VictorJuiz/thesis huggingface dataset:
Nanoscale Interfaces in Colloidal Quantum Dot Solar Cells: Physical Insights and Materials Engineering Strategies
Keywords: Quantum Dots
Photovoltaics
Nanotechnology

With growing global energy demand there will be an increased need for sources of renewable energy such as solar cells. To make these photovoltaic technologies more competitive with conventional energy sources such as coal and natural gas requires further reduction in manufacturing costs that can be realized by solution processing and roll-to-roll printing. Colloidal quantum dots are a bandgap tunable, solution processible, semiconductor material which may offer a path forward to efficient, inexpensive photovoltaics. Despite impressive progress in performance with these materials, there remain limitations in photocarrier collection that must be overcome. This dissertation focuses on the characterization of charge recombination and transport in colloidal quantum dot photovoltaics, and the application of this knowledge to the development of new and better materials. Core-shell, PbS-CdS, quantum dots were investigated in an attempt to achieve better surface passivation and reduce electronic defects which can limit performance. Optimization of this material led to improved open circuit voltage, exceeding 0.6 V for the first time, and record published performance of 6% efficiency. Using temperature-dependent and transient photovoltage measurements we explored the significance of interface recombination on the operation of these devices. Careful engineering of the electrode using atomic layer deposition of ZnO helped lead to better TiO2 substrate materials and allowed us to realize a nearly two-fold reduction in recombination rate and an enhancement upwards of 50 mV in open circuit voltage. Carrier extraction efficiency was studied in these devices using intensity dependent current-voltage data of an operational solar cell. By developing an analytical model to describe recombination loss within the active layer of the device we were able to accurately determine transport lengths ranging up to 90 nm. Transient absorption and photoconductivity techniques were used to study charge dynamics by identifying states in these quantum dot materials which facilitate carrier transport. Thermal activation energies for transport of 60 meV or lower were measured for different PbS quantum dot bandgaps, representing a relatively small barrier for carrier transport. From these measurements a dark, quantum confined energy level was attributed to the electronic bandedge of these materials which serves to govern their optoelectronic behavior.
Household Food Insecurity in Canada: Towards an Understanding of Effective Interventions
Keywords: food security
poverty
low income
family characteristics
material hardship
nutrition

Over 12% of households were food insecure in Canada in 2011. Despite recognition of this problem, there remains no targeted public policy to address it. To inform interventions, examined in this thesis were how changes in financial resources related to changes in severity of food insecurity, the needs of food insecure households, and the effectiveness of current interventions. Studies 1, 2, 4, and 5 utilized data from a sample of 485 low income families living in high poverty neighbourhoods in Toronto, and Study 3 used data from the Canadian Community Health Survey (CCHS) 2009-2011. In Study 1, the sensitivity of severity of food insecurity to changes in employment and income was observed. In Study 2, it was found that severity of food insecurity was associated with increasing probability of experiencing hardships in other domains such as delayed bill payments and giving up household services. The relationship between food insecurity and obesity among women was examined in Study 3, and it was shown that diagnoses of mood disorder partially explained the association. Patterns of association also varied by family status and severity of experiences. In Studies 4 and 5, use and non-use of current interventions focused on alleviating hunger (i.e. food banks) and improving healthy food access in communities (i.e. community gardens, Good Food Box) were examined among food insecure families. There was a low prevalence of use of all types of programs. Programs were not used because programs were not accessible or were not viewed as appropriate supports to meet needs. Taken together, findings suggest that interventions focused on potential manifestations and consequences of food insecurity are misplaced, and reinforce the urgent need for interventions to alleviate the financial insufficiency and insecurity that underpins food insecurity.
Cardiac Gating Methods for Coronary Magnetic Resonance Angiography
Keywords: Magnetic Resonance Imaging
Coronary Angiography
Cardiac Gating
Coronary Artery Disease

