30921 research outputs found
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Soil and crop responses to normal and shear loading: measurements and discrete element modelling
Get PDFUnderstanding how soils and crops respond to mechanical loading is essential for enhancing agricultural productivity, optimising field operations, and mitigating soil degradation. Mechanical interactions between agricultural machinery and soil, wind and soil erosion involve loading soil with normal and shear forces. However, their impacts on soil and crop have not been systematically quantified. This study examined the dynamic properties of agricultural soils and crop growth (focused on canola, Brassica napus L.) under normal and shear loading. It employed laboratory experiments, field measurements, and Discrete Element Method (DEM) modelling. Laboratory surface shear tests revealed that soil shear strength generally increased in both sandy loam and clay soils when subjected to higher normal stresses. In clay soils, elevated moisture content reduced particle detachment, thereby improving erosion resistance. Laboratory compression and shear experiments showed that bulk density increased across all four soil types (sandy loam, sandy clay loam, clay loam, and clay soils) with increasing normal stress, resulting in greater mechanical impedance. The DEM simulations successfully reproduced observed shear strength trends, confirming the validity of using particle-bonding models for soil-stress interactions. Field cone index tests indicated that compaction consistently raised penetration resistance, with smaller cones exaggerating cone index than larger cones. Laboratory and field studies on canola demonstrated that moderate soil compaction enhanced seedling emergence. However, excessive compaction reduced emergence rate, plant height, and aboveground biomass, constraining crop establishment and growth under field conditions. The integrated experimental and modelling framework advanced the understanding of soil responses and crop interactions under various loading conditions, providing a basis for sustainable soil management strategies.February 202
The association between child emotional abuse and emotional neglect with disordered eating behaviours
Get PDFBackground
Disordered eating behaviours (DEBs) are problematic eating behaviours such as the use of diuretics, self-induced vomiting, and restrictive dieting; however, these symptoms are not present or severe enough to meet a clinical diagnosis. DEBs are associated with adverse health outcomes and may progress to clinical eating disorders. Previous literature shows associations between emotional abuse and emotional neglect with DEBs; however, few studies have examined these associations in Canadian adolescents.
Objectives
The objectives of this study were to: 1) determine the relationship between child emotional abuse (EA) and emotional neglect (EN) with DEBs among a Canadian community sample of adolescents and 2) identify protective factors that decrease the odds of developing DEBs among those with and without a history of any emotional maltreatment (EM).
Methods
Adolescent data were derived from the Wellbeing and Experiences (WE) study. Logistic regression models were run to assess associations between EA and EN with DEBs. Models were adjusted for sociodemographic variables (AOR 1) (i.e., age, household income, sexual identity) and for all child maltreatment types (AOR 2) (i.e., physical abuse, sexual abuse, physical neglect, and exposure to intimate partner violence (EIPV). Analyses were stratified by sex. Possible protective factors that were statistically and potentially clinically significant were also identified in adjusted models (AOR 1) (i.e., age, sex, household income), stratified by histories of EM.
Results
Overall, 24.5% of adolescents reported any form of EM, 21.7% reported EA, and 13.3% reported EN. Females reported more DEBs than males (67.5% vs 32.6% ). EA, EN, and any EM were significantly associated with DEBs in the unadjusted models (OR range 4.47-10.04) and adjusted models among both the males and females (AOR 1 range 3.44-7.31). After adjusting for all child maltreatment types, only EM remained statistically significant for both sexes. Several statistically significant and clinically significant protective factors were associated with increased odds of no DEBs, though many models may have been underpowered.
