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. ^

High energy three -body breakup of three -nucleon systems

The main goal of this dissertation was to study two- and three-nucleon Short Range Correlations (SRCs) in high energy three-body breakup of 3He nucleus in 3He(e, e'NN) N reaction. SRCs are characterized by quantum fluctuations in nuclei during which constituent nucleons partially overlap with each other. ^ A theoretical framework is developed within the Generalized Eikonal Approximation (GEA) which upgrades existing medium-energy methods that are inapplicable for high momentum and energy transfer reactions. High momentum and energy transfer is required to provide sufficient resolution for probing SRCs. GEA is a covariant theory which is formulated through the effective Feynman diagrammatic rules. It allows self-consistent calculation of single and double re-scatterings amplitudes which are present in three-body breakup processes. The calculations were carried out in detail and the analytical result for the differential cross section of 3He(e, e'NN)N reaction was derived in a form applicable for programming and numerical calculations. The corresponding computer code has been developed and the results of computation were compared to the published experimental data, showing satisfactory agreement for a wide range of values of missing momenta. ^ In addition to the high energy approximation this study exploited the exclusive nature of the process under investigation to gain more information about the SRCs. The description of the exclusive 3He( e, e'NN)N reaction has been done using the formalism of the nuclear decay function, which is a practically unexplored quantity and is related to the conventional spectral function through the integration of the phase space of the recoil nucleons. Detailed investigation showed that the decay function clearly exhibits the main features of two- and three-nucleon correlations. Four highly practical types of SRCs in 3He nucleus were discussed in great detail for different orders of the final state re-interactions using the decay function as an unique identifying tool. ^ The overall conclusion in this dissertation suggests that the investigation of the decay function opens up a completely new venue in studies of short range nuclear properties. ^

High energy three-body breakup of three-nucleon systems

The main goal of this dissertation was to study two- and three-nucleon Short Range Correlations (SRCs) in high energy three-body breakup of 3He nucleus in 3He(e, e'NN)N reaction. SRCs are characterized by quantum fluctuations in nuclei during which constituent nucleons partially overlap with each other. A theoretical framework is developed within the Generalized Eikonal Approximation (GEA) which upgrades existing medium-energy methods that are inapplicable for high momentum and energy transfer reactions. High momentum and energy transfer is required to provide sufficient resolution for probing SRCs. GEA is a covariant theory which is formulated through the effective Feynman diagrammatic rules. It allows self-consistent calculation of single and double re-scatterings amplitudes which are present in three-body breakup processes. The calculations were carried out in detail and the analytical result for the differential cross section of 3He(e, e'NN)Nreaction was derived in a form applicable for programming and numerical calculations. The corresponding computer code has been developed and the results of computation were compared to the published experimental data, showing satisfactory agreement for a wide range of values of missing momenta. In addition to the high energy approximation this study exploited the exclusive nature of the process under investigation to gain more information about the SRCs. The description of the exclusive 3He(e, e'NN)N reaction has been done using the formalism of the nuclear decay function, which is a practically unexplored quantity and is related to the conventional spectral function through the integration of the phase space of the recoil nucleons. Detailed investigation showed that the decay function clearly exhibits the main features of two- and three-nucleon correlations. Four highly practical types of SRCs in 3He nucleus were discussed in great detail for different orders of the final state re-interactions using the decay function as an unique identifying tool. The overall conclusion in this dissertation suggests that the investigation of the decay function opens up a completely new venue in studies of short range nuclear properties.

Exclusive electrodisintegration of three-nucleon systems

The purpose of this research was to develop a theory of high-energy exclusive electrodisintegration of three-nucleon systems on the example of 3He(e, e'NN)N reaction with knocked-out nucleon in the final state. The scattering amplitudes and differential cross section of the reaction were calculated in details within the Generalized Eikonal Approximation(GEA). The manifestly covariant nature of Feynman diagrams derived in GEA allowed us to preserve both the relativistic dynamics and kinematics of the scattering while identifying the low momentum nuclear part of the amplitude with a nonrelativistic nuclear wave function. Numerical calculations of the residual system's total and relative momentum distribution were performed which show reasonable agreement with available experimental data. The theoretical framework of GEA, which was applied previously only for the case of two-body (deuteron) high energy break up reactions, has been practically implemented and shown to provide a valid description for more complex A = 3 systems.

