VictorJuiz/thesis huggingface dataset:
Laboratory studies of the gas-surface interactions of hydrocarbon soot in the atmosphere

The physical chemistry occurring on hydrocarbon soot was studied in order to better gauge the reactivity and gas-surface partitioning of fresh and aged soot in the atmosphere. This was achieved by studying the reactive and non-reactive uptake of several atmospherically relevant organic and inorganic chemicals covering a wide range of physical and chemical properties in a coated wall flow-tube coupled to a mass spectrometer. The elemental composition of the soot surface was similar for all soot substrates and was found to be on average 96.3% carbon, 6.1% oxygen and 0.3% nitrogen. The percentage of organic carbon ranged from 6 to 16%. The BET specific surface area for the samples was determined. The uptake of gas phase HNO3 was measured on fresh soot as a function of temperature, partial pressure, relative humidity and oxidation state of the soot surface. The uptakes were reversible and well modeled by the dissociative Langmuir isotherm and the Langmuir-Freundlich isotherm. Physical scavenging of HNO3 by soot aerosols will likely not be an important loss mechanism. The uptake of a series of aromatic hydrocarbons was measured on soot as a function of temperature, partial pressure, relative humidity and presence of a co-adsorbed surface species. The uptake isotherms were indicative of reversible adsorptive partitioning and were well modeled by the Langmuir isotherm. The competitive Langmuir isotherm was unable to quantitatively describe the uptakes when there was a considerable difference in the adsorption enthalpies between the two adsorbing gases. A parameter linear free energy relationship was developed between the partition coefficient for adsorption and the compound's (sub-cooled) liquid vapor pressure. The uptake of NO2 on soot was measured as a function of partial pressure, temperature, surface oxidation state and co-adsorbed surface species. The uptake generated HONO with a 96 +/- 18% yield, was non-catalytic, and is consistent with a mechanism where the surface is reducing NO2 . Although evidence suggests that the heterogeneous reduction of NO2 on soot cannot alone account for the nighttime build up of HONO in polluted environments, the same mechanism occurring on other surfaces may be significant.
Characterization of PDGF-B and TRIM47, two target genes downstream of TNF and NF-kappaB

The role of TRIM47 in cell survival signaling is less clear, but initial characterization suggests that TRIM47 may feedback to regulate the NF-kappaB signal and/or crosstalk with the p53 signaling pathway. TRIM47 also appears to be a potential E3 ubiquitin ligase and may modulate NF-kappaB and p53 signals through ubiquitination. TRIM47 also appears to affect NEMO/IKKgamma levels, and physically interact with p53. TNF is a pro-inflammatory cytokine capable of inducing both death and survival signals. The survival pathway is primarily mediated by a genetic program activated by the transcription factor NF-kappaB. Deregulation of TNF and NF-kappaB signals have been implicated in oncogenesis, and may contribute to the relationship between chronic inflammation and cancer. Platelet derived growth factor B (PDGF-B) and TRIM47, also known as "gene overexpressed in astrocytoma," were identified by microarray screening as tumour necrosis factor (TNF) inducible genes that are dependent on NF-kappaB. PDGF-B, a known growth factor and oncogene, was found to protect NF-kappaB-deficient cells from TNF induced cell death by autocrine/paracrine signaling through the PDGF receptor. Wild type cells were sensitized to TNF induced cell death with PDGFR inhibition, and this correlated with sustained MAPK signaling and elevated reactive oxygen species levels. PDGF-B transformed cells were significantly more susceptible to TNF killing than wild type cells with PDGFR inhibition, suggesting that these malignant cells are highly dependent on PDGF-B signals to evade death receptor-induced apoptosis. Both PDGF-B and TRIM47 suggest that NF-kappaB target genes downstream of TNF may promote cell survival in ways that do not depend on directly opposing TNF cell death machinery. Crosstalk with other pathways---by induction of a cytokine cascade or by influencing other survival and apoptotic signals---likely integrate various signals downstream of TNFR1 to help determine cell fate in response to TNF.
The effects of contact guidance and electrical field stimulation on the maturation of cardiac progenitors and cardiomyocytes

Cardiac tissue engineering requires an appropriate cell source. We investigated the feasibility of various immature cardiac cells, namely neonatal heart cells and embryonic stem cell derived cardiomyocytes and progenitors, in their ability to create the desired adult cardiomyocyte (CM) phenotype. We found that the application of contact guidance and electrical field stimulation improved the alignment and elongation of neonatal cells within a monolayer cultured polyvinyl carbonate or tissue culture polystyrene, as well as the contractile function of the culture. These cells were found to express mature cardiac cell markers such as Troponin I and alpha-sacromeric actinin, in addition to forming gap junctions with neighbouring cells. A similar approach, applied to human embryonic stem cells derived-cardiomyocytes (hESC-CM), shows some promise in maturing these cells into the adult cardiomyocyte phenotype. Finally, we also explored various methods for isolating isl14+ cardiac progenitors from the neonatal rat heart.
The deterrent effects of cigarette taxation policy on smoking

