19614 research outputs found
Sort by
Predictive modelling, Anomaly Detection, and Empirical Extraction of Variation Patterns within Longitudinal Data
Get PDFThis dissertation represents a comprehensive exploration and enhancement of statistical methodologies, addressing complex challenges in transdisciplinary data analysis. It integrates novel techniques across various domains to bridge gaps in existing algorithms, focusing on advancing multitask prediction and anomaly detection. Significant contributions involve extended stacking algorithms for survival and longitudinal data prediction, an innovative unsupervised learning algorithm for real-time spectral anomaly identification and classification, and applications of longitudinal data analytics in multi-decade geospatial marine pollution monitoring data, including paralytic and amnesic shellfish toxins and fecal coliform bacteria. This dissertation emphasizes the collective contributions of these interconnected research findings, aiming to advance predictive modelling methodologies and anomaly detection across disciplines.Graduat
Arctic Politics in a Time of Change: A Study on the Impact of Deteriorating Relations on the Indigenous Peoples’ Inclusion in Arctic Decision-Making Processes
Get PDFThis thesis examines how the deterioration of Arctic politics since 2007, led by a changed geopolitical perception of the Arctic region and worsened relations between Russia and the West, has impacted the Indigenous Permanent Participants’ abilities to advance their own interests in Arctic governance. Through a textual analysis of research on Arctic politics and security, a discourse analysis of the Saami Council and the Inuit Circumpolar Council’s response to the Arctic Council’s suspension in 2022, and analysis of the Arctic Council’s structure and an examination of the Russian-West relations between 2007-2022, I argue that the deterioration in Arctic politics affects the Permanent Participants’ abilities to advance their interests in Arctic governance in two ways. First, it has increased state-centric decision-making in the Arctic Council, which largely leaves out the Permanent Participants from the Council’s decision-making processes. Second, it has increased the workload in the Council, which has heightened the Permanent Participants’ demand for funding in order to participate. I conclude that continued deterioration in Arctic relations will negatively affect Arctic Indigenous peoples, as they continue to remain constrained within their national contexts and other international institutions in regard to advancing their own priorities. Through the theoretical lens of securitization and ‘acts of indigeneity’, this study contributes to the understanding of how the Arctic Indigenous peoples strategically aim to situate themselves as political beings in the Arctic decision-making processes in response to the current deterioration in Arctic politics.Graduat
Loss of Dna2 fidelity results in decreased Exo1-mediated resection at DNA double-strand breaks
Get PDFWe thank Lorraine Symington for generously providing us with the plasmid overexpressing EXO1, pEM-EXO1.A DNA double-strand break (DSB) is one of the most dangerous types of DNA damage that is repaired largely by homologous recombination or nonhomologous end-joining (NHEJ). The interplay of repair factors at the break directs which pathway is used, and a subset of these factors also function in more mutagenic alternative (alt) repair pathways. Resection is a key event in repair pathway choice and extensive resection, which is a hallmark of homologous recombination, and it is mediated by two nucleases, Exo1 and Dna2. We observed differences in resection and repair outcomes in cells harboring nuclease-dead dna2-1 compared with dna2Δ pif1-m2 that could be attributed to the level of Exo1 recovered at DSBs. Cells harboring dna2-1 showed reduced Exo1 localization, increased NHEJ, and a greater resection defect compared with cells where DNA2 was deleted. Both the resection defect and the increased rate of NHEJ in dna2-1 mutants were reversed upon deletion of KU70 or ectopic expression of Exo1. By contrast, when DNA2 was deleted, Exo1 and Ku70 recovery levels did not change; however, Nej1 increased as did the frequency of alt-end joining/microhomology-mediated end-joining repair. Our findings demonstrate that decreased Exo1 at DSBs contributed to the resection defect in cells expressing inactive Dna2 and highlight the complexity of understanding how functionally redundant factors are regulated in vivo to promote genome stability.This work was supported by operating grants from Canadian Institutes of Health Research (grant nos.: MOP-82736 and MOP-137062) and Natural Sciences and Engineering Research Council of Canada (grant no.: 418122) awarded to J. A. C.FacultyReviewe
Adaptive resource allocation in multi-agent social networks
