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- Genre: Doctoral Dissertation
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Description
Sensitivity is a fundamental challenge for in vivo molecular magnetic resonance imaging (MRI). Here, I improve the sensitivity of metal nanoparticle contrast agents by strategically incorporating pure and doped metal oxides in the nanoparticle core, forming a soluble, monodisperse, contrast agent with adjustable T2 or T1 relaxivity (r2 or r1). I first developed a simplified technique to incorporate iron oxides in apoferritin to form "magnetoferritin" for nM-level detection with T2- and T2* weighting. I then explored whether the crystal could be chemically modified to form a particle with high r1. I first adsorbed Mn2+ ions to metal binding sites in the apoferritin pores. The strategic placement of metal ions near sites of water exchange and within the crystal oxide enhance r1, suggesting a mechanism for increasing relaxivity in porous nanoparticle agents. However, the Mn2+ addition was only possible when the particle was simultaneously filled with an iron oxide, resulting in a particle with a high r1 but also a high r2 and making them undetectable with conventional T1-weighting techniques. To solve this problem and decrease the particle r2 for more sensitive detection, I chemically doped the nanoparticles with tungsten to form a disordered W-Fe oxide composite in the apoferritin core. This configuration formed a particle with a r1 of 4,870mM-1s-1 and r2 of 9,076mM-1s-1. These relaxivities allowed the detection of concentrations ranging from 20nM - 400nM in vivo, both passively injected and targeted to the kidney glomerulus. I further developed an MRI acquisition technique to distinguish particles based on r2/r1, and show that three nanoparticles of similar size can be distinguished in vitro and in vivo with MRI. This work forms the basis for a new, highly flexible inorganic approach to design nanoparticle contrast agents for molecular MRI.
ContributorsClavijo Jordan, Maria Veronica (Author) / Bennett, Kevin M (Thesis advisor) / Kodibagkar, Vikram (Committee member) / Sherry, A Dean (Committee member) / Wang, Xiao (Committee member) / Yarger, Jeffery (Committee member) / Arizona State University (Publisher)
Created2012
Description
ABTRACT For decades the United States has tried to increase the number of students pursuing science, technology, engineering, and mathematics (STEM) education and careers. Educators and policy makers continue to seek strategies to increase the number of students in the STEM education pipeline. Public institutions of higher education are involved in this effort through education and public outreach (EPO) initiatives. Arizona State University opened its largest research facility, the new Interdisciplinary Science and Technology Building IV (ISTB4) in September, 2012. As the new home of the School of Earth & Space Exploration (SESE), ISTB4 was designed to serve the school's dedication to K-12 education and public outreach. This dissertation presents a menu of ideas for revamping the EPO program for SESE. Utilizing the Delphi method, I was able to clarify which ideas would be most supported, and those that would not, by a variety of important SESE stakeholders. The study revealed that consensus exists in areas related to staffing and expansion of free programming, whereas less consensus exist in the areas of fee-based programs. The following most promising ideas for improving the SESE's EPO effort were identified and will be presented to SESE's incoming director in July, 2013: (a) hire a full-time director, theater manager, and program coordinator; (b) establish a service-learning requirement obligating undergraduate SESE majors to serve as docent support for outreach programs; (c) obligate all EPO operations to advise, assist, and contribute to the development of curricula, activities, and exhibits; (d) perform a market and cost analysis of other informational education venues offering similar programming; (3) establish a schedule of fee-based planetarium and film offerings; and (f) create an ISTB4 centric, fee-based package of programs specifically correlated to K12 education standards that can be delivered as a fieldtrip experience.
ContributorsFisher, Richard D. (Author) / Clark, Christopher M. (Thesis advisor) / Kelley, Michael (Committee member) / Glasper, Rufus (Committee member) / Arizona State University (Publisher)
Created2013
Description
Virtual Patient Simulations (VPS) are web-based exercises involving simulated patients in virtual environments. This study investigates the utility of VPS for increasing medical student clinical reasoning skills, collaboration, and engagement. Many studies indicate that VPS provide medical students with essential practice in clinical decision making before they encounter real life patients. The utility of a recursive, inductive VPS for increasing clinical decision-making skills, collaboration, or engagement is unknown. Following a design-based methodology, VPS were implemented in two phases with two different cohorts of first year medical students: spring and fall of 2013. Participants were 108 medical students and six of their clinical faculty tutors. Students collaborated in teams of three to complete a series of virtual patient cases, submitting a ballpark diagnosis at the conclusion of each session. Student participants subsequently completed an electronic, 28-item Exit Survey. Finally, students participated in a randomized controlled trial comparing traditional (tutor-led) and VPS case instruction methods. This sequence of activities rendered quantitative and qualitative data that were triangulated during data analysis to increase the validity of findings. After practicing through four VPS cases, student triad teams selected accurate ballpark diagnosis 92 percent of the time. Pre-post test results revealed that PPT was significantly more effective than VPS after 20 minutes of instruction. PPT instruction resulted in significantly higher learning gains, but both modalities supported significant learning gains in clinical reasoning. Students collaborated well and held rich clinical discussions; the central phenomenon that emerged was "synthesizing evidence inductively to make clinical decisions." Using an inductive process, student teams collaborated to analyze patient data, and in nearly all instances successfully solved the case, while remaining cognitively engaged. This is the first design-based study regarding virtual patient simulation, reporting iterative phases of implementation and design improvement, culminating in local theories (petite generalizations) about VPS design. A thick, rich description of environment, process, and findings may benefit other researchers and institutions in designing and implementing effective VPS.
