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Optimal generalized shrunken least squares estimator in linear models
No full textIt is widely acknowledged that, in a linear model, when the predictor variables are highly correlated so that the design matrix is nearly singular, the Ordinary Least Squares (OLS) estimator may have poor performance due to its large variance and numerical instability. The problem is particular acute in modern times where models with large number of variables are routinely used. To address the issue of multicollinearity, linear biased estimators have received significant attention in the literature. This study focuses on the class of Generalized Shrunken Least Square (GSLS) estimators that contain various popular biased estimators as special cases. In particular, we derive the optimal GSLS estimator and develop an effective algorithm for its numerical calculation. Comprehensive simulation studies are conducted to evaluate and compare the performance of the proposed optimal estimator with other estimators across varying multicollinearity scenarios under the mean square error (MSE) criterion. Real data applications are also presented to demonstrate the usefulness of the proposed method.October 202
Enabling permissioned-to-permissionless blockchain interoperability with enhanced privacy and incentive mechanisms
No full textInteroperability between blockchain networks is a critical capability for enabling autonomous blockchain systems to communicate and exchange information. Bridging a permissioned network with a permissionless network introduces unique challenges, particularly in safeguarding the privacy and anonymity of stakeholders within the permissioned network, where stricter privacy and governance requirements apply. This thesis presents a relay-based architecture that facilitates secure interoperability between these two categories of blockchains while mitigating privacy risks inherent in such cross-chain interactions. The relay layer comprises autonomous blockchain nodes that operate independently of both networks. To incentivize active and reliable participation, we propose a hybrid incentive mechanism incorporating a trust score to quantify and reward the reliability and trustworthiness of each node. The proposed mechanism is evaluated under a defined threat model, with security risks systematically identified and addressed. Finally, the architecture is assessed in terms of both performance and its effectiveness in preserving privacy and anonymity.February 202
1,7-Dihalogenated BODIPYs: Synthesis, Structure and Photophysics
No full text4,4-Difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) and its derivatives are highly useful fluorescent dyes employed in myriad applications in chemistry and biology. Here, we revisit a series of dihalogenated (Cl, Br, I) BODIPY derivatives with rare 1,7- regiochemistry. In addition to their synthesis and structural characterization, we fill in a missing piece of the current literature by delineating their photophysical behaviour, including the light-driven generation of singlet oxygen (1O2) which is mediated with particularly high efficiency by the heavier diiodinated congener
Six aspects of justice as a grounding for analysis and practice in social work
No full textThis manuscript explores how the question of social justice is approached by some major social work theorists in the anti-oppressive practice school. The manuscript then draws on ideas from moral and political philosophy and from critical social theory with a view to broadening and deepening social work’s theorisation of social justice.
The manuscript points to six ideas that can enhance our thinking about social justice in social work theory: i) justice as equality based on the inherent worth and dignity of all human beings, and the rights that adhere to them; ii) justice as (relative) equality through economic redistribution; iii) justice as the flourishing of all species in a healthy and sustainable (natural and built) environment; iv) justice as moral integrity; v) justice as fairness; and vi) justice as restoration and healing.
A broad and nuanced understanding of "social justice" in social work is more necessary than ever, as we carry out our work in the challenging contemporary circumstances of social injustice
Role of pentraxin 3 in type-2 low asthma
No full textAsthma is a heterogeneous chronic inflammatory disease of the airways, characterized by variable airflow obstruction, bronchial hyperresponsiveness, and inflammation. While type 2 high asthma characterized by eosinophilia and Th2 cytokines is relatively well understood and responsive to corticosteroids and targeted biologics, type 2 low asthma remains poorly defined and is often associated with neutrophilic inflammation, steroid resistance, and a lack of effective targeted therapies. Therefore, identifying key molecular players in type 2 low asthma is critical for advancing our understanding and treatment of this subtype. PTX3, a soluble pattern recognition receptor and a member of the long pentraxin family, plays a pivotal role in innate immunity, inflammation regulation, and tissue homeostasis. Despite its involvement in several inflammatory disorders, the role of PTX3 in asthma particularly type 2 low asthma has not been fully elucidated.
We began by analyzing PTX3 expression levels in BAL fluid and serum samples from asthmatic patients and found significantly elevated PTX3 concentrations in asthmatics compared to healthy controls. To further investigate the mechanistic role of PTX3, we employed a chronic HDM plus c-di-GMP exposure model in mice, which recapitulates many features of type 2 low asthma. Using PTX3-deficient mice, we observed markedly increased total lung resistance, enhanced neutrophilic inflammation, and elevated levels of interleukin-17A and suggesting a regulatory role for PTX3 in controlling neutrophil-driven responses.
