Sociologists have long studied mate choice patterns to understand the shape of stratification systems. Romantic pairing involves intimacy and trust, and is therefore a prime indicator of the extent to which members of different social groupings (race/ethnicity, social class, education, religion) accept each other as social equals. The majority of this literature focuses on marriage, given the commitment marriage implies and the availability of nationally-representative data. In this dissertation, I examine the opposite end of the relationship spectrum: The initial screening and sorting process whereby strangers consider each other as potential mates; express interest in some subset of this population but not others; and find that this interest is or is not reciprocated. This beginning stage in mate choice is particularly important for our understanding of social boundaries because personality factors are likely to matter less and social characteristics to matter more. Yet because these initial forays into relationships are typically unobserved, we know very little about whom people consider as potential mates in the first place. I ask the following questions, corresponding to three empirical chapters: First, how do individuals from different status backgrounds vary in the types of strategies that they pursue and the degree of success that they achieve? Second, what underlying dynamics of homophily, competition, and gender asymmetry give rise to observed patterns of interaction, and under what circumstances do some of these boundaries break down? Third, how do strategies as well as preferences vary at different stages of selection, and at what point is homogeneity created? To answer these questions, I use detailed longitudinal data from a popular online dating site. These data are particularly useful for the study of social inequality not only due to the unique quantity and nature of information that is available, but also because online dating has become one of the primary ways that singles meet and marry today. / Sociology

Mixing is a common feature of stratified fluids. In stratified fluids the density varies with the height. This is true for the most fluids in geophysical environments, like lakes, the atmosphere or the ocean. Turbulent mixing plays a crucial role for the overall energy budget of the earth and has therefore an huge impact on the global climate. By introducing the mixing efficiency, it is possible to quantify mixing. It is defined as the ratio of gain of potential energy to the injection of mechanical energy. In the ocean energy provided by tidal forces leads to turbulence and thus highly dense water is lifted up from the deep sea to the surface. For this process, a mixing efficiency of 0.2 is estimated. Until now it is not completely understood how this high value can be achieved. Thus we measured the mixing efficiency by using a Couette-Taylor system, which can produce steady-state homogeneous turbulence. This is similar to what we find in the ocean. The Couette-Taylor system consists of two concentric cylinders that can be rotated independently. In between a stratified fluid is filled using salt as a stratifying agent. In the laboratory experiment, we obtained mixing efficiencies in the order of 0.001 as a result. Moreover we found that the mixing efficiency decreases with decreasing stratification like previous laboratory experiments have shown. As this value is two orders of magnitude smaller than what we find in the ocean, further studies will be necessary. / text

This research investigated the basis upon which undergraduates construct notions of social honor and the role higher educational institutions play in the consolidation of status group cultures in Mexico. The topics I analyzed included the criteria college students use to evaluate the worthiness of their peers and friends and the meaning they attach to studying at certain higher educational institutions. This study drew primarily on 65 in-depth interviews and four focus group sessions with 15 students enrolled at socioeconomically stratified private and public higher educational institutions in a large city. I also relied on an institutional analysis of the higher educational institutions where I did my research to complement the analysis. The findings of this research show that there are institutional similarities in relation to the moral criteria undergraduates use to evaluate the worthiness of their friends and peers. However, there are important institutional differences showing that Mexico’s system of higher education attracts and trains at least four status groups. The status groups cultures associated with educational credentials show that there are significant cultural and socioeconomic distinctions within the high cost private sector. In particular, there is a clash between an old pedigree status group for which social connections are of outmost importance and a new emerging upper-middle class that competes through the rigorous academic training its undergraduates receive. The other two status groups are composed of lay and large public universities that attract middle-class students and demand-absorption institutions that train students who did not gain admission to public universities or who want to avoid the negative stereotypes associated with public universities. Undergraduates from these two last groups occupy the bottom of the occupational and prestige hierarchy. This research also shows that most of the internal hierarchies undergraduates use to rank their peers do not transcend the walls of a specific college. However, the testimonies of high class students revealed that members from this social stratum determine the worthiness of others based on residential location. This dissertation also shows that socioeconomic and cultural boundaries provide some of the most important sources of symbolic divisions among college students in Mexico. / text

