VictorJuiz/thesis huggingface dataset:
Food, Eating and the Body: An Account of Women's Lived Experiences Across the Lifespan

The purpose of this study was to explore women’s subjective food and eating experiences from childhood through to adulthood and the ways in which these experiences either connected or disconnected them from their appetites for food and eating. The present study used a qualitative life history methodology, the goal of which is to assess individuals’ lived experiences to construct broader contextual meaning. In-depth interviews were used to investigate food and eating experiences among twelve women between ages 25 and 44, representing diverse social and cultural backgrounds as well as current and past eating problems. Participants took part in an open-ended interview, using a series of guided questions about their food and eating experiences from childhood through to adulthood. The interviews were transcribed and analyzed for themes using the constant comparison method. Two models emerged from the data in this study that described the social factors that connected and disconnected women from their appetites and eating. The Regulating Discourses Model which outlines current ways women negotiate appetite and desire through food and eating experiences, and the Socialization through Food and Eating Model which delineates socialization processes related to food and eating during women’s development. This research may be useful for counselors, health care professionals, as well as the larger community to increase awareness on ways to maintain girls’ and women’s connection to their bodily appetites and desires throughout the lifespan.

Keywords: hunger, appetite
eating experiences
Advisor: Piran, Niva
Functional Analysis of the Thiol Oxidoreductase ERp57 and its Role in the Biogenesis of MHC Class I Molecules

Class I major histocompatibility complex molecules present antigenic peptides to cytotoxic T lymphocytes, which leads to the elimination of virus infected cells. Class I molecules are heterotrimers consisting of a heavy chain, a light chain termed beta2-microglobulin, and a peptide ligand. Assembly of class I molecules begins in the endoplasmic reticulum where the heavy chain associates with beta2-microglobulin, and the heavy chain-beta2-microglobulin heterodimers enter a peptide loading complex where class I molecules acquire peptides. During the biogenesis of class I molecules, ERp57, a thiol oxidoreductase, associates with free class I heavy chains and, at a later stage, with the peptide loading complex. In this thesis, I show for the first time that ERp57 participates in oxidative folding of the heavy chain. Depletion of ERp57 by RNAi delayed heavy chain disulfide bond formation and slowed folding of the heavy chain alpha3 domain. Interestingly, depletion of another thiol oxidoreductase, ERp72, had no such effect. Since ERp57 associates with the lectin-chaperones calnexin and calreticulin, it is thought that ERp57 requires these chaperones to gain access to its substrates. To test this idea, I examined class I biogenesis in cells lacking calnexin or calreticulin or that express an ERp57 mutant that fails to bind to these chaperones. Remarkably, heavy chain disulfides formed at the same rate in these cells as in wild type cells, suggesting that ERp57 has the capacity to recognize its substrates directly in addition to being recruited through lectin-chaperones. ERp57 also forms a mixed disulfide with tapasin within the peptide loading complex and I found that the formation of this mixed disulfide is independent of its interaction with calnexin and calreticulin. I also found that calreticulin could be recruited into the peptide loading complex in the absence of interactions with both ERp57 and substrate oligosaccharides, demonstrating the importance of its polypeptide-binding site in substrate recognition. Finally, by inactivating the redox active sites of ERp57, I demonstrate that its enzymatic activity is dispensable in stabilizing the loading complex and in supporting efficient peptide loading. Thus, ERp57 plays a structural rather than catalytic role within the peptide loading complex.

