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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.
41

Computational methods for domination problems

Bird, William Herbert 04 October 2017 (has links)
For a graph G, the minimum dominating set problem is to find a minimum size set S of vertices of G such that every vertex is either in S or adjacent to a vertex in the set. The decision version of this problem, which asks whether G has a dominating set of a particular size k, is known to be NP-complete, and no polynomial time algorithm to solve the problem is currently known to exist. The queen domination problem is to find the minimum number of queens which, collectively, can attack every square on an n by n chess board. The related border queen problem is to find such a collection of queens with the added restriction that all queens lie on the outer border of the board. This thesis studies practical exponential time algorithms for solving domination problems, and presents an experimental comparison of several different algorithms, with the goal of producing a broadly effective general domination solver for use by future researchers. The developed algorithms are then used to solve several open problems, including cases of the queen domination problem and the border queen problem. In addition, new theoretical upper bounds are presented for the border queen problem for some families of queen graphs. / Graduate
42

The evolution of the native land mammals of the Queen Charlotte Islands and the problem of insularity

Foster, J. Bristol January 1963 (has links)
The Queen Charlotte Islands are the most isolated islands in British Columbia and are populated by eight species of indigenous land mammals, all except one of which are represented by at least one endemic form. Geological and botanical evidence lend strong support to the hypothesis that the Islands could have been a refuge to most of these mammals during the last (Vashon) glaciation. Their unique mammal fauna could be the product of insular evolution, or due to the fact that it is of geographical relicts. Absence of fossil material prohibits a final solution to this problem, but circumstantial evidence suggests that the mammals have evolved their unique characteristics as a result of living in an insular environment. This conclusion is reached after the study of the most common mammals living on the Islands; the deer mice (Peromyscus maniculatus keeni and P. sitkensis prevostensis) and the dusky shrews (Sorex obscurus elassodon and S. o. prevostensis), and after a wide literature survey of mammals found on other islands. The most important evidence favouring the insular evolution theory is the uniformity displayed when the characteristics of insular birds and mammals are compared with relatives living on the nearby mainland. Birds living on islands often possess longer tarsi and culmens; artiodactyls, lagomorphs and carnivores tend to be smaller on islands, while rodents are usually larger, live longer and possess shorter tails. A corollary of the relict hypothesis holds that a large reliot rodent can not survive active competition with the smaller form and is displaced by the latter when they come into contact. This theory could not be substantiated by the present study; on the contrary, the two would likely interbreed. The differences between the insular populations of large Peromysous are greater than one would expect if they owed their similarity to a common origin. Finally, the relict hypothesis would hold that such a characteristic as large size is conservative, whereas evidence indicates that this is not generally true. Reasons are suggested for the characteristics which are commonly found in insular mammals and herein lies the most interesting area for future work. / Science, Faculty of / Zoology, Department of / Graduate
43

O ato político por trás da drag queen: desmontando o essencialismo dos gêneros / The political act behind a Drag Queen: deconstructing the essentialism of genders

Nathalia Sato Campana 29 May 2017 (has links)
O gênero é uma construção social, entretanto, ainda hoje ele é compreendido através de uma visão essencializadora e naturalizadora que se baseia em um aparato de saberes biológicos para reiterar a existência de um alinhamento entre gênero, sexo, prática sexual e desejo. Se enquadrar nesse alinhamento significa estar em consonância com as normas vigentes na nossa sociedade, e todos(as) aqueles(as) que fogem ou provocam nele deslocamentos são tidos(as) como inferiores e indesejáveis, não sendo reconhecidos como seres inteligíveis e estando, então, passíveis de exclusão. O objetivo principal desse estudo constitui em compreender a relação entre a construção parodística das personagens Drag Queens e a construção social dos papéis de gênero, dando prosseguimento à tentativa de desvendar as trajetórias e as compreensões sobre o gênero em pessoas que se encontram fora dos limites impostos pela lógica binária que valida apenas a existência do masculino e feminino, colocando-os como opostos e passíveis de categorização.2 Através do ato estético-político da construção da figura da Drag Queen acredita-se ser possível estar e cruzar a fronteira dos gêneros, tendo uma identidade ambígua ou indefinida e explicitando o caráter artificialmente imposto das identidades fixas, sendo um meio para mapear dispositivos que funcionem em prol da ruptura das ontologias e possibilitem outras formas de vivências que resistam às categorizações socialmente construídas, trazendo potência para a promoção de uma multiplicidade de possibilidades de existência / The term gender is a \"social construction\", however, it\'s still currently understood through an essential and naturalizing vision which is based on an apparatus of biological knowledges to reaffirm the existence of an alignment between gender, sexual orientation, sexual intercourse and desire. Fitting in with such alignment means being in consonance with actual social standards, and all those who avoid or arouse displacements are considered smaller and unwanted, not being recognized as intelligible human beings and, thus, being subject to exclusion. The main goal of this thesis consists on building a relation between the travesty/burlesque construction of the Drag Queens\' characters and the social construction of gender roles, continuing on in the attempt to unravel trajectories and understandings regarding the gender of people who find themselves outside the limits imposed by the binary logic which only validates the existence of male and female genders, placing them as opposites and eligible for categorization3. Through the aesthetic-political act of the construction of the Drag Queen\'s figure it\'s believed it\'s possible to be on and across the genders\' border, possessing an ambiguous or undefined identity and exposing the artificially imposed character of the fixed ones, therefore being a way of mapping devices that work for the rupture of ontologies and enable other ways of living which are able to stand up to socially constructed categorizations, bringing about enough power to promote the plurality of other possible existences
44

