title: Governing an Unknown Future: Discourses of Risk in the International Regulation of the Financial Services Sector

contributor:
Porter, Tony
Political Science

subject: international, financial, regulation, risk-based, future, governance,

abstract:
 International financial regulation has increasingly focused on 'risk-based' management over the last decade. In general, risk is a term embodied with the notion of an uncertain future and a belief that the use of rational and calculative practices can reveal, measure, and manage these potential futures. This dissertation argues that at the macro level financial governance is permeated with a tension between two overarching discourses of risk-risk as an economic necessity and risk as a danger or threat. These two macro-discourses influence and/or legitimize various courses of action in a general way that in some respects is similar to the role played by ideas in other approaches. However these macro-discourses do not only guide the regulatory actors involved. By drawing out the links between these discourses and the performative risk practices they constitute, this dissertation reveals how risk discourses operate in an ongoing way through the practical implementation of regulatory strategies, which implicitly or explicitly play one macro-discourse off the other. Moreover, the risk practices created, which include mundane, routine, and highly technical activities, work to construct the everyday performance offinancial governance and the identities of those actors included and excluded from the system.

 To examine this relationship, the dissertation looks at the international governance efforts of three financial areas: banking capital adequacy requirements, reinsurance and collective investment schemes. In the process, it reveals that the focus on risk in regulation creates some generalities across the realm of financial governance, but also that the micro-practices, identities and power produced in each arena are distinctive. It argues that by interrogating the macro-discursive constructions of risk and the practices and identities constituted through them, key tensions are revealed which, at least in part, explain the structure and goals of international financial regulation.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Characterizing And Quantifying Ecosystem Component CO2 Emissions From Different-Aged, Planted, Pine Forests

title: Component CO2 Emissions of Planted Pine Forests

contributor:
Arain, M. Altaf
Geography and Earth Sciences

subject: CO2, atmoshpere, climate change, global warming, environment, pollution, green, tree, sustainability, ecosystems, forests, respiration, Re, soil respiration, Rs, Re, climate, tree

abstract:
 The rapid increase of athropogenically-derived CO2 in the atmposphere, during the past century, has been linked to unprecendented global climate change. Forests and various forest management techniques have been proposed as a potential way to help sequester some ofthe atmpospheric CO2. In order to evaluate the CO2 sink potential offorests, a good understanding oftheir carbon dynamics is required over various stages oftheir development and growth.

 This dissertation reports results of a field study that focused on characterizing and quantifying CO2 emissions from various components of planted white pine (Pinus Strobus L.) forest ecosystems, growing in southern Ontario, Canada. The study site, called the Turkey Point Flux Station (TPFS), consisted offour stands, aged: 70-, 35-, 20-and 7 years-old, as of year 2009. Three major components of ecosystem respiration, Re, were studied using the chamber-method: soil respiration, Rs (both, autotrophic and heterotrophic ), foliar respiration, Rf, and live woody-tissue respiration, Rw.

 Chamber-based estimates of annual Re across the four different stands were: 1527 ± 137, 1313 ± 137, 2079 ± 293, and 769 ± 46 g C m^(-2) yr^(-1) for the 70-, 35-, 20-, and 7-year-old stands, respectively, and were generally higher compared to literature reported values. Annually Rf accounted for 48, 40, 58, and 31% of Re at the 70-, 35-, 20-, and 7-year-old stands, respectively, and dominated Re during the growing season at the three oldest stands. In contrast, Rs was the dominant Re component at the youngest stand and during the winter months at all four sites. Annually Rs accounted for 44, 40, 29, and 69 % ofRe across the respective TPFS sites. Rw was the smallest component of annual Re, accounting for only 9, 15, 13 and 0.1 % ofRe, respectively. Differences in leaf area indices among the stands were responsible for most ofthe intersite variability in Re, as well as for differences between Re values obtained in this study and those reported in the literature. Results from this study highlight the importance of considering site age and knowledge ofpast land-use history when assessing carbon budgets of afforested or planted ecosystems. They also suggest that Rf may be the more dominant and determinant component ofRe in young to mature afforested stands, which is in contrast to the widely reported Rs dominance of Re in forest ecosystems.

 Soil respiration was studied in detail across TPFS, as part ofthis dissertation, to determine the driving factors ofits temporal variability, considering seasonal, interannual (3 years ofmeasurements) and decadal (over the TPFS age-sequence) timescales. The range ofRs values across TPFS over the course of three study years was 539 ± 31 to 732 ± 31 g C m^(-2) yr^(-1). In general, annual soil emissions from the oldest stand were higher compared to those from the youngest two stands. However, emissions from the 35-year-old stand were comparable to those from the 20-and 7-year-old stands. Intersite differences in soil emissions were driven mostly by stand physiology, while interannual differences relfected interannual variability in climatic factors, as well as differences in stand physiology that modified the site's microclimates. In particular, results from this study suggest that soil moisture may have a larger
effect on the heterotrophic rather than on the rhizospheric component of soil respiration in these forest ecosystems, supporting evidence from other literaturereported studies.
Finally, the chamber-based Re values derived in this study were compared with Re values derived from congruent eddy covariance measurements at TPFS. Based on annual totals, Re calculated from chamber measurements overestimated Re calculated from eddy covariance measurements on average by: 18, 75, 24 and 39% at the 70-, 35-, 20-, and 7-year-old stands, respectively. These results highlight the continued need to resolve the discrepancy between the two methodologies used to estimate Re, before measurements from both methods can be used together to make conclusions about the composition of forest carbon budgets.

 As part of this dissertation, a statistical method of data analysis was used to implement temporal flexibility in the conventional Q10 model, widely used to simulate various Re components of forested ecosystems. The outcome of that analysis highlighted two things: a) for the case of soil respiration, the exponential relationship between Rs and Ts may be limited to the so called "ecologically optimum Ts range" for fine root growth; b) the functional form of the Q10 model is inadequate for simulating the Rs-Ts relationship across a wide range ofTs values, even after the implementation of temporal flexibility into the model, which allowed both of its model parameters to vary. The consequence of the latter result led to the development of a new empirical model -the Gamma model -for use in simulating respiration with temperature. The statistical method and the new emprical model were used to simulate CO2 emissions in this study and to identify additional environmental and physiological factors that explained some of the variability in the individual Re components across TPFS. Thus, temperature was found to be the dominant controlling factor of respiration at all four sites. However, occurrence of precipitation events, vapour pressure deficit, photosynthetically active radiation, the thickness ofthe LFH soil horizon (i.e. litter layer), and soil nutrients, were also shown to explain some ofthe variability ofthe various respiratory components.

 This dissertation fills some of the gaps in literature on studies of Re component fluxes ofplanted young to mature forests, especially of those growning in the temperate climate of eastern North America, where afforestation and plantations are most likely to occur. The study should be of interest to carbon cycle modellers, field ecologists, the eddy covariance community. It should also be of interest to those involved in forest carbon accounting, management, and policy development, by adding knowledge to our understanding of global carbon cycling and the potential for using afforested sites in global warming mitigation attempts.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Especial Skills

contributor:
Lee, Timothy D.
Kinesiology

subject: motor skills, memory, practice, performance, athlete, especial skill, practice

abstract:
 Considerable controversy exists about how motor skills come to be represented in memory as a product of practice. One line of research advocates specificity effects, whereby skills are considered highly specific to the conditions under which they are learned. An alternative view suggests that motor control is flexible and non-specific; that motor skills are represented in a more general manner, whereby the representation is an abstraction of the products ofpractice. Although experimental findings exist that support both specificity and generality of motor skills, such evidence has emerged from very different experimental conditions and paradigms, making direct comparisons difficult. An important and interesting question then is what would happen if both specificity and generality effects could be documented within a single paradigm? And what could be said about motor control theory if such effects co-exist?

 The possibility that a single memory representation may be developed for an entire class of skills (i.e., generality), but that performance of one member of that class may be distinguished from the rest (i.e., showing specificity effects) was examined. The basketball set shot (characterized by the feet remaining planted on the floor during execution) performed by highly-skilled players represents such a class of skills. Skilled performers have massive numbers of practice attempts of the set shot, however taken predominantly at 15-ft. (free-throws from the foul-line), with only minimal practice at other locations (in front of and behind the foul-line or at different angles to the basket). The six experiments presented here examined the nature of learned memory representation of the basketball set shot in highly skilled players.

 In an initial series of experiments, skilled basketball players were required to perform a series of shots from several target locations spanning 9-to 21-ft. in line with the basket, including the foul-line at 15-ft. This task was completed using two different types of basketball shots (set shots; Experiments 1and2,jump shots; Experiment 3). Results revealed that set shot performance at the 15-ft. location was significantly better than predicted by a regression equation based on the performance at the other locations in Experiment 1 and replicated in Experiment 2. However, the superior performance at the foul line was not found in novice players (Experiment 2b) or when individuals performed jump shots (in Experiment 3). Instead, performance was accurately predicted by the regression equation. We suggested that a massive amount of practice accrued over many years of basketball shooting establishes the free throw as an especial skill -one that represents a highly specific capability among the general class of set-shot skills.

 In a follow-up series of experiments, we examined potential mechanisms underlying the emergence of the especial free throw skill with an attempt to reconcile our findings with theories of motor control. In Experiments 4 and 5 two possible explanations for the specificity effect were examined: the visual-context hypothesis (unique visual context including the visual distance and visual angle to the basket) vs. the learned-parameters hypothesis (over learned specifications for the parameterizations of the set shot at 15 ft). In Experiment 4, skilled players performed set shots from the foul line (15 ft) and locations that were equidistant (15ft) but at different angles to the basket (15°, 30°, 45° to the left and right of the foul line). Performance of the set shot at the foul line was superior to the other locations, which is consistent with our previous specificity findings. In Experiment 5, players performed set shots and jump shots at the foul line and at player-chosen "favorite" locations on the court. A double dissociation was found: performance of the set shot was superior to the jump shot at the foul line but was inferior to jump shot performance at the players' favorite locations. These results are contrary to the learned-parameters hypothesis, but consistent with the visual-context hypothesis. In our last experiment, invariance in the timing structure of set shot execution of skilled players was examined to determine if the free throw was represented by the same or a distinct generalized motor program. Results revealed that the especial free throw is not represented in memory by a separate motor program compared to other set shot skills.