Classes sociais e eleições presidenciais no Brasil contemporâneo (2002-2010)

This work aims to analyze, in terms of class, the social composition of the constituency of the presidential candidates of the Workers Party in 2002, 2006 and 2010 elections. Such research object is constructed from a preliminary critical debate with recent Brazilian electoral studies, especially the literature on the infl uence of social programs on voting and Singer’s formulations about the lulismo phenomenon. Incorporating advances and pointing out gaps in such research efforts, is formulated a roadmap for empirical research constituted of three key elements - the measure ment of the dimensions of class structure in Brazilian capitalism; the observation of material interests related to the constituents locations of such structure; the development of measures of association between the insertion in class groupings and indivi dual voting behavior. Based on the neo - Marxist approach of class analysis, especially as formulated by Wright, it is made an adaptation of the typology formulated by such approach (mainly developed by Santos to the Brazilian case) to the data available fro m databases of censuses of 2000 and 2010. This theoretical construct reveals that during the period considered for the analysis, the structure of class - relations in Brazil became more proletarized and consequently had a decrease of the dimensions of the de stitute class locations. In addition, it was found, in relation to the objective class interests, widespread increments of economic welfare that allowed advances in relation to the material conditions of the proletariat, without, however, incurring losses to the privileged class positions. Such changes in the structural sphere focused in various ways on the political arena. Based on an adaptation to electoral analysis of the concept of "class formation", also formulated by Wright, associated with the use of techniques of ecological inference (especially those proposed by King and associates), it was possible to draw up an overview of class voting in period studied. As main results, three general patterns of individual voting behavior, related to each of the three analyzed class groupings were identified - a contraposition against PT candidates, by voters in privileged class locations; the adhesion, recurring throughout the study period, of workers to Lula and Dilma Rousseff; a favorable electoral shift unde rtaken by economically deprived voters in favor of those candidatures in the 2006 election.

Provocative feature deletion: a syntactic model of agreement alternations in noun incorporation contexts

The relationship between noun incorporation (NI) and the agreement alternations that occur in such contexts (NI Transitivity Alternations) remains inadequately understood. Three interpretations of these alternations (Baker, Aranovich & Golluscio 2005; Mithun 1984; Rosen 1989) are shown to be undermined by foundational or mechanical issues. I propose a syntactic model, adopting Branigan's (2011) interpretation of NI as the result of “provocative” feature valuation, which triggers generation of a copy of the object that subsequently merges inside the verb. Provocation triggers a reflexive Refine operation that deletes duplicate features from chains, making them interpretable for Transfer. NI Transitivity Alternations result from variant deletion preferences exhibited during Refine. I argue that the NI contexts discussed (Generic NI, Partial NI and Double Object NI) result from different restrictions on phonetic and semantic identity in chain formation. This provides us with a consistent definition of NI Transitivity Alternations across contexts, as well as a new typology that distinguishes NI contexts, rather than incorporating languages.

Bulk sediment parameter of three sediment cores from permafrost lowlands, Alaska Arctic Coastal Plain