On active layer processes and landforms in western Dronning Maud Land, Antarctica

Scott, David Alan January 2015 (has links)
Permafrost is a variable in Antarctic terrestrial ecosystems, and the role it plays in the cryosphere is not well understood. There is much still to be learnt about the thermal state, physical properties, thickness and age of permafrost in Western Dronning Maud Land (WDML). Active layer dynamics and observed change over time have the potential to improve our knowledge of climate change. Understanding the effects of a warming climate on permafrost can also be of benefit to infrastructure, especially in areas with a large amount of frozen ground such as Scandinavia, Canada and Russia. Active layer and permafrost dynamics of WDML, Antarctica, are presented and discussed using data from six study sites, namely the Robertskollen, Vesleskarvet, Flarjuven, Grunehogna, Slettjfell nunataks and the Troll research station in the Jutulsessen area. Ground and ambient air temperature, as well as ground moisture data were collected for each site. An inventory of active layer and permafrost landforms was compiled, as were the frequency of cycles over the zero-degree isotherm, and the depth of the active layer. Furthermore, 3D models, geo-referenced maps and Digital Elevation Models were created of study areas with the use of an Unmanned Aerial Vehicle (UAV). Polygonal features are the most common landscape feature and are common to most of the study sites. Robertskollen has the deepest active layer at over 66cm and Slettfjell the shallowest at 9cm. A maximum recorded air temperature of 8.76°C (10/11/2014) occurred at Troll with the second highest maximum of 6.77°C (22/12/2010) recorded at Vesleskarvet. Robertskollen has the highest observable biological growth and a maximum recorded ground temperature of 22.84°C (10/01/2014). Troll and Valterkulten, registered the second and third highest ground temperatures respectively. The high ground Temperature observed for Robertskollen may be ascribed to it being the lowest altitude site. The highest number of cycles over the zero-degree isotherm was observed at Troll (11.01%), followed by Robertskollen (10.99%). For relatively warm areas, such as Robertskollen it is recommended that two metre borehole loggers are installed in order to capture a detailed understanding of the active layer. The UAV proved to be a beneficial tool for capturing aerial photographs for post fieldwork analysis and 3D modelling.
45

The characterisation of an openwork block deposit, northern buttress, Vesleskarvet, Dronning Maud Land, Antarctica.

Hansen, Christel Dorothee January 2014 (has links)
Investigating openwork block accumulation has the potential to further our understanding of rock weathering, the control of geological structure on landforms, the production of substrates for biological colonisation and the impacts of climate change on landform development and dynamics. Various models for the development of these landforms have been proposed. This includes in situ weathering, frost heave and wedging. Furthermore, it has been suggested that cold-based ice has the potential to preserve these features rather than to obliterate them. Blocky deposits are also frequently used as proxy evidence for interpreting palaeoclimates. The morphology and processes acting on a blockfield located on the Northern Buttress of the Vesleskarvet Nunataks, Dronning Maud Land, Antarctica (2°W, 71°S) were investigated and characterised. Given block dimensions and orientations that closely resembled the parent material and only small differences in aspect related characteristics observed, the blockfield was found to be autochthonous with in situ block production and of a young (Holocene) age. Small differences in rock hardness measurements suggest some form of aspect control on rock weathering. South-facing sides of clasts were found to be the least weathered. In comparison, consistently low rock hardness rebound values for the north-facing aspects suggest that these are the most weathered sides. Additional indicators of weathering, such as flaking and pitting, support analyses conducted for rock hardness rebound values. Solar radiation received, slope gradients and snow cover were found to influence weathering of clasts across the study site. Furthermore, ambient temperatures and wind speed significantly influenced near-surface ground temperatures dynamics. However, the lack of a matrix and paucity of fine material in textural analyses suggest a limited weathering environment. It is suggested that the retreat of the Antarctic ice sheet during the last LGM led to unloading of the surface, causing dilatation and subsequent fracturing of the bedrock along pre-existing joints, leading to in situ clast supply. Subsequent weathering and erosion along other points or lines of weakness then yielded fines and slight edge rounding of clasts.
46

