VictorJuiz/thesis huggingface dataset:
Delayed Versus Immediate Corrective Feedback on Orally Produced Passive Errors in English

Research demonstrating the beneficial effects of corrective feedback (CF) for second language (L2) learning (e,g., Li, 2010) has almost invariably resulted from studies in which CF was provided immediately. Yet teachers are often encouraged to delay CF to avoid interrupting learners (Harmer, 2001). This study investigates how differences in the timing of CF on oral production affect L2 learning and learners’ reactions to CF. Theoretically, Immediate CF may facilitate L2 development by allowing learners to immediately compare their errors to accurate models (i.e., recasting, e.g., Doughty, 2001). The effectiveness of Immediate CF has also been linked to skill acquisition theory because some CF (i.e., prompting) is hypothesized to help learners proceduralize their L2 knowledge (Ranta & Lyster, 2007). This thesis introduces additional theoretical explanations to explain the effectiveness of both Immediate and Delayed CF. For example, reactivation and reconsolidation theory (Nader & Einarsson, 2010) holds that long-term mental representations are susceptible to change when they are recalled. Thus, both Immediate and Delayed CF may help learners alter their incorrect mental representations of language features if that CF reminds learners of those incorrect representations and provides them with accurate models. In a laboratory-based study, 90 intermediate-level adult ESL learners were randomly assigned to Immediate, Delayed, and No CF conditions. Learners took three pre-tests to measure their knowledge of the English passive construction: an aural grammaticality judgment test (AGJT), an oral production test (OPT), and a written error correction test (ECT). Next, they received some brief instruction on the passive. Learners then completed three communicative tasks in which the CF conditions were provided. These tasks were followed by immediate and delayed post-tests. Learners’ reactions to CF were elicited with a questionnaire. Mixed-design one-way ANOVAs revealed statistically significant improvement for all conditions over time on all measures, but no statistically significant differences between conditions. The questionnaires revealed that learners prefer Immediate CF, but that Immediate CF may constrain CF noticeability and learners’ independence, while Delayed CF may cause anxiety or embarrassment. In summary, altering the timing of CF did not differentially affect L2 development, but it did elicit different reactions from learners.

Keywords: timing of corrective feedback
corrective feedback
error correction
second language acquisition
learner preferences for corrective feedback
timing of instruction
form-focused instruction
second language learning
second language pedagogy
cognitive aspects of language learning
ESL
English as a second language
second language teaching
English passive voice
L2 learning
L2 teaching
types of corrective feedback
correction
reactivation and reconsolidation
cognitive comparison
skill acquisition
proceduralization
delayed corrective feedback
immediate corrective feedback
second language education
SLA
Advisor: Spada, Nina
Defining Immune Correlates of HIV Susceptibility in the Foreskin

HIV is a predominantly sexually transmitted infection that has infected over 60 million people and been responsible for 60 million deaths. To date, non-antiretroviral microbicides have failed to prevent HIV acquisition, or even increased it. This is likely because HIV preferentially infects activated immune cells (CD4+ T cells), taking advantage of the body’s attempts to defend itself. Therefore, relative immunoquiescence, as opposed to immune activation, may be protective. I hypothesized that men who are biologically more susceptible to HIV would have increased foreskin CD4 T cell activation, while the opposite would be true of men who are relatively resistant. The foreskin has recently been identified as a major site of HIV acquisition, but little previous research has been performed on this tissue. I therefore developed novel techniques to isolate viable, immunologically functional T cells from foreskin tissue. I then worked with the Rakai Health Sciences Program in Uganda to identify men undergoing elective circumcision who are HIV-Exposed but have remained SeroNegative (HESN, relatively resistant to HIV), and men with Herpes Simple Virus-2 infection (HSV-2+, relatively susceptible to HIV). I collected sub-preputial swabs and foreskin tissue from these men, and characterized numerous immune parameters in their samples. I found that HSV-2+ men had an increased relative abundance of CD4 T cells co-expressing the HIV receptor CCR5. In contrast, I found that HESN men had a decreased relative abundance of activated T cells (CD4/8 T cells producing TNFα) and Th17 cells (a pro-inflammatory T cell subset known to be particularly susceptible to HIV). Additionally, foreskin secretions from HESN men were more likely to have antibodies (IgA) able to neutralize HIV, and had more innate anti-viral peptides. I therefore propose HIV resistance may be driven by decreased T cell activation in genital tissue, in combination with increased secretion of anti-HIV immune proteins.

