the new migraine susceptibility gene in this genomic region on chromosome 19. Family linkage studies conducted by Gardner et al have implicated an additional FHM susceptibility region on chromsome 1q31. Furthermore, independent research carried out by Ducros et al. has indicated a second FHM locus at 1q21-23, which is ~ 30cM centromeric to the region reported by Gardner et al. At this stage it is not clear whether there is a single locus, or two distinct loci, on the chromosome 1q region. This research also involved a family-based linkage and association approach to investigating the FHM susceptibility region on chromosome 1q31 for involvement in typical migraine susceptibility in affected Australian pedigrees. Initial multipoint ALLEGRO analysis provided strong evidence for linkage of Chr1q31 markers to typical migraine in a large multigenerational pedigree. The 1-LOD* unit support interval for suggestive linkage spanned ~18cM with a maximum allele sharing LOD* score of 3.36 obtained for marker D1S2782, P = 0.00004. Subsequent analysis of an independent sample of 82 affected pedigrees added support to the initial findings with a maximum LOD* of 1.24 (P = 0.008). Utilising the independent sample of 82 pedigrees we also performed a family-based association test. Results of this analysis indicated distortion of allele transmission at marker D1S249 (global c2(5) of 15.00, P = 0.010) in these pedigrees. These positive linkage and association results will need further confirmation by independent researchers, but overall they provide good evidence for the existence of a typical migraine locus near these markers on Chr1q31, and reinforce the idea that an FHM gene in this genomic region may also contribute to susceptibility to the more common forms of migraine. The serotonergic system has long been implicated in the pathophysiology of migraine. Researchers have therefore focused on the serotonin receptors and the genes that code for them when investigating this disease. Although serotonin receptor agonists have proven to be effective in the treatment of migraine, there has been little evidence of a serotonin receptor gene being associated with the disorder. However, in 1998, Ogilvie et al reported that a VNTR in the serotonin transporter gene (SERT) showed altered allelic distributions in a Danish migraine population. In addition to serotonin, there has been renewed interest in the involvement of the dopaminergic pathways in migraine. This interest has gained impetus since the study of Peroutka et al who reported an allelic association between the dopamine receptor gene DRD2 and migraine with aura. Another dopamine related gene, the dopamine beta-hydroxylase gene (DBH), has been localised to Chr 9q34 and codes for the enzyme that catalyses the conversion of dopamine to norepinephrine. It therefore plays an important role in dopaminergic and noradrenergic neurotransmission. Serum levels of DbH enzyme have been reported to be elevated in migrainous patients during the headache phase of an attack. Also, significantly increased DbH enzyme activity has been observed in migraine patients during the headache-free interval. Thus, the DBH gene is another good candidate for involvement in migraine pathophysiology and, to our knowledge, has not been previously implicated in this disease. Candidate gene studies may be useful strategies for identifying genes involved in complex diseases such as migraine, especially if the gene being examined contributes only a minor effect to the overall phenotype. This research also involved a linkage and association approach to investigating neurotransmitter related migraine candidate genes. Specifically, polymorphisms within the serotonin transporter gene (SERT), the dopamine receptor gene (DRD2) and the dopamine beta-hydroxylase (DBH) gene were tested in unrelated Caucasian migraineurs and non-migraine control individuals. In addition, an independent sample of 82 families affected with migraine were examined. Unrelated case-control association analysis of a DBH intragenic dinucleotide polymorphism indicated altered allelic distribution between migraine and control groups (c2 = 16.53, P = 0.019). Furthermore, the transmission/disequilibrium test (TDT) which was implemented on the family data also indicated distortion of allele transmission for the same DBH marker (c2 = 4.44, P = 0.035). Together, these results provide evidence for allelic association of the DBH gene with typical migraine susceptibility (Fisher's Combined P-value = 0.006) and indicate that further research into the role of the DBH gene in migraine aetiology is warranted. Nitric oxide (NO) is emerging as a key molecule affecting the pain associated with migraine. Since nitric oxide synthase (NOS) enzymes catalyse the synthesis of NO, the genes that code for these enzymes are good candidates for migraine molecular genetic analysis. This research involved investigating the role of a functionally relevant bi-allelic tetranucleotide polymorphism located in the promoter region of the human inducible nitric oxide synthase (iNOS) gene in migraine aetiology. A large group of migraine affected individuals were genotyped and compared to an age and sex matched group of unaffected controls. Results of a chi-squared analysis indicated that allele distributions for both migraine cases and controls were not significantly different (c2 = 1.93, P = 0.16). These findings offer no evidence for an allelic association of the tested iNOS polymorphism with the common forms of the disease and therefore do not support a role for this gene in migraine pathogenesis. In summary, this research involved linkage and association analysis of migraine candidate genes and genomic susceptibility regions. Whilst, the known FHM gene (CACNA1A) was excluded for significant involvement in typical migraine the adjacent INSR gene has been associated. Migraine is genetically heterogeneous and the results of this research also provide good evidence that the DBH gene is involved in disease predisposition, whilst the DRD2, SERT and INOS gene were not shown to be implicated. An additional susceptibility region for typical migraine is also likely to localise to chromosome 1q31. Overall, the results presented in this thesis have contributed valuable data to the understanding of the molecular genetics of migraine with and without aura. Future research into the molecular pathophysiological mechanisms of migraine will greatly facilitate the development of more effective diagnosis and treatment strategies.
264