There has been much research into how cigarette taxation affects cigarette use in various demographic groups, but little work into its effect on daily and non-daily user groups and within these user groups. Also, none of the existing studies assesses the extent to which alcohol use influences the deterrent effects of cigarette taxation policy. The present research used innovative quantile regression techniques on individual-level Canadian data: (1) to estimate separately the impact of cigarette prices on various levels of smoking among daily and non-daily smokers, and (2) to explore how frequency of alcohol consumption affects cigarette price sensitivity among daily and non-daily smokers at various levels of smoking.

Keywords: Economics
Public health
Modulation of insulin signalling molecules and hepatic lipoprotein production

Insulin is known to decrease apolipoprotein B (apoB) secretion in various hepatic models, an observation that is thought to be mediated through the phosphatidylinositol 3-kinase (PI3K) pathway. To investigate whether the insulin inhibition on apoB secretion involves molecules downstream of PI3K, we overexpressed a downstream kinase, Akt/PKB. Overexpression of activated Akt did not affect apoB levels as shown by immunoblotting and radiolabelling experiments in hepatic cell lines McArdle RH-7777 or HepG2. To test the involvement of the mitogen-activated protein kinase (MAPK) pathway in the insulin effect, the MAPK kinase, MEK, was inhibited using chemical inhibitors in HepG2 cells. Blocking the MAPK pathway alone decreased cellular and secreted apoB, and the insulin effect was blocked in MEK-inhibited cells. Therefore, the insulin effect on apoB appears to involve molecules upstream of Akt in the PI3K pathway, and apoB may be regulated by the MAPK pathway with a mechanism independent from insulin.
Application of sheep lymphatic dynamics to monitor immune responses in periodontal tissues

There is a wealth of evidence to indicate that tissue destruction in periodontitis is mediated by host defense mechanisms. Since the traffic of lymphocytes is an important component of host defense, a better understanding of the recirculation and homing patterns of lymphocytes to the gingival tissues would contribute to a better understanding of the pathogenesis of periodontal diseases. The study of lymphocyte recirculation and homing can only be done using an animal system. To develop the sheep model for monitoring immune responses in the oral mucosa during the pathogenesis of periodontal diseases, the lymphatic drainage pathways from gingival tissues were determined. Qualitative and quantitative studies were carried out to map these pathways. From the qualitative studies, two major pathways provided drainage for the periodontal tissues: (1) cervical lymph ducts and (2) efferent prescapular lymphatics. To compare the relative importance of these two drainage pathways, radiolabeled proteins were injected directly into the periodontal tissues and their appearance in cervical and prescapular lymph was measured. Over a period of 7.5 hours, approximately 65% of injected proteins were recovered in the prescapular and cervical lymph vessels (32% and 33%, respectively). To test the feasibility of the model system, humoral immune responses and the induction of antibody secreting cells to chicken red blood cells (chRBC) as a model antigen injected into the periodontal tissues were examined in draining lymph. Characteristic changes associated with the inflammatory response were detected and monitored continuously in the draining lymph. I next investigated whether tissue-selective migration directs specific lymphocyte subsets into inflamed gingiva. When T cells were labeled with radioisotopes and their migration from blood to lymph was measured, the periodontal tissue traffic pattern was distinct from the traffic patterns in inflamed skin or bowel lesions. This tissue specificity was not apparent when lesions were induced with TNF?. Overall, I have provided detailed morphological and functional analysis of the lymphatic drainage pathways of the gingival tissue in sheep as well as some basic data on the migration of lymphocytes in these tissues. These studies may provide a framework for further investigations of immune processes that occur in experimental periodontal diseases using the sheep model.
Variation in emergency department triage of acute myocardial infarction patients, the effect on outcomes, and predictors of low triage

Conclusion. Half of AMI patients are given a low ED triage score, which is associated with substantial delay to thrombolysis. Background. Emergency department (ED) triage of patients with acute myocardial infarction (AMI) has not been examined. Results. The rate of low triage was 50.3%. Low triage was associated with significantly longer median door-to-ECG and door-to-needle times (by 4 and 15 minutes, respectively). Mortality was not associated with triage. Several variables were independent predictors of low triage. Methods. The EFFECT database contains population-based chart review data on AMI patients in Ontario from 1999 to 2001. We utilized EFFECT data to determine the rate of low triage, defined as a score of III, IV, or V on the Canadian Triage and Acuity Scale, among 3088 patients. Multivariable modeling was used to determine the association between low triage and door-to-ECG time, door-to-needle time, and 30-day mortality, and to assess predictors of low triage.
The formation of organic iodides from the radiolytic decomposition of paint solvents

