Matching Items (43,917)
Description
III-nitride alloys are wide band gap semiconductors with a broad range of applications in optoelectronic devices such as light emitting diodes and laser diodes. Indium gallium nitride light emitting diodes have been successfully produced over the past decade. But the progress of green emission light emitting devices has been limited by the incorporation of indium in the alloy, mainly due to phase separation. This difficulty could be addressed by studying the growth and thermodynamics of these alloys. Knowledge of thermodynamic phase stabilities and of pressure - temperature - composition phase diagrams is important for an understanding of the boundary conditions of a variety of growth techniques. In this dissertation a study of the phase separation of indium gallium nitride is conducted using a regular solution model of the ternary alloy system. Graphs of Gibbs free energy of mixing were produced for a range of temperatures. Binodal and spinodal decomposition curves show the stable and unstable regions of the alloy in equilibrium. The growth of gallium nitride and indium gallium nitride was attempted by the reaction of molten gallium - indium alloy with ammonia at atmospheric pressure. Characterization by X-ray diffraction, photoluminescence, and secondary electron microscopy show that the samples produced by this method contain only gallium nitride in the hexagonal phase. The instability of indium nitride at the temperatures required for activation of ammonia accounts for these results. The photoluminescence spectra show a correlation between the intensity of a broad green emission, related to native defects, and indium composition used in the molten alloy. A different growth method was used to grow two columnar-structured gallium nitride films using ammonium chloride and gallium as reactants and nitrogen and ammonia as carrier gasses. Investigation by X-ray diffraction and spatially-resolved cathodoluminescence shows the film grown at higher temperature to be primarily hexagonal with small quantities of cubic crystallites, while the one grown at lower temperature to be pure hexagonal. This was also confirmed by low temperature photoluminescence measurements. The results presented here show that cubic and hexagonal crystallites can coexist, with the cubic phase having a much sharper and stronger luminescence. Controlled growth of the cubic phase GaN crystallites can be of use for high efficiency light detecting and emitting devices. The ammonolysis of a precursor was used to grow InGaN powders with different indium composition. High purity hexagonal GaN and InN were obtained. XRD spectra showed complete phase separation for samples with x < 30%, with ~ 9% indium incorporation in the 30% sample. The presence of InGaN in this sample was confirmed by PL measurements, where luminescence from both GaN and InGaN band edge are observed. The growth of higher indium compositions samples proved to be difficult, with only the presence of InN in the sample. Nonetheless, by controlling parameters like temperature and time may lead to successful growth of this III-nitride alloy by this method.
Contributors
Hill, Arlinda (Author) / Ponce, Fernando A. (Thesis advisor) / Chamberlin, Ralph V (Committee member) / Sankey, Otto F (Committee member) / Smith, David J. (Committee member) / Tsen, Kong-Thon (Committee member) / Arizona State University (Publisher)
Created
2011
Description
Although one finds much scholarship on nineteenth-century music in America, one finds relatively little about music in the post-Civil-War frontier west. Generalities concerning small frontier towns of regional importance remain to be discovered. This paper aims to contribute to scholarship by chronicling musical life in the early years of two such towns in northern Arizona territory: Prescott and Flagstaff. Prescott, adjacent to Fort Whipple, was founded in 1864 to serve as capital of the new territory. Primarily home to soldiers and miners, the town was subject to many challenges of frontier life. Flagstaff, ninety miles to the north-northwest, was founded about two decades later in 1883 during the building of the Atlantic & Pacific Railroad, which connected the town to Albuquerque, New Mexico in the east and southern California in the west. Although the particular resources of each town provided many different musical opportunities, extant newspaper articles from Prescott's Arizona Miner and Flagstaff's Arizona Champion describe communities in which musical concerts, dances and theatrical performances provided entertainment and socializing for its citizens. Furthermore, music was an important part of developing institutions such as the church, schools, and fraternal lodges, and the newspapers of both towns advertised musical instruments and sheet music. Both towns were home to amateur musicians, and both offered the occasional opportunity to learn to dance or play an instrument. Although territorial Arizona was sometimes harsh and resources were limited, music was valued in these communities and was a consistent presence in frontier life.
