Three-dimensional brain fiber tracking modeling in diffusion tensor imaging

This dissertation establishes the foundation for a new 3-D visual interface integrating Magnetic Resonance Imaging (MRI) to Diffusion Tensor Imaging (DTI). The need for such an interface is critical for understanding brain dynamics, and for providing more accurate diagnosis of key brain dysfunctions in terms of neuronal connectivity. ^ This work involved two research fronts: (1) the development of new image processing and visualization techniques in order to accurately establish relational positioning of neuronal fiber tracts and key landmarks in 3-D brain atlases, and (2) the obligation to address the computational requirements such that the processing time is within the practical bounds of clinical settings. The system was evaluated using data from thirty patients and volunteers with the Brain Institute at Miami Children's Hospital. ^ Innovative visualization mechanisms allow for the first time white matter fiber tracts to be displayed alongside key anatomical structures within accurately registered 3-D semi-transparent images of the brain. ^ The segmentation algorithm is based on the calculation of mathematically-tuned thresholds and region-detection modules. The uniqueness of the algorithm is in its ability to perform fast and accurate segmentation of the ventricles. In contrast to the manual selection of the ventricles, which averaged over 12 minutes, the segmentation algorithm averaged less than 10 seconds in its execution. ^ The registration algorithm established searches and compares MR with DT images of the same subject, where derived correlation measures quantify the resulting accuracy. Overall, the images were 27% more correlated after registration, while an average of 1.5 seconds is all it took to execute the processes of registration, interpolation, and re-slicing of the images all at the same time and in all the given dimensions. ^ This interface was fully embedded into a fiber-tracking software system in order to establish an optimal research environment. This highly integrated 3-D visualization system reached a practical level that makes it ready for clinical deployment. ^

Perceptions of underprepared community college students regarding their educational achievement

The purpose of this study was to understand the perceptions of underprepared college students who had participated in learning communities and who persisted to complete developmental classes and earned at least 30 college-level credit hours to graduate and the perceptions of their peers who had dropped out of college. The theories posed by Tinto, Astin, and Freire formed the framework for this case study. The 22 participants were graduates or transfer students now attending a public university, currently-enrolled sophomores, and students no longer enrolled at the time of the study. Semi-structured individual interviews and a group interview provided narrative data which were transcribed, coded, and analyzed to gain insights into the experiences and perspectives of the participants. The group interview provided a form of member checking to increase accuracy in interpreting themes. A peer reviewer provided feedback on the researcher’s data analysis procedures. The analysis yielded four themes and 14 sub-themes which captured the essence of the participants’ experiences. The pre-college characteristics/traits theme described the students’ internal values and attributes acquired prior to college. The external college support/community influence theme described the encouragement to attend college the students received from family, friends, and high school teachers. The social involvement theme described the students’ participation in campus activities and their interactions with other members of the campus. The academic integration theme described students’ use of campus resources and their contacts with the faculty. The persisters reported strong family and peer support, a sense of responsibility, appreciation for dedicated and caring faculty, and a belief that an education can be a liberatory means to achieve their goals. The non-persisters did not report having the same sense of purpose, goal orientation, determination, obligation to meet family expectations, peer support, campus involvement, positive faculty experiences, and time management skills. The researcher offers an emerging model for understanding factors associated with persistence and three recommendations for enhancing the academic experience of underprepared college students: (a) include a critical pedagogy perspective in coursework where possible, (b) integrate co-curricular activities with the academic disciplines, and (c) increase student-faculty interaction.

Secondary school inclusion rates: The relationship between the training and beliefs of school site principals and the implementation of inclusion

Programs require strong support and guidance from those in leadership positions to ensure proper implementation (Fullen, 2001). Consequently, school site principals must rely on the training they have received to support them in making appropriate decisions. It is the school site principal’s leadership that is pivotal in the success of students with disabilities (DiPaola & Walther-Thomas, 2003; Monteith, 2000). In fact, the principal has a moral obligation to provide an environment that supports social justice in schools (Grogan & Andrews, 2002). The inclusion of students with disabilities does just that—it ensures that these students are not segregated to a “separate but equal” education. This study utilized a participant survey to collect data on principals’ beliefs and training in special education. This information was compared to the percentage of time students with disabilities spent with their non-disabled peers in the principals’ respective schools. An analysis was conducted to identify if a linear relationship exists between the selected variables and the inclusion percentages. Open-ended questions were included in the original survey which allowed for a thematic analysis of the responses. These responses were utilized to allow participants to further express their thoughts on the identified variables. Results indicated that there were no statistically significant relationships identified between the beliefs and training of secondary school site principals and the percentage of time that their students in special education spend with their non-disabled peers. Although the original research questions were not supported, further post hoc analysis indicated that the results obtained did support that the principals believed inclusion had a social benefit to students. Additional investigation into the academic benefits of inclusion is still needed. In addition, principals who indicated that they had some type of training in special education indicated a higher percentage that the individual student should be the focal point when making placement decisions. These results support the need for further research in the area of principal preparation programs and their relationships to the daily practice of school site principals.

