VictorJuiz/thesis huggingface dataset:
Functions of CD45 in TCR signaling in CD4§+CD8§+ double-positive thymocytes

T cell receptor (TCR) signals are essential for normal T cell development, and CD45 is thought to be essential for coupling TCR to the intracellular signaling machinery. However, T cell development is only partially compromised in CD45-deficient mice. This thesis describes a CD45-deficient CD4$\sp+$CD8$\sp+$ double-positive (DP) thymoma called 3T7. I show that in 3T7 cells and DP thymocytes CD45 is necessary for the TCR-induced protein tyrosine phosphorylation, as well as changes in CD5, RAG-1 and CD4/CD8 expression levels. However, co-aggregation of TCR and either CD4 or CD8 induced signaling events in a CD45-independent manner, providing a rationale for the developmental phenotype observed in CD45-deficient mice. Surprisingly, I found no differences in the overall phosphorylation state of Lck or Fyn in CD45-deficient cells versus CD45-positive cells. However, I show that loss of CD45 is accompanied by a hyperphosphorylation of TCR$\zeta$ in 3T7 cells and conversely a hypophosphorylation of TCR$\zeta$ in CD45-deficient thymocytes, providing one possible biochemical mechanism for the TCR signaling deficits described. Collectively, these observations provide a conceptual and experimental framework for understanding the role of CD45 in TCR signaling at the DP stage of T cell development.
Verification of radiation exposures in a case-control study of thyroid cancer

Self-reported medical radiation exposures of subjects in a case-control study of thyroid cancer were compared with medical records. Records were available for 52.4% of self-reports. Determinants of record availability included medical record source contacted, years elapsed since exposure, education and sex of respondent. The proportion of agreement between self-reported exposures and available medical records was 83.9%. Record source was a determinant of agreement, with agreement increased if physicians' records were accessed. The estimated odds of thyroid cancer associated with prior head and neck radiation, as determined by self-reports, medical records, and medically-verified data, were similar, suggesting that self-reports and their corresponding medical records produced comparable risk estimates. Results suggest that self-reported exposures, even from long-ago, are quite accurate and have the advantage of being more readily available than medical records. However, this study could not adequately evaluate the extent of under-reporting and thus, the completeness of self-reported exposures.
Metabotropic glutamate receptor expression in rat spinal cord astrocytes in vitro and in situ

Evidence in the literature suggests that activation of specific sub-types of metabotmpic glutamate receptors (mGluRs) may have neuroprotective properties following traumatic and ischemic central nervous system (CNS) injuries. In order to gain an understanding of the potential mGluR-mediated neuoprotective contribution of spinal cord astrocytes following spinal cord injury (SCI), the expression patterns of these receptors was studied both in vitro, in a novel spinal cord astrocyte culture system, and in the developing and adult spinal cord, in situ. The functional properties of Group I mGluRs on cultured astrocytes was also briefly explored. A clear understanding of when and where these receptors are expressed will allow the subsequent exploration of their biochemistry and physiology, and any potential neuroprotective properties following SCI.
Teaching pronunciation of Japanese long and short vowels, kinesthetic and computer-assisted visualisation approaches

The present study focuses on the distinction between Japanese long and short vowels in both production and recognition. Seven intermediate-level university students of Japanese as a second language participated in three individualised pronunciation-clinic sessions spread over three-four weeks. In the sessions, two techniques, computer-assisted visualisation and a kinesthetic approach, were used for assisting the students in controlling duration and pitch movement. Pre-tests and post-tests for recognition and production were given to assess the sessions. The findings are: (1) the sessions, which focused on pronunciation of long/short vowels, had positive effects on the distinction not only in production, but also in recognition; and (2) the sessions were most effective for errors with long vowels with a pitch rise, suggesting the effectiveness of drawing learners' attention to pitch movement for the mastery of Japanese long/short vowels.
Methodology for polymer supported synthesis towards combinatorial chemistry

