Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences, 1984. / Microfiche copy available in Archives and Science. / Bibliography: leaf 62. / by Robert Kuklinski. / M.S.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2010. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 22-24). / Sedimentary rocks of all ages abound with geostable lipids of microbial origin, but many biomarkers lack known organismal sources and clear environmental contexts. Here we used Rhodospirillum rubrum, a metabolically versatile, genetically tractable c-Proteobacterium, to explore the diversity of its non-polar terpenoids as a function of growth condition and growth phase. We analyzed the nonpolar fraction of lipids extracted from R. rubrum grown under aerobic, anaerobic, heterotrophic and phototrophic conditions and detected a variety of bicyclic, tricyclic, tetracyclic and pentacyclic triterpenoids, derived from the enzymatic cyclization of squalene and produced in amounts comparable to diploptene. Identified compounds included bicyclic polypodatetraenes, malabaricatriene, euphadiene, adianane, and fernene. Prior to this work, malabaricatriene was an "orphan" biomarker suspected to have a microbial origin, yet it lacked a proven source. We observed similar patterns of polycyclic terpenoids in other hopanoid-producing c-proteobacteria, including Zymomonas mobilis, Rhodopseudomonas palustris, and Rhodomicrobium vannielii. The presence and relative abundance of polycyclic triterpenoids in R. rubrum varied with the growth stage (exponential versus early stationary phase) and growth condition (photoheterotrophic versus photoautotrophic growth). Since R. rubrum's genome contains a single squalene-hopene cyclase gene, the array of triterpenoids produced by it and other c-proteobacteria likely evolves from this enzyme performing low-fidelity cyclization. The observed diversity of sedimentary triterpenoids might therefore result from a select few squalene-hopene cyclase enzymes operating with varying specificity under a range of physiological and environmental conditions, rather than reflecting a great diversity of squalene-hopene cyclases. / by Katherine Harris. / S.M.

Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2007. / Cataloged from PDF version of thesis. / Includes bibliographical references (page 31). / This paper describes the Atlantic Meridional Mode (AMM) and its influence on tropical storm activity in the North Atlantic Basin. The Atlantic Meridional Mode is the oscillating sea- surface temperature (SST) gradient anomaly between the Northern Hemisphere (NH) and Southern Hemisphere (SH) portions of the Tropical Atlantic Ocean (TAO). Synthetic data generated from computer simulations as well as actual reanalysis data from North Atlantic Basin tropical storms was examined. A moderate correlation exists between increased (decreased) North Atlantic tropical storm activity and the high (low) phase of the AMM. The AMM correlates more strongly with the duration and intensity of tropical storms than the frequency. Increased understanding about the AMM and its affects on tropical storm activity will lead to improved forecasting of tropical systems, which affect many human lives each year. / by Nicholas Loyd. / S.B.

Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2009. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 34-35). / The ocean provides a dynamic, constantly changing environment for marine phytoplankton. Understanding the effects of these changes on phytoplankton assemblages is fundamental when trying to anticipate future responses of primary producer's community to long-term environmental changes. In this study, artificial perturbation experiments were successfully performed on natural assemblages of phytoplankton to simulate conditions consistent with ocean acidification and North Pacific Subtropical Gyre (NPSG) upwelling patterns. These experiments demonstrated the feasibility and value of such perturbations in studying phytoplankton responses to environmental forcing. / by Alan D. Foreman. / S.B.

Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, June 2000. / "June 2000." Cataloged from PDF version of thesis. / Includes bibliographical references (page 31). / This investigation uses the variations in composition of lavas and mineralogical evidence to characterize the preeruptive conditions beneath Medicine Lake Volcano (MLV) during the Pleistocene epoch. Prior to this investigation, the Pleistocene lavas of MLV had not been extensively studied because detailed time relations among them were not known. Recent work by Donnelly-Nolan has provided a time framework for relating these lavas, and has afforded us the opportunity to perform this study. Whole rock analyses for major elements, trace elements, and rare earth elements were performed, as well as electron microprobe analyses of individual minerals in the lavas. These analyses indicate that the lavas were formed by the mixing of three components. The first component was formed by fractional crystallization of a high-H20 magma (water content of 3-4 wt%) which was emplaced in the shallow crust, at approximately 1 kbar of pressure and temperatures between 980-1300K. The emplacement and crystallization of the first component supplied the heat necessary to melt the granitic crust under MLV. The crustal melt that resulted formed the second component. The third component was a fresh input from the mantle, whose injection into the shallow crust mixed all three components together. The pre-eruptive environment of these lavas was more oxidizing than those of other MILV lavas, such as the Holocene-aged Glass Mountain rhyolite. / by Heather J. Hooper. / S.B.

