VictorJuiz/thesis huggingface dataset:
Reconfigurable Transmitarray Antennas

Transmitarrays have been shown to be viable architectures for achieving high-directivity reconfigurable apertures. The existing work on reconfigurable transmitarrays is sparse, with only a few experimental demonstrations of reconfigurable implementations. Furthermore, of the designs that have been presented, different approaches have been proposed, but the advantages and drawbacks of these approaches have not been compared. Therefore, in this thesis we present a systematic study of the different approaches to designing reconfigurable transmitarrays, and present designs following these approaches with experimental validation. First, we investigate the distributed-scatterer approach, which is modeled with layers of identical scattering surfaces. We characterize the beamforming capabilities and then present a Method of Moments technique for analyzing and optimizing designs that follow this approach. Then, we present experimental results for a unit cell with varactor-loaded dipoles following this approach. From these results, we demonstrate that the structure thickness following this approach is problematic for beamforming applications. Taking the coupled-resonator approach, we next present a slot-coupled patch design that is significantly thinner and easier to fabricate than designs that follow the first approach. Implementing this design in a fully reconfigurable transmitarray, we demonstrate two-dimensional beamforming. An advantage of this design is that it can also operate as a reflectarray. Next, following the guided-wave approach, we present a transmitarray design that uses a bridged-T phase shifter and proximity-coupled differentially-fed stacked patches. Not only does this design not require vias, it is has a large fractional bandwidth of 10 percent, which is unprecedented in reconfigurable transmitarrays. Implementing this design in a full transmitarray, we experimentally demonstrate reconfigurable two-dimensional beamsteering, as well as shaped-beam synthesis. The main contributions of this thesis are two-fold. First, we thoroughly and systematically compare the transmitarray approaches, which has not been previously done in literature. Secondly, we experimentally demonstrate a reconfigurable array design that achieves better bandwidth, scan angle range, and beam-shaping capability, than existing designs, with reduced fabrication complexity and physical profile.

Keywords: Microwave antennas
Transmitarrays
Lens antennas
Reconfigurable Antennas
Advisor: Hum, Sean Victor
Seasonal Setting and the Human Domain in Early English and Early Scandinavian Literature

The contrast between the familiar social space and the world beyond has been widely recognised as an organising principle in medieval literature, in which the natural and the supernatural alike are set off against human society as alien and hostile. However, the study of this antithesis has typically been restricted to the spatial aspect whereas the literature often exhibits seasonal patterns as well. This dissertation modifies the existing paradigm to accommodate the temporal dimension, demonstrating that winter stands out as a season in which the autonomy of the human domain is drawn into question in both Anglo-Saxon and early Scandinavian literature. In Old English poetry, winter is invoked as a landscape category connoting personal affliction and hostility, but it is rarely used to evoke a cyclical chronology. Old Icelandic literature likewise employs winter as a spatial category, here closely associated with the dangerous supernatural. However, Old Icelandic prose furthermore give winter a place in the annual progression of the seasons, which structures all but the most legendary of the sagas. Accordingly, the winter halfyear stands out as the near-exclusive domain of revenant hauntings and prophecy. These findings stand in stark contrast to the state of affairs in Middle English poetry, which associates diverse kinds of adventure and supernatural interaction with florid landscapes of spring and summer, and Maytime forests in particular. Even so, the seasonal imagery in <em>Sir Gawain and the Green Knight</em> makes clear that Middle English poets could use the contrastive functions of winter to no less effect than authors in neighbouring corpora. In partial explanation of authorial choices in this regard, it is proposed that winter settings are employed especially where a strong empathic response is desired of the audience.

Keywords: Old English
Old Norse
Middle English
Latin
Anglo-Saxon
ecocriticism
landscape
season
Beowulf
Grettis saga
Gawain
Advisor: Orchard, Andy
Topics in Canadian Aboriginal Earnings, Employment and Education: An Empirical Analysis

This dissertation is divided into three main components that each relate to the socioeconomic wellbeing of Aboriginal peoples in the Canadian labour market. Specifically, using data from the master file of the Canadian census for the years 1996, 2001 and 2006, the first section examines the wage differential for various Aboriginal and non-Aboriginal groups, including a comparison of those living on-and-off-reserves. The study finds that, while a sizeable wage gap between Aboriginal and non-Aboriginal persons still exists, this disparity has narrowed over the three census periods for those living off-reserve. The Aboriginal-non-Aboriginal wage differential is largest among the on-reserve population and this gap has remained relatively constant over the three census periods considered in the study. The second study in the dissertation uses data from the master file of the Canadian Labour Force Survey for 2008 and 2009 to estimate the probability that an individual is a labour force participant, and, conditional on labour force participation, the probability that a respondent is unemployed, comparing several Aboriginal and non-Aboriginal groups. The results reveal that Aboriginal men and women have lower rates of labour force participation and higher rates or unemployment in both periods as compared to their non-Aboriginal counterparts. Aboriginal peoples were also disproportionately burdened by a slowdown in economic activity as measured by a change in the probability of unemployment moving from 2008 to 2009, as compared to non-Aboriginal people, who experienced a smaller increase in the probability of unemployment moving from a period of positive to negative economic growth. Finally, the third study examines the probability of high school dropout comparing Aboriginal peoples living on-and-off-reserve using data from the master file of the Aboriginal Peoples Survey for 2001. The findings reveal dramatically higher rates of dropout among Aboriginal people living on-reserve as compared to those living off-reserve. Limitations of all three studies as well as some possible directions of future research related to similar issues concerning Canada’s Aboriginal population are discussed in the concluding chapter of the dissertation.

