Browsing by Subject "mobility"
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Item Intergenerational mobility in earnings in Brazil spanning three generations and optimal investment in electricity generation in Texas(Texas A&M University, 2008-10-10) Marchon, Cassia HelenaThis dissertation contains three essays. The first and second essays examine intergenerational mobility in earnings in Brazil using a data set spanning three generations. I use data from PNAD{a nationally representative household survey in Brazil. I build a three-generations data set consisting of 5,125 grandfather-father- son triplets by restricting the sample to households with adult sons. The first essay estimates some relationships between a child's earnings and family background implied by the Becker-Tomes model. I find that the estimates contradict some of its predictions, like the negative relationship between child's earnings and grandparent's earnings when controlling for parent's earnings. I propose a modified version of the Becker-Tomes model and find that the estimates are consistent with its predictions. I find that family background explains 34.9% of the variation in earnings among young males who live with their parents. If it were possible to eliminate the differences in investment in the children's human capital, the variation in earnings would fall by no more than 21.1%. Additionally, if there were no differences in endowments among children, the variation in earnings would fall by no less than 26%. The second essay examines the evolution of the intergenerational elasticity across generations and im- plications of marriage, education and fertility on mobility. I find that the estimate of the intergenerational elasticity in earnings is 0.847. The elasticity of earnings between son-in-law and father-in-law, 0.89, is approximately the same as the elasticity between son and father, 0.9. Additionally, controlling for fathers' percentile in the earnings distribution, each additional sibling decreases the sons' percentile by 1.77 percentiles. The third essay estimates an indicator of the optimal investment in electricity generation in Texas, and the associated efficiency gains. The essay presents a method to estimate the optimal investment in each technology available to generate electricity. The estimation considers the expected entry and exit of generation plants, future fuel prices, different demand elasticities and a potential carbon allowance mar- kets. Considering a carbon allowance price equal to two times the level in Europe, the optimal investment in electricity generation in Texas is zero.Item Molecular Level Characterization and Mobility of Radionuclide-Carrying Natural Organic Matter in Aquatic Environments(2012-10-19) Xu, ChenRadionuclides, 129I and 239,240Pu, are major products or by-products of nuclear fission and among the top risk drivers for waste disposal at the Savannah River Sites (SRS) and Rocky Flats Environmental Technology Sites (RFETS), respectively, due to their perceived mobility in the environment, excessive inventory, toxicity, and long half-life. The objective of this study is to investigate the role of natural organic matter in retarding or facilitating the migration of 129I and 239,240Pu in the Department of Energy (DOE) sites. Measurements of 127I and 129I in humic acids (HAs) and fulvic acids (FAs) obtained by five successive alkaline, two glycerol and one citric acid-alkaline extractions, demonstrated that these extractable humic substances (HS) together account for 54-56 percent and 46 percent of the total 127I and 129I in the soil, respectively. The variations among 127I and 129I concentrations, isotopic ratios (129I/127I), chemical properties of all these humic substances indicated iodine was bound to a small-size aromatic subunit (~10 kDa), while the large-size subunit (~90 kDa), which likely linked the small-size unit through some weak chemical forces, determined the relative mobility of iodine bound to organic matter. Soil resuspension experiments simulating surface runoff or stormflow and erosion events were conducted with soils collected from SRS. Results showed that 72-77 percent of the newly-introduced I- or IO3- were irreversibly sequestered into the organic-rich soil, while the rest was transformed into colloidal and dissolved organo-iodine by the soil. The resulting iodine remobilization contradicts the conventional view that considers only I- or IO3- as the mobile forms. Quantitative structure analysis by 13C DPMAS NMR and solution state 1H NMR on these humic substances indicate that iodine is closely related to the aromatic regions containing esterified products of phenolic and fomic acid or other aliphatic carboxylic acids, amide functionalities, quinone-like structure activated by electron-donating groups (e.g., NH2) or hemicelluloses-lignin-like complex with phenyl-glycosidic linkage. The micro-molecular environment, such as the hydrophobic aliphatic periphery hindering the active aromatic cores and the hydrophilic polysaccharides favoring its accessibility towards hydrophilic iodine species, play another key role in the interactions between iodine and SOM. NMR spectra of the colloidal organic Pu carrier which can potentially be released from the soil during the surface runoff or stormflow showed Pu was transported, at sub-pM concentrations, by a cutin-derived soil degradation products containing siderophore-like moieties and virtually all mobile Pu.Item Senior Citizens' Adaptive Strategies to Get Around in Their Communities: A Case Study of Yao City, Japan(2012-02-14) Yoshikawa, AyaThis study investigated the relationship between seniors' travel behaviors and living environments and the ways they successfully adapt to the environments, using a sequential mixed method in which qualitative methods follow quantitative analyses. The data were collected from the members of social clubs who regularly visit a community center for the elderly in a mid-size city in Osaka prefecture, Japan. One hundred ninety three seniors participated in the questionnaire survey asking about their daily travel patterns, personal backgrounds, social relations, and environmental information. Twenty-one seniors shared their perceptions of the city and the ways in which they get around through face-to-face interviews, sketch mapping, and one-week travel diary. The findings highlighted cultural and gender influences on seniors' mobility and the proactive nature of their travel behaviors. The participants were relatively healthy and active seniors who travel primarily by bicycle. The statistical analyses indicated that gender did not determine overall or average travel frequency but did identify factors related to high travel frequency. Living near a bus stop and the perception of going out more often than in the past predicted men's high travel frequency (going out every day), while women's high travel frequency was predicted by travel modes (bicycling and walking), sidewalk safety, chores (grocery shopping), and social network (seeing friends and having fewer relatives). Furthermore, the results of qualitative analyses revealed that seniors invented, modified, and applied various adaptive strategies to maintain or enhance their mobility. The positive perceptions of their communities such as favorable memories and beautiful scenery fostered seniors' familiarity and sense of belonging. Seniors used and modified social and environment resources to ensure travel safety. In addition, changes in senior's life stages and travel means manifested gender differences in their adaptive strategies. Men tended to focus on maintaining good health to keep their driver's license, representing their social role as a provider, while women's adaptations related to adjustment to widowhood and travel safety.