Arctic lowland landscapes have been modified by thermokarst lake processes throughout the Holocene. Thermokarst lakes form as a result of ice-rich permafrost degradation and they may expand over time through thermal and mechanical shoreline erosion. We studied proximal and distal sedimentary records from a thermokarst lake located on the Arctic Coastal Plain of northern Alaska to reconstruct the impact of catchment dynamics and morphology on the lacustrine depositional environment and to quantify carbon accumulation in thermokarst lake sediments. Short cores were collected for analysis of pollen, sedimentological and geochemical proxies. Radiocarbon and Pb/Cs dating, as well as extrapolation of measured historic lake expansion rates, were applied to estimate a minimum lake age of ~ 1,400 calendar years BP. The pollen record is in agreement with the young lake age as it does not include evidence of the "alder high" that occurred in the region ~ 4.0 cal ka BP. The lake most likely initiated from a remnant pond in a drained thermokarst lake basin (DTLB) and deepened rapidly as evidenced by accumulation of laminated sediments. Increasing oxygenation of the water column as shown by higher Fe/Ti and Fe/S ratios in the sediment indicate shifts in ice regime with increasing water depth. More recently, the sediment source changed as the thermokarst lake expanded through lateral permafrost degradation, alternating from redeposited DTLB sediments, to increased amounts of sediment from eroding, older upland deposits, followed by a more balanced combination of both DTLB and upland sources. The characterizing shifts in sediment sources and depositional regimes in expanding thermokarst lakes were therefore archived in the thermokarst lake sedimentary record. This study also highlights the potential for Arctic lakes to recycle old carbon from thawing permafrost and thermokarst processes.

Full of Hot Air? Three Examinations of Climate Change in the American Political Information Environment

Climate change is thought to be one of the most pressing environmental problems facing humanity. However, due in part to failures in political communication and how the issue has been historically defined in American politics, discussions of climate change remain gridlocked and polarized. In this dissertation, I explore how climate change has been historically constructed as a political issue, how conflicts between climate advocates and skeptics have been communicated, and what effects polarization has had on political communication, particularly on the communication of climate change to skeptical audiences. I use a variety of methodological tools to consider these questions, including evolutionary frame analysis, which uses textual data to show how issues are framed and constructed over time; Kullback-Leibler divergence content analysis, which allows for comparison of advocate and skeptical framing over time; and experimental framing methods to test how audiences react to and process different presentations of climate change. I identify six major portrayals of climate change from 1988 to 2012, but find that no single construction of the issue has dominated the public discourse defining the problem. In addition, the construction of climate change may be associated with changes in public political sentiment, such as greater pessimism about climate action when the electorate becomes more conservative. As the issue of climate change has become more polarized in American politics, one proposed causal pathway for the observed polarization is that advocate and skeptic framing of climate change focuses on different facets of the issue and ignores rival arguments, a practice known as “talking past.” However, I find no evidence of increased talking past in 25 years of popular newsmedia reporting on the issue, suggesting both that talking past has not driven public polarization or that polarization is occurring in venues outside of the mainstream public discourse, such as blogs. To examine how polarization affects political communication on climate change, I test the cognitive processing of a variety of messages and sources that promote action against climate change among Republican individuals. Rather than identifying frames that are powerful enough to overcome polarization, I find that Republicans exhibit telltale signs of motivated skepticism on the issue, that is, they reject framing that runs counter to their party line and political identity. This result suggests that polarization constrains political communication on polarized issues, overshadowing traditional message and source effects of framing and increasing the difficulty communicators experience in reaching skeptical audiences.

On the Regulation of Small Actors: Three Experimental Essays about Policies based on Voluntary Compliance and Decentralized Monitoring

Monitoring and enforcement are perhaps the biggest challenges in the design and implementation of environmental policies in developing countries where the actions of many small informal actors cause significant impacts on the ecosystem services and where the transaction costs for the state to regulate them could be enormous. This dissertation studies the potential of innovative institutions based on decentralized coordination and enforcement to induce better environmental outcomes. Such policies have in common that the state plays the role of providing the incentives for organization but the process of compliance happens through decentralized agreements, trust building, signaling and monitoring. I draw from the literatures in collective action, common-pool resources, game-theory and non-point source pollution to develop the instruments proposed here. To test the different conditions in which such policies could be implemented I designed two field-experiments that I conducted with small-scale gold miners in the Colombian Pacific and with users and providers of ecosystem services in the states of Veracruz, Quintana Roo and Yucatan in Mexico. This dissertation is organized in three essays.

