VictorJuiz/thesis huggingface dataset:
Voltage source inverter for voltage and frequency control of a stand-alone self-excited induction generator

This thesis investigates the application of a Voltage Source Inverter based controller for the regulation of voltage and frequency of a stand-alone self-excited induction generator. The steady state and dynamic system equations are formulated and the system behavior is studied. Based on the model, the design of the VSI-based controller is obtained. The design and rating of the controller with different DC side configurations is derived for the system model. An experimental generator system with the proposed controller has been built. In order to verify theoretical results and the technical feasibility of the VSI-based controller, various tests are conducted. The test results demonstrate the excellent performance of the proposed concept.
The human veto phenomenon, an in vitro investigation of antigen-specific T lymphocyte suppression

Veto cells deliver signals that suppress cellular immune responses directed against the antigen-MHC displayed by the veto cell. This is the first investigation of the human veto phenomenon. Activated human T cell lines were found to inhibit cellular immune responses directed against their HLA antigens, resulting in the functional deletion of cytotoxicity only towards targets syngeneic with the veto cell. Controls demonstrated that the inhibition was not due to nutrient starvation, cold target competition nor non-specific elimination of responders by the veto population. Exogenous IL-2 did not reverse veto. Time course experiments showed that human veto cells were suppressive when added within the first 50 hours of MLR. In contrast to mouse veto where only CD8$\sp+$ T cells can inhibit, both CD4 and CD8 activated human T lymphocytes can veto, posing a new hypothesis for the veto mechanism. These findings are promising for the clinical application of veto in graft-vs.-host disease prophylaxis.
Women's nonprofit-organizations, funding, nature, management, dilemmas

This thesis reflects an interest in both social services and the feminist movement in Canada. The more specific subject matter is women's nonprofit organizations in Toronto, with a special emphasis on the financial element. Revenue data from twenty-four nonprofit organizations and two (provincial) government agencies have been gathered from financial statements, and grouped into two categories. The income of each organization has been divided into direct government funding, and other sources of revenue. Subsequent chapters deal with the nature of the "third sector" as a unique economic enterprise, lying between the government and private sectors; management problems in nonprofit organizations; the financial problems particular to nonprofit organizations; and the role of women in the social services. A constant attempt has been made to stress Canadian realities. The thesis maintains a critical standpoint on the feminist movement in context of time and place.
Measurement and partitioning of persistent organic pollutants in the environment, application of octanol-air partition coefficients

This thesis considers the measurement and partitioning of several classes of persistent organic pollutants (POPs--namely, polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs), and polycyclic aromatic hydrocarbons (PAHs). Octanol-air partition coeffcients (KoA) were measured for 18 PCBs, 24 PCNs, and 4 PAHs over a range of environmentally relevant temperatures. The results show that in all cases the value of KoA varied log-linearly with the inverse absolute temperature and that in general, the enthalpy associated with the transition from octanol to air, [Delta]HOA, was similar to the enthalpy of vaporization, [Delta]Hvap. Greater partitioning was observed for coplanar and mono-ortho PCBs. The utility of KOA as a particle-gas partitioning descriptor was tested using results from Chicago air samples. The particle-gas partition coefficient, Kp, was calculated and plotted against KOA and against the subcooled liquid vapor pressure, p°L. Log-log plots of Kp versus P°L showed enrichment for the coplana PCBs and PAHs. This enrichment was resolved by KOA for the coplanar PCBs but only partially resolved for the PAHs. A KoA-based absorption model of particle-gas partitioning was compared with the Junge-Pankow adsorption model. The KOA model provided a better fit for PCBs but not PAHs, which were underestimated. An advantage of the KOA model is that it only requires knowledge KOA and the fraction of organic matter on the particle which are both easily measured. The Chicago field study led to the investigation of a new compound class, PCNs. A method was developed for quantifying PCNs based on the FID response of individual congeners in Halowax 1014, a technical mixture of 2 to 8-Cl congeners. PCNs were quantified in air samples from Chicago and three Arctic locations--a cruise track of the Eastern Arctic Ocean, Alert (Canada), and Dunai Island (Russia). The results show that PCNs contribute significantly to dioxin-type toxicity in air and merit further study. A review is made of the transport processes, concentrations, and implications of organochlorine contamination of the Canadian Arctic. Speculations are made regarding the relationships of global warming, physical chemistry of the compounds, and future trends of contaminants.
A boundary condition coupling strategy for the modeling of metal casting processes

