VictorJuiz/thesis huggingface dataset:
Optical spectroscopy of intact and intermixed gallium arsenide/aluminum arsenide superlattice structures

Raman and PL optical spectroscopy are developed to characterize QWI in GaAs/AlAs SL devices, including bandgap gratings for quasi-phase matching (QPM). The phonon dispersion in ideal GaAs/AlAs SL is calculated and the effects of intermixing are examined. Optimization of the Raman measurement is discussed and as-grown, large-area intermixed, and bandgap grating samples produced from 14:14 GaAs/AlAs SL are characterized. PL measurement confirmed the predicted bandgap from bandstructure calculation and revealed the presence of complete or incomplete intermixing. Raman measurement profiles indicated the SL width, the modulation along the intermixed grating, and the degree of intermixing in large-area samples. In edge-measurement, the GaAs IF modes offer the best SNR between intact and intermixed material followed by the GaAs-like TO peak position and the peak intensities of the TO modes.
Enhanced dissolution of a tetrachloroethylene DNAPL in a two dimensional model aquifer

The objectives of this project are to determine the potential for anaerobic microbial cultures to biodegrade chlorinated ethenes present as dense, non-aqueous phase liquid (DNAPL) and to determine the potential for biodegradation to enhance mass transfer rates from the DNAPL into the aqueous phase. The effect of enhanced bioremediation on DNAPL was evaluated using two-dimensional model aquifers containing a tetrachloroethene (PCE) DNAPL. This study involved the construction and operation of a two dimensional model aquifer using a PCE DNAPL. Duplicate model aquifers were constructed, one serving as a control for the other. The model aquifers were packed with soil collected from Dover Air Force Base, DE. The study consisted of four phases: setup, groundwater flush, biostimulation and bioaugmentation with KB-1, an enriched dechlorinating culture. During biostimulation, no observable increase in mass flux was observed, but bioaugmentation doubled the rate of dissolution compared to the control model aquifer.
The role of Notch signaling during T cell commitment and differentiation

The nature of the molecular interactions provided by the thymus that predicate T cell development remains obscure. In this thesis, I demonstrate that the bone marrow (BM) stromal cell line OP9, when made to express the Notch ligand Delta-like-1 (Dll1), loses its ability to support B cell lymphopoiesis, and acquires the capacity to induce the development of CD4 CD8 double- and single-positive T cells from various hematopoietic progenitor cells. Both gammadelta-TCR + and alphabeta-TCR+ T cells are generated, and CD4- CD8+ TCRhi cells produce gamma-interferon following CD3/TCR stimulation. Dll1 expressed on OP9 cells provides the necessary signals to induce T cell commitment, stage-specific progenitor expansion, TCR gene rearrangement, and T cell differentiation in-vitro. A normal program of T cell differentiation was also observed from embryonic stem cells (ESCs) cultured on these OP9 cells, which expressed multiple T lineage-associated genes in response to Notch receptor-Dll1 interactions. Furthermore, ESC-derived T cell progenitors effectively reconstituted the T cell compartment of immunodeficient mice, and were capable of generating an antigen specific response to a viral challenge. Using this culture system, I demonstrate that a substantial proportion of early thymocytes retain NK cell lineage potential, and that Notch signals act prior to T cell lineage commitment to maintain T cell lineage specification in early thymocytes. Furthermore, Notch receptor-ligand interactions are shown to be critical throughout T cell development. Thus, it is likely that the expression of Delta-like ligands in the thymus underpins its unique ability to promote T cell lineage commitment and differentiation.
Emotional states differentially bias extrastriate correlates of the attentional spotlight

Extant behavioral research suggests that positive and negative emotional states differentially influence visuospatial attention by broadening or narrowing, respectively, the scope of attended information in one's visual field. The present fMRI study hypothesized that emotion differentially modulates selective attention via a common neurophysiological mechanism embedded in early phases of visual processing, namely, the attentional spotlight. This was accomplished with a block design experiment consisting of affect induction blocks (positive, neutral, negative) alternating with 'flanker' blocks. The flanker task employed rapid presentations (300ms) of composite face/place (center/surround) stimuli to distinguish category-selective regions within extrastriate cortex. The central face was attended (gender decision task), rendering the peripheral place unattended. Fourteen individuals (age=22.03+/-0.68; education=15.57+/-0.68) participated. Valence-dependent encoding patterns were examined at the group level using factorial statistical parametric models. Consistent with predictions, positive affect increased encoding of the unattended flanker information (i.e. broadened attention) and negative affect decreased flanker encoding (i.e. narrowed attention).
The use of data envelopment analysis in the measurement of software development team performance: A quality focused approach

