title: Depositional history and downstream trends of hybrid event beds in the lower Cloridorme Formation, Quebec; implications for flow transformation in deep-water systems.

contributor: Geological Sciences and Geological Engineering

subject:
HEBs
hybrid event beds
gravity flows
turbidites
deepwater systems
sedimentology
confined system
Cloridorme Formation
Clastic sedimentology
bipartites

abstract: Submarine gravity flows build some of the largest accumulations of sediment on Earth and they host a significant portion of the world’s oil and gas reservoirs. Hybrid event beds (HEBs) are a type of deep- water sediment gravity deposit that consist of an argillaceous mud-clast rich division (debrite) that overlays a banded or structureless sandstone (turbidite). HEBs are becoming more commonly recognized as a key element of deep-water systems across a wide range of tectonic settings. However, the distribution of HEBs, where they are found within the stratigraphic framework, and their downflow trends are still being investigated. Furthermore, the role of mud in the transformation of these flows from high density turbulent flows to laminar debritic flows is not well understood. The focus of this study investigates downflow facies transitions within HEBs of the Lower Cloridorme Formation of the Gaspe Peninsula, Quebec, with a focus on facies descriptions and the systematic changes in the mud content and mud clasts in various divisions of the HEBs. The well-exposed beds along the coast of the Gaspé Peninsula allow for detailed facies classifications and tracing of individual beds. Results highlight the diversity, complexity, and abrupt downstream changes of HEB facies, which contributes to our understanding of the dynamics of hybrid flows in deep water depositional systems. Furthermore, mud clasts have been suggested to play a key role in the generation of hybrid flows. This study presents a preliminary investigation into the correlation between mud clast dimensions and the mud content within the matrix, and how their incorporation relates to the flow transformation process. Preliminary results from grain size analysis and Fourier power spectra (FPS)-based elliptic Fourier analysis of mud clasts highlight downflow changes in the sizes and shapes of mud clasts. Overall, this study investigates where HEBs are found within the stratigraphic framework and their depositional processes. Hybrid event beds in the Cloridorme Fm. are interpreted to form from either avulsion or by longitudinal fractionation as the flow moves across the muddy seafloor.

abstract: M.Sc.


title: The Development, Implementation, and Evaluation of a Social Media-Based Patient Diabetic Foot Self-Management Education and Support Program in Canada: A Multi-Method Feasibility Study

contributor:
Woo, Kevin
Nursing

rights: Queen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canada

rights: ProQuest PhD and Master's Theses International Dissemination Agreement

rights: Intellectual Property Guidelines at Queen's University

rights: This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.

rights: Attribution-NonCommercial-NoDerivs 3.0 United States

subject:
Diabetic foot ulcers
Feasibility study
Prevention
Self-management education
Self-management support
Social media

abstract:
Background: Diabetic foot ulcer (DFU) is a costly complication associated with high disability and mortality rates. Most diabetic foot care education programs are didactic and limited in providing people with diabetes (PWD) with the ongoing empowerment vital in reducing DFU incidence. The advancement in social media offers an innovative approach to empowering patients to prevent DFU.
Aim: This study aimed to determine the feasibility of social media as an alternative method to engage PWD in DFU prevention in Canada.
Methods: A multimethod approach was utilized to develop, implement, and evaluate a social media DFU prevention-based intervention. The study intervention development and implementation phase involved a participatory design that included health care professionals and PWD. The evaluative phase entailed a randomized control trial and qualitative content analysis. Data collection involved a structured questionnaire administered through QualtricsXM survey software at baseline, one, and three-month post-intervention with a telephone interview.
Results: A peer-led diabetic foot-based self-management education and support program named Diabetic Foot Care Group (DFCG) on Facebook was developed for the daily empowerment of PWD. The intervention covered ten education topics with eight categories of support/engagement activities. Thirty-two PWD were enrolled. The DFCG acceptability and efficacy rates were 84.2% and 88.9%, respectively. The participants had a positive learning experience and social interactions in DFCG. Five themes emerged to describe how DFCG helped participants change their foot self-care practice - in-depth knowledge, perceived susceptibility, sense-making, informed decision, and self-motivation.
Conclusion: Based on the findings from this study, social media is a feasible platform for the engagement of PWD in DFU prevention. PWD Engagement in the DFCG was associated with improved foot self-care efficacy, foot self-care adherence, community resources awareness, communication with health care professionals, foot health, and physical health status. Thus, health care professionals could utilize social media as a virtual option for patient education and support programs.

abstract: PhD


title: Multi-Vehicle Cooperation over Rough Terrain: Experiments with Passive Coupling

contributor:
Marshall, Joshua
Surgenor, Brian
Mechanical and Materials Engineering

subject:
Multi-robot Collaboration
robot teaming
Multi-robot control

abstract:
This work presents a passive coupling and control architecture for multiple ground robots to distribute loads across multiple robots. Six types of couplings were tested for mobilizing loads over adversarial terrain and for their ability to transfer forces in tension and compression. Couplings investigated include: Pin Joints (PIJs), Spring Joints (SPJs), Universal Joints (UNJs), Double Universal Joint s (DUNJs), Ball Joints (BAJs) and String Joints (STJs).

Experimentation showed that many joints fail under compression, leading to the robots jackknifing. The STJ performed the best in compression due to the push bar providing large flat surfaces which realigned discrepancies in robot trajectories. How ever, the STJ’s discontinuous force transfer delays switching between states of tension and compression. Of the couplings tested, the STJ offered the greatest mobility, al lowing for omnidirectional rotation and translation.

To coordinate the robots, four controllers were evaluated, including Proportional Derivative Controller (PDC), the STJ with a Virtual Damper Controller (VDC), and the SPJ with a Forward Looking Compensator (FLC) and Adaptive Position Controller (APC). In simulation, the VDC reduced the STJ impulse forces, but was difficult to evaluate on the physical robots. The FLC offered the best trajectory tracking by mapping the terrain with the first robot. The APC had stability issues with long chains. The best coupling was found to be the STJ due to its mobility, but it requires a VDC to limit discontinuous force transfers. A simple PDC was robust in all scenarios and allowed for rapid load sharing without the need for complex control or communication.

abstract: M.A.Sc.


title: A geochemical study of Paleozoic alkaline magmatism in the Selwyn Basin and the potential relationship to Zn-Pb mineralization

subject:
igneous petrology
geochemistry
geology
isotope geochemistry
sediment-hosted mineralization
economic geology

abstract:
The Selwyn Basin in the Yukon, Canada, has several occurrences of Paleozoic alkaline volcanic rocks that are spatially and temporally associated with Zn-Pb deposits. The volcanics are represented by ocean island basalt (MacMillan Pass, Misty Creek Embayment), enriched mid ocean ridge basalt (Keno Hill) and transitional basalts (Anvil District). The OIB signature indicates the MacMillan Pass and Misty Creek Embayment magmas were derived from small partial melts of an enriched lithospheric mantle during small, shallow, degrees of melting. An increased amount of extension resulted in upwelling of the asthenosphere that was sampled during melting of the transitional basalts in the Anvil District.
	Strontium isotopes of the Selwyn Basin volcanic rocks show evidence for interaction with Paleozoic seawater and several samples display highly radiogenic 87Sr/86Sr values due to crustal contamination. The volcanic rocks have low 143Nd/144Nd values and are representative of the source region. Mixing occurred between a highly radiogenic and less radiogenic Pb source. The Keno Hill samples plot near MORB values. The isotopes for both MacMillan Pass and Anvil volcanics plot between EMII-like and HIMU-like mantle end members, suggesting melting of a heterogenous lithospheric mantle with two end members; an enriched reservoir (low Nd, average Pb, high Sr) and a highly radiogenic Pb reservoir (high Pb, average Nd, low Sr). A depleted mantle source may be contributing to the Keno Hill samples.
	Thallium isotopes of the volcanic rocks have negative values that decrease with increasing degree of alteration. The MacMillan Pass samples have the smallest ɛ205Tl compositions while the Anvil samples overlap with OIB and MORB values and the measured ɛ205Tl range of mineralized rocks from Anniv East at Howard’s Pass. Ratios of certain trace elements (Tl, Ba, In, Ag) of host rocks for mineralization at Howard’s Pass and MacMillan Pass trend towards the values of Selwyn volcanic rocks. Mineralized samples plot at the overlap between their host rocks and the volcanic samples. This may be due to alteration of volcanic rocks by mineralizing fluids. Volcanic rocks may have been leached alongside basinal sediments during deposit formation but there is no evidence for a direct contribution to mineralization.

abstract: PhD


title: Deep Representation Learning for Speaker Recognition

contributor:
Etemad, Ali
Electrical and Computer Engineering

subject:
Speaker Recognition
Speaker Representation Learning
Deep Learning
Deep Neural Networks

abstract: Automated SR solutions are often used in smart devices that are capable of recording audio for authentication purposes or to personalize the services provided by these devices towards each user. Over that past few years, deep learning solutions for SR have attracted large amounts of attention. The superior performance of deep learning models in challenging conditions compared to the classical methods, specially in noisy environments and in-the-wild scenarios, have made them a predominant choice for developing SR models. However, there are some challenges that remain less explored in the literature. We select several interesting challenges as the objective of this thesis, namely, using short utterances for SR, focusing on salient parts of input speech, enhancing the back-end component of SR solutions, using video during the training of SR models, and analyzing fairness in common SR solutions. As our first challenge, we proposed a new deep neural network, UtterIdNet which is capable of achieving strong SR results with short speech segments especially sub-second durations (250 ms and 500 ms). For the second goal of this thesis, we proposed FEFA which is capable of focusing on information items as small as frequency-bins while being simple and lightweight. We showed through experiments that by adding FEFA to different CNN architectures, performance is consistently improved by substantial margins. For the third challenge, we proposed a Siamese capsule network to replace the back-end of SR systems. Our experiments showed that using this model the performance of SR systems are considerably enhanced. For addressing the fourth challenge, we adopted the paradigm of learning using privileged information and teacher-student knowledge distillation to train student models that perform SR on audio input only while their training is boosted by the teacher models that learn video inputs. Our evaluations showed that using this method improves the performance of student models considerably. Finally for the fifth challenge, we analyzed the impact of using different networks and loss functions on the fairness of SR systems towards `gender' and `nationality' as protected groups. Our analysis provides new and interesting insights into the fairness of recent common SR systems.

