30921 research outputs found
Sort by
Effects of density and linoleic acid exposure on the chemical profiles of cercarial echinostome parasites
Full text linkFor many 2- and 3-host life cycle trematode parasites, transmission between hosts requires the cercarial stage to emerge from the first intermediate host to infect a second intermediate host or a definitive host. As the role of chemicals in cercarial-host interactions has only been investigated in a few trematode species and in limited contexts, it is unclear if ecological factors affect the diversity of types and concentration of emissions. I investigated the influence of cercarial density and host exposure to linoleic acid on the oxylipin emissions of the trematode parasite, Echinostoma trivolvis lineage c. Using high performance liquid chromatography-tandem mass spectrometry, a total of 40 oxylipins were quantified from nine samples ranging from 363-1621 cercariae per 10 mL, with seven oxylipins being present in ≥75% of the samples. Neither the diversity of types of oxylipins nor their concentrations showed a monotonic relationship with cercarial density, and no linear trends were observed. Forty-seven oxylipins were quantified from four samples of cercariae that each originated from infected snails that were exposed or unexposed to linoleic acid (385-674 cercariae/10 mL and 470-640 cercariae/10 mL, respectively), with 29 oxylipins being quantified in ≥75% of the samples in the unexposed, exposed, or both groups. Among these, oxylipin concentrations between the groups did not differ. Although linoleic acid appeared to be higher in the tissues of exposed snails, this increase did not affect the chemical profiles of the cercariae themselves. My thesis is the first to demonstrate that cercariae of E. trivolvis lineage c emit oxylipins. In addition, this work is the first to test whether density and host diet influence the chemical emissions of echinostome cercariae. By understanding how ecological factors may influence oxylipin emissions of parasites, we can better understand how these chemicals shape patterns of infection, host-parasite dynamics, and ecosystem-level interactions.Research Manitoba Master's Studentship Award
Faculty of Graduate Studies and Postdoctoral Studies Completion ScholarshipMay 202
Mental disorders among emerging adults in Canada: a national study from the mental health and access to care survey
Full text linkBackground and Aims: Mental disorders including generalized anxiety disorder (GAD), major depressive disorder (MDD), and substance use are some of the leading causes of disability worldwide and emerging adults are at greater risk of developing these disorders. The first aim of this study was to examine if having mental disorders increases the odds that a person will have certain substance use behaviours. The second aim was to understand if child abuse and sex moderate, or worsen, the relationship between mental disorders and substance use.
Methods: The current study was a cross-sectional secondary data analysis with data drawn from Statistics Canada’s nationally representative 2022 Mental Health and Access to Care Survey (MHACS). A subsample of emerging adults (i.e., 18 to 29 years old), early emerging adults (i.e., 18 to 22 years old) and late emerging adults (i.e., 23 to 29 years old) were examined in the current study. Risk factors included MDD and GAD separately, MDD or GAD combined, and varying degrees of substance use behaviours. Moderation analyses included an interaction term with main effects of the specific independent variable and moderators (i.e., child abuse or sex). Models with significant interaction terms were conducted stratified to examine the trends. Data analysis included logistic regressions and multinomial regressions adjusting for all sociodemographic characteristics.
Results: Among early emerging adults, only MDD was associated with an increased likelihood of cannabis use, and among late emerging adults, MDD or GAD increased the odds of reporting cannabis and alcohol use at varying degrees. No significant associations were found with binge drinking or AUD. The current study did not find any significant child abuse moderation effects; however, models may have been underpowered to detect a significant effect. Significant sex moderation effects were found in the current study and findings indicate that having MDD increases the odds of varying levels of cannabis use more for females than for males.
Conclusion: These results have important implications for future interventions, treatment programs, prevention strategies, and policy. These include additional training among university and college educators and health care staff, harm reduction strategies, and public health interventions.February 202
Development and validation of improved electromagnetic transient simulation models for solar photovoltaic energy systems
Full text linkSolar photovoltaic (PV) energy systems are central to the transition toward sustainable power generation. However, integrating them into modern power grids requires careful system studies to mitigate potential undesirable impacts. These studies focus on control strategies to maintain grid stability during disturbances and typically conducted using electromagnetic transient (EMT) simulations. Thus, properly parameterized models of key components such as PV modules are essential to accurately evaluate system behavior. The inverter control strategies need to be improved to ensure stability during disturbances.
