VictorJuiz/thesis huggingface dataset:
Extrusion processing for manufacture of low-density microcellular polycarbonate foams uing carbon dioxide

This thesis presents the effective strategies for increasing the volume expansion ratio and the cell density of polycarbonate foams. The basic strategies are: (a) to use sufficiently high pressure all through the extrusion system; (b) to use branched material; (c) to use high pressure drop rate at the die exit; (d) to use sufficiently high contents of CO 2; (e) to optimize the processing temperature. The effects of processing and material parameters on foam morphologies were thoroughly studied using a single-screw tandem foam extrusion system. By tailoring the processing and material parameters, polycarbonate foams with an expansion ratio of up to 19 times with a cell density over 1010 cells/cm3 were successfully produced. A continuous extrusion process for the manufacture of low-density microcellular polycarbonate (PC) foams using CO2 is presented. Due to its outstanding mechanical properties and high thermal resistance, polycarbonate foams have been considered as a candidate that will broaden the applications of foams in new industrial areas with high temperature environments.
Development of an optimized strategy for integrated traffic and transit signal control

This dissertation presents an innovative optimized strategy for Integrated TRAffic and TRAnsit signal Control (ITRAC). The development of ITRAC progressed through three phases each offering a stand-alone contribution while offering a foundation for the following phase. Phase one focused on the development of a genetic optimization procedure for traffic signal control without transit signal priority. Phase two focused on the development of an advanced rule-based transit signal priority system that does not optimize timing plans for traffic. It assumes a traffic signal control system running in the background, and provides transit signal priority in a way that reduces negative impacts on traffic. This system is named TSP-Advance and is considered a stand-alone improvement to the state-of-the-art transit signal priority. Phase three expands the study further by developing an optimization based system for integrated traffic and transit control (ITRAC). ITRAC extends the optimization module in phase one to explicitly include transit delay. ITRAC benefits from insights gained in phase two, but actually replaces TSP-Advance with an extended optimization procedure. It is recommended that TSP-Advance would be deployed if a traffic signal control system is already in place. If a complete integrated solution is sought, then ITRAC would be the recommended approach.
Identifying the roles of Rac 1 and Rac 2 in osteoclastogenesis - in vitro

Bone is a unique organ formed of dense, mineralized connective tissue that is formed and regulated by osteoclasts and osteoblasts. The aim of this study was to identify the role of Rac 1 and Rac 2 on osteoclastogenesis. Murine bone marrow cells and peritoneal macrophages, with the targeted deletion of Rac 1 and Rac 2 genes, were cultured in the presence of sRANKL and M-CSF. In vitro osteoclastogenesis, actin pyrene incorporation, spreading, and migration, were investigated. Commensurate with the impaired formation of osteoclasts, actin polymerization was impeded with Rac deletions, as was spreading and migration, while expression of the osteoclast markers TRAP and cathepsin K was delayed. These studies, therefore, demonstrate that the small GTPases Rac 1 and Rac 2, through their effects on cytoskeletal remodelling, are critically involved in M-CSF and RANKL induced osteoclastogenesis. Rac 1 plays a more significant role than Rac 2 in the early phases of osteoclast formation, prior to precursor fusion.
An exploration of the determinants of mortality among hospitalized heart failure patients in Ontario, Canada

In this thesis, we performed studies that serve as a foundation for research in heart failure mortality outcome assessment. Validation studies of the coding of heart failure in the Canadian Institute for Health Information discharge abstract database were performed. Comparison with clinical data sources confirmed the high predictive value of coding of heart failure in the administrative dataset, but undercoding of comorbidities. Using administrative datasets, trends in heart failure outcomes and the association with drug therapies were examined. Although significant changes in drug therapy were observed over time, crude mortality rates after index heart failure admission continued to be high, decreasing by 1.3% from 1992/93 to 1999/00. There was no decrease in 30-day mortality rates during this time. Since mortality remains high, a prognostic model for mortality prediction was developed and validated using clinical databases. Features predictive of mortality included age, presentation vital signs, routine laboratory tests, and comorbid conditions. Heart failure is associated with high rates of mortality and re-hospitalization. Variations in cardiovascular disease outcomes have been demonstrated to occur, and may reflect the quality of care provided. Mortality is fundamental in quality of care assessment because of the importance of process-outcome links and its role as an outcome indicator of quality care. Validation of administrative datasets allow for future studies of heart failure outcomes using clinical data sources. Predictive models for heart failure mortality can be used to adjust for patient risk when evaluating variations in heart failure outcomes, and may be useful for stratification of mortality risk.
An air traffic control display concept for conveying integrated temporal and probabilistic conflict information