abstract: PhD


title: Rethinking Digital Divides: a qualitative examination of technology, place, and capital in rural Ontario

contributor:
Hand, Martin
Sociology

subject:
Rural Technology Adoption
Rural Digital Divide

abstract: This thesis investigates how urban-rural digital divides are imagined by Canadian broadband policies, and how these narratives compare to the lived experience of rural residents of Kapuskasing, Ontario. In doing so, this project critiques two underlying assumptions in federal policies: 1) that digital communication technologies ‘develop’ rural communities by superseding rural practices, and 2) that technology inherently fosters the skills necessary to overcome existing social inequalities. Of interest in this research are the patterns of technology domestication, and how ‘rurality’ might influence the practices of residents in these locales. The analysis reveals some of the ways in which rural residents have agency in processes of technology domestication and suggests that existing inequalities are as likely to shape the adoption, use, and outcomes of new digital technologies as they are to be overcome by them.

abstract: M.A.


title: Computing β For Certain Schubert Subvarieties

contributor:
Roth, Mike
Mathematics and Statistics

subject:
Algebraic Geometry
Representation Theory

abstract:
This thesis focuses on the invariant βY (L) attached to a triple (X, Y, L), where X
is an irreducible projective variety, Y ⊂ X is a proper subscheme and L is a big or
ample line bundle on X. This invariant has emerged independently in various papers,
where it was used to attain new results in Diophantine geometry and mathematical
physics. We pursue the task of computing βY (L) in the case where X = G(k, n),
Y ⊂ X is a Schubert subvariety and L = OX (1). We develop a method by which
we can compute βY (L) for any Schubert subvariety Y , provided that we satisfy some
hypotheses; these hypotheses can be difficult to check, and the resulting formula can
be difficult to evaluate. As our final result, we prove a concise formula for βY (L) when
Y is a special type of Schubert subvariety, which we refer to as a maximal rectangle
Schubert subvariety (abbreviated by MR Schubert subvariety).

abstract: M.Sc.


title: Design and Implementation of a Secure Communication Architecture

contributor:
Zulkernine, Mohammad
Computing

subject:
Security Protocol
Public Key Infrastructure
Group Key Exchange
Perfect Forward Secrecy
Authentication
PKI
GKE

abstract: Internet communications transitioned from the traditional client-server model to the cloud model and are going towards a decentralized hybrid model. The communications are protected by the traditional security protocols. The participants (especially, server-side) are authenticated using a certificate authority (CA)-based public key infrastructure (PKI). However, the security protocols and the CA-based PKI are not always able to address the challenges associated with these communications. The significant growth in online activities in our everyday life over time increases the associated security threats even more. The lack of an efficient and scalable group key exchange (GKE) for secure group communications escalates the severity of the associated security threats even further. In this thesis, we design and implement a comprehensive secure communication architecture for any Transmission Control Protocol (TCP) and User Datagram Protocol (UDP)-based internet communications between two or more participants. This architecture can address the associated security threats and overcome the shortcomings of the traditional security protocols and the CA-based PKI. This work involves the designing of a security protocol that works for both TCP and UDP communications, a distributed key server-based PKI for authentication, and a secure authenticated scalable group key exchange. This architecture ensures security for the data-in-transit in any TCP and UDP-based secure communications. The proposed PKI solves the certificate mis-issuance and revocation problems of the CA-based PKI. The proposed GKE ensures the security for static and dynamic group communications between large number of participants. It supports change-of-membership (i.e., adding or removing participants in an existing group communication) efficiently. The architecture protects the communications against some most common attacks, such as man-in-the-middle (MITM) (including eavesdropping, sniffing, identity spoofing, data tampering), sensitive information disclosure, compromised-key, key tampering, certificate mis-issuance, certificate cloning, repudiation, replay, and re-negotiation attacks. The results show prominent evidence that the designed architecture effectively enhances the security of TCP and UDP-based internet communications between two or more participants, offers adequate performance over the traditional security protocols, and overcomes the limitations of the traditional security protocols and the CA-based PKI.

abstract: PhD


title: Characterization of tailings, sediments, and vegetation and their impact on metal(loid) mobility in the Cobalt Mining Camp, Ontario

subject:
environmental geochemistry
Cobalt, Ontario
metal mobility
arsenic
cobalt

abstract:
This study investigates the mineralogical, geochemical, and vegetation-related controls on metal(loid) mobility from historical mine wastes in the Cobalt Mining Camp in Ontario. The research focuses on arsenic (As) and cobalt (Co) mobility as these elements are potentially harmful to the environment and because Co is an economically important critical metal in Canada. Comprehensive mine waste characterization is necessary prior to excavating tailings for remediation or reprocessing purposes.
Mineralogical and geochemical analyses were performed on tailings from four deposits and pond sediments in Cobalt. The mass of readily soluble metal(loid)s in the tailings and sediments was evaluated using a shake flask experiment. Horsetails (Equisetum sp.) growing on the tailings were collected for chemical characterization and backscattered electron imaging.
The tailings and sediments collected in 2021 contain As and Co concentrations (1,200 to 20,000 ppm As; 534 to 8,900 ppm Co) that exceed Canadian environmental quality guidelines for sediment (5.9 ppm As) and soil (50 ppm Co). The benthic sediments contain higher concentrations of most metal(loid)s relative to the nearby tailings. Arsenic and Co are hosted in primary minerals, alteration phases, and phases formed during mineral processing. The proportion of oxidized and reduced phases varies between the different depositional environments. Metal(loid)s that dissolved during the shake flask experiment include As (1,370 to 325,000 µg/L As) and Co (30 to 126,000 µg/L Co), both of which exceeded Canadian water quality guidelines for the protection of aquatic life (5 µg/L As; 1 µg/L Co). During the experiment, sulfide dissolution generated acid which facilitated leaching of metal(loid)s from solid phases. The horsetails contain elevated metal(loid) concentrations in the roots of the plant relative to the aboveground mass. Arsenic is sequestered by an oxidized Fe-bearing plaque on the horsetail roots.
This study demonstrates that metal(loid) mobility in Cobalt is controlled by geochemical conditions in the mine waste, solid phase hosts, and vegetation growing on the tailings. Changes to redox conditions could mobilize metal(loid)s from tailings and sediments in Cobalt. These results can be used to inform long-term management decisions regarding the unremediated mine waste in the Cobalt Mining Camp.

abstract: M.Sc.


title: Distributed Control Algorithms for Solving Large-scale Optimization Problems of Networked Systems

contributor:
Guay, Martin
Chemical Engineering

subject: Distributed control

subject: Control algorithms

subject: Large-scale systems

subject: Large-scale optimization

subject: Convex optimization

subject: Networked systems

subject: Extremum seeking control

subject: Newton consensus

subject: Communication networks

subject: Cooperative distributed control

subject: Wind farms

subject: HVAC systems

subject: Uncooperative distributed control

subject: Resource allocation

subject: Distributed algorithms

subject: Distributed optimization

subject: Distributed control algorithms for solving large-scale optimization problems of networked systems

abstract:
Large-scale networked multi-agent systems are becoming complex and highly integrated. To control and optimize such a system would require the use of algorithms that are flexible, scalable, effective, efficient and robust. This dissertation considers the development and application of distributed techniques capable of handling control/optimization problems of these systems. Specifically, problems in the areas of power and energy, and resource allocation are investigated. They are solved as consensus-based optimization problems in situations where communication and collaboration are possible.

For systems that cannot be accurately described by a model, the development of  model-free distributed control techniques is proposed for system optimization. In this thesis, the design and implementation of model-free distributed algorithms using extremum seeking control is presented for the solution of three different optimization problems. First, the power maximization of an offshore wind farm under fixed and varying free stream wind speeds and directions. Second, the power minimization of a heating, ventilation and air condition system, precisely, a two rooftop air conditioning system with continuously varying capacities (the compressors modulate rather than turn off and on). Finally, the minimization of a resource allocation problem for a class of multi-agent dynamic system subject to some resource constraint.

When a model exist for the large-scale system considered, model-based distributed algorithms are favourable. This thesis proposes the development and implementation of a model-based method, a Newton consensus distributed technique for the solution of a multi-agent multi-resource allocation problem. This technique, a second-order method overcomes some of the challenges associated with using first-order methods such as extremum seeking control in the following ways. First, it takes away the need to impose feasible initial conditions. Second, it speeds up convergence and thirdly, reduces the effect of the communication network structure on the performance of the system.

abstract: PhD


title: Polymer Culvert Liner Response to External Water Pressure Considering Buoyancy and Non-Circular Geometry

contributor:
Tara, Mohammdamin
Civil Engineering

subject:
Culvert
Liner
Buoyancy
Water Pressure

abstract:
Although CIPP is one the most reliable methods for trenchless rehabilitation of old pipes, little research has been conducted in regard to the rehabilitation of culverts using CIPP considering the impacts of shallow cover, where the water pressure increases with depth lead to significant buoyancy. Buckling is one of the important strength limits for liners under groundwater pressure and solutions exist for expected buckling pressure. Solutions also exist for bending moment and hoop force induced by the external groundwater pressure, permitting assessment of the potential for yield. However, all these available solutions were formulated considering deeply buried structures, where pressure variations between the crown and invert are neglected. Furthermore, they were developed for nearly circular sewer geometry, and do not encompass the ellipse shapes used in some corrugated steel culverts.
The goal of this study is to develop an analysis that incorporates buoyancy and to examine the impact of buoyancy on buckling pressure, moment, and thrust, for circular and elliptical culvert structures.
Using 38 example cases involving liners loosely fitting within a host pipe, and 36 example cases involving liners in elliptical host pipes, it was demonstrated that one of the liner buckling solutions of Thépot provides effective estimates of critical external water pressure at the invert. The same example cases were used to assess the performance of Thépot’s solutions for moment and thrust in the liner. New correction factors are proposed to modify those solutions for elliptical host pipe geometry so they provide moment and thrust estimates that are close to finite element calculations.

