The intricate concepts of ad-hoc polymorphism and overloading permeate the field of programming languages despite their somewhat nebulous definitions. With the perspective afforded by the state of the art, object-oriented Fortress programming language, this thesis presents a contemporary account of ad-hoc polymorphism and overloading in theory and in practice. Common language constructs are reinterpreted with a new emphasis on overloading as a key facility. Furthermore, concrete problems with overloading in Fortress, encountered during the author's experience in the development of the language, are presented with an emphasis on the ad hoc nature of their solutions. / text

Liquefaction is a phenomenon that occurs in loose saturated sand deposits that are subjected to earthquake loading. This phenomenon can cause massive displacements and significant destruction. Many methods for mitigating liquefaction have been proposed and investigated including compaction, drainage, and grouting. One such liquefaction mitigation technique involves the addition of bentonite fines to the pore spaces of a loose, saturated sand via permeation of an engineered clay suspension. This method of soil improvement has provided the basis and motivation for this research. Also, the effect of plastic and non-plastic fines on the static and cyclic response of sands is somewhat contradictory throughout the literature. Thus, the primary objective of this study was to characterize the affect of an engineered bentonite pore fluid on the undrained monotonic response of loose, saturated Ottawa sand in order to determine its feasibility for use as an effective method for liquefaction mitigation. The permeation of engineered bentonite suspensions is proposed as a passive site remediation technique. Thus, the suspensions were delivered to loose Ottawa sand specimens in the laboratory by permeation in a newly designed three-way split mold. This split mold was used to create easily tested specimens that would have an initial soil fabric similar to that expected after permeation in the field. The bentonite suspensions were treated with sodium pyrophosphate to reduce the initial yield stress and viscosity in order to allow for permeation. Three different bentonite suspensions were utilized throughout this study each having different properties and delivering slightly different amounts of bentonite to the loose, saturated sand. The affect of this engineered pore fluid on the undrained shear response of loose, saturated Ottawa sand was compared to the undrained shear response of clean sand and dry-mixed sand and bentonite. The specimen preparation method (dry-mixed or permeated) was shown to have a significant effect on the response of the sand specimens. While the dry-mixed specimens produced larger and more sustained positive pore water pressures than the clean sand (resulting in an increased tendency to flow), the permeated specimens showed a marked decrease in the generation of excess pore water pressures, displayed a more dilative response, and thus resulted in a soil structure that was less likely to flow. Finally, the results of tests on specimens permeated with engineered bentonite suspensions show that there is little to no change in the effective friction angle at critical state. A method for effectively testing permeated soil specimens was developed in this study. This method has laid the framework for further investigations into the use of engineered bentonite suspensions for liquefaction mitigation by permeation grouting. / text

We present updated observations of a pilot survey of 14 pulsating DA white dwarfs, monitored for evidence of center-of-mass motion caused by a planetary companion. We have nearly doubled the number of periodicites for which we can produce O-C diagrams that document pulse arrival times from our stars, and have implemented a method to minimize the apertures we use in our reductions in order to reduce sky noise. In addition to a previously published candidate, GD66, we have identi fed at least four more systems worthy of rigorous observational follow-up. We have also implemented a method, a generalized Lomb-Scargle periodogram, that takes into account weighted points in order to characterize any periodic behavior present in our O-C diagrams. For at least one DAV within this same sample, we have found strong observational evidence for an evolutionary time scale (via the rate of period change) that is inconsistent with cooling alone. In that star, WD0111+0018, we report for the first time measurement of the rate of period change of nonlinear combination frequencies in a pulsating white dwarf. We speculate that this may be caused by a changing rotation rate that aff ects only modes with m not equal to 0. / text

