VictorJuiz/thesis huggingface dataset:
Separate proliferation kinetics of FGF-responsive and EGF-responsive neural stem cells within the embryonic forebrain germinal zone

The embryonic forebrain germinal zone contains two separate and additive populations of stem cells that both exhibit self-renewal and multipotentiality. While cumulative S-phase labeling studies have investigated the proliferation kinetics of the overall population of precursor cells within the forebrain germinal zone through brain development, little is known about when and how (symmetrically or asymmetrically) the small subpopulations of stem cells are proliferating 'in vivo'. This has been determined by injecting timed-pregnant mice with high doses of tritiated thymidine (3H-TdR) to kill any stem cells proliferating within the striatal germinal zone ' in vivo' and then by assaying for neurosphere formation 'in vitro'. Injections of 0.8 mCi of 3H-TdR given every 2 h for 12 h to timed-pregnant mice at E11, E14, and E17 resulted in significant depletions in the number of neurospheres generated by FGF-responsive stem cells at E11, and by EGF-responsive and FGF-responsive stem cells at E14 and E17. With increasing embryonic age, the depletions observed in the number of neurospheres generated 'in vitro' in response to FGF2 following exposure to 3H-TdR 'in vivo' decreased, suggesting there is an increase in the length of the cell cycle of FGF-responsive neural stem cells through embryonic development. The results suggest that the FGF-responsive stem cell population expands between E11 and E14 by dividing symmetrically, but switches to primarily asymmetric division between E14 and E17. The EGF-responsive stem cells arise after E11, and their population expands through symmetric divisions and through asymmetric divisions of FGF-responsive stem cells.
The biological role of the hydrophobin cerato-ulmin in the life history of Ophiostoma ulmi and O. novo-ulmi

The causal agents of Dutch elm disease, 'Ophiostoma ulmi' (Buisman) Nannf. and 'O. novo-ulmi' (Brasier, 1991) both produce a hydrophobin called cerato-ulmin (CU). A CU over-expression mutant of the non-aggressive 'O. ulmi' H5 was constructed. The transformant produced considerably higher levels of 'cu'-specific mRNA and increased levels of CU protein. Analysis of greenhouse trials with American elm, 'Ulmus americana' L., suggested no alteration of virulence of this over-expressing transformant when compared to the non-aggressive H5. Over-expression of CU in the transformant led to an altered colony morphology which was manifested as an enhanced surface hydrophobicity, and a profusion of aerial hyphae. This study suggests that CU is a parasitic fitness factor. Our results demonstrate that CU production is correlated with increasing hydrophobicity, thus increasing the adherence of yeast-like cells to the bark beetle vector, ' Scolytus multistriatus'. Our results also demonstrate that CU is important in protecting infectious propagules from environmental stress.
Learning ESL in a Canadian Senior-Public school, an ethnographic and sociolinguistic study

This dissertation, based on a 15-month ethnographic and sociolinguistic study of English as a Second Language (ESL) learning in a Senior Public school in Toronto, examines how students learning ESL are subject to institutional relations of power and asks whether and to what extent ESL student practices reproduce these unequal power relations. In this dissertation I draw on two overlapping senses of the concept of 'practice' as it is used in anthropology and in theories of second language acquisition. The first sense of practice comes directly from an interactionally-based model of second language acquisition. Proponents of this model argue that the acquisition of language skills results from learners practicing the target language. In this dissertation I examine the social factors that affect ESL students' ability to practice speaking English, both in the classroom as well as outside the classroom among 'peers' in situations where other languages are potentially spoken. The second sense of practice comes from contemporary social theory, where scholars seek to understand the complex role of practices in the (re)production of social and cultural structures. This dissertation examines the mechanisms by which the unequal social relations between minority and majority language speakers in Canada are reproduced through everyday practices. I show how ESL students' ability to practice speaking English is subject to the teacher's institutional mandate to control student activities (including talk) in the ESL classroom setting. In other words, ESL students' ability to learn English (and by extension their ability to access the power that this dominant variety represents) is systematically limited by the teacher's power to control talk in the classroom. I also examine the role that ESL students, as a subordinated group, play in the reproduction of power structures. I found that ESL students act in ways that indicate recognition of the unequal structures of power to which they are subjugated. Furthermore, ESL students often draw on and reproduce these power inequities in interactions with other ESL students. However, at other times ESL students act in ways which appear to evade the power relations which constrain the process of learning ESL in this school setting.
Broadband high-fidelity directional transient couplers

A review of coupling theory is compiled with specific emphasis on the mechanisms present in a resistive directional coupler (RDC). An improved theoretical model for an RDC is developed, which can aid in the synthesis of more complicated designs than was allowed by a previously published model. With the use of this model, a general design procedure for an RDC is presented. Couplers for both stripline and microstrip environments are synthesized and their theoretical performances are validated with the use of commercially available electromagnetic simulators.
She works hard for the money, differences in the income of male and female general practitioners

