VictorJuiz/thesis huggingface dataset:
TCR-mediated signaling in thymocyte selection

TCR-mediated signals have been shown to induce both positive and negative selection of thymocytes. How the same TCR can induce both forms of selection introduces a conceptual paradox. A generally accepted model of thymocyte selection is the "strength of signal" or "affinity/avidity" hypothesis. This model predicts that the absence of any signal from the TCR results in death by neglect, a "strong" signal results in negative selection and a "weak" signal results in positive selection. My thesis examines how these TCR-peptide/MHC interactions are translated into intracellular signals that discriminate between positive and negative selection. The thesis investigates the relationship between the extent of TCR internalization in response to various peptide/MHC stimuli and thymocyte selection outcomes. Our results demonstrate a direct correlation: peptides that induce strong TCR down-regulation are most efficient at mediating negative selection, whereas ligand interactions that induce suboptimal TCR internalization are more efficient at triggering positive selection. These data suggest that T cell selection is mediated by differing intensities of the same TCR-mediated signal, rather than by distinct signals. My thesis also assesses the role of the mitogen-activated protein kinase (MAPK) signaling cascade, specifically the extracellular signal-regulated kinase (ERK) module in regulating both positive and negative selection. We find that negatively selecting conditions induce stronger ERK activation in thymocytes than do positively selecting conditions. We further demonstrate that attenuating the ERK activity by pharmacological inhibition can shift the activation threshold for negative selection to that for positive selection. Moreover, in order to study the kinetics of ERK activation upon stimulation with positive and negative selection stimuli, we devised an 'in vitro ' assay system for thymocyte selection. Data from these studies suggest that weak, sustained ERK activation is characteristic of positive selection, whereas strong but transient ERK activation leads to positive selection. Therefore, both timing and extent of ERK activation appear to be important for thymocyte selection. Since positively selecting stimuli do not induce efficient TCR internalization, the large proportion of TCR complexes that remain on the cell surface may relay continuous signals required for survival and differentiation. Together, these results add a novel viewpoint to thymocyte selection.
Moving against the grain, the expectations and experiences of Tanzanian female undergraduates

Because of the lack of research on women in higher education in Tanzania this study examines women's role in higher education in Tanzania. It is a shift from other studies on women's participation in higher education in Tanzania because it focuses on those who are less understood--the few girls who, despite all the odds against them, have persistently shown an interest in mathematics and the natural sciences and decided to pursue higher education in programs such as agriculture, engineering and medicine. My study is an attempt to take women's crucial role in higher education more seriously and to answer important questions: What type of education do Tanzanian women want? Do Tanzanian women want an education that limits their career choices to unskilled labor market? Or, do they want an education that enables them to participate in higher levels of leadership and professional positions? Women's uneven enrolment in scientific and technological programs raises many other questions: What are some of the policy or institutional-based factors that may explain women's low and uneven participation in university undergraduate programs? This implies going beyond the commonly held view in Tanzania that women's low participation in mathematics and science-based university undergraduate programs is due to girls' lack of interest and poor performance in these subjects at the secondary school level. This calls for an examination of women's participation in specific university programs in order to tease out factors which contribute to gender imbalance specific to each discipline. Despite the rhetoric about "encouraging" girls to study Science subjects, many Tanzanians seem to be more comfortable with an image of a Tanzanian girl/woman as a "failure." This could be a possible explanation as to why the study participants, most of whom were the best performers, experienced little or no acknowledgment from those around them. The research participants learn under a very hostile environment, they are despised, their competencies doubted and they are often unfairly judged. I advocate an increased participation in higher education of Tanzanian women from under represented ethnic, regional, religious and socio-economic backgrounds.
Attributions, emotions, and discipline practices in parents of children with and without ADHD, support for Weiner's cognitive-emotions-action model?

