Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 35 for “"gradient analysis"”.
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A gradient analysis of Coleogyne communities in Southern Nevada
… species richness; Detrended correspondence analysis (DECORANA) suggested that elevation and soil depth were significantly associated with the distribution of stand and species groups identified from two-way indicator species analysis (TWINSPAN) in the Spring and Sheep Mountain Ranges. …
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Dinoflagellate biostratigraphy and organic-walled phytoplankton cyst paleoecology of the Demopolis-Ripley transition interval from the Upper Cretaceous Selma Group of Mississippi and Alabama
… Chalk. The application of computer-based gradient analysis programs to a Recent dinoflagellate cyst dataset from the continental shelf of South Africa has shown that gradient analysis of organic-walled phytoplankton cyst assemblages can be useful in the recognition of patterns of marine …
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Community gradients in the Martinsburg formation (Ordovician), southwestern Virginia
… distributed independently along environmental gradients according to their individual requirements. Steep gradients often produce species associations separated by discontinuities; gradual gradients produce broadly-overlapping distributions. Approaching the distribution of species populations …
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The structure of macrofaunal assemblages inhabiting an intertidal sandflat in Tomales Bay, California
… of physical forces, a meaningful community analysis should begin with a description of physical characteristics and faunal distributions over time. The functional importance of certain species in the community should then be investigated by using both field and laboratory experiments. …
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Impact of mine pollution of composition, diversity and structure of plant and ground-dwelling invertebrate communities around Kombat mine tailing dump, Namibia
… traps were used to sample invertebrates. Soil analysis results indicated that concentrations of copper, lead and total sulphur around the dump exceeded CCME guidelines. There were significant differences in plant species richness (F = 6.1, df = 4, p < 0.01), diversity (F = 5.87, df = 4, p < …
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A Vegetative Analysis of Hercules Glades Wilderness
… The Bray-Curtis ordination technique of indirect gradient analysis was applied to the sample plot data in an attempt to determine whether sites located on varying percent slope, exposure, aspect, or stage of successful would group together. In addition, the field data was analyzed to determine …
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Dynamics of forest ecosystem properties and resilience in a temperate woodland undergoing dieback.
… provided an opportunity to measure EPs across a gradient of changing condition. This was carried out through gradient analysis of dieback, based on basal area decline, at the stand scale. Using the results obtained from the gradient analysis: i) the resilience of important woodland EPs was …
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Characterization of Slr1098, a Protein with Similarity to the Bilin Lyase Subunit CpcE from the Cyanobacterium Synechocystis sp. PCC 6803
… exclusion chromatography and sucrose density gradient analysis of complexes formed suggest that Slr1098 strongly interacts with all intermediate forms of phycocyanin and may be an important checkpoint in the biosynthesis and oligomerization of this protein, but that by itself, Slr1098 does not …
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Distribution of Maternal and Fetal Blood Flow within Cotyledons of the Sheep Placenta
… of the uterine—umbilical venous oxygen tension gradient. Analysis of the correlation between samples vs. the distance separating them suggested a weight of roughly 125 mg for hypothetical placental regulatory units.</p>
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Floristic and dynamics of Sand Forest, a subtropical dry forest type in South Africa
… and DCA ordination (Detrended Correspondence Analysis, an indirect gradient analysis) of a wide range of forest samples in north-eastern KwaZulu Natal, South Africa, indicated that Tropical Dry Forest species composition differs substantially from all other forests, and further, that Sand …
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Post-management vegetation change in upland heather moorland, with particular reference to the nutrient status of soils : Lake Vyrnwy Estate, Powys, Mid Wales
… soil samples were taken for chemical analysis.<br/><br/>Dendrochronology was explored as a method for determining the age of Calluna plants in each treatment category from which the efficiency of different methods of removing the Calluna canopy was assessed. Multivariate methods of …
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The Influence of Livestock grazing on Plant Species Diversity and Distribution at Kiranjeranje Ward-Kilwa District
… Kiranjeranje ward was studied using multivariate gradient analysis. Vegetation data were collected in 30 established plots using the stratified random sampling method. For each plot established environmental data on edaphic factors and anthropogenic disturbances were also collected. The plant …
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Constraining the Magneto-Ionic Environment of Galactic Supernova Remnants
… of the sky as possible. One of the most useful analysis tools for doing so is the observation of rotation measures (RMs), a quantity describing the effects of Faraday rotation on polarised radiation that depends on the magnetic field threading the volume of electron gas the radiation travels …
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Maize dwarf mosaic virus: purification, some physical properties, and yield of virus from several corn hybrids
… and differential and sucrose density-gradient centrifugation. Corn tissue was homogenized in 0.1 M sodium citrate plus 0.5% mercaptoethanol. The virus was resuspended after high speed centrifugation in 0.005 M sodium citrate, pH 7.0. Purified virus has an ultraviolet absorption …
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Reservoir characterization of the Hartselle Sandstone in the vicinity of Gorgas Power Plant, using amplitude variation with offset (avo)
… Hartselle Sandstone unit. Using an AVO intercept-gradient analysis along the target horizon (Hartselle Sandstone) across the seismic reflection profiles, the lateral extent of the hydrocarbon resource was mapped up to 1.3 km (0.8 miles) from the test well. The Hartselle Sandstone in the Gorgas …
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The influence of water and light on the physiology and spatial distributions of three shrubs in the Southern Appalachian Mountains
In order to understand vegetational gradients which develop in response to environmental gradients, the physiological capabilities of each species must be examined in relation to the observed environmental gradient. The distributions of three temperate zone shrub species which occupy different …
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Forest ecosystem response to environmental pressures along an urban-to-wildland gradient in southwestern Ohio
… of urbanization gradients, when combined with detailed, quantitative assessments of environmental change along the gradient, have the potential to distinguish the relative influences of multiple anthropogenic environmental disturbances on ecosystems. The purpose of …
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Thermal Gradients in Southwestern United States and the Effect on Bridge Bearing Loads
Thermal gradients became a component of bridge design after soffit cracking in prestressed concrete bridges was attributed to nonlinear temperature distribution through the depth of the bridge. While the effect of thermal gradient on stress distributions has been previously investigated in concrete …
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Vegetation patterns along the Middle Fork of the Flathead River, Glacier National Park, Montana
… point along the transects. TWINSPAN (Hill 1979) analysis was used to identify four distinct cover types and several key indicator species. Direct gradient analysis was used to array cover types and key indicator species along a hydrologic gradient of inundation duration. Plots within the …
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