Stacked storage systems are a viable carbon management operation, especially in regions with potential growth in CO₂ enhanced oil recovery (EOR) projects. Under a carbon constrained environment, the industrial Texas Gulf Coast is an ideal area for development of stacked storage operations, with a characteristically high CO₂ intensity and abundance of aging oil fields. The development of EOR along the Texas Gulf Coast is limited by CO₂ supply constraints. A stacked storage system is implemented with an EOR project to manage the temporal differences between the operation of a coal-fired power plant and EOR production. Currently, most EOR operations produce natural CO₂ from geologic formations. A switch to anthropogenic CO₂ sources would require an EOR operator to handle volumes of CO₂ beyond EOR usage. The use of CO₂ in an EOR operation is controlled and managed to maximize oil production, but increasing injection rates to handle the volume of CO₂ captured from a coal plant can decrease oil production efficiency. With stacked storage operations, a CO₂ storage reservoir is implemented with an EOR project to maintain injection capacity equivalent to a coal plant's emissions under a carbon constrained environment. By adding a CO₂ storage operation, revenue can still be generated from EOR production, but it is considerably less than just operating an EOR project. The challenge for an efficient stacked storage project is to optimize oil production and maximize profits, while minimizing the revenue reduction of pure carbon sequestration. There is an abundance of saline aquifers along the Texas Gulf Coast, including the Wilcox, Vicksburg, and Miocene formations. To make a stacked storage system more viable and reduce storage costs, maximizing injectivity is critical, as storage formations are evaluated on a cost-per-ton injected basis. This cost-per-ton injected criteria, also established as injection efficiency, incorporates reservoir injectivity and depth dependant drilling costs to determine the most effective storage formation to incorporate with an EOR project. With regionally adequate depth to maximize injectivity while maintaining reasonable drilling costs, the Vicksburg formation is typically the preferred storage reservoir in a stacked storage system along the Texas Gulf Coast. Of the eleven oil fields analyzed on a net present value basis, the Hastings field has the greatest potential for both EOR and stacked storage operations. / text

With this study I aim to understand the role of social networks of migration as very special catalysts of change in the countries of origin of important labor migration streams, particularly in the case of the emergent and second most important system of migration in which Latin Americans participate, i.e. the South European Migration System. I pursue this aim through the means of examining the characteristics and mechanisms of operation of ego – centered social networks of migration that are active within the migration streams from Argentina and Peru to Italy and Spain, therefore: (1) I examine the two different institutional contexts that contribute to the shape of the mentioned social networks of migration in Argentina and Peru; (2) I study the structure of these networks (which comprises characteristics such as size, density, and degree of heterogeneity); their resources and mechanisms of operation ; and (3) I discuss the main possible causal influences that these social networks of migration exert in the countries of origin of the emigration streams I study, namely Argentina and Peru, considering the very specific characteristics these social networks have in each one of the country cases. In order to discuss these causal influences, I examine their impact on children residing in Argentina and Peru who are members of migrant sending households, and I specifically analyze impacts on their living arrangements. I use quantitative and qualitative data on the emigration streams from Argentina and Peru to Italy and Spain which I collected during 2006, 2007 and 2008 , in Buenos Aires (Argentina) and Lima (Peru). Quantitative data was collected using a small household survey targeting relatives of migrants to Spain and Italy, in both cities (Argentina – Italy: n=75, Argentina – Spain: n= 245, Peru – Italy: n= 206, and Peru – Spain: n=398). Qualitative data included expert interviews (n=5 for Peru and n=7 for Argentina); and different types of semi-structured in- depth interviews targeting relatives of migrants to Spain and Italy in different household positions, including children 12 -18 years old (n=11 for Peru, and n=11 for Argentina). / text

Abstract: Black immigrants are a demographically and socially important group in the United States. Between 1960 and 2005 the foreign-born share of the entire black population increased twenty-two fold. Furthermore, this group also accounted for more than 20% of the growth in the black population in the 2000s. In spite of the rapid growth of the black immigrant population, few studies have evaluated their health and labor market outcomes. The existing literature on black immigrants demonstrates that this group has health outcomes that are substantially different from those of other immigrant populations. Research illustrates that most black immigrants arrive in the United States with better health than black Americans and maintain this health advantage after more than two decades in the United States. This phenomenon is particularly pronounced among African immigrants. Research in this area also demonstrates that certain subgroups of black immigrants, such as West Indians, have superior labor market outcomes compared to black Americans. Because of the phenotypic similarities between these two groups, these findings have led some scholars and policymakers to question the salience of discrimination and racism in determining the labor market outcomes of black Americans. This dissertation expands the literature on the health and labor market outcomes of black immigrants by evaluating the salience of the major sociological theories, including immigrant versus native culture, bias of whites toward black immigrants over black Americans, and selective migration in explaining differences in labor market outcomes between black immigrants and black Americans. In an effort to better understand the unique health patterns among black immigrants, this dissertation also advances and tests a conceptual model that evaluates whether social, economic, and health conditions within the sending countries of black immigrants explain variations in health and disability among these immigrants. This dissertation uses data on males from the 1980-2000 U.S. Censuses and the 2001-2007 American Community Survey to estimate wage, employment, and self-employment models to determine if black immigrants have outcomes that resemble those of native blacks (collectively) or native black internal migrants. The results suggest that migration selectivity is important in explaining wage and employment differences between black immigrants and black natives. However, migration selectivity plays a limited role in explaining self-employment differences between black immigrants and black natives. This general finding is produced when black immigrants are evaluated collectively and when they are separated by both region and country of birth. This result suggests that differences that exist between black immigrants and black natives are the result of selective migration rather than culture. This work is the first to provide a comprehensive analysis of the importance of selective migration in explaining labor market differences between black Americans and black immigrants from all the major sending regions and countries of the world. This work also uses data on black immigrants from the 1996, 1998, 2000, 2002, 2004, 2006, and 2008 March Current Population Survey to evaluate the role that conditions in immigrants’ countries of origin play in explaining variation in health and disability among black immigrants in the United States. Estimates from reduced form health and disability models show that these outcomes are more favorable for immigrants who migrate from countries with high combined enrollment ratios, low income inequality, and high life expectancy. The results also demonstrate that country of origin conditions explain some portion of differences in health among immigrants. / text