Keywords: Earnings
Employment
Unemployment
Labour Force Activity
Aboriginal Peoples
Education
Advisor: Gunderson, Morley
Interactions of L. monocytogenes with Host Cellular Defenses

Listeria monocytogenes is an intracellular bacterium that utilizes two phospholipases C (PLCs) and a pore-forming cytolysin (listeriolysin O, LLO) to escape the phagosome. However, prior to escape, the bacterium must overcome a number of phagosomal defenses, including autophagy and NOX2 NADPH oxidase production of reactive oxygen species (ROS). Autophagy, the cellular process of self-digestion, is a key component of innate immunity. Previously, it has been shown that L. monocytogenes is targeted by autophagy (LC3+) at 1 h post infection (p.i.) but the mechanism remains elusive. Here, I show that at 1 h p.i., diacylglycerol (DAG) and ROS production are required for autophagy targeting to the bacteria, which are predominantly in phagosomes. It has been shown that autophagy targeting of cytosolic L. monocytogenes is mediated via protein ubiquitination. However, protein ubiquitination is not associated with LC3+ bacteria at 1 h p.i.. Thus, my data suggest that distinct signals mediate autophagy targeting of L. monocytogenes depending on the location within host cells. Given that ROS mediate autophagy targeting to L. monocytogenes and that previous studies have demonstrated that ROS production limits bacterial escape, I investigated how L. monocytogenes overcomes ROS production prior to phagosomal escape. I found that LLO inhibits ROS production by preventing NOX2 NADPH oxidase localization to L. monocytogenes-containing phagosomes. LLO-deficient bacteria can be complemented by perfringolysin O, a related cytolysin, suggesting that other pathogens may also use pore-forming cytolysins to inhibit ROS production. While PLCs can activate ROS production, this effect is alleviated by LLO pore-formation. Therefore, the combined activities of PLCs and LLO allow L. monocytogenes to efficiently escape the phagosome while avoiding microbicidal ROS. Together, this thesis provides a clearer understanding of the balance between host defense versus bacterial evasion. Greater insight into host-bacterial interaction may lead to better therapeutics that can “tip the balance” in the host’s favour.

Keywords: L. monocytogenes
Reactive oxygen species
Autophagy
Bacterial Host Interaction
Advisor: Brumell, John
Applications of α-Keto Carbocations in Carbon-Carbon and Carbon-Nitrogen Bond Formation

This thesis describes synthetic applications of α-keto carbocations, which represent potentially useful, but poorly studied, reversed polarity equivalents of enolates. In the first chapter, a Ag(I) – mediated method for the nucleophilic displacement of α-halocarbonyl compounds to construct carbon-carbon bonds is described. The highly electrophilic nature of the putative α-keto carbocation intermediates enables the use of relatively unreactive nucleophiles in both intra- and intermolecular contexts. Such intermediates also present interesting opportunities for stereocontrol: our efforts to carry out diastereoselective additions to chiral α-keto carbocations are described. Oxazoles are an important class of heterocycles, and several syntheses are addressed in Chapter 2. Our approach to this class of compounds employs a TMSOTf mediated Ritter reaction to construct the carbon-nitrogen bond. Cycloaddition of 2-alkoxyoxazoles with alkynes presents a facile route for furan synthesis. The final chapter describes our attempts to apply anion-π interaction in organocatalysis. These interactions between anions and electron-deficient arenes have been characterized in some detail and have recently been applied in ion transport. Applications of prolinol-based secondary amines incorporating electron-deficient aromatic groups are described.