 Overall, these experiments provided evidence that the free-throw is an especial skill, one which, as a result of massive amounts of practice, has a special status within a generalizable class of motor skills, and which is distinguished by its enhanced performance capability relative to the other members of the same class. The co-existence of skills represented by both specificity and generality effects have theoretical and practical implications which are discussed and warrant further investigation.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Definite Forms in Valued Fields

contributor:
Haskell, Deirdre
Mathematics

subject: valued, fields, subsets, henselian

abstract:
 Let K = (K, v, ... ) be a model of a model-complete theory, T of valued fields. We
characterise, for certain definable subsets S of K^n, the collections of S-T-integral
definite and S-T-infinitesimal definite rational functions. Specifically, we consider
subsets S defined by both integrality and infinitesimality conditions for the theories of
algebraically closed valued fields, p-adically closed fields, two model-complete theories
of valued D-fields and in two model-complete theories of henselian residually valued
fields.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Gateways and Gatekeepers: Walking Through International Relations

contributor:
Stubbs, R.
Political Science

subject: gateway, initiatives, international, gatekeepers, political, economy,

abstract:
 This research project is based on the increasing importance states like Canada and Singapore give to their gateway initiatives, marketing cities like Singapore and Vancouver, as bridges between the East - mainly understood as the People's Republic of China - and the West. I am interested in the everyday life changes developing in Singapore and Vancouver as a result of these gateway initiatives in the business and education sectors, notably when it comes to catering to international students and young professionals.

 In trying to understand how gateways between East and West are experienced in everyday life, I argue that these initiatives take meaning through the everyday actions of individuals and community associations embodying these gateways. More specifically, I am interested in the actions of what I call gatekeepers: Chinese community associations well established in Singapore and Vancouver that have to adapt, influence and appropriate these gateway initiatives.

 It is my contention that both gateway projects in Singapore and Vancouver, Canada are based on neo-liberal assumptions with respect to profiting economically from a specific international context in which the economic rise of China is marketed to the West. The stories of community associations and individuals are giving to these projects specific nuances and goals that reflect both broader trends in the international political economy, such as the use of international education to migrate to Western countries, and smaller perspectives, such as transnational survival strategies of families.

 In this dissertation, I examine more thoroughly the structural limitations neo-liberal assumptions of these gateway projects create on: who is seen as a desirable migrant for/at the gateway, how community associations ought to adapt to stay relevant within these gateways and how exclusions are created along identity lines and privilege assumed within a neo-liberal framework.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: The US/UK - Iraq War, 1991-2003: How a Process Model of Violence Illuminates War

contributor:
Preston, Richard
Anthropology

subject: Iraq, 1991, 2003, Wars, US/UK, peace, sanctions, "belligerent occupation", violence

abstract: A conventional view of events in contemporary Iraq since 1990 suggests that there were two wars in 1991 and 2003 between Iraq and a US/UK led cohort of countries separated by an interval of relative peace marked by the imposition of economic sanctions on the country. This dissertation proposes an alternative view, arguing that the war with Iraq was one continuous war that began in 1991 and ended in 2003, followed by what is correctly called "belligerent occupation". A process oriented model of violence bridges two divergent literatures in the field of Anthropology-the anthropology of war and the ethnography of violence-and acts as a lens with which to see war with greater definition; and subsequently, to see that there was but one war with Iraq. The understanding ofviolence I propose illuminates the substance and process of war and is articulated through a careful analysis of three realms of violence. The Physical Realm is where harm is done to the bodies of individuals. This realm exists in the immediate context of the Network Realm, where violence is embedded in social institutions and processes. The Network Realm is in turn sustained by the Symbolic Realm, where violence is enmeshed in broader cultural symbol systems that have the power to create and sustain an ethos in which harm towards others is enabled. Each of these realms contributes to the creation and sustenance of war, yet the symbolic realm remains the primary key to enabling violence in both network and physical realms. Each realm of violence is illustrated in this dissertation by examples from the US/UK - IRAQ War, 1991-2003, drawn from my experience of living in the country and extensive historical research. The argument of this dissertation imposes a different structure on how the course of events now unfolding in the geographical region of Southwest Asia is understood. In this narrative there is a series of escalating stages. A long-standing conflict between the governments of Iraq and Kuwait was escalated when the Government of Iraq occupied the country of Kuwait in 1990. When a cohort of countries led by the US government intervened in the occupation of Kuwait, the conflict escalated into a state of war which lasted until 2003. Eventually that war was ended by yet another occupation; this time, however, it was the country of Iraq that was occupied. At the time of completing this dissertation there is a great deal of internal resistance to the occupation of the country-the contours of how it will finally unfold remain uncertain.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: "Death Becomes Them". A Funeral Home Ethnography

contributor:
Badone, Ellen E.F.
Religious Studies

subject: religion, religious, non-denominational funeral chapels, death, ritual

abstract:
 Drawing on theoretical frameworks from Religious Studies, Anthropology and Sociology, this dissertation poses the question: How is religious meaning constructed in the face of death in contemporary North America, given that commercial establishments, non-denominational funeral chapels, have become the primary context for the performance of death rituals dealing with death, the dead and the bereaved?

 The dissertation is based on an extended period of ethnographic research at the Marlatt Funeral Home in Dundas, Ontario, a corporately owned non-denominational funeral home which serves a very diverse, but predominantly urban religious population. I concentrate on the funeral professionals as well as clergy and the bereaved in their contribution to the cultural construction and social organization of death in contemporary North America.

 While there is an extensive body of social science literature on death and funerary practices in non-Western contexts, there is very little systematic academic research on death and funeral practices in contemporary North America, in particular, in Canadian settings. My dissertation furthers the discussion started in studies by Emke (2001) and Small ( 1997) which focus on funeral practices in Newfoundland as well as studies by Bradbury (1999), Davies (2002), Howarth (1996) and Walter (1990, 1994, 1996, 1998) elsewhere in the Anglophone West by focusing on funeral practises in an urban Canadian setting This dissertation demonstrates that funeral directors perform a complicated role as mediators and ritual specialists balancing multiple domains of spirituality, emotion, personal taste, institutionalized religion, ethnicity and commerce. Furthermore, I argue that funeral directors mediate between the living and the dead, between life and death, and between this world and the afterlife, as it is conceived of by their clients.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: "People's Diplomacy": The Diplomatic Front of North Vietnam During the War Against the United States, 1965-1972

contributor:
Streeter, Stephen M.
History

subject: North Vietnam, "diplomatic front", "people's diplomacy", Revolution, United States, economic

abstract: This doctoral dissertation investigates how the Democratic Republic of Vietnam (DRV, or North Vietnam), under the leadership of President Ho Chi Minh, created a "diplomatic front" to implement "people's diplomacy." The main focus is on the period from 1965-1972 when the DRV needed these strategies to win worldwide support and sympathy for the Vietnamese Revolution. The diplomatic front consisted of Vietnamese writers, cartoonists, workers, women, students, artistic performers, filmmakers, architects, medical doctors and nurses, academics, lawyers, and sportspersons. Research in Vietnamese, American, and Canadian archives reveals that the front forged important links with antiwar activists abroad, thus lending greater credibility to their efforts to portray North Vietnam in a positive light. People's diplomacy made it difficult for the United States to prolong the war because the North Vietnamese, together with the peace movment abroad, brought popular pressure on U.S. President Lyndon Johnson to end the war. People's diplomacy was much more effective than traditional DRV diplomacy in gaining the support and sympathy of Westerners who were averse to communism. People's diplomacy damaged the reputation of the United States by exposing U.S. war crimes and casting North Vietnam as a victim of American imperialism. As a result, many of America's Western allies did not send troops or provide aid to South Vietnam. People's diplomacy also helped North Vietnam gain crucial economic, military, and diplomatic support from the Soviet Union, China, Eastern Europe, Cuba and North Korea.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Reading Political Hope: Temporal And Historical Modelling In Contemporary Canadian Fiction

contributor:
Coleman, Daniel
English

subject: time, history, Allan Donaldson, Maclean, Joy Kogawa, Obasan, Margaret Laurence, The Diviners, Lee Maracle, Daughters are Forever

abstract: This dissertation examines explicit and implicit conceptualizations of time and history in four contemporary Canadian novels: Allan Donaldson's Maclean, Joy Kogawa's Obasan, Margaret Laurence's The Diviners, and Lee Maracle's Daughters are Forever. Performing close textual analysis from a posture of 'deliberate empathy,' the author identifies several key textual devices and concepts that signal the texts' alternate ideas about time and history. These include temporal simultaneity, historical multiplicity, and the presence of the past. Drawing on critical work from fields including literary theory, globalization and cultural studies, indigenous studies and anthropology, the author investigates the political significance of the texts' different historical and temporal models. She argues that the way individuals and cultures understand time and history bears significant influence on the ways in which they understand their ethical relationships with and responsibility toward the world around them. The dissertation closes with a call for further engagement with questions of temporality and for continued efforts to link pedagogical activity to struggles for human rights.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Spectroscopic & Functional Magnetic Resonance Imaging of First and Multiple Episode Depressed Patients

contributor:
Hall, Geoffrey B.C.
Medical Sciences

subject: Major Depressive Disorder (MDD), patients, cognitive, spectroscopic, magnetic, resonance, depressed

abstract:
 Major Depressive Disorder (MDD) is a common affective disorder associated with persistent states of negative mood and selective cognitive impairments. Fronto-temporal dysregulation in MDD patients is thought to contribute to the symptoms seen in these patients.

