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Developing an Automated System to Measure Player Velocity for Head Impacts Evaluation using 2D Video in Youth Ice Hockey Games
No full textTraumatic brain injury (TBI) is a major concern in contact and collision sports such as football, rugby, ice hockey, and boxing, where athletes are frequently subjected to repetitive head impacts. These impacts range from mild concussions to severe neurological trauma and are often associated with long-term cognitive, behavioural, psychological, and physical impairments. In ice hockey, the combination of high-speed skating and physical contact significantly increases the risk of concussion. Concussion rates as high as 1.81 per 1000 athletic exposures have been reported, emphasizing the need for improved injury monitoring and prevention, particularly at the youth level, which constitutes the majority of participants in the sport. Young athletes are especially vulnerable due to their developmental stage and lack of access to monitoring technologies commonly available in professional settings. Many head impacts in youth hockey go undetected or unreported, impeding early intervention and increasing the risk of long-term effects. Effective injury mitigation requires a deeper understanding of the biomechanical factors contributing to brain trauma, including impact magnitude, frequency, inter-impact intervals, and cumulative exposure duration. Among these, velocity at the moment of impact plays an important role in determining the kinematics and energy transferred to the brain. However, the relationship between specific impact characteristics and clinical outcomes remains poorly understood. Developing predictive models requires large, structured datasets that capture biomechanical and contextual variables in real-world game settings. To address this need, and as part of a larger project aimed at developing a fully automated pipeline to extract head-impact characteristics from 2D video, this study focused on a primary step required for estimating head-impact velocity. Specifically, we developed and validated a fully automated pipeline for estimating planar player velocity using single-camera, side-view 2D video footage, an accessible and scalable solution tailored to youth hockey environments. The pipeline eliminates the need for specialized tracking systems and consists of three core components, structured into three studies:
Study 1: Object Detection for Ice Surface Localization in Youth Hockey
A YOLOv5 object detector was trained on 9,900 annotated side-view frames from youth games at the Peewee, Midget, and Atom levels to identify specific rink landmarks. When at least four landmarks were detected by the network, a custom script computed a homography matrix to project the side-view frame into a standardized top-down view. This approach demonstrated strong performance, achieving an F1 score of 0.99 and [email protected] of 98.5% for object detection, along with an average Intersection over Union (IOU) of 0.96 for localization accuracy.
Study 2: Development of an Automated System to Obtain the Planar Velocity of Individual Players From 2D Video of Youth Ice Hockey Games
A YOLOv8 model, pretrained on 80,000 NHL images and fine-tuned on 4,700 youth hockey frames, detects and classifies players by jersey color (light/dark). Player tracking is performed using a modified StrongSORT algorithm, which reduced identity switch errors from 172 to 53 on 100 clips and improved Multi-Object Tracking Accuracy (MOTA) from 89.0% to 94.5%. Trajectories are transformed into top-down coordinates using the output of Study 1, and velocity is estimated based on displacement over 5-frame intervals (200 ms at 25 FPS), enabling real-time analysis of motion patterns relevant to head impact risk. A YOLOv8 model, pretrained on 80,000 annotated NHL player images and fine-tuned on 4,700 annotated youth hockey frames, was used to detect and classify players by jersey color (light/dark). The model achieved high detection accuracy, with a precision of 96% and a recall of 97%. Player tracking was performed using the StrongSORT algorithm enhanced with our custom cost function, which reduced identity switch errors from 172 to 53 across 100 clips (90 frames each at 30 FPS) and improved Multi-Object Tracking Accuracy (MOTA) from 89.0% to 94.5%. Player trajectories from side-view footage were transformed to a top-down view using frame-by-frame homography calculated in Study 1, and velocities were estimated based on displacement over 5-frame intervals (200 ms at 25 FPS).
Study 3: Validation of Deep Learning-Based Velocity Estimation from Single, Side-View Ice Hockey Game Footage Using Top-Down Drone Measurements
The objective of Study 3 was to validate the player velocities estimated by the proposed pipeline in Study 2 under real-world conditions, using drone-mounted top-down video as the ground truth. Velocities in the top-down footage were manually extracted in Kinovea by tracking a helmet-mounted marker across synchronized 10-frame intervals. Side-view estimates from both fixed and panning camera configurations were compared against the ground truth across four rink regions: two defensive faceoff circles and two central zones (near and far from the camera). Movement types included lateral, forward, and diagonal skating paths. A zoomed-in side camera configuration was also tested in the far zone to assess the impact of reduced landmark visibility. Results showed that both fixed and panning camera setups achieved mean absolute errors under 10%, while the zoomed-in configuration remained within 20%, a range still acceptable for categorizing impact severity. Bland–Altman analysis indicated strong agreement between the fixed/panning configurations and the top-down reference, providing preliminary validation of the pipeline. Sensitivity analyses were conducted by perturbing player coordinates in both axes by ±5, ±10, and ±15 pixels to evaluate susceptibility to localization error. The results revealed greater sensitivity in regions farther from the camera. Additionally, velocity was recalculated using temporal windows of 5, 10, 20, and 30 frames, showing that increasing the frame window consistently reduced error, particularly in the vertical direction where perspective distortion is more pronounced.