ContributorsMcCoy, Lise (Author) / Wetzel, Keith (Thesis advisor) / Ewbank, Ann (Thesis advisor) / Simon, Harvey (Committee member) / Arizona State University (Publisher)
Created2014
Description
Advances in implantable MEMS technology has made possible adaptive micro-robotic implants that can track and record from single neurons in the brain. Development of autonomous neural interfaces opens up exciting possibilities of micro-robots performing standard electrophysiological techniques that would previously take researchers several hundred hours to train and achieve the desired skill level. It would result in more reliable and adaptive neural interfaces that could record optimal neural activity 24/7 with high fidelity signals, high yield and increased throughput. The main contribution here is validating adaptive strategies to overcome challenges in autonomous navigation of microelectrodes inside the brain. The following issues pose significant challenges as brain tissue is both functionally and structurally dynamic: a) time varying mechanical properties of the brain tissue-microelectrode interface due to the hyperelastic, viscoelastic nature of brain tissue b) non-stationarities in the neural signal caused by mechanical and physiological events in the interface and c) the lack of visual feedback of microelectrode position in brain tissue. A closed loop control algorithm is proposed here for autonomous navigation of microelectrodes in brain tissue while optimizing the signal-to-noise ratio of multi-unit neural recordings. The algorithm incorporates a quantitative understanding of constitutive mechanical properties of soft viscoelastic tissue like the brain and is guided by models that predict stresses developed in brain tissue during movement of the microelectrode. An optimal movement strategy is developed that achieves precise positioning of microelectrodes in the brain by minimizing the stresses developed in the surrounding tissue during navigation and maximizing the speed of movement. Results of testing the closed-loop control paradigm in short-term rodent experiments validated that it was possible to achieve a consistently high quality SNR throughout the duration of the experiment. At the systems level, new generation of MEMS actuators for movable microelectrode array are characterized and the MEMS device operation parameters are optimized for improved performance and reliability. Further, recommendations for packaging to minimize the form factor of the implant; design of device mounting and implantation techniques of MEMS microelectrode array to enhance the longevity of the implant are also included in a top-down approach to achieve a reliable brain interface.
ContributorsAnand, Sindhu (Author) / Muthuswamy, Jitendran (Thesis advisor) / Tillery, Stephen H (Committee member) / Buneo, Christopher (Committee member) / Abbas, James (Committee member) / Tsakalis, Konstantinos (Committee member) / Arizona State University (Publisher)
Created2013
Description
This study examined the processes of academic advisement in a school-centric university environment utilizing the O'Banion Model of Academic Advising (1972) as a baseline for theoretical comparison. The primary research question sought to explore if the O'Banion Model of Academic Advising, a dominant theory of advisement processes, was still representative of and present in contemporary advisement. A qualitative case study methodology was utilized to explore the lived experiences of professional staff academic advisors in the academic advisement process. Eleven professional staff advisors were interviewed for up to 90 minutes each about their lived experience in providing academic advisement services. A structured series of questions were asked about the academic advisors' experiences with the process and their daily advisement activities. The participants were asked how the vision, mission, philosophies, and structures of the institution impacted their role and responsibilities in the advisement process. Mixed results were found over the presence of the O'Banion Model in contemporary advisement. The results revealed significant additional workloads, unique structures, and complex roles as a result of the institution's school-centric philosophy. Role ambiguity and confusion over responsibility for the advisement process were found.
