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 14 of 14 for “"impact processes"”.
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The Early Evolution of Terrestrial Planets: Impact Simulations and Planetary Chemistry
Large impacts early in the lifetime of a terrestrial planet can transform its surface environment and interior composition, with the potential to forever change the evolutionary pathways available to that world. The chemically reduced metallic iron cores of these large impactors are key to such …
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Differentiation in impact melt sheets as a mechanism to produce evolved magmas on Mars
… Martian crust. However, information about how impact melting has altered Mars’ crustal petrology is limited. Evidence from some of the largest impact structures on Earth, such as Sudbury and Manicouagan, suggests that some impact melt sheets experience chemical differentiation. If these …
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Structure of the Chesapeake Bay Impact Crater from Wide-Angle Seismic Waveform Tomography
The Chesapeake Bay impact structure is one of the largest and most well preserved impact structures on Earth. It has a unique morphology composed of an inner crater penetrating crystalline basement surrounded by a wider crater in the overlying sediments. In 2004, the U.S. Geological Survey …
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Hypervelocity impacts and the evolution of planetary surfaces and interiors
The thesis consists of five studies relating impact processes to the evolution of planetary interiors as well as impact structures on planetary surfaces. Chapter 2 is concerned with developing methods for estimating the amount of heat deposited deep in terrestrial mantles by large impacts. Chapter …
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HOME : collecting narratives, promoting dialogue, and guiding change
… is imperative to see urban planning's historical impact on the communities vulnerable populations, particularly communities of color, have fought to call home. Understanding the sense of home is crucial to begin humanizing the lived experiences city-dwellers have in places. These places move …
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Planetary Materials Science and Astrobiology
Planetary materials contain signatures of diverse processes in their mineralogy, chemistry, textures and assemblages. The record contained in planetary materials reflects the complex and commonly overprinting relationships between many processes. Discerning what mechanisms have operated to produce …
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The geophysical evolution of impact basins and volcanic structures on Mercury and the Moon
… terrestrial bodies are dominated by two major processes: meteorite bombardment and volcanism. The forms that the resulting impact craters and volcanic structures take can tell us a great deal about the ways in which these processes occur and about the environment of the host body at the time of …
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Late accretion to the early Earth and rocky exoplanets
… -- with the nascent planet. It is thought these impacts, delivering vast sums of energy, may have transformed surface environments -- melting Earth's primitive crust, and sterilizing the surface of putative life. In contrast, it is also thought these impacts may have assumed a central role in the …
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Fluids in Planetary Systems
… shaping planetary bodies. Fluid properties and processes were investigated under a range of planetary conditions through (1) experimental simulations of impact events and petrographic analysis of terrestrial impactites to determine the effects of shock metamorphism on fluid inclusion properties; …
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Observing microbial processes at the microscale with in situ technology
… with numerous biological and physical processes giving rise to resource hotspots where nutrient concentrations exceed background levels by orders of magnitude. While the impact of this microscale heterogeneity has been investigated in the laboratory with microbial isolates and …
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The discovery of baddeleyite (ZrO2) and chrome spinel in the basal Rooiberg Group of the 2.057 Ga Bushveld Complex, South Africa: Implications for the impact and igneous scenarios for the petrogenesis of the Rooiberg Group.
… Suite and 2) crustal melting initiated by an impact of one or more bolides. Although evidence for shock metamorphism, key to verifying an impact origin, has not been found, it has been proposed that unique quench textures in the Basal Rhyolite formed during quenching from impact-induced …
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Contribution of the First Electronically Excited State of Molecular Nitrogen to Thermospheric Nitric Oxide
… model. The method is to scale the photoelectron impact ionization rate of molecular nitrogen by a Gaussian centered near 100 km. Large uncertainties remain in the temperature dependence and branching ratios of many reactions important to NO production and loss. Similarly large uncertainties are …
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Cellular Uptake of Neutrohpil Elastase Links Inflammation to Adaptive Immunity
… that uptake of NE by tumor cells could impact processes regulating tumorigenensis other than activation of the PI3K pathway.</p> <p>Neutrophil elastase has been identified in breast cancer specimens where high levels of NE have prognostic significance. These studies have assessed NE …
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Reactive solids under shock compression
… using PDV to determine the range of impact velocities and shock wave durations that aluminum or copper flyers can impart into materials. Ultrafast stroboscopic imaging was used to determine the planarity and size of flyer plates at the time of material impact. By combining …