 Based on prior evidence of structural and functional alterations in the hippocampus (Hc) and prefrontal cortex (PFC) in MDD patients, we were interested in examining the changes in cerebral function that underlie the cognitive dysfunction seen in two different MDD populations. We studied psychotropically naïve depressed patients experiencing their first treated episode (FTE) of depression, MDD patients who had experienced multiple past treated episodes (MTE) of MDD and healthy controls.

 Two functional magnetic resonance imaging studies (fMRI) were conducted. The first study used an Hc dependent process dissociation task to examine Hc activation during recollection memory. The second fMRI study examined the activation in the PFC during reward and punishment conditions of a reversal-learning paradigm. Finally, we conducted magnetic resonance spectroscopy scans to measure levels of metabolites indicative of neuronal and glial cell integrity in the Hc of depressed patients and controls.

 We observed differing results across all three studies in our FTE and MTE depression groups. Our studies examining the Hc suggest that MTE patients have decreased activation in this region as well as corresponding memory errors during recollection memory. Additionally, these patients have smaller Hc volume and signs of increased neuronal membrane turnover. Conversely, our FTE patients displayed heightened Hc activation without memory deficits. Moreover, FTE patients had signs of increased glial cell density in the Hc without volumetric differences in this region. Our examination of reward processing revealed several health-to-illness gradients of activation in areas as the nucleus accumbens, anterior cingulate and ventral prefrontal cortices during the processing of rewards and punishers.

 These findings suggest that several regions in the brain may be sensitive to the impact of disease burden and repeated episodes of MDD. In the Hc, first treatment patients may engage in compensatory processes during the early stages of illness that are attenuated with repeated episodes of illness. Moreover, reward processing may be affected in the early course of the disorder, however with a protracted course of illness these regional alterations in activation become more pronounced.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Advances in Sparse Analysis with Applications to Blind Source Separation and EEG/MEG Signal Processing

contributor:
Reilly, James P.
Electrical and Computer Engineering

subject: sparsity, signal, blind source, EEG/MEG, linear

abstract:
 The focus of this thesis is on the utilization of the sparsity concept in solving some challenging problems, e.g., finding a unique solution to the under-determined linear system of equations in which the number of equations is less than the number of unknowns. This concept is extended to the problem of solving the under-determined blind source separation (BSS) problem in which the number of source signals is greater than the number of sensors and both the mixing matrix and the source signals are unknowns. In this respect we study three problems:

 1. Developing some algorithms for solving the under-determined linear system of equations for the case of a sparse solution vector. In this thesis we develop a new methodology for minimizing a class of non-convex (concave on the non-negative orthant) functions for solving the aforementioned problem. The proposed technique is based on locally replacing the original objective function by a quadratic convex function which is easily minimized. For a certain selection of the convex objective function, the existing class of algorithms called Iterative Re-weighted Least Squares (IRLS) can be derived from the proposed methodology. Thus the proposed algorithms are a generalization and unification of the previous methods. In this thesis we also propose a convex objective function that produces an algorithm that can converge to a sparse solution vector in significantly fewer iterations than the IRLS algorithms.

 2. Solving the under-determined BSS problem by developing new clustering algorithms
for estimating the mixing matrix. The under-determined BSS problem is usually solved by following a two-step approach, in which the mixing matrix is estimated in the first step, then the sources are estimated in the second step. For the case of sparse sources, the mixing matrix is usually estimated by clustering the columns of the observation matrix. In this thesis we develop three novel clustering algorithms that can efficiently estimate the mixing matrix, as well as the number of sources, which is usually unknown. Numerical simulations verify the efficiency of the proposed algorithms compared to some well known algorithms that are usually used for solving the same problem.

 3. Extraction of a desired source signal from a linear mixture of hidden sources when prior information is available about the desired source signal. There are many situations in which one is interested in extracting a specific source signal. The a priori available information about the desired source signal could be temporal, spatial, or both. In this thesis we develop new algorithms for extracting a desired sparse source signal from a linear mixture of hidden sources. The information available about the desired source signal, as well as its sparsity, are incorporated in an optimization problem for extracting this source signal. Four different algorithms have been developed for solving this problem. Numerical simulations show that the proposed algorithms can be used successfully for removing different kind of artifacts from real electroencephalographic (EEG) data and for estimating the event related potential (ERP) signal from synthesized EEG data.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: An Empirical Investigation of Economic Aspects of Physician Services Utilization

contributor:
Hurley, Jeremiah
Racine, Jeffery
DeCicca, Philip
Economics

subject: empirical, economics, physicians, health, services, income

abstract:
 This thesis is an empirical exploration into a range of issues related to the economics of the utilization of physician services. Physicians play an important role in a health care system as physicians are a patient's primary point of contact with the health care system and physicians are predominantly responsible for directing how patients use other health care resources. In particular, physicians are at the center of Canada's universal public insurance system with first dollar coverage for medically necessary physician and hospital services.

 The thesis comprises three separate essays. The first essay has a methodological focus on statistically modeling and predicting the use of general practitioners (GPs) when use is measured as the number of GP visits. The essay compared a state-of-the-art parametric latent class negative binomial model to a nonparametric kernel conditional density estimator, and evaluated how well each was able to fit the observed data and predict physician use.

 The second and third essays look at more substantive policy questions. The second essay investigates how the supply of GPs and specialists affects the mix of physician services received by individuals. A persistent concern in many health care systems is how variations in the supply of physicians will impact the use of physician services. The results suggest concerns about concerns of patient access and receipt of care in the presence of a shortage of specialists may be mitigated, all else equal, if patients are able to substitute GP services for specialist services.

 The third essay examines income-related inequity in the use of physician services by asthmatics and diabetics, relative to the general population, and the contributions of different factors to income-related inequality using the concentration index approach.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Synthesis and Functional Properties of Ni-Mn-Ga Ferromagnetic Shape Memory Thin Films

contributor:
Niewczas, Marek
Botton, Gianluigi
Materials Science and Engineering

subject: synthesis, Ni-Mn-Ga, memory, thin films, magnetic

abstract:
 The purpose of this work was to develop a growth pathway for synthesis of high-quality ferromagnetic Ni-Mn-Ga shape memory thin films and to understand their functional properties.

Two groups of Ni-Mn-Ga films were prepared using the pulsed laser deposition technique. One group was grown on (100) YSZ ((Zr,Y)O2 with ZrO2:Y2O2=92:8) and was used to study the thermal, magnetic, and magnetocaloric properties. The other group was deposited on (100) MgO. These films were fabricated into free-standing micro-bridges.

These Ni-Mn-Ga films were synthesized in a previously unexplored high temperature deposition regime. The temperatures employed encouraged the development of the desired micrometer-size highly twinned martensite grain structure while the general problem of preferential evaporation of the volatile elements at elevated temperatures was solved by using a manganese and gallium enriched target.

 The films grown on (100) YSZ exhibit a self-reversible, magnetically induced reorientation of the martensite variants (MIR), which is temperature dependent. The mechanism associated with the self-activated reversibility in the MIR effect was established through a detailed characterization of the texture, microstructure, and magnetic domain structure of the films.

 The synthesized films also show a large magnetocaloric effect (MCE), which is particularly strong at low magnetic fields. The effect is associated with an overlapped ferromagnetic and martensitic phase transition. Detailed characterization of these transitions allow for an understanding of the role each phase transition plays in determining the level of enhancement to a standard MCE governed only by the ferromagnetic phase transition.

 Ni-Mn-Ga free-standing micro-bridges were fabricated using photolithography followed by wet chemical etching. Microstructural evolution of the martensitic variants resulting from changes to the stress field in the detached areas was studied in the context of potential film applications for micro-actuators.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Study of the Dipolar Ising System LiHoxY1-xF4 Using Muon Spin Relaxation/Rotation

contributor:
Luke, Graeme M.
Physics and Astronomy

subject: LiHoxY1-xF4, magnetic, dipolar, ferromagnet, Ising, Muon, spin

abstract:
 LiHoxY1-xF4 is an insulating system where the Ho ions are magnetic. The crystal field gives an Ising character to the Ho ions, and the dominant interaction between them is through magnetic dipolar fields. For x=1, the system is a ferromagnet with a critical temperature of 1.54 K. The critical temperature decreases as x is decreased until x~0.25. At that point the long range order is destroyed, giving rise to a state with some characteristics of spin glass behavior.

 The study of this system is important because its Ising nature makes it a test ground for theoretical models. Interestingly, not only experiments and theory diverge in many points, but experimental data from different research groups are contradictory. In order to contribute to a clearer experimental picture, we performed μSR measurements in this system and we present our results in this thesis.

 In the ferromagnetic samples (x=1 and 0.45) we found that the internal field distribution at the muon site is quite broad, even in the x=1 system. Then it is possible that the magnetic field distribution at the Ho ions is broad as well. We show qualitatively how this broadening could explain a feature of the field-temperature phase diagram which is still not understood.

 For the more diluted samples (x=0.25, 0.12, 0.08, 0.045 and 0.018), we
found that they all have the same qualitative behavior as a function of temperature and magnetic field. Our analysis of the data did not show any feature of canonical spin glass behavior. Instead, an analysis using dynamical Kubo-Toyabe functions show a temperature independent fluctuation rate of the Ho moments below ~0.5 K for all these samples. This behavior is characteristic of cooperative paramagnetic systems. We also found that the low temperature fluctuation rate decreases as x is decreased.