Get PDFDistributing resources among agents in social networks is an important and challenging problem. It involves deciding on assignment of a subset of resources to each agent based on the system objectives. Various instances of this problem can be observed in healthcare resource distribution, disaster management, cloud resource optimization, etc. In collaborative systems, different coordination techniques have been introduced in order to maximize overall social welfare. However, this problem becomes more complex in large-scale networks with limited connectivity among the agents. Moreover, in dynamic environments, where the set of tasks or resources change over time, an effective system needs to adapt to changes in the environment. Existing mechanisms fall short in addressing the social network constraints, and do not present efficient solutions when dealing with dynamic changes of supply and demand quantities. In this thesis, we view this social resource allocation problem (SRAP) as a multi-agent coordination problem. In a centralized approach, we consider a master agent with global knowledge, which makes decisions for all the agents. We present a greedy mechanism using an efficiency heuristic, and a learning-based mechanism by formulating the SRAP as a Markov Decision Process (MDP), and incorporating deep Q-learning. On the other hand, in a decentralized approach, we present a multi-agent protocol, which relies on local interactions among agents and their local knowledge only. The protocol enables the agents to negotiate with each other on allocation of resources to their tasks. It allows an agent in need of resources to concurrently negotiate with multiple providers and combine their resource contributions. We present greedy and learning-based mechanisms by integrating deep Q-learning into the negotiation process. In addition, the agents are able to cascade their corresponding information along the network, and apply timeouts in their messages. Hence, the decentralized protocol enables the multi-agent system to be self-organized, without relying on any central entity. We evaluate our approaches by developing simulation models of agents, tasks, and resources. We perform experiments on three main types of social networks, namely small-world, scale-free, and random networks. We conduct an empirical study of the performance of these approaches under varying conditions, such as resource availability, resource types, task requirements, etc. Our simulation results present a comprehensive analysis of various approaches across different types of social networks, by highlighting the strengths and limitations of centralized versus decentralized, as well as greedy versus learning-based approaches.Graduat
Formal Algebraic Reasoning About Compression Function Security
Get PDFCryptographic hash functions are fundamental in cryptographic constructions, as
they transform variable-length input into fixed-length output while maintaining essential security properties like collision resistance, preimage resistance, and indifferentiability from a random oracle (RO). Creating efficient hash functions with provable
security has long posed a challenge. Security proofs for hash functions usually fall
under the random oracle model or the ideal cipher model, which assumes access to
an ideal primitive like a truly random function or permutations.
This research endeavors to establish a systematic approach for analyzing the security of hash functions suitable for automated verification and function generation
within both ideal models. Building upon prior work [25], which employed an algebraic framework known as Linicrypt[8], primarily for analyzing collision-resistant hash
functions in the random oracle model, we extend our efforts in two key directions.
We first introduce a simple and easily verifiable property of Linicrypt programs
that characterizes preimage awareness, a security property introduced by Dodis, Ristenpart, and Shrimpton [13] who also demonstrate its utility in the construction
of indifferentiable hash functions. We also illustrate how this characterization can
be efficiently automated and provide an example by enumerating preimage-aware
compression functions that employ two random oracle calls. This includes several
functions that Dodis et al. previously proved to be preimage aware through manual
methods.
Next, we broaden the Linicrypt framework, originally proposed in the random
oracle setting, to encompass hash function security in the ideal cipher model. Within
this context, we delineate collision- and second-preimage-resistance properties using
linear-algebraic conditions on Linicrypt programs. We also introduce an efficient algorithm for determining program compliance with these conditions. As an application,
we delve into the case of block cipher-based hash functions as proposed by Preneel,
Govaerts, and Vandewall [32] and establish that our characterization encapsulates the
semantic analysis of PGV presented by Black et al.[5].
Additionally, our research further extends into the ideal cipher model to analyze group-2 compression functions, a category introduced in the well-known work[4].