The linear-programming tool Data Envelopment Analysis (DEA) is applied to the measurement of software development efficiency. New DEA models are constructed and applied to project data provided by a large Canadian Financial Institution (FI). One of the main contributions to the literature is the use of quality metrics, namely client satisfaction survey scores measuring software team performance. And uniquely, size metrics were left out of the analysis. For much of its existence the software industry has been plagued by shortcomings in its ability to consistently develop effective products in an efficient manner. This has resulted in budget and schedule overruns, unmet user needs, unusable applications, and ultimately a loss of business. The technical and scale efficiencies of the software projects are analyzed using two separate DEA models. Characteristics of efficient projects are analyzed, and relationships among quality, efficiency, and other projects factors are investigated.
The relationship between the gifted adolescent boy and school

Current discussions in the popular press indicative of a public perception that boys are not doing well in school are borne out by recent test scores in some jurisdictions, especially in the areas of literacy. Boys who are identified as gifted are singled out as talented in an area where boys may prefer not to be seen as excelling, especially in early adolescence. This is a narrative inquiry about what the relationship of adolescent boys in a gifted congregated program is to school. It is told by female teacher of gifted intermediate students observing boys in another congregated class for gifted students. The author comes to consider the impact of stereotypes on relationship of these boys with school and her own biases as a teacher of boys.
ESL infusion in pre-service teacher education: a vehicle for exploring the beliefs and practices of teacher educators

Key findings suggest that, despite the constructivist and critical approaches to teacher education reflected in much of the data, institutional and structural constraints accompanying a nine-month B. Ed. program delivered to 1300 candidates limit the success of adequately addressing diversity and equity-related initiatives such as ESL Infusion. Additional support should be provided for teacher educators in promoting inclusive practices through revised policies and models of program delivery, recruitment of both teacher candidates and instructors who demonstrate anti-discriminatory stances and practices, and formal education for teacher educators. This thesis analyzes the extent to which three different teacher educators at the Ontario Institute for Studies in Education of the University of Toronto (OISE/UT), operating within the constraints of their professional circumstances and the scope of their beliefs, promote ESL-inclusive teaching strategies and issues in their pre-service courses as part of an institution-wide ESL Infusion Initiative. Examining ESL infusion in teacher preparation is particularly relevant at a time when increasing cultural and linguistic diversity in Ontario schools coincides with reduction in resources and specialist support for ESL learners. Using critical ethnographic research methods, I use the lens of ESL infusion to consider the beliefs and practices of teacher educators as they relate to ESL-inclusive pedagogy and concepts of effective teacher preparation more broadly.

Keywords: English language, Study and teaching
Linguistic minorities, Education
Linguistic minorities, Ontario
Inclusive education, Study and teaching
Inclusive education, Ontario
Teachers, Training of
Teachers, Ontario
A journey through science: Reading "Wilhelm Meisters Wanderjahre" (1829) in light of Goethe's scientific theory (Johann Wolfgang von Goethe, Germany)

The dissertation seeks to investigate the significance Goethe's scientific endeavours had on his literary production. Although perceived by many as conflicting areas of interest, throughout his life the author engaged with both science and literature, dedicating himself to each field with equal curiosity. The importance of his scientific work has, however, been generally overlooked by critics who focus on him primarily as a literary figure and who tend to discount his scientific manuscripts. This study attempts to rectify this scholarly oversight by illustrating the constant presence of science in the author's life and by demonstrating the importance it had on his literary work. Chronicling the development of his scientific worldview helps supports the contention that investigations into the natural world were a constant part of his intellectual life. A detailed analysis of the Colour Theory (1810), his most sophisticated study, epitomizes the complexity of his mature scientific thought. As he grew older, he increasingly drew upon his scientific modus operandi in the writing of his late literary work, integrating scientific concepts into fictional texts. The text that I use to elucidate the interplay between his scientific and literary modes of thinking is Wilhelm Meisters Wanderjahre (1829), Goethe's last lengthy prose work. The Wanderjahre conspicuously lacks a traditional literary structure and therefore cannot be easily interpreted in literary terms. It is also, of course, not a scientific treatise, but if one keeps Goethe's scientific work in mind one can readily read the text as, if not entirely conventional, certainly coherent.
Biological applications of the atomic force microscopeb: measuring the forces that hold DNA together, and, Molecular level, direct, real time observation of the interactions of RecA protein with double stranded DNA