Stream channel morphology : comparison of logged and unlogged watersheds in the Queen Charlotte Islands

Hogan, Daniel Lewis January 1985 (has links)
This study compares the morphology of coastal, gravel-bed streams in two unlogged and two logged Queen Charlotte Islands watersheds. This comparison quantifies the influence of logging and related activities on channel morphology and, consequently, the fresh water physical habitat of salmonids. Further, it provides a basis upon which to determine habitat rehabilitation criteria for disturbed channels. Pools and riffles are detailed because: a) they reflect changes in sediment supply; b) they are important fish habitats, and; c) their general character has been documented in previously published literature allowing application of geomorphological results to habitat evaluation. Longitudinal profiles conducted over relatively long channel segments located within each watershed indicate that channels in watersheds logged to the channel banks by old techniques have reduced pool-to-pool spacings and increased riffle amplitudes and magnitudes. There is an increase in channel stored sediment resulting in proportionally larger riffles and smaller pools. This represents a reduction in available rearing habitat. No significant differences exist in pool and riffle characteristics between unlogged watersheds and those logged by contemporary techniques. In all cases the pool and riffle character differed from most previously published results. Results obtained from detailed study reaches located within each channel segment show that large organic debris is a controlling factor influencing the morphology of these streams. Based upon a comparison of reaches, it is concluded that LOD characteristics are altered in the older logged channels. This includes a shift in the size distribution, with smaller material being more prevalent. Orientation of this material is also altered; more LOD is lying parallel to the flow direction, as opposed to the more common diagonal orientation found in unlogged channels. This shift in orientation is responsible for a reduction in channel width and depth variability, reduced sediment texture, fewer cut banks, smaller pool areas and decreased channel stability. This results in reduced habitat diversity and quality. No morphological differences were detected between unlogged and recently logged reaches. The architecture of unlogged channels can be duplicated to rehabilitate disturbed streams. Pool and riffle sequences should be spaced approximately 2½ channel widths apart and riffle magnitudes should average 0.013 m/m. LOD should play a major role in rehabilitation. Long pieces of debris should be placed either diagonally across the channel to increase depth and width variability and to store sediment or parallel to the flow if width is to be reduced. Diversity can be increased by placing large root wads to produce small scour holes. Only small debris steps, accounting for approximately 10% of the overall change in elevation should be used. This comparative study of channel morphology emphasizes the importance of critically evaluating basin morphometric properties and the role of LOD orientation. Further, it indicates that previous studies reporting average values and neglecting LOD provide insufficient detail to quantify fish habitat. / Arts, Faculty of / Geography, Department of / Graduate
47

Geomorphic and ambient environmental impacts on lichen distribution on two inland Nunataks in western Dronning Maud Land, Antarctica

Dwight, Rosemary Anne January 2015 (has links)
Feedbacks between abiotic variables and community structure in Antarctica are poorly understood. Research is, therefore, required to elucidate the patterns of biodiversity that exist and the factors that influence them, particularly under changing climates. Landscape processes affect environmental heterogeneity, which in turn affect patterns of biodiversity. Two inland Antarctic nunataks, Robertskollen and the Northern Buttress of Vesleskarvet, were selected for investigation to determine the potential impact of selected environmental factors on lichen distribution and abundance, at the intra- and inter-nunatak scales. Lichens were found to prefer rock faces with dips between 1° and 45°, and northern/southern aspects. Lichen colonisation was mostly in microtopographical features that result from rock weathering. The distribution of lichens was found to be regular at the intra- and inter-nunatak scale, whereas lichen abundance was found to be mostly influenced by temperature. On the Northern Buttress, rock hardness displays a similar pattern to lichen abundance, both of which are suggested to be a function of exposure time, which is dependent on deglaciation. The two nunataks serve as excellent laboratories that can potentially be used as proxies for investigating the possible impacts of climate change
48