Keywords: carbocation
stereoselectivity
Advisor: Taylor, Mark S.
Interactions of TCAP-1 and Endocannabinoids with Corticotropin-releasing Factor in Mediating Cocaine- and Anxiety-related Behaviour

The neuropeptide, corticotropin-releasing factor (CRF), plays a critical role in the central regulation of various stress-related behaviours, including those unique to subjects with prior cocaine experience. The three series of experiments presented in this dissertation explored the role of two neurochemical systems, the teneurin C-terminal associated peptides (TCAP) and the endocannabinoids (eCBs), in several cocaine- and anxiety-related behaviours induced or mediated by CRF. The first series of experiments examined the effects of TCAP-1 on the reinstatement of cocaine seeking and expression of cocaine-induced behavioural sensitization. Repeated (5-day), but not acute, TCAP-1 treatment blocked the reinstatement of cocaine seeking induced by central injections of CRF. TCAP-1 was, however, without effect on footshock- or cocaine-induced reinstatement. Repeated TCAP-1 further interfered with the expression of behavioural sensitization to a CRF, but not a cocaine, challenge. These findings suggest that TCAP-1 normalizes CRF signaling dysregulated by cocaine exposure to interfere in the subsequent effects of CRF on cocaine-related behaviours. A parallel series of experiments investigated the role of eCB signaling at CB1 receptors in the reinstatement of cocaine seeking and cocaine-sensitized locomotion. Pretreatment with the CB1 receptor antagonist, AM251, selectively interfered with CRF-, but not footshock- or cocaine-induced reinstatement. AM251 further blocked the expression of behavioural sensitization induced by challenge injections of both CRF and cocaine. These findings reveal a mediating role for CB1 receptor transmission in the effects of CRF on cocaine-related behaviours. A final series of experiments examined the role of CB1 receptor transmission in the behavioural anxiety induced by central injections of CRF, and by withdrawal from chronic cocaine exposure. AM251, although itself anxiogenic, reversed anxiety induced by CRF and cocaine withdrawal. Furthermore, AM251 elevated plasma corticosterone levels, indicative of increased HPA axis activity, irrespective of CRF treatment or cocaine withdrawal. These findings suggest that CRF- and cocaine withdrawal-induced anxiety are mediated, at least in part, by CB1 receptor transmission, independent of HPA axis regulation. The collective findings are discussed within a framework of CRF-TCAP-eCB interactions, wherein TCAP-1 and AM251 are proposed to act in parallel to modulate amygdalar CRF transmission, and thus regulate the expression of cocaine- and anxiety-related behaviours.

Keywords: CRF
Corticotropin
TCAP
Teneurin
Endocannabinoid
Canabinoid
Cocaine
Reinstatement
Sensitization
Anxiety
Advisor: Erb, Suzanne
Holistic Health and the Prevention of Performance-related Musculoskeletal Disorders in Orchestral String Musicians

Professional orchestral string musicians represent a population at risk for performance-related musculoskeletal disorders (PRMD). Research literature suggests the influence of stress in the incidence of work-related and performance-related musculoskeletal disorders. The purpose of this study was to qualitatively investigate the role of holistic health (physical, mental, emotional, spiritual, and social) and stress management in the prevention of PRMDs in professional orchestral string musicians. Five musicians representing different instruments, genders, and PRMD histories were recruited and sorted from a single professional orchestra in Canada. This study combined quantitative data - in the form of basic demographic information and a Health and Well-being Assessment - with qualitative interview data. This combined data provided a focused, in-depth view of typical instances in the professional orchestral string population. The musicians reported a variety of occupational and non-occupational risk factors, as well as a range of intrinsic risk factors. They also reported a variety of PRMD prevention strategies and lifestyle behaviours. The musicians in this study provide evidence that stress may play a mediating role in PRMDs and that the management of biomechanical and psychosocial stressors through holistic health practices may positively influence the incidence, severity, and treatment of PRMDs in orchestral string musicians. This dissertation recommends that increased awareness and education in holistic health practices be encouraged for the purpose of improved PRMD prevention in professional orchestral string musicians.

Keywords: injury prevention
musicians
performance-related musculoskeletal disorders
performance-related injuries
holistic health
well-being
orchestral
string
stress management
occupational health
music
orchestra
musicians
injury
performing arts health
Advisor: Parker, James
A Study of Electrogenic Transient and Steady-state Cotransporter Kinetics: Investigations with the Na+/Glucose Transporter SGLT1