A digital logic circuit tends to become slower if the voltage (VDD) level drops below the normal VDD level. Because of this, the required data will not have settled before the arrival of the clock edge. This results in an incorrect sampling of the data leading to a functional failure of the chip. This thesis proposes a clock controller circuit which solves this issue. It consists of a voltage monitoring circuit to track the variations in the VDD level, a frequency multiplier and divider, and a selector logic circuit that outputs a particular frequency depending upon the VDD range in which the chip is operating. / text

The implementation of high-speed passenger trains (HST) within existing highway right-of-way (ROW) offers a solution for regions with a demand for the capacity and service offered by HST but lacking the support for sharing freight rail ROW or acquiring new ROW corridors. The states of Florida, Colorado, California and Nevada propose to use highway ROW for their HST projects to increase the capacity of the corridor, prevent or minimize impacts and prevent disruption of freight rail operations. Despite the constraints of using existing highway ROW, such as speed-limiting degrees of curvature and safety concerns, solutions and mitigation measures exist. The purpose of this thesis is to present the HST projects in the United States proposing use of highway ROW, the potential benefits and engineering issues to consider and the feasibility of using the existing I-35 ROW in Texas for HST. / text

Oxide interfaces have attracted considerable attention in recent years due to emerging novel properties that do not exist in the corresponding parent compounds. Furthermore, modern atomic-scale growth and probe techniques enable the formation and study of new artificial interface states distinct from the bulk state. A central issue in controlling the novel behavior in oxide heterostructures is to understand how various physical variables (spin, charge, lattice and/or orbital hybridization) interact with each other. In particular, density function theory (DFT) has provided significant insight into underlying physics of materials at the atomic level, giving quantitative results consistent with experiment. In this dissertation using density functional theory methods, we explore the electronic, magnetic and structural properties developed near the interface in SrTiO3/LaAlO3, EuO/LaAlO3, Fe/PbTiO3/Pt, Fe//BaTiO3/Pt and Cs/SrTiO3 heterostructures. We study the interplay between physical interactions, and quantify parameters that determine physical properties of hetetrostructures. These theoretical studies help understanding how physical variables couple with each other and how they determine new properties at oxide interfaces. / text

This comparative research looks at intermedia agenda-setting effects between Internet bulletin boards and traditional news media, such as daily newspapers and broadcasting, in both the United States and Korea. By examining this intermedia relationship and the flow of influence by Internet bulletin boards on traditional media during presidential campaigns in the two countries, this dissertation study attempts to extend our knowledge of intermedia agenda-setting research. In addition, it also investigates, in reverse, the effects of daily newspapers and broadcasting on Internet bulletin boards. Finally, attention is given to different types of discussion cultures in the two countries. Results of this dissertation research indicated that there are intermedia relationships between Internet bulletin boards and traditional news media, such as newspapers and broadcasting, at the first and second levels of agenda setting using cross-lagged correlation comparisons. More specifically, at the first level of agenda setting in the United States, the results explained only the influence of newspapers on Netizen opinions posted on Internet bulletin boards. In summary, the results concerning issue agenda in the United States indicate that the U.S. Netizen concentrates more on the issue agenda of newspapers than of broadcasting. In the second level of agenda setting in the United States, cross-lagged correlation comparisons not only indicated the influence of both newspapers and broadcasting on opinions posted on Internet bulletin boards, but they also clarified it in this research. Formerly, there was no attempt to examine attributes of the intermedia agenda-setting functions of the U.S. media. This research now provides an explanation of the apparent relationship between traditional media and the Internet. At the first level of agenda setting in Korea, the result of the cross-lagged correlation suggested that Korean newspaper and broadcasting issue agenda influenced Netizen opinions on Internet bulletin boards. As the result of second-level agenda setting in Korea showed earlier, cross-lagged correlation comparisons presented intermedia agenda-setting functions between both newspapers and broadcasting, and Internet bulletin boards with each other. These findings contrast with results in the United States. / text