Matching Items (43,913)
Description
Although U.S. rates of college enrollment among 18-24 year olds have reached historic highs, rates of degree completion have not kept pace. This is especially evident at community colleges, where a disproportionate number of students from groups who, historically, have had low college-completion rates enroll. One way community colleges are attempting to address low completion rates is by implementing institutional interventions intended to increase opportunities for student engagement at their colleges. Utilizing logistic and linear regression analyses, this study focused on community college students, examining the association between participation in institutional support activities and student outcomes, while controlling for specific student characteristics known to impact student success in college. The sample included 746 first-time, full-time, degree-seeking students at a single community college located in the U.S. Southwest. Additional analyses were conducted for the 440 first-time, full-time, degree-seeking students in this sample who placed into at least one developmental education course. Findings indicate that significant associations exist between different types of participation in institutional interventions and various student outcomes: Academic advising was found to be related to increased rates of Fall to Spring and Fall to Fall persistence and, for developmental education students, participation in a student success course was found to be related to an increase in the proportion of course credit hours earned. The results of this study provide evidence that student participation in institutional-level support may relate to increased rates of college persistence and credit hour completion; however, additional inquiry is warranted to inform specific policy and program decision-making at the college and to determine if these findings are generalizable to populations outside of this college setting.
ContributorsBeckert, Kimberly Marrone (Author) / De Los Santos Jr., Alfredo G (Thesis advisor) / Thompson, Marilyn S (Thesis advisor) / Berliner, David C. (Committee member) / Arizona State University (Publisher)
Created2011
Description
A major goal of synthetic biology is to recapitulate emergent properties of life. Despite a significant body of work, a longstanding question that remains to be answered is how such a complex system arose? In this dissertation, synthetic nucleic acid molecules with alternative sugar-phosphate backbones were investigated as potential ancestors of DNA and RNA. Threose nucleic acid (TNA) is capable of forming stable helical structures with complementary strands of itself and RNA. This provides a plausible mechanism for genetic information transfer between TNA and RNA. Therefore TNA has been proposed as a potential RNA progenitor. Using molecular evolution, functional sequences were isolated from a pool of random TNA molecules. This implicates a possible chemical framework capable of crosstalk between TNA and RNA. Further, this shows that heredity and evolution are not limited to the natural genetic system based on ribofuranosyl nucleic acids. Another alternative genetic system, glycerol nucleic acid (GNA) undergoes intrasystem pairing with superior thermalstability compared to that of DNA. Inspired by this property, I demonstrated a minimal nanostructure composed of both left- and right-handed mirro image GNA. This work suggested that GNA could be useful as promising orthogonal material in structural DNA nanotechnology.
ContributorsZhang, Su (Author) / Chaut, John C (Thesis advisor) / Ghirlanda, Giovanna (Committee member) / Yan, Hao (Committee member) / Arizona State University (Publisher)
Created2011
Description
There are many lines of evidence for anisotropy at all scales in the explosions of core collapse supernovae, e.g. visual inspection of the images of resolved supernova remnants, polarization measurements, velocity profiles, "natal kicks" of neutron stars, or spectroscopic observations of different regions of remnants. Theoretical stability considerations and detailed numerical simulations have shown that Rayleigh-Taylor (RT) instabilities arise in the star after the explosion, which leads to the early fragmentation of parts of the ejecta. The clumps thus created are of interest to a variety of topics, one of them being the formation environment of the solar system. There is a high probability that the solar system formed in the vicinity of a massive star that, shortly after its formation, exploded as a core collapse supernova. As argued in this thesis as well as other works, a core collapse supernova generally is a good candidate for chemically enriching the forming solar system with material. As forming proto--planetary systems in general have a high probability of being contaminated with supernova material, a method was developed for detecting tracer elements indicative supernova contamination in proto--planetary systems.The degree of the anisotropy of the supernova explosion can have dramatic effects on the mode of delivery of that material to the solar system, or proto--planetary systems in general. Thus it is of particular interest to be able to predict the structure of the supernova ejecta. Numerical simulations of the explosions of core collapse supernovae were done in 3 dimensions in order to study the formation of structure. It is found that RT instabilities result in clumps in the He- and C+O rich regions in the exploding star that are overdense by 1-2 orders of magnitude. These clumps are potential candidates for enriching the solar system with material. In the course of the further evolution of the supernova remnant, these RT clumps are likely to evolve into ejecta knots of the type observed in the Cassiopeia A supernova remnant.
