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A Hybrid Neuroevolutionary Approach to the Design of Convolutional Neural Networks for 2D and 3D Medical Image Segmentation
Get PDFThis thesis highlights the development and evaluation of a hybrid neuroevolutionary approach for designing Convolutional Neural Networks (CNNs) for image classification and segmentation tasks. We integrate Cartesian Genetic Programming (CGP) with Novelty Search and Simulated Annealing algorithms to optimize the CNN architectures efficiently.
The challenge lies in reducing the computational demands and inefficiencies of traditional Neural Architecture Search (NAS) techniques. To address this, a flexible framework based on CGP is utilized for evolving network architectures. Novelty Search facilitates the exploration of varied architectural landscapes, promoting diversity of solutions. Simulated
Annealing further refines these solutions, optimizing the balance between exploring new possibilities and exploiting known good solutions within the search space.
Our experiments, conducted on benchmark datasets such as DRIVE and MSD, demonstrate the method’s effectiveness in generating competitive segmentation models. On the DRIVE dataset, our models achieved Dice Similarity Coefficients (DSC) of 0.828 and 0.814, and Intersection over Union (IoU) scores of 0.716 and 0.736, respectively. For the MSD dataset, our models exhibited DSC scores up to 0.924 for the Heart task, showcasing the potential of our method in handling complex segmentation challenges across different medical imaging modalities.
The significance of this research lies in its hybrid approach that efficiently navigates the search space for CNN architectures, thus reducing number of fitness evaluations while achieving near state of art performance. Future work will explore enhancing the algorithm’s effectiveness through advanced data preprocessing techniques, and the exploration of more complex network layers. Our findings highlight the potential of evolutionary algorithms and local search in advancing automated CNN design for medical image segmentation, offering a promising direction for future research in the field
Matching Mechanisms Design for Crowd-Sourced Delivery Under Supply Side Uncertainty
Get PDFCrowd-sourced delivery services represent an innovative urban logistics solution that has garnered considerable attention in recent years due to its superior economic, environmental, and social benefits. Distinct from conventional freight transportation, the crowd-sourced delivery model employs ordinary people as either a supplement or an alternative to professional delivery personnel, integrating them into the delivery process. Due to the inherent uncertainties associated with these non-professional participants, manifested in their strategic refusal of orders, aiming for obtaining better matching outcomes. Furthermore, the prevalent issue of frequent order refusals leads to challenges such as repeated matching and delivery failures, posing significant challenges for the current state of crowd-sourced delivery services.
Addressing these challenges, this dissertation introduces sophisticated matching mechanisms and compensation schemes for crowd-sourced delivery systems, aiming to optimize outcomes in complex scenarios. The research begins with an empirical investigation into the determinants of driver decisions via a series of stated preference surveys. This foundational work enables the development of an accurate predictive model for driver behavior. Integrating this model into an advanced optimization framework, the study then assesses various matching and compensation strategies, considering factors like acceptance probability and decision-making processes. Further innovation is demonstrated through the proposal of an order-postponement mechanism, informed by the urgency value of deliveries. This approach aims to increase the efficiency of crowd-sourced delivery, accommodating more orders within given time windows. A key contribution of this dissertation is the introduction of the concept of reinforced matching stability. Building on this notion, a novel algorithm is proposed, demonstrably reducing order refusal rates to as low as 1\% and achieving operational cost savings of up to 18\%. This research not only addresses the immediate challenges of crowd-sourced delivery services but also contributes significantly to the broader discourse in urban logistics and transportation planning
Bridging Worlds: Skill Development and Conceptual Thinking in Art Institutions
Get PDFThis thesis investigates the relationship between skill development and conceptual thinking by analysing their role in two modern-day art institutions: one in India and the other in The United States. This study relies on qualitative research methodologies, which include reflections of the author's artistic experiences in these institutions, artwork analysis, and in-depth interviews with professors from these institutions. The goal of this research is to critically evaluate and compare two prestigious art programmes to determine their strengths and weaknesses and to create the best possible environment by combining these elements into an art curriculum that incorporates the best of different educational paradigms
Transcending Beyond the ‘Detectable’: Queer Mourning, Memory, and Futurity in Eric Rhein’s Lifelines
Get PDFTurning toward the past while propelled by a desire for futurity, this thesis explores the intersections of art and memory in the artwork of American artist and writer, Eric Rhein (b. 1961). Diagnosed with HIV in 1987 at the age of twenty-seven, Rhein’s survivorship affirms the endurance of queer love as well as the perseverance required to navigate a life-changing diagnosis in both a socially and epidemiologically tumultuous terrain. The first section evaluates the importance of the past through lineages of queer representation, contributing to Rhein’s inclination toward self-documentation while additionally laying the foundational framework for activist forces that later permeated the united confrontational response to the AIDS crisis. The second chapter investigates the transformative powers of queer love enlivened through collective manifestations of mourning and activism, highlighting the significance of vulnerability, social contingency, community, and proximity. Finally, the closing chapter draws upon the speculative potentials of queer world-making, both embodied and ephemeral, emphasizing the (non)linearity of queer temporalities. Converging with the contemporary era of undetectability, this thesis critically (re)considers memories versus histories as resistive modalities present in curatorial and institutional settings, permitting the development and bridging the excluded within a utopian architecture saturated with possibility, belonging, and care. Focused centrally on the preservation and celebration of those lost to AIDS-related complications, Rhein’s body of work exists as a living archive, transcending disseminated narratives of loss, proliferating and expanding much like our ever-evolving relationship to HIV and AIDS
