VictorJuiz/thesis huggingface dataset:
Determination of hydrogen concentration in Zr-2.5% Nb pressure tube material by high frequency nonlinear ultrasonics

To a first-order approximation, ultrasound behaves in a linear manner when travelling through a solid material. However, if we consider the lattice anharmonicity, different types of nonlinear phenomena appear. In certain cases, these non-linear effects can be valuable indicators of material properties. The goal of this study is to determine whether non-linear second order harmonic generation can be used to indicate the concentration of hydrogen (deuterium) in CANDU nuclear reactor pressure tubes. Two high-power ultrasonic waves, at frequencies up to 200 MHz, are required for this purpose; the two sound beams combine in a non-linear wave-wave interaction that is measured by piezoelectric crystals mounted onto test specimens. The magnitude of this nonlinear second order harmonic is measured in five pieces of Zr-2.5% Nb pressure tube which contain different levels of zirconium hydrides. Unfortunately, no consistent trend was found in the amplitude of the observed nonlinear effect versus hydrogen concentrations.
Mechanism and electrostatic acceleration of 2-(1-hydroxybenzyl)thiamin fragmentation

The condensation of thiamin and benzaldehyde gives 2-(1-hydroxybenzyl) thiamin (HBzT). Methylation of HBzT gives 1$\sp\prime$-methyl-2-(1-hydroxybenzyl) thiamin (MBzT). MBzT fragments irreversibly in water to form a phenyl thiazolyl ketone (PTK) and a dimethyl pyrimidine (DMP). The difference between HBzT and MBzT is a single fixed charge at the N$\sb1\sp\prime$ position of MBzT. This charge may promote the fragmentation of MBzT in several ways. If the transition state is carbanionic in character, inductive or resonance stabilization by electron-withdrawing substituents on the pyrimidine portion should increase the rate of fragmentation. However, this is not observed for the electron-withdrawing nitrobenzyl analogues that were studied. Thus, since fragmentation occurs only if N$\sb1\sp\prime$ is charged, a significant electrostatic effect is necessary to lower the barrier to fragmentation. In contrast, benzoylformate decarboxylase uses HBzT pyrophosphate as an intermediate without fragmentation. Thus, the active site should suppress fragmentation, perhaps by specifically stabilizing charged structures. Finally, the detailed pathway of fragmentation appears to involve an unprecedented 1,2 proton transfer from nitrogen to carbon. This deserves careful examination. Ab initio studies evaluate the feasibility of various routes for this proton transfer. In addition, analogues of MBzT focused attention on the portion of the molecule that control the fragmentation.
Health status measures for predicting postoperative length of stay out of hospital following lung resection via thoracotomy

We investigated the hypothesis that preoperative assessment which included a multidimensional health status measure (HSM), when added to FEV$\sb1$, DLco and 6-minute walk test, would enhance the ability to predict postoperative outcome as assessed by length of stay out of hospital (LOSOH) in lung resection patients. HSM was evaluated by the EORTC QLQ-C30 questionnaire (global quality of life (QL), social function (SF) and emotional function (EF) scales). For the entire sample (n = 70), none of the 6 independent variables evaluated was predictive of LOSOH, while age was a significant predictor. 4 subjects suffered extreme outcomes (LOSOH= 0-5 days), with age the sole factor differentiating these subjects from those with less extreme outcomes (LOSOH= 14-26 days, n = 66). In these 66 subjects, QL score and 6-minute walk distance were the strongest predictors of LOSOH. HSM shows a limited ability to predict LOSOH in patients undergoing lung resection.
Combination of hydrogel and liposomes as a responsive drug delivery system