This thesis is a summary of research conducted since September, 1995. It is divided into three chapters, Introduction, Results and Discussion, and Experimental. The research described is concerned with the development of methodology for polymer supported synthesis. New dithiol linkers for liquid-phase synthesis have been prepared by linking lipoic acid to polyethylene glycol derivatives. These linkers have been used to bind aldehydes to the polymer resin towards the application of Umpolung chemistry on the resin bound dithianes. The unique solubility properties of polyethylene glycol have been exploited to obtain both optimum reaction conditions and ease of purification. The potential application of this methodology to combinatorial chemistry has also been addressed.
Solid state deuterium nuclear magnetic resonance investigation of the interaction of positively-charged polyelectrolytes with negatively-charged lipid bilayer membrane vesicles

Deuterium nuclear magnetic resonance ($\sp2$H NMR) is an important tool for studying many characteristics of lipid bilayers, in particular membrane electrostatics. The use of multilamellar vesicles (MLVs) containing specifically choline-deuterated 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) produce $\sp2$H NMR spectra with quadrupole splittings $\rm(\Delta\nu\sb{Q}$'s) that reflect the overall membrane surface charge. This molecule has been termed a "molecular voltmeter" because of this characteristic response to membrane surface charge. When MLVs containing choline-deuterated POPC and the anionic lipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG) are exposed to cationic polyelectrolytes $\rm\Delta\nu\sb{Q}$ changes in a specific manner characteristic of the polyelectrolyte. A survey of the effects of several different polyelectrolytes was carried out and one response in particular was explored in detail, that being the response to poly(vinylbenzyltrimethylammonium chloride) (PVTA). This molecule was observed to induce the formation of two distinct domains. Through the combined use of spectral simulations and $\sp2$H NMR spectra, it was possible to accurately determine the composition of the two domains.
Pregnancy outcome following maternal organic solvent exposure, a meta-analysis of epidemiological studies

Evidence of fetal damage or demise from organic solvent levels that are not toxic to the pregnant woman is inconsistent in the medical literature. The risk for major malformations and spontaneous abortion from maternal inhalational organic solvent exposure during pregnancy was summarized using meta-analysis. Medline, Toxline and Dissertation Abstracts databases were utilized to search for all research papers published in any language from 1966 to 1994. Included were studies that were case-control or cohort in design and indicated first trimester (or up to 20 weeks gestation for spontaneous abortion) maternal solvent exposure. Research results were combined by the Mantel and Haenszel method. In total, 559 studies were obtained from the literature search. Five studies for each outcome of interest were included into the analysis. The overall summary odds ratio (ORs) for major malformations was 1.64 with a 95% CI of 1.16-2.30. The ORs for spontaneous abortion was 1.25 with a 95% CI of 0.99-1.58. These results indicate that maternal inhalational occupational exposure to organic solvents is not associated with an increased risk for spontaneous abortion. However, the significance of the results with regard to malformations warrants further investigation.
Teaching functions in the elementary years, a developmental approach

The concept of a function is an important one on which many higher order mathematical ideas depend. Traditionally, functions are introduced at the grade nine level, and research suggests that this topic is an extremely difficult one for students to learn. The purpose of the present study was to investigate the possibilities of teaching functions to two groups of grade six students (N = 20) using a developmental approach. An experimental curriculum was developed that included both classroom and computer activities and involved the integrated use of multiple representations of functions (i.e. graphic, algebraic, tabular, and verbal). Analyses of pre and post test measures showed that students improved significantly. The greatest change appeared on subskills that required translation among the multiple representations of functions, and application of the various representations. The findings suggest implications for including functions in the elementary mathematics curriculum.
Maternal authoritative discipline techniques, effects on children's and mothers' ratings of compliance, internalization, self-esteem, fairness, and the mother-child relationship

