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Generalized Hilbert's Tenth Problem
No full textThe aim of this work is to retrace the path to the solution of the classical Hilbert's Tenth Problem and the attempts trying to generalize it reaching, finally, a new result concerning its extension in number fields. First we deal with the classical case classifying diophantine functions as the recursive ones, using the diophantinity of the exponential as a key tool. In order to generalize the unsolvability of the diophantine problem to rings of integers of number fields the line is to simulate the core of the classicl proof, which seems to be more natural in the setting of totally real number fields as shown by the work of Denef and Lipshitz. After that few attempts were done to reach a general result, Pheidas was able to use the Elliptic Curves to obtain a new criteria which, in its generalized version of Shlapentokh, is the key together with the new additive combinatorics techniques of Pagano-Koymans to the proof of the general case
Implementing Lean Manufacturing in a High-Mix Low-Volume Environment with Sequence-dependent Changeover and Alternative Routing
No full textThis thesis explores the development of a Lean manufacturing system at company ABC that operates in a tailored to a high-mix, low-volume manufacturing environment characterized by sequence-dependent changeovers and alternative routing. To achieve this, a methodical approach was followed to identify the key sources of waste and their root causes, which is demonstrated through the system's current value stream map. Because of the variability in cycle times at the batch processes, sequence-dependent changeover times, and alternative routings in Assembly processes, it’s challenging to create pull sequence at the pacemaker with generic lean guidelines. In order to address these challenges, a new scheduling method, "concurrent scheduling," has been developed. The method consists of controlling the pacemaker through a schedule while simultaneously coordinating the downstream batch process with a product wheel, and introducing a sequential pull system between the two processes. The schedules and the product wheels are offset by a delay to enable the pacemaker to supply the batch process efficiently. The batch process is the pivotal point of the value stream to determine the lowest possible production interval, also known as Every-Product-Every-Interval (EPEI), and the optimization model also aims to minimize the EPEI. Once the pacemaker scheduling and EPEI is determined, the quantities of the finished goods supermarket and the necessary work-in-progress of the First-In-First-Out lanes have been determined to achieve a lean flow. The study results have been summarized into a future state map, providing the company with a framework to improve its production system.
The results indicate significant improvements, including a 58.2% reduction in total production lead time, total control and predictability over inventory levels, a standardized value stream and management, improved production flexibility, and greater expected customer satisfaction. While the individual solutions and the methodology's application can assist manufacturers facing similar problems in achieving operational excellence, this thesis provides insights into the overall application of Lean in High-mix, Low-volume environments
Repairing socioecological relationships: Landguaging the imperial L2 classroom
No full textThis two-manuscript dissertation explores how two imperial and non-Indigenous languages in Canada (English and French) can resist replicating monolingual and colonial traditions though plurilingual pedagogies and online tools. In Chapter 1, an overview of the ecolinguistic framework that all chapters are rooted in is presented. It explores how multimodal and plurilingual activities build learners’ relationships to their nested macro- to micro-sized socioecosystems. This framework is then extended to a discussion of ecological technologies and pedagogies.
Chapter 2 (Manuscript A) focuses on the struggles that language learners experience when engaging with speakers of different language varieties. This difficulty is often explained by a lack of exposure to sociophonetic variability in classroom materials with the emphasis instead on teaching the (usually invariable) standard variety. Focusing on the French second language (FSL) context, our understanding of sociophonetic variation in the classroom comes primarily from textbook studies; little empirical evidence has quantified the amount and kind of social speech markers (e.g., age, race, region, native speaker status) found in FSL audiovisual curriculum. Using a comparative case study, this chapter examines the audiovisual materials of two FSL classroom contexts: the university and the government sponsored francisation course. Interviews and questionnaires elicited FSL instructors’ criteria for selecting materials, and their experiences with and attitude towards including social speech marker variation in their curriculum. Additionally, audiovisual materials from each instructor collected over a semester were categorized and analysed by five social speech markers and clip length. Results showed that instructors held positive viewpoints towards including variation; however, audiovisual materials from both settings were invariant across the markers of age, race, region, native speaker status and sourced mostly from mass media. Specifically, the materials excluded elderly, adolescent, children, racialized, non-native speakers and varieties from regions other than Québec. Suggestions for incorporating more varied materials in the curriculum are highlighted and form the basis of the second manuscript.