ContributorsEllinger, Carola I (Author) / Young, Patrick A (Thesis advisor) / Desch, Steven J (Committee member) / Timmes, Francis (Committee member) / Scannapieco, Evan (Committee member) / Lunardini, Cecilia (Committee member) / Arizona State University (Publisher)
Created2011
Description
Thermal interface materials (TIMs) are extensively used in thermal management applications especially in the microelectronics industry. With the advancement in microprocessors design and speed, the thermal management is becoming more complex. With these advancements in microelectronics, there have been parallel advancements in thermal interface materials. Given the vast number of available TIM types, selection of the material for each specific application is crucial. Most of the metrologies currently available on the market are designed to qualify TIMs between two perfectly flat surfaces, mimicking an ideal scenario. However, in realistic applications parallel surfaces may not be the case. In this study, a unique characterization method is proposed to address the need for TIMs characterization between non-parallel surfaces. Two different metrologies are custom-designed and built to measure the impact of tilt angle on the performance of TIMs. The first metrology, Angular TIM Tester, is based on the ASTM D5470 standard with flexibility to perform characterization of the sample under induced tilt angle of the rods. The second metrology, Bare Die Tilting Metrology, is designed to validate the performance of TIM under induced tilt angle between the bare die and the cooling solution in an "in-situ" package testing format. Several types of off-the-shelf thermal interface materials were tested and the results are outlined in the study. Data were collected using both metrologies for all selected materials. It was found that small tilt angles, up to 0.6°, have an impact on thermal resistance of all materials especially for in-situ testing. In addition, resistance change between 0° and the selected tilt angle was found to be in close agreement between the two metrologies for paste-based materials and phase-change material. However, a clear difference in the thermal performance of the tested materials was observed between the two metrologies for the gap filler materials.
ContributorsHarris, Enisa (Author) / Phelan, Patrick (Thesis advisor) / Calhoun, Ronald (Committee member) / Devasenathipathy, Shankar (Committee member) / Arizona State University (Publisher)
Created2011
Description
Accounts in the media often demonize teachers and misrepresent what is happening in schools. Meanwhile, teachers' voices are largely absent from the national and international debates on school reform. This dissertation privileges the voices of nine participating Kindergarten through second grade teachers from a variety of public schools, including affluent schools and schools receiving full and partial Title I funding. Through observations and interviews teachers shared their narratives of classroom joys and challenges while also describing how policy has affected these experiences. A preliminary discourse analysis of these narratives was performed, identifying narratives related to nodes of the activity system of schooling. Further discourse analysis of these identified narratives revealed how these teachers' classroom experiences position them within an activity system strongly influenced by tensions between maternal relationships and the patriarchal project of schooling. A critical feminist theoretical perspective is utilized to respond to these tensions and to describe possibilities for future studies in education and the future of education in general.
ContributorsGaches, Sonya (Author) / Swadener, Elizabeth B (Thesis advisor) / Sandlin, Jennifer (Committee member) / Gee, James (Committee member) / Arizona State University (Publisher)
Created2011
Description
As clarinet compositions created by Taiwanese composers have not been widely discussed and published in academia, this research paper examines three unaccompanied clarinet works by three Taiwanese composers: Ballade by Hsiao-Wen Tseng, Chin Thoughts III by Ling-Huei Tsai, and Pointe de Flame by Chia-Lin Pan, all commissioned by the author in 2007. This research also includes a compact disc with recordings of these works, aiming to document the creativity of Taiwanese composers. This research paper examines these three commissioned works by analyzing their overall musical styles, notations, formal structures, rhythmical and melodic materials, unconventional clarinet techniques as well as the influence of Chinese musical elements. The analysis reveals the distinctive characteristic of each piece. Moreover, the author provides composers' insights and performance guides to help interested readers practice these pieces. To further understand how the composers create these pieces by drawing upon different life experiences, the paper also includes information about their backgrounds, program notes, lists of compositions, and music examples for reference. The author found that collaborating with these composers helped to establish a closer composer-performer relationship in interpreting the music. It is hoped that this compact disc recording will help make Taiwanese composers' clarinet works more accessible to a wider audience. Moreover, this research paper hopes to generate more interest in performing and appreciating music composed by Taiwanese composers.