This study investigated the effects of the maternal discipline techniques of autonomy support, acknowledgment of negative feelings, reasoning, and firm control on children's and mothers' ratings of various child outcomes. Forty-eight 7-10 year old children, and their mothers, rated a child's self-esteem, present and future compliance, internalization, discipline fairness views, and mother-child relationship, in response to auditory vignettes. Children rated autonomy support as leading to the highest self-esteem (i.e. social worth and empowerment), short-term compliance, discipline fairness, and positive mother-child relationship. Internalization ratings were similar for autonomy support, acknowledgment of negative emotions, and reasoning. Mothers rated the acknowledgment of children's adverse feelings as highly as autonomy support with respect to positive effects on social worth, discipline fairness, and the mother-child relationship. Mothers also rated reasoning as leading to child compliance due to guilt, whereas children reported reasoning as leading to compliance due to fear of adverse repercussions. No differential disciplinary effects existed with respect to future compliance ratings, although explanations for future compliance and non-compliance were examined, and differed according to respondent and discipline technique presented. Children claimed future compliance would be due to fear following reasoning and the acknowledgment of feelings, whereas mothers said guilt and the child's feelings being acknowledged, respectively.
DEA based analysis of corporate failure

The increasing number of corporate bankruptcies in the 1990s have reemphasized the need for research in the area of identifying early warning indicators of corporate distress. The traditional methods used for this purpose have a number of known shortcomings associated with them and there is a continuing need to explore other methods of analyzing financial data. The multidimensional nature of corporate performance makes it a very attractive application area for Data Envelopment Analysis. The goal of this work was to validate the hypothesis that DEA can be used as a tool for predicting future corporate distress. DEA models were used to predict the financial viability of firms based on their historical financial data. The DEA results compared very favorably to those of the popular "Z score" model, and in most cases, the model accurately picked out companies which showed signs of distress as early as 3 years prior to failure.
The stability of friendships for students with and without learning disabilities

The purpose of this study was to investigate the friendship stability of children with and without learning disabilities (LD). The participants were 110 children (52 boys, 58 girls) in grades 4 through 6. Participants and their classmates nominated their best friends and answered various questions about their friends in a structured friendship interview administered in January/February (Time 1) and May/June (Time 2) of the same schoolyear. Parents, teachers and nominated school friends were given an adapted version of this interview. Friendship nominations of children with LD were less stable than those of children without LD. However, children with and without LD did not differ in the stability of those friendships that were corroborated by parents and/or teachers. The self-reported quality of best friendships did not differ between children with and without LD. No significant differences were found between children with and without LD with regard to self-reported friendship duration. The best predictors of friendship stability were LD status, friendship duration and children's reports that their relationship with their best friend was characterized by help and guidance. Self-reported companionship and recreation and conflict and betrayal were less potent predictors of friendship stability for children with LD than children without LD, whereas self-reported intimate disclosure and friendship duration contributed more to friendship stability for children with LD than children without LD.
Gonadal steroid regulation of connexin expression in the rat brain

Intercellular gap junctions are formed by specialized proteins, termed connexins (Cxs). In addition to effects on neuronal electrical excitability, gonadal hormones have been implicated in the modulation of connexins in the brain. The objective of this thesis was to document the expression patterns of two principal connexins in the brain, Cx43 and Cx32, in cycling female rats, castrate or hormone-treated adult female and male rats, and in neonatal rats. Androgen and/or estrogen exposure do not induce large-scale changes in brain connexin mRNA expression. In situ hybridization demonstrates that estradiol up-regulates Cx43 expression only slightly in a few, restricted regions of the brain, including the bed nucleus of the stria terminalis, the dorso-lateral septum, and the periventricular hypothalamus. A possible explanation for the restricted nature of the few significant connexin responses observed is that effects of gonadal steroids may be dependent on coincident or sequential electrical activation of the pathways involved.
A randomized trial of the Ischemic Heart Disease Shared Decision Making Program, an evaluation of a decision aid