To address some of these issues, this thesis develops a robust method for extracting parameters of the Single Diode Model (SDM) of monofacial PV modules from data sheet information. The models of bifacial PV modules, whose output depends on both front and rear irradiance, are not well established. Rear-side irradiance and partial shading effects are often inadequately characterized in manufacturer datasheets, leading to performance prediction errors. In this study, the SDM is extended to bifacial modules by incorporating bifacial gain and partial shading effects, and a method to extract model parameters is proposed. Validation of this model is carried out using manufacturer datasheets and experimental data from published sources.
Fast synchronization of solar plants during grid disturbances is critical for maintaining system stability. Frequency measurement accuracy becomes especially important when PV plants participate in power-frequency control, as errors during transients can lead to maloperation. To address these challenges, two key enhancements are proposed to the Double Second Order Generalized Integrator Phase-Locked Loop (DSOGI-PLL). First, a transient elimination mechanism is introduced to detect grid disturbances and temporarily hold the frequency output, thereby preventing erroneous readings. Then, an adaptive bandwidth control strategy is proposed to dynamically increases the bandwidth of the DSOGI-PLL during transients to improved the response time. The proposed DSOGI-PLL is validated in PSCAD/EMTDC using synthetic waveforms, a solar plant connected to a voltage source behind an impedance, and a modified IEEE 9-bus system with solar integration. Furthermore, a power reserve control of solar plant is evaluated to demonstrate its effectiveness in supporting primary frequency response during grid disturbances.UMGF scholarshipFebruary 202
Fault tolerant Euclidean K-Centers
Full text linkThe Euclidean k -center problem is a fundamental question in computational geometry
and facility location. Given a set P of n points in Rd, the goal is to choose
a set F of k center points such that the maximum distance from any point in P to
its nearest center in F is minimized. Geometrically, this corresponds to covering
all points in P with k balls of minimal radius.
We study a natural generalization known as the ℓ-fault-tolerant Euclidean k -
center problem, which introduces a robustness parameter ℓ ≤ k. In this variant,
each point in P must be covered by at least ℓ of the k balls, or equivalently, its
distance to the ℓth nearest center in F must be minimized. This captures scenarios
where redundancy is required for fault tolerance or load balancing.
Our contributions include an exact O(n log n)-time algorithm for solving the
problem in one dimension (R), where a linear order among points can be exploited.
In two dimensions (R2), we prove that the problem becomes NP-hard. Nevertheless,
we present an O(nk/ℓ)-time algorithm that computes a 2-approximation,
offering an efficient and practical solution with provable guarantees.February 202
Fault Tolerant Euclidean K-Centers
Full text linkThe Euclidean \emph{k}-center problem is a fundamental question in computational geometry and facility location. Given a set of points in , the goal is to choose a set of center points such that the maximum distance from any point in to its nearest center in is minimized. Geometrically, this corresponds to covering all points in with balls of minimal radius.
We study a natural generalization known as the -fault-tolerant Euclidean \emph{k}-center problem, which introduces a robustness parameter . In this variant, each point in must be covered by at least of the balls, or equivalently, its distance to the th nearest center in must be minimized. This captures scenarios where redundancy is required for fault tolerance or load balancing.
Our contributions include an exact -time algorithm for solving the problem in one dimension (), where a linear order among points can be exploited. In two dimensions (), we prove that the problem becomes NP-hard. Nevertheless, we present an -time algorithm that computes a 2-approximation, offering an efficient and practical solution with provable guarantees.February 202
Optimizing COVID-19 vaccine strategies: an advanced hybrid entropy decision model for public health evaluation
Full text linkThis study presents a hybrid-entropy-weighted modified TOPSIS framework for evaluating COVID-19 vaccines under differing epidemiological and logistical conditions. Using publicly available data for nine vaccines, eight criteria were examined: efficacy rate, side-effect severity, shelf life, number of doses, cross-protection, regulatory approval, age eligibility, and cost. Two objective weighting methods, Shannon entropy and Wen entropy, were applied. Shannon entropy assigned relatively higher weights to logistical and demographic criteria based on data dispersion, while Wen entropy produced a more even distribution across clinical and dosing related criteria. Adjustable hybrid parameters (φ and λ) were incorporated to allow continuous shifts between emphasizing clinical performance and logistical considerations.
