30921 research outputs found
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Towards an internet of blockchains: decentralized discovery services with layer 2 ceremonies
Get PDFThe rise of heterogeneous blockchain platforms that are utilized by various organizations depending on their needs has created an interoperability problem. While significant progress has been made in enabling interoperability between blockchain networks, most works in this area assume that these networks are already aware of each other. This thesis makes two key contributions to fill this gap. First, it introduces a decentralized architecture for inter-blockchain network and asset discovery that allows domain registration and resolution without dependence on a central authority. The system is self-sufficient, scalable, and enables dynamic discovery across blockchain networks. Second, it presents a decentralized mechanism for generating trust anchors through multi-party cryptography ceremonies. By increasing the number of participants constructing Common Reference Strings (CRS) and periodically regenerating it, the mechanism enhances the security of zero-knowledge systems while maintaining their decentralization. The evaluation of both implementations shows that the discovery architecture achieves high throughput under heavy load and scales efficiently with the number of participants. Similarly, the trust anchor generation mechanism performs resilient CRS generation ceremonies within bounded durations.This work was partially funded by a grant from the Web3 Foundation.February 202
Reducing undergraduate students’ trust of commercial contract cheating websites with an academic support literacy intervention
Get PDFThe acquisition of products and services from the commercial contract cheating industry has an extensive history, with the industry experiencing significant growth during the COVID-19 pandemic. Since then, these commercial entities have added generative artificial intelligence (genAI) to their websites to ensure continued use of their services by postsecondary students. Cheating providers use various other persuasive features (e.g., assurance of quality work, use of the words ‘guarantee’ and ‘secure’) to convince students to trust them and become customers. To counter the efforts of commercial cheating services, education about the cheating industry and academic integrity should reduce any trust that students have in them. We developed an academic support literacy module about appropriate (e.g., university assistance, legitimate tutors) and inappropriate (e.g., contract cheating services) academic support. Before and after the module, 39 introductory psychology students rated how much they trusted various websites using a 12-item consumer trust scale. Although a drop in trust after viewing the module was significant for all three types of academic support websites, it was greatest for contract cheating websites. Significant correlations were also found between the non-planning aspects of impulsiveness (as measured by the Barratt Impulsiveness Scale [BIS-11]; Patton et al. J Clin Psychol 51(6):768–774, 1995) and reputation ratings given for the contract cheating websites. Further study of perceptions (using objective and subjective measures) of contract cheating websites and how aspects of impulsiveness on website perceptions is necessary for the continued development of educational interventions to reduce temptations to engage with the industry. Our study findings contribute to the literature on the promotion of academic integrity and prevention of academic misconduct, particularly contract cheating, through education
Nutrition-related health of children with Trisomy 21 and their lived experience receiving nutrition knowledge and care (NICK): a mixed methods study in Manitoba
Get PDFBackground: Children and adults with Trisomy 21 are more likely than those without Trisomy 21 to develop nutrition-related conditions and diseases. The nutrition-related health of Canadians with Trisomy 21 is unknown. This study aimed to determine the nutrient intake of children with Trisomy 21 living in Manitoba and to identify factors that may influence their nutrition-related health. It also explored the perspectives of parents and caregivers about their child’s nutrition-related health and their lived experience receiving nutrition knowledge and care.
Methods: Mothers of 14 school-aged children (n=7 female, average age 9 years old) with Trisomy 21 completed a 24-hour dietary recall and a survey. Nutrient intake was calculated using FoodFocus Version 4.2, and data were analyzed descriptively. Fisher’s exact test was conducted to test for significant associations between nutrient intake adequacy and factors influencing nutrition-related health. A deductive and inductive thematic analysis approach was used to describe qualitative data. An index (NICK index) to determine nutrition-related health was created as a derived variable computed based on several measures. Results: Intake of sodium, added sugars, and saturated fat was greater than dietary reference intakes. Intake of vitamin D, calcium, and fibre was less than recommended amounts. Intake of iron, protein, and carbohydrate was within recommended amounts. Most children consumed a dietary supplement and engaged in moderate intensity physical activity for over 60 minutes daily. No significant associations were observed between nutrient intake adequacy and factors considered as influencing nutrition-related health. Parents discussed positive and negative experiences receiving nutrition knowledge and care. Nutrition-related health among the children was determined to be less than optimal using the NICK index. Conclusions: The study findings offer a snapshot of nutrition-related health of children with Trisomy 21 living in Manitoba, and their experience receiving nutrition knowledge and care. Together the findings discover a need to improve the nutrition-related health of children with T21 living in Manitoba. Optimizing nutrition-related health of children with T21 may decrease their risk of developing nutrition-related conditions and diseases as they age.February 202
Performance of innovative nanocomposite coatings for concrete protection under harsh exposures of cold regions: field and laboratory studies
No full textConcrete superstructures in cold regions, such as pavements and bridges, experience complex degradation from the combined effects of wet-dry cycles, freeze-thaw cycles, and carbonation in the presence of chloride-based de-icers. Concrete substructures, such as buried foundations and piers, are also vulnerable to sulfates present in soils and groundwater with cyclic environments. The performance of plain and nano-modified coatings as mitigation or rehabilitation strategies for concrete under these combined conditions remain largely unexplored. The current thesis addressed this gap through a systematic evaluation of plain and nano-modified coatings for concrete, including: (i) a one-year field study on 34-year-old bridge deck sections in Winnipeg, Manitoba, Canada; (ii) an 18-month laboratory assessment against magnesium sulfate attack under full immersion and combined exposures; and (iii) a one-year laboratory evaluation under combined exposures, carbonation and calcium chloride de-icer. The results provided fundamental insights into the mechanisms and efficacy of nano-modified coatings in safeguarding concrete under such combined exposures existing in cold regions.