Research studies have repeatedly demonstrated a gap between the income of male and female physicians. This thesis examines the gendered income for family physicians in Ontario based on a mailed survey conducted in 1996. The model is theoretically driven based on variables drawn from two theoretical perspectives--gender stratification and human capital. The thesis demonstrates that despite a sizeable increase in the number of women in medicine and broader social trends, there remains a persistent gender gap in the earnings of family physicians in Ontario, even when controlling for a large number of practice and family characteristics. Using a model which is a synthesis of two theoretical perspectives, a large proportion of the variance between men and women physicians can be explained. However, different factors appear to contribute to determining the income of male and female physicians and the importance of these factors may be different for each.
Seniors, life style change decisions and seasonal migration, a Canadian perspective

Every winter across North America a population of senior citizens, estimated to be in the millions, begins a familiar southernly trek to warmer, sunnier environments where they will stay for up to six months before beginning the long journey back to their northern homes. While previous studies make some suggestions about what it is that these seasonal migrants may be seeking, they have provided little understanding of how and why this decision is made, or what might precipitate it or lead to this life style change; nor have they documented the personal feelings, observations and stories of these seniors in their own words. This qualitative study proposes a conceptual framework for seasonal migration which posits that this is a phenomenon which stands on its own. A decision making cycle is proposed and five key themes are linked to each of the three stages: (a) leaving, (b) returning, and (c) repeating the process. Finding relating to the realities and perceptions of the linkages between activity and physical health, the environment, and psychological health are outlined, with implications for social policy and health care proposed. In particular, the benefits resulting from living in summer-like environments year-round are discussed, including the ability to move about freely day after day and not be subject to the physical health risks presented by inclement weather. New findings, such as the role of daughters, financial coping strategies, and implications for volunteer recruitment and retention, are presented and discussed, love of one's country is expressed with an unexpected and refreshing exuberance and is found to play a significant role in the decision to not become permanent residents of the winter host country. A new picture of who snowbirds are emerges from this study; these pragmatic adventurers are not just seniors who take extended vacations every winter. They are thoughtful planners who aim to maintain a certain level of equilibrium in their lives, who exhibit a continuing interest in the future, and who experience personal growth as they live life to the fullest.
Ring-opened poly(ferrocene)s, new directions and applications

A series of novel [2]ferrocenophanes with unsymmetrical C-E bridges, [Fe([eta]-C5Me4)([eta]-C5H4)CH 2ERx] (1, ERx = SiMe2; 2a, ERx = PPh; 2b, ERx = PMes; 3, ERx = S), has been prepared via the reaction of the PMDETA adduct of [([eta]-C5H4Li)Fe([eta]-C5Me 4)CH2Li] with Cl2ERx (E = Si or P) or S(SO2Ph)2. The least tilted compound, 1, was found to be resistant to thermal, anionic and transition metal catalyzed ROP. In contrast, the significantly more tilted compounds 2a, 2b and 3 were all found to polymerize thermally. Treatment of 3 with CF3SO3Me or BF3·Et20 resulted in the first example of cationic ROP for a transition metal-containing heterocycle. The synthesis of two novel carbostanna[2]ferrocenophanes, ([eta]-C 5Me4)([eta]-C5H4)FeCH2SnR 2, 5 (a: R = tBu, b: R = Mes) was achieved via the reaction of ([eta]-C5Me4)([eta]-C 5H4Li)FeCH2Li·xTMEDA with Cl2SnR 2 (R = tBu or Mes). X-ray diffraction analysis of these species revealed structures possessing moderate ring-tilt and attempts to induce thermal ROP of 5a-b proved to be unsuccessful. Reactions of 5a with strong acids resulted in the formation of the corresponding ring-opened species via selective ipso-Cp-Sn bond cleavage. The solution self-assembly of an organometallic-inorganic triblock copolymer, poly(ferrocenyldimethylsilane)-'b'-poly(dimethylsiloxane)-' b'-poly-(ferrocenyldimethylsilane), 6, was studied in n-hexane. TEM and AFM analysis of these micellar solutions revealed the presence of multiple micellar morphologies including novel flower-like supramolecular assemblies. Studies aimed at understanding the factors which govern the self-assembly of 6 in n-hexanes suggest that the ability of the PFDMS block to crystallize is critical in directing the formation of flower-like assemblies. Direct electrical measurements of poly(ferrocenylsilane) have demonstrated that these materials exhibit p-type conductivities of 10-4 to 10-6 S·cm-1 on exposure to I2. Arc discharge simulations have shown that thin film coatings of poly(ferrocenylsilane)s on Mylar effectively prevent negative charge accumulation. Well-defined poly(ferrocenylsilane) microspheres, PFSMS-1 and PFSMS-2, were obtained through the Pt(O) catalyzed precipitation ROP of dimethylsila[1]ferrocenophane and cyclobutylsila[1]ferrocenophane. The oxidation of PFSMS-2 with I 2 yielded surface oxidized poly(ferrocenylsilane) microspheres which underwent cooperative electrostatic self-assembly with negatively charged silica particles to form composite core-shell spherical aggregates. Pyrolysis of PFSMS-1 and PFSMS-2 monolayers at 600 and 900°C resulted in the formation of magnetic spherical ceramic particles.
Habitual physical activity and the association with disease severity and exercise capacity in cystic fibrosis, a pilot study