abstract: M.A.Sc.


title: Multi-Joint Topology Optimization for Stiffness Constrained Design Problems

contributor:
Kim, Il Yong
Mechanical and Materials Engineering

subject:
Topology optimization
Multi-material joining
Lightweight design
Mass minimization
Stiffness constraints

abstract:
Computational tools such as topology optimization (TO) have long been utilized in industry to reduce mass while meeting structural design constraints. Over time, TO methods have been extended from traditional single material topology optimization (SMTO) to advanced methods such as multi-material topology optimization (MMTO). These advanced computational tools provide more design freedom in the conceptual design phase to develop superior load paths not possible with SMTO. However, MMTO is limited by the assumption of perfect joining between dissimilar materials, requiring manual re-interpretation to develop manufacturable designs. Multi-joint topology optimization (MJTO) has been developed to incorporate material joining within the optimization loop, producing designs which require less manual interpretation and demonstrate more physically meaningful structural performance.
To promote the application of MJTO to more practical design problems, this work presents an extended MJTO methodology which addresses the limitations of previous approaches. Initial work focuses on improving interface quality and convergence stability of compliance-based problems through the implementation of a revised interface detection method and a new combined filtering scheme. A new joint material modelling approach is introduced which addresses the discrepancy between physical joint thickness and finite element size by leveraging numerical homogenization techniques. Finally, the MJTO problem is extended to include capability for mass minimization subject to stiffness constraints, offering a new problem type which is far more applicable to practical design problems. Academic and practical level case studies are included throughout, including comparisons to previous approaches, to demonstrate the effectiveness of the new MJTO algorithm for practical design problems.

abstract: M.A.Sc.


title: Investigating Pathogenic Mechanisms and Biomarkers in Alzheimer’s Disease

subject: Alzheimer's

abstract:
Alzheimer’s disease (AD) is the most common form of dementia among the elderly and a major public health issue worldwide. Despite decades of research efforts, AD still lacks an effective treatment. Although the first two histopathological markers of AD identified in the 1980’s are brain deposits of extracellular amyloid β (Aβ) and intraneuronal tau, more recently, other pathways have been implicated in disease pathophysiology. Modifiable risk factors associated with lifestyle interventions, including diabetes, depression and sedentarism, are linked to AD, and the identification of shared molecular mechanisms between these risk factors and dementia has the potential to contribute to elucidate disease etiology. A big obstacle in developing therapeutics for AD is the difficulty in diagnosing this disease before substantial neuronal loss and cognitive impairment. In this context, blood has emerged as a promising cost-effective and less invasive source of disease biomarkers in patients.
This thesis aims to investigate pathogenic mechanisms associated with AD, including inflammation, metabolic dysfunction, and impaired hormonal signalling, and to propose a novel approach to measure in vivo biomarkers in blood samples from neurodegenerative disease patients. More specifically, findings presented in this thesis indicate a role for pro-inflammatory interleukin-6 (IL-6) and tau pathology in mediating metabolic and cognitive alterations in AD mice; propose a novel shared molecular signature between depression and dementia involving reduced cerebrospinal fluid (CSF) levels of the exercise-induced hormone irisin and the pro-resolving and anti-inflammatory mediator lipoxin A4; describe an approach to identify biomarkers of neurodegeneration from patients’ blood samples using neuronal-derived extracellular vesicles (NDEVs) purified using the synaptic marker synaptosomal-associated protein 25 (SNAP25). Overall, these results are relevant to our understanding of AD pathogenic mechanisms and disease biomarkers.

abstract: PhD


title: “To Be a Poet and a Poem”: The Life of Literature and the Metafictional Self in A. S. Byatt’s Possession

contributor:
Willmott, Glenn
English Language and Literature

subject:
A. S. Byatt
Possession
Metafiction
Self
Identity
Wonder
Melusine
Melusina
Christabel LaMotte
Life Metaphors
Writer
Reader
Writing
Reading
Literary Self
Literature
Life of Literature
Imagination
Creativity
Artistic Subjectivity
Feminine Subjectivity
Woman Artist
Poet
Literary Scholarship
Byatt
Possession: A Romance
Interpretation

abstract: This thesis examines the relationship between the self and literature in A. S. Byatt’s Possession: A Romance, analyzing the novel’s portrayal of writing and reading as processes of self-construal. The central concept explored is the idea of a literary self: a dimension of a writer’s self which exists in and through literature, in the simultaneous expression and creation of the self with words. Through an exploration of Possession’s metaphors about the life of literature, the paper both defines the literary self and demonstrates that Byatt’s characters have a life in poetry which transcends their individual mortality and which is related to, but not bound by, the events that constitute, and often constrain, their personal histories. The thesis also considers the dynamics of reading, examining both how reading is depicted within the narrative and how we read Possession, a novel which presents various discussions about poetic composition and literary scholarship alongside the works, supposedly written by the characters, which Byatt’s fictional and real readers alike attempt to interpret. The paper argues that, as a metafictional text, Possession blurs the boundary between fiction and criticism, and that the novel both portrays and prompts the reading of the literary self, such that what it narrates is simultaneously the representation of a fictional act and a real experience. This analysis of Possession’s interplay of life and literature focuses on the characterization of the fictional Victorian poet Christabel LaMotte in relation to her poem The Fairy Melusine. The paper argues that, rather than reading LaMotte and Melusina as merely symbolically connected, recognizing LaMotte’s position as the author of Melusine is crucial to discovering the poet through her poem since, although LaMotte and Melusina share many characteristics and experiences, one crucial difference ultimately separates them: while Melusina is defined by her story, LaMotte has the agency to define herself by writing Melusine. The paper also considers the feminist valences of LaMotte’s Melusine, examining the visions of feminine artistic subjectivity and creativity which Melusina embodies. The thesis concludes with an exploration of the need for wonder in the writing and reading of the literary self.

abstract: M.A.


title: Machine Learning Model Stores: A Construct of Software Engineering for Artificial Intelligence

contributor:
Stinson, Catherine
Computing

subject:
Machine Learning
Software Engineering

abstract:
Machine learning as a discipline continues to evolve, today developers, business and other entities are seeking to build applications from machine learning models and datasets, giving rise to a new discipline of SE4AI. As a parallel development, the development of machine learning model stores has become a prominent trend.

Machine learning model stores like Hugging Face integrate a series of processes that allow for the reuse of datasets and models. First, Hugging Face provides standards based on academic research in order to facilitate the documentation of models and datasets. Second, they provide tools to train and deploy datasets and models more easily. Third, they provide infrastructure such as git, to maintain these artifacts. These elements are provided with the objective of facilitating the development and usage of machine learning artifacts so that they may be more easily integrated into production environments.

However, while these developments show promise, there is little research on how they operate. In terms of documentation, there are standards which have been used by Hugging Face, but they have not been empirically validated yet. In the same way, there is research that talks about the common problems present in the machine learning development lifecycle, but empirical validation of such issues. Additionally, while issues relating to the evolution of software development problems have been researched before, these have largely remained unexplored within machine learning. In this research we address two problems related to the latter. First, we analyze the documentation practices present throughout the models and datasets in Hugging Face, to determine how closely these resemble the practices established by previous standards. We also look into how dependencies between datasets exist in Hugging Face and how these are documented by the model store. Second, we performed a thorough statistical analysis of the commit history data pertaining to model, dataset, and spaces in order to determine the effort necessary to maintain and run a model store. Our findings by provide useful information to developers on what they can expect to find in terms of documentation in models stores and how much effort is needed to  maintain these artifacts.

abstract: M.Sc.


title: Green Federated Learning over Wireless Networks

contributor:
Lu, Ning
Electrical and Computer Engineering

rights: Attribution-NonCommercial 3.0 United States

subject:
Federated Learning
Distributed Machine Learning
Communication-efficient FL

abstract:
Motivated by ever-increasing computational resources at edge devices and increasing privacy concerns, a new machine learning framework called Federated Learning (FL) has been proposed. FL enables user devices, such as mobile and Internet of Things (IoT) devices, to collaboratively train a machine learning model by only sending the model parameters instead of raw data. FL is considered the key enabling approach for privacy-preserving, distributed machine learning (ML) systems. However, FL requires frequent exchange of learned model updates between multiple user devices and the cloud/edge server, which introduces a significant communication overhead. Moreover, FL consumes a considerable amount of energy in the process of transmitting learned model updates. In this thesis, we aim to engineer a green FL framework over wireless networks that is both communication-efficient and energy-efficient. To improve communication efficiency, we will design two novel model compression approaches, and to improve energy efficiency, we will develop a joint network scheduling and model updating. Our solutions will be validated extensively through real-world experiments.

More specifically, in our first communication-efficient method, we propose the Federated Learning with Autoencoder Compression (FLAC) approach that utilizes the redundant information and error-correcting capability of FL to compress user devices' models for uplink transmission. FLAC trains an autoencoder to encode and decode users' models at the server in the Training State, and then, sends the autoencoder to user devices for compressing local models for future iterations during the Compression State.

In our second communication-efficient method, we introduce the Dynamic Sparsification for Federated Learning (DSFL) approach that enables users to compress their local models based on their communication capacity at each iteration by using two novel sparsification methods: layer-wise similarity sparsification (LSS) and extended top-K sparsification.