 To analyze the data from LiHoxY1-xF4 we developed microscopic models of μSR signals. These models are presented in this thesis and they correspond to stochastic models of signals using stretched magnetic field distributions; and the modeling of signals from systems with F-μ-F bond formation where the set of bonds does not have cubic symmetry.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Joint Multitarget Tracking and Classification Using Aspect-Dependent Measurements

contributor:
Kirubarajan, T.
Electrical and Computer Engineering

subject: joint, target, tracking, classification, aspect-dependent, multitarget

abstract:
 In this thesis new joint target tracking and classification techniques for aspect-dependent measurements are developed. Joint target tracking and classification methods can result in better tracking and classification performance than those treating these as two separate problems. Significant improvement in state estimation and classification performance can be achieved by exchanging useful information between the tracker and the classifier. Target classification in many target tracking algorithms is not typically done by taking into consideration the target-to-sensor orientation. However, the feature information extracted from the signal that originated from the target is generally a strong function of the target-to-sensor orientation. Since sensor returns are sensitive to this orientation, classification from a single sensor may not give exact target classes. Better classification results can be obtained by fusing feature measurements from multiple views of a target. In multitarget scenarios, handling the classification becomes more challenging due to the identifying the feature information corresponding to a target. That is, it is difficult to identify the origin of measurements. In this case, feature measurement origin ambiguities can be eliminated by integrating the classifier into multiframe data association. This technique reduces the ambiguity in feature measurements while improving track purity.

 A closed form expression for multiaspect target classification is not feasible. Then, training based statistical modeling can be used to model the unknown feature measurements of a target. In this thesis, the Observable Operator Model (OOM), a better alternative to the Hidden Markov Model (HMM), is used to capture unknown feature distribution of each target and thus can be used as a classifier. The proposed OOM based classification technique incorporates target-to-sensor orientation with a sequence of feature information from multiple sensors. Further, the multi-aspect classifier can be modeled using the OOM to handle unknown target orientation. The target orientation estimation using OOM can also be used to find improved estimates of the states of highly maneuverable targets with noisy kinematic measurements. One limiting factor in obtaining accurate estimates of highly maneuvering target states is the high level of uncertainty in velocity and acceleration components. The target orientation information is helpful in alleviating this problem to accurately determine the velocity and acceleration components.

 Various simulation studies based on two-dimensional scenarios are presented in this thesis to demonstrate the merits of the proposed joint target tracking and classification algorithms that use aspect-dependent feature measurements.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Quantifying Chromophore Concentration in Tissue Simulating Phantoms Using an Optical Detection System Based on an Integrating Sphere

contributor:
Hayward, Joseph E.
Medical Physics

subject: integrating, sphere, system, optical, tissues, quantifying

abstract: An integrating sphere system has been developed to study the optical properties of biological tissues non-invasively, over a broad spectral range with the ultimate goal of quantifying erythema resulting from external beam radiotherapy. An empirical model was defined to calculate the absorption coefficient, μa, from the normalized integrating sphere signal, R *, and the reduced scattering coefficient, μ's As erythema is associated with an increase in the apparent concentration of oxygenated haemoglobin in the skin, the potential of the technique in quantifying erythema was assessed using measurements made in homogenous tissue simulating phantoms containing whole horse blood. After system validation in this simple model, a two-layer model was investigated. Whole blood from a horse was added to the bottom layer, while the top layer was fixed at an optical thickness simulating the epidermis. Reflectance measurements were made through the top layer while the bottom layer was deoxygenated using yeast. The retrieved concentrations of oxy- and deoxygenated haemoglobin were used to calculate the total haemoglobin concentration and the haemoglobin oxygen saturation. Errors in estimating the total haemoglobin concentration ranged from 3-12%; decreasing as a broadband absorber was added to the top layer. Preliminary in vivo measurements were also performed on areas of erythema induced by a topical anesthetic. For regions of erythema there was an increase in the apparent haemoglobin oxygenation which correlates to values of the erythema index calculated from the definition established by Dawson et al. These results demonstrate that the apparent haemoglobin oxygenation has the potential to be used as a surrogate in quantifying erythema.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Thermodynamic Study on Vapourization of Niobium Oxides From Slag Melts

contributor:
Coley, Kenneth S.
Materials Science and Engineering

subject: niobium, slag, vapourizing, oxides, thermodynamic, temperature

abstract:
 The partitioning of niobium to slag and gaseous niobium oxide vapourizing from metal/slag may cause niobium losses and erratic recovery rates in steelmaking practices. Knowledge of the volatility and activities of niobium oxides in slag melts are of great value for both theoretical evaluation and practical applications in niobium microalloyed steels. Because of the multi-valence state of niobium ions in slags, the behaviour of niobium in metallurgical slags is complicated. So far, little systematic attempts have been made and activity data of niobium oxides in slags are extremely scarce. The aim of this study is to determine precise data on the vapour pressures of niobium oxides, and consequently, to obtain information on thermodynamic quantities of niobium oxides in slag melts.

 The thermodynamic properties of niobium oxide in CaO-SiO2-NbOx and CaOSiO2-Al2O3-NbOx slag melts were determined by employing the transpiration method from 1800-1873K under a controlled atmosphere. To confirm the validity of the transpiration method for the measurement of thermodynamic properties, the binary alloy system silver-gold was chosen for a comparison with the same property which has been measured by other recognized procedures. The agreement with literature results confirmed that the measurement yields reliable results for thermodynamic activity data by the transpiration method.

 The vapourization of liquid Nb2O5 was studied as a function of partial pressure of oxygen in the system and this confirms that atmosphere control is the essential condition for the vapourization study. The gaseous niobium oxide species was verified to be NbO2; hence, Nb2O5 vapourizes by the reaction Nb2O5(1) = 2NbO2(g)+1/2O2(g). Heat of vapourization was estimated by applying the second law method and comparison with the literature showed a fairly good agreement.

 The thermodynamic properties of niobium oxide in the slag system of CaO-SiO2-NbOx and CaO-SiO2-Al2O3-NbOx were measured by varying the experimental conditions of slag basicities, slag compositions, temperature and oxygen partial pressures. From the basicity dependency of the activity coefficient for each oxide in this study, it is proposed that niobium oxide behaves as an amphoteric oxide and niobium pentoxide as an acidic oxide. On the other hand, it was observed in the redox equilibrium experiment that NbO2.5 becomes predominant as the slag basicity increases. However, insufficient interaction parameters as well as parameter conversions prevent the application of the regular solution model. The co-relationship between the ionic diameter and ionic energy was discovered and shows good agreement with calcium oxide and silicon oxide. With the interaction parameter and converting parameter attained, the regular solution model shows good agreement for the activity coefficients between measurement and calculation.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Efficient Computation of Regularities in Strings and Applications

contributor:
Smyth, William F.
Computing and Software

subject: regularities, strings, computing, algorithm, output,

abstract:
 Regularities in strings model many phenomena and thus form the subject of extensive mathematical studies. Perhaps the most conspicuous regularities in strings are those that manifest themselves in the form of repeated subpatterns, that is, repeats, multirepeats, repetitions, runs and others. Regularities in the form of repeating substrings were the basis of one of the earliest and still widely used compression algorithms and remain central in more recent approaches. Repeats and repetitions of lengthy substrings in DNA and protein sequences are important markers in biological research.

 A large proportion of the available algorithms for computing regularities in strings depends on the prior computation of a suffix tree, or, more recently, of a suffix array. The design of new algorithms for computing regularities should emphasize conceptual simplicity, as well as both time and space efficiency.

 In this thesis, we investigate mathematical and algorithmical aspects of the computation of regularities in strings.

 The first part of the thesis is the development of space and time efficient nonextendible (NE) and supernonextendible (SNE) repeats algorithms RPT, shown to be more efficient than previous methods based on tests using different real data sets. In particular, we describe four variants of a new fast algorithm RPT1 that, based on suffix array construction, computes all the complete NE repeats in a given string x whose length (period) p ≥ pmin, where pmin ≥ 1 is a user-specified minimum. RPT1 uses 5n bytes of space directly, but requires the LCP array, whose construction needs 6n bytes. The variants RPT1-3 and RPT1-4 execute in O(n) time independent of alphabet size and are faster than the two other algorithms previously proposed for this problem. To provide a basis of comparison for RPT1, we also describe a straightforward algorithm RPT2 that computes complete NE repeats without any recourse to suffix arrays and whose total space requirement is only 5n bytes; however, this algorithm is slower than RPT1. Furthermore, we describe new fast algorithms RPT3 for computing all complete SNE repeats in x. Of these, RPT3-2 executes in O(n) time independent of alphabet size, thus asymptotically faster than the methods previously proposed. We conclude with a brief discussion of applications to bioinformatics and data compression.

 The second part of the thesis deals with the issue of finding the NE multirepeats in a set of N strings of average length n under various constraints. A multirepeat is a repeat that occurs at least m times (m ≥ 2) in each of at least q ≥ 1 strings in a given set of strings. We show that RPT1 can be extended to locate the multirepeats based on the investigation of the properties of the multirepeats and various strategies. We describe algorithms to find complete NE multirepeats, first with no restriction on "gap length" (that is, the gap between occurrences of the multirepeat), then with bounded gaps. For the first problem, we propose two algorithms with worst-case time complexities O(Nn+αlog2N) and O(Nn+α) that use 9Nn and 10Nn bytes of space, respectively, where α is the alphabet size. For the second problem, we describe an algorithm with worst-case time complexity O(RNn) that requires approximately 10Nn bytes, where R is the number of multirepeats output. We remark that if we set the min and max constraints on gaps equal to zero in this algorithm, we can find all repetitions (tandem repeats) in arbitrary subsets of a given set. We demonstrate that our algorithms are faster, more flexible and much more space efficient than algorithms recently proposed for this problem.