Keywords: protein folding
thiol oxidoreductase
ERp57
major histocompatibility complex
antigen presentation
Advisor: Williams, David
Numerical Modeling of Active Hydraulic Devices and Their Significance for System Performance and Transient Protection

The thesis numerically explores the use and behavior of Active Hydraulic Devices (AHDs), creating a new capability to simulate and control a pipe system’s transient performance. Automatic control valves are the first type of AHDs studied in this research. Due to the challenges inherent in the design of a pressure relief valve (PRV), the general principles of PRV use and selection are studied along with the system’s response to the PRV parameters. A new application of PID (proportional, integral and derivative) control valve is envisioned that combines a remote sensor at the upstream end of a pipeline to create a non- or semi- reflective boundary at the downstream end. Case studies show that, with such a boundary, the reflection and resonance of pressure waves within the pipeline are sometimes eliminated and invariably limited. The second type of AHDs studied in this research is the governed hydro turbine, the most complicated hydraulic component in terms of transient analysis and waterhammer control. A complete numerical model is developed for the turbine installations in either urban water networks or conventional hydropower generation systems. Using the model, transient simulations for several realistic hydro projects are presented along with various transient control measures.

Keywords: Active Hydraulic Device
Hydro Turbine
Non-Reflective Boundary
Transient
Advisor: Karney, Bryan William
Unemployment Insurance Eligibility and the Dynamics of the Labor Market

This thesis examines a number of issues regarding the Mortensen-Pissarides search and matching model’s empirical performance. Chapter 1 documents the volatility puzzle with the Canadian data. The combined data from both Canada and the United States present an additional difficulty. Even if the unobserved value of leisure is allowed to be as high as required to fit the business cycle in the United States or in Canada, the model cannot reconcile the similar labor cycles with the large policy differences in the UI benefits and income taxes in the two countries when the value of leisure is assumed to be the same in both countries. Chapter 2 takes into account the realistic institutional features of the UI system and investigates the impacts of the UI benefits on the labor market outcomes. If entitlement to UI benefits must be earned with employment, generous UI is an additional benefit to an employment relationship, so it promotes job creation. If individuals are risk neutral, UI is fairly priced, and the UI system prevents moral-hazard unemployed workers, the generosity of UI has no effect on unemployment. Chapter 3 shows that the Mortensen-Pissarides search and matching model can be successfully parameterized to generate observed large cyclical fluctuations in unemployment and modest responses of unemployment to changes in the UI benefits. The key features behind this success are the endogenous eligibility for UI benefits and the heterogeneity of workers. With the linear utilities commonly assumed in the Mortensen-Pissarides model, a fully rated UI system designed to prevent moral hazard has no effect on unemployment. However, the UI system in the United States is neither fully rated nor able to prevent workers with low productivity from quitting their jobs or rejecting employment offers to collect benefits. As a result, an increase in UI generosity has a positive, but realistically small, effect on unemployment. This chapter answers the Costain and Reiter (2008) criticism with the Mortensen-Pissarides model.

Keywords: Unemployment Insurance Eligibility, Dynamics, Labor Market, Equilibrium Unemployment, Moral Hazard
Advisor: Faig, Miquel
Bioelectric Source Localization in Peripheral Nerves

Currently there does not exist a type of peripheral nerve interface that adequately combines spatial selectivity, spatial coverage and low invasiveness. In order to address this lack, we investigated the application of bioelectric source localization algorithms, adapted from electroencephalography/magnetoencephalography, to recordings from a 56-contact “matrix” nerve cuff electrode. If successful, this strategy would enable us to improve current neuroprostheses and conduct more detailed investigations of neural control systems. Using forward field similarities, we first developed a method to reduce the number of unnecessary variables in the inverse problem, and in doing so obtained an upper bound on the spatial resolution. Next, a simulation study of the peripheral nerve source localization problem revealed that the method is unlikely to work unless noise is very low and a very accurate model of the nerve is available. Under more realistic conditions, the method had localization errors in the 140 μm-180 μm range, high numbers of spurious pathways, and low resolution. On the other hand, the simulations also showed that imposing physiologically meaningful constraints on the solution can reduce the number of spurious pathways. Both the influence of the constraints and the importance of the model accuracy were validated experimentally using recordings from rat sciatic nerves. Unfortunately, neither idealized models nor models based on nerve sample cross-sections were sufficiently accurate to allow reliable identification of the branches stimulated during the experiments. To overcome this problem, an experimental leadfield was constructed using training data, thereby eliminating the dependence on anatomical models. This new strategy was successful in identifying single-branch cases, but not multi-branches ones. Lastly, an examination of the information contained in the matrix cuff recordings was performed in comparison to a single-ring configuration of contacts. The matrix cuff was able to achieve better fascicle discrimination due to its ability to select among the most informative locations around the nerve. These findings suggest that nerve cuff-based neuroprosthetic applications would benefit from implanting devices with a large number of contacts, then performing a contact selection procedure. Conditions that must be met before source localization approaches can be applied in practice to peripheral nerves were also discussed.

