Physical Sciences and Mathematics Commons^™

Enhancing Usability Of The Multi-Channel Analysis Of Surface Wave (Masw) Technique For Subsurface Physical Property Mapping By Incorporating Random-Array Seismic Acquisition, Prasanta Malati Yeluru

Doctoral Dissertations

Subsurface imaging is very critical to exploit subsurface resources, monitor the fluid movement in the reservoir, mapping tunnels etc. As science advances scientists and other researchers are constantly trying to develop new techniques and methods for subsurface imaging that are more effective, efficient, and are more robust under varying field conditions. The main focus of this research is one such effort to improve and increase the usability of the Multi-channel Analysis of Surface Wave method (MASW) method in determining regolith and rock properties by introducing a new type of receiver arrangement to extend its usage in places that are inaccessible …

Species Discrimination, Systematics, And Ontogeny Of Blastoidea, James William Atwood

Doctoral Dissertations

Blastoids are ideal model organisms with which to study evolutionary processes because nearly all of the skeletal elements are shared among all taxa, there have been recent advances in the understanding of blastoid homology, and they are more commonly preserved fully inflated than any other blastozoan. Because of this homology and preservation, blastoids are the perfect candidate for studies involving geometric morphometrics and systematics. But the potential of blastoids to be a model clade has been extremely hampered by the lack of a modern phylogenetics and classification.

The focus of this dissertation is to increase our understanding of blastoid species …

Geologic Investigations In The Central Georgia Inner Piedmont And The Western Flank Of The Carolina Superterrane: Implications Regarding Acadian And Alleghanian Collisional Orogenesis, Fault Reactivation, And The Mesozoic Breakup Of Pangea, Matthew Tiesher Huebner

Doctoral Dissertations

Detailed geologic mapping, U-Pb geochronology, igneous petrology and whole-rock geochemical analysis, and structural analysis of the Inner Piedmont and Carolina superterrane were conducted to better define the tectonic history of the southern Appalachian orogen; results yield implications for Acadian/Neoacadian and Alleghanian collisional events and Mesozoic breakup of Pangea. Detailed geologic mapping was focused in the Inner Piedmont at the northeastern end of the Pine Mountain window to investigate an aeromagnetic anomaly that was hypothesized to represent the southwestern continuation of the Brindle Creek fault, which separates the Inner Piedmont terranes (Tugaloo and Cat Square). Evidence supports this hypothesis, while contrasting …

Scale-Dependent Heterogeneity In Fracture Data Sets And Grayscale Images, Ankur Roy

Doctoral Dissertations

Lacunarity is a technique developed for multiscale analysis of spatial data and can quantify scale-dependent heterogeneity in a dataset. The present research is based on characterizing fracture data of various types by invoking lacunarity as a concept that can not only be applied to both fractal and non-fractal binary data but can also be extended to analyzing non-binary data sets comprising a spectrum of values between 0 and 1. Lacunarity has been variously modified in characterizing fracture data from maps and scanlines in tackling five different problems. In Chapter 2, it is shown that normalized lacunarity curves can differentiate between …

Stratigraphic And Geochemical Investigation Of The Mesoproterozoic Atar And El Mreiti Groups, Mauritania: Insights Into Carbon Cycling And Ocean Redox Stratification In A Low Oxygen World, Geoffrey J. Gilleaudeau

Doctoral Dissertations

The protracted oxygenation of Earth’s surface environments played a critical role in biospheric evolution during the Proterozoic eon. Initial oxygenation began ~2.3 Ga during the Great Oxidation Event, yet Earth’s oceans did not become fully oxygenated until at least the end of the Neoproterozoic—coincident with the first appearance of metazoans in the fossil record. Patterns of environmental change and evolutionary innovation are more complex and less certain, however, in the prolonged period between these two oxygenation thresholds. The late Mesoproterozoic (1.3 to 1.0 Ga) was marked by increasing biospheric oxygen—evidenced by increased carbon isotopic variability and an increase in marine …

Genetic Analysis Of Bacterial Gene Variations In Sulfidic Springs And The Influence On Geochemistry, Brendan Joseph Headd

Doctoral Dissertations

Culture-independent methods have revolutionized environmental microbiology and geomicrobiology studies and next-generation sequencing and metagenomics techniques continue to reveal the vast genetic diversity of microorganisms. But, these approaches provide comparatively little quantitative information about the roles that naturally occurring microbial gene variations play in local biogeochemical cycling. The goal of this study was to identify how the physical distribution and genetic diversity of microbial genes within a habitat impact environmental geochemistry by examining the biogeography of 16S rRNA genes and bacterial sulfur oxidation (Sox) genes in terrestrial sulfidic springs. 16S rRNA gene pyrosequences were obtained from microbial mats inhabiting eight sulfidic …

Evaluating Predictability In The Community Earth System Model In Response To The Eruption Of Mount Pinatubo, Abigail Laurel Gaddis