These are compression functions which are not collision-resistant themselves, but pro-
duce collision-resistant hash functions when iterated by the Merkle-Damgard trans-
formation. We also provide a comprehensive characterization of collision-resistant
double block length compression functions within the ideal cipher model.Graduat
Participatory system mapping for food systems: Lessons learned from a case study of Comox Valley, Canada
No full textFood systems are complex and multifaceted, comprising a diverse range of actors, processes, and interactions. Participatory system mapping can be employed to help understand this complexity and support the development of sustainable and resilient food systems. This article shares a participatory mapping approach that has been developed as part of the Climate–Biodiversity–Health (CBH) Nexus project in the Comox Valley, British Columbia, Canada. This research pursues two main aims: (1) to ground truth in the CBH system map of food systems, developed with the participation of stakeholders; and (2) to explain how participatory system mapping can be employed to clarify the complexity of food systems in a clear and concise manner for all stakeholders. This research contributes to the literature on participatory system mapping, including critiques of its practical utility, by employing participatory approaches to visualize multi-dimensional and multi-level system maps with an emphasis on verifying that they are clear, understandable/useful, and reliable for diverse stakeholder audiences.This research was funded by the Social Sciences and Humanities Research Council (SSHRC) of Canada’s Insight Grant Program (Grant File Number: 435-2021-0708).FacultyReviewe
Experimental Investigation into the Behavior of Geocell-Reinforced Bases under Freeze-Thaw Cycles
No full textFreeze-thaw (F-T) cycles significantly contribute to the deterioration of roadways in seasonal frost regions. Among various countermeasures to mitigate F-T damages, the application of geocells for base stabilization has demonstrated its effectiveness in enhancing the F-T performance of road bases due to their three-dimensional stiffening and reinforcing effects. Despite the practical success of the use of geocells in base stabilization, a scarcity of research has focused on qualitative or quantitative evaluation on the benefits of geocells in improving the F-T performance of bases.
To address this research gap and assess the F-T performance of geocell-stabilized bases, this study conducted a series of laboratory element and model tests as well as full-scale field tests. This study first introduced the development of a customized model test apparatus capable of performing unidirectional F-T tests and plate loading tests on the geosynthetics-stabilized bases in Chapter 1. Utilizing this apparatus, influencing factors of fines content (Chapter 2), water supply and compaction degree (Chapter 3) were investigated directly. Furthermore, the F-T effect on the mechanical behavior of geocell-stabilized soils was explored through elements tests, serving as a complement to the comprehensive assessment (Chapter 4).
A significant portion of this study involved comprehensive full-scale field tests that comparatively investigated the efficacy of applying geocells and geogrid composites in a flexible pavement in Alberta, Canada. This comparison was made across three test sections stabilized with two types of Novel Polymeric Alloy (NPA) geocells and a geocomposite. A full instrumentation program with the design and installation of different sensors such as earth pressure cells, thermocouples, and moisture sensors was introduced in Chapter 5. Short-term testing and long-term monitoring were implemented. Short-term tests included plate loading tests and trafficking tests before and after the first seasonal F-T cycles, while the long-term monitoring focused a 12-month monitoring of soil temperatures, moisture contents and loads transferred to the subbases after open to general traffic (Chapter 6).
The results of the experimental tests including element and model tests was field investigations significantly contributed to the understanding of the effectiveness of geocell stabilization in mitigating F-T induced damages, providing insights into the underlying stabilization mechanisms.Graduate2025-05-0
Smartphone enabled biomarker sensing and on-demand drug delivery using 3D printed hollow microneedle arrays
No full textRemote health monitoring and disease treatment are pivotal in advancing health equity, reducing geographical and socioeconomic barriers, and providing universal access to quality care. By enabling continuous, personalized healthcare, this paradigm addresses disparities, offering timely interventions for individuals in underserved or remote locations. Microneedle arrays (MNAs) stand at the forefront of this revolution, enabling painless, minimally invasive access to interstitial fluid for both diagnostics and drug delivery.
