This dissertation comprises three chapters. The first chapter develops a research design to estimate the causal effect of parental layoffs and income during adolescence on children's college outcomes, and implements this design on administrative data for the United States. The design compares outcomes of children whose fathers lose jobs before college decisions with outcomes of children whose fathers lose jobs after college decisions. I find that layoffs and unanticipated income losses during adolescence have very small adverse effects on future college outcomes. These effects are smaller than estimates in prior work based on firm closures rather than timing of layoffs. I replicate these larger estimates and show they are driven by selection of workers into closing firms. The findings suggest that relaxing parental liquidity constraints during adolescence will do little to increase enrollment compared to improvements in financial aid, especially for low-income children. The second chapter, written with my advisor and other colleagues, shows that classroom quality in early childhood has large causal impacts on adult outcomes, and that test score gains can help to identify classroom quality even when these gains fade out over time. We first link administrative data to records from Project STAR, in which 11,571 students in Tennessee and their teachers were randomly assigned to classrooms within their schools from kindergarten to third grade. We then document four sets of experimental impacts. First, students in small classes are more likely to attend college and exhibit improvements on other outcomes. Second, students who had a more experienced teacher in kindergarten have higher earnings. Third, students who were randomly assigned to higher quality classrooms in grades K-3 -- as measured by classmates' end-of-class test scores -- have higher earnings, college attendance rates, and other outcomes. Finally, the effects of class quality fade out on test scores in later grades but gains in non-cognitive measures persist. The third chapter explores theoretical properties of markets for "credence goods." Credence goods such as health care involve consumer reliance on expert diagnosis. When consumers observe expert cost functions, competitive markets tend strongly toward efficiency. I argue that consumers do not observe expert cost functions and extend an existing model to incorporate this insight. The key result is that prices and competition no longer eliminate mistreatment. / Economics

The petroleum industry has been utilizing surfactant stabilized foams for mobility control and enhanced oil recovery applications. However, if surface-treated nanoparticles were utilized instead of surfactants, the foams could have a number of important advantages. The solid-stabilized foams are known to have a much better stability than the surfactant-stabilized foams, because the energy required to bring nanoparticles to, and detach from the foam bubble surface is much larger than that of surfactants, and thus the resulting foam will be more stable. Since nanoparticles are the stabilizing component of the foam and are solid, they have potential to stabilize foam at high temperature conditions for extended periods of time. Since they are inherently small, nanoparticles, as well as the foam that they stabilize, can be transported through rocks without causing plugging in pore throats. Stable supercritical carbon dioxide-in-water foams were created using 5 nm silica-core nanoparticles whose surface had short polyethylene-glycol chains covalently bonded to it. The foams were made by injecting CO2 and an dispersion of with surface-treated nanoparticles simultaneously through a glass-bead pack. The fluids flowing through this permeable media created shear rates of about 1350 sec-1. Nanoparticle concentration, nanoparticle coating, water salinity, volume ratios between CO2 and water, temperature and shear rates were systematically varied in order to define the range of conditions for foam generation. Using de-ionized water to dilute the nanoparticle concentration, we were able to generate stable foams were at nanoparticle concentrations as low as 0.05 weight percent. Among the different surface coatings that we tested PEG coatings were the only type that was able to stabilize foam. As the salinity of the aqueous phase increased, the nanoparticle concentration required to maintain foam also increased; for example, 0.5 weight percent nanoparticles were required for 4 weight percent NaCl brine. Foam stability was weakly correlated with volume ratios as foams were made across ratios from two to fourteen, and the normalized viscosity ratio increased with the increase of the phase ratio. Foams were created at temperatures up to 95 degrees Celsius. Foam generation was also determined to require a critical shear rate, which increased with temperature. When foam was stabilized by the nanoparticles, the foam exhibited an increase of between two and twenty times in the resistance of flow compared to the two fluids flowing without nanoparticles. / text

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The city landscape of China is undoubtedly experiencing rapid transformation. With the fast rate of urbanization it seems plausible that people will live in a vertical city served by new kinds of transportation infrastructure around the year 2050. This project studied the values of the upper middle class of migrants living in a future Shanghai. Ideation and form development resulted in an aesthetic sculpture informed by the western brand and the eastern culture. This sculpture then inspired the development of a vehicle concept that can act as mobility solution as well as an icon of quality living in the future Chinese home.