In our energy-efficient FL design, we investigate the energy consumption of transmitting scheduling decisions for FL deployed over a wireless network. To this end, we propose a novel multi-frame framework that enables the coordinator to schedule wireless devices at the beginning of each global round and set the coordinator's transmission module to sleep mode.

abstract: M.A.Sc.


title: Ideology and Praxis: A Critical Analysis of the Marx-Hegel Relationship in Connection with Antagonistic Conceptions of Ideology in Marxism

contributor:
Beamish, Rob
Sociology

subject:
Marxism
Objective Idealism
Sociology
Hegelian Philosophy
German Idealism
Georg Lukács
Karl Marx
Friedrich Hegel
Friedrich Engels
Vladimir Lenin
Karl Kautsky
Orthodox Marxism
Hegelian Marxism
Ideology
Praxis
Consciousness
Phenomenology
Joseph Stalin
Marxism-Leninism
Dialectical Materialism
Marx-Hegel relationship
Dialectics

abstract: This study analyzes differing conceptions of ideology (i.e. the subject of ideas) attached to Marx’s materialist conception of history, across various Marxist streams in relation to the theorization of political praxis. The analysis centers on the antagonistic relationship between humanist and deterministic conceptions of ideology and explores how particular interpretations of the role of ideas in history came to dominate Marxism. Through critical analysis of Marx’s internal development, a direct connection is made between understandings of Marx’s latent Hegelian influences and various conceptions of ideology which can be explained by the degree to which later Marxists embraced or rejected key elements of Hegel’s philosophy of Objective Idealism: i.e., his dialectical form and/or phenomenological content. After having elaborated on the nature of the Marx-Hegel relationship through this lens, four critical interpretations of ideology (and its relation to praxis) are examined and compared/contrasted with Marx’s dual-inversion of Hegel’s form and content: (1) the Orthodox Marxism of the Second International and its theoretical errors which descend from Engels’s framing of the Marx-Hegel relationship, (2) Lenin’s decisive rediscovery of Hegel, (3) Stalin’s Diamat, imposed on the Third International, and (4) Lukács’s philosophical elaboration of Lenin’s thought. The analysis shows that Lenin’s and Lukács’s interpretation of the Marx-Hegel relationship accurately defines dialectical form from the standpoint of totality and therefore embraces the phenomenological content of Hegel’s Objective Idealism through a more nuanced conception of ideology as both a product of the material world and hu-man subjectivity. Antagonistically, Engels, the Orthodox Marxists, and later Marxist-Leninists, placed a singular emphasis on Hegel’s form which produced an inflexible, deterministic account of social development in which ideas (and therefore consciousness) are the one-sided expression of the objective laws of matter. The former models how contemporary sociology ought to narrow the gap between social theory and human material existence by taking a praxis-oriented approach to social issues that acknowledges the unique creative faculties of consciousness which allow humans to play an active role in their own social development.

abstract: M.A.


title: Deformation Rate-dependent Behavior of AlSi10Mg Alloy 3D-Printed via Laser Powder Bed Fusion

contributor:
Fallah, Vahid
Mechanical and Materials Engineering

subject:
Additive Manufacturing
Deformation Behavior
Al Alloys
Microstructure

abstract: Strain rate sensitivity, deformation rate-controlling mechanisms, and work hardening behavior of AlSi10Mg alloy, 3D-printed via laser powder bed fusion, were comprehensively assessed as a function of strain, strain rate and stress state, considering the as-built optimized microstructure. Accordingly, in the first step, the process parameters were optimized for as-built samples printed with a new specialty spherical powder before further assessment of mechanical performance of 3D-printed samples; i.e., different powder attributes were compared with the common machine’s default powder with non-spherical particle morphology. A novel 4-step process parameter optimization method was developed for the first time. The proposed approach involves the effective use of prevalent energy density/enthalpy models complemented by an in-depth microstructural and mechanical characterization. Using a formulation derived from functioning characteristics of a pulsed-wave laser system, a reliable volumetric energy density (VED) model is developed, from which a trend in VED-porosity relationship is identified. This 4-step optimization method resulted in the selection of “SO1”, sample with superior mechanical properties (ultimate tensile strength of ~461 MPa and elongation to fracture of ~9.8%). This optimized as-built sample was used for all further microstructural and mechanical analysis. A strong non-linear strain rate sensitivity behavior was observed after room temperature tensile and compressive deformation at different constant strain rates (quasi-static range, 10-4-10-1 s-1, and medium-dynamic regime, 1-5 s-1). For both stress states, except for a negative strain rate sensitivity in 10-2-10-1 s-1 range, a positive trend was observed.  This negative strain rate sensitivity was correlated with the deformation-induced microstructural evolution, i.e., manifested as a gradual transition in the dominant dislocation-precipitate interaction mechanism from shearing to looping, along with the disappearance of dislocation-solute interaction in the form of dynamic strain aging. The precise measurement of activation volume evolution with flow stress further confirmed the transition from shearing to looping in the 10-2-10-1 s-1 range. Shear band formation was observed for the first time after compressive deformation above ~0.05-0.07 strains, with higher intensity at higher strain rates (e.g., 5 s-1). Using the Kocks-Mecking model, the unique work hardening behavior of as-built samples were correlated to the evolution of extra-fine, non-equilibrium as-built microstructure during deformation.

abstract: PhD


title: “Canada in One City”:  Austerity Urbanism and the Financialization of Ottawa's Private Rental Sector

contributor:
Soederberg, Susanne
Political Studies

subject:
financialization
austerity urbanism
private rental sector
Ottawa
Vanier
Herongate
gentrification
neoliberalism
Ontario
Canada
housing
affordability

abstract: This project centres on the financialization of private rental housing in Canada, and Ottawa, Ontario in particular. With some exceptions (August and Walks, 2018; August, 2020; Crosby, 2020, Nethercote, 2020; August, 2021) there has been relatively little scholarly focus on the financialization of rental housing in Canada—and even less on Ottawa—but understanding this process of housing financialization in the PRS is important because it helps scholars understand how macroeconomic restructuring relates to important issues in private rental housing like weakened rent protections, evictions, and urban planning. Researching the financialization of the PRS also furthers academic debates on neoliberal inter-scalar governance (Brenner, 2019) and the role of resistance and revanchism in shaping urban geographies (Harvey, 2012; Purcell, 2013; Lawton, 2018; Albet and Benach, ed., 2018). Accordingly, my dissertation asks four key questions: First, what role has the neoliberal and inter-scalar Canadian state played in shaping financialization in private rental housing? Second, how have resistance and revanchism at different scales impacted the financialization of rental housing in urban areas? Third, how have forms of resistance and revanchism under neoliberalism yielded variegated geographies? And, finally, how can resistance and revanchism be understood in relation to shaping the financialization of private rental housing? My research reveals that the Canadian state—across federal, provincial, and municipal scales—has played a critical, structural role in implementing neoliberalization and financialization in the PRS. With organized labour and housing movements in a historically deficient phase, capitalist interests and revanchist movements have been able to reorder governance scales to favour the private rental market and enable processes like gentrification. In order to argue this two-pronged thesis, I deploy historical-geographical materialist (HGM) theory (Harvey, 1989; Smith, 1996; Swyngedouw, 2000), which reveals the class-based nature of financialization in the PRS and particular ways in which rent extraction and urban revitalization are shaped by historical and geographical specificities. I advance this argument through two case studies, which reveals how two gentrifying and historically lower-income communities in Ottawa—Vanier and Herongate—are undergoing unique forms of revitalization according to their particular historical development across the inter-scalar austerity urbanist planning regime.

abstract: PhD


title: Multidisciplinary Design Optimization of Nose Landing Gears with Two Degrees of Freedom Considering Out of Plane Loading and Actuator Performance

subject: Multidisciplinary Design Optimization (MDO)

subject: Landing Gear

subject: Kinematics

subject: Dynamics

subject: Structural Optimization

abstract: Multidisciplinary design optimization (MDO) is a mathematical optimization technique for designing engineering systems that involve multiple disciplines. By implementing the MDO technique, engineers can design complex systems by simultaneously considering multiple branches of physics without manual iterations. The design of lightweight retractable aircraft landing gear is a sophisticated multidisciplinary problem. It is difficult to finalize the design through manual iterations, especially under the demands of an accelerated product development process. MDO methodology has been previously developed to design a planar four-bar mechanism for retractable nose landing gears with one degree of freedom (DOF) to minimize mass with simultaneous structural and kinematic optimization. Although the methodology has demonstrated the viability of MDO for designing a retractable nose landing gear under the demands of a shortened product development process, there is no existing MDO methodology that can be implemented to design lightweight retractable nose landing gears with two DOF considering hydraulic cylinder performance and out-of-plane load cases. This thesis presents an MDO methodology for simultaneous structural and multi-body dynamic optimization of retractable nose landing gear main fitting, side brace, and lock link assemblies, where the goal is to minimize mass. The methodology has been implemented using Python to generate three different landing gear designs for three commercial aircrafts with out-of-plane load cases based on European aircraft certification requirements. The resultant designs demonstrate that the proposed MDO methodology can determine an ideal wheel diameter, cross-sectional dimensions, and revolute joint distances of all the landing gear members in the preliminary design phase.

abstract: M.A.Sc.


title: Crashworthiness Multi-Material Topology Optimization for Minimum Mass

subject:
optimization
crashworthiness
design
topology optimization
automotive design
multi-material design
multi-material topology optimization
computer aided engineering
CAE
FEA
Finite Element Analysis
Equivalent Static Load Method

abstract:
There is an increasing need for lightweight structures in the transportation industry, and within these lightweight structures crashworthiness and occupant safety is continually important to all stakeholders. Industry standard lightweighting tools such as topology optimization (TO) and emerging techniques like multi-material topology optimization (MMTO) are effective for designing lightweight structures subjected to linear loading, but they cannot consider dynamic crash loading. Crashworthiness is most effectively simulated using dynamic finite element analysis (FEA) techniques due to the geometric and material nonlinearities involved in a crash event. Dynamic simulations do not allow for the calculation of analytical sensitivity derivatives required for conventional gradient-based structural optimization strategies. Non-gradient based methodologies for crashworthiness optimization exist in the literature which optimize structures via direct use of dynamic responses, but they are prohibitively computationally expensive and require heuristic strategies for design evolution. The equivalent static load (ESL) method is used to generate linear static sub-problems which replicate the dynamic structural responses of crash simulations in the linear regime, such that they can be used in a relatively standard gradient-based TO problem. Resulting designs from the ESL problems are used as input for subsequent crash analyses to update the ESLs for additional sub-problems.