All the organic iodides formed were identified as iodo-alkanes. The organic compounds that were released by the Ripolin paint were found to decompose, by a series of radiolytic reactions, to produce the organic iodides. The addition of aromatics lead to the delayed formation of the organic iodides. This research examines organic iodide formation, in the containment, due to the release of organic compounds from Ripolin paint, into the aqueous phase, following a nuclear reactor accident. Experiments were carried out in the irradiation chamber of a Co-60 Gammacell, and the organic compounds detected above the irradiated aqueous samples were analyzed using a Thermal Desorption method coupled with gas chromatography and mass spectrometry. The results of this research indicate that the rate of release and type of organic solvents play a major role in the behaviour of organic iodides in the atmosphere. This research may lead to recommendations to control the formation of organic iodides, and will assist in developing models describing the formation of organic iodides following reactor accidents.
On treatment outcomes of implant-supported mandibular prostheses in edentulous patients

To date long-term studies on patient- and dentist-mediated treatment outcomes of patients treated with implant-supported mandibular prostheses are sparse in the literature. In this dissertation, we investigated four groups of unmatched edentulous patients treated at different time periods with fixed and overdenture mandibular prostheses and followed for at least ten years. The implant-related outcomes underscore the fact that once osseointegration was established with the Branemark implant, the prognosis for long-term function in the anterior mandible was guaranteed with both prosthetic techniques. The cross sectional evaluation of patient-mediated concerns with conventional prostheses allowed us to establish patient comparability when they received implant treatment. Furthermore evaluation of the oral health-related quality of life indicated that the two prosthetic designs equally addressed the patients' needs. The prosthodontic outcomes in this study showed that maintenance was related to the prosthesis design and that longevity was in excess of a decade with both designs. Overall the maintenance visits required over the observation period was fairly similar for both prosthetic designs. The economic evaluation of the treatment outcomes clearly indicated that the overdenture approach, at least with a resilient bar retention mechanism, was indeed a more cost effective approach to rehabilitating edentulous patients seeking implant-supported mandibular prostheses. In addition short-term results on immediate loading with overdentures indicated that although from a biological and patient-mediated standpoint the protocol was successful, the clinical and economic evaluation suggested that the particular prosthetic protocol selected was not cost effective when compared to the conventional approach.
The genetic and behavioural analysis of olfactory learning and memory in caenorhabditis elegans

The standard wild type laboratory (N2) strain of Caenorhabditis elegans demonstrates adaptation of its response to benzaldehyde after prolonged exposure to the odorant in the absence of food. Using behavioural analyses we have demonstrated that benzaldehyde adaptation possesses properties of associative learning. Specifically, the worms are learning the association between benzaldehyde and a nutrient deficient environment. Additionally, this process is primarily mediated by serotonergic signalling. The CB4856 strain, another wild type isolate, displays a dramatic deficit in benzaldehyde adaptation. Genetic analysis of this behaviour has revealed that it is a dominant trait. Behavioural analyses have demonstrated that this deficit is specific to benzaldehyde and is not the result of a differential sensitivity to the odorant. In fact, it appears as though the CB4856 deficit is not a learning deficit but a retrieval deficit specific to the benzaldehyde cue.
The role of oligodendroglial cells in the CNS radiation response

The central nervous system (CNS) is a major dose limiting organ in clinical radiotherapy due to the potential for damage to normal tissue. Oligodendrocytes (OL) and oligodendrocyte progenitor cells (OPC) are believed to play a role in the radiation response of the CNS. This study examined the role of early changes in these cell populations with late demyelination. OPC underwent apoptosis within 24 hours of irradiation. Myelin gene expression was reduced by 4â€“5 weeks after both 8 and 22 Gy. Since many of the changes were observed with doses of both 8 and 22 Gy, these early changes are not likely related to late demyelination. Preliminary results have demonstrated that apoptosis of OL or endothelial cells is not the trigger for the early proliferation response. Future work will involve assessing OPC density changes following irradiation and examining the role of OL apoptosis on the development of late necrosis.
Genetic mapping of cobalamin C deficiency linkage to chromosome 1p32-34