Coronary magnetic resonance angiography (CMRA) is a potential diagnostic tool for coronary artery disease (CAD). Compared to the current gold standard, x-ray angiography, CMRA provides three-dimensional visualization of coronary vessel lumens without the use of catheters and ionizing radiation. CMRA, however, requires long acquisition times that span multiple heartbeats. Typically, to reduce cardiac motion artifacts, electrocardiogram (ECG) gating is used to synchronize data acquisition windows to diastasis periods. Gating errors may cause vessel blurring by unintentionally triggering the scanner to acquire image data during periods of significant cardiac motion. This is particularly problematic for CMRA because of the associated fine spatial resolution requirement for diagnosing CAD. This thesis presents and tests the novel idea of determining the timing of global epicardial diastasis periods from the motion of the basal ventricular septum. An experiment involving a small patient cohort undergoing elective diagnostic angiography revealed a significant correlation between the beat-to-beat diastasis periods of the ventricular septum and the coronary vasculature. This motivated the ii development and testing of the hypothesis that suggests sharper coronary artery images may be obtained by using cardiac gating windows determined by septal motion. A preliminary study involving a small volunteer cohort provided encouraging results, but also revealed limitations of using ultrasound to measure septal motion during a pre- scan prior to an MRA exam. This led to the major technical development of this thesis, which is a magnetic resonance imaging (MRI) method called the Septal Scout for monitoring septal motion at a very high temporal resolution. The technique was applied to a volunteer cohort which showed that cardiac gating windows as determined by the Septal Scout provided sharper coronary images compared with conventional ECG gating. The scientific knowledge and technical developments presented in this thesis are intended to improve CMRA as a non-invasive diagnostic tool of CAD. In the future, I intend to integrate the concepts presented here into a functioning MRI-based cardiac gating system. As well, I intend to validate the Septal Scout in a patient cohort study.
The Impact of Technological Change within the Home
Keywords: Household technological change
Female labour force participation
Infant mortality

During the first two thirds of the 20th century, electricity, running water, and a host of new consumer durables diffused into most American homes. These new household technologies revolutionized domestic life by freeing up time from basic housework. In this dissertation, I study the consequences of household technological change on families, focusing on fertility, child health, marriage, and female labour force participation. Chapter 1 provides a short history of household modernization. I then present an econometric framework for evaluating the effects of household technological change, and discuss the main estimation challenges. To address these issues, I introduce an estimation strategy based on a newly-assembled dataset that captures the rollout of the U.S. power grid during the mid-20th century. In chapter 2, I study the impact of household technological change on fertility and child health, exploiting substantial cross-county and cross-state variation in the timing of when households acquired new consumer durables. Modern household technologies led families to make a child quantity-quality tradeoff favouring quality: household modernization is associated with decreases in infant mortality and decreases in fertility. The declines in infant mortality were particularly large in states where households had relied heavily on coal for heating and cooking, where the potential to improve indoor air quality was greatest. Health improvements were also larger in states that had previously invested heavily in maternal education, suggesting that household modernization led parents to provide better infant care. Overall, household technological change can account for between 25% and 30% of the total decline in infant mortality between 1930 and 1960. In chapter 3, I examine the relationship between household modernization, investment in children, and female employment. I present a conceptual framework in which household technological change has little immediate impact on female employment, but generates increased investment in daughters' human capital, ultimately causing a rise in employment for subsequent cohorts of women. I find empirical support for these predictions. Further, the results suggest that the diffusion of modern technology into the home during the first half of the 20th century can account for a significant fraction of the rise in female employment after 1950.
Mobilizing Collaborative Networks for a Transformative Food Politics: A Case Study of Provincial Food Networks in Canada
Keywords: transformative food politics
alterative food initiatives
social movement networks
politics of scale
community based research

