30921 research outputs found
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The effects of topically-applied double-stranded RNA pesticides on Myzus persicae
Get PDFThe green peach aphid (Myzus persicae) is a major agricultural pest, causing billions in crop losses and contributing to global food insecurity. Increasing incidences of insecticide resistance and off-target effects highlight the need for alternative control methods. RNA interference (RNAi), a gene-silencing mechanism triggered by exogenous double-stranded RNA (dsRNA), has emerged as a promising approach to species-specific pest control.
Topically applied dsRNA offers a non-GMO alternative to traditional pesticides, selectively inducing mortality in pests by targeting essential genes. One such gene, Chitin Synthase (CHS), is crucial for the insect exoskeleton, tracheae, and gut. However, dsRNA penetration through the aphid’s hydrophobic exoskeleton remains a challenge, necessitating delivery enhancements like surfactants.
This study tested two dsRNA structures—long linear dsRNA (210 bp) and short paperclip RNA (pcRNA, 25 bp)—targeting CHS, with and without the surfactant Silwet. Third-instar aphids were topically treated with a dsRNA droplet, and their survival and fecundity were monitored over eight days. Several bioassay optimizations were implemented, including stretching diet packets, treating third instars instead of adults, filter-sterilizing diets, and chilling aphids before treatment.
Bioassays demonstrated that dsRNA + Silwet significantly increased aphid mortality, whereas dsRNA alone and all pcRNA treatments had no significant effects. No significant fecundity reduction or CHS gene knockdown was observed. While only a single gene target was assessed, findings suggest RNAi-based pesticides hold potential for aphid control, and Silwet improves dsRNA efficacy. Further research on optimizing dsRNA formulations could enhance their application as next-generation pesticides
Redefining local space with mindfulness and movement: a design approach for an urban literary centre
No full textThis practicum explores a reimagination of the public library typology as a multi-use literary centre to become a beneficial destination for the urban community. While libraries have been around for millennia, their use in contemporary society has shifted, requiring them to expand their programmes and present greater adaptability. It is a beneficial endeavour to rethink how the public library can evolve to become a more utilised place for city locals and visitors. The purpose of this research is to analyse how interior design can enhance the public library to promote urban development, facilitate community connections, and improve individual wellbeing and experience through researched design initiatives.
Theories and design strategies will be analysed, including social infrastructure, adaptable mixed-use, and holistic design, public space and social placemaking theories, as well as salutogenic design theory that examines sense of place, and biophilic design. Alongside the books, a design will be implemented to create spaces for several activities. These consist of a reader’s café and garden, gift shop, events area, galleries, multipurpose classroom, collaborative spaces, music rooms, and a wellness studio. This research will be implemented to create a model for a new vision of the public library within an existing building in the City of Winnipeg, ideally inspiring a brighter future for library design.University of Manitoba Faculty of Graduate Studies - University of Manitoba Graduate Fellowship (UMGF)
University of Manitoba Faculty of Architecture - Roy C. Rettinger Graduate Scholarship for Interior DesignOctober 202
Modelling soil-residue-machine interactions using the discrete element method (DEM)
No full textA comprehensive understanding of the interactions between soil, crop residue, and tillage implements is critical for advancing the efficiency and sustainability of conservation agriculture. This study integrated laboratory and field experiments with discrete element method (DEM) simulations to investigate soil–residue–machine dynamics across two common tillage practices (disc tillage and subsoiling). A concave disc was used in a controlled soil bin experiment to examine the effects of corn residue length and disc operational angles on soil cutting forces and residue incorporation. Experimental findings showed that longer residue lengths increased both draft force and residue incorporation rate, with the developed DEM model predicting these responses with average relative errors of 9.0% for residue incorporation and 18.2% for draft force. Further, a DEM model simulating soil–cornstalk–disc interactions was established and validated, successfully predicting corn stalk cutting effectiveness and soil cutting forces with an overall relative error of 16.4%. Micro-dynamic analysis revealed that soil bulk density and disc type significantly influenced corn stalk sinkage and soil support forces. In addition to residue cutting studies, the effects of soil heterogeneity defined as vertical spatial variation in soil properties, were explored by developing layered DEM soil models. Simulations of subsoiler performance demonstrated that incorporating heterogeneity improved the prediction accuracy for disturbed soil area, while all models showed acceptable accuracy for predicting soil disturbance width. Finally, the dynamics of wheat residue management with a tandem disc harrow were studied, showing that tillage direction, disc angle, travelling speed, and working depth significantly influenced soil surface roughness, draft force, and soil cutting efficiency. Tillage direction perpendicular to the wheat stubble rows produced lower surface residue cover compared to the tillage direction parallel to the wheat stubble rows. Collectively, these studies contribute to a deeper understanding of soil-residue-machine interactions, offering validated simulation approaches and insights to optimize tillage implement design and operation for enhanced conservation tillage.October 202
Comparing networks of life: cherry picking the path between orchards
No full textPhylogenetic trees have been the traditional model for evolutionary relationships between species, but it has become clear that networks are a better model. Networks add reticulation vertices and edges which can better capture complex evolutionary scenarios such as hybridization and horizontal gene transfer. Network distance, a measure of discrepancy between two networks, is an important problem in the development of the network model as it is often used to validate construction methods. In phylogenetic networks, a cherry describes a structure containing either sibling leaves or leaves whose parents are the endpoints of a reticulation edge. A reduction operation induced on this structure removes the cherry by the deletion of a leaf or a reticulation edge. Cherry reductions have been shown to have algorithmic applications to networks, including determining containment and isomorphism, pointing to sequences of cherry reductions representing some level of similarity between two networks.