An innovative air traffic control display that explicitly incorporates uncertainties in velocity, heading, and position of each airplane is introduced. Probabilistic, temporal, and spatial information about conflicts is provided through integrated graphical patterns. As a part of a proof of concept evaluation, three display conditions were developed: Probabilistic Display consisting of probabilistic and temporal conflict information; Deterministic Display consisting of only temporal information; and Conventional Display without any conflict information. Participants engaged in an air traffic conflict resolution task by issuing commands that were then categorised into "appropriate" and "inappropriate" decisions using a post-hoc analysis tool. Taken together, the numbers of appropriate and inappropriate commands were not affected by the displays; however, when analysed separately, an interesting pattern of decision criteria emerged. Results also showed that mental workload was lower for the Probabilistic and Deterministic compared to the Conventional Display. Finally, subjects strongly preferred the Probabilistic Display over the others.
Critical role of membrane-type 1 matrix metalloproteinase in collagen phagocytosis by fibroblasts

Degradation of collagen is important for the physiological remodelling of connective tissues during growth and development, as well as in wound healing, inflammatory diseases, and cancer cell invasion. In remodelling adult tissues, degradation of collagen occurs primarily through a phagocytic pathway. While various steps in this pathway have been characterized, the enzyme required to initially fragment collagen fibrils for subsequent phagocytosis has not been identified. Using laser confocal microscopy, TEM, and biochemical assays, fibroblasts were shown to initiate degradation of collagen through the collagenolytic activity of the membrane-bound metal lop roteinase, MT1-MMP. Degradation of natural and reconstituted collagen substrates correlated with the expression of MT1-MMP, which was localized at sites of collagen cleavage at the cell surface and also within the cells. In contrast, the gelatinolytic activity of MMP-2 was not required for collagen phagocytosis. These studies demonstrate a pivotal role of catalytically active MT1-MMP in preparing collagen fibrils for phagocytic degradation.
Intimal thickening and hemodynamics of human coronary artery bypass grafts

The long-term success of coronary artery bypass surgery is limited by intimal thickening (IT) along the graft and at the graft/artery junction (distal anastomosis). It is well documented that hemodynamic forces, in particular wall shear stress, are linked to the cellular and molecular processes associated with vascular disease, and these forces have been hypothesized as a cause of bypass graft failure. The objective of this thesis is to gain further insights on the role of wall shear stress in the stenosis of human coronary artery bypass grafts (CABGs). Histologic data, collected from 74 human coronary artery bypass grafts, were used to quantify the intimal response in early (1 week to 2 months in situ) and late (>2 month in situ) saphenous vein (SV) and left internal thoracic artery (LITA) grafts. A visible intimal thickening response at the suture line begins one-week post surgery and became significant by two months. After two months, the greatest thickening occurred on the hood in both types of grafts. Focal thickening on the floor of the distal anastomosis was variable. Quantitative flow visualization analysis of two anatomically correct human CABGs models revealed a large spatial gradient in shear stress on the hood. This gradient was created by the significant curvature of the surgically constructed distal anastomosis. Similar hood geometry was evident in 5 of 6 casts collected. The pattern of wall shear on the floor of the distal anastomosis was unique for each model. The development of hood intimal hyperplasia and the presence of a large spatial gradient in shear stress on the hood suggest shear-induced stenosis may cause bypass graft failure at the distal anastomosis.
The meaning of mental illness to youth: exploring the psychosocial effects of mental illness on identity and life cycle development in youth aged 17-24

This study investigates the subjective experiences of youth aged 17–24 with mental illness and their subsequent social adjustment problems due to the social stigma associated with mental illness and how they become alienated by the symptoms of the illness. Current understanding of the mental health problems of this age group is limited. The developmental tasks of late adolescence and early adulthood appear to be connected to youth's experiences of mental illness, in that the milestones of independence, establishing a young adult identity, sexuality, and career contribute to the effect of, and responses to, mental illness. Youth were recruited from and interviewed at a community-based youth-centred mental health program situated in the city of Toronto, Canada. Through a qualitative analysis, an understanding of youth and their processes of becoming mentally ill emerged. The results showed that youth with a mental illness felt stigmatized and labelled, and experienced multiple losses of identity, family, career choices, and educational and social standing. Four categories emerged as stages that described the participants' process of becoming mental ill: emergence, loss, adaptation and recovery. Participants' reported that mental illness disrupted their lives on every level, especially the interruption in the transition from adolescence to young adulthood. Participants described this interruption in the context of experiencing difficulty with identity, social and maturational development due to both the biological and the social effects of marginalization and stigma associated with their illnesses. However, data also revealed how youth adapt and recover. The implications of the findings in this study may be useful in anticipating and identifying interventions that are more specific for youth with mental illness, whether formal or informal, program-centred or system-focused, and may perhaps assist in developing policy tailored specifically for such youth. Finally, the themes identified through this study can serve as a base for developing and testing further research.