An analysis of the factors that influence regional economic development cooperation

This dissertation is a comparative case study of regional cooperation in the field of economic development. In the 21st century global economy, proponents of regionalism have put forth fresh arguments for collective action. A regional approach to economic development activity presents a classic social dilemma: How can local officials collectively improve the economic prospects of a region, and remain autonomous to act in the best interest of the local community? This research examines the role of social capital in overcoming this social dilemma. ^ Three (3) comparable Metropolitan Statistical Areas (MSAs) form the empirical basis of this research. The Houston MSA, the Atlanta MSA and the Miami MSA present distinct variations of regionalized economic development activity. This dissertation seeks to explain this disparity in the dependent variable. The hypothesis is that accrued social capital is crucial to obtaining economic development cooperative agreements.^ This qualitative research utilized secondary demographic and economic databases, survey instruments, interviews, field observations, and a review of legislative and administrative decisions to formulate a clear understanding of the factors influencing the current state of regional economic development cooperation within each region. The study concludes that the legislative and executive decisions of state government exert inordinate influence on the capacity of local officials to cooperate regionally for economic development purposes.^

Cultural perceptions of space and place in the South Florida *environment

Public opinion polls in the United States reveal that a great majority of Americans are aware and show concern about ecological issues and the need to preserve natural areas. In South Florida, natural resources have been subjected to enormous strain as the pressure to accommodate a growing population has led to rapid development. Suburbs have been built on areas that were once natural wetlands and farmlands, and the impact today shows a landscape where natural places have all but disappeared. This dissertation examines the intersection between the perceptions that individuals living in the South Florida region have with respect to the natural environment and local ecological problems with where their relationship to nature takes place. ^ The research is based upon both quantitative and qualitative data. The principal methodology used in this research is the ethnographic method, which employed the data gathering techniques of in-depth interviewing and participant observation. The objective of the qualitative portion of the study was to determine how people perceive and relate to their immediate environment. The quantitative portion of the study employed telephone survey data from the FIU/Florida Poll 2000. Data collected through this survey provided the basis to statistically test responses to the research questions. ^ The findings show that people in South Florida have a general idea of the relationship between the human population and the environment but very little knowledge of how they individually affect each other. The experience of private places and public spaces in everyday life permits people to compartmentalize cultural values and understandings of the natural world in separate cognitive schemas. The appreciation of the natural world has almost no connection to their personal sense of obligation to preserve the environment. That obligation is only felt in their home space even though the South Florida environment overall struggles desperately with water shortages, land encroachment, and a rapidly expanding human population whose activities continuously aggravate an already delicate natural balance. ^

Fuzzy Modeling and Control Based Virtual Machine Resource Management

Virtual machines (VMs) are powerful platforms for building agile datacenters and emerging cloud systems. However, resource management for a VM-based system is still a challenging task. First, the complexity of application workloads as well as the interference among competing workloads makes it difficult to understand their VMs’ resource demands for meeting their Quality of Service (QoS) targets; Second, the dynamics in the applications and system makes it also difficult to maintain the desired QoS target while the environment changes; Third, the transparency of virtualization presents a hurdle for guest-layer application and host-layer VM scheduler to cooperate and improve application QoS and system efficiency. This dissertation proposes to address the above challenges through fuzzy modeling and control theory based VM resource management. First, a fuzzy-logic-based nonlinear modeling approach is proposed to accurately capture a VM’s complex demands of multiple types of resources automatically online based on the observed workload and resource usages. Second, to enable fast adaption for resource management, the fuzzy modeling approach is integrated with a predictive-control-based controller to form a new Fuzzy Modeling Predictive Control (FMPC) approach which can quickly track the applications’ QoS targets and optimize the resource allocations under dynamic changes in the system. Finally, to address the limitations of black-box-based resource management solutions, a cross-layer optimization approach is proposed to enable cooperation between a VM’s host and guest layers and further improve the application QoS and resource usage efficiency. The above proposed approaches are prototyped and evaluated on a Xen-based virtualized system and evaluated with representative benchmarks including TPC-H, RUBiS, and TerraFly. The results demonstrate that the fuzzy-modeling-based approach improves the accuracy in resource prediction by up to 31.4% compared to conventional regression approaches. The FMPC approach substantially outperforms the traditional linear-model-based predictive control approach in meeting application QoS targets for an oversubscribed system. It is able to manage dynamic VM resource allocations and migrations for over 100 concurrent VMs across multiple hosts with good efficiency. Finally, the cross-layer optimization approach further improves the performance of a virtualized application by up to 40% when the resources are contended by dynamic workloads.