This study proposed a preliminarily validated pipeline offering a cost-efficient, scalable, and accessible solution for estimating player velocity from standard broadcast footage of youth ice hockey games. Its fully automated structure and reliance on commonly available video make it particularly suited for large-scale injury surveillance and biomechanics research in environments without advanced tracking infrastructure or specialized sensor-based systems. As part of a larger project to develop an automated data capture system for documenting head impact characteristics, this study focused on creating and validating an AI-driven method for estimating player velocity in the context of head impacts. Velocity is a key factor influencing the energy transferred to the head during collisions. By generating large datasets and applying advanced AI algorithms, the system enables the identification of patterns linking impact characteristics to injury outcomes
Sexually dimorphic response to tobacco exposure in COPD: a systematic review and meta-analysis
No full textAbstract Background Chronic obstructive pulmonary disease (COPD) is a heterogeneous, progressive pulmonary disorder with persistent respiratory symptoms resulting from abnormalities in the airways and/or alveoli and was prevalent globally in 10.3% of people aged 30–79 years in 2019. The prevalence of COPD has increased rapidly in women in the past decade. This may be due to increased tobacco use, but may also involve sex-specific factors. Purpose To evaluate the prevalence of COPD in the context of sex and tobacco exposure. Data sources and searches Comprehensive searches of MEDLINE (OVID), EMBASE and CENTRAL were conducted for articles published from inception to July 22, 2022. Study selection We independently evaluated titles, abstracts and full-text articles in a duplicated two-staged process. Studies were included if they reported the prevalence of COPD as a primary outcome in the context of sex and tobacco exposure. Data synthesis and analysis Pooled analysis was conducted with Review Manager 5, and heterogeneity was assessed with the I2 statistic. For 163, 450 individuals the prevalence of COPD was 3.5–20.7% in males and 6.3–18.5% in females, and we observed a non-statistically significant difference of 1.53% [95% CI: -5.83, 8.89] (p = 0.68) in females compared to males with tobacco exposure (Tau2 = 54.02; Chi2 = 53.15; df = 4 (P < 0.00001); I2 = 92%). Females with COPD had earlier mortality, greater co-morbidities involving cardiovascular disease and others, and decreased FEV1% predicted, as compared to males with COPD. Estrogen and androgens may protect against COPD, but smoking-induced hypogonadism may diminish these effects. Menopause could also be a contributor to worse COPD outcomes. Limitations Included articles are limited by the quality of data on tobacco smoke exposure, primarily reported as a binary risk factor, with lack of availability on duration and intensity of exposure. Conclusion There was earlier mortality and reduced FEV1 in females with COPD, as compared to males with COPD. Thus, sex-specific considerations are important in understanding the pathophysiology of COPD and should be a focus of further research
The Effects of Online Nudging on Individuals' Behaviour: The Case of Pokémon Go
No full textThe use of nudging in online advertising to subtly align the offering of products and services with individuals' identity is a now commonplace practice. Cheney-Lippold (2017) and Zuboff (2019) criticize online nudging for operating behind closed doors, cycling through of user data and personal information to modify individuals' behaviour for commercial gain. Nudging is a central feature of the popular game Pokémon Go. It uses predictive algorithms and players' geolocational data to create augmented reality gaming scenarios that guide users through real-world public and private spaces as they seek to achieve game-related objectives. As such, Pokémon Go offers an ideal microcosm for analyzing users' awareness of online nudging and other behavioural modification techniques employed in online advertising. Using a qualitative research design, semi-structured interviews were conducted with 23 undergraduate students from the University of Ottawa who self-identify as regular players of Pokémon Go to examine how they understand, navigate, and respond to the nudging practices employed in the game. The observations emerging from an analysis of their descriptions of typical gameplay sessions offer an empirical basis, albeit of limited strength, for challenging assertations that nudging practices are foremost manipulative, exploitative, or somehow disempowering. Likewise, the emerging observations about the diverse ways in which individuals interpret their encounters with nudging practices suggest possible grounds for reimagining how the understanding of data literacy might be approached
Meanings of Diversity in the Chronicle of Higher Education, 2019–25: A Hermeneutic Text Mining Approach
