The Asian Monsoon system impacts more than two-thirds of the world’s population each year by supplying the necessary water resources to sustain agriculture, the economy, and the socioeconomic welfare for billions of people. In recent decades, changes in the strength and spatial extent of the monsoon have led to significant drought and flooding events. Currently, climate models do not agree on future changes in monsoonal rainfall. In order to improve projections of changes in the Asian Monsoon, it is important to investigate how the monsoon has varied in the past. Climate proxy records obtained through archives (such as cave deposits) provide evidence for changes in past climate on a range of timescales.

My dissertation focuses on the Southeast Asian region, where few paleoclimate records that span the last 2,000 years currently exist. I present the first, high-resolution speleothem record from northern Laos. The carbon stable isotope (δ13C) record reveals decades-long megadroughts, consistent with previous findings from regional tree ring records, whereas the oxygen stable isotope (δ18O) record, interpreted as changes in monsoon intensity, exhibits a relationship with solar variability. I identify that multidecadal to centennial-scale shifts in monsoon intensity are linked with solar-forced changes in tropical Atlantic sea surface temperatures. I also examine the modern interannual variability of precipitation across East China and Southeast Asia over the last 30 years. I show that spatial tripole and dipole rainfall patterns are linked with the El Niño Southern Oscillation and North Atlantic Oscillation, respectfully. Finally, I evaluate how different water pathways and in-cave properties may influence speleothem δ18O values at our cave site using an integrated speleothem forward model and cave monitoring data. I conclude that combined effects of karst hydrology and in-cave processes contribute to speleothem δ18O variability.

The collective results of my dissertation help us better understand changes in Southeast Asian hydroclimate on a variety of spatial and time scales. This research builds upon the limited number of paleoclimate records from Laos and the surrounding countries, while contributing to modern rainfall analyses and proxy system modeling studies to better interpret paleoclimate records and improve projections of monsoon rainfall.

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Recent findings

This dissertation explores the relationship between the United States and the newly founded United Nations during the presidency of Harry S. Truman. Research for this dissertation consisted primarily of the examination of official documents collected and published by the U.S. Government Printing Office in the series entitled Foreign Relations of the United States,as well as the examination of documents found at the United Nations Archive, New York, New York, the Truman Library, Independence, Missouri, and the U.S. National Archive, College Park, Maryland, as well as on various websites. Additional research consisted of the examination of news articles and opinion pieces published in selected newspapers during the relevant period.

This study found that throughout the Truman presidency the United States maintained an internationalist posture of engagement vis-a-vis the United Nations, but that, under the pressure of the Cold War, the kind of internationalism embodied in U.S. policy at the UN changed from a cooperative, optimistic, Wilsonian internationalism as written into the UN Charter to a much more hard-headed, nationalistic, combative internationalism. In the process, the U.S. government backed various policies which undercut certain underlying UN principles, such as universality of membership and unanimity of "Great Power" permanent members in the Security Council, and as a result weakened the United Nations. Throughout the period the United States enjoyed substantial majority support in the UN Security Council and General Assembly, but in order to maintain that support American policy had to take into consideration, and at various times was modified by, the attitudes of allies and other governments of various middle-level and neutralist powers. American attitudes, both within government and among the public, changed over the course of Truman's presidency, from initial optimism to considerable disappointment, but at no time during Truman's presidency did the U.S. government or the American public desire to give up on the United Nations.

The genetics of heart failure is complex. In familial cases of cardiomyopathy, where mutations of large effects predominate in theory, genetic testing using a gene panel of up to 76 genes returned negative results in about half of the cases. In common forms of heart failure (HF), where a large number of genes with small to modest effects are expected to modify disease, only a few candidate genomic loci have been identified through genome-wide association (GWA) analyses in humans. We aimed to use exome sequencing to rapidly identify rare causal mutations in familial cardiomyopathy cases and effectively filter and classify the variants based on family pedigree and family member samples. We identified a number of existing variants and novel genes with great potential to be disease causing. On the other hand, we also set out to understand genetic factors that predispose to common late-onset forms of heart failure by performing GWA in the isoproterenol-induced HF model across the Hybrid Mouse Diversity Panel (HMDP) of 105 strains of mice. We performed fine phenotyping using serial echocardiograms and controlled for environmental heterogeneity in the experimental setting. As a result, we achieved high heritability estimates of 64% to 84% for all cardiac traits and had superior power for mapping HF-related trait, compared to human studies. Association analyses of cardiac traits, corrected for population structure and multiple comparisons, revealed genome-wide significant loci across the spectrum of cardiac traits. Cardiac tissue gene expression profiling, expression quantitative trait loci, expression-phenotype correlation, and coding sequence variation analyses were performed to prioritize candidate genes and to generate hypotheses for downstream mechanistic studies. Future directions will be to further bridge the gap of understanding between rare Mendelian and common cardiovascular diseases, which together will have wide spread therapeutic implications in delaying or reversing HF progression in human populations.

This research investigates the feasibility of offering demand-responsive transit (DRT) service to the general public in situations of low demand density. The study region is AC Transit District 2 which consists of the cities of Fremont and Newark, California.

We developed a methodology to evaluate operating efficiencies of existing bus lines and line segments, and identified areas suitable for DRT service based on year 2001 data. We proposed an alternating strategy of checkpoint DRT service and compared it to other strategies. The report also described the schema for an automated reservation and scheduling system.

Our initial findings are: the service cuts and route changes implemented by AC Transit district 2 after 2001 largely concur with our analysis of the 2001 system; by making very limited additional changes to the fixed routes and using the proposed checkpoint service, AC Transit could have a net savings of 2-3 buses; and finally, this service offers considerable advantage in passenger access, reliability and service cost.

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