VictorJuiz/thesis huggingface dataset:
Evaluating the Potential of Scaling due to Calcium Compounds in Hydrometallurgical Processes
Keywords: Calcium sulphate
Gypsum
Anhydrite
Hemihydrate
Chemical Modelling
Solubility measurements
Transformation mechanism
Transformation kinetics
Hydrometallurgy
Scaling
Laterite Pressure Acid Leaching
Solid phase transformation

A fundamental theoretical and experimental study on calcium sulphate scale formation in hydrometallurgical solutions containing various minerals was conducted. A new database for the Mixed Solvent Electrolyte (MSE) model of the OLI Systems® software was developed through fitting of existing literature data such as mean activity, heat capacity and solubility data in simple binary and ternary systems. Moreover, a number of experiments were conducted to investigate the chemistry of calcium sulphate hydrates in laterite pressure acid leach (PAL) solutions, containing Al2(SO4)3, MgSO4, NiSO4, H2SO4, and NaCl at 25–250ºC. The database developed, utilized by the MSE model, was shown to accurately predict the solubilities of all calcium sulphate hydrates (and hence, predict scaling potential) in various multicomponent hydrometallurgical solutions including neutralized zinc sulphate leach solutions, nickel sulphate–chloride solutions of the Voisey’s Bay plant, and laterite PAL solutions over a wide temperature range (25–250°C). The stability regions of CaSO4 hydrates (gypsum, hemihydrate and anhydrite) depend on solution conditions, i.e., temperature, pH and concentration of ions present. The transformation between CaSO4 hydrates is one of the common causes of scale formation. A systematic study was carried out to investigate the effect of various parameters including temperature, acidity, seeding, and presence of sulphate/chloride salts on the transformation kinetics. Based on the results obtained, a mechanism for the gypsum–anhydrite transformation below 100°C was proposed. A number of solutions for mitigating calcium sulphate scaling problems throughout the processing circuits were recommended: (1) operating autoclaves under slightly more acidic conditions (~0.3–0.5 M acid); (2) mixing recycled process solutions with seawater; and (3) mixing the recycling stream with carbonate compounds to reject calcium as calcium carbonate. Furthermore, aging process solutions, saturated with gypsum, with anhydrite seeds at moderate temperatures (~80°C) would decrease the calcium content, provided that the solution is slightly acidic.
Integrating Drama and Historical Memory in Colombian Schooling: A Classroom Community of Memory and Drama
Keywords: Drama Education
Historical Memory

This is a research study that explores the kind of pedagogical possibilities that collective remembrance mediated by practices of drama in education, might offer to the work of memory. Under study is a drama-remembrance (an artistic and pedagogical project) that attempts to link significant historical learning with critical remembrance through the classroom drama praxis. Assuming the school as a terrain within which a community of memory is possible, this research is concerned with educational processes that facilitate the understanding of the ‘work of collective memory’. The hypothesis is that through the work of drama framed as a performative practice of remembrance, students can productively explore the work of memory; its functioning, implications and structures. In addition, by manipulating the elements of the art form, it is proposed that students also learn how drama works, its mechanisms and devices. I call this approach “Drama-Remembrance Praxis”, as it constitutes a particular application of theatre to the memory and remembrance framework. This dissertation provides an account of and analyzes key episodes of the research journey of a group of 16 students in a Grade 10 drama class, their drama teacher and myself -a drama artist, researcher and educator- as we collectively explored issues of historical memory through practices of process drama. The setting for this exploration was a project to initiate a drama classroom-based "community of memory" with one class in the Normal-Distrital Maria Montessori School, in Bogotá, Colombia, South America. Participant-researchers worked through questions regarding the public remembrance of the story of the Colombian Afro-descendant Manuel Saturio Valencia, one of last prisoners to be executed by the State before capital punishment was eliminated from Colombia in 1910. As an Afro-descendant, the story of Saturio's life and subsequent execution remains little known in Colombia. Thus at stake in this project was the recovery of forgotten stories, the construction of a more inclusive public memory, and the formation of a critical historical consciousness.
Antecedents and Consequences of Intragroup Conflict Among Nurses in Acute Care Settings
Keywords: Conflict
Nurses
Interactional justice
Core self-evaluations
Unit morale
Job stress
Job satisfaction
Conflict management style