No full textIn the past decade, few policies have been politicized in U.S. higher education as much as those meant to encourage diversity among students and professors. DEI (diversity, equity, and inclusion) policies have become a favourite target among politicians appealing to voters who see them as a symptom of a zero-sum game where people not perceived as “diverse” are valued less than others. This article examines 118 articles about diversity published in the Chronicle of Higher Education between 2019 and 2025. It uses text mining tools (specifically, sentiment, correspondence, and correlation analysis) to map changes in the ways the words related to diversity, in particular DEI and woke, were used. It then employs hermeneutic techniques, drawing on the work of Paul Ricoeur, to interpret the patterns identified through text mining. It shows points of continuity, resulting from the ways speakers respond to past discourse, and change, resulting from the ways they anticipate others’ responses and change their behaviour accordingly. Ultimately, this article documents an evolution in meanings of diversity characterized by growing pessimism in response to national and international politics and conflict
Righteously Entertaining: Punishing and Constructing Society's Moral Reality with Online Public Shamings
No full textOnline public shamings are a contemporary phenomenon in which someone's wrongdoing is publicized online, attracting the attention of a mass audience, which reacts to it, shaming the person and pressuring employers and business partners to cut ties with the culprit. Trying to avoid prejudgements on the phenomenon's ethics, this thesis explores how online public shamings develop. The investigation starts by defining the phenomenon based on five empirical cases and on the existing literature. Based on this definition and initial characteristics, two other similar phenomena were approached from a theoretical perspective, in search of a comprehensive lens for the online public shamings: moral crusades and charivaris. Based on these two phenomena, online public shamings were conceptualized as movements of deviance creation, in which online imagined communities battle to extend their rules and values to opposing publics, and at the same time they punish an individual for breaking a cherished value. By using mixed methods to analyse Twitter data, a single case study was developed. The empirical analysis revealed that online shamers are composed of several different groups, with different types of interests, both opportunistic and righteous. In the latter group, Black Twitter revealed itself as morally engaged with expanding anti-racist rules in American society. The punishment of the shamed, in this sense, represents another episode in a larger movement for social equality in America. The process of deviance creation, nonetheless, is marked by the use of punishment as entertainment and the imposition of rules and consequences without any democratic due process. Even though more research is needed to expand the conclusions of this work, this case study provides an initial framework for the development of basic aspects of online public shamings
Development of Aptamer-Based Biolayer Interferometry Biosensors for the Detection of Cancer and Viral Biomarkers
No full textThis thesis used Biolayer Interferometry (BLI) and DNA aptamers to develop simple and reliable biosensors for detecting important biological targets, including proteins, cancer-derived exosomes, and viral-like particles (VLPs), ranked from simple to complex biomolecules. Aptamers are short single-stranded DNA molecules that can be considered as a bio recognition element that are able to specifically recognize proteins or particles, similar to antibodies but with better stability and easier preparation. This study sought to develop a rapid, sensitive, and label-free technology for quantitative detection by integrating aptamers with the BLI method, which enables real-time monitoring of molecular interactions without the need for labels. In the first project, an aptamer designed for the Ki-67 protein, a known marker of cell proliferation, was studied using a BLI platform. The results showed a strong and preferable specific interaction between the aptamer and Ki-67 protein, with a dissociation constant (KD) of 10.9 ± 0.6 nM and a clear linear relationship across the working range of 50-400 nM. This confirmed that the BLI-based aptasensor can provide accurate and reproducible data for protein detection. The second project focused on the detection of cancer-derived exosomes from MDA-MB-231 cells using three known aptamers: CD63, MUC1, and 5TR1. Exosomes were isolated through a gold standard isolation method which is ultracentrifugation and characterized by Dynamic Light Scattering (DLS) and Transmission Electron Microscopy (TEM), which confirmed their typical size and structure. The binding tests showed that all three aptamers interacted strongly with exosomes, with KD values in the picomolar range and good linearity in the calibration plots. These results demonstrated the high sensitivity and specificity of the aptamer-based BLI system for exosome analysis. In the third project, newly selected aptamers were tested for recognizing SARS-CoV-2 pseudoviruses (VLPs). Among them, the S1-SP10 aptamer showed the best performance with a KD of 112 ± 5 nM and a limit of detection (LOD) of 33 nM. The assay showed clear dose-dependent signals and high specificity compared to the scrambled control sequence, confirming that the aptamer could effectively bind the viral spike protein in its native form.