Employing the Atomic Force Microscope (AFM), two biological systems are examined under biological conditions. The force holding together single base pairs of DNA is probed. Measuring the force required to rupture a perfect double helix, a double helix with a single mismatch, and a double helix with a double mismatch, arranged in a microarray, the need for precise determination of the AFM tip spring constant is precluded. The large volume of data collected required the implementation of cluster analysis, used for the first time in single molecule force spectroscopy. The rupture force of the double helix ranged from 10 to 80 pN depending on the length of the double helix. Importantly, we found that the force contribution from both AT and GC base pairs is the same. RecA protein's interaction with double stranded DNA is studied using time resolved AFM. The RecA/DNA nucleofilament is formed under physiological conditions and imaged. Several different species are formed, and have a pitch of 10 nm. The assembly of the RecA/DNA complex is monitored by examining contour length change over time. The assembly pathway occurred via a slow nucleation step, followed by a rapid growth phase. The lag time was 25 minutes, and the growth time was 17 minutes. The maximum growth speed was 92 RecA per minute. The disassembly of the complex is monitored in real time under buffer at pH 7.4 and 5.6, at a time resolution on the order of 2 minutes, and a spatial resolution better then 50 nm. The complexes disassemble from multiple discrete nodes in a non-random manner. At pH 7.4 the disassembly is rapid (up to 39 monomers per minute per node), and two to four times slower (as slow as 4.5 monomers per minute per node) at pH 5.6. The design and implementation of a hot stage is described. The hot stage employs a simple, cost-effective design that allows a user to easily heat an AFM sample to 37 Celsius for experiments on biological systems. This is demonstrated by imaging DNA at ambient and physiological temperature.
Conducting interdisciplinary analysis of youth literature: a study of the witch in recent young adult novels

This dissertation considers how an interdisciplinary analysis of the witch figure in contemporary young adult literature can facilitate the construction of analytical frameworks that bridge the division between the literary and practical approaches to youth literature, exploring the nature of this body of work as the aesthetic embodiment of adult beliefs and values about youth development and education. In response to the recent calls from scholars of children's literature for increased interdisciplinarity in a field that has traditionally been divided among "book people" and "child people," this study is an example of how literary critical approaches to novels written for young people can be complemented by the concepts and models borrowed from practical or non-literary fields. As the witch is a figure that has been characterized by its resistance to easy definition or categorization, the dissertation shows how the witch's significant and complex presence in adolescent culture can be organized into various motifs whose literary manifestations reflect larger cultural ideas about adolescence. Taking the popular "wicked witch" motif as a starting point, the study shows how the narrative changes that the archetypal wicked witch figure undergoes in her movement from fairy tales to the young adult novel reflect adult beliefs about the adolescent understanding of evil as something that must be 'known' rather than conquered. It explores how, in spite of their magical elements, novels about teen "blood witches" reveal the dominance of the theme of identity development in the social and psychological construction of adolescence. The dissertation analyzes the treatment of "historical witches" in novels about the witch trials in order to show how historical fiction is itself a pedagogical literary form that carries with it political and educational implications for teaching history to young readers. Finally, it examines the contradictory relationship between instruction and delight in novels about "real witches" or Wiccans, where the popularity of witchcraft in youth culture has a paradoxical impact on the pedagogical goals of authors who attempt to educate readers about their religion while trying to meet commercial demands for sensationalized depictions of witchcraft.
Human umbilical cord Wharton's jelly as a source of mesenchymal progenitors capable of expressing a functional osteogenic phenotype in vitro

One of the most important challenges in the development of cell-based therapies, including those of the emerging field of tissue engineering, is to find a source of useful cells. Solutions are not readily available when addressing the need to reconstitute the connective tissues of the body. Yet it is these tissues, bone, cartilage etc., which are increasingly needed as connective tissue degenerative diseases become a more significant problem with the increasing aged population. Thus, there is an acute need to find a practical and simple source of connective tissue cells for such applications. The work represented here has clearly demonstrated a unique population of cells which can be easily isolated from Wharton's jelly, the tissue surrounding the vessels of the human umbilical cord. Among these cells, which are not from the blood, but from the connective tissue of the cord, are a sub-population which is able to rapidly form human bone matrix in cell culture. The cell isolation procedure is novel, the harvested cells proliferate and differentiate rapidly compared to existing sources of connective tissue progenitors and, the results show that the cells presenting neither class of major histocompatibility complex (MHC) antigens can be enriched for by cryopreservation. Thus, this unique cell population may represent a significant alternative source of cells for allogeneic cell-based therapies and tissue engineering.
Detection of RNA in highly purified human cytomegalovirus virions

Human cytomegalovirus (HCMV) is an important pathogen in immunocompromised populations. Although classically considered a DNA virus, a study reported the detection of viral transcripts within purified HCMV AD169 virions. It is not known whether the RNAs are present in all HCMV strains. The objective of this study was to determine if the transcripts are found in HCMV strains Towne, Davis and a low passage clinical isolate, CL203. HCMV-infected cell supernatant was concentrated through 20%-sorbitol, and extraneous nucleic acids were digested. Centrifugation through a glycerol-potassium tartrate gradient separated the virions and dense bodies. Electron microscopy confirmed the identity of the particles, and immunofluoresence assays confirmed their infectivity. RNA was extracted from the particles for RT-PCR. The UL21.5 and IRL/TRL 2-5 transcripts were detected in purified virions of the four HCMV strains. Presence of these transcripts in CL203 demonstrates that the packaged transcripts are not unique to lab-adapted strains.
Essays in development economics: evaluating solutions to asymmetric information in credit markets