One of the contributing factors to the current nursing shortage is job dissatisfaction due to conflict in the workplace. In order to develop strategies to reduce conflict, research is needed to understand the causes and outcomes of conflict in nursing work environments. This study tested a theoretical model linking antecedent variables (core self-evaluation, complexity of nursing care, unit size, interactional justice, managerial support, unit morale) to intragroup conflict, followed by conflict management, and ultimately, job stress and job satisfaction. A predictive, non-experimental design was used in a random sample of 277 acute care nurses in Ontario. Structural equation modeling techniques were used to analyze the hypothesized model. Final analysis revealed relatively good fit of data to the hypothesized model (Chi-square = 211.7, df = 80, CFI = .92, RMSEA=0.07). Lower core self-evaluation, higher complexity of nursing care, lower interactional justice, and poor unit morale resulted in higher intragroup relationship conflict, and ultimately a less ‘agreeable’ conflict management style, higher stress and job dissatisfaction. Conflict management style partially mediated the relationship between conflict and job satisfaction. Job stress also had a direct effect on job satisfaction and core self-evaluation had a direct effect on job stress. The study results suggest that conflict and its associated outcomes is a complex process, affected by dispositional, contextual and interpersonal factors. Nurses’ core self-evaluations, complexity of nursing care and relationships with managers and nursing colleagues influences the level of conflict they experience. How nurses manage conflict may not prevent the negative effects of conflict on job stress and job satisfaction, however learning to manage conflict using collaboration and accommodation may help nurses feel more satisfied with their jobs. In addition, education programs that contribute to an individual’s ability to feel more confident about their ability to manage conflict may help them cope more effectively with the stress generated by conflict.
Critical Determinants of the Risk-benefit Assessment of Antidepressants in Pregnancy: Pharmacokinetic, Safety and Economic Considerations
Keywords: antenatal depression
pharmacology
pregnancy
antidepressants

Untreated depression in pregnancy may result in adverse health outcomes to both the mother and her unborn child. Pharmacotherapy with antidepressants is the most common treatment option for depression; however, the decision to treat with medication becomes complicated by pregnancy. Risk benefit assessments are critical tools to guide the treatment decision. Factors that should be included in these analyses include the pharmacokinetics and pharmacodynamics of antidepressants in pregnancy and their maternal and fetal safety. The economic cost of untreated maternal depression is also important to keep in mind. When the pharmacokinetics of the antidepressants venlafaxine and bupropion were studied in pregnancy it was found that the apparent oral clearance rate of bupropion was increased in late pregnancy when compared to early pregnancy (p = 0.03). There was a trend for lower area under the curve for these medications when the third trimester was compared to the first trimester. When the metabolism of antidepressants was investigated using hair analysis it was found that there was increased metabolism in pregnancy when compared to the postpartum period for citalopram (p = 0.02) but not venlafaxine (p = 0.77). Follow up of depressive symptoms throughout pregnancy identified that depression scores were highest in the first trimester of pregnancy, which may be due to concurrent nausea and vomiting of pregnancy. A meta-analysis of paroxetine use in early pregnancy demonstrated that there was no increased risk for cardiac malformations; case-control studies had an odds ratio of 1.18 (CI95: 0.88 – 1.59) while a weighted average difference of 0.3% was found in case-control studies (CI95: -0.1 – 0.7%, p = 0.19) The direct medical costs incurred by the Ontario government due to discontinuation of antidepressant medications in pregnancy was estimated to exceed $20,000,000 CAD. The management of depression in pregnancy with pharmacotherapy is an important and complex issue. My study documents the advantages of conducting risk benefit assessments for vulnerable populations such as pregnant women with depression.
Regulation of Tie2 by Angiopoietin-1 and Angiopoietin-2 in Endothelial Cells
Keywords: Receptor trafficking