'Objectives'. To determine recruitment and compliance rates for the collection of habitual physical activity data, to profile trends in habitual physical activity patterns, and to determine if a positive relationship exists between lung function, habitual physical activity, nutritional status and exercise capacity in cystic fibrosis (CF) patients. 'Results'. Positive and significant correlation coefficients were demonstrated between habitual physical activity (HAES), lung function, nutritional status and exercise capacity. Patients reported significantly higher Total Activity scores (mild to vigorous physical activity) for a typical weekend day ('HAES', 8.0 ± 3.0 hours/day; 'Activity Diary', 4.8 ± 2.3) than weekday ('HAES', 5.7 ± 2.8; 'Activity Diary', 3.9 ± 1.2). The ' Total Activity score' for a 'typical weekday', derived from the HAES, was demonstrated to be a significant predictor of forced expiratory volume in one second ('FEV'1), the most important variable in describing CF lung disease. 'Conclusions'. These pilot study results will serve as the precursor for a longitudinal follow-up study that will begin to address the direction of the causal relationship between habitual physical activity and FEV1 in CF. (Abstract shortened by UMI.)
The geology, petrography and geochemistry of gabbroic rocks of the Pants Lake Intrusive Suite on the Donner/Teck South Voisey's Bay property, North-Central Labrador, Canada

The South Voisey's Bay property held by Donner Minerals Limited in North-Central Labrador hosts Ni-Cu-Co mineralization within gabbroic rocks of the Pants Lake Intrusive Suite (PLIS). Three drill holes from across the property were selected for study. Samples were analyzed for major, trace, rare earth elements and examined by petrographic microscope. The data suggests that two distinct intrusions make up the PLIS denoted as the North and South Intrusions. Geochemical comparisons to the Voisey's Bay troctolites indicates similar major element contents reflecting plagioclase-rich mineralogy, and trace element contents of Voisey's Bay are similar to the South gabbro units. Contamination sources are not obvious from data collected. All gabbros are chalcophile-element depleted when plotted on Cu/Zr and Cu/Hf diagrams. Sulphides would have settled out of a silicate melt, due to a contrast in density, perhaps in a previous chamber or feeder conduit.
Deposit removal from industrial turbines using blast cleaning

Blast cleaning is used to remove deposits from surfaces of industrial turbine components. The main goal of the thesis was to evaluate the aggressiveness of different blast media and provide the best combination of blasting parameters for effective cleaning while minimizing the component substrate damage. The blasting process was characterized by the media kinetic energy and power based on velocity and mass flow measurements. This made the experimental results independent of equipment and test conditions. A qualitative characterization of both individual and multiple impact sites established the mechanism of deposit removal from turbine surfaces. An assessment of deformation at the edges of turbine parts such as at blade and disc grooves was made to identify blast conditions that minimized substrate damage.
Nonpolar contributions to conformational specificity in assemblies of designed short helical peptides

A series of designed short helical peptides was used to study the effect of nonpolar interactions on conformational specificity. A consensus sequence was designed to contain a heptad repeat (abcdefg), yielding short helices (17 residues), with minimal interhelical polar interactions. Heptad positions a and d were occupied by all possible combinations of the hydrophobic residues Leu, Ile, or Val, and positions e and g were occupied by Ala, yielding a series of nine peptides. An experimental methodology was developed to characterize the nine peptides and their pairwise mixtures; the results indicated that a vast array of structural states were formed possessing different degrees of conformational specificity. In other work, the control of specificity has been linked to polar interactions. This work demonstrated that subtle changes in the configuration of nonpolar interactions can have a significant effect on the conformational specificity of oligomeric short helices.
Exploring multiple intelligences theory in the context of science education, an action research approach