After one year of service, aging bridge deck sections treated with silane, methyl methacrylate (MMA), and nano-silica degraded faster than those treated with ethyl silicate or silane/ nano-clay and silane/nano-silica (2.5% and 5.0% dosages), confirming earlier UM studies; thus, the City of Winnipeg adopted the latter in its rehabilitation specification.
Reducing the water-to-binder ratio to 0.4 improved uncoated concrete’s resistance to magnesium sulfate and calcium chloride under cyclic environments, but surface treatments were still needed for adequate protection. Silane/nanocomposites (2.5% and 5.0% dosages) improved performance against magnesium sulfate through silane’s hydrophobicity combined with the barrier/pozzolanic effects of nano-clay and the filling/buffering effects of nanocalcium carbonate. Vinyl ester and its nanocomposites exhibited superior performance due to the polymeric membrane’s strong bonding and chemical resistance, enhanced by nanoparticles against magnesium sulfate, and are recommended for protecting substructures affected by these conditions.
MMA/nanocomposites did not adequately protect against calcium chloride with carbonation and cyclic exposure due to high solution absorption. Silane/nanocomposites demonstrated superior performance, attributed to the additional barrier/pozzolanic/chloride-binding effects from nano-alumina and filler/nucleation effects from nano-titania. Colloidal silica was inadequate against magnesium sulfate and calcium chloride. Considering durability, cost-effectiveness, and ease of application, silane/nanocomposites at 2.5% dosage are recommended for concrete flatwork in cold regions.February 202
Effects of silver diamine fluoride on oral bacteriome and mycobiome: a randomized clinical trial
Get PDFBackground: Silver diamine fluoride (SDF) is a simple and non-invasive agent used to arrest early childhood caries (ECC). This study aimed to investigate potential changes to the oral microbiome in children with ECC who were treated with SDF and sodium fluoride (NaF) varnish at three different frequency regimens.
Methods: Forty-five children (n = 15 per group) with ECC were recruited from community-based dental clinics in Winnipeg, Canada into an open-label, parallel-group, randomized clinical trial testing three different treatment frequency regimens of SDF. A total of 195 carious lesions were treated with two applications of 38% SDF and 5% NaF varnish (and assessed over three study visits one month, four months, or six months apart. Dental plaque samples were collected at each visit. Sequencing of the V4-16 S rRNA and ITS1 rRNA genes were used to study the supragingival plaque microbiome.
Results: Microbial diversity analyses showed no significant differences in the overall microbiome after SDF treatment. However, significant changes in the abundance of specific bacteria and fungi, particularly Lactobacillus spp., Bifidobacterium spp., and Candida spp., were observed after treatment. Furthermore, overabundance of Streptococcus mutans and Candida dubliniensis at baseline was observed in children who had at least one caries lesion not arrested after one SDF application, compared to those who had 100% arrest rates. The overall arrest rates for treated carious lesions were 75.9% at the second visit and 92.8% at the third visit. Arrest rates were higher for all lesions after two applications of SDF with NaF varnish, and applications one month and four months apart had higher arrest rates (95.9% and 98.5%) than six months (81.1%) apart.
Conclusions: Applications of SDF with NaF varnish were an effective modality for arresting ECC, with higher arrest rates after two SDF applications. No loss of diversity but changes in the abundance of specific bacteria and fungi were observed after SDF treatment.