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Earnings inequality had been rising in the United States since the late 1970s. However, at the level of individual states earnings inequality has been rising, stable, and even falling in some states at different points in time. States vary in both the degree and character of change in earnings inequality, the extent to which they have experienced various inequality-increasing developments, and their institutional capacity to mediate these developments. I argue in this dissertation that this variation offers a rich opportunity for comparative analysis and an excellent lens for exploring the dynamics of the recent rise in earnings inequality.In this dissertation I utilize multiple methods and a state-level analysis to explore a number of research questions. What are the major factors driving rising state earnings inequality between 1980 and 2007? To what extent have states taken distinct causal paths to higher levels of inequality? How have states differed in terms of the types of wage growth that have result in rising, stable, or falling inequality? Throughout, special attention is paid to the manner in which state institutional arrangements, such as union strength and minimum wage rates, may mediate various inequality-increasing developments. Additionally, there is a focus on the contribution of industry flows, specifically losses of manufacturing employment and increasing employment in financial, technology and health-related occupations, to regional patterns of change in inequality.Overall, the intensity, timing, and number of factors that have converged upon any particular state vary substantially between regions and over time. A broad finding of this dissertation is that the net impact of many inequality-increasing factors is contingent upon a state's economic condition and institutional character. In particular, state institutional arrangements have powerfully mediated the impact of various inequality-increasing developments. Also, these analyses suggest that industry shifts have substantially impacted state earnings distributions and are critical to understanding regional patterns of change in earnings inequality. In closing, I suggest that much research on rising inequality at the national-level does not fully capture the substantial diversity of state experiences with rising inequality or the complexity of the interactions between the various factors producing those distinct experiences.

Ce travail comporte deux parties dont la première concerne l'ensemble asymptotique d'une application polynomiale $F : \C^n \to \C^n$. Dans les années 90s, Z. Jelonek a montré que cet ensemble est une variété algébrique complexe singulière de dimension (complexe) $n-1$. Nous donnons une méthode, appelée méthode façon, pour strati fier cet ensemble. Nous obtenons une strati cation de Thom-Mather. En utilisant les façons, nous donnons un algorithme pour expliciter l'ensemble asymptotique d'une application quadratique dominante en trois variables. Nous obtenons aussi une liste des ensembles asymptotiques dans ce cas. La deuxième partie concerne l'ensemble $V_F$ , appelé l'ensemble des Valette. L'année 2010, Anna et Guillaume Valette ont construit une pseudo-variété réelle $V_F \in R^{2n+ p}$, où $p > 0$, associée à une application polynomiale $F : C^n \to C^n$. Dans le cas $n= 2$, ils ont prouvéque si $F$ est une application polynomiale de déterminant jacobien partout non nul, alors $F$ n'est pas propre si et seulement si l'homologie (ou l'homologie d'intersection) de $V_F$ n'est pas triviale en dimension 2. Nous donnons une généralisation de ce résultat, dans le cas d'une application polynomiale $F= (F_1, \ldots, F_n : \C^n to \C^n$ de jacobien partout non nul. Nous donnons aussi une méthode pour stratifi er l'ensemble $V_F$ . Comme applications, nous avons les strati cations de l'ensemble $K_{\infty}F$ des valeurs critiques asymptotiques de $F$, de l'ensemble $B(F)$ des points bifurcation de F.