The objective of this thesis is to develop a novel methodology for a MMTO design tool considering crashworthiness using a gradient-based optimization strategy. The dual loop optimization strategy using the ESL method is presented, along with a discussion of the tool’s operation flow and the material modelling and interpolation schemes. The new MMTO for crashworthiness methodology is demonstrated with three case studies. Comparisons between single and multi-material TO solutions are presented to show the benefit of MMTO when developing advanced designs. When applied to a Formula SAE chassis minimum-mass design problem with crashworthiness considerations, the MMTO tool developed in this work obtains a result with 30% better performance compared to the best design found with single-material TO.

abstract: M.A.Sc.


title: Tracing The Origin Of A Lectin-like Antifreeze Protein

contributor:
Davies, Peter
Biomedical and Molecular Sciences

subject:
Biochemistry
Antifreeze Protein
Gene Duplication and Divergence

abstract:
Type II antifreeze proteins (AFPs) are C-type lectin homologs found in three lineages of teleost fish (Cottidae, Clupeiformes and Osmeriformes). Previous work demonstrated that the AFP gene was horizontally transferred from the Atlantic herring to the smelt, and also showed that the herring is not the progenitor species. Questions remain regarding the origin of the type II AFPs, and the relationship between Ca2+-dependent and Ca2+-independent subtypes.
In this thesis, I explore the hypothesis that the Ca2+-dependent type II AFP originated in the cottid lineage from a lectin and then gave rise to a Ca2+-independent AFP from a gene duplication and divergence event. Protein, expressed sequence tag, and genomic databases were searched for putative type II AFP sequences. Candidate AFP-like proteins were only found in Eupercaria but were not limited to cottids. Proteins were modelled using Modeller and ColabFold, then evaluated based on conservation of residues potentially involved in ice- and Ca2+-binding. The current habitat and distribution of these species was evaluated in terms of the need for AFPs. In several species, genes for predicted Ca2+-dependent and Ca2+-independent proteins were found back-to-back at the same syntenic locus. Numerous type II AFP-like candidate proteins were identified for future research, and patterns in residues of significance may be used to further refine search criteria for AFP discovery.
Additionally, I attempted to produce type II AFPs using a mammalian HEK293E expression system and a Drosophila expression system. Secretion of active AFP from HEK293E cells was unsuccessful, possibly due to the stressors of high temperature and protein overproduction. Expression in the Drosophila cell system was attempted at a lower temperature but did not yield secreted AFP for characterization.

abstract: M.Sc.


title: A Gaussian Process Model for the Local Galactic Velocity Field

contributor: Physics, Engineering Physics and Astronomy

subject:
Galaxy
Model
Gaussian Process
Star

abstract: The Milky Way Galaxy has been a source of inspiration and challenge for astronomers who have focused their efforts to understand the motions of stars, the spin of the Galaxy, and the connection beyond to dark matter and our universe. These efforts are being propelled by the Gaia mission, a space observatory dedicated to cataloging more than one billion stars in the Galaxy. Gaia has observed more than 33 million stars with both the positions and velocities in each dimension to give a full six dimensional solution. The next challenge in Galactic astronomy is to analyze and understand how the Galaxy’s motion fits with our knowledge of theory, and the departures within. The size and complexity of the data make it a challenge to analyse the underlying motion. In this thesis we focus on the mean velocity field in the vicinity of the Sun. A number of researchers have constructed views of Galactic motion via binning. While conceptually simple, the connection to theory can be tenuous. Here we use Gaussian process regression, a non-parametric machine learning method that presents an opportunity for modelling the bulk motion of the Galaxy. This method can inform both the current motion and future state of the Galaxy, calculating continuous derivatives of the velocity field. We discuss the use of observational data with Gaussian process regression, modifications to modelling for use with large data, and highlight the observed motions and their connection to our understanding of the Galaxy. Models agree strongly with Galactic motions explored in literature, and provide a measure of the divergence for examining time evolution of regions of the Galaxy.

abstract: M.Sc.


title: The Prosocial Behaviour of Shy Children

contributor:
Kuhlmeier, Valerie
Psychology

subject:
shyness
prosocial behaviour
helping
comforting
sharing
sociocognitive development

abstract: Shyness appears to be a major barrier to prosocial behaviour in young children, making them less likely to help, share with, comfort, or cooperate with people in need. In this dissertation, I explore the root causes of shy children’s lower rates of intervention and seek to identify the conditions in which they will be less likely, or slower, to intervene than their not-shy peers. I begin, in Chapter 1, by critically reviewing the current literature, synthesizing findings into three main implications, and identifying major issues that should be addressed in future research. In Chapter 2, I address one of these issues: that past research has primarily framed shyness as a factor that affects children’s motivation to intervene without considering its effect on their understanding of how to do so. In that chapter, I describe a study we conducted to test how preschool children would respond to prosocial tasks that varied systematically in their complexity and social engagement demands. Chapter 3 addresses two other limitations in the current literature: that past research has focused on how shy children react to prosocial situations in the lab, involving only adults, and that many studies have measured the broader construct of social withdrawal as a proxy for shyness. For that study, we examined how children would respond to an experimenter in a structured individual setting compared to their peers in a naturalistic, daycare group setting. We measured shyness by observing how often they displayed reticent behaviour during a free-play period, which is a specific type of social withdrawal that has been linked to anxiety in past research. Finally, in Chapter 4, I review the practical implications of our findings and raise important questions for future research.

abstract: PhD


title: Digital Ideation: Postsecondary Student Creative Thinking Experiences Using Online Peer Assessment

contributor:
Bolden, Ben
Education

subject:
Creativity
Creative thinking
Collaboration
Collaborative learning
Peer assessment
Online peer assessment
Brainstorming
Divergent thinking
Teamwork
Team-based learning
Project-based learning
Learning technologies
Problem-based learning
Groupwork

abstract: Groupwork and the ability to think creatively are critical skills that help drive societies forward and are top attributes employers look for in graduates. While these skills are often integrated into curriculum, postsecondary institutions must do more to advance these skills in learners. Researchers have explored how emerging technologies such as online peer assessment support higher order skill development in postsecondary students. While studies have focused on peer-to-peer assessments, there has been limited investigation into ways that online peer assessment could support creative thinking within teams. An explanatory mixed methods approach was used to explore postsecondary student creative thinking experiences using online peer assessment. A sample of 40 students participated in the study, who were randomly assigned to teams to complete a multi-phased creative ideation activity using peerScholar, a leading online peer assessment platform. An interactive survey was distributed to participants to measure the degree to which online peer assessment was perceived to support team-level creative thinking. Analysis of the quantitative data showed that in general, teams felt creative thinking was supported by online peer assessment. To gain a deeper understanding of the processes teams used during the activity that may have led to the quantitative results, content analysis of the captured interactive dataset showed that participants most often provided supportive, suggestive, or problem-identifying feedback on their teammate’s ideas. After online peer assessment, ideas became more refined or more clearly communicated, were withdrawn or combined, or entirely new ideas were generated. From this analysis, two frameworks were introduced: the first outlining the various forms of feedback participants used as they commented on their teammate’s ideas, the second summarizing the potential effects feedback might have when online peer assessment is used as an interface to facilitate the sharing and evaluating of ideas in teams. The results of this thesis expand the literature by exposing that online peer assessment could be an effective means of supporting creative thinking within teams. New avenues of exploration in creativity research are discussed that are expected to benefit postsecondary educators in their efforts to support groupwork and creative skill development in students.

abstract: M.Ed.


title: Remembering the Duvalierist State – Gender, State Repression, and Migration Patterns between Haiti and Canada

contributor:
Little, Margaret
Political Studies

subject:
Haiti
Haitian Feminism
Haitian Diaspora
Duvalier dictatorship
Anti-racism
Black Activism
Memory Studies

abstract: This dissertation explores Haitian feminism from a transnational perspective, examining the intergenerational memory of political violence perpetrated under the Haitian dictator Jean-Claude Duvalier (1971–1986) and the ways in which it shaped Haitian men and women’s experiences in the diaspora in Montreal from the 1960s to 1980s. Drawing on scholarship centring Duvalierism, the memory of political violence, and epistemologies of ignorance as they relate to migration, diaspora, and citizenship, this dissertation develops an analytical framework that centres memory and experience within the context of displacement and racial violence. Using a decolonial feminist ethnography and life stories of former political prisoners in Haiti, two generations of Haitian migrants in Montreal, and Haitian feminists based in Montreal, this research co-creates a repository of narratives – centring Haitian women’s experiences – that work to gender and trouble Duvalierist, Quebec, and Cold War historiographies. Drawing from these accounts as well as archival research, my findings shed light on the production and transmission of narratives on the dictatorship and what they reveal regarding gendered experiences of repression, migration, and transnational citizenship. The analysis unearths complex individual and collective memorial mechanisms that illuminate how Haitians experienced and remember political violence under Duvalier, and how those lived experiences have shaped resistance strategies to the regime in Haiti and to systemic racism in Montreal. These narratives and my research debunk the broadly adopted working hypothesis of political amnesia on the thirty-year-long dictatorship.

abstract: PhD


title: Exploring Isoform-specific Roles of Calpain-1 and Calpain-2 in Breast Cancer Metastasis Promoting Cellular Functions

contributor:
Greer, Peter
Pathology and Molecular Medicine

subject: Breast Cancer

subject: Calpain-1

subject: Calpain-2

subject: Cell Migration

subject: Cell Invasion

abstract: Breast cancer (BC) is the most diagnosed cancer among Canadian women. Among the breast cancer subtypes, triple-negative breast cancer (TNBC) exhibits the poorest survival outcome, likely due to its heterogeneity and lack of defined therapeutic targets. Detection of localized BC at an early stage often leads to a curative outcome. However, disease progression to metastatic dissemination is the major cause of high mortality rates, underscoring the value of novel approaches targeting the metastatic process. Calpain proteases have emerged as potential novel therapeutic targets in TNBC, due to their involvement in regulating cell migration and invasion, two processes required for the metastatic potential. This thesis explored independent and non-redundant roles of calpain-1 and calpain-2 isoforms in cellular functions promoting TNBC metastasis. Using a panel of capn1, capn2, and capns1 CRISPR-Cas9 genetic knockout (KO) and lentiviral rescue MDA-MB-231 human TNBC cell lines, cell migration and invasion were investigated in vitro. Absence of either calpain-1 or calpain-2 reduced the migratory potential of MDA-MB-231 cells, where calpain-2 disruption had the greatest effect in reducing the average speed. Calpain-2 was also identified as the dominant isoform regulating the invasive potential of MDA-MB-231 cells. Collectively, our observations suggest isoform-specific roles of calpain-1 and calpain-2 in BC metastasis, and provide insights on calpain proteases as novel targets that may be applied alone or synergistically with conventional therapies to treat metastatic BC.