The tyrosine kinase receptor Tie-2 is expressed on the surface of endothelial cells and is necessary for angiogenesis and vascular stability. To date, the best characterized ligands for Tie-2 are Angiopoietin-1 (Ang-1) and Angiopoietin-2 (Ang-2). Ang-1 has been identified as the main activating ligand for Tie-2 while the role of Ang-2 has been controversial since its discovery; some studies reported Ang-2 as a Tie-2 antagonist while others described Ang-2 as a Tie-2 agonist. The purpose of this thesis was to understand: (1) how the receptor Tie-2 is regulated by Ang-1 and Ang-2 in endothelial cells, (2) to compare the effects of Ang-1 and Ang-2, and (3) to determine the arrangement and distribution of Tie-2 in endothelial cells. The research presented in this thesis indicates that Tie-2 is arranged in variably sized clusters on the endothelial cell surface. Clusters of Tie-2 were expressed on all surfaces of cells: on the apical plasma membrane, on the tips of microvilli, and on the basolateral plasma membrane. When endothelial cells were stimulated with Ang-1, Tie-2 was rapidly internalized and degraded. Upon Ang-1 stimulation, Tie-2 localized to clathrin-coated pits on all surfaces of endothelial cells indicating that one pathway mediating Tie-2 internalization is through clathrin-coated pits. After activation of Tie-2, Ang-1 dissociates from the endothelial cell surface and accumulates in the surrounding medium. When experiments were repeated with Ang-2, it was discovered that Ang-2 induced all of the same effects on Tie-2 as Ang-1 but at a much reduced level and rate, indicating that Ang-2 likely functions as a partial agonist for Tie-2 in endothelial cells.
Adolescent Male Dancers' Embodied Realities
Keywords: male dancers
male dance students
gender
identity
documentary on males
adolescent
masculinity
dance and physical education
homosexual
gay
dance curriculum
dance pedegogy

This dissertation looks at adolescent male dance students who challenge the dominant perceptions of masculinity by participating in dance, an art form which has been subjected to feminine and homosexual stereotypes. With a multi-methodological approach—qualitative, arts-informed, autobiography, interviews, videotape, and performance—this research investigates and explores the largely unknown realities regarding adolescent male dance students; why they decide to take dance; what makes them continue or stop dancing; how their perceptions of dance are transformed over time; how they feel when they are dancing; the realities they embody in studio and on stage; their message to the public about who they were, who they are, and what they want to be in and through dance. The researcher challenges the socially constructed epistemology that dance is merely an entertainment while exploring the relationship between mind and body; gender, race, and identity; literature and literacy; physical education and dance; the professional and the novice; the hows and the whys; female and male dance educators; dance pedagogy (theory) and curriculum delivering (practice); and the association of homosexuality and heterosexuality in the context of dance and its effect on adolescent male students’ willingness to dance. This study shows that families, friends, teachers, school administrators, dance class environment, media (So You Think You Can Dance), and technology (internet) have all created various levels of impact on adolescent males’ decision to participate in dance at a high school. Data and implication from this research can serve as a catalyst for future studies on adolescent male dance students. Findings can also be applied to dance programs at all levels, curriculum development, and teacher education. This electronic dissertation encompasses graphs, photos, audio and video clips, webpage links, and even a full-length documentary movie to enhance the research finding and maximize the power of a multimodal design (Jewitt & Kress, 2003).
Nuclear Sharing and Nuclear Crises: A Study in Anglo-American Relations, 1957-1963
Keywords: Nuclear Nonproliferation

Between 1957 and 1963, both Anglo-American discussions of nuclear cooperation and the wider debate on nuclear strategy within NATO were often dominated by the question of whether Britain’s deterrent would be amalgamated or integrated into a wider NATO or European force, such as the proposed MLF (Multilateral Force). This dissertation discusses the development and impact of competing British and American proposals for “nuclear sharing” within the context of European economic and political integration as well as that of discussions within NATO of the appropriate strategy for the alliance in an age of mutual nuclear vulnerability between the superpowers. Particular attention is paid to the context of successive nuclear crises in world politics during this period, from Sputnik to the Soviet ultimatum over Berlin through the Cuban missile crisis. The divergent opinions among the leaders of the major powers over the appropriate responses to these crises shaped the debate over nuclear sharing and form a previously neglected dimension of this topic.
The Synaptic Role of Neuronal Calcium Sensor 1 in Dentate Gyrus Plasticity, Curiosity and Spatial Memory
Keywords: Curiosity
Memory
Mouse
Dentate Gyrus
LTP
NCS-1
D2 recrptor
L-741,626
Plasticity
Hippocampus
Learning
Exploration
Schizophrenia
Bipolar
Endophenotype
Gallein
Water Maze