In this dissertation I focus on the diversity of alternative food initiatives (AFIs) that have emerged amidst concerns about the corporate-led industrial food system. While there have been significant successes, critics suggest that many AFIs are an inadequate response to the complex problems within the food system, and further, are complicit in propagating neoliberal ideals and facilitating the retrenchment of the state. While these critics identify important challenges, they tend to consider place-based AFIs as operating independently on particular projects, with specific claims, or in isolated sectors of the food system. There has been little documentation or analysis situating AFIs within a broader community of practice. To fill this gap, my research builds on the existing literature to investigate the increasing collaborations among AFIs in Canada. Using a community-based action approach, I explore the development of provincial food networks in British Columbia, Manitoba, Ontario and Nova Scotia. I pay particular attention to efforts that foster and maintain these networks by exploring their history, structure and processes of collaboration. My findings reveal that the provincial food networks can be characterized as assemblages constituted by the self-organization of diverse actors through non-hierarchical, bottom-up processes with multiple and overlapping points of contact. Further, I find that AFIs have used networks strategically to contest the rules and institutions of the dominant food system and to develop participatory and democratic practices that challenge the logics of neoliberalism. Based on the results from this research, I argue that besides developing viable place-based alternatives to the dominant food system, AFIs are also involved in prefigurative ways of being - establishing democratic governance structures, building new institutions, and engaging in different kinds of social relations - in the belly of the existing (food) system.
Cocreating Value in Knowledge-intensive Business Services: An Empirically-grounded Design Framework and a Modelling Technique
Keywords: KIBS
service design
conceptual modeling
value cocreation

While knowledge-intensive business services (KIBS) play an important role in industrialized economies, little research has focused on how best to support their design. The emerging understanding of service as a process of value cocreation – or collaborative value creation – can provide the foundations for this purpose; however, this body of literature lacks empirically grounded explanations of how value is actually cocreated and does not provide adequate design support for the specific context of KIBS. This research thus first identifies generative mechanisms of value cocreation in KIBS engagements; it then develops a design framework from this understanding; finally, it elaborates a modeling technique fulfilling the requirements derived from this design framework. A multiple-case study of two academic research and development service engagements, as a particular type of KIBS engagement, was first undertaken to identify generative mechanisms of value cocreation. Data was gathered through interviews, observation, and documentation, and was analyzed both inductively and deductively according to key concepts of value cocreation proposed in literature. Data from a third case study was then used to evaluate the ability of the modeling technique to support the analysis of value cocreation processes in KIBS engagements. Empirical findings identify two contextual factors; one core mechanism; six direct mechanisms; four supporting mechanisms; and two overall processes of value cocreation, aligning and integrating. These findings emphasize the strategic nature of value cocreation in KIBS engagements. Results include an empirically grounded design framework that identifies points of intervention to foster value cocreation in KIBS engagements, and from which modeling requirements are derived. To fulfill these requirements, a modeling technique Value Cocreation Modeling 2 (VCM2) was created by adapting and combining concepts from several existing modeling approaches developed for strategic actors modeling, value network modeling, and business intelligence modeling.
Nonlinear Robust Control Synthesis Methods for Spacecraft Applications
Keywords: Nonlinear
Robust
Control
Spacecraft