Unraveling the Socioeconomic Layers Leading to Materialism: Exploring the Mediating Role of Happiness and Moderating Influence of Gratitude on Materialism
Get PDFIn a world where consumption is becoming increasingly accessible with online retailers, where social media influencers equate material possessions to happiness, convenience, or success, and where shopping has been proven to boost our mood, it is no wonder that consumers are struggling to control their buying behaviour. This research examines the impact of social classes on materialism, focusing on the mediating role of happiness and the moderating role of gratitude. An experimental research design was implemented, and two online surveys were utilized to collect data. In study 1, an unexpected, though interesting, effect of perceived social class on materialism was found. It was also found, as predicted, an effect of perceived social class on happiness, which in turn, predicted materialistic values; however, the mediating effect of happiness was not found to be significant. In study 2, as predicted, an effect between perceived happiness and gratitude was found. Additionally, gratitude had an effect on materialism. However, the moderating effect of gratitude was not found to be significant. The findings of this study will provide valuable insights into how different social classes impact happiness levels, how happiness plays a role in materialism, and how practicing gratitude can influence your materialism levels. This study also offers practical implications for marketers to effectively target and position marketing messages, and for consumers to make more thoughtful purchase decisions that may enhance their well-being, as well as society’s
Elucidating the Structure and Dynamics of Short Cyclic Antimicrobial Peptides Using Molecular Dynamics
No full textTruncated host-defense peptide derived from chicken angiogenin 4 (mChAng-4, c-(CRFKFRIVIC)) is a membrane active peptide displaying antibacterial properties. The structural properties of mChAng-4 are related to its function and aggregation properties. The cyclic nature of mChAng-4 makes its structure more constrained and stable compared to its linear analog. We study the structure and dynamics of single mChAng-4 peptides in solution as well as multi-chain mChAng-4 systems comprising eight peptides to investigate their aggregation. To investigate the effect of hydrophobicity on the structure, we study the native mChAng-4 (c-(CRFKFRIVIC)) and a valine substituted analog (c-(CRFKFRVVVC)). We compare the L and D configurations of the peptides as D-peptides are known to be more stable in a biological context due to a lack of D-specific peptidases. We compare the inverted sequence in L and D form (c-(CIVIRFKFRC)) to address differences between L and D enantiomers. An alanine scan revealed which residues were essential toward folding. We increase the rigidity of the peptide by replacing the disulfide linkage with an amide bridge. The analysis of the 500 μs ensemble of single peptide simulations shows that single peptides in solution display varying degrees of β sheet formation. Oligomerization was investigated in a 36 μs ensemble of the native, double valine mutant, linear, Dab, Dap, and native systems. The analysis of the 36 μs ensemble of aggregation systems suggested the linear, Dab, and Dap were more likely to aggregate in solution, but further analysis is needed to draw conclusions about the oligomerization states
Mineralogical Mythmaking and the Roots of the Canadian Mining Industry in Colonial Tanganyika: The Williamson Diamond Mine (1940-1958)
Get PDFIn the 1980s the Canadian mining industry began a process of global expansion, transforming into a world-leading industry that tapped into mineral resources on virtually every continent. Many scholars associate this development with the economic changes brought about by Structural Adjustment, which opened large swathes of the planet to foreign investment, but there is a much longer history of Canadian mining abroad. This thesis explores the Imperial roots of the mining industry through an analysis of a lesser-known mining project undertaken by a McGill geologist in the late 1930s, the much-mythologized Williamson Diamond Mine of Tanzania. The Williamson Diamond Mine provided invaluable industrial material during the Second World War, eventually becoming one of the most technologically advanced schemes in British Africa. The mine hosted a unique community of Canadian and European experts tasked with operating that technology while supervising the much larger African workforce, a situation reflected in the segregated, racial division of labor and associated investment in security of the mine, which still haunts contemporary Canadian mining projects. By locating the origins of Canada’s global mining industry in colonial Africa —and the life trajectory of Williamson himself —this thesis also aims to draw attention to the unstable yet durable transnational connections that linked different sites within the British Empire, Canada and Tanzania, through decolonization and past the Cold War period. In the process, this work sets out to make a contribution to Canadian Global History that highlights the importance of further study into Canada-Africa relations
Exploring the Luminescence Dynamics of Lanthanide-Doped Nanoparticles: Exploiting the Temporal Dimension for Diverse Applications
Get PDFLanthanide luminescence at the nanoscale has garnered considerable attention over the last few decades, with research on ternary fluoride nanoparticles focusing heavily on upconversion and to a lesser extent on radioluminescence. However, these nanomaterials have not yet been implemented commercially. This is likely, in part, due to the overwhelming emphasis on demonstrating potential applications, rather than understanding the fundamental mechanisms that drive these luminescence phenomena. As a result, the forbidden nature of the lanthanide 4f-4f transitions has hindered the widespread implementation of such nanoparticles.