 Finally, the third part of the thesis provides a convenient framework for comparing the LZ factorization algorithms which are used in the computation of regularities in strings rather than in the traditional application to text compression. LZ factorization is the computational bottleneck in numerous string processing algorithms, especially in regularity studies, such as computing repetitions, runs, repeats with fixed gap, branching repeats, sequence alignment, local periods, and data compression. Since 1977, when Ziv and Lempel described a kind of string factorization useful for data compression, there has been a succession of algorithms proposed for computing "LZ factorization". In particular, there have been several recent algorithms proposed that extend the usefulness of LZ factorization, especially to the computation of runs in a string x. We choose these algorithms and analyze each algorithm separately, and remark on them by comparing some of their important aspects, for example, additional space required and handling mechanism. We also address their output format differences and some special features. We then provide a complete theoretical comparison of their time and space efficiency. We conduct intensive testing on both time and space performance and analyze the results carefully to draw conclusions in which situations these algorithms perform best. We believe that our investigation and analysis will be very useful for researchers in their choice of the proper LZ factorization algorithms to deal with the problems related to computation of the regularities in strings.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Modelling Long-Term Soil Moisture Dynamics of Urban Grassland Under South-Western Ontario Soil and Meteorological Conditions

contributor:
Baetz, Brian W.
Guo, Yiping
Civil Engineering

subject: soil, moisture, grassland, meteorological, water, balance, plant,

abstract:
 Soil moisture is at the centre of the water balance and is of great concern with regards to crop growth and yield, irrigation planning, fertilization, climate change and non-point source pollution control. Information on soil moisture is not widely available, resulting in researchers relying on mathematical models to gain insight into soil moisture conditions. This thesis primarily focuses on long-term soil moisture characteristics, under given climate, soil and vegetation conditions. Long-term soil moisture characteristics are best described by statistics such as average soil moisture, and its standard deviation and frequency/probability distribution. After an extensive review of existing explicit or implicit soil moisture models, a deterministic water balance model was developed to simulate soil moisture at a point within the root-zone. The hydrological processes involved in the water balance are modelled using well-established methods. The continuous simulation model is unique from other leading deterministic models as it introduces the ecohydrological perspective by modelling actual evapotranspiration as a function of plant access to soil moisture. The validation of the model demonstrates that simplified soil moisture modelling is rational and practical.

 Soil moisture modelling is dependent on various input parameters related to the climate, soil and vegetation. Both local and global sensitivity analyses were carried out to investigate which input parameters influence the soil moisture regime the most. The analyses concluded that parameters representing soil texture are most important and thereby indicated that evapotranspiration is the most dominant process as it is significantly controlled by these parameters. Due to concerns of the impact of climate change and urban stormwater management, a better understanding of urban area soil moisture dynamics is required. The applicability of the continuous simulation model was demonstrated by investigating the influence of global warming on long-term soil moisture and evapotranspiration. Statistical analyses carried out on the post-simulated long-term soil moisture values clearly showed that even though temperatures are increasing, soil moisture and evapotranspiration have also increased because of the overall increase in precipitation. This phenomenon gives insight into the precipitation characteristics being strong enough to overpower the soil moisture loss process of evapotranspiration. As a part of the overall research, an analysis on antecedent soil moisture values for the purpose of urban stormwater management was performed. Empirical equations were derived to obtain antecedent soil moisture values from soil characteristics. Antecedent soil moisture information is essential in the application of the design storm approach while designing urban stormwater management infrastructure.

 The main purpose for the development and use of the deterministic model was to better understand the statistics and sensitivity of soil moisture and not as a predictive tool.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: State Strategy for Migration Management: Canada's Two Temporary Foreign Worker Programs, The Seasonal Agricultural Workers Program & The Live-in Caregiver Program

contributor:
Coleman, William
Political Science

subject: Canadian, government, Live-in Caregiver Program, foreign, cross-border, economic,

abstract:
 This study applies an IPE approach to examine the economic conditions, motivations and interests which have driven the Canadian government and two sending countries, Mexico and the Philippines, to accept the terms and conditions of a regulatory framework encouraging short-term labour migration between them. The features of program development which underpin the Seasonal Agricultural Workers Program (SAWP) and the Live-in Caregiver Program (LCP) have not been compared side by side. Nor have the two programs been compared for the relationship that has developed over the years between the Canadian government and the two sending governments of Mexico and the Philippines. The study's core research question asks how the process of regulating cross-border labour migration works and how it is coordinated between two or more governments that form part of a migration system.

 An important research finding that emerges from the comparison is the categorization of different types of migration systems. I argue that the SAWP and LCP differ in how they are administered because relations between the various actors differ. Furthermore, what defines these relationships is the set of geopolitical and economic interests that each government carries when it negotiates the regulation of cross-border labour migration. Findings suggest that the geopolitical and economic imperative which has driven the SAWP's development is not the same for the LCP.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Terahertz Spectroscopy of Dynamic YBa2Cu3O7-δ Thin Films

contributor:
Preston, J.S.
Physics and Astronomy

subject: optical, superconductors, steady-state, spectroscopy, THz,

abstract:
 The optical properties of high temperature superconductors have long been of interest to condensed matter physicists. The majority of the research has concentrated on the steady-state properties of cuprates. Optical excitation of cuprate superconductors provides the valuable opportunity to study the dynamics of the superconducting state via the evolution of the superconducting condensate and excited quasiparticles. Terahertz (THz) spectroscopy is particularly attractive for the study of thin film cuprates, as the energies available in broad spectrum THz pulses lie below the maximum superconducting gap values. Optical pump THz probe spectroscopy utilizes a high energy infrared pulse to destroy the condensate and excite quasiparticles states out of equilibrium. The THz probe is capable of spectrally resolving the sample's temporal response to the optical perturbation. The direct measurement of both the amplitude and phase of the electric fields associated with the transmitted THz radiation allow for the calculation of both the real and imaginary parts of the conductivity. This offers the tantalizing potential of untangling the condensate's recovery from quasi-particle dynamics.

 The focus of this thesis will be upon the long timescale dynamics of YBa2Cu3O7-δ (YBCO) thin films. It has generally been believed that the condensate is fully recovered after a few picoseconds, and that the recovery of these films at longer timescales is essentially a thermal process although perhaps slowed by a phonon bottleneck. However, we will show spectral evidence that this picture cannot fully explain long lived dynamics in YBCO thin films. Specifically we see a suppression of the low frequency components of the optical conductivity. This anomaly is consistent with the formation of spatial inhomogeneity in the superconducting fraction, which likely arises from a non-uniform formation of the condensate across the film. The role of local inhomogeneity in the condensate and its effect on the conductivity of the thin film will be discussed. Evidence of intrinsic inhomogeneities in YBCO films may prove useful to the theoretical understanding of condensate dynamics in the cuprates. The spectral response of three doping levels, from optimally doped to underdoped YBCO, will also be shown, with a brief discussion of the normal state dynamics in underdoped films and the possible sensitivity of THz radiation to pseudogap dynamics.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: ON THE STABILIZATION OF NONLINEAR CONTROL SYSTEMS SUBJECT TO STOCHASTIC DISTURBANCES AND INPUT CONSTRAINTS

contributor:
Mhaskar, Prashant
Chemical Engineering

subject: Control Systems, Control Theory

abstract: This thesis investigates the broad theme of guaranteeing the stability of nonlinear control systems. In the first section, we describe the application of discrete controller for the stabilization of certain nonlinear stochastic control systems subject to unavailability of state measurements. In the second section, we consider input constrained nonlinear systems and characterize the region from which stabilization to the origin is possible. We then use this information to design a controller which stabilizes everywhere in this set.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Work Hardening and Latent Hardening of Mg Single Crystals under Uniaxial Deformation at 298K

contributor:
Niewczas, Marek
Materials Science and Engineering

subject:
Work hardening
Latent hardening
Mg single crystals

abstract:
In this thesis, work hardening and latent hardening behaviours of pure Mg single crystals were mainly studied under uniaxial deformation tests at room temperature, 298K. By uniaxial tensile/compression tests, work hardening behaviours of Mg single crystals with different orientations favoured for single and double basal <a> slip, {10-12}<10-11> twin, 2nd order pyramidal <c+a> slip and basal <a> slip + {10-12}<10-11> twin were studied. In order to investigate latent hardening behaviours among slip and twin systems, the Jackson-Basinski type latent hardening experiments in Mg single crystals at room temperature have been carried out under different types of dislocation interactions, which included: (i) the self-interactions, (ii) the co-planar interactions on the basal plane, (iii) basal <a> slip / {10-12}<10-11> twin dislocation interactions, (iv) {10-12}<10-11> twin / basal <a> slip dislocation interactions and (v) basal <a> slip / 2nd order pyramidal <c+a> slip dislocation interactions. The microstructure and micro-texture of the deformed single crystals was observed by optical microscopy (OM), scanning electron microscopy (SEM), and SEM/EBSD methods. In addition, micro- and nano-indentation measurements were performed on adjacent matrix and {10-12}<10-11> twin regions of deformed Mg single crystals and the hardness values were analyzed by the Oliver-Pharr method.