Reflections on ice : scattering of flexural gravity waves by irregularities in Arctic and Antarctic ice sheets

Williams, Timothy D. C., n/a January 2006 (has links)
This thesis studies the scattering properties of different types of imperfections in large Arctic and Antarctic ice sheets. Such irregularities include cracks, pressure ridges and both open and refrozen leads. The scattering by a transition region between sea ice and a very thick ice shelf, for example as is found in the Ross Sea in Antarctica, is also treated. Methods of solution are based on applications of Green�s theorem to the appropriate situation, which leads to either a single integral equation or a pair of coupled integral equations to be solved at the boundary between the ice and the sea water. Those equations over a finite interval are solved using numerical quadrature, while those over semi-infinite ranges are solved using the Wiener-Hopf method. Results calculated using different techniques are able to be checked against each other, giving us great confidence in their accuracy. In particular, the scattering by three ice sheets of different thicknesses is confirmed analytically by mode-matching coupled with the residue calculus technique. The scattering by the single irregularities is investigated partly for its own sake, and partly with the aim of using it to treat the scattering when large numbers of features are included in a single ice sheet. The principal objective of doing this is to observe the change in the general amounts of reflection and transmission as the background ice thickness is changed. There is enough variation in our results for us to conclude that there is definite potential for using the change in an incident wave spectrum after passing through a given ice field to estimate the background ice thickness.
265

Wine tourism in Australia : emergence, development and critical issues

Macionis, Niki, n/a January 1997 (has links)
Wine tourism has emerged as a strong and growing area of special interest tourism in Australia, and as such it has become an increasingly significant component of the Australian regional tourism product. The Australian Wine Foundation (1996) estimates total Australian wine tourism figures to be in the order of 5.3 million visits per annum, worth $428 million in 1995 and which is expected to grow substantially to around $1100 million by 2025. As a consequence, Australia's Federal and State Governments and regional communities (including regional associations) are recognising the benefits of promoting their wine districts as tourism attractions in their own right. While the destinational appeal of wine regions and the concept of wine tourism is generally acknowledged, research concerning wine tourism development, marketing and impacts is lacking. Therefore, this thesis examines the nature and potential of wine tourism in Australia, and documents its historical development and current status. The activities and initiatives of a number of agencies involved in wine tourism development and marketing are also critically examined, and significant wine tourism developmental issues are investigated through a case study of the Canberra District, an emerging Australian wine region. A number of developmental similarities between rural tourism and wine tourism are noted, including: a lack of tourism and marketing awareness and knowledge by practitioners, and a lack of industry integration and cohesion. These issues are compounded by the infancy of wine tourism and the dominant product focus of wine makers and the Australian wine industry, resulting in the absence of effective inter sectoral linkages. While a number of tourism agencies and wine industry associations are pursuing wine tourism development initiatives, the success and sustainability of these activities is dependent upon addressing various developmental issues.
266

Anatomy of a group in Antarctica : thesis on the physiological adaptation and health of an expendition in Antarctica, with comment on behavioural adaptation

Lugg, Desmond James January 1973 (has links)
vii, 235 leaves : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (M.D. 1974) from the Dept. of Psychiatry, University of Adelaide
267

Carbon and energy exchange of semi-arid ecosystems with heterogeneous canopy structure