Perceptions of Underprepared Community College Students regarding their Educational Achievement

The purpose of this study was to understand the perceptions of underprepared college students who had participated in learning communities and who persisted to complete developmental classes and earned at least 30 college-level credit hours to graduate and the perceptions of their peers who had dropped out of college. The theories posed by Tinto, Astin, and Freire formed the framework for this case study. The 22 participants were graduates or transfer students now attending a public university, currently-enrolled sophomores, and students no longer enrolled at the time of the study. Semi-structured individual interviews and a group interview provided narrative data which were transcribed, coded, and analyzed to gain insights into the experiences and perspectives of the participants. The group interview provided a form of member checking to increase accuracy in interpreting themes. A peer reviewer provided feedback on the researcher’s data analysis procedures. The analysis yielded four themes and 14 sub-themes which captured the essence of the participants’ experiences. The pre-college characteristics/traits theme described the students’ internal values and attributes acquired prior to college. The external college support/community influence theme described the encouragement to attend college the students received from family, friends, and high school teachers. The social involvement theme described the students’ participation in campus activities and their interactions with other members of the campus. The academic integration theme described students’ use of campus resources and their contacts with the faculty. The persisters reported strong family and peer support, a sense of responsibility, appreciation for dedicated and caring faculty, and a belief that an education can be a liberatory means to achieve their goals. The non-persisters did not report having the same sense of purpose, goal orientation, determination, obligation to meet family expectations, peer support, campus involvement, positive faculty experiences, and time management skills. The researcher offers an emerging model for understanding factors associated with persistence and three recommendations for enhancing the academic experience of underprepared college students: (a) include a critical pedagogy perspective in coursework where possible, (b) integrate co-curricular activities with the academic disciplines, and (c) increase student-faculty interaction.

An Analysis of the Factors that Influence Regional Economic Development Cooperation

This dissertation is a comparative case study of regional cooperation in the field of economic development. In the 21st century global economy, proponents of regionalism have put forth fresh arguments for collective action. A regional approach to economic development activity presents a classic social dilemma: How can local officials collectively improve the economic prospects of a region, and remain autonomous to act in the best interest of the local community? This research examines the role of social capital in overcoming this social dilemma. Three (3) comparable Metropolitan Statistical Areas (MSAs) form the empirical basis of this research. The Houston MSA, the Atlanta MSA and the Miami MSA present distinct variations of regionalized economic development activity. This dissertation seeks to explain this disparity in the dependent variable. The hypothesis is that accrued social capital is crucial to obtaining economic development cooperative agreements. This qualitative research utilized secondary demographic and economic databases, survey instruments, interviews, field observations, and a review of legislative and administrative decisions to formulate a clear understanding of the factors influencing the current state of regional economic development cooperation within each region. The study concludes that the legislative and executive decisions of state government exert inordinate influence on the capacity of local officials to cooperate regionally for economic development purposes.

Variables affecting government debt: A comparison of certificates of participation, tax -exempt revenue bonds and tax -exempt general obligation bonds

This dissertation analyzed and compared variables affecting interest rate and yield of certificates of participation, tax-exempt revenue bonds and tax-exempt general obligation bonds. The study employed qualitative and quantitative analysis methods. ^ Qualitative research methods included surveys, interviews and focus groups. The survey solicited debt load information from 67 Florida school districts (21 responded) and addressed the question which districts used certificates of participation and why. Eight individuals with experience dealing with all three debt instruments were interviewed. A follow-up focus group of six school district financial officers gathered additional data. Results from the qualitative methods revealed school districts used certificates of participation based on millage authority amount available relative to overall tax base. Also identified was the belief of a significant difference in certificates of participation costs and the other two debt instrument types. ^ The study's quantitative methods analyzed 1998 and 1999 initial issues of Moody's AAA rated certificates of participation, tax-exempt revenue bonds and tax-exempt general obligation bonds. Through an analysis of covariance (ANCOVA), the study examined interest rates and yields while controlling for the covariates of credit enhancement, issue size, and maturity date. The analysis identified no significant difference between interest rates of certificates of participation and tax-exempt general obligation bonds (p < 0.05). There was a significant difference between interest rates of tax-exempt revenue bonds and tax-exempt general obligation bonds. This study discerned no significant difference between yield on certificates of participation and tax-exempt general obligation bonds. It identified a difference in yield between both certificates of participation and tax-exempt general obligation bonds compared with tax-exempt revenue bonds. ^ The study found COPs to have lesser overall costs than RV bonds. COPs also have a quicker entry into the market resulting in construction cost savings. The study found policy implications such as investment portfolio limitations and public choice issues about using COPs as a mechanism to grow government. ^