During the last decade, the Denton Research Group has made significant advancements in the field of real time direct vapor detection of low volatile explosives under ambient conditions. An ion source plays a crucial role in the sensitive detection of traces of compounds in gas phase by ion mobility spectrometry, but, all the current ionization techniques have significant drawbacks and do not fully satisfy all needs. To overcome the limitations associated with either hazards from a radiogenic ion source or poor reliability from the current non-radiogenic ion sources, the author of this dissertation has undertaken the development of an entirely new ion source based on dielectric barrier discharge technologies. This dissertation describes the development, characterization, and applications of novel dielectric barrier discharge (DBD) ion sources for ion mobility spectrometry. The sources under investigation are non-radiogenic, highly reliable, and provide a high yield of ions. The difficulty of extracting ion current from a traditional dielectric barrier discharge was solved by using an array of tiny discharges formed at the crossing points of two crossed sets of glass coated wires. The relationship of the excitation voltage, frequency, and extraction field for AC excitation on the extracted ion current were studied. The dielectric barrier discharge ion source were also excited in pulse mode by fast-rising and fast-falling high voltage pulses. A high voltage switch using serial MOSFETs was specially designed for driving the dielectric barrier discharge ion source in pulse mode. Application of this dielectric barrier discharge ion source to ion mobility spectrometry was demonstrated with the measurement of limit of detection and direct vapor detection of explosives.

No description available.

The development of new technologies and the advancement of existing technical expertise can allow for dramatic improvements to be realized in analytical instrumentation. The development of an integrating solid-state ion detector, designed to have a high sensitivity as well as maintaining a high-level of stability, is described and evaluated. Several versions of the charge-transimpedance amplifier (CTIA) technology were constructed with different operating features. The CTIA-1 is a 32-pixel array detector designed for mass spectrometry. It has the capability to simultaneously detect multiple ion channels with a detection limit less than 100 ions. The CTIA-2 detector features an independent selectable gain for each detection channel. The CTIA-2 is a 4-channel device designed for ion mobility. Further design features were built into the CTIA-5 such as differential noise reduction capabilities.The CTIA-1 technology was evaluated for use in isotope ratio mass spectrometry on a custom-built Mattauch-Herzog mass spectrometer. An evaluation was conducted in terms of the detector sensitivity, stability, accuracy, precision, resolution, and mass bias. The CTIA-2 was tested on a sector mass spectrometer for its response to low ion currents of both positive and negative ions. The detector stability, its accuracy, and its precision were studied.The technique of ion mobility spectrometry is rapidly growing, as it is the main technology used for the detection of explosives at security checkpoints. The need to improve the sensitivity of existing ion mobility instruments has led to the exploration of using the CTIA detector in ion mobility instruments. Improvements in sensitivity of two to three orders of magnitude have been demonstrated using the described CTIA detectors. Additional applications that use ion mobility instruments for the detection of analytes have been presented, the chemical mapping of a halogen-contaminated sand bed, the detection of pesticides, as well as the detection of TNT in drinking water.Results indicate that the CTIA detector technology is well suited for use in both mass spectrometry and ion mobility. The sensitive and stable multi-array CTIA detectors perform well in isotope ratio mass spectrometry. Ion mobility instruments of all types can benefit from the added sensitivity supplied by this technology.

No description available.

Ready to Roll? Understanding Activity, Mobility and Life Satisfaction among Residents Who Use Wheelchairs

This anthropological, ethnographic study investigates the mobility patterns of Maritimers within Canada, with a focus on political economy. Specifically, I have analyzed the links between mobility, livelihood and identity within Miramichi, New Brunswick, as indicative of broader mobility patterns. This analysis is based on ethnographic data gathered over the course of two sessions of fieldwork in Miramichi itself, phone interviews with people who had moved away from the area, and extensive research of the historical regional political economy. I argue the historical and global context of the political economy and predominance of natural resource-based industries in the area are intricately related to mobility decisions. These contexts have also influenced understandings as to what work is available in the area and what is considered to be “good” work. Local understandings of livelihood are intricately linked to mobility decisions, which take many different and complex forms. I formulate a typology of the various mobility patterns which emerged from the data collected. Out-migration takes place largely for two reasons: for education and for work. Commuter migrants leave the community for work purposes, at varying distances, but maintain their household or home in Miramichi. In-migration takes place with the two main categories: retirees, many of whom lived in Miramichi during their youth and have “come back”; and educated people in-migrating for employment. This work also contributes to the greater understanding of the potential role communal ties, attachment to place and sentiments contribute to mobility decision-making. My analysis of social sentiments surrounding mobility in relation to notions of community, drawing on the concept of structures of feeling, lead to the formulation of the concept of nostalgic resilience. The nostalgic remembrances of the community past can lead to collective ideas that it was resilient and thus would persist, and even thrive, in the future. In arguing the Miramichi area has ongoing patterns and understandings of mobility, though, I am careful to note that there are negative lived realities in connection with these patterns. Nor are the nostalgic notions of community resilience without negative aspects.