A generalized temperature boundary condition coupling strategy for the modeling of conventional casting processes was implemented via experiments and numerical simulations with cylindrical aluminum, aluminum alloy and tin specimens in copper, graphite and sand molds. This novel strategy related the heat transfer coefficient at the metal-mold interface to the following process variables: the size of the air gap which forms at the metal-mold interface, the roughness of the mold surface, the conductivity of the gas in the gap, and the thermo-physical properties of both the metal and mold. The objective of this study was to obtain, apply and evaluate the effect of incorporating an experimentally derived relationship for specifying transient heat transfer coefficients in a general conventional casting process. A systematic experimental approach (not limited to a specific industrial process) was implemented to determine the heat transfer coefficient, and characterize the formation of the air gap at the metal-mold interface. The heat transfer mechanisms at the interface were identified, and seen to vary in magnitude during four distinct stages, as the air gap formed and grew. An semi-empirical inverse equation was used to characterize the heat transfer coefficient-air gap relationship, across the various stages, for experimental data from the literature and this study, and a correlation was presented in non-dimensional form for experimental data from this study. The effect of surface roughness was observed to be pronounced at small relative gap sizes, reducing the heat transfer coefficient at least one order of magnitude below that predicted for perfectly flat surfaces. The effect was observed to progressively diminish with increasing gap sizes, and approached an analytical 'perfectly flat' solution for larger gap sizes. A simplified visco-elastic plastic numerical model was developed for a cylindrical coordinate system to predict the growth of the air gap. The model's predictions of the gap growth compared well with the experimental measurements for each system examined. Application of the correlation via coupling with the energy equation was seen to improve the accuracy of an uncoupled casting model, bettering the predicted air gap formation, and eliminating the previously existing time lag for initial formation of the gap.
The impact of long-term psychotherapy on the social activism of social activists

Are the process and goals of psychotherapy antithetical and inhibitive to the process and goals of social activism? Does the individual focus of psychotherapy detract from the external focus of socially based theories and actions by personalizing, depoliticizing, and ultimately perpetuating inequitable social conditions? In this descriptive research, activists who had been activists before and after at least two years of insight-oriented psychotherapy were asked to discuss how they believed their psychotherapy experience impacted their social activism. Fourteen social activists were interviewed by means of a semi-structured interview format. Data analysis was based on a theme development process. All 14 respondents reported that psychotherapy had improved their self-care skills, that their activism was suffering before therapy because of the weakness of these skills, and that the improvement enabled them to become more effective activists. Four aspects of effectiveness emerged: practical abilities, emotional capacity, intellectual understanding, and spiritual connectedness. All respondents cited improvements in two or more of these aspects. Participants were specifically asked if they believed themselves any less radical than before therapy. Thirteen participants did not think their radicalness had changed. This conclusion was supported by an examination of the activists' theory statements. The activists' positive experiences with psychotherapy did not translate into a general endorsement of psychotherapy. The participants believed that their experiences were largely the result of their choice of therapist. Almost all had worked with therapists (mostly feminist therapists) who included socially based explanations in their understanding of individual problems. These particular therapists helped the activists to incorporate their personal selves into their political fives allowing them to stay committed to their activism and enabling them to access practical, emotional, intellectual, and spiritual resources so they could participate in their activism more holistically. The findings strongly suggest that social activism requires a holistic approach and that certain kinds of psychotherapy can play a significant role in improving the effectiveness of social activists. There are implications for activists, social activist organizations, and psychotherapists.
Content validity assessment of the University Student Health Survey Instrument

This study examined the content validity of the University Student Health Survey Instrument (USHSI) which was adapted from a health survey instrument that had been used in a large urban university and also included questions based on relevant research findings. The USHSI was organized according to the Determinant of Health dimension of the Population Health Promotion Model (PHPM) (Hamilton & Bhatti, 1996). The study sample included twenty two students who participated in focus group discussions and nine staff/faculty who participated in individual interviews. The participants were asked to assess the content validity of the USHSI using Lynn's (1986) content validity index (CVI) rating scale and to respond to three open-ended questions. The total CVI rating for the USHSI was 0.84 indicating that the instrument showed evidence of content validity. Based on the study's findings, five questions were eliminated, five questions were modified and twelve questions were added to increase the content validity of the USHSI. Social support networks and health services emerged as important determinants of health that were not addressed in the initial USHSI. Implications for research theory and nursing practice are discussed. This research is an initial step which could lead to a greater understanding of the health behaviours and the determinants of health of university students.
Currents and fields of CN Tower multistroke lightning flashes