Keywords: Neural interfaces
Source localization
Peripheral nerves
Nerve cuff electrodes
Neuroprostheses
Advisor: Popovic, Milos R.
FPGA-based Soft Vector Processors

FPGAs are increasingly used to implement embedded digital systems because of their low time-to-market and low costs compared to integrated circuit design, as well as their superior performance and area over a general purpose microprocessor. However, the hardware design necessary to achieve this superior performance and area is very difficult to perform causing long design times and preventing wide-spread adoption of FPGA technology. The amount of hardware design can be reduced by employing a microprocessor for less-critical computation in the system. Often this microprocessor is implemented using the FPGA reprogrammable fabric as a soft processor which can preserve the benefits of a single-chip FPGA solution without specializing the device with dedicated hard processors. Current soft processors have simple architectures that provide performance adequate for only the least-critical computations. Our goal is to improve soft processors by scaling their performance and expanding their suitability to more critical computation. To this end we focus on the data parallelism found in many embedded applications and propose that soft processors be augmented with vector extensions to exploit this parallelism. We support this proposal through experimentation with a parameterized soft vector processor called VESPA (Vector Extended Soft Processor Architecture) which is designed, implemented, and evaluated on real FPGA hardware. The scalability of VESPA combined with several other architectural parameters can be used to finely span a large design space and derive a custom architecture for exactly matching the needs of an application. Such customization is a key advantage for soft processors since their architectures can be easily reconfigured by the end-user. Specifically, customizations can be made to the pipeline, functional units, and memory system within VESPA. In addition, general purpose overheads can be automatically eliminated from VESPA. Comparing VESPA to manual hardware design, we observe a 13x speed advantage for hardware over our fastest VESPA, though this is significantly less than the 500x speed advantage over scalar soft processors. The performance-per-area of VESPA is also observed to be significantly higher than a scalar soft processor suggesting that the addition of vector extensions makes more efficient use of silicon area for data parallel workloads.

Keywords: soft processor
soft Vector processor
FPGA
custom
embedded
SIMD
data parallel
Advisor: Rose, Jonathan S.
Steffan, J. Gregory
Characterization of the tmRNA Tagging System in Streptomyces coelicolor

The ssrA gene encoded tmRNA acts as both a tRNA carrying an Ala to enter the A site of stalled ribosomes and as an mRNA allowing trans-translation to continue until ribosomes reach the stop codon of the tmRNA tag to help release the stalled ribosome, label the truncated peptide for degradation, and also facilitate degradation of the ribosome-stalling mRNAs. Functions of tmRNA rely on its binding to an essential protein factor SmpB that is encoded by the smpB gene. The mycelial bacteria streptomycetes have a well-defined growth and developmental cycle culminating at sporulation and provide a good model to study tmRNA function in bacteria growth and development. During different developmental stages, expression of some critical molecules are increased or decreased to control the developing procedures including a bldA-encoded tRNA that decodes the rare codon UUA. Translation elongation of genes containing UUA rare codons may be stalled and elicits tmRNA tagging, suggesting that tmRNA the tagging system may be important for Streptomyces growth and development. We use the most well studied strain, S. coelicolor whose genome sequence was the first sequenced, as our model organism. Here I report my ssrA knockout study with two different strategies. Using a temperature sensitive replicon, I found that the ssrA gene could be disrupted only in cells with an extra ssrA gene but not in wild type cells or cells with an extra-copy of tmRNA variant--tmRNADD that encodes a degradation-resistant tag. These results imply that ssrA is an essential gene and that degradation of truncated proteins is also an essential function for S. coelicolor. On the contrary, with the second method that does not need high temperature screening steps I was able to disrupt both the ssrA and smpB genes separately and at the same time, suggesting that the tmRNA tagging system may be required for cell survival under high temperature. Further characterization of mutant cells revealed that the tmRNA tagging system is important for cell growth and development at both high temperature and optimal growth conditions as well as under stress conditions that affect the translation elongation process. The second part of my thesis documents analyses of the expression, regulation and stability of S. coelicolor tmRNA. My results suggested that the well known metabolic stability of bacterial tmRNA might be due to its tight binding to the ribosome. Finally, I report my investigation of the tagging activity and the importance of some structural elements of S. coelicolor tmRNA. Particularly, I demonstrated that pseudoknot 4 is important for tmRNA tagging activity and mutations to some structural elements lead to a decrease of not only the mutant tmRNA but also the wild type tmRNA when expressed together in vivo.