abstract: M.Sc.


title: Biooxidation and Thiocyanate Leaching of Refractory Gold Ore in One-Step

contributor:
Ghahraman, Ahmad
Ramsay, Juliana
Mining Engineering

subject:
Gold
Thiocyanate
Biooxidation
Refractory ore
Leaching

abstract:
Gold is among the precious metals and for more than a century, it has been extracted by the cyanidation process. Cyanide is highly toxic for humans and living organisms. Moreover, with increasing gold extraction over time, the average gold grade in minerals has decreased and simultaneously cyanide usage increased. Consequently, using non-cyanide reagents for gold extraction from low-grade ores has attracted attention. Among different reagents, thiocyanate has been selected as the promising alternative to cyanide. Compared to cyanide, thiocyanate is less toxic to humans and aquatic organisms, and safer for the environment. First, a feasibility study on gold extraction from an oxide ore by thiocyanate leaching was conducted. After a series of experiments designed by the response surface methodology, the optimum condition for maximum gold recovery, 96%, from an oxide ore has been identified: 500 mM thiocyanate, 100 mM ferric iron, and 50% pulp density at 25 °C and pH 2 for 24 h.
In addition to environmental issues and high cyanide consumption, sometimes cyanide leaching is not technically or economically feasible; it is generally done in alkaline media, so the acidic oxidation slurries should be neutralized before cyanide leaching which often adds to the complexity of the process. Consequently, a sustainable method for gold extraction from low-grade refractory ore was developed by combining acidic biooxidation (a mixture of Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans) and acidic thiocyanate leaching in one system to avoid neutralization and minimize the complexity of the process. Furthermore, thiocyanate leaching requires ferric iron as an oxidant for gold extraction and this can be provided by microorganisms during ore biooxidation. It was found that in-situ leaching by 0.2 M thiocyanate of the biooxidized ore in the presence of bacterial culture and no ferric iron addition resulted in the highest gold recovery, 86.9%. Finally, for selective gold extraction from thiocyanate PLS, anion exchanger resins were tested. For selective gold adsorption from synthetic and real PLS, 100 g/L MTA5011 resin at pH 2 for 24 h adsorbed 99% gold. Then a mixture of 0.01M thiourea with 1M sulfuric acid selectively eluted 70.1 % gold from loaded resins.

abstract: PhD


title: EEG-based Brain Computer Interface with Deep Learning

contributor:
Etemad, Ali
Electrical and Computer Engineering

subject:
EEG
Brain Computer Interface
Deep Learning
Semi-Supervised Learning
Riemannian Metrics Learning
Capsule Network
Long Short-Term Memory
Biosignal Processing

abstract: Electroencephalogram (EEG)-based Brain Computer Interfaces (BCI) are very important and have been widely used in multiple application domains, ranging from human-computer interaction to medical and biomedical applications. To overcome the challenge of EEG representation learning, we propose a Long Short-Term Memory (LSTM) network with an attention mechanism to learn the importance of EEG information varying through time, where discriminative information with higher importance is assigned higher scores to better contribute to the classification performance. Our model significantly outperforms the state-of-the-art solutions for hand movement classification. Moreover, we provide a generalized solution for various BCI applications by effectively learning EEG representations. Our solution learns spatial information (Riemannian mean and distance) from spatial covariance matrices on a Riemannian manifold. It also learns the temporal information via EEG features extracted from signals in consecutive time periods in Euclidean space. Finally, we use an effective fusion strategy to combine the spatial and temporal information. Our method performs excellently in all the experiments (emotion recognition, motor imagery classification, and vigilance estimation), approaching the state-of-the-art results in one dataset (SEED) and considerably outperforming the best results of existing works in the other three datasets (BCI-IV 2A, BCI-IV 2B, and SEED-VIG), setting a new state-of-the-art result. We then tackle the problem of multimodal learning and propose an architecture composed of a capsule attention mechanism following a deep LSTM network for multimodal EEG and Electrooculogram (EOG) learning. Our model learns hierarchical dependencies in the data through the LSTM and capsule feature representation layers. Experiments show that our model is robust to noise and capable of identifying correlated and independent information existing in EEG and EOG. Moreover, the robustness of our method is demonstrated by outperforming other solutions and baseline techniques, setting a new state of the art in vigilance estimation dataset (SEED-VIG). Finally, to overcome the challenge of shortage of labeled training data, we propose a novel semi-supervised architecture for learning reliable EEG representations. Our model uses pairwise representation alignment to reduce the potential distribution mismatch between large amounts of unlabeled data and a limited number of labeled data. The study shows that our approach obtains strong results, outperforming other methods in the majority of few-labeled experimental conditions across multiple emotion recognition datasets (SEED, SEED-IV, SEED-V, AMIGOS).

abstract: PhD


title: The Metallogenesis of the Mesoproterozoic Morro Agudo Zn-Pb Sulfide District and Vazante-Paracatu Mineral Belt: Evidence from Mineralogy, Geochemistry, and Sulfide Mineral Chemistry

contributor: Geological Sciences and Geological Engineering

subject:
Geochemistry
Metallogenesis
Mineral Chemistry of Sulfide Minerals
Sediment-hosted base metal deposits
Zinc sulfide ore
Zinc silicate ore
Carbonates

abstract: The Vazante-Paracatu Mineral Belt is a Proterozoic carbonate-siliciclastic basin with two distinct styles of base metal mineralization (sulfide and silicate). The Lapa and Morro do Calcário formations host Zn-sulfide deposits (Morro Agudo, Ambrósia, Fagundes) and occurrences in the northern part of the belt, and the Serra do Poço Verde Formation hosts hypogene Zn-silicate deposits (Vazante and North Extension) and occurrences in the southern part. Mineralization at the Morro Agudo district is stratigraphically controlled within dolomite lenses and structurally controlled by a steep normal fault. The genesis of the Morro Agudo district has been interpreted as MVT, SEDEX, or Irish-type. The Vazante Group dolomitic rocks experienced multiple generations of hydrothermal carbonate precipitation, silicification, and overprinting by several generations of pyrite, sphalerite, and galena. Mineral chemistry of sphalerite reveals mixing of Fe and Cd-rich endmembers, and the earlier generations are enriched in Co, Cu, Ge, Hg, Pb, and Tl, with lower Mn and Fe compared to the last generation. Fluid temperatures calculated from trace element composition range from 82–320°C (mean ~200–250°C), which is consistent with previous fluid inclusion studies. Galena mineral chemistry indicates low Cu and Mn and high Ag, Cd, and Se contents in the initial galena phase. Low Fe, In, and Mn in sphalerite are similar to compositions of other global MVT deposits, and the high estimated temperatures of formation suggest a higher geothermal gradient in the Neoproterozoic or high advective heat flow during the Brasiliano Orogeny. The Vazante-Paracatu district is characterized by As-Ag-Cd-Cu-Fe-Hg-In-Mn-S-Sb-Se-Tl±Ge-Mo-Re-Te, with Zn-silicate ore more enriched in Ag, Cu, In and Se and poorer in Mn and Tl than Zn-sulfide ore. Geochemistry of the siliciclastic units reveals that the Serra do Garrote Formation has the highest contents of ore-related elements and has potential to be the major contributor of metals during hydrothermal fluid flow. Host rocks of the sulfide ore and the overlying phyllite-bearing Canastra Group may have contributed to the local enrichments of some metals. Ore fluid temperatures are similar throughout the Vazante Group, suggesting an extensive, circulating hydrothermal, metalliferous fluid event with distinct precipitation mechanisms for Zn-silicate and Zn-sulfide ore.

abstract: PhD


title: Decentralized Learning in Stochastic and Mean-Field Games

contributor:
Yuksel, Serdar
Mathematics and Statistics

rights: Attribution-ShareAlike 3.0 United States

subject:
game theory
multi-agent systems
reinforcement learning
stochastic games
mean-field games

abstract:
Multi-agent reinforcement learning (MARL) is the study of strategic interaction between multiple learning agents that coexist in a shared environment. Compared to single-agent theory, MARL theory is plagued by several inherent challenges, including decentralized information and non-stationary feedback, the latter of which arises when agents adapt their behaviour in the course of learning.

This thesis is concerned with decentralized MARL in stochastic and mean-field games, with three primary objectives: (1) to identify structural properties of games that are useful and relevant to MARL; (2) to exploit observed structure and inform algorithm design; (3) to describe the emergent behaviour in a system when all agents use subjectively justified algorithms.

We begin our study in the context of stochastic games with independent learners, agents who do not observe the actions of other agents. We study sequences of joint policies obtained by updating each agent's policy according to some policy update rule. Restricting our attention to update rules of the so-called epsilon-satisficing type, a natural class of update rules arising frequently in MARL, we define a structural property for games, which we call the epsilon-satisficing paths property. We prove that symmetric games and two-player games have this property, and we observe that this property has desirable consequences for algorithm design.

To study MARL in a setting with greater decentralization, we study partially observed N-player mean-field games. In this setting, learning agents have only a partial view of the system, and may not appreciate the importance of strategic interaction. Agents in mean-field games may, therefore, naively resort to use of single-agent learning algorithms. We investigate the use of naive single-agent algorithms in mean-field games, and we give sufficient conditions for their convergence. We subsequently develop a theory of subjective equilibrium based on each player's using naively learned estimates to evaluate their performance.