Keywords: HIV
T cells
Circumcision
Advisor: Kaul, Rupert
Small-signal Dynamic Stability Enhancement Of A DC-segmented AC Power System

This thesis proposes a control strategy for small-signal dynamic stability enhancement of a DC-segmented AC power system. This control strategy provides four control schemes based on HVDC supplementary control or modification of the operational condition of the HVDC control system to improve the system stability by (i) damping the oscillations within a segment using supplementary current control of a line-commutated HVDC link, based on the model predictive control (MPC) method (control scheme 1), (ii) minimizing the propagation of dynamics among the segments based on a coordinated linear quadratic Gaussian (LQG)-based supplementary control (control scheme 2), (iii) selectively distributing the oscillations among the segments based on a coordinated LQG-based supplementary control (control scheme 3) and (iv) changing the set-points of the HVDC control system in the direction determined based on the sensitivities of the Hopf stability margin to the HVDC links set-points (control scheme 4). Depending on the system characteristics, one or more of the proposed control schemes may be effective for mitigating the system oscillations. Study results show that (i) control scheme 1 leads to damped low-frequency oscillations and provides fast recovery times after faults, (ii) under control scheme 2, each segment in a DC-segmented system can experience major disturbances without causing adjacent segments to experience the disturbances with the same degree of severity, (iii) control scheme 3 enables the controlled propagation of the oscillations among segments and damps out the oscillatory dynamics in the faulted segment, and (iv) control scheme 4 improves the stability margin for Hopf bifurcations caused by various events. Since power system software tools exhibit limitations for advanced control design, this thesis also presents a methodology based on MATLAB/Simulink software to (i) systematically construct the nonlinear differential-algebraic model of an AC-DC system, and (ii) automatically extract a linearized state space model of the system for the design of the proposed control schemes. The nonlinear model also serves as a platform for the time-domain simulation of power system dynamics. The accuracy of the MATLAB/Simulink-based AC-DC power system model and time-domain simulation platform is validated by comparison against PSS/E.

Keywords: small-signal stability
HVDC
segmentation
Advisor: Iravani, Reza
Tate, Joseph
Systemic and Climate Diversity in Ontario’s University Sector

The extent and nature of institutional differentiation is a design choice among many that must be considered by policymakers not only when developing a higher education system but also when introducing policy changes to an existing system. Modifications to the design of Ontario’s higher education system have been suggested over the years in an effort to increase its quality (instruction and research) and accessibility in a cost effective manner. The fiscal climate of restraint has recently intensified the debate for structural changes through increased institutional differentiation in Ontario’s higher education system. Institutional diversity was examined using a mixed research method in two phases. This study first used hierarchical cluster analysis which suggested that there has been very little change in diversity between 1994 and 2010 as universities were clustered in three groups for both 1994 and 2010.However, by adapting Birnbaum’s (1983) diversity matrix methodology to Ontario’s university sector, there appears to have been a decrease in systemic diversity (differences in the type of institution and size of institution) and climate diversity (differences in campus environment and culture) between 1994 and 2010 and a projected further decrease to 2018. The second phase of this study used policy analysis and drew on mutually related theoretical perspectives from organizational theory as its primary conceptual framework to interpret and corroborate the decrease in diversity between 1994 and 2010. Interviews were also conducted with university presidents to gain a greater understanding of the key factors or barriers in Ontario’s reticence in proposing design changes in its higher education system. Having been informed by the policy analysis, interviews and projections of the extent of diversity to 2018, the study proposed a diversity policy for Ontario’s university sector. Diversity can be increased in Ontario’s university sector by providing institutions with competitive incremental funding allocations within each of three clusters that would specifically address government diversity objectives through a revised strategic mandate agreement process. Additional research funding should also be provided by the federal government to a limited number of research-intensive universities to ensure that Canadian institutions remain competitive on the world stage.