Cobalamin C deficiency (cblC) is an autosomal recessive disease (OMIM 277400) with onset in infancy. It is the most common intracellular cobalamin processing disorder, leading to both methylmalonic aciduria and homocystinuria. The molecular genetic defect of the disease is unknown. A genome scan with 306 markers positioned at approximately 10 cM intervals was completed with eleven families with twelve patients. Two-point linkage analysis produced positive lod scores at 1p32–34. Multipoint linkage analysis supported this analysis, yielding a lod score of 7.2 over a 3.2 cM interval. Further analysis of disease chromosomes pointed to a critical region of 3.1 cM (6.1 Mb). The exclusion of the remainder of the genome by multipoint analysis and the linkage findings indicate that there is a single locus for cblC deficiency. With additional families, the current interval may be further refined to lead to the identification of the altered gene.
Growth and nutritional responses of Sesbania sesban (L.) Merr. to rock phosphate, biofertilizer and rhizobial applications

Continuous crop cultivation without adequate fertilizer input has led to poor yields and soil degradation in the tropics. To restore soil fertility through agroforestry practices, N2-fixing tree fallows are planted to produce nutrient-rich biomass that is incorporated in soils. The quantity and quality of biomass produced can be improved by phosphorus fertilization, inoculation with rhizobia or use of biofertilizers. My study examined the effects of rhizobial inoculation, biofertilizer and rock phosphate applications and their interactions on growth and nutrition of S. sesban planted in potted acidic soils of western Kenya. Rhizobial inoculation improved nodulation only when rock phosphate was added. Although biofertilizer failed to stimulate root nodulation, it enhanced plant nutrient absorption. Fertilization with rock phosphate enhanced growth and nutrition of S. sesban most and is recommended for use in agroforestry. There was a small but significant beneficial interaction between rock phosphate and biofertilizer use on Sesbania growth and nutrition.
The contemporary dynamics of Sino-Indian relations: Examining maritime security, economics, energy and elite dialogue

This dissertation examines the modern-day dynamics of the Sino-Indian relationship---with a particular focus on issues relating to maritime security, economics, energy and elite bilateral dialogue. In exploring the contemporary nature of the Sino-Indian relationship, the dissertation also seeks to assess the accuracy of predominant neorealist accounts of the Sino-Indian relationship. Since the 1962 Sino-Indian War, most analysts have continued to emphasize the conflictual and competitive elements within the Sino-Indian relationship. The dissertation first explores the crucial post-independence history of Sino-Indian relations to provide the appropriate contextual background (chapter one). Thereafter, the dissertation explores the geopolitical significance of the Indian Ocean in light of soaring (global) energy demands. This then leads into an analysis of China and India's naval modernization and China's strategic partnership with Pakistan and Myanmar (chapter two). While acknowledging the credibility of neorealist insights in the realm of maritime security by detailing China and India's naval buildup and naval strategy, overall, it is found that the security dilemma argument is overstated. There is both a lack of threat perception and the existence of alternate explanations for both Chinese and Indian activities in Southern Asia. The dissertation then moves on to explore the positive elements within the Sino-Indian relationship---growing economic interdependence, energy convergence and elite consensus. In the economic realm (chapter three) it is found that Sino-Indian bilateral trade is increasingly being framed institutionally and rapidly expanding every year. The areas where the Sino-Indian economic relationship could be fruitfully expanded are traced and the great potential of bilateral trade is discussed. Thereafter, the dissertation highlights how China and India are beginning to coordinate energy policy (chapter four) as well as the growing political will (chapter five) to transform the Sino-Indian relationship from a framework of conflict and competition to cooperation. The dissertation concludes that there are serious mitigating factors in the Sino-Indian relationship and that an exclusively neorealist outlook is impoverished. Theoretical insights from neoliberal institutionalism and constructivism point to how emerging economic interdependence in tandem with the (elite) creation of dependable expectations of peaceful change point towards stability in the Sino-Indian relationship.
The E3 ubiquitin ligase Cbl-b is essential for the induction of in vivo T-cell anergy

Autoimmune diseases are debilitating conditions that pose a significant burden worldwide. T-cells are thought to play important roles in the coordination and development of immune responses in both health and disease. A key checkpoint in the prevention of inappropriate activation of T-cells is the requirement for co-stimulation by professional APCs via receptors such as CD28. The requirement for CD28 engagement for complete activation of T-cells is lost in Cbl-b mutants, which also develop multi-organ autoimmunity and are highly-susceptible to experimental autoimmune conditions, suggesting Cbl-b may therefore play a role in the generation or maintenance of peripheral T-cell tolerance. By subjecting Cbl-b mutant mice to well-characterized in vivo tolerization protocols, we find that T-cells from these mice, unlike those from wild type mice, maintain and intensify subsequent responsiveness both in vivo and in vitro, resulting in lethality. Thus, Cbl-b is indeed essential for the induction of immunotolerance to specific antigens.