Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1984. / Includes bibliographical references (leaves 211-215).

Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references. Also available on the World Wide Web.

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The reconstruction of marine-based paleo ice sheet dynamics can reveal long-term ice sheet activity, and in turn provide constraints on the response of modern marine ice sheets (e.g. the West Antarctica Ice Sheet) to climate change. The marine-terminating Hebrides Ice Stream (HIS) flowed across the western Scottish shelf during the last glacial maximum (3024 ka) and drained a large portion of the northern sector of the British Irish-Ice Sheet (BIIS), affecting its stability. This thesis aims to examine how the HIS evolved and interacted with the changing climate and the underlying landscape after 27 ka. The work is subdivided into: a) an investigation of modern high-resolution bathymetry data coupled with seismic data with the aim of reconstructing deglacial dynamics; b) the analysis of Pb isotopic composition in sediment cores on the shelf in order to locate glacial sediment provenance; c) a study of Hebrides shelf core sedimentology and microfaunal assemblage to reconstruct Lateglacial paleoenvironmental changes. A three-stage deglacial pattern, where topography played a critical role, is defined: i) ice stream margin retreat punctuated by standstills, ii) topography-controlled fjordic retreat, with evolution from a coherent ice-sheet to separate fjord tidewater glaciers, and iii) a stabilisation at the transition from tidewater to land-based ice margins. Between 21 and 15 ka, fine-grained sediments transported by meltwater plumes were the product of erosion of Neoproterozoic basement, while the coarse-grained sediments were instead sourced from island igneous rocks. These results indicate prevailing sediment input from NW Scotland. Lateglacial sediment deposition was strongly influenced by shelf currents and shows wide variation. Therefore, the seismic and sedimentological interpretations need to be considered only on a local scale. Glacimarine sandy deposits in the Muck Deep region support a prolonged glacial occupancy until the latest stages of GS-1 (12.8-11.7 ka), and are at odds with recent studies indicating earlier glacial retreat. The thesis demonstrates the complex interactions between BIIS evolution, subglacial landscape and ocean dynamics. The outcome of this research can be useful to inform future numerical reconstructions.

Soil organic carbon (SOC) is important both for its influence on agricultural productivity and for its role in the carbon cycle. The distribution of SOC is highly variable at the field scale both horizontally and vertically; a portion of SOC's variability can be attributed to differences in vegetative cover and to slope position. This study characterized and compared SOC concentration to a depth of 2 meters across 6 loess-veneered watersheds in the central United States. Data were collected as part of the Shawnee Hills Loess Catenas project, a collaboration between the U.S. Department of Agriculture (USDA) Natural Resources Conservation Service, USDA Forest Service, Purdue University, University of Kentucky, Southern Illinois University at Carbondale, and Illinois State Geological Survey, among others. The study consists of pairs of sites, one under forest cover and one grass cover, located in southern Illinois, southern Indiana, and western Kentucky. Bulk density and SOC data were calculated from genetic horizon samples taken from soil pits laid out as transects along slopes at each site. SOC concentrations were significantly higher under forest cover. Footslopes and toeslopes had significantly higher SOC densities than summits, shoulders, and backslopes. A three-part exponential decay model was the best fit for the relationship between SOC density and depth from the surface. The comparisons and models may be used to more accurately predict SOC concentration and carbon pool size on similar loess-veneered landscapes in the central United States.

This investigation assessed the utility of a selection-based instructional program in teaching relations between driving behavior and driving stimuli in addition to the emergence of topography-based responding. A selection-based instructional program was delivered to three individuals with intellectual disabilities and/or learning disabilities in order to teach participants relations of sameness between automobile operation stimuli and driving behaviors. Participants were directly taught relations between video models of vehicle operation, road sign outlines, and textual stimuli of road signs using a selection-based instructional protocol delivered via a computer program. Following mastery of the selection-based instruction the emergence of selection-based responding on symmetrical and transitive posttest probes at the mastery level was observed for all 3 participants. Furthermore, movement on posttest generalization vehicle simulator probe was observed for one participant.