This randomized trial evaluated the Ischemic Heart Disease Shared Decision Making Program (IHID SDP). The purpose was to determine if the IHD SDP, when compared to usual practice, improved patients' decision making. One hundred and eighty patients completed the study. The SDP group had a mean satisfaction with decision making process score of 72% compared to a mean of 70% for the control group (p = 0.5). The SDP group had a mean knowledge score of 76% compared to a mean of 62% for the control group (p $<$ 0.005) and chose to pursue revascularization 59% of the time whereas 76% of the control group chose revascularization (p = 0.02). We conclude that the IHD SDP, when compared to usual practice, did not increase patients' satisfaction but increased patient knowledge and may decrease revascularization.
A retrospective review and analysis of the need for a hospital-based dental care program for the adult with disabilities

The primary objective of this investigation was to generate a medical and dental profile of the 1384 patients currently attending the Mount Sinai Hospital Dental Program for Persons with Disabilities, to determine which patients require dental care in that setting. The secondary objective was to determine the patient's perception on their need for treatment in a hospital-based dental clinic by means of a questionnaire sent out to 706 of the patients. Results indicate that the profile of a patient who is likely to require treatment in a hospital-based dental program is primarily associated with the presence of moderate to profound mental retardation (39.5%) and/or moderate to severe behavioural problems (31.1%). The patients who perceived the need for hospital-based dental care and actually appear to require this service can be identified by overall poor behaviour (86.7%) and relative non-cooperation at other medical visits (52.3%). Mental retardation and behaviour problems are the predominant determinants of a person's character profile which may be used to readily screen for patients who require care in a hospital-based dental program. These criteria can be utilized to select patients who qualify for care in a hospital-based dental clinic as well as to refer patients who do not meet the criteria to appropriate community-based dental facilities.
The influence of fly ash and early-age curing temperature on the durability and strength of high performance concrete

Early-stage curing temperature has a significant effect on high performance concrete durability and strength. Concrete cures at high temperatures when poured in large volumes due to the autogeneous heat generated by the hydration reactions of cementitious materials. The addition of supplementary cementing materials to concrete reduces the heat of hydration and extends the service life in structures by improving both long term durability and strength. This thesis investigates the effects of early-age curing temperature on the durability and strength of silica fume and fly ash modified concretes. Accelerated test methods were used to measure chloride diffusion in concretes produced with silica fume cement (T10SF) and various levels and types of fly ash replacement. The concrete mix determined to be the most durable with respect to chloride diffusion had 56% of the Type 10SF cement replaced with a moderate-level calcium content fly ash. The use of the Rapid Chloride Permeability Test, (ASTM C 1202, AASHTO T 277) has been widely criticised. Despite a limited data set, good correlation was shown in the results of this research between a two-chamber accelerated chloride migration cell test, and the RCPT.
Refurbishing alamethicin, a path to anion selectivity

Cystic Fibrosis Is a disease caused by a reduced number of chloride channels (called CFTR). By replacing these complex proteins with a simple anion-selective channel, the effects of the disease may be reduced. The voltage-gated peptide alamethicin serves as a model for such a treatment, although it is cation-selective and forms channels with a variety of conductance levels. This thesis outlines routes towards the conversion of alamethicin from cation- to anion-selective through the strategic incorporation of positive charge. Charge concentration within the channel mouth, as in Alamethicin-Dimethylethylenediamine, as well as surrounding the channel, as in the case of Alamethicin-N,N$\sp\prime(3,3\sp \prime$-dipiperizylpropyl)dimethyl malondiamide is explored. Additionally, the stabilisation of alamethicin channel formation is tackled through the linkage of peptide monomers. Bis(N-3-aminopropyl)-1,7-heptanediamide attaches two peptides at their C-termini, reducing the number of preferred channel sizes; $\alpha$-cyclodextrin has the potential to link six monomers, thereby creating a fully stabilised hexameric channel. A combined use of these approaches may lead to a useful anion-selective synthetic channel.
Molecular and environmental aspects of latex film formation