Anthoni, Peter M. 20 October 1999 (has links)
Carbon and energy fluxes were measured with the eddy covariance technique above two semi-arid ecosystems, ponderosa pine and juniper/sagebrush, located in central Oregon. The two ecosystems have low LAI and a very open canopy structure. The energy closure was ~70-80% at both ecosystems, equivalent to an imbalance of 150-250 W m⁻² on cloudless summer days, when net radiation (R[subscript n]) was ~600-700 W m⁻². The lack of closure cannot be explained by the uncertainty of an estimate of available energy due to a single R[subscript n] sensor location. At the more open juniper/sagebrush ecosystem, a numerical model showed that spatial variation in R[subscript n], even for large differences in surface radiation temperature and reflection coefficient between ecosystem components (soil and vegetation), is less than 10% of measured R[subscript n]. The uncertainty in R[subscript n] at the two-layered ponderosa pine ecosystem with patches of young and old-growth trees is expected to be smaller than at the juniper ecosystem. Net carbon exchange (NEE) at the pine site strongly depends on environmental factors effecting carbon assimilation (A[subscript c]) and ecosystem respiration (R[subscript e]). A more detailed analysis of the carbon budget showed a strong negative response of carbon uptake to large vapor pressure deficits (VPD), whereas water vapor exchange (LE) was less affected. At large VPD the vegetation maintains a sustainable water flow through the soil-plant system by stomatal control of transpiration. The stomatal closure leads to limitation in A[subscript c], but LE is subject to a positive feedback from higher evaporative demand. Annual NEE of the ponderosa pine forest (200-300 gC m⁻²) was in the mid-range of reported NEE of temperate forest ecosystems, though, unusually, much of the annual carbon gain occurred during the fall through spring, because the relatively mild winters allowed carbon assimilation to occur and R[subscript e] rates were low. The information gathered at our ponderosa pine site during two years with contrasting climate suggests that the carbon uptake of the ponderosa pine ecosystem will be more sensitive to global climate change than the water vapor exchange. / Graduation date: 2000
268

Providing care in divided space : nursing in Northern Saskatchewan, 1944-1957 and beyond

McBain, Lesley Ann 23 March 2006
In 1944, the Government of Saskatchewan created the Northern Administrative District (NAD), which established Northern Saskatchewan as a spatial entity within the provincial milieu. Attention was focused on modernizing the region, and public health nursing became one of the first state-sponsored institutions to be introduced by the provincial government. By examining the day-to-day activities of nurses who worked at remote nursing outposts in Northern Saskatchewan between 1944 and 1957 and beyond, this research examines the complex internal factors involved in region-making. Nurses lived and worked amongst their patients in small remote communities, thus making them effective vehicles for promoting modernization principles through preventative and educations programs. Despite the governments intention to modernize Northern Saskatchewan, a colonial relationship emerged between the region and the rest of the province. This situation left nurses in a confusing and often difficult position, because the institution behind initiatives to modernize the region was also their employer to whom they had certain obligations. Furthermore, the colonial attitude towards the region also extended to the nursing stations and the nurses, which often frustrated their attempts to provide medical care. As such, the small cadre of nurses played an ambiguous role, both as agents of modernization, but also opponents of its egregious effects.<p> The research examines the role of nursing in region-making through two types of geography: A geography of region-making where the literature focuses on the formal process of institutionalization, and a geography of social life, where the emerging literature on the geography of nursing provides an entry point. This two-part approach provides an opportunity to use different lenses to view the processes involved in shaping Northern Saskatchewan as it emerged as a distinct northern place within Canada.
269

The Effect of an Unexpected Auditory Stimulus on the Facial Skin Temperature of the Periorbital Regions as Quantified using Thermal Imaging

Gane, Luke 07 December 2011 (has links)
Infrared thermal imaging of the periorbital regions of the face shows promise as an input signal modality for an alternative communication system for individuals with conditions that preclude speech or voluntary movement, such as total locked-in syndrome. However, it was unknown if the startle response triggers a change in the skin temperature of these regions; such a change could generate false positives in a thermography-based access system. This study presents an examination of the temperature characteristics of the periorbital regions of 11 able-bodied adult participants before and after an auditory startle stimulus. The results show that the startle response has no substantial effect on the mean temperature of the periorbital regions. This indicates that thermography-based access solutions would be insensitive to startle reactions in their user, an important advantage over other modalities being considered in the context of access solutions for individuals with a severe motor disability.
270

The Effect of an Unexpected Auditory Stimulus on the Facial Skin Temperature of the Periorbital Regions as Quantified using Thermal Imaging

Gane, Luke 07 December 2011 (has links)
Infrared thermal imaging of the periorbital regions of the face shows promise as an input signal modality for an alternative communication system for individuals with conditions that preclude speech or voluntary movement, such as total locked-in syndrome. However, it was unknown if the startle response triggers a change in the skin temperature of these regions; such a change could generate false positives in a thermography-based access system. This study presents an examination of the temperature characteristics of the periorbital regions of 11 able-bodied adult participants before and after an auditory startle stimulus. The results show that the startle response has no substantial effect on the mean temperature of the periorbital regions. This indicates that thermography-based access solutions would be insensitive to startle reactions in their user, an important advantage over other modalities being considered in the context of access solutions for individuals with a severe motor disability.

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