Trial registration: ClinicalTrials.gove NCT04054635 (first registered 13/08/2019)
Use of prostanoid receptors as a therapeutic target for polycystic kidney diseases
No full textBackground: Beyond tolvaptan, there are no other therapies for polycystic kidney diseases (PKD), a class of inherited cystic kidney diseases. Many of the PKD-inducing mutations translate into changes in cyclic AMP (cAMP) signaling, which is understood to catalyze disease progression. Understandably, discovering novel therapies that lower cAMP is an ongoing endeavor. One approach to rectifying cAMP is interfering with prostanoid (PN) receptors, which influence cAMP metabolism. Elevations in PN have been observed in PKDs and their attenuation with broad cyclooxygenase (COX) inhibitors, is associated with improvements in disease progression. Two PNs, prostacyclin (PGI2) and prostaglandin D2 (PGD2), were shown to be consistently elevated in PKD and responsive to COX inhibition. Objectives & Hypothesis: Therefore, this project strived to identify and test the effectiveness of specific PGI2 and PGD2 receptor drug targets, which may avoid the side effects associated with broad COX inhibition. Methods: A pilot of CD1 Nphp3-pcy/pcy mice was conducted for drug and dosage selection. Drugs affecting PGI2 receptors, but not PGD2 altered renal cAMP and were therefore used for pre-clinical testing in both CD1 Nphp3-pcy/pcy and 129/B6-Pkd1-RC/RC models of early PKD, with tolvaptan serving as a positive control. Results: The IP receptor antagonist, RO1138452, was identified as a potential therapy and created results similar to tolvaptan. Both RO1138452 and tolvaptan administration did not prevent disease progression in early PKD. Conclusions: Findings revealed the importance of PKD progression in pre-clinical drug testing and future testing should be conducted in advanced PKD to assess RO1138452 in the treatment of PKD.February 202
Assessment of warning modalities for remotely supervised autonomous agricultural machines
Get PDFAs autonomous systems gain traction in agriculture, effective human-computer interaction (HCI) frameworks are essential for safe and efficient remote supervision. While autonomous agricultural machines (AAMs) improve productivity, human operators remain vital for monitoring, interpreting warnings, and intervening during system failures. The design of warning systems within human-machine interfaces (HMIs) directly affects operator performance and situation awareness (SA), including perception (Level 1), comprehension (Level 2), and projection (Level 3).
This research investigates how visual, auditory, and tactile warning modalities, used alone or in combination, influence operator awareness and responsiveness during remote AAM supervision. Through simulated field scenarios, participants engaged with unimodal and bimodal cues, with objective measures (reaction time, comprehension, and projection accuracy, CSUQ usability scores) and subjective ratings collected and analyzed.
Bimodal cues enhanced perception. Visual-tactile warnings led to shorter response times than visual-auditory cues in quiet (close-to-field) environments, though no significant difference was found under noisy (in-field) conditions. Both modalities received high usability ratings, with farming participants preferring visual-tactile cues. Among non-farming participants, response times were significantly faster with visual-auditory warnings, t(24) = 3.16, p = .004 (saccadic), and t(24) = 3.56, p = .002 (manual). Projection accuracy was lower for farming participants using visual-auditory cues (86.7%), though not statistically significant, χ²(3, N = 540) = 5.37, p = .147.
Among unimodal cues, visual warnings were most effective across comprehension, urgency perception, and response time, earning the highest user preference (84%). Auditory cues showed moderate performance; tactile cues were least effective. Correlation analysis showed faster comprehension and predicted higher usability, with task accuracy aligning with CSUQ ratings.
Together the findings support the development of adaptive, user-centered HMIs that align warning modality with cognitive and environmental demands. The results of this research contribute to safer, more effective human-robot collaboration in agricultural automation.February 202
Peace is the way: valuing and incorporating a spiritual paradigm in peace and conflict studies
Get PDFOne of the most salient issues the world faces is World Peace. Humans are the only species on the planet who are systemically and intentionally violent with intent to harm and kill. At the same time, there is significant evidence suggesting that humans are inherently peaceful. What then, could account, not for violent behavior, but from preventing us from living peacefully and harmoniously as we were intended to do? Peace and Conflict Studies (PACS) is an academic discipline which has focused on identifying the root causes of conflict and violence with the conviction that by addressing the roots of conflict and violence, peace can ensue. However, the goal to attain positive peace and sustainable peace have remained elusive. Even though PACS theories have been changing and responding to various factors to help address issues that hinder direct and indirect violence, in order to attain peace, this goal has remained elusive. This dissertation is a theoretical investigation and exploration of PACS to understand PACS’ theories from the discipline’s ontological lens. I surmised that PACS’ ontological lens has been grounded in colonial ideology which I have argued is divisive; entangled in violence and has an external focus. These three elements are not grounded in peace; as such, I have made the claim that they can be a hinderance to peace. In light of this observation, I make a case to support my conviction that what is needed in PACS is another ontological lens to understand and know peace – one that is spiritual. From a spiritual lens, peace is characterized by nonduality (which harmonizes us); by ahimsa (a commitment to nonviolence); and by an internal focus (meaning that peace is a practice that comes from consciousness). From a spiritual lens, peace is understood for what peace is, as opposed to what peace is not, i.e. the absence of violence. Thus, in order to understand and learn about peace from a spiritual ontological lens, I develop a spiritual theoretical paradigm and a spiritual conceptual framework for undertaking peace research in PACS.February 202
Three essays on environmental economics
Get PDFThis dissertation examines the effects of three distinct environmental stressors, including air pollution, flooding, and high temperatures, on mortality, educational attainment, and labor supply. It contributes to the broader environmental, health, and labor economics literature by providing causal evidence on previously understudied outcomes. Each chapter focuses on a context and population often overlooked, offering new insights into the human capital and productivity impacts of environmental shocks.