Contributors
Johnson, Amber V (Author) / Oldani, Robert W. (Thesis advisor) / Holbrook, Amy (Committee member) / Saucier, Catherine (Committee member) / Arizona State University (Publisher)
Created
2011
Description
The gold standard for bone measurement is DXA (dual energy X-ray absorptiometry). Typically, to observe changes in bone by DXA, a minimum of a 4-month intervention is required. Serum osteocalcin (OST) (a bone formation marker) and quantitative ultrasound (QUS) of the calcaneus can be used as indicators of bone change but the sensitivity and time course of these indices to short term interventions are unknown. The purpose of this study was twofold: to compare monthly changes in OST and QUS in response to jump training and to evaluate the relationship between DXA, OST and QUS. Young women with QUS t-scores less than 1.0 were randomized into a jump training (J) (n=16) or control (C) (n=16). J consisted of a progressive routine of 1 and 2-footed jumping performed 3 days per week for 4 months. Body composition, QUS and OST were measured at baseline, and monthly for 4 months. DXA and 24-hour dietary recalls were completed at baseline and 4 months. Low attrition rate (12.5%) and high compliance (98%) with the exercise intervention was recorded. No significant correlations between QUS and OST existed. No significant differences were observed between groups at baseline in body composition or bone variables. Monthly increases in OST were observed but there were no significant differences over time between groups in any bone variables. OST and QUS may be indicative of short term bone changes but these variables were not specifically sensitive to the jumping intervention in this population of women.
Contributors
Heumann, Kristin Joelle (Author) / Swan, Pamela D (Thesis advisor) / Alvar, Brent (Committee member) / Chisum, Jack (Committee member) / Lee, Chong (Committee member) / Vaughan, Linda (Committee member) / Arizona State University (Publisher)
Created
2011
Description
Temporary bonding-debonding of flexible plastic substrates to rigid carriers may facilitate effective substrate handling by automated tools for manufacture of flexible microelectronics. The primary challenges in implementing practical temporary bond-debond technology originate from the stress that is developed during high temperature processing predominately through thermal-mechanical property mismatches between carrier, adhesive and substrate. These stresses are relaxed through bowing of the bonded system (substrate-adhesive-carrier), which causes wafer handling problems, or through delamination of substrate from rigid carrier. Another challenge inherent to flexible plastic substrates and linked to stress is their dimensional instability, which may manifest itself in irreversible deformation upon heating and cooling cycles. Dimensional stability is critical to ensure precise registration of different layers during photolithography. The global objective of this work is to determine comprehensive experimental characterization and develop underlying fundamental engineering concept that could enable widespread adoption and scale-up of temporary bonding processing protocols for flexible microelectronics manufacturing. A series of carriers with different coefficient of thermal expansion (CTE), modulus and thickness were investigated to correlate the thermo-mechanical properties of carrier with deformation behavior of bonded systems. The observed magnitude of system bow scaled with properties of carriers according to well-established Stoney's equation. In addition, rheology of adhesive impacted the deformation of bonded system. In particular, distortion-bowing behavior correlated directly with the relative loss factor of adhesive and flexible plastic substrate. Higher loss factor of adhesive compared to that of substrate allowed the stress to be relaxed with less bow, but led to significantly greater dimensional distortion. Conversely, lower loss factor of adhesive allowed less distortion but led to larger wafer bow. A finite element model using ANSYS was developed to predict the trend in bow-distortion of bonded systems as a function of the viscoelastic properties of adhesive. Inclusion of the viscoelasticity of flexible plastic substrate itself was critical to achieving good agreement between simulation and experiment. Simulation results showed that there is a limited range within which tuning the rheology of adhesive can control the stress-distortion. Therefore, this model can aid in design of new adhesive formulations compatible with different processing requirements of various flexible microelectronics applications.
Contributors
Haq, Jesmin (Author) / Raupp, Gregory B (Thesis advisor) / Vogt, Bryan D (Thesis advisor) / Dai, Lenore (Committee member) / Loy, Douglas (Committee member) / Li, Jian (Committee member) / Arizona State University (Publisher)
Created
2011
Description
This research explores the socialization and culture of naturopathic students. Naturopathic physicians are a rapidly growing group of health care providers with a different ideology than conventional physicians. At present they work on the margins of the division of labor in health care. Only 15 U.S. states explicitly recognize, regulate, and license their practice, although the number is increasing. Therefore, the professional socialization of naturopathic students is framed within a context of a changing division of labor in health care. The recent growth of naturopathic physicians reflects the American public's increased interest and use of complementary and alternative medicine (CAM). However, these practitioners are not yet accepted as legitimate physicians by most conventional physicians. This research investigates how the professional socialization of students at a naturopathic medical school prepares them to assume their role as CAM providers in a division of labor that is dominated by conventional physicians. The research examines their choice to attend a naturopathic school, formal and informal socialization at the school, and the student culture. The main research site is a four-year, accredited naturopathic medical school where participant observation, intensive interviews, and a survey were used to collect data. Additional data are presented from observations at a national conference of the American Association of Naturopathic Physicians. Results indicate that the student culture and socialization process at the naturopathic medical school differ in some important ways from the previously documented socialization process at conventional medical schools. The average age of naturopathic students is much older than conventional medical students, and a much larger percentage are women. Unlike conventional medical students, who rely heavily on role models and previous knowledge of what it takes to become a medical doctor, naturopathic students select a career path based on values and beliefs that are more aligned with their own than conventional medicine. The formal and informal training and culture of naturopathic students prepares them to work alongside, rather than within, mainstream medicine. The documentation of how a group of CAM practitioners is created contributes to a better understanding of the ever-changing ideology and division of labor in health care.