Isostasy, flexure and dynamic processes all influence the shape of the Earth’s surface. While the first two processes are well understood, dynamic topography remains controversial. On the continents, dynamic uplift is often expressed by positive long-wavelength gravity anomalies, radial drainage patterns, and slow seismic velocity anomalies within the upper mantle. Volcanic activity and elevated heat flow are also often observed. The aim of this study is to investigate the link between geochemical compositions of intracontinental magmatism and geophysical, geomorphological and geodetic observations of dynamic uplift. Three volcanic regions are considered in detail: western North America, northeast Brazil and Madagascar. The combined database includes 348 new whole-rock geochemical analyses. Rare earth element concentrations of mafic, asthenospheric-derived volcanic samples are exploited to calculate the depth and temperature of melt generation by inverse modelling. A sensitivity test of this modelling scheme is carried out. Lithospheric thickness and mantle temperature are independently determined from shear wave velocity models. Beneath western North America, a negative correlation between shear wave velocities at depths of 70–150 km and degree of melting is observed. Temperatures obtained from igneous compositions and from shear wave velocity profiles beneath volcanic fields closely agree. Melts are produced within, or close to, the spinel-garnet transition zone at depths shallower than $\sim$70 km, yielding mantle potential temperatures of up to 1380$^{\circ}$C. Calculated uplift and heat flow based upon these results match observed surface elevation and heat flow measurements. In northeast Brazil, Jurassic, Cretaceous and Cenozoic phases of mafic igneous activity are recognised. Jurassic magmatic activity probably resulted from spinel-field melting at potential temperatures of $\sim$1380$^{\circ}$C. This episode is associated with regional magmatism during break-up of the Central Atlantic Ocean. Cretaceous compositions record melting at potential temperatures of 1330–70$^{\circ}$C at similar depths. This activity is linked to extension at the time of break-up of the equatorial and South Atlantic Ocean. Cenozoic volcanism comprises low-degree melts within the spinel-garnet transition zone at ambient potential temperature. Shear wave velocity models support these results. Cenozoic volcanism in Madagascar is predominantly alkaline and records small-degree melting with minor temperature anomalies within the spinel-garnet transition zone. Rare tholeiitic basalts record temperatures up to 1360$^{\circ}$C. Analysis of global and regional shear wave velocity models closely matches these results. The principal control on continental magmatism appears to be temperature anomalies within the upper mantle beneath thin lithosphere. Highest mantle potential temperatures correlate with largest dynamic uplift. Mantle potential temperatures $ < $1350$^{\circ}$C are matched with minimal or negative dynamic topography.