The idea of combibing hydrogel and liposome as a responsive drug delivery system was investigated. Two hydrogels, one as a static network and the other as a gellable solution, were formulated. Poly(vinyl alcohol) was chosen as the static network and gellan gum as the gellable solution. Results fiom light microscopy and DSC measurements had shown that liposomes were formed within the PVA hydrogel. The release of different solutes from PVA hydrogel with or without liposomes were examined. It was found that the existence of liposomes was able to extend the release period and increase the loading capacity of lipophilic solutes. The release rate of the solutes were responsive to temperature variation. The vitreous was selected as a model site for injection of the gellable solution. Simulation of intravitreal injection had shown that the gellable solution was able to gel within the injected site and encapsulate liposomes inside the gel.
The lived experience of women with preterm premature rupture of the membranes, PPROM, who remained at home until delivery of their infants

Purpose. The purpose of this study was to describe the lived experience of women with PPROM who remained at home until delivery of their infants. Method. The experiences of five women at home with PPROM were explored using unstructured interviews. The data were analysed using a method consistent with phenomenological research. Results. Three dominant themes evolved from the data: (1) feeling overwhelmed at the initial diagnosis, (2) the struggle to achieve a balance, and (3) movement towards living a normal life. The third theme illustrates the dynamic process the women used to adapt to PPROM and was described in two subthemes: (1) the importance of support and (2) becoming an expert knower. Conclusion. The women's descriptions of their experiences revealed their initial response of feeling overwhelmed by their diagnosis, the struggles they had with their situations, and how they were able to move towards living a normal life with PPROM.
The relationship among attention deficit hyperactivity disorder, learning disability, and central auditory processing disorder

Confusion and controversy regarding the definitions of attention deficit hyperactivity disorder (ADHD), learning disability (LD), and central auditory processing disorder (CAPD) have persisted despite their frequent use in classifying children in educational settings. Differential diagnosis of CAPD appears to represent a particular concern among a variety of professions, including audiology, speech-language pathology, psychology, and education. This study was conducted to determine if several assessment procedures addressing a child's academic, cognitive, and behavioural status would discriminate children identified with an attention deficit disorder, a learning disability, or a combination of these two disorders. We also attempted to determine if these children could be differentiated on the basis of their performance on measures of central auditory processing abilities. The test battery included the SCAN (a screening test for auditory processing disorders), the Auditory Continuous Performance Test (ACPT), the Children's Auditory Performance Processing Scale (CHAPPS), the Conners Parent Questionnaire, the Wide Range Achievement Test (WRAT-3; Reading and Arithmetic subtests), the Listening Comprehension subtest of the Wechsler Individual Achievement Test, and three subtests of the Wechsler Intelligence Scale for Children - Third Edition. The results indicated that there is a significant, though not mutually inclusive relationship between ADHD and CAPD. Moreover, a proportion of children in all three groups (NA, LD, ADHD) demonstrated auditory processing difficulties. Although there were significant correlations among tests and groups, there was also much variability within each particular group. An interdisciplinary approach to the identification of auditory processing disorders in children with learning difficulties was emphasized.
An evaluation of the odds ratio as an estimator of vaccine efficacy

The retrospective case-control study has often been sought as a quicker, less expensive alternative to the prospective cohort study in the evaluation of vaccine efficacy. Unlike the prospective study, which compares attack rates or susceptibility in the vaccinated and unvaccinated, the case-control study compares vaccination odds in diseased and non-diseased. When the disease is rare this poses little problem. But, when disease incidence is high or vaccine efficacy is low, the odds ratio tends to overestimate vaccine efficacy. Using the models of vaccine action introduced by Smith et al. (1984) we examine the odds ratio under two sampling schemes for selecting controls. Epidemic simulations of uniformly mixing and stratified populations are used to examine the estimators when vaccination coverage is evenly distributed or clustered to varying degrees. Finally, results from both prospective and retrospective efficacy trials of Haemophilus influenzae b vaccines are discussed in light of the findings.
Application of ecological interface design to aviation