Sensitivity analysis indicated systematic ranking variations as φ changed. Sinopharm and Novavax frequently appeared among the top-ranked vaccines across multiple configurations. Pfizer-BioNTech and Moderna tended to rank higher in low-φ settings that assigned greater weight to efficacy and cross-protection. Sinovac tended to rank higher in high-φ settings that assigned greater weight to shelf life and safety. Scenario-specific recommendations were generated for three contexts: rural and low-resource rollouts, rapid outbreak response, and balanced national strategies.
This framework provides a clear structure for the assessment of vaccines through the combination of objective variability-based weighting systems with adjustable policy priorities, which allows a transparent, adaptable, and context-sensitive multi-criteria decision-making process in public health planning.February 202
Growing together: regenerative agriculture and agritourism as a sustainable future for Caledon Ontario
Full text linkThis practicum investigates the potential of
regenerative agriculture and agritourism in Southern
Ontario as strategies for addressing climate change.
Agriculture in Canada is a notable contributor
to greenhouse gas emissions while also having
significant potential for carbon sequestration and
ecological regeneration. Focusing on Melville Park, a
624-acre site in rural Caledon, this study incorporates
literature review, spatial analysis, and applied design
research to re-imagine farmland as a multifunctional
landscape. The practicum proposes design strategies
that present agriculture as a productive landscape, as
well as a site for education, recreation, and climate
resilience.February 202
Improving transitions between nursing homes and emergency departments: a qualitative study
Full text linkBackground: Nursing home residents with acute illnesses have complex healthcare needs that often require transitions across multiple organizations. This study explores the experiences of diverse healthcare professionals from organizations involved in transitions between nursing homes and emergency departments and identifies conditions necessary to improve this transitional process.
Methods: Eighteen qualitative interviews with healthcare professionals were conducted, and data were analyzed using thematic analysis based on the work of Braun & Clarke. This paper adheres to the Standards for Reporting Qualitative Research (SRQR) standards.
Results: Three themes were identified: (1) Inclusive and supportive engagement, emphasizing the importance of involving care recipients while providing support; (2) Operational readiness, indicating the structures and supports needed to ensure that staff can effectively respond to unexpected events; and (3) Cross-organizational collaboration, pinpointing that streamlined communication strategies across healthcare organizations facilitate a shared decision-making process among healthcare professionals and ensure that essential patient information is readily accessible at each transitional step.
Conclusions: A comprehensive approach addressing these individual, operational, and systemic factors can enhance transitional care between nursing homes and emergency departments
A novel digital twin framework for monitoring inventory and in-bin drying in grain storage
Full text linkThis research addressed the absence of proactive grain storage management methods through the development of a Digital Twin (DT) for grain bins, a previously undocumented approach in academic literature or industry practice. The investigation was guided by, "How can one develop a high-fidelity virtual model with minimal input data that accurately represents real-world conditions and statuses of grain storage bins?" This work established the ``sensorless monitoring'' approach, which required minimal farmer-accessible data to present an inventory status and run simulations capable of predicting future states of grain bin inventory. This approach to inventory management differed from existing technology by providing predictive data for proactive storage. In contrast, modern inventory systems provide reactive data, only alerting users to problems after they occur.
The work began with a theoretical exploration of computer control systems in agriculture, followed by analytical pressure distribution models. Rogers et al. (2024) was developed to describe radial stress variation. Experimental validation of this mathematical model employed a novel tri-axial in-situ pressure sensor, designed and calibrated for this research. Measurements revealed radially variable vertical-to-lateral pressure ratios throughout the silo radius (0.22 near walls, 0.19 in the middle, and 0.37 at the center).
A functional DT platform was successfully implemented as a web application using Streamlit for the front-end interface and Google's Firebase NoSQL server for database architecture. The system featured comprehensive inventory tracking capabilities, including layer-by-layer monitoring of grain properties (commodity type, date of addition, height, mass, moisture content, and bulk density), visual representation of bin contents with colour-coded moisture distribution, and grain addition/removal functionality. The DT integrated pressure calculations based on Rogers et al.'s model, compaction equations, and a prototype drying simulation demonstrating how grain compaction significantly affects drying performance, with simulated differences in moisture content of 3.8% between compacted and uncompacted simulations.