Orientador: Reginaldo José Donatelli / Banca: Fátima do Rosário N. Knoll / Banca: Carolina Demetrio Ferreira / Resumo: Este estudo teve como objetivo analisar as comunidades de aves em duas variáveis topográficas de 480m Porção Norte (PN) e 520m Porção Sul (PS) na Estação Ecológicas dos Caetetus, verificando assim, suas relações ecológicas quanto a composição de espécies, abundância, estrutura trófica e estratificação da avifauna, bem como testar se há variações na detecção de espécies e indivíduos em períodos diferentes em dois períodos do dia (manhã e tarde) e do ano, sendo o período chuvoso (dezembro de 2007 a abril 2008) e seco (maio a setembro de 2008). O estudo ocorreu entre os meses de dezembro de 2007 a janeiro de 2008, utilizou-se o método de Ponto de Escuta. O levantamento quantitativo registrou 125 espécies para PN e 156 espécies para PS. O Índice Pontual de abundância variou de 0,008 (1 contato) a 0,87 (210 contatos) na PN e de 0,004 (1 contato) a 0,91 (219 contatos) na PS. A diversidade para PN foi de = 3,76 e para PS H' = 2,68. A comunidade de aves mostrou o mesmo padrão encontrado em outros fragmentos florestais de mata estacional semidecidual. Os insetívoros foram a categoria mais representativa, sendo a família Tyrannidae a que mais se destacou nas duas porções. As diferenças encontradas entre as duas porções foram resultantes das características da vegetação que garantiram boa parte das espécies exclusivas na PS, o que indica a forte influência da vegetação nas aves. O estudo da influencia do dia, mostrou os dados apóiam a idéia de maior atividade das aves se dá durante a manhã, sendo este período responsável pelo registro significativo de mais espécies e indivíduos. Já a analise da influência do regime de chuvas na EECa não influenciou a distribuição das aves / Abstract: This study it had as objective to analyze the communities of birds in two topographical variable of 480m Porção Norte (PN) and 520m Porção Sul (PS) in the ecological Station Ecological of the Caetetus, thus verifying, its relations how much the species composition, abundance, structures of guildas and stratification of avifauna, as well as testing if it has variations in the species detention and individuals in different periods in two periods of the day (morning and late) and of the year, being the rainy period (December of 2007 April 2008) and dry (May the September of 2008). The study the January of 2008 occurred enters the months of December of 2007, used the method of Point of Listening. The quantitative survey registered 125 species for PN and 156 species for PS. The Prompt Index of abundance varied of 0,008 (1 contact) the 0,87 (210 contacts) in the PN and of 0,004 (1 contact) the 0.91 (219 contacts) in the PS. The diversity for PN was of = 3,76 and for PS H' = 2,68. The community of birds the same showed standard found in other forest fragmentos of semidecidual estacional bush. The insetívoros had been the category most representative, being the Tyrannidae family the one that more was distinguished in the two portions. The differences found between the two portions had been resultant of the characteristics of the vegetation that had guaranteed good part of the exclusive species in the PS, what it indicates the strong influence of the vegetation in the birds. The study of it influences of the day, it showed the data support the idea of bigger activity of the birds if of the one during the morning, being this responsible period for the significant register of more species and individuals. Already it analyzes it of the influence of the rain regimen in the EECa did not influence the distribution of the birds / Mestre

The bathymetry, magnetic anomalies, gravity anomalies and sediment layer is presented to support a young Western Mediterranean no older than 25 million years and an Eastern Mediterranean as old as 200 million years. A buried salt layer is detected in seismic reflection profiles lying below a sediment cover whose base is 4 to 5 million years in age. The seafloor in the eastern Mediterranean is being actively deformed by compressional folding and thrusting beneath the Mediterranean Ridge. The Western Mediterranean opened by rifting and is floored by oceanic crust.

The purpose of this thesis was to study the influence of manufacturing variations on gear performance. The manufacturing variations inherent in different manufacturing methods were studied to include the effect of real surfaces. Real surfaces have surface irregularities at least on some scale, which can significantly influence how loads are transmitted at the gear contact. To some extent, the lubricant design can help to prevent contact that could lead to tooth failures by forming a protective surface boundary layer. An experimental study was used to consider the compositions of these layers with a surface analysis method. In Paper A a robust design approach was used to find out to what extent the current standard for calculation of surface durability treats manufacturing variations and the choice of lubricant. The results show that the simplest calculation method used is not enough to predict the effect of these on surface durability. Additionally, the standard quality levels are poorly incorporated in the standard calculating procedures for surface durability, and the quality of the gear tooth is restricted to include only a few parameters. In Paper B a pin-on-disc machine was used to evaluate the tribofilm formation by the additives and the corresponding wear occurring in the boundary lubrication regime in environmentally adapted lubricants. Studies of the additive and base fluid interaction were carried out using glow discharge-optical emission spectroscopy. It was found that the chemically reacted surface boundary layers played an important role in terms of wear. More specifically, the oxide layer thickness had significant influence on wear. The findings also demonstrate the complexity of lubrication design formulations coupled to these layers. For example, it was found that the pre-existing surface boundary layer (before any lubricant had been added) played an important role in allowing the lubricant to react properly with the surfaces. The aim of Paper C was to contribute to the knowledge of how different surface topographies, tied to manufacturing methods, influence the early life contact conditions in gears. Topographical measurements of differently manufactured tooth flanks were used as data input to a contact analysis program. The variation in surface topography inherent in the manufacturing method was found to have a strong influence on the contact area ratio.