ContributorsDickson, Thomas (Author) / Wilkinson, Christine Kajikawa (Thesis advisor) / Avants, Lowell (Committee member) / Sullivan, Linda (Committee member) / Arizona State University (Publisher)
Created2014
Description
The basal ganglia are four sub-cortical nuclei associated with motor control and reward learning. They are part of numerous larger mostly segregated loops where the basal ganglia receive inputs from specific regions of cortex. Converging on these inputs are dopaminergic neurons that alter their firing based on received and/or predicted rewarding outcomes of a behavior. The basal ganglia's output feeds through the thalamus back to the areas of the cortex where the loop originated. Understanding the dynamic interactions between the various parts of these loops is critical to understanding the basal ganglia's role in motor control and reward based learning. This work developed several experimental techniques that can be applied to further study basal ganglia function. The first technique used micro-volume injections of low concentration muscimol to decrease the firing rates of recorded neurons in a limited area of cortex in rats. Afterwards, an artificial cerebrospinal fluid flush was injected to rapidly eliminate the muscimol's effects. This technique was able to contain the effects of muscimol to approximately a 1 mm radius volume and limited the duration of the drug effect to less than one hour. This technique could be used to temporarily perturb a small portion of the loops involving the basal ganglia and then observe how these effects propagate in other connected regions. The second part applied self-organizing maps (SOM) to find temporal patterns in neural firing rate that are independent of behavior. The distribution of detected patterns frequency on these maps can then be used to determine if changes in neural activity are occurring over time. The final technique focused on the role of the basal ganglia in reward learning. A new conditioning technique was created to increase the occurrence of selected patterns of neural activity without utilizing any external reward or behavior. A pattern of neural activity in the cortex of rats was selected using an SOM. The pattern was then reinforced by being paired with electrical stimulation of the medial forebrain bundle triggering dopamine release in the basal ganglia. Ultimately, this technique proved unsuccessful possibly due to poor selection of the patterns being reinforced.
ContributorsBaldwin, Nathan Aaron (Author) / Helms Tillery, Stephen I (Thesis advisor) / Castaneda, Edward (Committee member) / Buneo, Christopher A (Committee member) / Muthuswamy, Jitendran (Committee member) / Si, Jennie (Committee member) / Arizona State University (Publisher)
Created2014
Description
Every year, potential graduate students hunt through websites and promotional materials searching for the perfect program to fit their needs. The search requires time and patience, especially for those future scholars who seek a doctoral program in Education Policy Studies (EPS) with a focus on interacting with the policymaking process. The primary objective of this project was to explore the promotional materials of EPS doctoral programs in order to better understand how these programs promote formalized training for students to engage with education policy and the policymaking process. I selected the top 10 EPS programs in the nation along with my own institution (Arizona State University) as the sample for this study. By reviewing their websites, I found that programs provide a comparable training description for similar careers as well as upholding similar goals in the subfield of EPS. Ultimately, the program materials revealed that while these programs advertise significant formalized training in research methods and scholarly pursuits, opportunities to actively engage with policymaking were missing from the materials. Instead, it is more likely that such opportunities occur in informal settings such as apprenticeships and working at research centers. This study provides a detailed discussion of how programs promote training opportunities to students, the types of careers that programs claim to prepare students for, and the important role that faculty projects and additional resources play in the student experience related to engagement with policy and the policymaking process.
ContributorsLong-Genovese, Stacey (Author) / Garcia, David R. (Thesis advisor) / Ott, Molly (Committee member) / Hinchey, Patricia (Committee member) / Arizona State University (Publisher)
Created2014
Description
ABSTRACT Counselors at a public community college who teach a first-year college success course to developmental education students do not have effective opportunities or a systematic method to develop their teaching practice. Moreover, like a majority of community college and university instructors, many counselors do not have formal training in instruction. Since the retention and persistence rates of developmental education students are low when compared to non-developmental education students, and the purpose of the college success course is to increase developmental education student success, it is imperative that instructors of the college success course are well-trained to provide high quality learning experiences. The researcher implemented the Lesson Study (LS) professional learning experience in order to increase the collaboration amongst counselors in their efforts to improve their teaching practice as well as improve the quality of the learning experience for developmental education students, consequently potentially improving their retention and persistence. The researcher facilitated a mixed-method study to explore how instructors made meaning of their teaching practice as well as what changes they made to their instructional practice while engaging in LS. The researcher utilized qualitative means to analyze the following data: (1) instructors' weekly reflective journals, (2) semi-structured interviews with instructors after each cycle of LS, (3) video recordings of LS debrief meetings, and (4) video recordings of LS planning meetings. The researcher utilized quantitative means to analyze the following data: (1) pre/post instructor surveys on self-efficacy, and (2) 1,235 student questionnaires regarding LS lessons and non-LS lessons. Analysis of the qualitative data demonstrated that how counselors made meaning of their LS experience seemed to correlate with positive features attributed to the practice of LS in the research literature such as increased collaboration and in-depth reflection as well as positive changes in instructional practices and an increased focus on learning from practice. In addition, analysis of the qualitative and quantitative data showed that lessons created through LS produced a higher quality learning experience for students than lessons that were not created through LS. Moreover, the analysis of the data showed an increase in instructors' efficacy for teaching.