The results from the Ph.D. work provided framework for the discussion of the plastic flow in Mg single crystals and quantitative values for hardening parameters used in the crystal plasticity modelling.

abstract: Thesis

abstract: Doctor of Science  (PhD)


title: A Novel Method to Improve Quantitative Susceptibility Mapping with an Application for Measuring Changes in Brain Oxygen Saturation in the Presence of Caffeine and Diamox

contributor:
Haacke, E. Mark
Biomedical Engineering

subject:
Quantitative Susceptibility mapping
sinus mapping
magnetic resonance imaging
oxygen extraction fraction
venous oxygen saturation

abstract:
Magnetic Resonance Imaging (MRI) is a widely used, non-invasive imaging technique that provides a means to reveal structural and functional information of different body tissues in detail. Susceptibility Weighted Imaging (SWI) is a field in MRI that utilizes the information from the magnetic susceptibility property of different tissues using the gradient echo phase information. Although longer echo times (TEs) have been widely used in applications involving SWI, there are a few problems related with the long TE data, such as the strong blooming effect and phase aliasing even at macroscopic levels. In this thesis, the use of very short TEs is proposed to study susceptibility mapping. The short TEs can be used to study structures with susceptibilities an order of magnitude larger (such as air and bones in and around the brain sinuses, skull and teeth) than those within soft tissue. Using a new iterative susceptibility mapping technique that we recently developed, it becomes possible to map the geometry of such structures, which to date has proven difficult due to the lack of water content (for sinuses) or due to very short T2* (for bones).

The method of phase replacement inside the sinuses proposed in this thesis provides more accurate phase information for the inversion than assuming zero or some arbitrary constant inside these structures. The first and second iterations were responsible for most of the changes in mapping out the susceptibility values. The mean susceptibility value in the sphenoid sinus is calculated as +9.3 ± 1.1ppm, close to the expected value of +9.4ppm for air. The reconstruction of the teeth in the in-vivo data provides a mean Δχ(teeth-tissue)=–3.3ppm, thanks to the preserved phase inside the jaw. The mean susceptibility inside a relatively homogeneous region of the skull bone was measured to be Δχ(bone-tissue)=–2.1ppm. Finally, these susceptibilities can be used to help remove the unwanted background fields prior to applying either SHARP or HPF.

In addition, the effects of the background field gradient on flow compensation are studied. Due to the presence of these background gradients, an unwanted phase term is induced by the blood flow inside the vessels. Using a 3D numerical model and in vivo data, the background gradients were estimated to be as large as 1.5mT/m close to the air-tissue interfaces and 0.7mT/m inside the brain (leading to a potential signal loss of up to 15%). The quantitative susceptibility mapping (QSM) results were improved in the entire image after removing the confounding arterial phase thanks to the reduced ringing artifacts.

Lastly, a novel approach to improve the susceptibility mapping results was introduced and utilized to monitor the changes in venous oxygen saturation levels as well as the changes in oxygen extraction fraction instigated by the vasodynamic agents, caffeine and acetazolamide. The internal streaking artifacts in the susceptibility maps were reduced by giving an initial susceptibility value uniformly to the structure-of-interest, based on the a priori information. For veins, the iterative results, when the initial value of 0.45 ppm was used, were the best in terms of the highest accuracy in the mean susceptibility value (0.453 ppm) and the lowest standard deviation (0.013 ppm). Using this technique, the venous oxygen saturation levels (inside the internal cerebral veins (ICVs)) for normal physiological conditions, post-caffeine and post-Diamox for the first volunteer were calculated as (mean ± standard deviation): Y_Normal = 69.1 ± 3.3 %, Y_Caffeine = 60.5 ± 2.8 % and Y_Diamox = 79.1 ± 4.0%.

For the caffeine challenge, the percentage change in oxygen extraction fraction (OEF) for pre and post caffeine results was calculated as +27.0 ± 3.8%; and for the Diamox challenge, the percentage change in OEF was calculated as −32.6 ± 2.1 % for the ICVs. These vascular effects of Diamox and caffeine were large enough to be easily measured with susceptibility mapping and can serve as a sensitive biomarker for measuring reductions in cerebro-vascular reserve through abnormal vascular response, an increase in oxygen consumption during reperfusion hyperoxia or locally varying oxygen saturation levels in regions surrounding damaged tissue.

In conclusion, our new approach to QSM offers a means to monitor venous oxygen saturation reasonably accurately and may provide a new means to study neurovascular diseases where there are changes in perfusion that affect the oxygen extraction fraction.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: Magnetic Resonance Imaging (MRI) is a widely used, non-invasive imaging technique that provides a means to reveal structural and functional information of different body tissues in detail. Susceptibility Weighted Imaging (SWI) is a field in MRI that utilizes the information from the magnetic susceptibility property of different tissues using the gradient echo phase information. Firstly, we demonstrate that using our phase replacement technique, it becomes possible to map the geometry of structures with almost no MR signal, which to date has proven difficult due to the lack of water content (for sinuses) or due to very short T2* (for bones). Secondly, the effects of the background field gradient on flow compensation were studied. Due to the presence of these background gradients, an unwanted phase term is induced by the blood flow inside the vessels. And, lastly, we present our new approach utilizing SWI data, offering a means to monitor venous oxygen saturation reasonably accurately and, potentially, a new means to study neurovascular diseases where there are changes in perfusion that affect the oxygen extraction fraction.


title: Polyelectrolytes for Therapeutic Cell Encapsulation

contributor:
Stover, Harald D. H.
Chemistry

subject: Cell, Cell encapsulation, therapeutic, protein, trannsplant, immune-isolating, gentic, microcapsules, alginate, APA, alginate-poly-L-lysine-alginate, ions, biocompatibility

abstract:
 Cell encapsulation aims at the delivery of a therapeutic protein to a patient from transplanted cells. Conventional approaches involve immune-isolating cell lines that have been genetically modified to express a therapeutic protein, in alginate-based microcapsules. The long-term success of this approach hinges on the structural stability of the microcapsules, as well as their ability to maintain an environment suitable for the long-term survival of encapsulated cells. The most commonly studied type of microcapsule is the alginate-poly-Llysine-alginate (APA) microcapsule. However, the main concern with AP A microcapsules is the Joss of structural integrity during long-term implantation due to the exchange of calcium ions with other physiological ions, as well as the loss of the polyelectrolyte overcoats.

 In order to increase the structural stability of the microcapsules, we developed and characterized a number of synthetic polyelectrolytes that undergo phase separation upon complexation, and which are capable of forming covalent cross-links. These reactive polyelectrolytes are designed to take the place of poly-L-lysine and the outer alginate layer. We also explored combining cross-linkable synthetic polyanions with sodium alginate to strengthen the Ca Alginate core, by forming a core cross-linked network extending throughout the microcapsules. The polyelectrolyte complexes, encapsulation processes and microcapsule properties were studied in detail using extensive characterization techniques, including collaborative work on cell viability and host-immune response.

 Overall, this thesis describes a novel approach and prom1smg materials for cell encapsulations that offer enhanced microcapsule resistance to chemical and mechanical stresses, while preserving the desired biocompatibility. These materials may ultimately be useful for clinical immunosuppressive therapies.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Corona Virus 229E, NL63 And OC43 Infection Of Human Monocyte-Derived Dendritic Cells: Modulation of Immune Effector Function

contributor:
Mahony, James B.
Medical Sciences

subject: virus-induced modulation, dendritic cell function, viral-immune evasion, Severe-acute respiratory syndrome, coronavirus, SARS-CoV, MDCs, myeloid dendritic cells, cellcular, cytokine production, 229E, IL-12, TNF, IP-10, CD4+, CD86

abstract:
<p> Virus-induced modulation of dendritic cell function is thought to be an effective mechanism for viral-immune evasion. The severe-acute respiratory syndrome coronavirus (SARS-CoV) has been shown to infected human myeloid dendritic cells (MDCs) and directly modulate the cellular cytokine production. The ability of other human coronaviruses to infect MDCs and impair cell immune function has not been assessed. </p>
<p> This thesis describes the infection of human MDCs with coronavirus 229E, NL63, and OC43. 229E showed productive, but limited genomic replication, nucleocapsid protein synthesis and infectious progeny release in MDCs. 229E infection stimulated IFN-α, IL-6 and MCP-1 production in MDCs, but little to no IL-12, TNF-α, IL-8, IP-10, or RANTES . 229E-infected MDCs showed poor CD80 expression, down-regulated CD86 and HLA-DR expression and were poor stimulators of CD4+ T cell proliferation. In contrast to 229E, OC43 showed persistent and productive genomic replication, nucleocapsid protein synthesis and infectious progeny release in MDCs. OC43 infection stimulated IFN-α, IL-12, IP-10 and MCP-1 production in MDCs, but little to no TNF-α, IL-6, IL-8 or RANTES . The up-regulation of maturation molecules and CD4+ T cell stimulatory capacity in OC43-infected MDCs was donor cell-dependent. In contrast to 229E and OC43, NL63 infection of MDCs was non-productive, showing no viral genomic replication, protein production or infectious progeny release. NL63 infection stimulated strong cytokine (IFN-α, IL-12, TNF-β and IL-6) and chemokine (IL-8, IP-10, RANTES and MCP-1) responses in MDCs. NL63-infected MDCs showed up-regulated CD80, CD83, CD86 and HLA-DR expression and were efficient stimulators of CD4+ T cell proliferation. </p>
<p> This study provides the first evidence that human coronaviruses other than SARSCo V can abrogate MDC immune effector function. It also provides the first side-by-side comparison of 229E, NL63 and OC43 and identifies the potential of 229E and OC43 to impair MDC cytokine production and T cell stimulation as a mechanism of immune response evasion. <p>