This thesis focuses on practical methods for constructing robust nonlinear control systems. In general, the development of such control systems is characterized by the solution to one or more Hamilton-Jacobi partial differential equations (HJE). However, no general analytical solution has yet been obtained to solve this optimization problem. Solutions have thus far only been obtained under certain conditions. Therefore, the first significant contribution of this thesis is a method for obtaining analytical expressions for approximate solutions to a common form of HJE (under certain assumptions regarding the class of nonlinear systems used). Additionally, modern state space controller synthesis techniques typically result in state estimators of equal or greater dimension than the plant model. However, it is often desirable, or even necessary, to approximate these controllers by models of lower state dimension. Presently, methods for developing nonlinear state balancing transformations are not very well understood. Therefore, the second significant contribution of this thesis is a proper algorithm for the application of state balancing techniques to nonlinear control systems and the subsequent reduction of the number of control states. The method to be developed for state balancing is based on the above framework for constructing analytical solutions to the HJE. In this thesis we will make use of three existing robust nonlinear control methods from the literature. These three methods have the advantage that they can all be constructed from solutions to a single form of HJE. Thus, by developing a method for obtaining analytical expressions for the solution to a single form of HJE, we are able to develop explicit polynomial solutions for each of these three control methods. Due to the difficulties associated with quantifying robustness and performance properties for nonlinear systems, the effectiveness of the three control methods considered shall be demonstrated via numerical simulations. The particular applications of interest to us here are space systems. First, we will consider the attitude control of a single spacecraft. Second, we examine the problem of formation flying control for a pair of spacecraft. The third and final problem we consider is the control of a nonlinear mass-spring chain.
Analysis of Hemopoietic Malignancy in IgHm-TLX1TgPrkdcScid/Scid Mice
Keywords: Leukemia
cell biology
immunology
genetics

The non-cluster homeobox gene TLX1 was initially identified at the breakpoint of the t(10;14)(q24;q11) chromosome translocation in the malignant cells. Three independent research groups have generated transgenic mouse models expressing TLX1 in various hemopoietic cells resulting in development of B cell lymphoma and T-ALL. T-ALL tumours were characterized as immature Double Negative or/and Double Positive phenotypes. In addition, all TLX1 transgenic mice showed a long latency for leukemia development suggesting requirement of additional genomic abnormalities for the conversion of premalignant cells to full-blown malignancy. We hypothesized that unresolved double strand DNA breaks might act as additional genetic mutation and contribute to T-ALL progression in TLX1 overexpressed thymocytes. To address this hypothesis, we generated double mutant IgHμ-TLX1TgPrkdcScid/Scid mice, which accelerated the development of leukemia relative to PrkdcScid/Scid littermates. We identified that multiple genes associated with chromosome segregation, apoptosis and cell cycle progression were aberrantly expressed in IgHμ-TLX1TgPrkdcScid/Scid premalignant thymocytes. We found that IgHμ-TLX1TgPrkdcScid/Scid thymocytes were prone to chromosome instability suggesting malfunction of the mitotic spindle assembly checkpoint. In addition to T-ALL, 46% of IgHμ-TLX1TgPrkdcScid/Scid mice developed Acute Myeloid Leukemia, suggesting that the cancer initiating effects of TLX1 are not limited to cells of lymphoid origin. Transplantation experiments revealed that T cell acute lymphoblastic leukemia initiating cells (T-ALL-ICs) reside in the thymus of IgHμ-TLX1TgPrkdcScid/Scid mice and T-ALL-ICs were enriched in the c-kit+CD44+CD25- fraction. We showed that T-ALL tumour cells from IgHμ-TLX1TgPrkdcScid/Scid were transplantable and there was a tendency for the latency period of T-ALL development to be reduced with secondary and tertiary transplantations. We demonstrated that premalignant IgHμ-TLX1TgPrkdcScid/Scid myeloid progenitors exhibited deregulated apoptosis and proliferation. Collectively, our studies demonstrate that TLX1 expression in DNA-PK-deficient cells activats multiple oncogenic pathways leading to apoptosis resistance, accelerated proliferation and deregulation of the spindle assembly checkpoint. We propose that activation of the same pathways supporting survival and proliferation in various cells may be indicative of the universal principles driving TLX1-induced tumourogenesis. Our data provide clinically relevant information of the molecular mechanisms involved in the pathogenesis of leukemia that makes IgHμ-TLX1TgPrkdcScid/Scid mouse model a powerful tool to explore potential treatment options directed to delay disease progression.
Angiotensin II Proteomic Signature in Human Proximal Tubular Cells as a Predictor of Renin Angiotensin System Activity in Kidney Diseases
Keywords: kidney disease
angiotensin II
renin angiotensin system
proteomics
systems biology
SILAC method
biomarker
heme oxygenase 1