Finally, we develop a subjective analog to our epsilon-satisficing theory and prove several structural properties of mean-field games within this framework. These structural results are then used to design decentralized MARL algorithms for N-player mean-field games, and the convergence behaviour of these algorithms is rigorously analyzed.

abstract: PhD


title: Exploring Self-Regulation Among Surgical Residents During the Period of  Competency-Based Medical Education Curricular Implementation

contributor:
Chahine, Saad
Pyper, Jamie
Education

subject:
CBME
Competency-Based Medical Education
Obstetrics and Gynecology
Surgical Residency
Post-graduate Medical Education
Self-Regulated Learning

abstract:
Introduction
Competency based medical education (CBME) is being implemented in residency training programs across Canada. CBME, as opposed to a time-based model, involves the progression through residency based on attainment of competencies fundamental to practicing as an independent physician. The proposed advantages of CBME include greater accountability, a more learner-centered approach that allows students to progress at their own pace, and social relevance. In order to ensure that the proposed advantages of CMBE are being realized, the experiences of key stakeholders such as residents should be examined. This study uses the theoretical framework of self-regulated learning to explore the nature of self-regulation for residents in OBGYN during this period of curriculum change.
Methods
In this qualitative case study two residents who trained in the traditional residency curriculum participated in a focus group. Six residents who trained in the CBME curriculum participated in focus groups and three residents participated in individual interviews. Data was analyzed using a constant comparison analytic strategy. Open coding and an inductive approach were used to identify themes and develop the big ideas.
Results
Analysis of the responses from the non-CBME residents revealed that Senior OB/Gyn Residents demonstrate awareness of the complex and cyclical nature of their learning, and how SRL aspects are valuable. Constructive feedback with an overt personalized nature was perceived to be most helpful. The quality of feedback received from staff is critical to learning. For the CBME residents OB/GYN Residents are experienced learners who apply aspects of SRL, are aware of expectations and feel the need to adapt. Many facets of feedback were perceived to be incongruent or not inter-related. SRL is appreciated, but the increase in self-efficacy and feelings of independence is not felt to be consistently an outcome of CBME.
Conclusion
The two big ideas which emerged from this research are: the theoretical underpinnings and proposed benefits of CBME align with resident reported preferences for an education system which would aid in SRL, however, in this study the practical implementation of CBME has not consistently demonstrated these benefits. SRL provides insight into this discrepancy between proposed and actual practice.

abstract: M.Ed.


title: Biogenic Thiosulfate Production for Gold Leaching

contributor:
Ghahreman, Ahmad
Mining Engineering

subject: Gold Leaching Biohydrometallurgy Hydrometallurgy Bio-oxidation Thiosulfate Sulfur

abstract:
At the present time, the average grade of gold in deposits being mined is decreasing, and the prevalence of feed components that negatively impact the cyanidation process, is increasing. Thiosulfate is an alternative lixiviant that is often suggested as a cyanide replacement. There are many challenges associated with the implementation of thiosulfate gold leaching, most prevalently the high consumption of reagents during leaching, increasing the cost. The literature of the past two decades has focused on the use of additives and solution conditions to slow decomposition of the reagent. Alternatively, biogenic production of thiosulfate is another path towards the development of feasible thiosulfate gold extraction methods. In this study, the design of a biogenic thiosulfate leaching method has been developed for the first time.
First, a comprehensive study of the literature from many disciplines was conducted to identify potential microorganisms. The bacterium Methylophaga sulfidovorans was selected for laboratory study. Different substrates were used to produce biogenic thiosulfate and evaluated based on yield and conversion efficiency. Sodium sulfide was determined to be the most effective with biogenic thiosulfate (Bio-TS) production reaching a maximum of 1.9 g/L in testing. Next, the viability of Bio-TS gold leaching was tested using leaching experiments on oxide ore where maximum gold extraction of 62 % after 24 h at 10% pulp density in a stirred tank system was obtained. In the final research chapter, the effect of solution conditions and additives were explored with respect to gold extraction efficiency, Bio-TS consumption, and effects on other solution components during leaching. Gold leaching efficiency was increased by 66 % and copper precipitation decreased by 40 % with the addition of 10 mmol/L ethylenediaminetetraacetic acid (EDTA) and 0.1 mol/L ammonia due to coordination reactions with copper ions in solution. The kinetics of the system were modelled using the shrinking core model and determined to be limited by diffusion to the gold surfaces in the ore particles (R2 > 0.994). Additionally, the thermodynamics of the system were modelled to determine the reduced stability zone of the aqueous copper complexes. Finally, the potential and limitations of this method were summarized.

abstract: PhD


title: A Systematic Study of the TESS Photometry of the Magnetic O-type Stars

subject:
astronomy
stellar magnetism
massive stars
TESS photometry
O-type stars

abstract: Large spectropolarimetric surveys have revealed that a relatively rare sub-population (<10%) of massive O-type stars possess detectable photospheric magnetic fields. There are many open questions surrounding the magnetic fields of O-type stars, including their origin, impact on stellar evolutionary paths and role in observed O star spectral and photometric variability. However, the small number of known magnetic O stars has significantly hindered our understanding of their global properties. Only eleven Galactic magnetic O stars have been confirmed, and another six magnetic candidates have been identified in the Magellanic Clouds. Recent high-precision photometry obtained by the Transiting Exoplanet Survey Satellite (TESS) is providing significant advancements to the fields of massive star magnetism and asteroseismology. Diverse variability has been seen in the TESS light curves of O-type stars, offering an unprecedented opportunity to study their physical properties. We have performed a systematic analysis of the  TESS light curves of the known magnetic O stars and extra-galactic magnetic candidates to characterize their variability and search for signatures of rotational modulation due to co-rotating magnetospheres. We perform custom light curve extractions in order to investigate systematics related to the detrending process and search for contaminating signals from blended sources. We detect a variety of signals in the TESS light curves of the Galactic magnetic O stars, including rotational modulation, stochastic low-frequencies and possible coherent low-frequency pulsations. We detect rotational modulation in two of the extra-Galactic magnetic candidates. These results have important implications for understanding the origins of O star photometric variability and will help inform future searches for new magnetic O star candidates using TESS photometry.

abstract: M.Sc.


title: A Global Analysis of Scalar Dark Matter-neutrino Interactions at the 1-loop Level

subject:
Physics
Astroparticle Physics
Neutrinos
Dark Matter

abstract:
One of the biggest challenges of modern physics is the identification of a missing component of the Universe, Dark Matter (DM). In particular, we do not know how it interacts with the Standard Model (SM). In this thesis, we consider a model of real scalar DM coupled to the SM via a 1-loop level neutrino portal. The model contains interaction terms that can generate neutrino masses, another open question in physics.

We perform a global analysis and find that this model can reproduce the observed relic abundance of DM and is consistent with observations from Big Bang Nucleosynthesis, the Cosmic Microwave Background, the Lyman-alpha forest, and the mass of the lightest neutrino.

abstract: M.Sc.


title: Bugging Out: Protest Music, the Vietnam War and the American Counterculture

contributor:
Dubinsky, Karen
History

subject:
Protest music
Vietnam War
Music history
Countercultural history
American history
Cultural history

abstract:
By the 1960s, music and musicians in the United States yet again assumed new roles in the production of culture and the geopolitical Cold War, as music became an avenue of political expression and musicians cultural icons. As rock and roll traversed the radio waves and emanated throughout the bedrooms of American youth in the 1960s, a new power, analyzable through rock and roll and underpinned by youth anti-war and countercultural movements, redefined notions of citizenship, patriotism, and democracy in the United States. The technological, cultural, and demographic changes of the post-World War II era helped facilitate the emergence of a rock music genre that expressed a skepticism of American imperialism, anti-draft sentiments and an understanding of citizenship that emphasized disobedience.
To ascertain a better understanding of the cultural transformations that shaped the United States in the 1960s, this thesis evaluates the influence of rock and roll music on the anti-Vietnam and anti- imperial discourses of the American anti-war and countercultural movements. Despite the historical complexity of conceptualizing, defining and analyzing a movement as far-reaching and multifaceted as the American countercultural movement of the 1960s, this thesis contends that an historical analysis of music provides a window through which historians and other academics alike may begin to discover new linkages, insights and discontinuities that would further nuance our understanding of such a recent and pivotal period of American political, social, and cultural history. Music simultaneously and paradoxically bridged and divided elements of the countercultural movement, providing, as an art, a means through which messages of frustration, rebellion, or refusal could be communicated despite the pressures of censorship and, in some instances, marketed to the popular mainstream.

abstract: M.A.


title: Characterization of the REE fluorocarbonate minerals and REE release at Earth’s surface conditions of the T-Zone of the Nechalacho Deposit, Northwest Territories, Canada

subject:
Rare Earth Elements
Release Rates
Geochemistry

abstract:
There is limited knowledge regarding the behaviour of naturally occurring bastnaesite [REE(CO3)F] and parisite [Ca(REE)2(CO3)F2] during mineral-fluid interaction. Bastnaesite and parisite comprise the rare earth element (REE) ore of the T-Zone at the Nechalacho Deposit, located in the Northwest Territories, Canada. This study characterizes the bastnaesite and parisite at this location and investigates the dissolution rates of bastnaesite and parisite at near Earth’s surface conditions.
Analysis of the ore minerals of the T-Zone by electron microprobe analysis (EMPA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), indicated that the minerals are enriched in light rare earth elements (LREE). Bastnaesite and parisite are intergrown with each other and with fluorite and quartz as determined by scanning electron microscopy (SEM).
Batch dissolution experiments were performed with a mixture of bastnaesite, parisite, fluorite and quartz in water to evaluate the effects of pH and grain size on the solubility of the REE minerals.  Experiments were run at pH 2, 4 and 9 with three differing starting percentages of bastnaesite, parisite, quartz and fluorite. The dissolution of bastnaesite and parisite is largely pH dependent, with more REE released at acidic conditions than at alkaline conditions. In pH 2 conditions, precipitation of a lanthanide (Ln) fluoride phase is evident through X-ray diffraction (XRD) and SEM analysis. At an initial pH 4, the solution was neutralized within ~60 h to a pH of 7-8, exhibiting that bastnaesite and parisite can neutralize moderately acidic solutions but not highly acidic (pH 2) solutions.
Mixed flow through dissolution experiments containing bastnaesite, parisite and quartz were performed at pH 2, 4 and 8.6 conditions. Results revealed that at pH 8.6 the release rate of total REE and Ca is likely non-stoichiometric whereas the release rate of total REEs and Ca at pH 4 is closer to stoichiometric. Formation of LnF3 was evident at pH 2, illustrating the ready dissolution of bastnaesite or parisite followed by the rapid precipitation of LnF3 at low pH. Dissolution rates increased as a function of decreasing pH and were slower than calcite dissolution at the same pH conditions.

