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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.
51

Investigating Biosphere-Atmosphere Interactions from Leaf to Atmospheric Boundary Layer Scales

Juang, Jehn-Yih 14 March 2007 (has links)
The interaction between terrestrial ecosystems and the atmosphere continues to be a central research theme within climate, hydrology, and ecology communities. This interest is stimulated by research issues pertinent to both the fundamental laws and the hierarchy of scales. To further explorer such topics over various spatial and temporal domains, in this study, biosphere-atmosphere interactions are studied at two different scales, leaf-to-canopy and canopy-to-atmospheric boundary-layer (ABL) scales, by utilizing both models and long-term measurements collected from the Duke Forest AmeriFlux sites. For the leaf-to-canopy scale, two classical problems motivated by contemporary applications are considered: (1) ‘inverse problem’ – determination of nighttime ecosystem respiration, and (2) forward problem – estimation of two-way interactions between leaves and their microclimate ‘’. An Eulerian inverse approach was developed to separate aboveground respiration from forest floor efflux using mean CO2 concentration and air temperature profiles within the canopy using detailed turbulent transport theories. The forward approach started with the assumption that canopy physiological, drag, and radiative properties are known. The complexity in the turbulent transport model needed for resolving the two-way interactions was then explored. This analysis considered a detailed multi-layer ecophysiological and radiative model embedded in a hierarchy of Eulerian turbulent closure schemes ranging from well-mixed assumption to third order closure schemes with local thermal-stratification within the canopy. For the canopy-to-ABL scale, this study mainly explored problems pertinent to the impact of the ecophysiological controls on the regional environment. First, the possible combinations of water states (soil moisture and atmospheric humidity) that trigger convective rainfall were investigated, and a distinct ‘envelope’ of these combinations emerged from the measurements. Second, an analytical model as a function of atmospheric and ecophysiological properties was proposed to examine how the potential to trigger convective rainfall shifts over different land-covers. The results suggest that pine plantation, whose area is projected to dramatically increase in the Southeastern US (SE), has greater potential to trigger convective rainfall than the other two ecosystems. Finally, the interplay between ecophysiological and radiative attributes on surface temperature, in the context of regional cooling/warming, was investigated for projected land-use changes in the SE region. / Dissertation
52

Architectural variability in the Caddo area of eastern Texas

Schultz, Thomas Clay 07 January 2011 (has links)
This dissertation focuses on the nature of architectural space in the Caddo area of eastern Texas, in the southwestern portion of the Caddo archaeological area. The early European accounts and the archaeological record indicate there was a wide range in size, shape, form, and use of architectural space in the Caddo area. Buildings have a variety of structural attributes and may be found isolated or associated with plazas or earthen mounds. This dissertation is a detailed examination of this architectural diversity. The sites included in this study range from large multi-mound centers that have seen large-scale and long-term research, such as the George C. Davis site, to smaller hamlets and farmsteads. This study includes 265 structures from 31 sites located throughout the Pineywoods, Post Oak Savanna and Blackland Prairie of eastern Texas. This dissertation provides an examination of the structuring of architectural space by Caddo groups living in eastern Texas. Through a detailed examination of documentary, archaeological, and geophysical data, this research examines the nature of the Caddo built environment; how Caddo cultural space was created, maintained, and altered, and how this relates to broader Caddo society. The purpose of this dissertation is to provide descriptions and comparisons of Caddo architecture from eastern Texas to address three interrelated themes: cultural significance of architectural space to the Caddo, physical form of structures and construction attributes, and variation and change. / text
53

Epidemiology of ascochyta blight of chickpea in Australia / by Muhammad Shahid Akhtar Khan.

Khan, Muhammad Shahid Akhtar January 1999 (has links)
Bibliography: leaves 182-217. / xx, 217, [18] leaves, [17] leaves of plates : ill. (chiefly col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This study was conducted to determine the etiology of a blight disease of chickpea in south-eastern Australia and the factors affecting disease development. The disease had previously been identified as phoma blight. Pathogenicity testing revealed two isolates subsequently identified as Asochyta rabiei, the first conclusive identification in the southern hemisphere. Greenhouse screening of chickpea varieties identified types resistant to ascochyta blight. The effects of plant age and environmental conditions on disease development were investigated under controlled conditions in growth rooms. Seedlings were more susceptible than older plants. The optimum conditions for ascochyta blight were 20C and a 48-96 h period of leaf wetness. Through field trials it was found that disease intensity increased over time, especially in cv. Desavic. The means of penetration of the chickpea host was established in histological studies. This study provided advance warning of this disease for the expanding chickpea industry, and has allowed the implementation of appropriate disease management strategies. It is recommended that cv. Desavic should not be grown where ascochyta blight is likely to be a problem. / Thesis (Ph.D.)--University of Adelaide, Dept. of Applied and Molecular Ecology, 1999
54