Keywords: Mental illness, Public opinion
Youth, Mental health
Stigma (Social psychology)
Personality
Deviant behavior, Labeling theory
People with mental disabilities, Psychology
The role of Shh, Gli and Irx genes during mouse neural patterning

The patterning of the mouse neural tube is a complex mechanism involving several patterning genes. The embryonic expression of Irx genes in the developing nervous system suggests they play an important role in the dorso-ventral patterning of the neural tube in response to Shh, as well as in the patterning of other organs in mouse. Gene targeting was used to determine the role of Irx2 and Irx5 genes during the mouse development. My studies showed that the dorso-ventral patterning of the neural tube as well as the development of the midbrain-hindbrain boundary appeared normal in Irx2-/- and Irx5 -/- mutant mice. Irx2-/-;Irx5 -/- mutant mice display stronger phenotype than Irx2-/- and Irx5-/- single mutant mice, which suggests that that these two genes are partially redundant in mouse. However, their function appears to overlap mostly during late embryogenesis, as Irx2-/-;Irx5-/- mutant embryos do not display neural patterning defects. In contrast, work done in collaboration showed that Irx5-/- mutant mice display defects in heart and neural retina development. Shh morphogen was thought to regulate the expression of Irx genes, as well as other patterning genes, along the dorso-ventral axis of the neural tube. Although Shh is known to control the patterning of the entire neural tube, the mechanism used by Gli2 and Gli3 to mediate Shh signal in the hindbrain have not been studied. My work examined the hindbrain patterning in Gli2- and Gli3-deficient mice and strongly suggests that Gli2 and Gli3 play a distinct role in the hindbrain than in the spinal cord. More precisely, Gli2 and Gli3 play a rhombomere-specific role in the dorso-ventral patterning of the hindbrain. This strongly suggests that Shh signal is mediated by different mechanisms at distinct rostro-caudal levels of the neural tube.
Identity construction of Black Canadian youth in multicultural settings

The question of what does it mean to be black in Canada has been approached from many different perspectives. In this thesis, I explore several different narratives of blackness in light of narratives of authenticity for black youth, narratives of acceptable blackness, and nation-building discourses in the institutions of media and education. I interview four youth who have participated in race-based cultural groups. I contend that these groups offer particular narratives of blackness that resist the limits placed on black identities by current stereotypes that are continually referenced in popular culture and nation-building discourses. Using an antiracist framework informed by critical race studies and diasporic perspectives of identity, I examine the ways in which the discourses the respondents access in the interviews challenge, confirm or resist the nation-building discourses within media and education and the stereotypes of blackness circulated via popular culture.
Communication over an acoustic channel using data hiding techniques

This work proposes a communication system for imperceptible transmission of data over an acoustic channel. The proposed algorithm can be used to embed data into the ambient sounds of an environment. Although of a low rate, a clear benefit of such a system is that the transmitter is a speaker, and the receiver is a microphone, both of which are already present in numerous devices such as computers and cell phones. To accomplish this task, two new data hiding techniques based on the spectral and temporal acoustic properties of the host ambient sounds, are developed. The highest data rate achieved was 213 bits/s, while keeping the error rate under 10%. The more successful technique was applied in a simple navigation example, where acoustic data embedded in music indicates the position of the receiver.
Extracellular matrix remodeling: potential mechanisms by which aldosterone blockade improves ventricular remodeling and function post myocardial infarction

Aldosterone may contribute to heart failure and myocardial infarction (MI). Post-infarction and heart failure trial (EPHESUS) demonstrated a dramatic reduction in mortality and hospitalization for patients randomized to eplerenone (selective aldosterone antagonist). We explored the mechanism of aldosterone post-MI in a rat model. Sprague Dawley rats (N = 100) underwent LAD ligation or sham and then randomized to sham with vehicle, MI with Vehicle, and MI with eplerenone in rat chow. At day 35 post-MI, animals on eplerenone treatment had improved heart morphology and ventricular function evidenced by improved LV systolic pressure, contractility, relaxation, and compliance. Eplerenone treatment decreased collagen fraction in the contralateral viable zone, as mirrored by MMP2/TIMP2 ratios. Microarray analysis in the infarct region revealed down-regulation of MMP12 and MMP14, and up-regulation of Collagen type II alpha 1, confirmed by traditional molecular techniques. We propose a novel mechanism whereby aldosterone contributes to adverse infarct remodeling and heart failure through matrix modulation and collagen alterations. Aldosterone antagonists may have important therapeutic potential following myocardial infarction.
Precautionary measures: race and the politics of "sex education" in black women's lives