Interestingly, PTX3-/- mice also exhibited increased total and HDM-specific IgE levels, pointing to a potential role for PTX3 in modulating allergic sensitization. In contrast, treatment with rhPTX3 paradoxically intensified airway inflammation and neutrophil and eosinophils recruitment but resulted in reduced airway resistance and tissue elastance, highlighting a complex and context-dependent function for PTX3 in regulating both immune responses and lung mechanics.
Together, these findings suggest that PTX3 serves as a key immunomodulator in type 2 low asthma, balancing pro-inflammatory and tissue-protective effects. This dual role emphasizes the importance of context and timing in PTX3’s function and underscores its potential utility as both a biomarker and a therapeutic target in asthma, particularly in phenotypes unresponsive to conventional corticosteroid therapy.October 202
Impacts of organic farming on zinc and iron bioavailability in edible crop parts: evidence from long-term field study and meta-analysis
No full textZinc (Zn) and iron (Fe) deficiencies are prevalent health concerns across the world, especially in populations that rely heavily on plant-based diets. Organic agriculture is often considered one of the most promising agronomic strategies for enhancing the nutritional quality of crops. This thesis evaluates the effects of organic farming on Zn and Fe concentrations and their bioavailability in edible crop parts through a long-term field study and a comprehensive global meta-analysis.
In the long-term field study, spring wheat (Triticum aestivum L.) grain produced under organic management exhibited higher Zn concentration than conventionally grown wheat, particularly when perennial crops like alfalfa were included in the rotation. Organic systems with annual-perennial crop rotation also significantly decreased grain phytate concentration, leading to enhanced bioavailability of Zn and Fe. However, these micronutrient benefits were accompanied by reduced crop yield, primarily due to phosphorus (P) limitation. While compost application significantly improved wheat productivity, it simultaneously increased grain phytate concentrations, thereby diminishing the beneficial impact on micronutrient bioavailability.
The global meta-analysis included 322 paired observations from 54 peer-reviewed studies. The results further confirmed an average increase of 14.2% in Zn concentrations in the edible parts of organically produced crops, with vegetables showing the strongest responses. No overall statistically significant increase in Fe concentrations was observed, except in high precipitation regions where organic crops showed significant higher Fe concentrations in edible crop parts. Despite these micronutrient improvements, organic agriculture exhibited an average yield penalty of 24.7%, with the most notable reduction observed for cereals and in arid regions.
Our research revealed the potential of organic agriculture to produce crops with greater micronutrient concentrations and bioavailability in their edible parts, but this nutritional advantage is frequently accompanied by significant yield trade-off. The findings underscore the necessity of integrated soil fertility and crop management strategies, such as selecting organic amendment types with higher micronutrient but lower P levels, and breeding crop ideotypes with enhanced P uptake but reduced P accumulation/translocation into crop edible parts under low soil P conditions. Overall, this thesis work provides valuable insights for guiding organic agriculture practices aimed at reducing the global micronutrient deficiencies.October 202
Unionization as a community-based intervention against the precarious employment of Filipino immigrant women in the garment industry: a case study of the Canada Goose Workers’ Union in Winnipeg, MB
No full textThe rise of neoliberalism in Canada in the 1980s has intensified a specific formation of precarious employment which disproportionately affects female, racialized workers, including Filipino immigrant women. Historically, this has been true for the garment industry of Winnipeg, which has long employed female migrant workers from various ethnocultural communities, including Filipino migrant women workers. Previous literature on precarious employment points to the positive effects of unions in improving the precarious conditions disproportionally faced by racialized and gendered workers, but is complicated by barriers to unionization faced by these workers and recent declines in unionization rates in Canada. However, in 2021, garment industry workers in Winnipeg’s Canada Goose plants successfully organized and formed the Canada Goose Workers’ Union under Workers United Canada Council. Using a qualitative, community-based approach in collaboration with Canada Goose Workers’ Union, this research aims to study unionization as a community-based intervention against the precarious employment of racialized immigrant women workers in the garment industry through a case study of the recently formed Canada Goose Workers’ Union in Winnipeg. Rooted in a feminist political economy (FPE) approach, the objective is to document the union certification process, and to understand whether unionization and collective bargaining have affected the degree of precarity that Filipino immigrant women workers tend to disproportionately experience within a neoliberal context. This study found that social locations such as gender, race, and citizenship were fundamental to shaping the precarious conditions experienced by the workers at Canada Goose, which compelled them to begin a union drive in 2019. The results of this research point to the role that unions play in determining the conditions of work and life of Filipino immigrant women. Unions therefore must employ an intersectional approach to organizing and representing immigrant women workers, whose identities play a fundamental role in shaping their economic conditions in Canada.Manitoba Research AllianceFebruary 202