Keywords: Diversity
Ontario
Climate
Systemic
University
Advisor: Jones, Glen
Implications of Periodic Weak Thermal Stratification in the Epilimnion of Lake Opeongo

Episodic weak stratification is a persistent and important feature of the epilimnion of Lake Opeongo. Field studies were conducted in Lake Opeongo in 2009 and 2010 to assess the effect of the epilimnetic weak thermal stratification on turbulent mixing and ecological processes. Near surface thermoclines (as defined by dT/dz > 0.2 ̊C m-1 between 1 m and 2 m) occur approximately 20 % of the time and correspond to periods of high values of gradient Richardson number (Rig). Extended periods of near surface stratification (> 1 hr), account for more than 80% of the stratified period. We compare these findings with previous observations from the Experimental Lakes Area and discuss the biological implications of near surface thermoclines. The persistent weak temperature stratification that characterizes the entire epilimnion of Lake Opeongo, acts to reduce the magnitude of turbulent mixing. During these stratified periods, the values of Rig, increase, with a corresponding decrease in the rates of dissipation of turbulent kinetic energy, (ε ), the turbulence activity parameter, I = ε/νN2, and vertical eddy diffusivity (Kz). Mixing during cold fronts occur over time scales of minutes to hours, which work to erode diurnal thermoclines. The direct implications of weak stratification on aquatic organisms are also assessed. The presence of weak stratification also allows for the existence of internal waves within the epilimnion. A key observation in this thesis is the relationship between enhanced small-scale spatial variability in zooplankton distribution and the presence of internal waves in the weakly stratified epilimnion. To quantify this physical-biological coupling, we compare variance of isotherm displacement and gradient Richardson number (Rig) with small-scale spatial distributions of zooplankton. For smaller size ranges of zooplankton (284-450 μm), we find that spatial variability is statistically greatest for the highest values of variability of isotherm displacement. As vertical velocities estimated from wave characteristics are faster than swimming speeds of small zooplankton, these organisms become passively advected by the internal waves leading to increased spatial variability.

Keywords: environmental fluid dynamics
turbulence
stratification
Advisor: Wells, Mathew
Cultural Syndromes and the Appraisal of Common Cancer-related Stressors

Cultural values provide a system for evaluating situations we encounter; yet, they have seldom been tested in psychosocial oncology. The present research addressed this gap by testing the hypothesis that cancer-related events are stressful because they threaten highly regarded cultural values. As part of a larger study, 417 Western-born Caucasians and 121 Asian-born Chinese immigrants with head and neck cancer (HNC) completed the Individualism-Collectivism Scale (ICS), which measures their endorsement of four cultural syndromes (i.e., vertical-individualism, horizontal-individualism, vertical-collectivism, and horizontal-collectivism). However, the ICS did not tap these constructs identically across these samples. Consequently, I extracted a new common 3-factor measurement model: (a) Camaraderie with Co-workers; (b) Commitment to Family; and (c) Competitiveness. I cross-validated the new model in the HNC samples from which it was derived and in three independent chronic-disease samples. In all cases, results indicated weak invariance. To test the hypothesis, respondents reported the causes of stress (i.e., stressor appraisals) for 24 common HNC-related events. Stressor appraisals reported by a subset of respondents (196 Western-born Caucasians and 44 Chinese immigrants) were categorized based on whether they reflected threats to the cultural values tapped by the new scales. Because only stressor appraisals reflecting threats to commitment to family were identified, I tested the association between commitment to family and the numbers of stressor appraisals reflecting threats to that value. Hierarchical Poisson regression analysis indicated a significant Culture Group x Commitment to Family interaction effect (p = .045): the number of stressor appraisals reflecting threats to commitment to family increased with increasing sense of commitment to family in Chinese immigrants, but not in Western-born Caucasians. Hence, cultural values, in part, explain cross-cultural variation in the experience of cancer stresses. Attention to cultural values can facilitate culturally sensitive patient-centered care by identifying culturally specific causes of stress for targeted psychosocial interventions.