The CN Tower in Toronto provides an excellent sight for the study of the lightning phenomenon. Simultaneous measurements of currents and fields to the CN Tower have been performed since 1991. One of the most interesting features of lightning is the multiplicity of strokes within many lightning flashes, which means that the lightning flash could contain a number of successive discharges. Studying this phenomenon is of great importance as it should be taken into account when designing protection means for power systems and for EMC purposes. In this thesis both currents and magnetic fields of multistroke lightning events to the CN Tower are studied in detail in order to obtain statistical information about subsequent strokes in relation to the first stroke of a flash. The thesis provides statistics for each year for both current and magnetic field wavefront parameters. Besides, a subset of the whole data is studied that contains only field and current files which correlate to each other. In this case both current and field measuring systems were successful to trigger simultaneously and capture the current and the accompanying field waves.
Solution structure and electrostatic properties of an SH2 domain/phosphopeptide complex

SH2 domains are small (~100 amino acid) protein recognition domains found in numerous proteins involved in signal transduction which bind to sites of tyrosine phosphorylation with high affinity in a sequence-dependent manner. We have focused on the SH2 domains of phospholipase C-ã (PLC-ã), which provide a link between activated growth factor receptors via binding through its two SH2 domains and the production of the second messengers IP3 and DAG. The interaction of PLC-ã with the platelet derived growth factor receptor (PDGFR) is at sequences about Tyr 1021 of the PDGFR, and disruption of this interaction results in decreased cell growth following growth factor stimulation. Binding studies using degenerate phosphopeptide libraries suggest that this interaction involves the C-terminal (PLCC), and not N-terminal (PLCN) SH2 domain of PLC-ã. Thus we have studied this interaction involving the PLCC SH2 domain and a 12 amino acid phosphopeptide representing sequences about Tyr 1021 using heteronuclear NMR techniques. I was involved in the cloning and purification of this SH2 domain and preparation of NMR samples of this protein/peptide complex. A full structural determination was performed on this complex in collaboration with Dr. Steve Pascal. During structure determination, I defined the conformation of the phosphopeptide in this complex, as well as demonstrating protein-peptide contacts. Protein/peptide NOEs involving pTyr resonances defined a large positively-charged pocket containing four arginine residues which bound this residue. NOEs could not define contacts with the pTyr phosphate group, and we used large downfield chemical shift changes of guanidinium group resonances to do so. pH titration studies demonstrated that the pTyr phosphate group is bound in the -2 charge state with several residues held in place to facilitate pTyr binding by a complex hydrogen bonding network. A large hydrophobic cavity on the SH2 domain surface bound six residues C-terminal to pTyr, and in particular, the Ile +1 and Pro +3 residues were deeply buried. Thus a combination of NMR techniques involving NMR assignment, structure determination and pH titration studies provided significant insights into the specific binding of SH2 domains.
The child protection system, organizational responses to child sexual abuse and the social construction of social problems

The following dissertation is an examination of the relationship between professional policies and practices employed by the Canadian Child Protection system regarding child sexual abuse and the historical social constructions of child sexual abuse as a social problem. The research draws on constructionist and feminist theoretical perspectives and employs a critical interpretive analysis designed to expand our understanding of the relationship between the formal structure, policies, and practices of organization and the process of social problem construction. Two separate conceptual models were developed for the purposes of data organization and analysis. The first, 'The Process of Social Problem Construction Model' was developed and utilized to conceptually frame the analysis of a wide-range of theory, research, and historical data relating to the social construction of child sexual abuse as a social problem. The second model, a 'Three-Part Conceptual Model for Organizational Analysis' was developed specifically to facilitate a critical examination of 'relationship' and a textual analysis of the formal organizational/institutional structures, policies, and practices established by the current official documentation and legislation governing the delivery of child protection services. A system of coding was developed using the relationship dimensions delineated in the 'Three-Part Model for Organizational Analysis' enabling an examination of the connection between specific elements of the official child protection documentation and specific elements of the historical social construction framework and process. The inclusion and analysis of transcripts obtained from personal interviews with eight study key informants served to greatly enrich the analysis of the official organization documentation, legislation, and historical data. Finally, application of the techniques for establishing the trustworthiness of naturalistic inquiry offered by Lincoln and Guba (1985) greatly assisted in establishing the credibility, transferability, dependability, and confirmability of the research methodology. Recommendations are offered regarding the direction of future research in the area of child sexual abuse as well as proposed initiatives for social work educators and professionals.
Models for variable and age-dependent penetrances in genetic linkage analysis