Black mothers are largely thought to communicate information about sex and sexuality in cryptic and proverbial ways. This includes stern warnings to their daughters about personal ruin and compromised morality should they come into sexual contact with a man. Cautious messages such as, 'don't let a boy touch you' is the extent of sex education for many daughters. Explanations regarding our mothers' reluctance to present straightforward information about sex and sexuality include strict religious upbringing; embarrassment; lack of knowledge; or the belief that the school will teach us what we need to know. While these are valid explanations, I propose that cryptic messages are also connected to our mothers desire to socialize daughters into educated and independent women. Our mothers' mantra is: "keep your legs closed and your head in the books. Once you have a career the man and the children will follow!" This qualitative study with fourteen African Canadian mothers and daughters aims to determine how discourses about 'sex education' are produced and how they ought to be understood. It pursues these goals by examining the dynamics and complexities of the mother-daughter relationship using grounded theory and a Black feminist analysis. The data collected revealed that while mothers do talk to their daughters about sex, these conversations are largely shaped by the desire that their daughters should have more choices for a better quality life. This is particularly so for mothers who know the sting of gendered racism in the labour market. The research proposes a more complex look at Black mothers' role in socializing their daughters for success under oppressive social and economic conditions.

Keywords: Women, Black, Canada
Sex instruction
Mothers and daughters
Racism, C6anada
Caspase inhibitor BAF selectively rescues new neurons in the adult rat hippocampus

The hippocampus is a remarkable structure that produces new neurons in its dentate gyros subregion throughout life. This process is countered by a parallel removal of extraneous and old neurons through apoptotic cell death. Most adult generated neuronal progenitors are lost during a critical period one-week after their production. The current study investigated the effects of broad-spectrum caspase inhibition at this time on survival of new neurons in the adult DG. Rats were injected with BrdU nine days prior to BAF caspase inhibitor infusions. BAF was delivered in vivo through an implanted cannula over three consecutive days. Immature neuron survival was significantly enhanced by 30% with treatment. Furthermore, this increase was largely localized to medial and ventral suprapyramidal blades of the DG. Apoptosis appeared unchanged by the treatment; however, this is actually an expected outcome. Enhanced neuroblast survival may be beneficial for certain types of learning and memory.
Development of elastin-based biomaterials by PEG conjugation to an elastin polypeptide

A recombinant, human elastin polypeptide (EP20-24-24) has been conjugated to polyethylene glycol (PEG). Two bifunctional PEGs were investigated for covalent attachment to the EP20-24-24 polypeptide: PEG-divinyl sulfone (PEG(VS) 2) and vinyl sulfone-PEG-N-hydroxy succinmide ester (VS-PEG-NHS). PEG conjugation to the elastin polypeptide was conducted by addition of one of the functional end-groups of polyethylene glycol with an amine group on the peptide, of which there are nine. The second functional group remains unreacted as a group for use later in attachment, crosslinking, or functionalisation. Preferential reaction of PEG(VS)2 at the N-terminal amine group was achieved by reacting at pH between 7.0–7.5 for 1 hour in a 25x molar excess of PEG(VS)2. In addition, the extent of PEGylation was controlled by varying pH, reaction time and amount of PEG(VS)2. Verification of degree of PEGylation was obtained using MALDI-TOF spectroscopy as well as standard SDS-PAGE followed by immunoblotting.
Climates of collaboration: interdisciplinary science and social identity

Interdisciplinarity is required in many kinds of scientific research, particularly complex, multi-factored, policy-relevant projects. This dissertation describes how knowledge workers might facilitate interdisciplinary science through understanding both disciplines and interdisciplinary working groups as social identities. A case of research on the human dimensions of global climate change is used as an example of “new science”—science that is problem-oriented, policy-relevant, and that requires input from many different knowledge fields. Two characteristics of the case study are noted: (1) scientists are able to cross disciplinary boundaries; (2) scientists from different interdisciplinary groups can have trouble working together. After considering these characteristics using ideas about disciplinary boundaries and boundary-crossing that come from the philosophy and social studies of science, I recast both points using a social psychological theory of intergroup relations. The social identity approach shows that intergroup tensions are created by strong identifications with particular social groups. When both disciplines and interdisciplinary groups are seen as social groups, the social identity perspective provides a new explanation for (a) boundary-crossing between disciplines, and (b) barrier formation between interdisciplinary groups. Social, institutional, theoretical and cultural boundaries can become barriers when researchers feel strongly identified with a group, whether disciplinary or interdisciplinary. Highly discipline-identified researchers, I suggest, will have more difficulty crossing disciplinary boundaries to work on interdisciplinary projects. Similarly, collaborations between researchers who identify strongly with different interdisciplinary groups can be difficult, even though research in both groups is interdisciplinary. I suggest that researchers can facilitate a desired form of interdisciplinarity by creating a climate that encourages participating scientists to identify strongly as members of the same group. When this kind of group identity is more salient that competing disciplinary and interdisciplinary identities, researchers are less likely to perceive theoretical, social and cultural boundaries as barriers.