abstract: M.Sc.


title: Developing Janus Filters for Real-World Separation of Oil from Surfactant-Stabilized Emulsions

contributor:
Liu, Guojun
Chemistry

subject:
polymer
separation
commercialization
Janus Filters
demulsification
antimicrobial

abstract:
A major industrial problem that directly impacts our water quality is the difficulty in separating oil and/or water from contaminated, surfactant-stabilized, oil-in-water emulsions. Lacking the appropriate technology to separate these industrial emulsions on site, they are either sent away for tedious, expensive treatment processes, or as a last resort disposed of directly into our environment.
Janus filters, named after the Roman God of Two Faces to depict their asymmetrical structure, have shown tremendous potential as a low-cost, green alternative for rapid emulsion separation. Existing Janus filters that bear a demulsifier on one side and a hydrophobic polymer on the opposite side can break oil-in-water emulsions and selectively separate the coalesced oil. Though effective, the early generations of Janus filters were not ideal for real-world application due to the tedious syntheses of the polymers used, the troublesome fabrication protocols of the coatings as well as lack of perfect control in the structures and properties of the produced filters.
This thesis covers the development of a portfolio of Janus filters for real-world applications and focuses on integrating features to address common membrane challenges, such as biofilm formation, as well as improving the practicality and reproducibility of procedures.
First, a trifunctional Janus filter was developed that not only offers demulsification and oil separation performance but also exhibits antimicrobial activity. Hydrophobic and demulsifying polymers were synthesized via free radical polymerization and attached to opposite sides of a cotton fabric through transesterification chemistry. The demulsifying face was subjected to quaternization enhancing the demulsification capabilities, improving the o/w separation performance, and bestowing the fabric with antimicrobial properties.
Next, the feasibility of developing a multi-substrate Janus filter with a well-controlled structure, fabricated by combining glass wool and cotton fabric, through facile coating methods based on sol gel chemistry was investigated. The effect of varying the distribution of hydrophilic and hydrophobic layers within a Janus filter on the separation performance of o/w emulsions was also studied.
To broaden our understanding, the commercial viability of the portfolio of Janus filters was assessed through a case study with industrial samples and supplementary techno-economic analysis, market research and customer discovery.

abstract: PhD


title: Studies on the Biosynthesis of Nucleocidin and Related Nucleoside Analogues

contributor:
Zechel, David
Chemistry

subject:
biosynthesis
nucleocidin
glycosyltransferase
natural products
fluoronucleoside

abstract:
Natural products (NPs), also known as secondary metabolites, are compounds produced by an organism that are non-essential to its survival. These compounds are commonly biologically active and thus, are useful in the medical and pharmaceutical industries. Many pharmaceuticals, including antibiotics, are halogenated. Notably, about a quarter of the top-selling pharmaceuticals are fluorine-containing compounds. Fluorine is a small element which does not sterically hinder drug-receptor interactions and forms a strong bond with carbon. In stark contrast to the vast number of fluorinated compounds in industrial and pharmaceutical use, there are only six known naturally occurring fluorinated NPs, and one known enzyme capable of fluorination.
This work is focused on elucidating the biosynthesis of nucleocidin, a nucleoside which contains rare 4’-fluorine and 5’-O-sulfamoyl substituents. The biosynthetic pathway to formation of these two groups remains unknown. Nucleocidin was first discovered in cultures of S. calvus in 1956. Production by this organism was extremely low, thus the first goal of this project was to enhance production. Through a 16S rRNA genome mining approach, improved producers, with an approximately 30-fold increase in nucleocidin production, were identified. The increase in production helped to facilitate gene disruption experiments and identify genes which are needed for fluorination and sulfamate formation. NucG, nucI and nucJ, encoding two sulfatases and a radical SAM enzyme, respectively, and are essential for sulfamate formation, but have no effect on fluorination. Preliminary work towards the characterization of NucG and NucI revealed that NucG can function as a phosphodiesterase, while NucI can function as a sulfatase, phosphatase and phosphodiesterase. The exact catalytic role of NucG and NucI in nucleocidin biosynthesis is unknown. NucK, nucO and nucN, encoding two sulfotransferases and an amidinotransferase, respectively, are required both for sulfamation and fluorination. Disruption of nucP, encoding a DNA topoisomerase, produced a new unknown fluoronucleoside, while disruption of orf208, encoding a lycopene cyclase, had no effect on the fluoronucleoside profile. Additionally, two new acetylated nucleocidin derivatives were identified in culture extracts of wild type S. virens and S. aureorectus.
Key genes within the nucleocidin cluster were used to guide genome mining for the discovery of novel glycosyl and sulfamate containing nucleosides, including 3’-O-β-glucosyltubercidin. The substrate scope and kinetic parameters were determined on the glycosyltransferase, AvpGT, responsible for glucosylating tubercidin. Following the logic that new nucleocidin derivatives may be discovered through searching for clusters containing nucleocidin homologs, preliminary work towards in vivo rational design of an amino acid nucleocidin analogue was performed by introducing genes from the biosynthetic gene cluster encoding the related 5’-O-sulfamated nucleoside, ascamycin. Work towards characterization of this natural product and the biosynthetic enzymes is presented here.

abstract: PhD


title: Design, Modelling and Experiments of a Multi-Lobe, Swirl Bend Mixing Nozzle for a Turbo-Fan Engine

contributor:
Birk, Albrecht Michael
Mechanical and Materials Engineering

subject:
Mixing nozzles
Computational Fluid Dynamics

abstract:
The design, numerical simulation, and experimental testing of a mixing nozzle is presented in this project. The motivation behind this research is reducing the IR signature of a turbofan engine and measuring backpressure data. IR signature reduction was be done by (1) blocking the line of sight to the turbine; and, (2) reducing the plume temperature of the exhaust jets.
The nozzle design methodology describes nozzle construction parameters and how optical blockage was integrated into the design; this was done using available CAD software. Later, the designed nozzle was numerically tested on the turbofan engine using ANSYS products, and experimentally in the Gas Turbine Lab at Queen’s University where cold flow experiments were conducted.
Various nozzle geometries were tested under cruising altitude engine parameters. The nozzle models were tested under various inlet swirl conditions (0°, 20°, -20°) to mimic real engine environment.
RANS CFD simulations using the k-epsilon turbulence model predicted lower backpressure for the engine with the designed nozzle compared to the rounded nozzle case. Also, the increased mixing between the bypass and core engine exhaust resulted in a reduced temperature of the core jet. Pressure losses, backpressure, blockage, and flow features were the parameters of interest.
Later, the designed nozzle was 3D printed, mounted on a ducted fan, and tested in the low-speed wind tunnel. The ducted fan produced a high-speed swirling jet. A Seven-hole probe was used to take velocity and pressure data. Two load cells were used to measure thrust produced by the fan. With the swirling nozzle attached to the fan, the measured thrust produced by the fan was higher than the thrust measured with a rounded nozzle.

abstract: M.A.Sc.


title: Force-Myography Based Estimation of Energy Absorption Capabilities of the Human Arm for Robotic Tele-Rehabilitation Therapy

contributor:
Hashtrudi-Zaad, Keyvan
Electrical and Computer Engineering

subject:
Robotics
Teleoperation
Rehabilitation
Upper-arm
Force myography
Remote therapy
Excess of Passivity
Passivity
Stability
Telerehabilitation

abstract:
The need for rehabilitation therapy has been significantly increasing in the last few decades, due to neurological disorders caused by stroke. The cost of therapy for such a wide variety of motor impairments is high and the availability of therapists is insufficient for the current demand.

Therapists could perform remotely, using teleoperated robots that allow patients to receive help at home. This can reduce costs of transportation and increase availability of therapists.

Therapeutic forces delivered by a robotic system can help improve therapy by providing unlimited neurological stimulation to patients, taking maximum advantage of the plasticity of the brain for a timely recover from partial or total loss of kinesthesia, proprioception, and somatosensation.

Telerobotic therapy should be safe and easy to perform by therapists and patients, and this remote interaction must be realistic enough for therapy to work. Hence, a proper control system needs to be developed. Some controllers have been designed to achieve safe interactions, with a trade-off between stability and performance. Techniques such as damping and scaling degrade the interaction forces and the effectiveness of the therapy. In addition, instability can be induced from the active nature of the therapist and communication delays, injecting energy into the robotic rehabilitation system and  generating unexpected harmful forces.

In this work, improved interpolations of energy absorption capabilities of the human arm are estimated through upper-arm Force-Myography. This approach by itself relaxes stability conditions that affect performance in robotic rehabilitation systems.

A new method for estimating energy absorption capabilities is implemented, using recursive least squares. This method allows adaptive behaviour of the estimation, providing valuable information according to the patient's real-time muscle contractions and energy absorption capabilities.

A fast orthogonal search is developed for estimating time-series EOP profiles that represent real-time energy absorption capabilities of the human arm.

A novel controller is also developed to allow safe delivery of therapeutic energy to the human arm, with real-time estimation of upper-arm energy absorption capabilities. In addition, a new kinematic scaling approach is implemented to reduce therapist's effort while delivering therapy. These methodologies are successfully tested in a teleoperation setup with two robotic devices.

abstract: PhD