Angiotensin II (AngII), the major effector of the renin angiotensin system, mediates kidney disease progression by signalling through AT-1 receptor (AT-1R), but there are no specific measures of renal AngII activity. Accordingly, we sought to define an AngII-regulated proteome in primary human proximal tubular cells (PTEC) in order to identify potential AngII activity markers in the kidney. We utilized stable isotope labelling with amino acids (SILAC) in PTECs to compare proteomes of AngII-treated and control cells. Of 4618 quantified proteins, 83 were differentially regulated. SILAC ratios for 18 candidates were confirmed by Selected Reaction Monitoring (SRM) assays. Both SILAC and SRM revealed the nuclear factor erythroid 2-related 2 (Nrf2) target protein, heme oxygenase-1 (HO-1) as the most significantly upregulated protein in response to AngII stimulation. AngII-dependent regulation of HO-1 gene and protein was further verified by qRT-PCR and ELISA in PTECs. In order to extend these in vitro observations, we utilized a systems biology approach. We thus overlaid a network of significantly enriched gene ontology (GO) terms from our AngII-regulated proteins with a dataset of differentially expressed kidney genes from AngII-treated wild type mice and AT-1R knock-out mice. Five GO terms were enriched both in vitro and in vivo, and all included HO-1. Furthermore, four additional Nrf2 target proteins were functionally important in vitro and in vivo. We then studied HO-1 kidney expression and urinary excretion in AngII-treated wild type mice and mice with PTEC-specific AT-1R gene deletion. Deletion of the AT-1R gene in PTECs lowered both kidney expression and urine excretion of HO-1, confirming AngII/AT-1R mediated regulation of HO-1. In summary, our in vitro experiments identified novel molecular markers of AngII activity in PTECs and the animal studies demonstrated that these markers also reflect AngII activity in PTECs in vivo. These interesting proteins hold promise as specific markers of renal AngII activity in patients and in experimental models.
America's Search for Control in Iraq in the Early Cold War, 1953-1961
Keywords: US diplomatic History
US-Iraqi Relations

The United States emerged from the destruction of World War II a superpower with burgeoning global interests. Nowhere was this more evident than in Iraq. US policymakers greatly expanded their relationship with the pro-Western regime in Baghdad during the 1950s. To examine these trends more closely, this dissertation analyzes the American relationship with Iraq during the presidency of Dwight D. Eisenhower (1953 to 1961). This study discusses how American oil concessions, military aid programs, collective defense arrangements, and modernization initiatives shaped the US-Iraqi bilateral relationship of the 1950s. It also looks intensively at American intelligence assessments and covert action programs in Iraq in this period. An in-depth examination of the Eisenhower administration’s policies vis-à-vis Baghdad offers important lessons about the ways US officials understood and navigated complex political developments in the Middle East. In addition, this dissertation considers US strategies in Iraq in the context of ongoing developments in Egypt, Israel, Saudi Arabia, Turkey, Jordan, Iran, and elsewhere in the region. This transnational lens yields fascinating insights into how American interests throughout the Middle East influenced US policies in Iraq. As with their partners in the Iraqi government, American officials privileged the pursuit of “order” and “stability” in Baghdad. When confronted with the prospect of “unrest” in Iraq, the Eisenhower administration decisively supported its Iraqi allies’ moves to clamp down on political dissent. The United States worked energetically to control Iraqi developments in channels favourable to US interests. However, the regime led by Abdel Karim Qasim fundamentally transformed the patterns of the US-Iraqi relationship following the July 1958 Iraqi Revolution. Qasim’s program calling for the “Iraqification” of national economic resources collided with larger American understandings of Washington’s power in Baghdad. The Eisenhower administration proved unable to control the disorderly nature of revolutionary rule in Iraq, suggesting (as with the pre-revolutionary period) the tangible limits to American power in Iraq and the Middle East in this critical period of the Cold War.