A study of the hydrochemistry of a limestone area: Buchan, East Gippsland

Ellaway, Edward Mark January 1991 (has links) (PDF)
This thesis reports the results obtained, and conclusions made regarding research into the hydrochemistry of a small impounded karst area in southeastern Australia. Water samples were collected from a variety of sites over a period of approximately six years and include samples that are representative of baseflow (drought conditions) and flood (high flow conditions) the two extremes of the flow regime. Four distinct water types were found to be associated with the karst spring and cave water sites sampled. In terms of physical, chemical and computed parameter values these have been classed as TYPE 1 water (median parameter values similar to those noted for the surface stream sites sampled with catchments of non-carbonate material); TYPE 2 water (catchment predominantly of limestone); TYPE 3 water (catchment predominantly of dolomite); TYPE 4 water (high median chemical concentrations). Spatial variation within the study area is considerable and intrinsic factors such as catchment lithology, the residence time of recharge, aspect and vegetation cover are the major natural controls in determining physical and chemical characteristics.
55

Toward the development of a mentoring program for the pastoral students of Southeastern Bible College, Birmingham, Alabama

Pickell, Bruce Allen. January 2001 (has links)
Thesis (D. Min.)--Dallas Theological Seminary, 2001. / Includes abstract. Includes bibliographical references (leaves 466-476).
56

Toward the development of a mentoring program for the pastoral students of Southeastern Bible College, Birmingham, Alabama

Pickell, Bruce Allen. January 2001 (has links)
Thesis (D. Min.)--Dallas Theological Seminary, 2001. / Abstract. Includes bibliographical references (leaves 466-476).
57

Toward the development of a mentoring program for the pastoral students of Southeastern Bible College, Birmingham, Alabama

Pickell, Bruce Allen. January 2001 (has links)
Thesis (D. Min.)--Dallas Theological Seminary, 2001. / Includes abstract. Includes bibliographical references (leaves 466-476).
58

Toward the development of a mentoring program for the pastoral students of Southeastern Bible College, Birmingham, Alabama

Pickell, Bruce Allen. January 2001 (has links) (PDF)
Thesis (D. Min.)--Dallas Theological Seminary, 2001. / Includes abstract. Includes bibliographical references (leaves 466-476).
59

Ceramic Technology and Cultural Identity in the Fox Lake Sanctuary, Brevard County, Florida

Birnbaum, David 01 December 2014 (has links)
Conventions of Culture-Historical archaeology have persisted in Florida's Indian River Region since the early twentieth century. Traditional ceramic typologies focusing on the superficial stylistic characteristics of pottery have dominated anthropological assessments of Indian River culture during the prehistoric Malabar Period (ca. 1000 BC-AD 1565). Using a practice-oriented approach to analyze technological attributes of St. Johns pottery from Malabar-period assemblages offers an opportunity to examine the communities of practice surrounding craft production as an avenue for elucidating prehistoric cultural identities. This study explores ceramic technology within the Malabar period assemblages of the Fox Lake Sanctuary, and intra-regional and inter-regional site comparisons are quantitatively tested to evaluate variation in technological attributes between assemblages. Statistical results suggest a differentiation between certain technological attributes of St. Johns pottery in Malabar and St. Johns assemblages, notably in the rim thickness and lip morphology of simple form St. Johns Plain vessels.
60

The Southeastern Illinois Prescribed Burn Association: Spearheading Land Management Coalitions in the Midwest

Riechman, Jesse Avery 01 August 2012 (has links)
Fire in Midwestern ecosystems historically has provided many benefits, including promoting forest succession, maintaining wildlife habitat and reducing fuel loads. The Southeastern Illinois Prescribed Burn Association (SIPBA) is the only association of its kind in southern Illinois, designed to reintroduce prescribed fire to landowners in a practical context. The objectives of this research project were: 1) Interview members and crewpersons to collect data on the formation, maintenance, and future of SIPBA, 2) Outline the most common/salient issues driving landowners and stakeholders concerning the use of prescribed fire on their land in southern Illinois, and 3) Provide a conceptual model of the results to serve as a guide for future development of publicly conducted and implemented prescribed burning activities across southern Illinois and, ultimately, the Midwest. This study was implemented by semi-structured interviews of 28 key members of SIPBA. The responses from this population were collected and coded using NVivo 9 qualitative analysis software (NVivo 9 2011). Results indicate that challenges include stubborn remnants of the "Smokey Bear" attitude from the U.S. Forest Service anti-fire campaign, and that liability for an escaped wildfire is a reality for both the individual and for the association. In spite of these and other challenges identified by participants, landowners see SIPBA as a cost-effective solution to their land management needs. The results were interpreted as guidance for future dialogue between landowners and stakeholders and state and federal agencies in implementing prescribed burning programs. Implications include: "fire sells itself." Relatively little effort is needed to attract interest and recruit membership, and the benefits of a prescribed burn are easily evident. Alleviating concerns of the risks associated with fire is a primary objective for the organization, and there is a feeling of "safety in numbers" among membership. Finally, outside funding appears to be the limiting factor for both the capacity and potentially the longevity of the association, meaning that the development of a sustainable funding scheme could allow prescribed burn associations to remain in the Midwest. This case study of SIPBA membership is intended to facilitate cooperation between landowners and local burn associations, and also to serve as a model for the formation of future associations in similar areas of the Midwest.

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