The racial wealth gap is a deeply inexorable indicator of inequality. Today the average family of color holds only six cents of wealth for every dollar owned by whites. What accounts for such stubborn inequality in an era lauded as racially progressive? Intergenerational family links suggest a major linchpin. In this dissertation I work toward a race critical theory of social reproduction, drawing on 156 family histories of intergenerational wealth transfer. These data were categorically coded for instances of wealth and capital acquisition and transfer, as well as qualitatively analyzed for thematic patterns using the extended case method. My analysis targets specific social mechanisms that differentially promote the transmission of wealth and other forms of capital (e.g., social networks, educational credentials) across racial groups over time. I isolate racial patterns in the mobility trajectories of families through an original construct, inheritance pathways – instances involving the transfer and/or interconvertiblity of wealth/capital between two or more generations. Among my sample, inheritance pathways were regularly traceable from ancestors living during legal slavery and segregation. My analysis reveals that the wealth and capital acquired by white families regularly works in interlocking, supportive ways to “pave” pathways of protected, intergenerational mobility over time. In contrast, though families of color evidence many efforts to build upwardly mobile pathways, they are frequently divested of their capital through both explicitly and subtly racist means. Moreover, the value of their capital is often diminished, making it less useful in launching and sustaining mobility pathways. My analysis hones in on the recursive relationship between micro level family actions and the racial state, which is regularly implicated in these processes. I draw on these data to additionally expand the concept racial capital – a type of “currency” that intersects with other forms of capital for individuals, families and groups. Collectively, the inheritance pathways of families suggest that whiteness often intervenes to (1) “unlock” forms of capital for some individuals/families/groups; and, (2) enhance the value of other forms of capital. Ultimately I argue that inheritance pathways and racial capital serve as primary means for reproducing conditions and meanings that sustain systemic racism over time.

A novel multi-tank thermal energy storage (TES) was evaluated experimentally and numerically. The multi-tank storage is based on the interconnection of standard hot water storage tanks by a single charge flow loop. Each tank is charged through a thermosyphon loop and natural convection heat exchanger (NCHE). Both series- and parallel-connected configurations were investigated and results show that high degrees of stratification can occur. To predict the performance of the series- and parallel-connected multi-tank TES, a numerical model was developed and implemented in the TRNSYS simulation environment. Laboratory tests were also conducted to measure the unit’s performance under charge conditions representative of combinations of clear and overcast days. The effects of rising and falling charge loop temperatures and power levels on storage temperatures and heat transfer rates were studied and indicated that sequential stratification was achieved in the series-connected storage. Under certain conditions, reverse flow through the thermosyphon loops was identified, leading to destratification and carry-over of heat to the downstream storage tanks. Consequently, a new model was developed and showed to model reverse thermosyphon operation. A subsequent analysis showed that these effects could be minimized by careful system design. To quantify the relative benefits of the sequentially stratified TES, values of exergy stored versus time were determined and compared against fully stratified and fully mixed storages. Results show that the series configuration closely matches the exergy level attained by a perfectly stratified storage. Finally, annual simulations conducted for a typical multi-family installation showed that the multi-tank storage performed at a level comparable to a single, fully stratified, storage. / Thesis (Ph.D, Mechanical and Materials Engineering) -- Queen's University, 2009-06-24 00:13:01.142

This work is an example of a CFD-assisted design and characterization process for thermal energy storage vessels. A general modeling technique for future works is also proposed. The Short-Term Thermal Storage (STTS) tanks at the Drake Landing Solar Community (DLSC) were used as the principal case study. The performance characterization of the STTS tanks and the evaluation of other tank designs were made under solar charging conditions and for the STTS “Hot Tank” only. Three sets of simulations were undertaken for each tank design, each representing a different state of inlet conditions reflected in the DLSC’s operational manual. Characterization of the STTS tanks was done mainly by applying a set of 2nd Law characterization indices, both existing and new, using exergy as the primary Figure of Merit. It was evident that significant mixing occurs in the current STTS tanks due to the ineffective placement of the inlet ports and the lack of an appropriate flow diffuser to prevent mixing. For example, at the end of the simulations exhibiting constant inlet temperature and flow rate, the total exergy in the original STTS tank was only 68% of a perfectly-stratified vessel. A modified design of the STTS tanks, which only shifted the position of the inlet port and center baffle, significantly improved this value to over 90%. Additional analysis also indicated that the STTS tanks would benefit from a simple flow distributor or inlet manifold that would address stratification issues inherent to variable temperature inlet conditions. However, further analysis on this particular design configuration is needed. The characterization methods employed in this work represent an effective means to differentiate between the stratification effectiveness of various thermal storage vessel designs. This work would further benefit from a future study that compares changes to the STTS tanks’ stratification efficiency with changes to the DLSC’s overall performance, including a cost-benefit analysis. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2009-09-18 05:50:58.362

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