An important factor in genetic linkage analysis is the penetrance, or the probability of disease onset given the genotype. The impact of variable and age-dependent penetrance on nuclear family linkage analysis and on sib-pair analysis is examined. In nuclear families, a systematic evaluation of the effects of penetrance misspecification for age-dependent models is reported. Bias in the estimate of disease gene location, and the loss in power associated with poor penetrance estimates are evaluated, and some guidelines are recommended. When the disease cannot occur in the absence of a particular gene (a necessary gene), it is shown that the estimate of gene location is nearly orthogonal to the parameters of the age-dependent onset functions when the recombination fraction is small. In sibling pairs, one methodology available for testing for linkage involves estimating the identical by descent allele sharing, and calculating a likelihood ratio test for deviations of the sharing from null values. This approach is extended to allow for variability in linkage evidence with covariates. The performance of this extension is evaluated through simulations, and these show that the power to detect linkage can be increased with covariates. In addition, covariate models provide flexibility and greater understanding of the disease process, and allow the detection of gene-environment interactions. A second extension of sibling pair methodology allows information from unaffected siblings to be used when testing for linkage. Because unaffected siblings may develop disease in the future, penetrance corrections must be included which allow for potential disease susceptibility, but the extended model has considerable robustness to misspecification of the susceptibility parameters. Some power improvements are seen in simulations. Empirical methods to estimate the significance levels when testing for linkage or heterogeneity are also developed.
Unusual retrograde condensation and asphaltene precipitation in model heavy oil systems using x-ray imaging

In this thesis, an accurate partial phase diagram for the model heavy oil system athabasca bitumen vacuum bottoms (ABVB) (24.6 wt. %/2 mole %) + dodecane (73.8 wt. %/47 mole %) + hydrogen (1.6 wt %/51 mole %) was constructed in the temperature range 425 K to 725 K and the pressure range 2 MPa to 7 MPa using a novel x-ray view cell apparatus. This model heavy oil fluid system is shown to exhibit L1V and L1L2V phase behaviour over parts of this P-T region. The phase boundaries separating these regions are shown to be reversible within 2 K and 0.03 MPa. The shape of the low temperature boundary between the L1V and L1L2V zones is characteristic of dilute asymmetric mixtures where on isothermal compression a heavy liquid phase, L2, appears then disappears within the light liquid phase, L1. Such phase behaviour is referred to as unusual retrograde condensation and is of both practical and theoretical interest. For this mixture the retrograde condensation extends over a 75 K and 2 MPa temperature and pressure range, respectively. This is only the second reported large scale example of such phase behaviour. Of equal importance is the finding that irreversible phase transitions involving asphaltene precipitation arise within the L1L2V region and not in the L1V region--even at higher temperatures. Transitions between the multiphase regions were found to be reversible at temperatures less than 655 K, in all cases. At higher temperatures irreversible "asphaltene precipitation" arose within the L2 phase. "Asphaltene precipitation" did not arise in the absence of the L2 phase, i.e.: within the L1V region, even at temperatures in excess of 700 K. These data provide a strong link between "asphaltene precipitation" and multiphase behaviour, and demonstrate a physical rather than a purely kinetic basis for asphaltene precipitation at elevated temperatures. This result compels one to rethink the approach to the modelling of such systems from both a phase behaviour and reaction kinetics perspective. A third important result for this work is the development of a variable volume view cell suitable for studying the phase behaviour of opaque hydrocarbon systems and other systems. This device, created in collaboration with D. B. Robinson Ltd., greatly simplifies phase behaviour experiments and allows one to work with small volumes of fluid over a broader range of temperatures and pressures (0.1-27.5 MPa, 290-750 K). The apparatus is being considered for commercialization.
In vitro characteristics of intimal cells at intercostal ostia in the porcine thoracic aorta

In humans, atherosclerotic plaques tend to develop immediately downstream of branches in areas of eccentric intimal thickening. Organ cultures of porcine thoracic aorta intercostal branches were used to study the reaction of branch point intimal cushion regions as well as unbranched regions to injury. Preliminary studies using both bromodeoxyuridine (BrdU) labeling and proliferating cell nuclear antigen (PCNA) localization revealed a significantly higher degree of intimal cell proliferation at the flow divider (BrdU: 9.5 $\pm$ 2.7%; PCNA: 12.2 $\pm$ 2.7%; n = 3) than on its opposing wall (BrdU: 3.9 $\pm$ 2.9%; PCNA: 6.3 $\pm$ 4.0%; n = 3) at 4 days. Further experiments have confirmed this difference in day 4 culture and have determined it due to increased endothelial (p $<$.05; n = 14) as opposed to smooth muscle cell proliferation. However, endothelial cell number did not differ significantly between opposing walls of the branch in 4-day cultures, suggesting increased cell death at the flow divider. This was confirmed quantitatively by the live/dead assay and supported by TUNEL labeling. Tissue culture studies suggest that endothelial cells isolated from branch regions have a decreased capacity to effect wound repair. which may be due in pan to decreased migration as opposed to proliferation, although cytoskeletal analysis revealed no obvious differences in wounded cells. These findings may indicate the existence of endothelial cells that differ in terms of their intrinsic responses to injury in organ and tissue culture, characteristics which may play a role in vivo, in the development of atherosclerosis-prone regions in the arterial vasculature.