Contributors
Harrison, Jennifer L (Author) / Sullivan, Deborah (Thesis advisor) / Kronenfeld, Jennie (Committee member) / Damgaard, Anni (Committee member) / Arizona State University (Publisher)
Created
2011
Description
Many educators believe that the path to a better future is a college education. Initiatives that promote college-going cultures are quite commonplace in many public high schools with some offering elective college-prep support programs like Advancement Via Individual Determination (AVID). Yet, certain groups of students are not taking advantage of these opportunities. In the initial AVID sections at a metropolitan high school in the American Southwest, the girls out-numbered the boys 2:1, and the Hispanic girls outnumbered the Hispanic boys by almost 3:1. The purpose of this study was to uncover some of the factors that influenced five Hispanic males' participation, or lack thereof, in AVID, and the ways in which those factors connected to their masculine identities. What the participants say about what influenced them to be involved, or not, in the program is reported. Some themes revealed in the interviews include how the participants' scholar identity is connected to their masculine identity, how they balance their "coolness" quotient with their desires to achieve academic success, how they depend on personal relationships and collaboration, and how their families and communities have influenced them. This information may lead to the development of strategies that will increase future representation of Hispanic males in similar programs.
Contributors
Glenn, Kathleen (Kathleen Denise) (Author) / Marsh, Josephine (Thesis advisor) / Barone, Thomas (Committee member) / Cohn, Sanford (Committee member) / Arizona State University (Publisher)
Created
2011
Description
Restaurants have a cumulative impact on the environment, economy, and society. The majority of restaurants are small-to-medium enterprises (SMEs). Review of sustainability and industry literature revealed that considering restaurants as businesses with sustainable development options is the most appropriate way to evaluate their sustainable practices or lack thereof. Sustainable development is the means by which a company progresses towards achieving an identified set of sustainability goals and harnesses competitive advantage. The purpose of this thesis is to identify barriers to implementing sustainable practices in restaurants, and explore ways that restaurateurs can incorporate sustainable business practices. Energy consumption, water use, waste production, and food throughput are the four sustainability indicators addressed in this thesis. Interviews were conducted with five Tempe, Arizona restaurants, two of which consider their operations to be sustainable, and three of which are traditional restaurants. Results show that for traditional restaurants, the primary barriers to implementing sustainable business practices are cost, lack of awareness, and space. For sustainability-marketed restaurants, the barriers included a lack of knowledge or legal concerns. The sustainability-marketed restaurants have energy-efficient equipment and locally source a majority of their food purchases. There is a marked difference between the two types of restaurants in perception of barriers to sustainable business practices. I created a matrix to identify whether each indicator metric was applicable and present at a particular restaurant, and the potential barriers to implementing sustainable practices in each of the four indicator areas. Restaurants can use the assessment matrix to compare their current practices with sustainable practices and find ways to implement new or enhance existing sustainable practices. Identifying the barriers from within restaurants increases our understanding of the reasons why sustainable practices are not automatically adopted by SMEs. The assessment matrix can help restaurants overcome barriers to achieving sustainability by highlighting how to incorporate sustainable business practices.
Contributors
Freeman, Emily McConnell (Author) / Eakin, Hallie (Thesis advisor) / Basile, George (Thesis advisor) / Williams, Eric D. (Committee member) / Arizona State University (Publisher)
Created
2011
Description
The historical study of sentence adverbs has, before now, been based mostly on models that emphasize the pragmatic and discourse-based motivations of processes of grammaticalization. This dissertation breaks from such tradition by exploring diachronic adverb development through syntactic and morphological lenses. A generative, feature-based approach is used that incorporates the cartographic architecture developed by Cinque and combines it with a more phenomenological approach to both grammaticalization and lexicalization. Cinque's hierarchy of speech-act, evaluative, evidential, and epistemic adverbs is analyzed. It is determined (through corpus data) that these subcategories have grown in use primarily during the Modern English era, and particularly during the nineteenth and twentieth centuries. These four subcategories can be divided into two groups that are more general: speech-act adverbs, which arise from a (conditional) speech-act clause that undergoes ellipsis, and the other three types, which all arise from copula clauses. Each of these two groups is considered, and different methods of reanalysis by speakers are proposed for each. In addition, a revised model for categorizing adverbs is proposed. This model is based on morphological lexicalization (or univerbation) processes, thus accounting for the wide variety of adverbial source materials. Such lexicalization offers a pattern for sentence adverbial formation. Finally, Standard Chinese adverbials are briefly examined, with results indicating that they show very similar signs of lexicalization (within the limits of the writing system).