This thesis examines mainly the formation mechanism and structure of latex films. We investigated the drying behavior of latex dispersions by monitoring simultaneously the loss of water mass and the contraction of the wet dispersion area. A soft latex dries slower than a hard latex, and their blends dry even more slowly. The presence of hydrophilic material facilitates drying. We propose a drying model to explain the results. We examined our strategy for zero VOC (volatile organic compound) coatings, by blending latex particles of a low Tg polymer (e.g., poly(butyl methacrylate-co-butyl acrylate)) and of a high Tg polymer (e.g., poly(methyl methacrylate)). Transparent films can be obtained from blend dispersions when the volume fraction of soft polymer exceeds a critical value $(\Phi \sb{\rm C)}$ ca. 0.5, and when the hard spheres are uniformly distributed in a soft polymer matrix. The hard particles in blends improve significantly the mechanical properties. Interface structure in blend films was characterized by direct non-radiative energy transfer (DET) technique. A finite efficiency of DET, which is proportional to the interfacial area, characterizes a sharp interface between the polymer components, and its slight increase upon annealing the films represents the evolution of interface thickness (up to 7 nm at 140$\sp\circ$C). The DET technique is also employed to analyze polymer diffusion in latex films and to examine the effect of various components on diffusion rate. We find that water has little effect on the diffusion of a hydrophobic polymer (poly(butyl methacrylate), PBMA). For a hydrophilic polymer (a copolymer of BMA with 5 wt% methacrylic acid), the presence of water increases the diffusion coefficient by a factor of 5 in the protonated sample, and by 2 orders of magnitude for the sample neutralized by a base (e.g., NaOH). The BMA oligomers enhance significantly the diffusion rate of high molar-mass PBMA. Finally, we examine strategies for ambient crosslinking of latex films. Films with acetoacetoxy functionality can be crosslinked rapidly with diamine as a crosslinker. Films with unsaturated bonds can be cured with the addition of an organic salt (e.g., cobalt octoate) m several days during which a high degree of polymer interdiffusion can be achieved.
The relations among speed of information processing, intelligence, and strategy use

This thesis examines the relation between IQ and inspection time (IT; the minimum time required to reliably identify a highly evident feature of a stimulus) among university students. Experiment 1 introduces a same/different letter discrimination task conducted with the IT procedure. The letter IT task was found to successfully eliminate the use of systematic strategies, such as apparent movement and flash cues; in the past, such strategies have made the IT-IQ correlation difficult to interpret. Results of Experiment 2 indicate that when tested over five consecutive days, the letter IT task is as reliable as the typical 2-line procedure. Experiments 3 and 4 begin examining the extent to which higher order cognitive processes affect performance on the letter IT task. Results of these experiments further support the view that cognitive factors such as attention continue to be at least partly responsible for IT performance, suggesting that the IT task is more cognitively complex than previously believed.
The effect of natural fencerows on local standardized windspeed, temperature and relative humidity

The effect of natural fencerows on the local microclimate was studied at two different sites at Lunenberg in 1995 and at Metcalfe (Eastern Ontario) 1996. Windspeed, air temperature and relative humidity were measured at six stations perpendicular to the fencerow. Data for each of the five stations closest to the fencerows were standardized relative to the station farthest downwind (beyond a significant influence of the fencerow). The porosity of the fencerows, an important factor in determining the efficiency, was determined by using photographs and GIS soft ware program. Standardized windspeed and relative humidity did not differ significantly with distance from the fencerow at the Lunenberg site. At Metcalfe standardized windspeed, temperature relative humidity were significantly affected by the variation in distances from the natural fencerows. Porosity at the two fencerows was similar, 30 and 33% at Lunenberg and Metcalfe respectively, but the coefficient of variation (CV) was higher at Lunenberg, 0.45 vs 0.23, indicating greater heterogeneity.