This thesis examines the impacts of interventions in credit markets characterised by severe problems of asymmetric information. The first essay, “Group lending and borrower default: empirical evidence,” examines the relative effectiveness of competing lending methodologies. Group lending theory claims to mitigate problems of asymmetric information that lead to adverse selection, moral hazard, state verification and contract enforcement. This chapter, using data from a Toronto-based microcredit program, presents empirical evidence that group lending, while leading to assortative matching, does not lower default rates when compared to conventional individual lending. The second essay, “Never do business with your friends: group lending, joint liability and dynamic incentives,” develops two simple theoretical models to explore the dynamic nature of joint liability contracts. From these models, I derive testable implications and then evaluate the predictions utilizing a unique panel data set. I find that dynamic incentives are an important feature of group lending programs.
Characterization of dopamine receptor function using different transgenic and knockout animal models

Dopamine receptors represent important physiological targets for the neurotransmitter dopamine as well as a number of drugs used to treat dopamine-related disorders. We utilized molecular genetic approaches in the nematode C. elegans and mice to gain an understanding of dopamine receptor function in vivo. In C. elegans we identified a gene (dar-1) encoding two alternatively spliced forms of a dopamine receptor. Using functional pharmacology we showed that dopamine is 10-fold more potent in activating either DAR-1 isoform compared to (nor)epinephrine, while other biogenic amines were ineffective at these receptors. HPLC analysis of nematode extracts revealed the presence of dopamine, including its precursors and metabolites, but not (nor)epinephrine, suggesting that dopamine is most likely the endogenous ligand for DAR-1 receptors.
School and parental correlates of adolescent substance use

This quantitative study assessed the association of various school factors with adolescent substance use, and whether the quality of the adolescent---parental relationship moderated this association. Using the Center for Addiction and Mental Health's (CAMH) 2003 Ontario School Drug Use Survey, data was analyzed from 3,152 adolescent students between the ages of 12 and 20. Logistic regression analysis showed that a number of academic factors are positively (school safety, school belonging) and negatively (academic orientation, views on classes and teachers) associated with adolescents' use of alcohol, cannabis, hard drugs, and a cannabis use problem indicator. Further, the perceived quality of the adolescent/parental relationship appears to moderate the association between certain school factors and cannabis use, hard drug use, and problem level cannabis use. Results are discussed in terms of their integration with existing substance use literature, their implications for adolescent development and substance use prevention programs.

Keywords: Teenagers, Drug use
Parent and teenager
High school students, Drug use
High school students, Attitudes
Academic achievement
Teacher-student relationships
Effects of a college instructor's first engagement with reform-based mathematics on her subject conceptions and conceptions of mathematics education

A case study of a college instructor's first engagement with reform-based approaches to teaching mathematics was the focus of this study. The researcher and study's participant co-taught a fractions unit in a community college setting using a reform-based approach. The researcher introduced the participant to reform-based methods of teaching mathematics, and served as a mentor as this manner of teaching was implemented in the participant's classroom. The participant's conceptions of mathematics were examined prior to, and upon completion of the study. Though no major changes occurred in the participant's conceptions of mathematics, minor changes were demonstrated, such as the participant's realizations of concrete and conceptual mathematical understandings. Further, differences in the researcher and participant's conceptions of mathematics accounted for differences in how each perceived the taught unit. The researcher, who has fallibilist conceptions of mathematics, perceived the unit to be more successful than the participant who exhibited more absolutist conceptions.
Diode LASER-MTA pulpotomy for the treatment of pulpally involved human primary teeth

Purpose. Investigate whether a diode LASER pulpotomy with MTA sealing is an acceptable alternative to the formocresol-ZOE pulpotomy in human primary teeth. Methods. Randomized, single blind study was used with a sample of 16 children aged 3 to 8 years. Twenty-six pairs of teeth were selected based on clinical and radiographic criteria. One tooth from each pair was randomly assigned to either the LASER-MTA group or the formocresol-ZOE group. Teeth were followed up at 2.3, 5.2, 9.5 and 15.7 months. Primary investigator and a blinded clinician assessed radiographs. Failures were extracted and photographed. Conclusions. LASER-MTA pulpotomy displayed reduced radiographic success compared to formocresol-ZOE pulpotomy. These results were not statistically significant. Results. All teeth were clinically sound at each follow-up. Seven LASER-MTA treated teeth were radiographic failures compared to 3 formocresol-ZOE treated teeth. Results were not significant (p> 0.05). Photographic analysis revealed technique errors and signs of a disease process.