ContributorsChuang, Yenting (Author) / Spring, Robert (Thesis advisor) / Schuring, Martin (Committee member) / Campbell, Andrew (Committee member) / Jiang, Danwen (Committee member) / Hackbarth, Glenn (Committee member) / Arizona State University (Publisher)
Created2011
Description
ABSTRACT A hallmark of Arizona schools is the choice of parents in program and school for their child under the Open Enrollment laws. Among the choices for parents at some schools is Dual Language education, a form of enrichment wherein students learn the content of the Arizona State Standards through the medium of their primary language and a second language. The schools of this study use English and Spanish as the two languages. After 13 years of existence, changes in enrollment patterns have been noticed. Some parents whose older children attended Dual Language classes have chosen to dis-enroll their families from the program, so that their younger children are in English Only classes. At the same time that these trends in enrollment began, so too did strict enactment, enforcement, and monitoring of Arizona's Structured English Immersion program, the Department of Education's response to the voter approved Proposition 203--English for the Children--in November 2000. This study asks the following research question of de-selecting parents involved with Dual Language programs in Phoenix, Arizona: What are the rationale that influence parents to de-select Dual Language instruction in Arizona public schools in 2010 after having selected Dual Language for their older child(ren)? The study uses a Latino Critical Race Theory (LatCrit) Conceptual Framework to analyze interviews of 10 parents and 2 administrators from Dual Language programs in Phoenix, Arizona. There are three general findings of the study: 1) Parents sought asymmetrical measures of program design if their children were struggling in one language more than another, and chose to de-select when these asymmetrical measures were not enacted, 2) the de-selection process was generally not the result of family decision making, but rather reactionary to a situation, and 3) legislative mandates resulted in de-selection of the program. The LatCrit perspective showed most strongly in the third of these, wherein the de-selection was not necessarily a result of parent de-selection of the program, but rather the state's de-selection of willing participants in a language learning option. The hopes of the study are to hear the voices of parents who have to negotiate language policies and make programmatic choice decisions for their children. I also hope to provide information that Dual Language schools can use to understand the motivations and perspectives of the parents that will enable them to strengthen their programs and advocate for equality in opportunity for enrichment language programs for all children at their schools.
ContributorsRobert, Michael Anthony (Author) / Ovando, Carlos J (Thesis advisor) / Fischman, Gustavo E (Committee member) / Mccarty, Teresa L (Committee member) / Arizona State University (Publisher)
Created2011
Description
This dissertation presents a systematic study of the sorption mechanisms of hydrophobic silica aerogel (Cabot Nanogel®) granules for oil and volatile organic compounds (VOCs) in different phases. The performance of Nanogel for removing oil from laboratory synthetic oil-in-water emulsions and real oily wastewater, and VOCs from their aqueous solution, in both packed bed (PB) and inverse fluidized bed (IFB) modes was also investigated. The sorption mechanisms of VOCs in the vapor, pure liquid, and aqueous solution phases, free oil, emulsified oil, and oil from real wastewater on Nanogel were systematically studied via batch kinetics and equilibrium experiments. The VOC results show that the adsorption of vapor is very slow due to the extremely low thermal conductivity of Nanogel. The faster adsorption rates in the liquid and solution phases are controlled by the mass transport, either by capillary flow or by vapor diffusion/adsorption. The oil results show that Nanogel has a very high capacity for adsorption of pure oils. However, the rate for adsorption of oil from an oil-water emulsion on the Nanogel is 5-10 times slower than that for adsorption of pure oils or organics from their aqueous solutions. For an oil-water emulsion, the oil adsorption capacity decreases with an increasing proportion of the surfactant added. An even lower sorption capacity and a slower sorption rate were observed for a real oily wastewater sample due to the high stability and very small droplet size of the wastewater. The performance of Nanogel granules for removing emulsified oil, oil from real oily wastewater, and toluene at low concentrations in both PB and IFB modes was systematically investigated. The hydrodynamics characteristics of the Nanogel granules in an IFB were studied by measuring the pressure drop and bed expansion with superficial water velocity. The density of the Nanogel granules was calculated from the plateau pressure drop of the IFB. The oil/toluene removal efficiency and the capacity of the Nanogel granules in the PB or IFB were also measured experimentally and predicted by two models based on equilibrium and kinetic batch measurements of the Nanogel granules.
