VictorJuiz/thesis huggingface dataset:
Bang-Bang Practical Stabilization of Rigid Bodies

In this thesis, we study the problem of designing a practical stabilizer for a rigid body equipped with a set of actuators generating only constant thrust. Our motivation stems from the fact that modern space missions are required to accurately control the position and orientation of spacecraft actuated by constant-thrust jet-thrusters. To comply with the performance limitations of modern thrusters, we design a feedback controller that does not induce high-frequency switching of the actuators. The proposed controller is hybrid and it asymptotically stabilizes an arbitrarily small compact neighborhood of the target position and orientation of the rigid body. The controller is characterized by a hierarchical structure comprising of two control layers. At the low level of the hierarchy, an attitude controller stabilizes the target orientation of the rigid body. At the high level, after the attitude controller has steered the rigid body sufficiently close to its desired orientation, a position controller stabilizes the desired position. The size of the neighborhood being stabilized by the controller can be adjusted via a proper selection of the controller parameters. This allows us to stabilize the rigid body to virtually any degree of accuracy. It is shown that the controller, even in the presence of measurement noise, does not induce high-frequency switching of the actuators. The key component in the design of the controller is a hybrid stabilizer for the origin of double-integrators affected by bounded external perturbations. Specifically, both the position and the attitude stabilizers consist of multiple copies of such a double-integrator controller. The proposed controller is applied to two realistic spacecraft control problems. First, we apply the position controller to the problem of stabilizing the relative position between two spacecraft flying in formation in the vicinity of the L2 libration point of the Sun-Earth system as a part of a large space telescope. The proposed position controller represents the first feedback strategy to guarantee the accuracy level required by this class of space missions using real-life electric thrusters. The final controller is applied to the control of a large space vehicle performing rendezvous and docking operations with the International Space Station. It is shown that the controller guarantees a safe docking even under the effects of biases in the placement of the on-board thrusters.

Keywords: Attitude Control
Bang-Bang Control
Double-Integrator Control
Spacecraft Control
Advisor: Maggiore, Manfredi
Damaren, Christopher J
A Comparison of Full-Day and Half-Day English and French Immersion Kindergarten: Children's Outcomes and Experiences

The purpose of this research was to examine kindergarten children’s outcomes and experiences in four program models: full-day French immersion, half-day French immersion, full-day English, and half-day English. This quasi-experimental study employed a mixed methods approach. Child participants (N=70) across the four programs were administered standardized measures of English receptive vocabulary and reading, as well as a print task, a number sense task, a drawing task, and an interview, at the beginning and end of kindergarten, as well as at the beginning of Grade 1. Additionally, children from French immersion (FI) programs were administered equivalent measures in French. Parents of child participants completed questionnaires at the beginning and the end of kindergarten, which served to provide demographic information and parents’ perspectives of their children’s experiences. Finally, in order to provide context for the study, educators (N=7) across the four programs participated in semi-structured interviews relating to program implementation and child experiences. Mixed ANOVAs were conducted in order to determine program differences at each time point. Results revealed significant differences in English word identification, with children from English full-day kindergarten (FDK) scoring significantly higher at the beginning of Grade 1 than children in either FI program, and English word decoding, with only children from half-day programs (FI and English) making significant gains over the kindergarten year. However, when analyzing French literacy skills, only children from FI FDK kindergarten made significant gains in word identification scores, and scored significantly higher in receptive vocabulary than children from half-day FI kindergarten. When examining drawing complexity, results revealed only children from FDK programs (both English and FI) made significant gains between time points. Children’s interview transcripts revealed that across all programs, play was discussed more frequently at the kindergarten level, but academics were discussed more often in Grade 1. This study makes important contributions to the literature on full-day kindergarten programming as well as second-language education. Findings suggest that FDK has a greater impact on reading in second-language contexts and that increased exposure to the second language, as well as learning through play, is beneficial for vocabulary development and word identification in the second language. In the context of education in Ontario, this study has particular relevance as school boards decide whether to offer FI at the kindergarten level with the emergence of the new play-based FDK program.