Conclusions
These findings emphasize the need to better understand DEBs in adolescents, particularly their associations with EA and EN, and to identify protective processes that can guide prevention and early intervention efforts.February 202
Spatial variation in trophic interactions, food web properties, and community composition around the Belcher Islands, Nunavut
Get PDFArctic marine food web structure and function are influenced by climate-driven change and anthropogenic stressors, leading to fine-scale environmental gradients and shifts, yet these dynamics remain poorly understood in Hudson Bay. Around the Belcher Islands in southeastern Hudson Bay is the proposed Qikiqtait study area of conservation interest and is an important area for the community of Sanikiluaq, where invertebrates, fish and marine mammals are all harvested. Qikiqtait is a unique marine area due to strong upwelling and relatively colder surface water temperatures, which lead to increased mixing and therefore increased nutrient availability and productivity. However, the hydrological cycle is changing due to increasing freshwater inputs, resulting in spatially and temporally variable primary production around the islands. Yet, knowledge of fine-scale spatial (tens to hundreds of kilometres) distributions in carbon source use, community composition and trophic interactions from invertebrates to marine mammals are scarce and understudied. Using a collection of complementary biotracer tools, community metrics, environmental data, and network analyses, I quantified spatial variation in food web structure, carbon pathways, and community composition across major taxonomic groups including benthic and pelagic invertebrates, fish, and marine mammals. The marine environment north of the Belcher Islands was cooler and more saline, with less pelagic primary production availability compared to the south, where the marine environment represented more freshwater influences, with warmer and less saline water and greater concentrations of pelagic primary production indicators like colour dissolved organic matter (CDOM) and chlorophyll-a. North of the islands supported higher benthic fish richness, shrimp and stalked tunicate dominance, and an overall greater reliance on sympagic (sea ice algae-derived) carbon, whereas the south supported dominance by brittle stars and Arctic cod (Boreogadus saida), and relatively greater trophic positions. Sympagic carbon reliance ranged from 13.09% to 73.43% in euphausiids (Thysanoessa sp.) and bearded seals (Erignathus barbatus), respectively, with relatively greater proportions north of the islands in benthopelagic fish, sessile invertebrates, molluscs and decapods. Trophic positions ranged from 1.97 (molluscs) to 4.28 (beluga whales (Delphinapterus leucas)), with generally higher values in sessile invertebrates, decapods, and echinoderms in the south, except for jellies, which had higher trophic positions in the north. Food webs in the north had greater richness and benthic connectors, while the south had a mix of benthic and pelagic connecting species, yet connectance was similar. This study provides the first comprehensive characterization of the Qikiqtait food web at fine spatial and taxonomic scales, and is the first in an Arctic ecosystem to apply such a broad and integrative suite of state-of-the-art methods on such a wide range of species. This study demonstrated how local nutrient availability shapes community composition and resource use, and these insights advance our understanding of the mechanisms structuring Arctic ecosystems and inform conservation and management efforts.February 202
Clinical trials of L1 (Deferiprone) at the Hospital for Sick Children in Toronto: a review of facts and circumstances
Get PDFThe Board of Trustees of the Hospital for Sick Children, prompted by the current controversy involving Dr. Nancy Olivieri, The Hospital for Sick Children and Apotex Inc. , wished to have its policies, procedures and practices subjected to an independent external review. The Board decided that the review should proceed in two phases. The mandate for the initial phase of external review was established by resolution of the Board of Trustees at a meeting on September 8, 1998. The resolution states: Be it resolved that the mandate for Part 1 of the Independent External Review authorized by the Board of Trustees be as follows:
Part 1: L1 Clinical Trials
To conduct an independent review to determine the facts and circumstances giving rise to the current controversy involving Dr. Nancy Olivieri, The Hospital for Sick Children and Apotex Inc. including matters pertaining to the following:
• Patient Safety at The Hospital for Sick Children
• Conflicts of Interest
• Release and Publication of Research Information
Upon completion of the Review which is expected by November 30, 1998, the Reviewer will report his findings to the Board of Trustees. The report of his findings will then be made public by the Board
Evaluating the efficacy of a novel home-based oral food challenge protocol for pediatric food protein induced enterocolitis syndrome
Get PDFBackground: Oral food challenges (OFCs) are considered the gold standard for diagnosis of food protein–induced enterocolitis syndrome (FPIES), a non-immunoglobulin E mediated gastrointestinal food allergy characterized by delayed, repetitive vomiting, lethargy, and sometimes diarrhea, primarily affecting infants and young children. Our modified approach to OFCs involves smaller, gradually increased doses to mitigate the risk of severe reactions. We aimed to measure the successful completion of this OFC protocol.