ContributorsWang, Ding (Author) / Lin, Jerry Y.S. (Thesis advisor) / Pfeffer, Robert (Thesis advisor) / Westerhoff, Paul (Committee member) / Nielsen, David (Committee member) / Lind, Mary Laura (Committee member) / Arizona State University (Publisher)
Created2011
Description
In 2005, the Navajo Sovereignty in Education Act was signed into law by the Navajo Nation. Like the No Child Left Behind Act, this Navajo Nation legislation was as much a policy statement as it was a law. It marked the first time that the Navajo Nation linked sovereignty with education by expressing its intent to control all education within its exterior boundaries. The objective of the law was to create a department of education that would resemble the states of Arizona, New Mexico, and Utah in which the Navajo Nation resides. Through their department of education, the Navajo Nation would operate the educational functions for its populace. This study looked at the implications and impact that perspectives of this law would have on public schools within Arizona from the perspective of five superintendents in Arizona public schools within the Navajo Nation were gained through open-ended interviews. It examined the legal, fiscal, and curricular issues through the prism of sovereignty. Through the process of interviews utilizing a set of guided questions in a semi-structured format, five superintendents in Arizona public schools within the Navajo Nation shared their perspectives. Analysis of the five interviews revealed curriculum, funding, jurisdictional, and fear or mistrust as problems the Navajo Nation will need to overcome if it is to begin full control of all aspects of education within its boundaries. There is a strong need for the Department of Dine' Education to educate public schools with regards to the Navajo Nation Sovereignty in Education Act of 2005. Administrators need more training in tribal governments. Like the constitution, the Navajo Sovereignty in Education Act will be interpreted differently by different people. But, without action, it will be ignored. Within the Act's pages are the hopes of the Navajo Nation and the dreams for our young Navajo students.
ContributorsRoessel, Karina A (Author) / Appleton, Nicholas (Thesis advisor) / Spencer, Dee Ann (Thesis advisor) / Wauneka, Jacquelyne (Committee member) / Arizona State University (Publisher)
Created2011
Description
The flow around a golf ball is studied using direct numerical simulation (DNS). An immersed boundary approach is adopted in which the incompressible Navier-Stokes equations are solved using a fractional step method on a structured, staggered grid in cylindrical coordinates. The boundary conditions on the surface are imposed using momentum forcing in the vicinity of the boundary. The flow solver is parallelized using a domain decomposition strategy and message passing interface (MPI), and exhibits linear scaling on as many as 500 processors. A laminar flow case is presented to verify the formal accuracy of the method. The immersed boundary approach is validated by comparison with computations of the flow over a smooth sphere. Simulations are performed at Reynolds numbers of 2.5 × 104 and 1.1 × 105 based on the diameter of the ball and the freestream speed and using grids comprised of more than 1.14 × 109 points. Flow visualizations reveal the location of separation, as well as the delay of complete detachment. Predictions of the aerodynamic forces at both Reynolds numbers are in reasonable agreement with measurements. Energy spectra of the velocity quantify the dominant frequencies of the flow near separation and in the wake. Time-averaged statistics reveal characteristic physical patterns in the flow as well as local trends within dimples. A mechanism of drag reduction due to the dimples is confirmed, and metrics for dimple optimization are proposed.
ContributorsSmith, Clinton E (Author) / Squires, Kyle D (Thesis advisor) / Balaras, Elias (Committee member) / Herrmann, Marcus (Committee member) / Adrian, Ronald (Committee member) / Stanzione, Daniel C (Committee member) / Calhoun, Ronald (Committee member) / Arizona State University (Publisher)
Created2011