Keywords: psychosocial adjustment to cancer
cultural values
stress appraisal
psychometrics
Advisor: Devins, Gerald
Developing a Proteomic Prognostic Signature for Breast Cancer Patients

Breast cancer is a major health issue, affecting annually approximately 1.4 million women worldwide. It is a highly heterogeneous disease with the different subtypes having distinct clinical outcomes and different sensitivity to various treatment modalities. The focus of the present dissertation was the identification of novel proteomic prognostic markers for patients with early stage breast cancer. Three different approaches to identify potential prognostic markers were undertaken. First, we hypothesized that since different breast cancer subtypes have distinct clinical outcomes, breast cancer subtype-specific proteins may retain prognostic potential. Second, given the central role of estrogen signaling in breast epithelial cell biology, we hypothesized that estrogen-regulated proteins may be useful in predicting patient outcome. Finally, we hypothesized that genes related to survival based on meta-analyses of publicly available breast cancer tissue microarray data, may also demonstrate prognostic potential at the proteome level. As such, a variety of mass spectrometry-based approaches and biological samples were utilized for the discovery of these potential prognostic protein markers resulting in twenty-four candidates. Upon the identification of candidate biomarkers, a mass spectrometry-based assay for the simultaneous quantification of these proteins in breast cancer tissue samples was established. The developed assay was used for measuring the relative expression levels of the potential biomarkers in a cohort of 96 breast cancer tissue samples from untreated patients with early stage breast cancer. This exercise uncovered two proteins that showed the potential to discriminate between ER-positive patients at high and low risk of disease recurrence, namely KPNA2 and CDK1. In conclusion, the present dissertation describes the development of a preclinical exploratory study, from the discovery to the preliminary verification of potential prognostic biomarkers for breast cancer patients.

Keywords: breast cancer
mass spectrometry
Advisor: Diamandis, Eleftherios
Physiological Regulation of Short-term Food Intake in Children During Puberty

Three studies were designed to investigate the hypothesis that physiological and environmental variables are both independent and interactive in determining food intake (FI) in children and adolescents during puberty (8 – 18 y old). Study 1 investigated the effect of obesity, sex and pubertal status on appetite hormones in response to a mixed glucose and whey protein (WP) drink in adolescents. Obese adolescents had higher insulin, PYY and lower ghrelin than normal weight (NW) controls, with a more pronounced effect in males. Puberty did not affect insulin, but the change in PYY in response to the drink was greater and ghrelin was lower in mid-late pubertal than pre-early pubertal obese males. To further describe the role of puberty, Study 2 examined the effect of pubertal status on FI following consumption of glucose and WP drinks in male and female children. In mid-late pubertal children, mealtime compensation for energy from glucose was less at 60 than at 30 min, but not for whey. However, compensation for either drink was not different at 30 and 60 min meals in pre-early pubertal children. Finally to demonstrate the interaction between puberty and environmental influences on FI, Study 3 examined the effect of distraction (television viewing, TVV) while eating and pubertal status on food intake after a pre-meal glucose drink in girls. In Study 3, TVV had no effect on FI, however, glucose suppressed FI more with no TVV compared with TVV (24% vs. 10%). In postpubertal girls, glucose reduced FI by ~27% in both the no TVV and TVV conditions, but in peripubertal girls, reduction in FI was 22% without TVV and only 1% while TVV. Thus, the results of this research support the hypothesis that physiological and environmental variables are both independent and interactive in determining FI in children and adolescents during puberty.