Thesis: S.M. in Atmospheric Science, Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2014. / 70 / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 60-65). / This study examines the interaction of clay mineral particles and water vapor to determine the conditions required for cloud droplet formation. Droplet formation conditions are investigated for two common clay minerals, illite and sodium-rich montmorillonite, and an industrially derived sample, Arizona Test Dust. Using wet and dry particle generation coupled to a differential mobility analyzer (DMA) and cloud condensation nuclei counter, the critical activation of the clay mineral particles as cloud condensation nuclei is characterized. Electron microscopy (EM) is used to determine non-sphericity in particle shape. EM is also used to determine particle surface area and account for transmission of multiply charged particles by the DMA. Single particle mass spectrometry and ion chromatography are used to investigate soluble material in wet-generated samples and demonstrate that wet and dry generation yield compositionally different particles. Activation results are analyzed in the context of both K-Köhler theory (K-KT) and Frenkel, Halsey, and Hill (FHH) adsorption activation theory. This study has two main results: (1) K-KT is the suitable framework to describe clay mineral nucleation activity. Apparent differences in K with respect to size arise from an artifact introduced by improper size-selection methodology. For dust particles with mobility sizes larger than ~ 300 nm, i.e. ones that are in an atmospherically relevant size range, both K-KT and FHH theory yield similar critical supersaturations. However, the former requires a single hygroscopicity parameter instead of the two adjustable parameters required by the latter. For dry-generated particles, the size dependence of K is likely an artifact of the shape of the size distribution: there is a sharp drop-off in particle concentration at ~300 nm, and a large fraction of particles classified with a mobility diameter less than -300 nm are actually multiply charged, resulting in a much lower critical supersaturation for droplet activation than expected. For wet-generated particles, deviation from K-KT is likely a result of the dissolution and redistribution of soluble material. (2) Wet-generation is found to be unsuitable for simulating the lofting of fresh dry dust because it changes the size-dependent critical supersaturations by fractionating and re-partitioning soluble material. / by Sarvesh Garimella. / S.M. in Atmospheric Science

Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2003. / Cataloged from PDF version of thesis. Page 36 missing from original thesis. / Includes bibliographical references (page 37). / This research thesis compares the major, most feasible methods of providing the needed amounts of oxygen on the lunar surface for a future human mission. Past studies are combined to provide a comprehensive look at each process and their processing requirements (for example, the mass a processing plant requires, the speed at which the oxygen could be produced, and the cost of setting up such a processing system). There are three methods of in-situ oxygen production that will be researched: hydrothermal reduction, carbothermal reduction, and water/ice electrolysis. Transportation from the Earth is also noted as a basis of comparison. These three methods were chosen because they are the three simplest, most studied methods of regolith reduction to produce oxygen. There have been several studies done on these methods from which I base my research. Pure electrolysis is being studied because of the possibility of water ice at the lunar poles. All three processes are compared and analyzed under various lunar constraints. These constraints limit the feedstock of the system at different locations on the lunar surface. It is found that the water ice concentrations estimated at the north-pole are significantly above that needed to make ice electrolysis the most beneficial method of extraction. However, in mid-latitudes and the south-pole such a definite conclusion is not yet seen. In the south polar regions if the water ice concentration is in the lower half of the bound estimated then ice electrolysis is not the most beneficial, yet if it is in the upper half it will be at least more beneficial than the hydrothermal process, if not the most beneficial. More research must be conducted on the carbothermal system to make definite analysis quantitatively conclusive. / by Joshua Neubert. / S.B.

Thesis (Ph. D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 1988. / Vita. / Includes bibliographical references. / by John P. Jemsek. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences, 1988. / Includes bibliographical references. / by Chia-Yung Chang. / M.S.

Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1991. / Includes bibliographical references (leaves 439-448). / by Lisa Victoria Block. / Sc.D.