The objective of this thesis is to determine the extent to which previous research on Ecological Interface Design (EID), conducted in the context of process control, can be adapted to design more effective status displays for engineering systems in aviation cockpits. The primary outcome of this research is a prototype EID interface for the engineering systems of Hercules C-130 Model E-H aircraft. This thesis includes the currently available literature on aircraft status display design, principles of EID, previous EID research conducted by the Cognitive Engineering Laboratory at the University of Toronto, two field studies observing Canadian Armed Forces (CAF) Hercules crews, analysis and design of the prototype EID interface, an evaluation of the prototype conducted with CAF Hercules C-130 Flight Engineers, and a comparison of the operating philosophies inherent to EID and those currently existing in the aviation industry. The results of this study provide a proof of concept showing that: (a) the principles of EID can be meaningfully applied to the aircraft engineering systems of a Hercules C-130; (b) EID needs to be supplemented by more specific design principles; (c) it is possible to effectively integrate EID with these other design principles. In conclusion, EID has been shown to be a viable candidate for the design of engineering systems status displays within the aviation industry.
Studies on the molecular basis of crosslinked mIgM interactions with the cytoskeletal matrix

Numerous studies have shown that crosslinked B cell antigen receptor (BCR) interacts with the cytoskeletal matrix. Previous studies have pointed out that the BCR-cytoskeletal interactions are positively correlated with B cell proliferation and capping, suggesting that the interactions play a role in B cell activation. To elucidate the function of the BCR-cytoskeleton interactions, it is necessary to delineate the molecular basis of these interactions. The experiments reported here addressed the following questions: (1) Which component of the BCR is required for the interactions of mIgM (surface form of IgM) with the cytoskeleton? (2) What site on the mIgM molecule mediates the interactions with the cytoskeleton upon crosslinking? By investigating the mIgM-cytoskeleton interactions in the human cervical carcinoma cell line HeLa S3, I report here that neither Ig-$\alpha/\beta$ nor any other B cell specific protein(s), are important in mediating the interactions. Furthermore, by taking, advantage of a IgM molecule in which the cytoplasmic tail of IgM, KVK, is replaced by that of Ig-$\alpha,$ I also report here that the KVK sequence of mIgM is important for the interactions between mIgM and the cytoskeleton. The absence of KVK does not, however, completely abrogate the mIgM-cytoskeletal interactions, suggesting that KVK has a substantial, yet not essential role for these interactions.
A guideline for the design of a four-wheeled walker

More people use assistive technology devices to compensate for mobility impairments than for any other general type of impairment. Increasing numbers of people with mobility or balance problems use walkers with four wheels. Four-wheeled walkers are often outfitted with seats so that it is possible to travel longer distances with intermediate resting periods. The dangers of sitting on a parked walker are well known. Many physiotherapists actually tell walker users to park the walker against a wall to prevent injury in case the user forgot to apply the brakes, or the brakes fail. To design a safer walker used for sitting, the demands placed on a walker must be measured. With these data, 3 modes of walker failure must be considered. The first mode is that the brakes may hold but the wheels slide along the ground. The second mode of failure occurs when the entire walker tips over. The third is brake failure in which the brakes cannot hold the wheels in place and they begin to roll. Mathematical models can be constructed that simulate how different walker designs will perform. By this process, design improvements can be made for existing walkers and future walker designs can also be proposed.
The effects of gaze-contingent windows on detection of peripheral targets

Foveated displays achieve large computational savings by providing high resolution imagery only where the viewer is looking, and degraded imagery elsewhere. Applications of foveated displays are discussed. Area-of-interest (AOI) displays are used in flight simulators and consist of a high-resolution window within a low-resolution background. If the edges of the window are perceptible, they could cause impairments in detection of peripheral targets. Experiment 1 examined the effects of two different types (high resolution and bright) of windows on detection of moving targets. Windows impaired target detection, and the impairment was partly due to the visible edges of the windows. Experiment 2, examining the effects of window size on detection of static targets, found no size effects. The results are discussed in terms of tunnel vision and general interference accounts of impairment of peripheral tasks.
Interfacial degradation of carbon fibre reinforced polyetheretherketone, PEEK