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Recombinant Adenovirus Vaccines, A Comprehensive Investigation of T Cell Immunity

title: T Cell Biology of Recombinant Adenovirus Vaccines

contributor:
Bramson, Jonathan
Medical Sciences

subject: disease, infectious, Vaccination, diseases, T cell immunity, Recombinant adenovirus, rAd, robust, rHuAd5, CD8+, CD4+

abstract: Vaccination is arguably the most effective tool at our disposal to prevent the morbidity and mortality associated with infectious disease. However, there are currently several infectious diseases, notably HIV, malaria and tuberculosis, for which we do not posses effective vaccines. Further complicating matters, traditional methods to construct vaccines for these diseases have been unsuccessful. Advances in our understanding of adaptive immunity have demonstrated that vaccines for these diseases likely rely upon potent T cell immunity to be effective. Recombinant adenovirus (rAd) vectors have shown great promise as vaccination platforms since they are easily constructed, stable, well-tolerated and elicit robust T cell responses. The robust activity of rAd vectors based on the human serotype 5 virus (rHuAd5) in murine and simian models merits futher investigation as a prototypic T cell vaccine. To this end, we have undertaken a comprehensive evaluation of T cell immunity following rAd vaccination. Our previous observations determined that the CD8+ T cell response produced by rHuAd5 vaccines displayed a prolonged effector phase that was associated with long-lived antigen presentation. We have further investigated the mechanisms underlying the maintenance of this memory population. Our results have revealed that the memory phenotype is not due to continual recruitment of naive CD8+ T cells. Rather, the sustained effector phenotype appears to depend upon prolonged expression of the antigen-encoding transgene from the rHuAd5 vector. Interestingly, transgene expression was only required for 60 days after which point the memory population stabilized. Further investigation of the relationship between antigen structure and the CD8+ T cell response revealed that antigens which traffic through the ER produce a CD8+ T cell response that expands more rapidly and displays a more pronounced contraction phase than antigens which are produced within the cytosol. While the exact mechanism underlying this phenomenon is not known, we suspect that pathways related to ER stress may be involved. Despite the more dramatic contraction phase associated with antigens that traffic through the ER, the memory phenotype was unchanged. Interestingly, the CD4+ T cell response was not influenced by antigen structure and displays a sharp contraction phase regardless of whether the antigen traffics through the ER or is produced in the cytosol. We further investigated the relationship between CD4+ T cell help and CD8+ T cell immunity produced by rHuAd5. Based on the partially-exhausted phenotype of the CD8+ T cells produced by rHuAd5 (diminished TNF-a production and little IL-2 production), we suspected that inadequate CD4+ T cell help may have been responsible. However, removal of CD4+ T cells did not further impair the CD8+ T cell response produced by rHuAd5. Rather, a lack of CD4+ T cell help only impacted the magnitude of the primary CD8+ T cell response generated by rHuAd5; the functionality of the CD8+ T cell population, including the ability to proliferate following secondary stimulation, were not affected by the absence of CD4+ T cells. Thus, although CD8+ T cell expansion following immunization with rHuAd5 is dependent upon the availability of CD4+ T cell help, the memory functions of the CD8+ T cell population appears to be independent of CD4+ T cell help. Finally, we compared the magnitude of the CD8+ T cell response produced by rHuAd5 and recombinant vaccinia virus. Our results demonstrated that the functionality of the early T cell response produced by both vectors were identical. However, the primary transgene-specific CD8+ T cell responses produced by rHuAd5 were significantly larger than rVV because the vector specific responses were negligible in the case of rAd but very strong following rVV inoculation. This research has contributed to our understanding of T cell immunity following rAd immunization and will assist in the construction and implementation of future vaccines.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Behavioural and Molecular Outcomes of Early Life Immune Challenge in Mice

title: Early Life Immune Challenge In Mice

contributor:
Foster, Jane A.
Medical Sciences

subject: immune system, brain, health, disease, immunogenic challenge, anxiety, depression, neurodevelopment, perturbation, neonatal, psychopathology, LPS, lipopolysaccharide, FST, BrdU, bromodeoxyuridine, doublecortin, DCX, neurocircuitry, serotonergic

abstract: Although historically treated as separate systems, there is considerable interaction between the immune system and brain. It has become increasingly clear that immunebrain communication is important to both health and disease. An immunogenic challenge given during the first postnatal week in rodents impacts the developing central nervous system (CNS) leading to long-term behavioural and molecular alterations reflective of enhanced stress-reactivity. Anxiety and depression are stress-related pathologies with a proposed neurodevelopmental origin suggesting that perturbation to neonatal immunebrain signalling may contribute to psychopathology. The current body of work examined the long-term impact of an early immune challenge on behavioural and molecular phenotypes associated with anxiety and depression. Mice were administered lipopolysaccharide (LPS) on postnatal days three and five. The emergence of anxietyrelated behaviour was characterized along the developmental trajectory of LPS-mice concurrent with changes to serotonergic neurocircuitry. Adult depressive-related behaviour was assessed in the forced swim test (FST) along with hippocampal neurogenesis as revealed by immunoreactivity for bromodeoxyuridine (BrdU) and doublecortin (DCX). The results demonstrated a sex-specific alteration in both the temporal emergence and phenotypic variant of anxiety-related behaviours displayed by LPS-mice. This was accompanied by changes to CNS serotonergic-related gene expression that coincided with a critical developmental time window essential to the establishment of emotionality. Adult LPS-mice exhibited hyperactivity during the FST that was accompanied by increased doublecortin immunoreactivity in the dorsal and ventral hippocampus, reflecting enhanced immature neuronal differentiation. The current results demonstrate that an early immune challenge impacts the developing CNS leading to enhanced emotional-reactivity. Altered serotonergic neurocircuitry and adult hippocampal neurogenesis may underlie behavioural abnormalities. The current body of work demonstrates a preeminent role for early-life immune disturbance in psychopathology and advances understanding of how immune-brain signalling impacts the developing CNS and confers risk for later disease.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Theoretical Modeling of Quantum Dot Infrared Photodetectors

contributor:
Deen, Jamal M.
Thompson, David A.
Engineering Physics

subject:
quantum dot infrared photodetectors
physical performance
theoretical model
non-equillibrium Green's functions
nano-devices
responsivity
detectivity

abstract:
Quantum dot infrared photodetectors (QDIPs) have emerged as a promising technology in the mid- and far-infrared (3-25 μm) for medical and environmental sensing that have a lot of advantages over current technologies based on Mercury Cadmium Telluride (MCT) and quantum well (QW) infrared photodetectors (QWIPs). In addition to the uniform and stable surface growth of III/V semiconductors suitable for large area focal plane applications and thermal imaging, the three dimension confinement in QDs allow sensitivity to normal
incidence, high responsivity, low darkcurrent and high operating temperature. The growth, processing and characterizations of these detectors are costly and take a lot of time. So, developing theoretical models based on the physical operating principals will be so useful in characterizing and optimizing the device performance. Theoretical models based on non-equilibrium Green's functions have been developed to electrically and optically characterize different structures of QDIPs. The advantage of the model over the previous developed classical and semiclassical models is that it fairly describes quantum transport phenomenon playing a significant role in the performance of such nano-devices and considers the microscopic device structure including the shape and size of QDs, heterostructure
device structure and doping density. The model calculates the density of states from which all possible energy transitions can be obtained and hence obtains the operating wavelengths for intersubband transitions. The responsivity due to intersubband transitions is calculated and the effect of having different sizes and different height-to-diameter ratio QDs can be obtained for optimization. The dark and photocurrent are calculated from the quantum transport equation provided by the model and their characteristics at different design parameter are studied. All the model results show good agreement with the available experimental results. The detectivity has been calculated from the dark and photocurrent characteristics at different design parameters. The results shows a trade off between the responsivity and detectivity and what determines the best performance is how much the rate of increase of the photocurrent and dark current is affected by changing the design parameters. Theoretical modeling developed in the thesis give good description to the QDIP different characteristics that will help in getting good estimation to their physical performance and hence allow for successful device design with optimized performance and creating new devices, thus saving both time and money.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Molecular Physiological Characterization of Ammonia Transport in Freshwater Rainbow Trout

contributor:
Wood, C. M.
Biology

subject:
ammonia excretion
freshwater fish gill
trout gill pavement cell
Rhesus proteins
methylamine transport
ammonia transport mechanism

abstract:
Ammonia excretion from the freshwater fish gill is thought to occur mainly via passive diffusion of NH3 aided by a favourable plasma-to-water ammonia gradient sustained by a pH gradient formed by an acidified gill boundary layer. Rhesus (Rh) proteins are the newest members of the ammonia transporter superfamily. In this thesis research, ten rainbow trout Rh cDNA sequences were cloned and characterized. Rhcg2 mRNA and H+-ATPase mRNA and activity levels were upregulated in the trout gill pavement cells in response to experimentally elevated plasma ammonia, concurrent with enhanced ammonia excretion. Controversially, Rh proteins are thought to transport C02. However, Rh mRNA levels in most tissues of hypercapnia-exposed trout remained stable suggesting that trout Rh proteins likely do not conduct C02. Xenopus oocytes expressing trout Rh proteins facilitated the bi-directional transport of methylamine, an ammonia analogue. Methylamine transport was inhibited by ammonia and sensitive to a pH gradient and the concentration of the protonated species. Use of the scanning ion electrode technique (SIET) indicated that trout Rh proteins have an ammonia affinity within the physiological range, which is greater than that for methylamine, and they transport ammonia more rapidly than methylamine. A model of ammonia excretion in
the trout gill pavement cell is proposed wherein ammonia enters via basolateral Rhbg and
exits via apical Rhcg2, binding to these channels as NH4+ but transiting as NH3. In the
gill boundary layer, NH3 combines with an H+ ion released from H+-ATPase and/or Na+/H+ exchange, forming NH4+. As low-affinity, high-capacity ammonia transporters, Rh proteins in the trout gill would exploit the favourable pH gradient formed by the acidic boundary layer to facilitate rapid ammonia efflux when plasma ammonia levels are elevated. Basal plasma ammonia levels are likely maintained by simple passive NH3 diffusion with a smaller role for Rh proteins under these conditions.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: An experimental study of driver fatigue: subjective driver fatigue score, driving performance, and driver fatigue countermeasures

