Aiming to introduce market mechanisms to an administratively managed and heavily subsidized housing system, the ongoing housing reform in urban China has brought dramatic changes in housing provision and consumption. Chinese households have started to enjoy freedom of housing choice that was not possible in socialist China. Yet, their choices are constrained because of the transitional nature of the current housing system where both institutional forces and market mechanisms operate. It is the goal of this research to examine how these two types of forces interact and how households make their housing choices in the transitional housing system. In contrast to the economic and socio-demographic perspectives on housing choices in the Western literature, I argue that a framework incorporating social relationships between the state, work units and employees is needed to understand households’ housing choice in transitional urban China. Associated with housing choices, the homogenous residential pattern in socialist China is gradually changing and a residential sorting is in process. It is also my goal to study the change of residential patterns and its dynamics in urban China.

Four research questions are proposed: (1) What kinds of individual and household characteristics affect housing choice, and how relevant are the existing Western theories? (2) What are the roles of work units in housing choice in transitional urban China? (3) What is the role of the central state in constraining housing choice in transitional urban China? (4) Is a new form of residential pattern emerging? What factors contribute to the change of residential patterns and how relevant are the existing Western theories? A complementary methodology combining both quantitative and qualitative analyses, both national studies and case studies will be employed. The data include a national survey data, in-depth interviews in three cities, and archival data such as housing policies and housing statistics. A multi-level logistic model will be used to examine individual, household, work unit level and state level factors affecting households’ housing choices, and maps on residential patterns will be created.

The state-of-the-art X-ray source based on inverse-Compton scattering between a high-brightness, relativistic electron beam produced by an X-band RF accelerator and a high-intensity laser pulse generated by chirped-pulse amplification (CPA) has been carried out by our research team at Lawrence Livermore National Laboratory. This system is called "Compact Laser-Compton X-ray Source". The applications include nuclear resonance fluorescence, medical imaging and therapy, and nuclear waste imaging and assay. One of the key factors in this system is how we know the interaction happened in the vacuum chamber, which is the spectrometer of electron beams. The other key factor is the interaction after the spectrometer, which is the outgoing X-ray. In this thesis, the work in the simulation for the result of the interaction between electrons and the laser, the calibration of spectrometer, and laser focus characterization are discussed.

Based on their connectivity, network glasses can be classified as flexible, stressed–rigid, or isostatic, if the number of topological constraints is lower, larger, or equal to the number of atomic degrees of freedom, respectively. Thanks to the absence of any stoichiometric requirement, the rigidity of glasses can be continuously tuned (e.g., from flexible to stressed–rigid) by changing their chemical composition. Interestingly, optimally-constrained isostatic glasses have been noted to exhibit unusual properties (e.g., nearly-reversible glass transition, low relaxation, desirable mechanical properties, etc.). Especially, the non-aging intermediate state features an almost vanished endotherm between the first and second heat scan across glass transition, providing a pathway for phase change material optimization in the application of non-volatile rewriteable media. However, the physical origin of the unusual behaviors and properties of isostatic glasses remain unclear.This thesis begins with investigating how the flexible-to-rigid transition in network glasses is encoded in their energy landscape based on molecular dynamics simulations. To this end, we introduce a simplified, yet realistic model of network glasses with varying connectivity. We characterize the topography of these glasses by adopting the activation-relaxation technique (ART), which enables a systematic search of saddle points and transition pathways in the energy landscape surface. We then demonstrate that the flexible-to-rigid transition arises from an interplay between low-energy saddle points (in flexible glasses) and topological frustration (in stressed–rigid glasses). Also, by utilizing the ring structure, we expand the transition correlation with ring size distribution. Meanwhile, we highlight the local heterogeneity with all the energy landscape features by dicing the model into small cubes. Comparing within a single glass helps exclude the effect of different configurations, further consolidating our conclusion on the physical origin of rigidity transition. Finally, to explore the role of chemistry effect in rigidity transition, we compare the behavior of the simple connectivity model with a realistic GexSe1-x model. With the similar shape of enthalpic differences, the realistic model could reveal the effect of glass-forming ability with experimental results where the simple model fails. Overall, we have a clear pathway towards understanding the physical origin of rigidity transition of GexSe1-x glass.

One decision very few high school student-athletes are faced with is which Division I athletic scholarship to accept. These highly coveted scholarships can cover for all expenses and provide support during and after the undergraduate experience. Yet, even if high school student-athletes accept a Division I offer, it doesn’t guarantee their success. Many athletes struggle with student identity as they try to remain eligible to complete at the Division I level. I draw from identity theory on figured worlds to investigate how student success as a Division I athlete is linked to negotiating their figured world of being a student as it informs their decision about which Division I scholarship to accept. Using data from interviews and observations, this study follows two elite high school student-athletes as they make their decision about which Division I scholarship to accept, and how their dual identities as students and athletes shaped their decision-making process.