Attributions, emotional reactions, and discipline towards children's inattentive-overactive (IO) and oppositional defiant (OD) behaviors were compared in 30 parents of children with Attention Deficit Hyperactivity Disorder (ADHD) and 26 parents of non-behaviorally disordered children. Parents' causal attributions for child misbehaviors as well as their emotional reactions to these behaviors were examined as predictors of parent discipline practices. Parents were also compared on measures of childrearing ideology, role satisfaction, and optimism. In contrast to comparisons, parents of children with ADHD viewed child misbehaviors as less controllable and more internally caused and stable; they felt more frustrated and helpless; and exhibited harsher discipline. Parents of children with ADHD were also more authoritarian and pessimistic. Although parents viewed children as more responsible and blameworthy for OD behaviors, they reacted most negatively to IO behaviors. In addition, rather than being mediated by emotion, parents' discipline practices were guided by their beliefs about child behavior.
Dysregulation of Indian hedgehog - parathyroid hormone related protein signalling in cartilaginous neoplasia

Enchondroma is a benign cartilage-forming tumour of bone that might be caused by dysregulation of growth plate signals. A paracrine feedback loop couples Indian hedgehog (IHH), which stimulates growth plate chondrocyte proliferation, to Parathyroid hormone related protein (PTHrP), which regulates chondrocyte differentiation. Here I show that these two signalling pathways were uncoupled and IHH was dysinhibited in explant cultures of human enchondromas and their malignant counterparts, chondrosarcomas. A heterozygous variant 'Type I PTH'/'PTHrP receptor' ('PTHR1') was discovered in the germline of one patient and as a somatic change in another with enchondromatosis. In this condition, multiple enchondromas may lead to deformity and chondrosarcoma. The variant PTHR1 suppressed Cyclic adenosine monophosphate baseline level in a dominant fashion and abolished Inositol triphosphate accumulation 'in vitro'. Transgenic mice expressing the variant receptor under the regulatory elements of 'Type II' collagen developed enchondromatosis. I show that the transcription factor Gli2 was a positive regulator of Ihh function in the murine growth plate, while Gli3 was a negative regulator. Overexpression of 'Gli2' was found in human enchondromas, and was sufficient to cause enchondromatosis in transgenic mice. A lack of ' Gli3' accelerated another condition of benign chondrocyte neoplasia, synovial chondromatosis. Patched 1 (PTCH1), a Hedghehog receptor, formed a complex with PTHR1, and this complex was required for effective accumulation of PTHR1 second messengers. The variant PTHR1 did not associate with PTCH1, and constitutively activated Hedgehog signalling in a manner that was likely dependent upon suppression of Protein kinase A. Dysregulation of growth plate signals causes certain benign cartilage tumours. Agents that block Hedgehog signalling in particular, might be useful in preventing the deleterious sequelae of enchondromas.
Marginal adaptation and microleakage of Procera AllCeram copings, an in vitro study

This study sought to investigate the marginal adaptation and microleakage of Procera AllCeram copings (PAC) and porcelain-fused-to metal (PFM) copings with zinc phosphate (ZnPO4), glass ionomer (GIC), resin modified glass ionomer (RmGIC) and resin (R) cements. PFM copings exhibited significantly less microleakage than PAC copings. None of the coping margins cemented with ZnPO4, 58% GIC, 48% RmGIC and 65% in the R group demonstrated zero microleakage. A significant difference between PAC (54[mu]) and PFM (29[mu]) mean marginal adaptations was found. Specimens cemented with ZnPO4 cement showed significantly larger marginal gaps (54[mu]) as compared to GIC (40[mu]), RmGIC (37[mu]) and R (37[mu]). 'PFM and PAC copings provided acceptable margins and the use of R cement resulted in the highest percentage of zero microleakage scores'.
The effects of aging on temporal processing in the rat inferior colliculus, responses to frequency-modulated sweeps

Difficulty in understanding speech is a common problem afflicting the elderly. One potential factor is an age-related deterioration in temporal processing speed, expressed as a decreased ability to process dynamic aspects of speech such as the formant transitions. The study used frequency-modulated (FM) sweep stimuli to examine the effects of aging on auditory temporal processing at a subcortical level, specifically in the inferior colliculus (IC). Extracellular single-unit recordings were made from the IC of young and old Long-Evans Hooded rats in response to linear FM sweeps that changed both in speed and direction. There was no significant difference in the preferred speed of FM sweep between the two age groups. In addition, for direction selectivity of FM sweep, most of the cells in both groups were non-direction selective. The results show temporal processing speed is not affected by aging at the level of the IC.
Quantification and analysis of remanufacturing waste streams for improving product design