The first essay, “Collective Incentives for Cleaner Small-Scale Gold Mining on the Frontier: Experimental Tests of Compliance with Group Incentives given Limited State Monitoring”, examines whether collective incentives, i.e. incentives provided to a group conditional on collective compliance, could “outsource” the required local monitoring, i.e. induce group interactions that extend the reach of the state that can observe only aggregate consequences in the context of small-scale gold mining. I employed a framed field-lab experiment in which the miners make decisions regarding mining intensity. The state sets a collective target for an environmental outcome, verifies compliance and provides a group reward for compliance which is split equally among members. Since the target set by the state transforms the situation into a coordination game, outcomes depend on expectations of what others will do. I conducted this experiment with 640 participants in a mining region of the Colombian Pacific and I examine different levels of policy severity and their ordering. The findings of the experiment suggest that such instruments can induce compliance but this regulation involves tradeoffs. For most severe targets – with rewards just above costs – raise gains if successful but can collapse rapidly and completely. In terms of group interactions, better outcomes are found when severity initially is lower suggesting learning.

The second essay, “Collective Compliance can be Efficient and Inequitable: Impacts of Leaders among Small-Scale Gold Miners in Colombia”, explores the channels through which communication help groups to coordinate in presence of collective incentives and whether the reached solutions are equitable or not. Also in the context of small-scale gold mining in the Colombian Pacific, I test the effect of communication in compliance with a collective environmental target. The results suggest that communication, as expected, helps to solve coordination challenges but still some groups reach agreements involving unequal outcomes. By examining the agreements that took place in each group, I observe that the main coordination mechanism was the presence of leaders that help other group members to clarify the situation. Interestingly, leaders not only helped groups to reach efficiency but also played a key role in equity by defining how the costs of compliance would be distributed among group members.

The third essay, “Creating Local PES Institutions and Increasing Impacts of PES in Mexico: A real-Time Watershed-Level Framed Field Experiment on Coordination and Conditionality”, considers the creation of a local payments for ecosystem services (PES) mechanism as an assurance game that requires the coordination between two groups of participants: upstream and downstream. Based on this assurance interaction, I explore the effect of allowing peer-sanctions on upstream behavior in the functioning of the mechanism. This field-lab experiment was implemented in three real cases of the Mexican Fondos Concurrentes (matching funds) program in the states of Veracruz, Quintana Roo and Yucatan, where 240 real users and 240 real providers of hydrological services were recruited and interacted with each other in real time. The experimental results suggest that initial trust-game behaviors align with participants’ perceptions and predicts baseline giving in assurance game. For upstream providers, i.e. those who get sanctioned, the threat and the use of sanctions increase contributions. Downstream users contribute less when offered the option to sanction – as if that option signal an uncooperative upstream – then the contributions rise in line with the complementarity in payments of the assurance game.

Radon 222 and Radium 226 measured on water bottle samples during POLARSTERN cruise ARK-XXVI/3 (TransArc)

Air-sea gas exchange plays a key role in the cycling of greenhouse and other biogeochemically important gases. Although air-sea gas transfer is expected to change as a consequence of the rapid decline in summer Arctic sea ice cover, little is known about the effect of sea ice cover on gas exchange fluxes, especially in the marginal ice zone. During the Polarstern expedition ARK-XXVI/3 (TransArc, August/September 2011) to the central Arctic Ocean, we compared 222Rn/226Ra ratios in the upper 50 m of 14 ice-covered and 4 ice-free stations. At three of the ice-free stations, we find 222Rn-based gas transfer coefficients in good agreement with expectation based on published relationships between gas transfer and wind speed over open water when accounting for wind history from wind reanalysis data. We hypothesize that the low gas transfer rate at the fourth station results from reduced fetch due to the proximity of the ice edge, or lateral exchange across the front at the ice edge by restratification. No significant radon deficit could be observed at the ice-covered stations. At these stations, the average gas transfer velocity was less than 0.1 m/d (97.5% confidence), compared to 0.5-2.2 m/d expected for open water. Our results show that air-sea gas exchange in an ice-covered ocean is reduced by at least an order of magnitude compared to open water. In contrast to previous studies, we show that in partially ice-covered regions, gas exchange is lower than expected based on a linear scaling to percent ice cover.