With this in mind, we define a novel phylogenetic network distance, design an algorithm that solves for it, and show that it is usable for real network applications. We give a number of equal distance formulations we call "cherry distance". We show that it is NP-hard to calculate, even between a tree and network. Because cherry distance is NP-hard, we likely cannot avoid an exponential runtime to calculate it exactly. We do, however, design an FPT algorithm that runs in time exponential only in the combined number of reticulations in the queried networks. This is made possible by the constraint that 'blobs' remain uncomplicated by having no more than one reticulation each. Finally, we show the efficient operation of software that calculates cherry distance. This new package, CherryRed, implements the algorithm previously designed, and includes a new optimization and a fast heuristic. We furthermore use the software to show some interesting behaviours of cherry distance by comparing it to other distances, in particular we show there is a nice correlation between cherry distance and the number of network leaves downstream from a structural disagreement. In all, the impact of this program of research is in furnishing the computational toolkit available to practitioners in comparative genomics.February 202
Combinatorial Geometry Notes - revised version
No full textThis is a revised, corrected version of Combinatorial Geometry Notes (http://hdl.handle.net/1993/37002). This book contains material for use in Combinatorial Geometry (MATH 4300/7300). As a bonus, a fairly extensive review of elementary Euclidean geometry is given, which can be used in a variety of courses, including contest training. There are 945 references and 371 exercises, most with solutions, and 146 figures. Topics include convex polytopes, geometric graph and Ramsey theory, dissections, lattice theory, colouring finite projective planes, and famous geometric puzzles. Included are reviews of graph theory, number theory, and vector geometry. This book is written in LaTeX, with many diagrams done using Tikz. The .pdf file is cross-linked for ease of use
From earth to art: craft, clay, and cultural continuity across Ethiopia and Indigenous Manitoba
No full textFrom Earth to Art: Craft, Clay, and Cultural Continuity Across Ethiopia and Indigenous Manitoba examines how women’s craft practices with clay and grass embody memory, resilience, and cultural continuity. Through practice-based research, I worked with Winnipeg’s local clay and cattail grass alongside Ethiopian basketry and pottery traditions. My MFA exhibition included woven vessels, ceramic beads, tiles, photographs, and raw materials, creating a multisensory environment. Drawing on feminist and decolonial theory, I argue that craft is not decorative but a powerful tool of knowledge-making, cultural resistance, and storytelling that links land, body, and generational memory.October 202
Yellow-Emitting, Pseudo-Octahedral Zinc Complexes of Benzannulated N^N^O Pincer-Type Ligands
No full textA series of yellow-emitting, pseudo-octahedral Zn(II) complexes supported by monoanionic, tridentate acetylacetone-derived N^N–^O ligands incorporating phenanthridine (benzo[c]quinoline) units is presented. These species emit weakly in solution but exhibit extended millisecond luminescence lifetimes in the solid state at room temperature, and in a frozen glass at 77 K, indicative of phosphorescence from low-lying triplet excited states. Excitation spectra indicate a role for aggregation in enhancing emission in the solid state. In contrast to four-coordinate phenanthridinyl amide-supported tetradentate Zn(II) complexes which are nonemissive in fluid solution, solid-state X-ray crystallographic structures, solution IR spectroscopy, and computational analysis all indicate a delocalized character for the central deprotonated NH which tempers the amido character of the ligand. This design provides a mechanism for “turning on” long-lived luminescence from N-heterocycle/amido-supported Zn(II) coordination compounds
Nonparametric Bayesian classification for fault detection in an electro-hydrostatic actuator