This thesis explores sources of obstacles to remanufacturing, particularly those imposed by product design. Remanufacturing, or product recycling, addresses the negative environmental impacts from product disposal. Businesses may choose to remanufacture because of influences from ethics and legislation. Effective design to facilitate remanufacturing requires technical knowledge of the design influence on remanufacturing feasibility. Examination of remanufacturers' waste streams yields empirical evidence of four types of obstacles: product-feature damage, process-execution problems, issues outside of the remanufacturing process, and unidentified problems. Additionally, root causes of the obstacles are surmised. A preliminary reference for design for remanufacture, in the form of tables with root causes and obstacles cross-indexed, is presented. A designer can examine their own product for root causes and possible remanufacturing obstacles. For each table entry, the specific product studied and its proportion of waste stream that was affected by the discard reason are available for further reference.
A critical evaluation of ASTM Method C114, Section 19 for the determination of total chloride content of cured cement and concrete

An assessment was made of the accuracy and precision of ASTM Method C 114 for the analysis of chloride in cured cement paste and concrete. Cement pastes with water-to-cement ratios of 0.45, containing known different amounts of chloride ranging from 0.0 to 8.0 percent by weight of dry cement, were prepared using ASTM Type I Ordinary Portland Cement. The samples were allowed to cure in a hydrostat for 7 and 28 days with and without rotation and then were analyzed for total chloride content using ASTM Method C 114. Complete extraction of chloride from the cement specimens was not achieved, showing the inability of the above method to bring all the chlorides into solution for analysis. For some of the samples containing high chloride content, the ASTM method under-reported the true values by as much as 70%.
Intergranular boron segregation and grain boundary character in Alloy 304 austenitic stainless steel

Secondary ion mass spectrometry (SIMS) and orientation imaging microscopy (OIM) were used to study the relationship between boron segregation susceptibility at grain boundaries and grain boundary structure in Alloy 304 austenitic stainless steel containing boron as a trace solute impurity. Boron segregation was detected at grain boundaries in materials heat treated at 1000 and 1100°C and both boron segregation and carbide precipitation were detected at grain boundaries in materials heat treated at 800°C. Coherent &sum;3 twin boundaries displayed high resistance to both boron segregation and carbide precipitation. &sum;1 (low-angle) boundaries displayed some resistance to boron segregation and high resistance to carbide precipitation. &sum;9 boundaries satisfying the Palumbo-Aust criterion displayed some resistance to both boron segregation and carbide precipitation. Other low-&sum; boundaries and general boundaries (&sum; > 29) displayed low resistance to both boron segregation and carbide precipitation.
Values and leadership practices of secondary school principals in the Kingdom of Tonga

The leadership practices of secondary school principals in Tonga are strongly influenced by the culture, traditions, religion and changes experienced by the society. Principals' leadership practices focus mainly on managerial, moral and instructional matters. Values such as respect, loyalty and reciprocity are manifested and adhered to through their leadership practices. In their efforts to address the social issues confronted by their students, principals prefer values categorized by Hodgkinson (1996) as Type II Values focused on Consequences and Consensus. Principals preferred to deal with these social issues among themselves in the local school context and sometimes with help from the community. The value variations that exist between principals and the Ministry of Education account for the principals' reluctance to use ministerial policies and regulations as procedural guides for their administrative practices.
Law and authority in Upper Canada, the Justices of the Peace in the Newcastle District, 1803-1840

In frontier Ontario, the system of criminal justice administration relied heavily on the services of appointed magistrates who were untrained in law. Justices of the Peace performed many duties that would later become the responsibility of professional police and legally-trained officials. Despite the importance of the roles they performed, magistrates been the subject of few detailed studies, and those tend to examine only a particular aspect of their activities. This study explores more generally the functions that magistrates performed in criminal justice administration and the meanings of those roles in the broader social context. Using the court records of the Newcastle District, this dissertation describes and analyzes the activities of the magistrates at the pre-trial stage, in matters over which they had summary jurisdiction, and at the intermediate court of Quarter Sessions. It shows that justices actively carried out their responsibilities, and they did so in ways which demonstrated knowledge about the law and the effects that their actions had on others in their communities. Evidence suggests that magistrates acted to mitigate the effects of the criminal law on those who came into contact with the justice system. This study also sheds light on aspects of the social and political history of Upper Canada. Settlers in frontier Upper Canada were remarkably litigious. Their willingness to use the criminal justice system and the services that magistrates performed within that system suggests a degree of popular legitimacy that some historians have argued was lacking in the upper courts. That the authority of most magistrates was viewed as legitimate might explain why most people did not become so alienated from the regime that they participated in the rebellion in 1837.
The geographical and statistical associations between noxious land use, mortality, and environmental disparity in Salem County, New Jersey