To address the lack of variation found in the imperial L2 curriculum in Chapter 2, Chapter 3 (Manuscript B) introduces Parlure Games, a computer-assisted language-learning tool that promotes exposure to and interaction with those speakers absent from audiovisual materials (e.g., elderly, racialized) using non-mass media and online mapping. Parlure Games has three teaching goals: exposure to sociophonetic variation, development of plurilingual competencies, and opportunities to visualize and critically discuss imperialism’s territorial expansionism. Following a four-level chronological framework, Manuscript B reports on the first three stages: (1) the development of Parlure Games in alignment with high variability phonetic training (HVPT) methods; (2) an exploration of its pedagogical affordances based on ecolinguistic principles; and (3) its suitability for achieving the three teaching goals, as evaluated through the Technology Assessment Model-2 (TAM2). While the first two levels are conceptual and design-oriented in scope, the third is empirical: Drawing on TAM-2-informed data, seventeen undergraduate TESL teacher candidates rated Parlure Games highly, suggesting strong adoption intentions. Based on these findings and user feedback, we provide a revised model for the tool’s in-classroom implementation, preparing it for deployment for the final stage of the adopted chronological framework.
In the final chapter, the main findings of each manuscript are reviewed, and the value of plurilingual ecolinguistic tools for enhancing the teaching and learning of imperial languages ecologically is reaffirmed. The studies’ limitations are outlined, followed by a set of plurilingual ecopedagogical, Landguaging activities that address the entanglement of language and land in imperial language teaching contexts, repairing imperialism’s sociecological relationship with land
Brain Vascular and Metabolic Biomarkers in Age-Related Diseases
No full textDuring aging, accumulating cerebral vascular and metabolic dysfunction significantly contributes to cognitive decline and neurodegenerative diseases. Identifying early cerebral biomarkers linked to age-related conditions like Alzheimer’s disease (AD) and coronary artery disease (CAD), and modifiable factors like cardiorespiratory fitness, is crucial for disease understanding and prevention.
This thesis comprises five interrelated studies using multimodal neuroimaging, including dual-calibrated functional magnetic resonance imaging (fMRI), and advanced computational modeling. Manuscript One investigated cognitively healthy older adults with familial AD risk, showing that decreasing cerebrospinal fluid amyloid-beta—a marker of amyloid accumulation—was associated with increased cerebral blood flow (CBF), particularly among individuals with higher cardiovascular risk. Elevated baseline inflammation predicted faster longitudinal declines in CBF within this group, highlighting cardiovascular health as a critical mediator of early cerebrovascular changes.
Manuscript Two extended this investigation to severe vascular impairment in CAD, revealing widespread cerebrovascular and metabolic dysfunction characterized by decreased CBF, cerebrovascular reactivity (CVR), cerebral metabolic rate of oxygen consumption (CMRO₂), and elevated oxygen extraction fraction (OEF). Notably, CVR and OEF were directly associated with cognitive deficits, emphasizing their role as early markers of cerebrovascular compromise.
Manuscripts Three and Four explored how cardiorespiratory fitness (VO₂peak) influences cerebral physiology in healthy aging and CAD. In healthy older adults, higher fitness correlated positively with greater CBF and negatively with OEF, suggesting enhanced oxygen delivery efficiency. Among CAD patients, higher fitness uniquely improved CMRO₂ in addition to CBF and CVR, underscoring fitness’s potential to reverse metabolic dysfunction clinically.
Manuscript Five addressed calibrated fMRI limitations to estimate metabolic biomarkers, including poor arterial spin labeling signal quality and breathing manipulation dependency. It introduced a robust deep learning-based computational model, providing accurate, gas-independent estimates of CBF, CVR, OEF, CMRO₂, and mitochondrial oxygen diffusivity directly from fMRI data, enhancing biomarker reliability and clinical application.