Methods: In a retrospective chart review, patients age < 18 years, who had 1 + episode of acute FPIES between 2015 and 2023 were identified using an allergy clinic database. Patients underwent OFCs with home up dosing every 2–4 weeks. Steps included 1%, 2%, 5%, 10%, 20%, 30%, 40%, 60%, 80%, and 100% of the final serving amount. The primary outcome was successful completion, i.e. absence of severe reactions during the OFC protocol and 1 year after. Data were analysed using logistic regression and reported as odds ratios (OR) and 95% confidence intervals (95% CI).
Results: were adjusted for multiple allergic comorbidities, age of FPIES onset, and biological sex. Results Among 47 patients who began the OFC protocol, 38 (80.85%) completed it without significant reactions. Of the 9 (19.14%) who did not complete the protocol, 4 (44.4%) paused due to reactions, and 5 (55.6%) paused due to non-FPIES symptoms. The 4 reactors paused due to mild-to-moderate reactions; there were no severe reactions during the protocol. There were no significant associations identified between OFC completion and severity of symptoms (OR 1.05; 95% CI 0.24–4.71; p = 0.94); age at onset of symptoms (OR 0.99; 95% CI 0.94–1.02; p = 0.58); or age of starting OFC (OR 1.00; 95% CI 0.98–1.02; p = 0.90). Patients who reacted to milk tended to be less likely to complete the protocol than those reacting to other foods (OR 0.28; 95% CI 0.07–1.06; p = 0.06).
Conclusions: This study supports the potential for a home-based gradual approach to OFCs in FPIES, evidenced by a high completion rate and no severe reactions
Collage and space in landscape architectural imagination and representation
Get PDFThis thesis explores the role of collage-making as a creative tool in the design process for landscape architecture. It posits that collage offers a unique way for exploring project briefs and site-specific surveys, empowering landscape designers to openly interact with a site’s spatial and temporal dynamics. The study then ventures into the potential of Artificial Intelligence (AI) in generating landscape architectural imagery, creating a new form of collage as a type of composite image that activates and supports creativity. The convergence of human cognition and AI engines as analytical tools represents a new development in landscape architecture. By reviewing literature and analyzing case studies, this research underscores the practical significance of collage and a set of criteria for its interpretation in enhancing spatial imagination and representation in the design process of landscape architecture. Collage, as an expressive art form, and the text-to-image generation AI tool Midjourney share traits that are critical for landscape architectural ideation. Designers’ interpretations of sites and project briefs guide collage-making, anchoring and infusing design ideas and temporal concepts into a specific context. Similarly, Midjourney’s renderings reflect designers’ written prompts and selected images, unveiling intentional choices in how the context is understood, visualized, and reimagined. In comparison to Midjourney, which obscures how word compositions transform into spatial qualities and characteristics, collage-making demands considerable intentionality and vigilance. Approaching any representational tools with caution, recognizing their limitations and potential pitfalls, is vital to imagining new possibilities. As part of the design process, analogue collage and AI images serve as tools to foster intentionality and creativity, rather than a projection of final renderings of the accepted design. A critical understanding of context, the deliberate use of descriptive words and image fragments, and their juxtaposition within collages exist in a delicate balance with site-specific questions that are difficult to reconcile in standard screen-generated representations. This visualization process demands time and considerable engagement, a dynamic that evolves with image generating platforms like Midjourney, which requires constant, informed input to produce relevant image iterations. This thesis proposes pathways for interpreting collage to bridge the gap between landscape descriptions and images, fostering a deeper understanding of site surveys, project briefs, and visual iterations. It positions collage as an important tool to enrich the design process in landscape architecture. The work and writings of James Corner (1996, 2014) are central to this argument. He examines the agency of landscape and how individuals and groups value, perceive, and interpret nature, space, and time. Of particular interest is how Corner critiques the limitations of Cartesian mapping relative to site-specific perception, emphasizing collage and the temporal aspects of his eidetic ‘discovery measures’ to enrich spatial interpretations in landscape design. Examined through the lens of the philosophy of perception, eight interconnected criteria — ideas of space, emotion, reference, context, method, aspiration, audience, and neutrality-priority paradox — underlie intuitive yet contextually grounded interpretations of collages. They serve as eidetic entry points to investigate notions of spatial order in landscape representations. Based on these criteria, the thesis examines collages by the Situationist International (SI) and other utopian movements that challenged the implied order