Keywords: tmRNA
Streptomyces
translation
antibiotics
Advisor: Glover, John R.
Starting and Staying on Course: Influences of Pre-service and Initial Placement on Beginning Teachers

In this thesis I consider experiences of two beginning teachers during their pre-service year at the Faculty of Education at the University of Toronto and the early years of their teaching careers as they move from student teacher to professional teacher. In particular, I use narratives I created about each woman along with my own to identify the factors which influenced the success of this transition such as the nature of the first teaching positions held, the types of supports and assistance experienced during this transitional phase, and the personal experiences brought to the enterprise of becoming a teacher. Additionally, I look for any changes in their beliefs about teaching from those held as teacher-candidates to those that evolved during the initial years in the classroom and what influence, if any, these professional environments had on such shifts in thinking. In this study I use a narrative inquiry approach in which my own story is placed along side those of my two participants. By doing so, I acknowledge the close relationship between the primary investigator and the study subjects that is inherent in this qualitative method. My data sources for the narratives I created include written material in the form of journals, interview transcripts, practice teaching reports, and personal narratives produced by and about my participants during the time under study. In my concluding chapter, I make suggestions for changes both to the ways in which teacher-candidates are instructed as they begin to learn the intricacies of the art of teaching and to the conditions under which many of these new members of the profession begin their careers. There are many avenues for future research that I did not pursue in this study and some of these are outlined in my conclusions.

Keywords: Teacher Training
Advisor: Aitken, Johan Lyall
Colonic Fermentation, Equol Status and the Hypocholesterolemic Effect of Soy

Background: The value of soy, as an effective component of a cholesterol lowering diet, is currently questioned due to smaller lipid reductions than previously reported for the currently approved US FDA health claim for soy. Nevertheless, intrinsic and extrinsic factors may exist that influence the effectiveness of soy, but little research has been done in this area. Such factors include the soy isoflavone content, dietary components that alter colonic fermentation and the colon’s ability to biotransform isoflavones (i.e. equol status). Objective: To determine if specific factors, such as dose of soy isoflavones and those that alter colonic fermentation, influence the hypocholesterolemic effect of soy. Furthermore, whether cholesterol reductions differ depending on the interindividual variation in isoflavone biotransformation (i.e. equol status), when soy is consumed under different dietary conditions (i.e. with specific factors). Methods: 85 men and postmenopausal women (42M, 43F) with hyperlipidemia participated in one of three substudies where soy foods, containing 30-52g/d of soy protein, were provided over a one-month period under the following conditions: 1) high-normal (73mg/d) or low (10mg/d) soy isoflavones (N=41); 2) with or without a prebiotic (10g/d polyfructans) to increase colonic fermentation (N=22); or 3) with a reduced carbohydrate diet (26% of calories) to decrease colonic fermentation (N=22). Results: Unmodified soy foods significantly reduced LDL-C by 5.1%±2.0% (P=0.016). LDL-C reductions were not altered with increased soy isoflavone content nor were the effects dampened with reduced carbohydrate. However, coingestion of soy with a prebiotic improved the cholesterol lowering effect of soy. Equol producers (N=30) showed a relative increase of 5.3±2.5% in HDL-C (P=0.035) after soy compared to nonproducers (N=55), but no significant differences were observed for LDL-C or other lipids. Equol excretion was increased with increased soy isoflavone content, but not with the addition of a prebiotic. Conclusion: The effectiveness of soy, as a cholesterol lowering food, may be improved with the addition of prebiotics, but not with decreased carbohydrate or increased isoflavones. Equol status appears to alter the HDL-C, but not the LDL-C response. These data support the continued use of soy foods as part of the dietary approach to coronary heart disease risk reduction.