Keywords: food intake regulation
puberty
Advisor: Anderson, G. Harvey
Microwave Assisted Extraction of Xylan

Xylan is one of the major hemicelluloses present in plant cell wall matrix, where it is closely associated with other cell wall components, cellulose and lignin. Xylan has enormous potential as a renewable biopolymer and recently, research in the direction of isolation and utilization of xylan is gaining lot of research attention. Extraction of xylan from the plant cell walls involves the hydrolysis of xylan and its transfer from the plant cell wall matrix to the hydrolyzing media. Current process of extraction involves prolonged heating of the biomass with the hydrolysis media at high temperature and/or pressure that leads to molecular degradation of xylan and limits its high potential polymeric applications. In this research, microwave assisted alkaline extraction of polymeric xylan from birch wood is investigated as an alternative to the time intensive conventional extraction. The hypothesis to be tested is that the microwave’s selective heating ability leads to the generation of hot spots through its interaction with the alkali present in the fibers and the resulting "explosion effect" loosen the recalcitrant fiber structure network thereby facilitating the hydrolysis of xylan and its dissolution before undergoing significant degradation. Effect of microwave extraction on the yield of xylan and wood solubilization, physico-chemical properties of wood fibers and of isolated xylan were investigated in comparison with conventional extraction. Low power input microwave (110 W) alkaline extraction was found to be an efficient alternative to the conventional extraction. FTIR and chemical composition of wood fibers after extraction demonstrated an increased removal of xylan from the wood fibre using microwave extraction. SEM, X-ray microtomography, and X-ray crystallinity studies of wood fibers demonstrated a porous and loosened fibre structure after microwave extraction confirming the hypothesis. Molecular weight of the isolated xylan using microwave extraction was found to be higher compared to the xylan isolated using conventional extraction indicating less molecular degradation. About 75% of xylan present in birch wood could be extracted using a low power input microwave heating under optimized extraction conditions of 8wt% NaOH solution, 1:8 (g:mL) solid to liquid ratio, and 25 minutes of extraction time.

Keywords: Xylan
Microwave extraction
Hemicellulose
Characterization
Biopolymer
Advisor: Sain, Mohini
Milk and its Components in the Regulation of Short-term Appetite, Food Intake and Glycemia in Young Adults

The hypothesis that milk consumption decreases short-term appetite and food intake and improves glycemic control compared with other caloric beverages in healthy young adults was explored in four experiments. The first two experiments compared isovolumetric amounts (500 ml) of milk (2% M.F.), chocolate milk (1% M.F.), a soy beverage, infant formula, orange juice and water on satiety and food intake and blood glucose before and after a meal provided at 30 min (Experiment 1) and 120 min (Experiment 2). Pre-meal ingestion of chocolate milk and infant formula (highest in calories) reduced food intake at 30 min, but not 2 h. Only milk reduced post-meal blood glucose in both experiments suggesting that its macronutrient composition is a factor in blood glucose control. Experiment 3 compared the effects of ad libitum consumption of milk (1% M.F.), regular cola, diet cola, orange juice and water at a pizza meal on fluid and ad libitum food intake and post-meal appetite and glycemia. Fluid volume consumed was similar, but all caloric beverages added to total meal-time energy intake. However, milk lowered post-meal blood glucose and appetite score. In Experiment 4, the effect of isovolumetric (500 ml) beverages of whole milk (3.25% M.F.) and each of its macronutrient components, protein (16 g), lactose (24 g), and fat (16 g) on glycemic control and gastrointestinal hormonal responses were examined. The reduction in post-prandial glycemia was mediated by interactions between its macronutrient components and associated with hormonal responses that slow stomach emptying and increase glucose disposal. Thus, the results of this research do not support the hypothesis that milk consumption decreases short-term appetite and food intake compared with other beverages; however, milk improves glycemic control by insulin-dependent and independent mechanisms.

Advisor: Anderson, G. Harvey