Collectively, these studies reveal the complex interplay between vascular, metabolic, and fitness-related factors influencing cerebral health during aging and cardiovascular disease. Integrating longitudinal data, advanced neuroimaging, and computational modeling, this thesis provides novel insights for early detection and targeted interventions to maintain cognitive function and reduce neurodegenerative risk
Effects of ocean warming on the behaviours of an invasive predator and native keystone prey
No full textBoth climate change and invasive species are threatening coral reef ecosystems globally. These two stressors are often studied singularly despite co-occurring in nature. For reef fishes, ocean warming due to climate change leads to elevated metabolic rates, which can increase feeding rates. Invasive species can also cause major declines in abundance and even extinctions in native prey through predation. Here, we examine the effects of ocean warming on the behaviours of an effective invasive predator, the Indo-Pacific lionfish (Pterois spp.), and their prey, native parrotfish (Scarus iseri and S. taeniopterus), which are keystone herbivores on Caribbean coral reefs. We hypothesized that warming would increase both lionfish predatory behaviours and parrotfish foraging behaviours but would decrease parrotfish anti-predator behaviours. To test this, lionfish and parrotfish were placed in experimental mesocosms heated to 32 °C or 29 °C. Lionfish hunted significantly more at 32 °C than those at 29 °C, but only at midday. Lionfish at 32 °C also rested less and spent more time near parrotfish at midday. Although some parrotfish anti-predator behaviours like sheltering did not differ between temperature treatments, parrotfish activity levels (i.e., feeding, hovering, and swimming behaviours) increased at elevated temperatures. We also examined the effect of temperature on various growth metrics in lionfish and parrotfish but found no difference between treatments. Our findings suggest that climate change can potentially exacerbate the negative, predatory effects of invasive lionfish on native keystone prey, through warming effects on both predator and prey, which could lead to cascading impacts in coral reef ecosystems
Contested Reproduction: Abortion Debates in Postrevolutionary Mexico City (1930-1940)
No full textIn the aftermath of the Mexican Revolution of 1910-1920, the question of abortion became a cause of worry in the intellectual circles of Mexico City. Many reasons explain the heightened concern about women's reproductive functions: Mexican authorities' project to reconstruct and modernize the nation, the rise of eugenics, and a generalized concern about the country’s population decline. However, historiography does not stress enough how diverse the discourses on abortion were in the period from 1930 to 1940. Highlighting this period of diversity is the objective of this thesis. Even if the Catholic Church – which continued to exert much influence on social mores despite the post-revolutionary government's anticlerical stance – was strictly antiabortionist, more moderate positionings permeated the publications of the period. Demands for changes in the laws of abortion were relatively common among legal and medical professionals, and more radical propositions for the legalization of abortion had some traction amongst Mexican thinkers, especially in the 1930s.
Factors such as university autonomy, the spread of anti-capitalist and feminist ideologies, and the government’s professed anticlericalism contributed to the relative freedom of individuals to express divergent opinions on abortion policies. However, these conditions began to change by the end of the decade. I posit that by the end of the 1930s, both the Ley General de Población of 1936 and the end of the Lázaro Cárdenas administration marked a shift to a more unitarian discourse on the question, with strict pronatalist positioning becoming the norm among Mexican institutions
A Resurrection Model Inspired by Quantum Intelligence Theory & the Urantia Book
No full textIn this article, we propose consciousness or Quantum Intelligence as a fundamental quantum entity, not reducible to classical brain function. Quantum Intelligence is the source of life and the brain and DNA are instruments or receptors of this intelligence. Quantum Intelligence enters at conception and survives after death. Accelerated photons at conception (sperm–egg fusion) curve spacetime and admit Quantum Intelligence into the embryo, similarly, the final cellular “spark” at death allows Quantum Intelligence to exit into a storage region. In the presented model, the individual’s intelligence remains free even after death thus death and it is treated as a transition, not an annihilation. This quantum framework explains immortality or life beyond death. The paper proposes a resurrection model inspired by the Urantia Book (A spiritual revelation that is meant to unite religion and science) by accelerating photons or neural interfaces that could transfer Quantum Intelligence into a new body. The proposed model supports religious beliefs of Christianity, Islam, and Zoroastrianism in an afterlife and physical resurrection
Naming the Traces: (Re)Constructing and Irish-Canadian Family Narrative of Emigration, Place-Making, and Return