ContributorsLucas, Miguel (Author) / Carlson, David L. (Thesis advisor) / Barnard, Wendy (Committee member) / Haas, Eric (Committee member) / Arizona State University (Publisher)
Created2014
Description
The purpose of the study is to explore the identity development and organizational culture of a student organization, the National Association of Latino Fraternal Organizations council (NALFO) by implementing a community of practice approach at a large, public university in southwestern United States. The objective is to construct a sustainable camaraderie among the existing Latino fraternal organizations at the university to influence leadership development, work toward a common vision, and a cohesive and systematic approach to collaboration, consequently transforming organizational culture. This study investigates the factors that contribute to and/or inhibit increased communication and collaboration and to describe the experiences of Latino fraternal members who are purposefully engaged in a community of practice. There are 57 fraternal organizations in five umbrella councils at the university, including predominately Caucasian, historically African American, Latino, and Multicultural groups, whose platforms are commonly leadership, scholarship, and philanthropy. This action research examines the experiences of six NALFO members individually and working as a community with the guidance of a mentor (the researcher). The researcher employs use of an anonymous initial and post electronic survey, a participant personal statement, an intentional and purposeful community of practice, a semi-structured individual interview, and focus groups to collect data. Findings suggest that length of membership and fraternal experience influence participant responses; however, the themes remain consistent. Building relationships, perception (by members and outsiders), identity development, organizational management, and challenging perspectives (from outside influences) are factors that influence the organizational culture of the organization. On the post electronic survey all participants indicate that the implementation of an intentional community of practice can benefit the organization by encouraging participation and increasing communication. While participants suggest activities for encouraging member engagement, they determine that actual participation would be dependent on individual motivation.
ContributorsHeredia, Anna-Maria (Author) / Rund, James (Thesis advisor) / Calleroz White, Mistalene (Thesis advisor) / Corey, Frederick (Committee member) / Arizona State University (Publisher)
Created2013
Description
Coronary heart disease (CHD) is the most prevalent cause of death worldwide. Atherosclerosis which is the condition of plaque buildup on the inside of the coronary artery wall is the main cause of CHD. Rupture of unstable atherosclerotic coronary plaque is known to be the cause of acute coronary syndrome. The composition of plaque is important for detection of plaque vulnerability. Due to prognostic importance of early stage identification, non-invasive assessment of plaque characterization is necessary. Computed tomography (CT) has emerged as a non-invasive alternative to coronary angiography. Recently, dual energy CT (DECT) coronary angiography has been performed clinically. DECT scanners use two different X-ray energies in order to determine the energy dependency of tissue attenuation values for each voxel. They generate virtual monochromatic energy images, as well as material basis pair images. The characterization of plaque components by DECT is still an active research topic since overlap between the CT attenuations measured in plaque components and contrast material shows that the single mean density might not be an appropriate measure for characterization. This dissertation proposes feature extraction, feature selection and learning strategies for supervised characterization of coronary atherosclerotic plaques. In my first study, I proposed an approach for calcium quantification in contrast-enhanced examinations of the coronary arteries, potentially eliminating the need for an extra non-contrast X-ray acquisition. The ambiguity of separation of calcium from contrast material was solved by using virtual non-contrast images. Additional attenuation data provided by DECT provides valuable information for separation of lipid from fibrous plaque since the change of their attenuation as the energy level changes is different. My second study proposed these as the input to supervised learners for a more precise classification of lipid and fibrous plaques. My last study aimed at automatic segmentation of coronary arteries characterizing plaque components and lumen on contrast enhanced monochromatic X-ray images. This required extraction of features from regions of interests. This study proposed feature extraction strategies and selection of important ones. The results show that supervised learning on the proposed features provides promising results for automatic characterization of coronary atherosclerotic plaques by DECT.
ContributorsYamak, Didem (Author) / Akay, Metin (Thesis advisor) / Muthuswamy, Jit (Committee member) / Akay, Yasemin (Committee member) / Pavlicek, William (Committee member) / Vernon, Brent (Committee member) / Arizona State University (Publisher)
Created2013