Debris recharge rates in torrented gullies on the Queen Charlotte Islands

Oden, Marian Elizabeth 11 1900 (has links)
This study is an examination of the rate at which organic debris and clastic sediment accumulate in a gully after it is scoured by a debris torrent. Of particular interest is the effect that a change in land use from old-growth to clear-cut conditions may have on these rates. This change should result in a reduction in the delivery of large organic debris (LOD), which is a major factor in sediment storage in gullies. It is hypothesized that this change in land use, and the subsequent reduction in the LOD supply, should result in a significant difference in debris recharge rates between old-growth and clear-cut gullies. Twenty-nine gullies in both land-treatment groups were sampled on the west coast of the Queen Charlotte Islands. Sampling procedures involved the estimation of the volume of LOD and sediment in storage (normalized by the gully surface area) and the determination of the time elapsed since the last debris torrent. These data were then used to estimate recharge rates(3h1)am’year of LOD, sediment, and total debris. Recharge rates of each material were compared between land-treatment groups using the nonparametric Mann-Whitney test. This test revealed that LOD has been delivered to old-growth gullies at a significantly higher rate relative to clear-cut gullies. There was no significant difference in sediment and total debris recharge rates between gullies in the two groups, but this outcome was partially a result of the small samples and the different debris recharge times in each data set. Graphical representations of the data permitted the identification of possible temporal trends in sediment and debris accumulation, which may be strengthened with larger data sets. Debris recharge rates have several applications. The estimate of sediment volume stored in a gully can be used in the construction of local sediment budgets, as one component of a watershed sediment cascade is quantified. The calculation of debris recharge rates will provide insight into the transfer rate of sediment from hillslopes to low order channels and to the storage capacity of the channels. Finally, debris recharge rates can be used to improve knowledge of the frequency-magnitude characteristics of debris torrents in an area.
49

The many faces of Cleopatra : from propaganda to myth.

Hardman, Naomi Susan. January 2003 (has links)
Few women of antiquity have gripped the public imagination as Cleopatra has. For centuries, she has inspired playwrights, poets, artists and film-makers, with the result that she and Antony are arguably history's most famous lovers. However, I have not yet encountered a study which discusses, in one work, the multiple constructions of Cleopatra across the range of genres in which she has been represented. Certainly, many books and articles are devoted to revealing how Cleopatra has been constructed in one or other specific genre, but it seems as though no attempts have been made to portray, in juxtaposition to one another, the many faces of Cleopatra. This dissertation seeks to do just that. Although I could not possibly include a discussion ofevery genre in which Cleopatra has been constructed, I have chosen six areas for study: ancient Greek biography (using Plutarch's Life ofAntony); the poetry of the Augustan poets: Vergil (the Aeneid), Horace (Ode 1.37) and Propertius (Elegies 3.11); Shakespearean tragedy (Antony and Cleopatra); art (numismatics and ancient sculpture); film (Joseph Mankiewicz's Cleopatra), and, briefly, Africanist historiography. I have chosen these areas because each offers such diverse constructions of Cleopatra that one begins to appreciate how historiography, propaganda and representation have contributed to the shaping ofthe Cleopatra myth, coloured by the ideology ofthe age in which she has been interpreted afresh. Current Africanist appropriations ofCleopatra suggest that historiography is never neutral: race and gender often intersect to create 'historical' identities. / Thesis (M.A.)-University of Natal, Pietermaritzburg, 2003.
50

Debris recharge rates in torrented gullies on the Queen Charlotte Islands

Oden, Marian Elizabeth 11 1900 (has links)
This study is an examination of the rate at which organic debris and clastic sediment accumulate in a gully after it is scoured by a debris torrent. Of particular interest is the effect that a change in land use from old-growth to clear-cut conditions may have on these rates. This change should result in a reduction in the delivery of large organic debris (LOD), which is a major factor in sediment storage in gullies. It is hypothesized that this change in land use, and the subsequent reduction in the LOD supply, should result in a significant difference in debris recharge rates between old-growth and clear-cut gullies. Twenty-nine gullies in both land-treatment groups were sampled on the west coast of the Queen Charlotte Islands. Sampling procedures involved the estimation of the volume of LOD and sediment in storage (normalized by the gully surface area) and the determination of the time elapsed since the last debris torrent. These data were then used to estimate recharge rates(3h1)am’year of LOD, sediment, and total debris. Recharge rates of each material were compared between land-treatment groups using the nonparametric Mann-Whitney test. This test revealed that LOD has been delivered to old-growth gullies at a significantly higher rate relative to clear-cut gullies. There was no significant difference in sediment and total debris recharge rates between gullies in the two groups, but this outcome was partially a result of the small samples and the different debris recharge times in each data set. Graphical representations of the data permitted the identification of possible temporal trends in sediment and debris accumulation, which may be strengthened with larger data sets. Debris recharge rates have several applications. The estimate of sediment volume stored in a gully can be used in the construction of local sediment budgets, as one component of a watershed sediment cascade is quantified. The calculation of debris recharge rates will provide insight into the transfer rate of sediment from hillslopes to low order channels and to the storage capacity of the channels. Finally, debris recharge rates can be used to improve knowledge of the frequency-magnitude characteristics of debris torrents in an area. / Arts, Faculty of / Geography, Department of / Graduate

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