Single fibre pullout tests were used to determine the hot water effect on the interphase of carbon fibre reinforced polyetheretherketone (PEEK). Shear stresses were calculated according to the experimental results for each group of samples and were used to compare the environmental effects on the interfacial strength. Pullout phenomena observed in this work were discussed. Two slope change points were observed on most pullout curves achieved in this work. Experimental results agree with Piggott's theory in which the two slope change points were believed to be results from the matrix yielding and the debonding initiation. It was indicated that the simple "double line treatment" might be good enough for the carbon/PEEK system. The interphase between the carbon fibre and the PEEK resin was found to have a very good resistance to hot water attack. There was no significant influence of immersion in 60$\sp\circ$C distilled water on the interfacial strength before 1000 hours. Immersion in 90$\sp\circ$C distilled water caused slight degradation of the interfacial strength. The interfacial strength can be degraded up to about 30% after immersion in either 60$\sp\circ$C or 90$\sp\circ$C distilled water for 1000 hours. Further exposure, up to 3000 hours, does not further aggravate the degradation. Moreover, the loss of the interfacial strength cannot be recovered after thorough desiccation.
The experience of caring for people with AIDS

The purpose of this phenomenological study was to describe nurses' experiences of caring for people with AIDS. Five nurses working on a general medicine/surgical unit, which included patients with AIDS, described their experiences in two unstructured interviews each. Findings revealed that the nurses developed a professional and a 'friendship-like' relationship and consequently found themselves advocating for the patients' needs, defending their homosexual lifestyle and right to the care they wished as they were dying. The nurses also expressed the importance of supporting and meeting the needs of the family, friends and lovers. Occasionally, negative statements and discomfort associated with homosexuality were expressed. Implications for future research and clinical practice are suggested.
Defining sites of interaction in the Ã-chain of C3 for factor H, membrane cofactor protein (MCP), and complement receptor 1 (CR1)

The goal of this thesis was to identify sequences in human complement component C3 that contribute to its interaction with several of its regulatory molecules. Several groups have implicated residues within the 727-767 segment at the N-terminus of C3b $\alpha\sp\prime$-chain as being important for its interactions with the regulatory molecules factor H and complement receptor 1 (CR1), as well as the alternative pathway component factor B. This laboratory had previously identified residues 736$\rm\sp{E}$ and 737$\rm\sp{E}$ as being important for both factor B binding and CR1 binding, but mutation of these residues had little or no effect on factor H binding. I conducted a charged residue to alanine mutagenic scan between residues 741 and 767. Recombinant molecules were transiently expressed in COS-1 cells and were examined for their interaction with factor H using a factor I-mediated cleavage assay that was dependent upon prior complex formation between the C3b-equivalent molecule C3(H$\sb2$O) and the I-cofactor, in this case factor H. This approach identified the negatively charged side chains of residues 744$\rm\sp{E}$ and 747$\rm\sp{E}$ as being important for the binding interaction with factor H. The 727-767 series of mutants were further examined for their interactions with soluble forms of CR1 and MCP. In addition to confirming that residues 736,737$\rm\sp{EE}$ play a role in the CR1 interaction, I have further identified residues 747$\rm\sp{E}$ and 754,755$\rm\sp{ED}$ as being similarly important for this interaction. Residues 744$\rm\sp{E}$ and 757,758$\rm\sp{KE}$ also appeared to contribute to this interaction, although to a lesser extent. Thus, although the factor H and CR1 sites of interaction within the 727-767 segment appeared to overlap, the negatively-charged residue contacts required for CR1 binding appeared to be more extensive than those for factor H. None of the mutations had any effect on the binding with MCP, suggesting that the N-terminal $\alpha\sp\prime$-chain segment plays no role in this interaction. (Abstract shortened by UMI.)
An investigation of air-water gas transfer in Lake Ontario