This paper presents a groundbreaking theranostic wearable system, leveraging digital light processing (DLP) 3D-printed hollow microneedle arrays fabricated using PEGDA hydrogel, equipped with colorimetric sensors for the quantitative analysis of key biomarkers, including pH, glucose, and lactate, directly from the skin's interstitial fluid. The system incorporates a remotely activated, smartphone enabled, ultrasonic atomizer-driven mechanism for on-demand drug delivery, enhancing portability by eliminating the need for complex mechanical pumps. This integrated approach simplifies point-of-care treatments and expands the possibilities for remote patient management.
The accompanying smartphone application seamlessly interfaces with the system, enabling real-time monitoring and drug administration. Demonstrated results include precise detection of pH (3–8 mM), glucose (up to 16 mM), and lactate (up to 1.6 mM), as well as enabling the effective administration of drugs in response to biomarker fluctuations. The system's drug delivery performance was validated using on-demand on/off tests and its biocompatibility using a scratch assay, highlighting its potential for treating chronic diseases requiring sustained therapy.
This innovative platform not only addresses key challenges in drug delivery but also opens new pathways for non-invasive health monitoring, offering a transformative solution for the long-term management of chronic conditions.Graduat
Exploring electrophilic hydrophosphination via metal phosphenium intermediates
No full textTwo Mo(0) phosphenium complexes containing ancillary secondary phosphine ligands have been investigated with respect to their ability to participate in electrophilic addition at unsaturated substrates and subsequent P−H hydride transfer to “quench” the resulting carbocations. These studies provide stoichiometric “proof of concept” for a proposed new metal-catalyzed electrophilic hydrophosphination mechanism. The more strongly Lewis acidic phosphenium complex, [Mo(CO)4(PR2H)(PR2)]+ (R=Ph, Tolp), cleanly hydrophosphinates 1,1-diphenylethylene, benzophenone, and ethylene, while other substrates react rapidly to give products resulting from competing electrophilic processes. A less Lewis acidic complex, [Mo(CO)3(PR2H)2(PR2)]+, generally reacts more slowly but participates in clean hydrophosphination of a wider range of unsaturated substrates, including styrene, indene, 1-hexene, and cyclohexanone, in addition to 1,1-diphenylethylene, benzophenone, and ethylene. Mechanistic studies are described, including stoichiometric control reactions and computational and kinetic analyses, which probe whether the observed P−H addition actually does occur by the proposed electrophilic mechanism, and whether hydridic P−H transfer in this system is intra- or intermolecular. Preliminary reactivity studies indicate challenges that must be addressed to exploit these promising results in catalysis.We thank NSERC of Canada for funding (Discovery Grant to LR, PGS−D to RB). DAP gratefully acknowledges support by the Max Planck Society.FacultyReviewe
Shaping Experiences: Exploring the Impact of Legislation, Policy, and Programs on Family Members of MAID Recipients
No full textPublished literature on family members’ experiences with assisted dying is minimal, with only a limited number of studies exploring the perspectives of bereaved family members. Studies have shown family members can play a significant role in assisted dying. My study aimed to understand the experiences of bereaved family members who have had a loved one receive medical assistance in dying (MAID) and describe how MAID implementation, policy, and processes in two different settings in Canada influenced these experiences. The study used interpretive description, a qualitative research methodology framed by the theoretical lens of relational ethics. A total of 31 family members and 15 key informant participants took part in the study. The analysis of the data identified three descriptive themes: (a) they want MAID, now what, (b) prepared but maybe not ready, and (c) evolving understanding of this type of death, with associated subthemes that revealed the complex and layered experience of family members whose loved one received MAID. Study findings also revealed the experience of family members was influenced not only by individual-level factors but also by meso-level factors, including programs, processes, policy, and macro-level elements, including MAID legislation. These elements did not operate in isolation; instead, they interconnected to influence family members. Based on study findings, recommendations focus on policy, practice, and education, as well as future research and propose options to address the elements that affect the experiences of bereaved family members of MAID recipients.Graduate2024-12-0