Since the publication of 'Frames of Mind': 'The Theory in Practice', multiple intelligences, theory (Gardner, 1983) has been used by practitioners in a variety of ways to make teaching and learning more meaningful. However, little attention has been focused on exploring the potential of the theory for science teaching and learning. Consequently, this research study was designed to: (1) explore Howard Gardner's theory of multiple intelligences (1983) and its merit for making science teaching and learning more meaningful; (2) provide a forum for teachers to engage in critical self-reflection about their theory and practice in science education; (3) study the process of action research in the context of science education; and (4) describe the effectiveness of collaborative action research as a framework for teacher development and curriculum development. The study reports on the experiences of four teachers (two elementary teachers, one junior high teacher, and one high school teacher) and myself, a university researcher-facilitator, as we participated in a collaborative action research project. The action research group held weekly meetings over a five-month period (January-May, 1999). The inquiry was a qualitative case study (Stake, 1994) that aimed to understand the perspectives of those directly involved. This was achieved by using multiple methods to collect data: audiotaped action research meetings, fieldnotes, semi-structured interviews, journal writing, and concept mapping. All data were analysed on an ongoing basis. Many positive outcomes resulted from the study in areas such as curriculum development, teacher development, and student learning in science. Through the process of action research, research participants became more reflective about their practice and thus, enhanced their pedagogical content knowledge (Shulman, 1987) in science. Students became more engaged in learning science, gained a greater understanding of how they learn, and experienced a science curriculum that was more relevant and personalized. In addition, the action research process provided a feasible and effective forum for both curriculum development and professional development.
The evaporation and stability of a droplet in a finite system

The results of recent experiments indicate that a temperature discontinuity exists at a liquid-vapour interface undergoing steady evaporation. In order to investigate this phenomenon in an unsteady situation, an experimental apparatus that can study the evaporation of a single one-component liquid droplet in a finite system has been built. The measured temperatures predict the existence of a temperature discontinuity at the liquid-vapour interface in agreement with the previous experiments. The 'D' 2-law of droplet evaporation gives a reasonable estimate of the evaporation rate when the temperature discontinuity is considered. Using the measured temperatures and droplet size, the pressure in the vapour during the evaporation process can be predicted using Statistical Rate Theory. For each of 80 sets of measurements, the largest difference between the prediction and the measured value is 9 Pa (less than 0.5%). Adsorption on the surface of the confining volume is found to play a significant role in the evaporation process. The stability of a droplet in a finite system has been investigated theoretically with consideration of the solid-vapour interface. The results indicate that a stable droplet can exist if the pressure at which film-wise condensation is predicted to occur is greater than the saturation pressure. The stable equilibrium size has not been observed with the experimental apparatus, and this is attributed to the nature of the solid surface. However, a quasi-steady state has been observed, which could serve as a well defined initial condition for an evaporation experiment.
Effects of biofilm growth on water flow and solute transport through a glass parallel plate fracture

Hydraulic and tracer tests were performed to determine the effects of biofilm growth on water flow and solute transport through a glass parallel plate fracture. Using the equilibrium convection-dispersion equation to analyse pre-biofilm tracer curves, it was found that hydrodynamic dispersion (D) was proportional to velocity (v) raised to the power of 1.5. A new mixing term Ã ' was defined, where Ã' = D/v 1.5. This term was constant under pre-biofilm conditions. With biofilm growth, the hydraulic conductivity was reduced to 0.4% of its original value. Tracer transport was dominated by channels and lower-permeability zones of varying scales. The mixing parameter Ã' increased by one order of magnitude. The retardation factor increased by up to 20%, likely due to decreased small-scale non-equilibrium effects and possible sorption to the biomass. The mass balance aperture did not decrease with biofilm growth, suggesting that tracer diffused into the biofilm.
Multiple simultaneous specification (MSS) control of brushless D.C. motor and high-speed linear positioning system

This thesis summarizes an investigation of the application of Multiple Simultaneous Specification (MSS) control to brushless D.C. (BLDC) motor and high-speed linear positioning system. Simulation and experimental results illustrate the effect of MSS control on system behavior. First, the dynamic models of BLDC motor and linear positioning system are developed. Second, the dynamic models are then verified by performing simulation and experiments of open-loop and closed-loop control. By comparing the simulation and the experimental results, nonlinearity of BLDC motor is observed and discussed. Finally, the deficiency of Proportional-Integral-Derivative (PID) controller is discussed. The major shortcoming of PID controller is the need to tune the PID gains to satisfy desired performance specifications. In fact, if multiple performance specifications are considered simultaneously, tuning PID gains become very tedious and time consuming. A systematic way for finding the controller gains to satisfy the desired performance specifications simultaneously is needed. Therefore, MSS control method, developed by Dr. Hugh Liu and Prof. J. K. Mills, Department of Mechanical and Industrial Engineering, University of Toronto, is applied to the BLDC motor and the linear positioning system control. By conducting experiments, MSS control method is proven to be effective on controlling BLDC motor and linear positioning system to satisfy several desired performance specifications simultaneously. Thus, the need to tune controller gains is eliminated.