Contributors
Berry, James Andrew (Author) / Gelderen, Elly van (Thesis advisor) / Adams, Karen (Committee member) / Mailhammer, Robert (Committee member) / Arizona State University (Publisher)
Created
2011
Description
Most of challenges facing today's government cannot be resolved without collaborative efforts from multiple non-state stakeholders, organizations, and active participation from citizens. Collaborative governance has become an important form of management practice. Yet the success of this inclusive management approach depends on whether government agencies and all other involved parties can collectively deliberate and work toward the shared goals. This dissertation examines whether information technology (IT) tools and prior cooperative interactions can be used to facilitate the collaboration process, and how IT tools and prior cooperative interactions can, if at all, get citizens and communities more engaged in collaborative governance. It focuses on the individual and small groups engaged in deliberating on a local community problem, which is water sustainability in the Phoenix metropolitan area. Experiments were conducted to compare how people deliberate and interact with each other under different IT-facilitated deliberation environments and with different prehistory of interactions. The unique experimental site for this research is a designed deliberation space that can seat up to 25 participants surrounded by the immersive 260-degree seven-screen communal display. In total, 126 students from Arizona State University participated in the experiment. The experiment results show that the deliberation spaces can influence participants' engagement in the collaborative efforts toward collective goals. This dissertation demonstrates the great potential of well-designed IT-facilitated deliberation spaces for supporting policy deliberation and advancing collaborative governance. This dissertation provides practical suggestions for public managers and community leaders on how to design and develop the desired features of IT-facilitated interaction environments for face-to-face and computer-mediated online public deliberation activities. This dissertation also discusses lessons and strategies on how to build a stronger sense of community for promoting community-based efforts to achieve collective goals.
Contributors
Hu, Qian (Author) / Cayer, N. Joseph (Thesis advisor) / Lan, Zhiyong (Thesis advisor) / Johnston, Erik W., 1977- (Committee member) / Shangraw, Ralph (Committee member) / Arizona State University (Publisher)
Created
2011
Description
Parenting approaches that are firm yet warm (i.e., authoritative parenting) have been found to be robustly beneficial for mainstream White Americans youths, but do not demonstrate similarly consistent effects among Chinese Americans (CA) adolescents. Evidence suggests that CA adolescents interpret and experience parenting differently than their mainstream counterparts given differences in parenting values and child-rearing norms between traditional Chinese and mainstream American cultures. The current study tests the theory that prospective effects of parenting on psychological and academic functioning depends on adolescents' cultural frameworks for interpreting and understanding parenting. CA adolescents with values and expectations of parenting that are more consistent with mainstream American parenting norms were predicted to experience parenting similar to their White American counterparts (i.e., benefiting from a combination of parental strictness and warmth). In contrast, CA adolescents with parenting values and expectations more consistent with traditional Chinese parenting norms were predicted to experience parenting and its effects on academic and psychological outcomes differently than patterns documented in the mainstream literature. This study was conducted with a sample of Chinese American 9th graders (N = 500) from the Multicultural Family Adolescent Study. Latent Class Analysis (LCA), a person-centered approach to modeling CA adolescents' cultural frameworks for interpreting parenting, was employed using a combination of demographic variables (e.g., nativity, language use at home, mother's length of stay in the U.S.) and measures of parenting values and expectations (e.g., parental respect, ideal strictness & laxness). The study then examined whether prospective effects of parenting behaviors (strict control, warmth, and their interaction effect) on adolescent adjustment (internalizing and externalizing symptoms, substance use, and GPA) were moderated by latent class membership. The optimal LCA solution identified five distinct cultural frameworks for understanding parenting. Findings generally supported the idea that effects of parenting on CA adolescent adjustment depend on adolescents' cultural framework for parenting. The classic authoritative parenting effect (high strictness and warmth leads to positive outcomes) was found for the two most acculturated groups of adolescents. However, only one of these groups overtly endorsed mainstream American parenting values.
Contributors
Liu, Freda Fangfang (Author) / Gonzales, Nancy A. (Thesis advisor) / Tein, Jenn-Yun (Committee member) / Yoo, Hyung Chol (Committee member) / Barrera, Manuel (Committee member) / Arizona State University (Publisher)
Created
2011