It has been shown that bubbles entrained by breaking waves can enhance air-water gas transfer and cause the supersaturation of some gases in water. A new model of air-water gas transfer is presented that synthesizes previous models and includes the effects of bubbles entrained by breaking waves. The predictions of the new model and existing models are compared to field measurements of dissolved oxygen levels that were observed in Lake Ontario from September to December, 1995. The new model out-performs previous models. Results from the model show that bubbles can play an important role in gas transfer for less soluble gases like oxygen and carbon dioxide, but not for more soluble gases like HCB and Lindane. Also, the less soluble a gas, the more important it is to have accurate estimates of model parameters such as bubble population shape, average entrained bubble depth, and the influence of surface active materials.
A transforming mutation induces dimerization and enhances activity of the c-kit soluble tyrosine kinase domain

An activating mutation (DY814) located in the catalytic domain of the c-kit receptor has been found in mastocytomas. I characterized purified WT and DY814 kinase domains expressed in Pichia pastoris. A Flag epitope was fused to c-kit cDNAs enabling purification with anti-Flag antibodies. Yeast expressing DY814, but not WT, contained multiple tyrosine phosphorylated proteins. The mutation was found to increase the apparent k$\rm\sb{cat}$ by 10-fold and decrease the apparent K$\rm\sb{m}$ for ATP by 9-fold. WT activity displayed a non-linear dependence on enzyme concentration that could be enhanced by anti-Flag antibodies. In contrast, DY814 activity dependence on enzyme concentration was linear and marginally enhanced by anti-Flag antibodies. The WT kinase migrated as a monomer in gel filtration whereas the DY814 mutant migrated as a dimer. These results indicate that DY814 promotes dimerization of the c-kit kinase, potentially contributing to its transforming potential.
Adaptive Backstepping Control of the Variable Reluctance Motor

In this thesis, both full-state and observer-based adaptive backstepping controllers are synthesized for the plant which uses splines to model its nonlinearity. It is hoped that the use of splines in the backstepping algorithm can alleviate the complexity of the resulting controller, but unfortunately, it is shown that this is not the case. A variable reluctance motor (VRM) is used as a testbed for these controllers. The full-state controller exhibits undesirable behavior, i.e., steady state tracking error and some excitation of high frequency dynamics. Because velocity of the motor is not directly measured, a linear filter is used to estimate the true velocity. It is believed that this is the cause of some of the undesirable plant behavior. An observer-based controller is implemented in order to test this conjecture. The observer based controller reduces the steady state error by half, and eliminates an audible hum produced by the motor in the full-state control case.
The regulation of metabolic coronary dilation and reactive hyperemia by nitric oxide in the isolated rat heart

The aim of this study was to observe if nitric oxide couples metabolic demand to coronary flow during metabolic coronary dilation and reactive hyperemia. Isovolumically, spontaneously-beating isolated rat hearts were perfused at constant pressure (Langendorff technique) with modified Krebs-Henseleit solution. Coronary flow responses to a 10 second occlusion and to various doses of noradrenaline, adrenaline, calcium chloride and pacing-induced tachycardia were measured under control conditions, after inhibiting endothelial nitric oxide production with L-NAME and after administering L-arginine, the precursor of nitric oxide. The results show that the coronary responses for both hyperemias decreased during inhibition and increased during enhancement of nitric oxide synthesis. Although some differences exist between the two coronary responses, this is likely due to a differing mechanism of response. Thus, the data suggest that coronary flow regulation during metabolic coronary dilation and reactive hyperemia is partially mediated by nitric oxide.
The structural testing and modification of a full-scale ornithopter's wing spars

This report details the structural testing of the wing spar and the modification of the wing design of a full-scale, human-piloted, engine-powered, flapping-wing aircraft known as the UltraLight Ornithopter, or ULO. The construction and the testing of three sample spars and the ULO wings are presented. The goal is to validate the theoretical wing design and demonstrate that a wing can be built to meet the requirements of sustaining flapping flight at 1.05 Hz.