This study explores the geographical patterns and statistical associations between facilities that report to the US EPA Toxic Release Inventory, contaminated sites defined by the New Jersey Department of Environmental Protection, mortality rates, and various socio-economic groups in Salem County, New Jersey. Salem County has a concentration of chemical industries and power utilities, with high pollution levels relative to the State of New Jersey and a history of pollution related health issues. There is a moderate statistical association between mortality rates for persons under 65 and emissions levels, and a stronger association between cancer mortality rates for persons under 65 and emissions levels. The most polluted townships have a higher number of cancer deaths relative to the expected number of cancer deaths for a population of their size, based on the US average. A clear determination regarding the issue of environmental disparity by race and class could not be made.
An empirically derived typology of families of adolescent male sex offenders

The purpose of this study was to develop a typology of family environments of adolescent male sex offenders. Closed clinical records of 80 adolescents male sex offenders, aged 12-19, and their families admitted for assessment and or treatment at a community based program were reviewed for this investigation. Data were collected related to five identified family variables: family structure, family dynamics, sexual environment, family violence and antisociality. Families were rated on each of these variables using a 5 point Likert scale, from highly stable or problem free to highly unstable or problematic. A trained second rater reviewed 25% of the files and good inter rater reliability was established, Cohen's 'K' > .60 for all family variables (Cicchetti & Sparrow, 1881). A cluster analysis revealed five distinct family groups: Extremely Problem, Structurally Unstable, Multi Problem, Health, and Problematic Parenting, Extremely Problematic families were characterized by a severe disruption on all family variables; particularly, sexual environment, family violence, and antisociality. Structurally Unstable families were distinguishable by problematic family structures, with offenders experiencing many residential moves, major separations from parents, or involvement by child protection services. Multi Problem families noted disruptions on all family variables but not as severe as Extremely Problematic families. Families in the Healthy group did not indicate problems relaxed to any of the family variables under investigation. Problematic Parenting families were characterized by poor parenting skills including inconsistency in parenting, lack of supervision, parentification, and negative communication styles within the family. Variables not used in the formation of the family groups were used to validate and add support to the cluster solution. Specific offense and offender characteristics varied across the family groups. The distinctive family groups in this current investigation confirm the heterogeneity of families of adolescent male sex offenders. Not all adolescent male sex offenders come from dysfunctional family systems and the nature of the dysfunction varies across the family groups. Understanding the specific dysfunction within the family may provide a targeted direction for the family component of an overall treatment program for adolescent male sex offenders.
The best part of valor, a study of Plato's treatment of courage in the Laches and the Republic

Beginning from the finding that contemporary liberalism offers little in response to the probing but ultimately flawed critique of traditional courage that feminist political theorists advance, I argue that there exists an urgent need today to reexamine courage. For despite its undeniably dangerous excesses, I show that courage is critical to both the survival and health even of peaceable liberal democracies and that we therefore need to explore both its risks and its rewards. I turn to Plato because he provides a balanced but richly complex treatment of courage. While it is alive and sympathetic to the multidimensional phenomenon of courage as ordinarily understood, i.e., as the virtue that enables one to act well in the face of dangers, Plato's treatment yields the paradoxical thesis that courage is both the cause and the consequence of wisdom. The ' Laches' and the Republic together illuminate what courage is and why courage is needed to understand what it is. Carefully following the development of Socrates' conversation in the 'Laches' with two Athenian generals who disagree with each other and even with themselves about courage, I argue that the generals' confusion stems from their deep-seated hopes about it, namely, that courage be both noble in itself and also good for the courageous individual. Their unwillingness or inability to examine these hopes is evidence, I argue, of a certain cowardice. Socrates' exploration in the 'Republic ' of spiritedness, which he characterizes as the psychological substratum of courage, shows why it takes (an incompletely developed) courage to examine the opinions that underlie its ordinary manifestations. By comparing the courage of the 'Republic''s guardians with that of its future philosophers, I argue that a failure to confront such opinions produces a courage that is confused and hence deficient; genuine courage requires at the very least knowledge of why it is worth possessing and exercising. But however much the refined spiritedness that underlies the guardians' courage falls short of the highest kind of courage, I argue that it still deserves respect as both politically reliable and suited for acquiring the wisdom that is the source of genuine courage.