To shed light on the complex nature of lanthanide-doped upconverting nanoparticles, studies on co-doped Yb3+ and Tm3+ nanoparticles were completed with varying host composition (including LiYF4, NaGdF4, and BaYF5) and activator dopant concentration (ranging from 0.1 to 2.0 mol%). The interionic spacing and site symmetry of the lanthanide ions was deemed to play an integral role in the relative intensity of each Tm3+ emission, indicating that different combinations are optimal for different applications. With the addition of an active shell doped with Tb3+, the energy transfer across the core/shell interface was evaluated next, establishing that a radiative energy transfer mechanism from the 1D2 excited state of Tm3+ was most prominent.
Influences known to affect the upconversion efficiency of nanomaterials were then evaluated on LiLuF4:Eu3+ radioluminescent nanoparticles. The results herein indicated that a greater material density and effective atomic number improved the efficiency of the radioluminescence process, while varying the dopant concentration was not as influential, when compared to direct ultraviolet excitation. Furthermore, the addition of Gd3+ as a sensitizer or employing core/shell structures did not prove advantageous to the radioluminescence intensity.
While luminescence lifetimes are measured to evaluate nonradiative energy transfer efficiencies between spectroscopically active species, proof-of-concepts herein demonstrate that they can also be employed to add a temporal component to various applications. These include upconversion nanothermometry, particle velocimetry, and covert information storage, all taking advantage of the long-lived excited state decay times of various lanthanide ions
Dessiner l’écoute: Cartographies d’entretiens autour de la vie et l’œuvre de Jean-Paul Riopelle
Get PDFCe mémoire de maîtrise explore l’interface entre l’histoire orale et la cartographie alternative. La pensée visuelle y est utilisée comme outil d’écoute, d’archivage, d’analyse et de diffusion d’entretiens qualitatifs. Le cas d’étude, le projet "Raconte-moi Riopelle" (2021-2023), réunit 21 récits autour de la vie et de l’œuvre de l’artiste Jean-Paul Riopelle (1923-2002). La méthodologie originale de recherche-création repose sur un inventaire graphique du corpus et des processus d’analyse cartographiques inspirés de la cartographie sensible et de la visualisation inductive. Sur le plan du contenu, la recherche met en lumière, d’une part, l’homogénéité des participant.e.s au projet, principalement liés aux sphères artistiques. D’autre part, la recherche révèle six thèmes qui traversent les récits. Les quatre premiers concernent un portrait en nuances de Riopelle, concernant sa personnalité, son sens de l’humour, ses liens amicaux, et sa relation au temps. Les deux autres thèmes s’articulent autour de la création et du regard, véritables fils conducteurs des récits. Sur le plan méthodologique, la recherche confirme l’efficacité de la pensée visuelle à traiter des matériaux d’histoire orale. D’abord, les annotations graphiques ont optimisé l’écoute et favorisé la mémorisation des récits. Ensuite, la spatialisation des données a facilité leur analyse. En complément du processus d’analyse, une série de collages photographiques exprime la complexité sensible du corpus. Ces images offrent un point d’entrée plus personnel vers le corpus. En somme, ce mémoire ouvre la voie à de nouvelles façon d’aborder le traitement et la diffusion de données en histoire orale notamment à partir de nouvelles formes cartographiques inspirées de l’écoute
Asking the “Overwhelming Question”: Or, Why Do Poets Fail at Difficult Conversations?
Get PDFT. S. Eliot’s declaration that “poets in our civilization, as it exists at present, must be difficult” owes something to the experience of art the poet championed, one in which anxiety around poetry’s difficulty would be transformed into an “authentic” relationship between reader and text. This thesis argues Eliot’s pronouncement that poets should enact a difficulty of the most authentic order really means that poets should try to enact poems in the model of dynamic, informal speech between reader and text—something for which we might use “conversation” as a shorthand. At the same time, I also consider the way conversation is always a problem for poets, at least those working in the proto-professional literary landscape in which Eliot was invested, a time when critics were developing strict methods to judge poetry based on its properties rather than its effects. This is not just because the proto-professional poet’s formal expertise comes at the expense of their ability to engage in informal, affective speech, but also because to authentically represent such speech means to fail to do so, since success in conversation means ceding formal authority in favour of spontaneity itself. In linking developments in modern literary criticism to extraliterary forms of communication difficulty, I argue our contemporary obsession with difficult conversations speaks as much to a desire for “authentic relationships” as it does to an anxiety around the increasing professionalization of artmaking in industrial modernity, and the kinds of interpersonal communication it seems to foreclose