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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.
21

Soil-based analysis methods to aid the detection of cropmarks over buried features

Pring, Lleyton James January 2016 (has links)
Without contention, aerial surveying has been one of the most fundamental and effective tools in archaeological research. The mapping of cropmarks using aerial surveys, which appear over buries features, has revealed tens of thousands of new archaeological sites in Britain in the last few years. Cropmarks have most commonly been found when the weather is dry and in areas where soils drain quickly, causing crops to come under stress due to a lack of water. This knowledge informs archaeologists in the planning of surveys. However, targeting these areas in dry conditions introduces bias into the dataset and the rate of new discoveries is slowing. This research assesses the underlying geotechnical characteristics of soils within and adjacent to buried ditches at four field trial sites, to increase the understanding of why these cropmarks form and the conditions in which they appear. Analysis methods using existing archaeological and geotechnical data have been proposed to increase the knowledge of the conditions in which cropmarks form. The methods have been tested and the results showed that cropmarks formed in areas of clay-dominated soils in wet conditions, and cropmarks were recorded across a much wider range of soil-water conditions than was expected from current knowledge.
22

Quantifying the dynamic response of permafrost and slope stability to a changing climate

Mithan, Huw January 2018 (has links)
The Arctic contains a wealth of landforms that are governed by the diurnal and seasonal response of permafrost to climatic and topographic forcings. Of key importance to the process rates of many periglacial landforms is the dynamic behaviour of the active layer, which regulates the transfer of heat and moisture between the atmosphere and permafrost. The strong dependence of periglacial process rates on active layer dynamics makes this geomorphic system particularly sensitive to future increases in Arctic temperatures and precipitation. These increases will continue to degrade permafrost, affecting the distribution and rates of periglacial processes. I develop a landform classification model on Svalbard that reveals solifluction and scree to be the most dominant hillslope processes acting on this landscape, with sediment fluxes greatest in solifluction. A combination of landslide mapping, solifluction modelling and slope stability analysis in Alaska reveals that landslides are coincident with convergent topography on soliflucting hillslopes that have concentrated ground ice at depth. Convergent topography allows for higher moisture availability that feeds the growth, concentration, and development of a large network of ice lenses at the permafrost/active layer boundary. The excess pore pressures generated upon thaw reduces the shear strength of soil at the base of the active layer, causing it to slide downslope along a planar slip surface on top of the unthawed permafrost. Due to a warming Arctic, permafrost is expected to continue thawing, creating an ever more dynamic and deeper active layer. Consequently, the relative regional extent of periglacial landforms in mountainous Arctic environments is expected to change, with Arctic hillslopes becoming more unstable during extreme summer thawing. This will pose a greater hazard to Arctic infrastructure and act as a major force for environmental and geomorphological change.
23

Glasgow's spatial arrangement of deprivation over time : methods to measure it and meanings for health

Stewart, Joanna L. January 2016 (has links)
Background: Socio-economic deprivation is a key driver of population health. High levels of socio-economic deprivation have long been offered as the explanation for exceptionally high levels of mortality in Glasgow, Scotland. A number of recent studies have, however, suggested that this explanation is partial. Comparisons with Liverpool and Manchester suggest that mortality rates have been higher in Glasgow since the 1970s despite very similar levels of deprivation in these three cities. It has, therefore, been argued that there is an “excess” of mortality in Glasgow; that is, mortality rates are higher than would be expected given the city’s age, gender, and deprivation profile. A profusion of possible explanations for this excess has been proffered. One hypothesis is that the spatial arrangement of deprivation might be a contributing factor. Particular spatial configurations of deprivation have been associated with negative health impacts. It has been suggested that Glasgow experienced a distinct, and more harmful, development of spatial patterning of deprivation. Measuring the development of spatial arrangements of deprivation over time is technically challenging however. Therefore, this study brought together a number of techniques to compare the development of the spatial arrangement of deprivation in Glasgow, Liverpool and Manchester between 1971 and 2011. It then considered the plausibility of the spatial arrangement of deprivation as a contributing factor to Glasgow’s high levels of mortality. Methods: A literature review was undertaken to inform understandings of relationships between the spatial arrangement of deprivation and health outcomes. A substantial element of this study involved developing a methodology to facilitate temporal and inter-city comparisons of the spatial arrangement of deprivation. Key contributions of this study were the application of techniques to render and quantify whole-landscape perspectives on the development of spatial patterns of household deprivation, over time. This was achieved by using surface mapping techniques to map information relating to deprivation from the UK census, and then analysing these maps with spatial metrics. Results: There is agreement in the literature that the spatial arrangement of deprivation can influence health outcomes, but mechanisms and expected impacts are not clear. The temporal development of Glasgow’s spatial arrangement of deprivation exhibited both similarities and differences with Liverpool and Manchester. Glasgow often had a larger proportion of its landscape occupied with areas of deprivation, particularly in 1971 and 1981. Patch density and mean patch size (spatial metrics which provide an indication of fragmentation), however, were not found to have developed differently in Glasgow. Conclusion: The spatial extent of deprivation developed differently in Glasgow relative to Liverpool and Manchester as the results indicated that deprivation was substantially more spatially prevalent in Glasgow, this was particularly pronounced in 1971 and 1981. This implies that exposure of more affluent and deprived people to each other has been greater in Glasgow. Given that proximal inequality has been related to poor health outcomes, it would appear plausible that this may have adversely affected Glasgow’s mortality rates. If this is the case, however, it is unlikely that this will account for a substantial proportion of Glasgow’s excess mortality. Further research into Glasgow’s excess mortality is, therefore, required.

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