Only 200 years ago, virtually nothing was known about the biological workings of the mind. Today, there is a deep (though far from complete) understanding of the cellular and molecular mechanisms underlying the encoding of memory, arguably the most fundamental aspect of a cognitive being. In this thesis, I describe experiments that help complete this understanding and identify the very first molecules underlying curiosity. By using an inducible rtTA2-M2 double transgenic system to selectively overexpress the calcium sensor Ncs1 in the adult murine dentate gyrus, I created an animal with facilitated long-term potentiation, enhanced rapid acquisition of spatial memory and greater curiosity. These phenotypes are reversed by direct infusion of a small membrane-permeant interfering peptide designed to block complex formation between NCS-1 and Dopamine type-2 receptors (D2 receptors). Pharmacological antagonism of D2 receptors also attenuates plasticity in wild-type mice and direct antagonism of D2 receptors in the dentate of cannulized wild-type mice prevents spatial memory formation. Conversely, application of a dominant negative NCS-1 peptide reduces synaptic transmission in the dentate gyrus and impairs spatial fear learning. Far less understood than the mechanisms governing learning and memory, are the mechanisms used by the brain to generate curiosity. Strikingly, Ncs1 overexpressing mice also demonstrate increased exploratory behaviours in a variety of novel, non-fearful environments. But they do not explore novel fearful environments any more than their littermate controls. I argue that the specificity of this phenotype represents an effect on curiosity, thereby identifying NCS-1 and D2 receptors as the first known regulators of this primordial mental state. I propose that the generation of curiosity is a fundamental feature of the nervous system and is upstream of learning and cognition. As such, molecular cascades involved in curiosity likely also play roles in mental illnesses. To investigate this theory, I generated an NCS-1 point mutant mouse line. NCS-1P144S/P144S mice show endophenotypes of schizophrenia and depression, supporting the link between curiosity and mental illness. I integrate my findings with the current literature and propose a means to investigate the role of NCS-1 in humans with mental illnesses.
Transcriptional Regulation of the Mouse Adrenal Cyclase Type 4 (Adcy4) in Y1 Adrenocortical Tumor Cells
Keywords: Adenylyl cyclase
Steroidogenesis
Steroidogenic factor 1 (SF1)
Gene regulation

Adenylyl cyclase (Adcy) is an important early effector of adrenocorticotrophin (ACTH) on the adrenal cortex; however, this enzyme consists of ten isozymes in mammalian cells and the factors governing the expression of different Adcy isozymes have not been well defined. The aim of this study is to investigate the regulation of mouse Adcy4, one of ten isozymes, in Y1 adrenocortical tumor cells and in mutant subclones derived from the Y1 cells. Adcy4 is expressed at a high level in brain but at lower levels in many other tissues including the Y1 cells. Moreover, this isozyme is specifically deficient in Y1 mutants with impaired steroidogenic factor 1 (SF1) activity. These observations support a hypothesis that Adcy4 expression is influenced by both ubiquitously expressed and tissue-specific transcription factors. My sequencing results indicate that mouse Adcy4 is highly homologous to the human and rat counterparts; its gene is located less than 1 kb downstream of Ripk3 and contains 26 exons. Primer extension and in silico analyses suggest that Adcy4 contains a TATA-less promoter and initiates transcription from multiple sites. Luciferase reporter gene assays indicate that Adcy4 promoter activity is mainly stimulated by the proximal GC-rich region but is inhibited by the first intron. This 124 bp GC-rich region is well conserved among several mammalian species and exhibits strong promoter activity in Y1 cells, which is functionally compromised in the Adcy4-deficient mutant. Within this region, three Sp1/Sp3- and one SF1-binding sites have been identified which bind the corresponding proteins Sp1 and Sp3 or SF1 in electrophoretic mobility shift assays (EMSAs). Site-directed mutagenesis reveals that the 5’-most Sp1/Sp3 site enhances Adcy4 promoter activity, whereas the middle Sp1/Sp3 and SF1 sites each repress this activity. In Y1 mutant cells, mutating the SF1 site restores Adcy4 promoter activity and knocking down SF1 with shRNA increases Adcy4 expression. All these data demonstrate that Adcy4 expression is under the control of the ubiquitous factors Sp1 and Sp3 and the tissue-specific factor SF1 and establish that SF1 is a repressor for Adcy4 promoter activity. This study is the first to demonstrate a repressor function for SF1 in certain promoter contexts.
Probing Star Formation with High Resolution Spectroscopy: Multiplicity, Disk Braking, and Accretion in Chamaeleon I and Taurus-Auriga
Keywords: Star Formation
Spectroscopy