within conventional maps. Corner’s writings offer unique critical insights into how eidetic perception and spatial representation dynamically influence landscape interpretation, integrating site-specific factors that shape and give form to lived experiences. Seeking out and building upon these otherwise repressed ‘discovery measures’ in the landscape design process, this thesis explores how AI prompts and renderings can resonate with the lived experience of a given site. The thesis offers a framework to emphasize the human designer’s agency in the collaborative integration of AI within the design process. While maps and plans cannot fully convey the temporal complexities of site-specific perceptions and/or their social cultural contexts to which they come attached, they can be explored through a collaboration between collage-making and AI-enhanced renderings.University of Manitoba Graduate Fellowship - UMGF 2019-2021February 202
Investigating markers of Alzheimer’s disease in posttraumatic stress disorder using machine learning and magnetic resonance imaging
No full textIntroduction: Posttraumatic stress disorder (PTSD) is a mental health disorder caused by experiencing or witnessing traumatic events. Recent studies show that patients with PTSD have an increased risk of developing dementia, including Alzheimer’s disease (AD), but there is currently no way to predict which patients will go on to develop AD. The objective of this study was to identify structural and functional neural changes in patients with PTSD that may contribute to the future development of AD.
Methods: Neuroimaging (pseudo-continuous arterial spin labelling [pCASL] and structural magnetic resonance imaging [MRI]) and behavioral data for the current study (n = 67) were taken from our non-randomized, open label clinical trial (ClinicalTrials.gov Identifier: NCT03229915) for treatment-seeking individuals with PTSD (n = 40) and age-matched healthy controls (HC; n = 27). Only the baseline measures were utilized for this study. Mean cerebral blood flow (CBF) and grey matter (GM) volume were compared between groups. Additionally, we utilized two previously established machine learning-based algorithms, one representing AD-like brain activity (Machine learning-based AD Designation [MAD]) and the other focused on AD-like brain structural changes (AD-like Brain Structure [ABS]). MAD scores were calculated from pCASL data and ABS scores were calculated from structural T1-MRI images. Correlations between neuroimaging data (regional CBF, GM volume, MAD scores, ABS scores) and PTSD symptom severity scores measured by the clinician-administered PTSD scale for DSM-5 (CAPS-5) were assessed. Results: Decreased CBF was observed in two brain regions (left caudate/striatum and left inferior parietal lobule/middle temporal lobe) in the PTSD group, compared to the HC group. Decreased GM volume was also observed in the PTSD group in the right temporal lobe (parahippocampal gyrus, middle temporal lobe), compared to the HC group. GM volume within the right temporal lobe cluster negatively correlated with CAPS-5 scores and MAD scores in the PTSD group.Conclusion: Results suggest that patients with PTSD with reduced GM volume in the right temporal regions (parahippocampal gyrus) experienced greater symptom severity and showed more AD-like brain activity. These results show potential for early identification of those who may be at an increased risk for future development of AD.University of Manitoba Graduate Fellowship, Society for Neuroscience Trainee Professional Development Award, Workers Compensation Board of ManitobaMay 202
Development and characterization of a mouse model for in utero type 2 diabetes exposure
Get PDFBACKGROUND: The prevalence of childhood type 2 diabetes (T2D) in Canada, and particularly in Manitoba, is amongst the highest worldwide, resulting in an increased incidence of pregnancies complicated by T2D as children approach their reproductive years. Exposure to T2D in utero has detrimental effects on the health and well-being of offspring, including various malformations, stillbirth, congenital defects, metabolic disorders, a significantly higher predisposition to diabetes, early kidney failure, chronic low-grade inflammation, cardiovascular issues, mental health issues, and cognitive deficits. However, the mechanisms responsible for poorer health outcomes in T2D-exposed offspring and greater intergenerational risk remain unclear. To investigate the effects of maternal T2D on offspring physiology and health, an appropriate T2D mouse model is required. Existing approaches to induce T2D in mice often result in hypoinsulinemia and severe hyperglycemia, which does not accurately resemble T2D in humans. These approaches to induce T2D typically lead to offspring microsomia, whereas human offspring of T2D mothers often have macrosomia. Genetic models of T2D models either produce infertile mice or induce diabetes in males only, making it impossible to study the effects of in utero T2D exposure on offspring. Therefore, the development and characterization of an appropriate rodent model of T2D that can be used during pregnancy and more accurately resembling T2D in humans, is needed to effectively investigate the mechanisms responsible for the intergenerational transmission of T2D and mechanistic contributors to adverse health outcomes in exposed offspring.