Overall, this research shows that BLI combined with aptamers is a powerful and flexible approach for studying molecular interactions and detecting disease-related biomarkers. The developed aptasensors worked well for different biological systems, proteins, exosomes, and viral particles, proving their potential for future use in medical diagnostics and real-sample testing
Assessing the Impact of Collection, Production, and Storage of Platelet Concentrates on Bacterial Contamination and Product Safety
No full textThe bacterial contamination of platelet concentrates (PCs) poses a safety risk to transfusion patients. Despite the implementation of mitigation strategies like donor skin disinfection and bacterial screening of PCs using culture methods, the anaerobic, slow growing bacterial contaminant Cutibacterium acnes is frequently transfused into patients. Fortunately, since this bacterium is incapable of proliferating in the aerobic PC storage environment, it has only been associated with mild adverse reactions. However, very little is known about the long-term impact of these transfusion events. This is particularly pertinent, since C. acnes is known to harbor a host of virulence factors that it can harness to cause slow developing, chronic infections, and the PC environment has been demonstrated to elicit the enhanced expression of virulence genes in other transfusion relevant bacteria. Furthermore, certain non-infectious transfusion reactions are driven by proinflammatory factors that accumulate in PCs during storage, and interestingly, bacterial interactions with platelets can elicit the release of these factors. It is therefore important to elucidate whether the transfusion of C. acnes contaminated PCs enhances the risk of such non-infectious adverse reactions.
My thesis aims to elucidate the role that C. acnes contamination plays in the PC manufacturing process from blood collection to storage, and its impact on blood product safety. To that end, I hypothesized that C. acnes evades elimination during skin disinfection, contributing to its dominance as a bacterial contaminant of PCs. I further hypothesized that the virulence of C. acnes is heightened in the PC storage environment and C. acnes contamination results in an enhanced pro-inflammatory profile of PCs. The four objectives designed to test the hypotheses were to 1) investigate the ability of C. acnes to resist eradication by donor skin disinfectants, 2) enhance C. acnes detection through supplementation of culture media, 3) determine whether the PC storage environment enhances the virulence of C. acnes, and 4) evaluate whether PCs contaminated with C. acnes have an elevated pro-inflammatory profile. The data obtained in this study demonstrated that sebum components dampen the efficacy of the current blood donor skin disinfectant against C. acnes and may contribute to its dominance as a PC contaminant. I have also shown that the use of a commercially available supplement can reduce the detection time of C. acnes during PC screening with culture methods, the use of which has the potential to prevent the transfusion of C. acnes contaminated PCs. Furthermore, my data indicated that antigen shielding in PC derived C. acnes samples may reduce the acute immune response in a novel silkworm model, thereby dampening the virulence observed. However, the ability of C. acnes to adhere to mammalian epithelial cells and the expression of virulence genes involved in tissue invasion and persistence are enhanced in PCs, suggesting that the potential to cause chronic infections by C. acnes is augmented in this environment. Finally, I demonstrated that C. acnes contamination does not enhance the pro-inflammatory profile of PCs and therefore does not increase the risk of non-infectious adverse reactions.
The research presented in this thesis has helped identify areas of improvement in the blood collection process and provided evidence for the use of supplements to enhance culture based bacterial screening for C. acnes. Notably, my work fills a void in our current understanding of the potential risks involved in transfusing C. acnes contaminated PCs. In conclusion, I have contributed to the advancement of knowledge in the field of transfusion medicine and provided insight into enhancing the safety of transfusion patients
Realities of Precarity in Canada's Seasonal Fields: Struggles, Advocacy, and Restricted Spaces and Voices
No full textThe following thesis examines the complex reality of temporary migration within Canada's agricultural sector by investigating the Seasonal Agricultural Worker Program (SAWP). The relevance of this inquiry hosts far-reaching implications for not only the wellbeing of migrant workers, but for the Canadian food-system, as well as migrant sending states. Furthermore, this research contributes additional knowledge and insights regarding the evolving interconnections between the climate and migration crisis that host critical impacts for Canada and the world moreover. In analyzing the impact of the SAWP on migrant workers' lives through two case studies, the project explores the interplay between climate change, globalization, neoliberalism, and liberalization in shaping the precarity faced by migrant workers in Canada. Despite the commonly advertised benefits of the SAWP, the study finds that structural barriers and power imbalances limit the realization of these benefits for migrant workers. The study ultimately explores the divided calls for reform across the sector, revealing the influence of widespread industry malpractice, and the presence of entrenched power hierarchies that have served to dominate the scope and direction of change. The research finds that the SAWP's structure and the broader context of inequalities related to globalization and neoliberalism hinder migrant workers' ability to leverage their assets and improve their livelihoods in Canada