In this thesis, we focus on obtaining and interpreting observational information on (i) the role of multiplicity on the properties of young stars; (ii) the early evolutionary influence of circumstellar disks; and (iii) the nature of accretion in young systems. To facilitate this research, we conducted an extensive multi-epoch high-resolution spectroscopic survey at optical wavelengths (3,200-10,000 A) of ~200 T Tauri stars in the ~2 Myr old Chamaeleon I, and Taurus-Auriga star-forming regions with the Magellan Inamori Kyocera Echelle (MIKE) spectrograph on the Magellan Clay 6.5 m telescope. From the spectroscopic data, we identify eight close binaries and four close triples, of which three and two, respectively, are new discoveries. We find that the multiplicity fraction for Cha I and Tau-Aur are similar to each other, and to the results of field star surveys. The frequency of systems with close companions in our sample is not seen to depend on primary mass or accretion. We probed for evidence of disk braking. We did not see a statistically significant difference between the distribution of rotational velocities with the presence of an inner disk. Also, our findings show that F-K stars in our sample have larger rotational velocities and specific angular momentum than M stars. We also analyzed accretion variability in our sample using the H\alpha 10% width and the CaII-8662 line flux as accretion diagnostics. We find that the maximum extent of accretion variability in our sample was reached on timescale of a few days, indicating that rotation could significantly contribute to the variability.
Evaluating Clinical and Immunologic Correlates of HIV Shedding at Mucosal Sites
Keywords: HIV RNA
Mucosal Immunology
Gut Immunology
HIV Transmission
CMV Reactivation
HAART and Transmission

HIV infects over 33 million people worldwide with a new infection occurring every 9 seconds. Sex is the primary mode of transmission and the majority of new infections occur during unprotected sexual contact between an HIV-infected individual and an uninfected sexual partner(s) since HIV infected individuals tend to shed virus in their genital secretions. The infectiousness of an individual is closely tied to the amount of virus in blood, which is closely associated with HIV levels shed in semen or vaginal fluid or rectal secretions. Although, Highly Active Antiretroviral Therapy (HAART) is associated with complete suppression of HIV RNA in blood to undetectable levels, the impact of HAART on semen HIV RNA levels is less clear. I evaluated the correlation between systemic and mucosal HIV-specific CD8+ T cell immune responses and HIV RNA levels in blood and semen. Overall, there was a strong positive correlation between HIV RNA levels in blood and semen. Neither systemic nor mucosal (in semen) HIV-specific CD8+ responses were associated with HIV RNA levels in blood or semen, in fact CD8+ T cell immune responses in semen correlated with increased HIV RNA levels in semen. Furthermore, inflammatory cytokines (IL-6, and IL-8) CMV levels in semen were associated with increased semen HIV RNA shedding. HAART initiation was associated with complete suppression of HIV viremia, but a significant proportion of individuals on suppressive HAART continue to shed HIV RNA in semen even after 6 months, and this isolated virus was infectious and often present at high levels (> 5000 copies/mL). Nevertheless, long-term HAART was associated with complete immune reconstitution of CD4+ T cells in the sigmoid colon of HIV-infected individuals on long-term therapy. These findings demonstrate that neither systemic nor mucosal HIV-specific CD8+ responses, when assayed with IFN- production as an endpoint, were associated with reduced HIV RNA levels in blood or semen. Semen HIV RNA levels did correlate with local inflammatory cytokines and CMV reactivation. Furthermore, despite effective HAART a significant proportion of HIV-infected men continued to shed HIV RNA in semen. However, long-term completely suppressive HAART was associated with complete immune reconstitution of the sigmoid colon.