Evaluation of semi-passive treatment technologies for septic lagoon capacity expansion

In Canada, increases in rural development has led to a growing need to effectively manage the resulting municipal and city sewage without the addition of significant cost- and energy- expending infrastructure. Storring Septic Service Limited is a family-owned, licensed wastewater treatment facility located in eastern Ontario. It makes use of a passive waste stabilization pond system to treat and dispose of waste and wastewater in an environmentally responsible manner. Storring Septic, like many other similar small-scale wastewater treatment facilities across Canada, has the potential to act as a sustainable eco-engineered facility that municipalities and service providers could utilize to manage and dispose of their wastewater. However, it is of concern that the substantial inclusion of third party material could be detrimental to the stability and robustness of the pond system. In order to augment the capacity of the current facility, and ensure it remains a self-sustaining system with the capacity to safely accept septage from other sewage haulers, it was hypothesized that pond effluent treatment could be further enhanced through the incorporation of one of three different technology solutions, which would allow the reduction of wastewater quality parameters below existing regulatory effluent discharge limits put in place by Ontario’s Ministry of the Environment and Climate Change (MOECC). Two of these solutions make use of biofilm technologies in order to enhance the removal of wastewater parameters of interest, and the third utilizes the natural water filtration capabilities of zebra mussels. Pilot-scale testing investigated the effects of each of these technologies on treatment performance under both cold and warm weather operation. This research aimed to understand the important mechanisms behind biological filtration methods in order to choose and optimize the best treatment strategy for full-scale testing and implementation. In doing so, a recommendation matrix was elaborated provided with the potential to be used as a universal operational strategy for wastewater treatment facilities located in environments of similar climate and ecology.

Sandcastles of hope? Civil society organizations and the working conditions of migrant farmworkers in North America

This research explores whether civil society organizations (CSOs) can contribute to more effectively regulating the working conditions of temporary migrant farmworkers in North America. This dissertation unfolds in five parts. The first part of the dissertation sets out the background context. The context includes the political economy of agriculture and temporary migrant labour more broadly. It also includes the political economy of the legal regulations that govern immigration and work relations. The second part of the research builds an analytical model for studying the operation of CSOs active in working with the migrant farmworker population. The purpose of the analytical framework is to make sense of real-world examples by providing categories for analysis and a means to get at the channels of influence that CSOs utilize to achieve their aims. To this end, the model incorporates the insights from three significant bodies of literature—regulatory studies, labour studies, and economic sociology. The third part of the dissertation suggests some key strategic issues that CSOs should consider when intervening to assist migrant farmworkers, and also proposes a series of hypotheses about how CSOs can participate in the regulatory process. The fourth part probes and extends these hypotheses by empirically investigating the operation of three CSOs that are currently active in assisting migrant farm workers in North America: the Agricultural Workers Alliance (Canada), Global Workers’ Justice Alliance (USA), and the Coalition of Immokalee Workers (USA). The fifth and final part draws together lessons from the empirical work and concluded that CSOs can fill gaps left by the waning power of actors, such as trade unions and labour inspectorates, as well as act in ways that these traditional actors can not.