contributor:
Yao, Shengji
Spence, Allan
Mechanical Engineering

subject:
Driver Fatigue
Subjective Driver Fatigue Score
Road Safety
Driving Performance
Driver Fatigue Countermeasure
Driver Fatigue Indicator
Caffeine
Music

abstract: Two experiments were conducted to study driver fatigue. The first investigated driver fatigue and driving performance. Thirty one Participants completed a questionnaire to obtain their Subjective Driver Fatigue Score (SDFS) quantifying fatigue levels. Driving performance was evaluated by measuring steering wheel, lateral position, etc. The results showed significant increases in the SDFS and driving performance impairment following simulated driving sessions. Further analysis suggested a linear relationship between the SDFS and the standard deviation of lateral acceleration.  Subjective fatigue assessment and driving performance were plotted as radar diagrams to show the multidimensional characteristics. The second experiment examined effects of caffeine and music on the SDFS, driving performance, and 8 EEG signal parameters. Initially, there was no significant inter-sessional variation in the dependent variables, suggesting all sessions were started at similar states. The final SDFS for caffeine and music sessions were significantly lower than control sessions, suggesting both inhibited subjective fatigue increase. Driving performance deteriorated less significantly in caffeine sessions than in control and music sessions. The results suggested that caffeine was more effective than music.  EEG was not changed significantly. However, the amplitude of α wave increased significantly for an extremely fatigued individual, along with vehicle drifting and micro-sleep. In conclusion, the SDFS developed in this study successfully estimated subjective driver fatigue levels and showed a linear relationship with driving performance during driving tasks. Caffeine and music reduced driver fatigue subjectively similarly, but caffeine also helped subjects maintain driving performance.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: In this project, two experiments were conducted to study driver fatigue. A subjective driver fatigue score was specially developed and used as a driver fatigue indicator. This score was sensitive to driver fatigue changes, and showed a linear relationship with the standard deviation of lateral acceleration. Two popular driver fatigue countermeasures, caffeine and music, were examined to investigate the effects on subjective driver fatigue and driving performance.  The results showed that caffeine reduced subjective driver fatigue and helped driver maintain good driving performance; however, music only helped drivers reduce subjective driver fatigue.


title: The Direct Detection and Kinetic Studies of Dimethylgermylene and Tetramethyldigermene In Solution By Nanosecond Laser Flash Photolysis

contributor:
Vargas-Baca
Capretta, Alfredo
Emslie, David J. H.
Chemistry

subject: Dimethylgermylene, GeMe2, photolysis, 1, 1-dimethyl-3-phenylgermacyclopent-3-ene, 1,1,3-trimenthyl-4-phenylgermacyclopent-3-ene, MeOH, t-BuOH, THF, lewis acid-base complexes, Bronsted acid, acetic acid, methanesulfonic acid,

abstract:
 Dimethylgermylene (GeMe2) has been generated by laser flash photolysis of 1,1dimethyl-3-phenylgermacyclopent-3-ene (23) and 1,1,3-trimethyl-4phenylgermacyclopent-3-ene (24) in hexanes at 25°C and its absorption maximum (λmax) has been unambiguously established to be 470 nm. GeMe2 decays with second-order  kinetics under these conditions (2k/ε. = (10 ± 2) x 10^7 cm s^(-1)) to give Ge2Me4 (λmax = 370 nm). Kinetic studies of the reactions of GeMe2 and Ge2Me4 with typical germylene/digermene scavengers such as 1,3-dienes, olefins, alkynes, alkyl halides, group 14 metal hydrides, carboxylic acids, and amines have been carried out.

 GeMe2 reacts reversibly with MeOH, t-BuOH and THF to form Lewis acid-base complexes which exhibit relatively strong absorption bands that are blue-shifted with respect to GeMe2 (λmax ~ 295-310 nm). The decay of the Me2Ge-MeOH complex is accelerated in the presence of a Brnnsted acid (acetic acid or methanesulfonic acid) or base (MeONa). The reactions of the Me2Ge-THF complex with sodium methoxide, methanesulfonic acid, 4,4-dimethyl-1-pentene, 2,3-dimethyl-1-butadiene, acetic acid and CC4 have also been studied in THF.

 The photochemistry of two well-known precursors to GeMe2, namely dodecamethylcyclohexagermane (14) and dimethylphenyl(trimethylsilyl)germane (18) was reinvestigated. Laser flash photolysis of 14 in hexanes led to the formation of two transients, one with λmax= 490 nm (τ < & = 10 ns) and the second with λmax= 470 nm. The latter decays with second-order kinetics with concomitant formation of a new transient with λmax= 370 nm. The transient at 470 nm is assigned to GeMe2 and that at 370 nm to Ge2Me4, based on comparisons to the results obtained from laser flash photolysis of 23 and 24. Laser flash photolysis of 18-in hexane gives rise to two absorption bands centered at λmax = 300 nm and λmax = 430 nm, which are assigned to the dimethylphenylgerrnyl radical and the conjugated gerrnene derivative 38, respectively. GeMe2 cannot be detected in laser flash photolysis experiments with this compound.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: 75As and 59Co NMR Study of the Electron Doped Ba(Fe(1-x)Co(x))(2)As(2)

contributor:
Imai, Takashi
Physics and Astronomy

subject: iron-based high temperature superconductor Ba(Fe(1-x)Co(x))2As(2)

subject: Nuclear magnetic resonance

subject: Co dopants

subject: doped superconductor

subject: cuprates

subject: antiferromagnetic spin fluctuations

subject: spin susceptibility

subject: in-plane resistivity

abstract:
We report a systematic investigation of the local electronic, magnetic, and superconducting properties of the new iron-based high temperature superconductor Ba(Fe(1-x)Co(x)As(2) (x = 0, 0.02 , 0.04, 0.082) through the measurement of 75As and 59Co NMR (Nuclear Magnetic Resonance) lineshapes, Knight shift (K), and spinlattice relaxation rate ( 1/ T1) . The 75As NMR lineshape of the undoped parent compound splits into two sets due to discrete values of hyperfine magnetic field B(c)(hf)= ±1.32 Tesla below the magnetic ordering temperature to the SDW (Spin Density Wave) state, TSDW. In contrast, for lightly Co doped samples with x=0.02 and 0.04, the 75As and 59Co lineshapes become broad and featureless below Tsnw , indicating that the ground state is no longer the commensurate SDW ordered state. The
observed lineshape is consistent with an incommensurate SDW ordered state, or a commensurate state with large distribution of hyperfine field Bhf. In the optimally doped superconductor with x = 0.082 (Tc = 22 K) , we observe two types of As sites and three types of Co sites, respectively, as expected from a binomial distribution of Co dopants. We found no evidence for induced localized moments in the vicinity of Co dopants. This finding is in remarkable contrast with the case of Zn or Ni doped high Tc cuprates, and suggests that the fundamental physics of iron-based superconductors is different from that of cu prates. The temperature dependences of 75,59K and 75,59 (1/T1T) at both 75As and 59Co sites show that Ba(Fe(1-x)Co(x))(2)As(2) exhibits spin pseudo-gap like behavior down to ~100 K for a broad Co concentration range. Below ~100 K , we observe the enhancement of residual antiferromagnetic spin fluctuations associated with inter-band spin excitations between the hole and electron Fermi surfaces even for x= 0.082. This effect is suppressed in the overdoped sample with x= 0.099, and Tc decreases. Therefore, we suggest that antiferromagnetic spin fluctuations play a crucial role in the superconducting mechanism of Ba(Fe(1-x)Co(x))(2)As(2) . We also demonstrate that the superconductivity arises from a novel electronic state with spin susceptibility Xs ~ constant and in-plane resistivity P(ab)~T, which is not consistent with canonical Fermi-liquid behavior.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Accelerated Monte Carlo based Quantitative SPECT Reconstruction

contributor:
Farncombe, Troy H.
Electrical and Computer Engineering

subject: Nuclear Imaging, Radionuclides, Clinical Application of Nuclear Imaging, Gamma, Photon, Monte Carlo, Random Number Generation, Photon Path

abstract:
Thesis
Doctor of Philosophy (PhD)


title: The Structural Politics of Totem and Taboo

subject: religious theory, ontogenetic, phylogenetic evolution, primal horde parricide,

abstract:
 Freud's Totem and Taboo was one of the more controversial additions to the literature of religious theory. The two major hypotheses of the work are the parallel between ontogenetic and phylogenetic evolution, and the primal horde parricide. The first hypothesis has rarely been taken seriously. The second, although never verified with anthropological evidence, has generated further hypotheses based upon its value as a symbolic representation rather than an actual occurrence. Paul Roazen has suggested that the primal horde parricide hypothesis possesses characteristics similar to those of most social contract theories. He posited, in light of this, that Totem and Taboo ought to be considered a kind of social contract, although it has never been thought of this way.

 The major school of philosophical thought which has continued to maintain interest in Totem and Taboo, long after the main anthropological assertions have been dispelled, is the French structuralist movement and its successors. Through the work of Levi-Strauss, carried on with theorists such as Lacan, Bataille, and Derrida, Totem and Taboo has maintained value as important work. The French structuralists have sustained a tradition that began with Rousseau of combining mathematical reasoning and linguistic theory together with anthropological speculation raised in Totem and Taboo. Thus in light of Roazen's hypothesis and the structuralist treatment of Totem and Taboo, together with Bryan Skyrms' s recent work on Rousseau and the mathematics of social contract theory, I posit that Totem and Taboo is comparable to Rousseau's Social Contract, in which human nature, politics, myth and mathematics merge. Implicitly Totem and Taboo contains a novel theory of the political development of society.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)