This DT framework represents a significant change from conventional grain management by emphasizing predictive, proactive solutions rather than reactive monitoring with extensive instrumentation. While acknowledging current limitations in sensor design, mathematical modelling, and implementation architecture, this research establishes a foundational framework for future innovations in grain storage management.February 202
Practices and experiences of family caregivers on early mobilization in the cardiac surgery ICU: a mixed methods study of observations and interviews
Full text linkBackground: In the cardiac surgery (CS) intensive care unit (ICU), early mobilization is an established component of postoperative care that supports recovery. Prior research suggests that caregivers often support early mobilization in the ICU. However, little is known about what this support actually involves and there are gaps in documenting caregivers’ perspectives and motivations regarding their role in patient early mobility within the CS ICU. Objectives: The purpose of this thesis was to: (1) observe how caregivers engage in and support patient early mobilization within the CS ICU, and (2) gain insight of caregivers’ understanding, perspectives, and perceptions of their roles in supporting patient early mobilization within the CS ICU. Methods: This mixed-methods study was conducted in the CS ICU at St. Boniface Hospital and combined behavioral mapping/observations (Protocol A) with semi-structured interviews with caregivers (Protocol B). Protocol A consisted of five days of behavioral mapping, each spaced five days apart, to directly observe caregiver engagement in early mobilization activities. Observations were conducted over ten-hour periods (10:00 a.m.–8:00 p.m.), with data collected in 15-minute rounds during which each of the 15 patient beds was observed for 30 seconds. Protocol B followed an interpretive description methodology involving 20 semi-structured interviews with caregivers conducted by one researcher. All interviews were transcribed verbatim, and thematic analysis guided theme development. Results: In Protocol A, 1,140 observations were recorded, including 372 instances of patient mobilization. Caregivers were present in nearly half of the mobilizations (172 counts), most often during the afternoon (12:00–13:59; 45 counts) and evening (18:00–18:59; 44 counts). Sitting in a chair was the most common mobilization activity, representing approximately 80% of all mobilizations. Caregivers primarily provided passive support (137 counts; 79%). Hospital staff were present in 39 of the 172 caregiver-engaged mobilizations, during which caregivers most often demonstrated passive (27 counts; 71%) or active engagement (10 counts; 26%). In Protocol B, five major themes captured caregivers’ perspectives and experiences: (1) Defining Mobilization and Interpreting “Early”, where mobilization included “any movement”, though the concept of “early” was often unclear; (2) Movement Supports Recovery and Health through Progression, where mobilization was linked to physical health, emotional well-being, and visible signs of progress; (3) Emotions and Impressions around Early Mobilization Conceptualization, emotions ranging from feeling prepared and reassured to feeling nervous about whether early mobilization was too soon or unsafe; (4) Experiencing Caregiving – Roles and Emotions in Early Mobilization, which described the balance between helping and fostering independence in their loved ones, while caregivers managed feelings of worry and confidence; and (5) Staff Partnerships Shape Caregiver Engagement, which highlights the caregivers deference on hospital staff guidance and reassurance to engage in early mobilization. Conclusion: Early mobilization is best understood as a flexible, relational process shaped by caregiver priorities rather than a standardized, time-based intervention. Behavioral mapping showed that mobilization was dominated by low-intensity activities, primarily chair sitting and eating or drinking, with caregivers present for nearly half of these events but most often they are providing passive support. Many caregivers did not know what early mobilization meant but recognized that any movement signaled recovery and independence. Their engagement was often limited by uncertainty and lack of guidance. Strengthening education and collaboration between caregivers and healthcare staff can bridge the gap between clinical goals and lived recovery, supporting caregivers as confident, active partners in recovery.Early Mobility To Improve Health Outcomes Following Cardiac Surgery.
Faculty of Graduate and Postdoctoral Studies
Faculty of Kinesiology and Recreation Management
The Graduate Enhancement of Tri-Agency StipendFebruary 202