Three Essays on Economic Development in the Natural Resources Sector

This thesis examines two ongoing development projects that received financial support from international development organizations, and an alternative mining tax proposed by the academia. Chapter 2 explores the impact of commoditization of coffee on its export price in Ethiopia. The first part of the chapter traces how the Ethiopian’s current coffee trade system and commoditization come to be. Using regression analysis, the second part tests and confirms the hypothesis that commoditization has led to a reduction in coffee export price. Chapter 3 conducts a cost-benefit analysis on a controversial, liquefied natural gas export project in Peru that sought to export one-third of the country’s proven natural gas reserves. While the country can receive royalty and corporate income tax in the short and medium term, these benefits are dwarfed by the future costs of paying for alternative energy after gas depletion. The conclusion is robust for a variety of future energy-price and energy-demand scenarios. Chapter 4 quantifies through simulation the economic distortions of two common mining taxes, the royalty and ad-valorem tax, vis-à-vis the resource rent tax. The latter is put forward as a better mining tax instrument on account of its non-distortionary nature. The rent tax, however, necessitates additional administrative burdens and induces tax-avoidance behavior, both leading to a net loss of tax revenue. By quantifying the distortions of royalty and the ad-valorem tax, one can establish the maximum loss that can be incurred by the rent tax. Simulation results indicate that the distortion of the ad-valorem tax is quite modest. If implemented, the rent tax is likely to result in a greater loss. While the subject matters may appear diverse, they are united by one theme. These initiatives were endorsed and supported by authorities and development agencies in the aim of furthering economic development and efficiency, but they are unlikely to fulfill the goal. Lessons for international development can be learnt from successful stories as well as from unsuccessful ones.

Challenges, Strengths and Opportunities Related to Implementing Comprehensive Evidence-Based Guidelines on Breast Cancer Survivorship Care by Primary Care Physicians and Nurse Practitioners in Southeastern Ontario

Background Many breast cancer survivors continue to have a broad range of physical and psychosocial problems after breast cancer treatment. As cancer centres move forward with earlier discharge of stable breast cancer survivors to primary care follow-up it is important that comprehensive evidence-based breast cancer survivorship care is implemented to effectively address these needs. Research suggests primary care providers are willing to provide breast cancer survivorship care but many lack the knowledge and confidence to provide evidence-based care. Purpose The overall purpose of this thesis was to determine the challenges, strengths and opportunities related to implementing comprehensive evidence-based breast cancer survivorship guidelines by primary care physicians and nurse practitioners in southeastern Ontario. Methods This mixed-methods research was conducted in three phases: (1) synthesis and appraisal of clinical practice guidelines relevant to provision of breast cancer survivorship care within the primary care practice setting; (2) a brief quantitative survey of primary care providers to determine actual practices related to provision of evidence-based breast cancer survivorship care; and (3) individual interviews with primary care providers about the challenges, strengths and opportunities related to provision of comprehensive evidence-based breast cancer survivorship care. Results and Conclusions In the first phase, a comprehensive clinical practice framework was created to guide provision of breast cancer survivorship care and consisted of a one-page checklist outlining breast cancer survivorship issues relevant to primary care, a three-page summary of key recommendations, and a one-page list of guideline sources. The second phase identified several knowledge and practice gaps, and it was determined that guideline implementation rates were higher for recommendations related to prevention and surveillance aspects of survivorship care and lowest related to screening for and management of long-term effects. The third phase identified three major challenges to providing breast cancer survivorship care: inconsistent educational preparation, provider anxieties, and primary care burden; and three major strengths or opportunities to facilitate implementation of survivorship care guidelines: tools and technology, empowering survivors, and optimizing nursing roles. A better understanding of these challenges, strengths and opportunities will inform development of targeted knowledge translation interventions to provide support and education to primary care providers.

Energizing the Oak Ridges Moraine? Analyzing the Policy Implications of Three Wind Energy Developments on the Oak Ridges Moraine and their Potential Impact on the Coordinated Land Use Planning Review through the Involvement of First Nations and Environmental Non-governmental Organizations

This research explores the policy implications of the approval of three wind energy projects on the Oak Ridges Moraine, and their impact on the Coordinated Land Use Planning Review process. Specifically, it focuses on the involvement of First Nations and environmental non-governmental organizations (ENGOs). This research was conducted through analyzing submissions to the Coordinated Land Use Planning Review, related legislation and policy, Environmental Review Tribunal hearing documents, and interviews with key informants. This research culminates in a number of recommendations to the Coordinated Review informed by the analysis.