Ingestion and impacts of microplastics on the plankton food web in a whole-lake addition experiment
No full textDespite the prevalence of microplastics in the environment, their fate and effects on aquatic ecosystems are largely unknown. At the International Institute for Sustainable Development - Experimental Lakes Area (IISD-ELA) in northwestern Ontario, Canada, a long-term study is being conducted involving three years of microplastic additions to an entire lake. This thesis uses data collected from the experimental lake, Lake 378, and a nearby unmanipulated lake, Lake 373, to examine how microplastics may affect the planktonic food web, including phytoplankton, zooplankton, and a dominant invertebrate predator, the dipteran Chaoborus spp.. In Chapter 2, the ingestion of microplastics by zooplankton and Chaoborus spp. in the experimental lake was investigated to determine how microplastic ingestion varied temporally, spatially and across taxa. On average, 0.007 ± 0.015 microplastics/zooplankton were encountered in the guts of zooplankton. Ingestion varied among zooplankton taxa and was closely related to concentrations in the water column, emphasizing that sampling in other systems should consider these variations. Differences between the microplastics ingested by crustacean zooplankton and Chaoborus spp. suggested minimal trophic transfer. As well, we contextualized planktonic organisms as a biotic compartment for microplastics and determined that few microplastics were encountered in zooplankton as a repository compared to other matrices. In Chapter 3, data from the experimental lake and reference lake collected during four baseline years and two post- addition years were used to assess the effects of microplastics on the planktonic community using a Before-After-Control-Impact (BACI) design. Changes to all three groups of organisms were observed relative to baseline levels and the reference lake suggesting microplastic pollution may have effects on these organisms in natural settings. Changes in the plankton community were relatively small and some may have begun prior to the initiation of microplastic additions. Analyses in subsequent years will help to further elucidate the microplastic impacts. Statistically significant decreases in individual lengths and overall population biomass of Chaoborus spp. were also observed in the second year of additions (2024), suggesting a potential time lag. This whole-lake manipulation experiment is the first of its kind to use microplastics and will inform industry and government level policies to mitigate microplastic pollution.M.M was funded by National Sciences and Engineering Research Council of Canada (NSERC CGS-M), the University of Manitoba (Faculty of Graduate Studies Research Completion Scholarship and Tri-Agency Master’s Top up and Supplement Awards), and the International Institute for Sustainable Development - Experimental Lakes Area (IISD-ELA) (Graduate Fellowship). The overall project was funded by Loblaws, Environment and Climate Change Canada (ECCC), and the National Sciences and Engineering Research Council of Canada (NSERC Alliance).October 202
Investigating transmission pathways of a nosocomially transmitted fungal infection
No full textThis thesis investigates the transmission dynamics of nosocomial fungal infections such as Candida auris, a multidrug-resistant pathogen increasingly observed in intensive care units (ICUs)-using both deterministic and stochastic (continuous-time Markov chain, CTMC) modelling approaches. Our compartmental framework includes patients, healthcare workers (HCWs), and the ICU environment, capturing multiple transmission pathways between these vectors. We examine outbreak dynamics through extinction analysis, basic reproduction number, sensitivity testing, and two-dimensional parameter interaction heatmaps. Our results show that environmental contamination and undetected infectious patients are primary drivers of transmission, with patient-origin outbreaks showing low extinction probabilities.October 202
Prototyping passive and active cavity magnonic devices
No full textMicrowave technologies form the foundation of modern communication, radar, and sensing systems. Magnetic materials, particularly ferrites, have long served as key components in microwave devices such as isolators, filters, and oscillators. Their low loss and frequency tunability remain essential for controlling and manipulating microwave signals.
In recent years, cavity magnonics has emerged as a promising platform that harnesses the interaction between microwave cavity and magnetic excitations. The interaction produces hybridized states that combine the mobility of photons with the coherence of spins, enabling new device concepts and functionalities. Originally studied in spintronics, cavity magnonics has since revealed novel effects that go beyond the capabilities of conventional microwave components.
This thesis investigates two such phenomena: non-reciprocal transmission and coherent microwave emission. First, an isolator prototype is demonstrated, achieving strong signal isolation with low insertion loss, representing a step toward compact and efficient non-reciprocal devices. Next, a microwave oscillator is developed and coupled to ferrite material, revealing a phase noise suppression effect that produces a sharp emission spectrum, establishing a pathway to low-noise microwave sources.
Together, the thesis demonstrates how cavity magnonic systems can progress from proof-of-concept studies to practical device applications, opening new opportunities for the development of next-generation microwave electronics.February 202