Doctoral Dissertations

A central goal of climate research is to determine the perceptible effects of climate change on humans; in other words, the regional and decadal scale effects of carbon dioxide forcing. Identifying the most pronounced and long-lasting responses of climate variables to forcing is important for decadal prediction since forcing terms are a source of predictability on those time scales. Powerful volcanic eruptions provide a transient forcing on the climate system, creating a test bed for climate models. In this study, the Mount Pinatubo eruption is simulated in the Community Earth System Model, CESM1.0, for three model configurations: fully coupled T85 …

Sociobiophysicality, Cold War, And Critical Theory: Human-Ecological Transformation And Contemporary Ecological Subjectivity, Alexander Stoner

Doctoral Dissertations

The United States is an important global player in resource depletion, energy use, waste production, and other indicators that contribute to economic threats to humanity’s ecological future. Critical theory provides conceptual tools that are uniquely well-suited to more fully comprehend the links between economic progress and ecological deterioration. In key regards, the present situation is the continuation as well as amplification of political-economic, social and cultural features that took hold during the Cold War, and which demand rigorous sociological focus, scrutiny and analysis. To date, however, sociology has barely begun to assess the consequences that resulted from the Cold War …

Mechanisms Of Nutrient Limitation And Nutrient Acquisition In Managed And Unmanaged Forest Ecosystems, Matthew A. Vadeboncoeur

Doctoral Dissertations

Understanding the interactions between global change, human and natural disturbances, and other factors on biogeochemical processes in forests is necessary to ensure the sustainability of forest management. Here I report the results of several investigations into nutrient acquisition processes in the forests of New Hampshire. I begin with a meta-analysis of fertilization studies showing that phosphorus (P) and calcium (Ca) as well as nitrogen (N) may limit primary production in deciduous forests of the region. Because these limiting nutrients are all removed from the ecosystem when trees are harvested, I compared nutrient budgets under a range of harvesting scenarios with …

Martian Dune Fields: Aeolian Activity, Morphology, Sediment Pathways, And Provenance, Matthew Chojnacki

Doctoral Dissertations

Wind has likely been the dominant geologic agent for most of Mars’ history. The wide-spread nature of sand dunes there shows that near-surface winds have commonly interacted with plentiful mobile sediments. Early studies of these dunes suggested minimal activity, dominantly unidirectional simple dune morphologies, and little variations in basaltic sand compositions. This dissertation examines martian sand dunes and aeolian systems, in terms of their activity, morphologies, thermophysical properties, sand compositions, geologic contexts, and source-lithologies using new higher-resolution orbital data. Although previous evidence for contemporary dune activity has been limited, results presented in Chapter II show substantial activity in Endeavour Crater, …

Quantitative Integration Of Multiple Near-Surface Geophysical Techniques For Improved Subsurface Imaging And Reducing Uncertainty In Discrete Anomaly Detection, Megan Estelle Carr

Doctoral Dissertations

Currently there is no systematic quantitative methodology in place for the integration of two or more coincident data sets collected using near-surface geophysical techniques. As the need for this type of methodology increases—particularly in the fields of archaeological prospecting, UXO detection, landmine detection, environmental site characterization/remediation monitoring, and forensics—a detailed and refined approach is necessary. The objective of this dissertation is to investigate quantitative techniques for integrating multi-tool near-surface geophysical data to improve subsurface imaging and reduce uncertainty in discrete anomaly detection. This objective is fulfilled by: (1) correlating multi-tool geophysical data with existing well-characterized “targets”; (2) developing methods for …

Palynology Of Acid-Saline Lakes Of Western Australiabiostratigraphy And Paleoenvironmental Reconstruction, Carlos A. Sanchez Botero

Doctoral Dissertations

"Lakes are excellent repositories of fossils and sedimentary features that provide clues to past climatic and geologic events. Sediments from four cores drilled in Lake Aerodrome (LA1-09, LA2-09) and Lake Brown (LB1-09, LB2-09), two of the hundreds of ephemeral lakes in southern Western Australia, were analyzed for their palynological contents to understand the geologic and climatic evolution of the depositional basin. Palynofacies assemblages defined by statistical analyses of dispersed organic matter suggested differences in the depositional conditions and probable correlations between Lake Aerodrome cores. Detailed identifications and quantification of organic-walled microfossils yielded two palynomorph assemblages that reflect a climatic turnover: …

Geochemical And Isotopic Characterization Of Lead In Fugitive Dust From Unsurfaced Roads In Missouri, Emitt C. Witt

Doctoral Dissertations

"Eighteen unsurfaced roadways in Missouri's rural Ozark region were sampled to characterize the differences in trace element and isotopic chemistry to determine if there is a human health concern with inhaling and/or ingestion of fugitive dust generated by a moving vehicle. Road reaches were selected to represent those in similar rural areas with and without the presence of mining activity--13 roads were selected in the Viburnum Trend (VT) resource mining area and five were located to the southwest of the mining areas. Samples were collected using a novel cyclonic fugitive dust sampler (patent pending) that collects a composite sample from …