Cortical Reorganization and Sensorimotor Recovery in a Mouse Model of Intracerebral Hemorrhagic Stroke
No full textIntracerebral haemorrhage (ICH) is a subtype of stroke that accounts for approximately 10-15% of stroke cases in Canada. Neurological deficits following ICH are common and most patients will suffer long-term impairments. Spontaneous recovery facilitated by the remodeling of functional areas through neuronal reorganization has been observed in both stroke patients and animal models. However, the precise relationship between cortical remodeling and functional recovery is not completely understood. This thesis aims to characterize the reorganization of the sensorimotor cortex as well as quantify sensorimotor function longitudinally during the recovery period. Young Thy1-Chr2-YFP mice with an implanted chronic window over the intact skull allowed visualization of sensorimotor cortex functional assessments through light-based motor mapping and intrinsic signal optical imaging over a 6-week period. Additionally, a battery of behavioral tests was conducted in parallel to evaluate motor deficits. Following a striatal ICH, behavioral impairments were observed with both acute and chronic recovery. The deficits shown in ICH mice were linked with a disruption of motor maps. When stimulating the injured hemisphere, evoked movement of both forelimbs
showed smaller amplitude compared to sham animals, which was accompanied with a reduction in the motor map size. On the other side, the contralesional hemisphere did not show any differences compared to the sham animals, demonstrating a potential compensatory mechanism. A trend toward recovery in the motor maps occurred on the 6th week, matching the late recovery of impaired forelimb use deficit. Conversely, the sensory responses evoked from mechanical forelimb stimulation did not show any changes following ICH induction. This is the first study to investigate the longitudinal impact of striatal ICH on bilateral sensorimotor maps in relation to behavioral deficits. Our findings revealed that injury in the striatum leads to long-term functional impact in the motor cortex accompanied by behavioral motor deficits, with a recovery of motor functions matching the recovery initiation in motor representations
Pro-Atherogenic Macrophages Induce Upregulation of MLKL and Cell Death in Vascular Smooth Muscle Cells During Atherogenic Stimulation
No full textBackground: A hallmark of advanced, rupture-prone atherosclerotic lesions is the presence of a necrotic core – a dense mass of pro-inflammatory and cellular debris. Traditionally, it has been thought that most of the foam cells within this core are derived from macrophages. However, recent advances in single cell technologies have revealed that vascular smooth muscle cells have the capacity to transdifferentiate into “macrophage-like foam cells”, accounting for almost half of the cell content in advanced plaques. Our lab and others have discovered that a primary cause of the necrotic core is necroptotic cell death, where the mixed lineage kinase domain like pseudokinase MLKL is a key executioner of this process. While the contribution of necroptosis in macrophages and macrophage-derived foam cells to plaque growth and instability has been fairly-well studied, the role of necroptosis in vascular smooth muscle cells in this process remains unclear.
Objective: This work explores the role of MLKL in regulating necroptosis of macrophages and vascular smooth muscle cells when challenged with pro-inflammatory and pro-atherogenic stimuli.
Hypothesis: MLKL regulates cell death differently in macrophages and vascular smooth muscle cells when challenged with pro-inflammatory or pro-atherogenic stimuli.
Methods and Results: Bone marrow-derived macrophages (BMDMs) and aortic vascular smooth muscle cells (VSMCs) were isolated from wildtype and MLKL-/- mice and treated with pro-atherogenic stimuli in the presence or absence of apoptosis and necroptosis inhibitors, zVAD and Necrostatin-1 (Nec1). BMDMs underwent cell death in response to treatment within 3-6 hours (as measured by LDH release and SYTOX assays), while VSMCs survive up to 18-24 hours. However, when treated with BMDM conditioned media, VSMCs begin to show higher rates of relative cell death compared to controls, particularly in response to treatment with oxLDL. Confocal microscopy and Western blots revealed that VSMCs treated with oxLDL in addition to BMDM conditioned media show an increase in relative expression of total and phosphorylated-MLKL – a key hallmark of necroptosis – compared to VSMCs without conditioned media. Moreover, these experiments implicate STAT1 and IRF1 as possible transcriptional regulators of MLKL expression in VSMCs treated in BMDM conditioned media. Preliminary staining of atherosclerotic lesions in mice may suggest that MLKL expression is more abundant within macrophages, and upregulation of MLKL expression in VSMCs may be associated with phenotypic switching.
Conclusion: Overall, this work suggests VSMCs are inherently resistant to necroptosis, unless treated with conditioned media from BMDMs, which may suggest that macrophages have the capacity to prime necroptosis in VSMCs, likely through secreted factors