METHODS: To develop a model of T2D pre-pregnancy, female C57BL/6J mice were exposed to a high-fat and sucrose (HFS) diet for varying durations (4, 6, 8, and 10 weeks) to induce obesity and insulin resistance. Subsequently, a one-time administration of different concentrations of streptozotocin (STZ; 75 mg/kg, 100 mg/kg, or 150 mg/kg), a chemical that specifically targets and kills pancreatic β-cell, was used to impair adaptive beta cell function without completely eliminating the β-cell pool. Weekly body weight and biweekly fasted blood glucose measurements were performed on all female mice. Two weeks after the STZ injection, the mice underwent glucose metabolism assessments, including a glucose tolerance test (GTT), insulin tolerance test (ITT), and weekly fasted blood glucose and body weight measurements. Control mice were fed a chow diet and injected with citrate buffer (the vehicle for STZ) and underwent metabolic assessments alongside the T2D groups. After pre-gestational metabolic assessments were completed, female mice were mated with healthy chow-fed C57BL/6J male mice. Maternal glycemia and body weight were measured during each trimester of gestation (weekly). Additionally, an HFS-only control group (no STZ) was established to determine the impact of the HFS diet alone. These mice were placed on the HFS diet for 10 weeks and then injected with vehicle (citrate buffer) and metabolically assessed.
RESULTS: The study revealed that female mice fed an HFS diet for 10 weeks prior to a 150 mg/kg STZ injection developed mild-to-moderate fasted hyperglycemia, glucose intolerance, insulin resistance, and higher fasted glycemia, which was maintained throughout gestation compared to control mice, indicative of pre-existing T2D prior to pregnancy and T2D throughout pregnancy. In contrast, the HFS-only control group of mice, while showing increased body weight, developed less glucose intolerance and maintained euglycemia, suggesting that the reduction of β-cell mass via STZ was needed for T2D development in C57B6 female mice.
CONCLUSIONS: These findings suggest that through a combination of an HFS diet (10 weeks) and STZ injection (150 mg/kg of STZ), T2D that includes key features of human T2D can be generated in female C57BL6 mice while maintaining fertility. This model can be used to study the effects of in utero exposure to T2D on offspring development and function, while also identifying pathophysiological mechanisms underlying structural and functional changes. This information gained from the use of this model has the potential to contribute to various therapeutic approaches, the development of new drugs, and the adjustment of current clinical protocols, among other potential outcomes.UMGF
Supervisor's funding
Janice Dodd Prize for Excellence in Endocrine PhysiologyFebruary 202
Exploring Manitoba's Visitation Shelters/Pods at Personal Care Homes
Get PDFThe Centre on Aging conducted a study on outdoor visitation shelters/pods at personal care homes (PCH) in Manitoba. The aim of this research project was to evaluate the experiences of visitors, staff/operators/volunteers, and residents who had used the visitation shelters/pods. Eligible participants had to be 18 years or older
Sites of resistance: disability and inclusion in Canadian K-12 education
No full textIf there was a country called disabled, I would be from there. (Frazee, 2023, p. xv)
Ableism in Canadian K–12 education remains pervasive. As a site of resistance, this research explores the ways in which ableism is manifest in schools while offering recommendations for transformative praxis. This research is comprised of an autoethnography, policy analysis, and case study as a manuscript-style dissertation. Overall, these three research studies contribute to the continued rupture of ableism and disability marginalization in Canadian K–12 schools. Most importantly, this dissertation contributes to a growing understanding that there is nothing wrong with being disabled or being part of the disability community (Kafai, 2021). Concurrent themes that flow through this dissertation include: the importance of voice, equitable representation, empowerment, knowledge, identity, and calls for transformation. This research seeks to contribute to the field of inclusive education and critical disability studies in Canada.February 202