Specializing pedestrian maps to address the needs of people using wheelchairs: a case study in community-sustainable information systems

Gemstone Team FASTR (Finding Alternative Specialized Travel Routes)

Geochemistry of crustal formation and evolution

Terrestrial planets produce crusts as they differentiate. The Earth’s bi-modal crust, with a high-standing granitic continental crust and a low-standing basaltic oceanic crust, is unique in our solar system and links the evolution of the interior and exterior of this planet. Here I present geochemical observations to constrain processes accompanying crustal formation and evolution. My approach includes geochemical analyses, quantitative modeling, and experimental studies. The Archean crustal evolution project represents my perspective on when Earth’s continental crust began forming. In this project, I utilized critical element ratios in sedimentary records to track the evolution of the MgO content in the upper continental crust as a function time. The early Archean subaerial crust had >11 wt. % MgO, whereas by the end of Archean its composition had evolved to about 4 wt. % MgO, suggesting a transition of the upper crust from a basalt-like to a more granite-like bulk composition. Driving this fundamental change of the upper crustal composition is the widespread operation of subduction processes, suggesting the onset of global plate tectonics at ~ 3 Ga (Abstract figure). Three of the chapters in this dissertation leverage the use of Eu anomalies to track the recycling of crustal materials back into the mantle, where Eu anomaly is a sensitive measure of the element’s behavior relative to neighboring lanthanoids (Sm and Gd) during crustal differentiation. My compilation of Sm-Eu-Gd data for the continental crust shows that the average crust has a net negative Eu anomaly. This result requires recycling of Eu-enriched lower continental crust to the mantle. Mass balance calculations require that about three times the mass of the modern continental crust was returned into the mantle over Earth history, possibly via density-driven recycling. High precision measurements of Eu/Eu* in selected primitive glasses of mid-ocean ridge basalt (MORB) from global MORs, combined with numerical modeling, suggests that the recycled lower crustal materials are not found within the MORB source and may have at least partially sank into the lower mantle where they can be sampled by hot spot volcanoes. The Lesser Antilles Li isotope project provides insights into the Li systematics of this young island arc, a representative section of proto-continental crust. Martinique Island lavas, to my knowledge, represent the only clear case in which crustal Li is recycled back into their mantle source, as documented by the isotopically light Li isotopes in Lesser Antilles sediments that feed into the fore arc subduction trench. By corollary, the mantle-like Li signal in global arc lavas is likely the result of broadly similar Li isotopic compositions between the upper mantle and bulk subducting sediments in most arcs. My PhD project on Li diffusion mechanism in zircon is being carried out in extensive collaboration with multiple institutes and employs analytical, experimental and modeling studies. This ongoing project, finds that REE and Y play an important role in controlling Li diffusion in natural zircons, with Li partially coupling to REE and Y to maintain charge balance. Access to state-of-art instrumentation presented critical opportunities to identify the mechanisms that cause elemental fractionation during laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis. My work here elucidates the elemental fractionation associated with plasma plume condensation during laser ablation and particle-ion conversion in the ICP.

Comparative transcriptome profiling of human foreskin fibroblasts infected with the Sylvio and Y strains of Trypanosoma cruzi

Trypanosoma cruzi, the causative agent of Chagas Disease, is phylogenetically distributed into nearly identical genetic strains which show divergent clinical presentations including differences in rates of cardiomyopathy in humans, different vector species and transmission cycles, and differential congenital transmission in a mouse model. The population structure of these strains divides into two groups, which are geographically and clinically distinct. The aim of this study was to compare the transcriptome of two strains of T. cruzi, Sylvio vs. Y to identify differences in expression that could account for clinical and biochemical differences. We collected and sequenced RNA from T. cruzi-infected and control Human Foreskin Fibroblasts at three timepoints. Differential expression analysis identified gene expression profiles at different timepoints in Sylvio infections, and between Sylvio and Y infections in both parasite and host. The Sylvio strain parasite and the host response to Sylvio infection largely mirrored the host-pathogen interaction seen in our previous Y strain work. IL-8 was more highly expressed in Sylvio-infected HFFs than in Y-infected HFFs.

My Four Thousand Bibles

This collection exhibits the relationships between generations of mothers and daughters that are often frayed by misgivings about each others’ perspectives and situations. My Four Thousand Bibles is an emotive critique of ideologies that yield these generational problems, while it embraces the fluidity of spirit, being both intimate and echoing. The collection traces an arch of disquietude from a pressurized girlhood, which for the speaker bears the inevitable condition of guilt, unknowingness, and loving faith. Complemented by the records of her grandmother from poor Appalachia and by the challenges of love and partnership, the speaker’s understanding of herself and her position in time develops patience as an observer and participator in the world’s larger turning.

Absolutely Continuous Spectrum for Parabolic Flows/Maps

This work is devoted to creating an abstract framework for the study of certain spectral properties of parabolic systems. Specifically, we determine under which general conditions to expect the presence of absolutely continuous spectral measures. We use these general conditions to derive results for spectral properties of time-changes of unipotent flows on homogeneous spaces of semisimple groups regarding absolutely continuous spectrum as well as maximal spectral type; the time-changes of the horocycle flow are special cases of this general category of flows. In addition we use the general conditions to derive spectral results for twisted horocycle flows and to rederive spectral results for skew products over translations and Furstenberg transformations.