No full textThis dissertation, conceived within the research-creation stream of Concordia University’s interdisciplinary Humanities program, considers the spatial, social, emotional, and cultural journey of emigration, place-making, and return-migration that the last four generations of my maternal family have undertaken between Ireland and Montreal, Canada from the late 1920s to the present day. Drawing from the fields of Oral History and Narrative, Memory Studies, Irish Studies, and Creative Nonfiction (studio component), this project begins by reconstructing the circumstances surrounding my maternal great-grandmother Norah’s emigration from her home in County Mayo, Ireland to Montreal, Quebec where she raised my grandmother Rose as a single mother during the Great Depression. The narrative then follows the subsequent generations of my family, and their emplaced memories in Montreal: from Rose’s upbringing in a series of downtown rooming-houses, to my mother and uncles’ childhood among the laneways and cold-water flats of the working-class neighborhood of Point St. Charles in the 1950s and ‘60s. The project concludes with an essay of place that recounts my experience of visiting my great-grandmother’s home-place in Shrule parish, as the first member of my family to “return” since emigration. To recreate the life-worlds of my family’s past, I draw upon oral history interviews with family members, including the mobile methodology of the walking interview; primary sources, such as ships’ records, photographs, and memory objects; secondary sources to contextualize my family’s experiences; and on-site explorations in Montreal and Ireland. Recounted in a narrative voice that blends description, analysis, and reflection, my dissertation situates itself at the intersection of what cultural historian Annette Kuhn calls “memory work”; “intimate ethnography,” a term coined by Alisse Waterston and Barbara Rylko-Bauer; and creative nonfiction
Advancing Cybersecurity in Power Grids with High Penetration of Wind Energy: From Modeling to Mitigation of Cyberattacks against Wind Farms
No full textThe increasing integration of wind energy and the reliance on digital communication systems for the remote operation of wind farms (WFs) have significantly expanded the grid’s vulnerability to cyberattacks. These risks are particularly concerning for power grids with degrading system strength (SS) and high penetration of converter-based resources, where cyber-induced instabilities threaten grid stability. This thesis investigates critical aspects of cyber risks in wind-integrated power grids, focusing on attack modeling and prevention, risk management, and mitigation strategies.
The first part introduces a cyberattack model targeting SS provision to permanent magnet synchronous generator (PMSG)-based WFs. To address this, an anomalous command verification (ACV) module is proposed to detect and prevent cyber-induced converter-driven instabilities by estimating SS buffer capacity. The second part develops a cyber-informed risk management framework using Bayesian attack graphs and distributionally robust optimization (DRO) to quantify and mitigate cyber risks. This framework incorporates converter-driven stability support (CDSS) from WFs and is validated on the IEEE 118-bus system. The third part focuses on mitigating attack-induced instabilities in offshore wind farms (OWFs) connected via High Voltage Direct Current (HVDC) systems. It introduces a physics-informed iterative control (PIC) strategy based on neural networks to reduce instability magnitudes progressively.
These contributions provide an integrated approach to addressing cyber risks in wind-integrated power grids, enhancing their security and stability in the face of evolving threats
Impact Behavior of Hybrid Thermoplastic Composite Laminates and Sandwich Panels
Get PDFThis thesis explores the development, optimization, and impact behavior of hybrid thermoplastic composite laminates and sandwich panels, focusing on environmentally sustainable materials and advanced reinforcement techniques. Double-belt and compression molding lamination methods were optimized to fabricate full thermoplastic composite sandwich panels with 100% recycled PET foam cores. Analyzing the fabrication parameters and final products’ skin-to-core adhesion revealed the critical role of PET foam density and lamination approach in achieving proper bonding. Even though panels made with compression molding outperformed under flexural loads, the continuous nature of the double-belt method offers a reliable and cost-effective alternative production approach.
In the current study, a two-step compression molding method was used to impregnate the metallic mesh layers with PP resin and form a proper connection between the composite layers. Furthermore, the effect of hybridization using stainless-steel mesh layers to reinforce composite laminates and sandwich panels was investigated. Variations of mesh wire size, orientation, and stacking sequence were analyzed to evaluate the energy absorption and damage propagation mechanism of hybrid laminates under different ranges of impact energies. While composite plates show improved performance when the reinforcing metallic layer was positioned at the midplane, it is preferred to reinforce the collision-facing side of sandwich panels for enhanced impact resistance. This strategic placement of the hybrid layer effectively increased the perforation threshold under Low-Velocity Impact (LVI) loading conditions.
In addition, Shape Memory Alloy (SMA) wires were introduced as reinforcing agents of the thermoplastic composite laminates not only to improve the impact performance, but also to take advantage of their specific healing properties to recover the post-impact deformations. Repeated LVI tests demonstrated that the SMA-assisted heating recovery process can restore over 50% of the after-impact deformations, further enhancing the durability and resilience of the composite materials