Keywords: Nutrition
Advisor: Jenkins, David J. A.
A Diagrammatic Description of Tensor Product Decompositions for SU(3)

The direct sum decomposition of tensor products for SU(3) has many applications in physics, and the problem has been studied extensively. This has resulted in many decomposition methods, each with its advantages and disadvantages. The description given here is geometric in nature and it describes both the constituents of the direct sum and their multiplicities. In addition to providing decompositions of specific tensor products, this approach is very well suited to studying tensor products as the parameters vary, and drawing general conclusions. After a description and proof of the method, several applications are discussed and proved. The decompositions are also studied further for the special cases of tensor products of an irreducible representation with itself or with its conjugate. In particular, questions regarding multiplicities are considered. As an extension of this diagrammatic method, the repeated tensor product of N copies of the fundamental representation is studied, and a method for its decomposition is provided. Again, questions regarding multiplicities are considered.

Keywords: Lie algebras
Representations
Tensor product decompositions
Decomposition method
Tensor diagrams
Multiplicities
Advisor: Repka, Joseph
An Investigation of the Associations among Recovery, Key Illness Characteristics and Bone Mineral Density in Women with a History of Anorexia Nervosa

Background: Reduced bone mineral density (BMD) is an established complication of anorexia nervosa (AN). There is inconclusive evidence as to whether this reduction in bone mass is permanent or can be reversed with recovery from AN. The objectives of this study were to: i. determine the extent of reversal of skeletal deficits with recovery from AN, and the duration of recovery required for complete reversal, if this occurred; and, ii. evaluate the effect of key illness characteristics on BMD. Methods: Women (aged 17-40 years) who had previously received inpatient treatment for AN at one of two hospital-based programs were selected for this cross-sectional study; 514 healthy premenopausal women recruited from the community served as a control group. A detailed lifetime illness history was obtained by a Life History Calendar interview. BMD was measured by dual-energy X-ray absorptiometry (DXA) at the spine, hip and total body. Low BMD was defined as a weight and age-matched standard deviation (Z-score) of ≤ -1.5 at one or more skeletal sites. Participants were considered recovered if they had maintained a body mass index ≥ 18.5 kg/m2 and resumed regular menstruation for ≥ 1 year. Results: Of 190 AN participants, 77 were considered recovered and 113 were ill. The prevalence of low BMD was 11.7% in the recovered group, 47.3% in the ill group and 6.8% in the control group. The odds of low BMD in the recovered participants was significantly lower than in the ill participants (odds ratio [OR] = 0.17, 95% CI 0.07, 0.36, p<0.0001) and was not significantly different from the controls (OR = 1.81, 95% CI 0.79, 3.78, p=0.15). Duration of illness was associated with low BMD (OR = 1.16, 95% CI 1.08, 1.25, p<0.0001) and was negatively associated with the odds of AN recovery. Normal mean BMD values at each skeletal site were observed in women recovered ≥ 3 years. Conclusion: The results emphasize the importance of early and sustained AN recovery for the prevention and treatment of low bone mass in this population and may offer motivation for AN patients to make positive behavioural changes leading to successful, long-term recovery.

Keywords: bone mineral density
anorexia nervosa
osteoporosis
exercise
Advisor: Hawker, Gillian