Significant advancements in the field of membrane protein crystallography have provided in recent years invaluable images of transporter structures. These structures, however, are static and require complementary kinetic insight to understand how their mechanisms work. Electrophysiological studies of transporters permit the high quality kinetic measurements desired, but there are significant difficulties involved in analyzing and interpreting the data. Current methods allow a variety of kinetic parameters to be measured but there is a disconnect between these parameters and a fundamental understanding of the carrier. The intent of this research was to contribute new tools for studying the electrogenic kinetics of membrane transport proteins, to understand the link between these kinetics and the carrier, and to ultimately understand the mechanisms involved in transport. In this vein, two projects are explored covering two important kinetic time domains, transient and steady-state. The transient project studies the conformational changes of the unloaded carrier of SGLT1 through a multi-exponential analysis of the transient currents. Crystal structures have potentially identified a gated rocker-switch mechanism and the transient kinetics are used to support and study this kinetically. A protocol taking advantage of multiple holding potentials is used to measure the decay time constants and charge movements for voltage jumps from both hyperpolarizing and depolarizing directions. These directional measurements provide insight into the arrangement of the observed transitions through directional inequalities in charge movement, by considering the potential for a slow transition to hide a faster one. Ultimately, four carrier decays are observed that align with the gated rocker-switch mechanism and can be associated one-to-one with the movement of a gate and pore on each side of the membrane. The steady-state project considers a general theoretical model of transporter cycling. Recursive patterns are identified in the steady-state velocity equation that lead to a broad understanding of its geometric properties as a function of voltage and substrate concentration. This results in a simple phenomenological method for characterizing the I–V curves and for measuring the kinetics of rate limiting patterns in the loop, which we find are the basic structures revealed by the steady-state velocity.

Keywords: membrane transport
electrophysiology
enzyme kinetics
two-electrode voltage-clamp
SGLT1
Advisor: Silverman, Mel
Bayesian Hidden Markov Models for finding DNA Copy Number Changes from SNP Genotyping Arrays

DNA copy number variations (CNVs), which involve the deletion or duplication of subchromosomal segments of the genome, have become a focus of genetics research. This dissertation develops Bayesian HMMs for finding CNVs from single nucleotide polymorphism (SNP) arrays. A Bayesian framework to reconstruct the DNA copy number sequence from the observed sequence of SNP array measurements is proposed. A Markov chain Monte Carlo (MCMC) algorithm, with a forward-backward stochastic algorithm for sampling DNA copy number sequences, is developed for estimating model parameters. Numerous versions of Bayesian HMMs are explored, including a discrete-time model and different models for the instantaneous transition rates of change among copy number states of a continuous-time HMM. The most general model proposed makes no restrictions and assumes the rate of transition depends on the current state, whereas the nested model fixes some of these rates by assuming that the rate of transition is independent of the current state. Each model is assessed using a subset of the HapMap data. More general parameterizations of the transition intensity matrix of the continuous-time Markov process produced more accurate inference with respect to the length of CNV regions. The observed SNP array measurements are assumed to be stochastic with distribution determined by the underlying DNA copy number. Copy-number-specific distributions, including a non-symmetric distribution for the 0-copy state (homozygous deletions) and mixture distributions for 2-copy state (normal), are developed and shown to be more appropriate than existing implementations which lead to biologically implausible results. Compared to existing HMMs for SNP array data, this approach is more flexible in that model parameters are estimated from the data rather than set to a priori values. Measures of uncertainty, computed as simulation-based probabilities, can be determined for putative CNVs detected by the HMM. Finally, the dissertation concludes with a discussion of future work, with special attention given to model extensions for multiple sample analysis and family trio data.

Keywords: DNA copy number
Bayesian HMM
SNP array
Advisor: Kustra, Rafal
Nurses' Ethical Problem Solving

A growing body of research has drawn attention to the hierarchical and bureaucratic nature of the hospital organizational environment in which nurses seek to resolve ethical problems related to patient care, whereas other studies have focused on the impact of nurses’ personal or professional qualities on those nurses’ ethical problem solving. This qualitative investigation sought to elucidate the extent to which nurses perceived their personal or professional qualities, as well as organizational characteristics, as influencing their ethical decision making. This investigator interviewed 10 registered nurses in 2 acute-care hospitals that were different in size, location, and type. A relational ethics lens assisted in the analysis of the data, emphasizing ways in which the nurses’ ethical problem solving was socially situated within a complex of relationships with others, including patients, families, physicians, and coworkers. Data analysis revealed key themes, including the nurses’ concern for patients, professional experience, layered relationships with others, interactions within the organization, and situational analysis of contexts and relationships. Subthemes included the nurses’ relationships with patients, physicians, patients’ families, and coworkers. This study revealed a range of ethical problems. Nurses saw their patients as their greatest concern; the nurses worked within a social context of multilayered and complex relationships within a hierarchical, bureaucratic organization with the desire to bring about the best outcomes for patients. The participants described ethical concerns related to the actions or decisions of physicians, patients’ family members, and nurses’ coworkers. The nurses’ deliberation to resolve these ethical problems considered risks and benefits for patients, nurses, and others. The nurses seemed to carry out a contextual assessment, analyzing the presence of mutual respect, the extent of relational engagement, and the potential for opening relational space in order to work together with others to resolve the ethical problem for the patient’s best outcome. The nurses’ ethical actions were socially situated within this complex interpersonal context. This thesis discusses implications of these findings for nursing research, education, and practice.

Keywords: nursing
ethics
problem solving
Advisor: Bascia, Nina