Chapter 1 estimates the causal impact of air pollution on early childhood mortality in Canada using a nationally representative death registry. Leveraging wind direction as an exogenous source of variation in daily PM_2.5 levels, I isolate the effect of both local and non-local pollution sources. A 1 μg/m³ increase in fine particulate matter increases the early neonatal mortality rate per million births by 4.2 percent relative to the three-day mortality rate. Effects are most pronounced above 6.4 μg/m³ PM_2.5 concentrations, supporting the case for more protective air quality standards.
Chapter 2 analyzes the cognitive effects of the 1997 Manitoba flood on children using standardized test data from the National Longitudinal Survey of Children and Youth. I measure flood exposure by distance to the flood polygon and apply a Difference-in-Differences strategy. A 1 km increase in distance is associated with a 0.4-points gain in test scores, with stronger effects for younger and medically vulnerable children. No income-based heterogeneity is observed.
Chapter 3 investigates how heat affects absenteeism among Indian service sector workers, using data from the Indian Human Development Survey-II. A 1°C increase in daily maximum temperature raises teacher absenteeism by 0.6 percentage points, with the effect concentrated in female-majority schools exposed to extreme heat (above 40°C). No significant temperature effect is found for medical staff. Results are robust to alternative heat metrics, including diurnal temperature range and heat index.
Together, these chapters provide new evidence from Canada and India on the pathways through which environmental shocks affect human capital. The findings have clear policy implications ranging from strengthening air quality regulations and disaster preparedness to developing heat adaptation strategies, highlighting the need for environmental resilience in promoting public health, educational outcomes, and labor supply.February 202
Identifying targetable metabolic vulnerabilities for treating brain cancers
No full textBrain tumors account for only 2% of all cancer cases but cause the fourth-highest number of years of life lost to cancer. They are the leading cause of cancer-related death in children, with medulloblastoma (MB) being the most common pediatric brain malignancy. MB tumors arise from errors in early fetal brain development, where the highly aggressive subgroup, group 3 (G3), closely resembles primitive neural stem cells. In adults, glioblastoma (GBM) is the most common brain cancer and has a poor 5-year survival rate of less than 5%. GBM tumors display stem-like cell characteristics and mimic neurodevelopmental hierarchies. Stem-like cancer cells are very aggressive and often less responsive to therapies, posing a major treatment challenge. Survivors of brain cancer often suffer life-long health problems and neurocognitive impairments due to the tumor or cytotoxic treatments. Many patients experience tumor recurrence following initial treatment, with recurrent tumors being almost universally fatal. Hence, there is a critical need for better and safer therapeutic options.
Metabolic reprogramming has emerged as a critical hallmark of cancer. Metabolism can influence cell signaling networks that support tumor cell growth and alter cellular functions. Targeting abnormal metabolic phenotypes is an attractive therapeutic strategy, but it remains unclear how metabolism regulates the aggressive stem-like cell characteristics of brain tumors and helps them resist therapy. This thesis summarizes findings from three studies on the role of metabolism in regulating stem-cell identity and therapeutic responses in GBM and G3 MB brain tumors. The first study reveals a mechanism by which metabolism regulates the stability of the stemness factor and oncogene c-MYC in G3 MB, demonstrating the therapeutic potential of targeting this metabolic vulnerability. The second study explores the distinct metabolic features of GBM stem-like cells and identifies their compensatory responses to metabolic manipulations. The third study uncovers a metabolic adaptation in GBM following chemoradiotherapy that helps maintain stem cell identity by limiting differentiation through epigenetic reprogramming. Blocking this adaptation impaired tumor relapse and prolonged survival in pre-clinical animal models. These findings advance our understanding of metabolism in stem cell signaling networks and identify novel metabolic vulnerabilities for treating aggressive brain tumors.February 202