No full textHydraulic actuators are critical components in various industrial applications, and detecting internal leakage is essential for ensuring proper functioning and minimizing downtime. This thesis develops a nonparametric Bayesian framework for classifying leakage levels based on pressure signal data. Two modeling approaches are explored: (1) multinomial logistic regression with Dirichlet Process and Gaussian Process priors applied to extracted signal features from the Variance Fractal Dimension (VFD) method, and (2) the Infinite Hidden Markov Model (IHMM), which directly models temporal dynamics in raw signal sequences. Bayesian inference for the regression-based models is performed using the Metropolis-Hastings MCMC algorithm, while IHMM inference is conducted via collapsed Gibbs sampling. Posterior predictive distributions are used to make leakage-level predictions, and model performance is evaluated through k-fold cross-validation. Hyperparameters in all models are tuned through cross-validation and the performance is evaluated with different classification evaluation
metrics. The nonparametric nature of these models allows them to flexibly adapt model complexity to the data, supporting multi-class classification while capturing uncertainty.October 202
A Julia-based parallel FEM solution to the shallow water equations
No full textThis thesis presents A two-dimensional finite element method (FEM) solver for the
shallow water equations, implemented in the Julia programming language, is presented.
The numerical design of the solver is inspired by the CRISSP2D model,
which was originally written in Fortran decades ago. However, its original codebase
is difficult to maintain and not well suited for modern parallel computing. To
address these limitations, the solver presented in this work is constructed from the
ground up with independent data structures, algorithms, and parallelization strategies.
The implementation solves the depth-averaged shallow water equations using
a Petrov-Galerkin testing method with linear triangular elements and leapfrog time
integration, and it supports dynamic wetting and drying processes. Particular improvements
are made in the treatment of boundary conditions through integration
by parts applied to the weak form of the formulation.October 202
Uncovering interferon lambda responses in human gastrointestinal immunity
No full textType III interferons (IFN-λs) are cytokines that are key players of mucosal immune responses by signalling through a heterodimeric receptor composed of IFN-λ receptor 1 (IFN-λR1) and IL-10RB. Unlike type I IFNs, which primarily act on immune cells in the gut, IFN-λs especially act on epithelial cells due to the selective gene expression of IFNLR1. While murine models have demonstrated protective roles for IFN-λ in colitis, including promoting epithelial repair and modulating immune responses, species-specific differences and limitations of acute inflammation models hinder translation to human ulcerative colitis (UC).
To address this gap, we used recently screened new monoclonal antibodies for the detection of IFN-λR1 by flow cytometry and immunofluorescence on human immune cells and intestinal tissue. Using these tools alongside qPCR, we quantified IFN-λR1 protein and transcript levels in terminal ileum (TI) and sigmoid (Sig) colon biopsies from UC remission and non-UC (control) donors. In my initial analyses, IFNLR1 expression and IFN-λR1 protein level were found to be comparable across tissue sites and disease states, although further analyses are needed at the single-cell level.
Ex vivo stimulation of non-UC biopsies with IFN-λ3 revealed region-specific bulk transcriptional responses. IFN-λ3 addition to TI biopsies led to an upregulation of some pro-inflammatory genes (e.g., IL17F, IL23A) compared to untreated samples. In contrast, IFN-λ3-stimulated Sig biopsies instead were characterized by especially an upregulation of IFN-stimulated genes (e.g., IFIT1, MX1). Further pathway analyses suggested that IFN-λ3 may have differentially affected JAK/STAT signalling outputs when comparing TI and Sig biopsies. When I next compared IFN-λ3-induced transcript changes between non-UC to UC remission samples, IFN-λ-induced MX1 and IFIT1 levels showed a downward trend in UC remission Sig biopsies, suggesting possible attenuation of IFN-λ responsiveness even during remission.
Overall, this work has significantly improved multiple techniques for the detection of human IFN-λR1, especially at the protein level. I have also used a novel biopsy culture assay to identify potential spatial and disease-specific differences in IFN-λ responses in the human gut. It is clear that type III IFNs are more than antivirals in the gut, but my work starts to uncover specific IFN-λ-regulated transcriptome changes in human gut tissue and whether type III IFN activity could be altered in UC.Canadian Institutes of Health Research
Rady Faculty of Health Sciences
Research ManitobaOctober 202