Keywords: French immersion
Kindergarten
Play-based learning
Advisor: Pelletier, Janette
High-quality constraints on the glacial isostatic adjustment process over North America: The ICE-7G_NA (VM7) model

The Glacial Isostatic Adjustment (GIA) process describes the response of the Earth's surface to variations in land ice cover. Models of the phenomenon, which is dominated by the influence of the Late Pleistocene cycle of glaciation and deglaciation, depend on two fundamental inputs: a history of ice-sheet loading and a model of the radial variation of mantle viscosity. Various geophysical observables enable us to test and refine these models. In this work, the impact of the GIA process on the rotational state of the planet will be analyzed, and new estimates of the long-term secular trend associated with the GIA process will be provided. It will be demonstrated that it has undertaken a significant change since the mid-1990s. Other important observables include the vast amount of geological inferences of past sea level change that exist for all the main coasts of the world. The U.S. Atlantic coast is a region of particular interest in this regard, due to the fact that data from the length of this coast provides a transect of the forebulge associated with the former Laurentide ice sheet. High-quality relative sea level histories from this region will be employed to generate a new model of the GIA process that includes for the first time data from the forebulge region in its optimization process (the ICE-6G_C (VM6) model). Then, the series of analyses is extended to include space-geodetic observations of present-day vertical uplift of the crust. A solution reconciling all available data from the continent, named ICE-7G_NA (VM7), is obtained through modest further modifications of both the viscosity structure of the model and the North American component of the surface mass loading history. It provides an excellent fit to the constraining data related to the GIA process, including observations of the time-dependent de-levelling of the Great Lakes region. Finally, to test the global exportability of the new model, its predictions of relative sea level change are tested against observations from the Western Mediterranean region.

Keywords: Climate change
Geodesy
Glacial isostatic adjustment
Mantle viscosity
Paleoclimate
Sea level evolution
Advisor: Peltier, W. Richard
AN INTEGRATED GEOCHRONOLOGICAL, PETROLOGICAL, GEOCHEMICAL AND PALEOMAGNETIC STUDY OF PALEOPROTEROZOIC AND MESOPROTEROZOIC MAFIC DYKE SWARMS IN THE NAIN CRATON, LABRADOR

The Nain craton comprises the western, Labrador segment of the larger North Atlantic craton (NAC) which exposes Early through Late Archean gneisses. The NAC is bounded on all sides by Paleoproterozoic collisional orogens that involved either considerable structural reworking (Torngat-Nagssugtoqidian-Lewisian) or the accretion of juvenile arc magmas (Ketilidian-Makkovik). The NAC remains poorly understood compared to other Archean crustal blocks now dispersed globally. Compounding this problem is a lack of reliable paleomagnetic poles for NAC units that predate its assembly into the supercontinent Laurentia by ca. 1800 Ma, which could be used to test neighboring relationships with other cratonic fragments. In order to understand the history of the NAC as part of a possible, larger supercontinent, the record of mafic dyke swarms affecting the craton, particularly those that postdate the Late Archean terrane assembly, were examined in this study. Diabase or gabbroic dyke swarms are invaluable in such studies because their geometries offer possible locus points, they often have a punctuated emplacement and precisely datable crystallization histories, and they have cooling histories and oxide mineralogy amenable to recovering robust paleopoles. Coastal Labrador exposes a number of mafic dykes, some of which are demonstrably Paleoproterozoic (e.g. 2235 Ma Kikkertavak dykes; 2121 Ma Tikkigatsiagak dykes) or Mesoproterozoic (e.g. 1280-1270 Ma Nain and Harp dykes) in age (U-Pb; baddeleyite or zircon). The southern half of the Nain craton (Hopedale block) in particular preserves a rich array of mafic dykes. Dyke cross-cutting relationships are numerous and relatively well exposed, permitting multiple opportunities for paleomagnetic field tests (e.g. baked contact). The results presented here allow understanding of the tectonic evolution of the NAC with implications for strengthened Labrador-Greenland correlations, and testing possible Paleoproterozoic supercontinent reconstructions.

Keywords: Geochemistry
Geochronology
Labrador
Mafic Dyke Swarms
North Atlantic Craton
Paleomagnetism
Advisor: Hamilton, Michael A.
Nanostructured Microelectrodes for High-Activity Electrochemistry in Biosensing and CO2 Recycling

Electrochemical biosensors are promising candidates for point-of-care (POC) diagnostics, since they require neither costly instrumentation nor expert operators. However, for them to become widely used in a clinical setting, biosensors must be enhanced in sensitivity without increasing costs or compromising the speed of detection. The goal of this thesis is to realize this vision by promoting high-activity redox reactions via rational design of the size, shape and structure of electrodes. Incorporating nanostructures on the surface of microelectrodes greatly increases their surface area and reaction rates, while maintaining efficient diffusion of analytes to electrode surfaces. Here, by coupling optimized electrode morphology with an enzyme-based assay, I report on a new class of ultra-sensitive biosensors. I showcase the applicability of these sensors for POC diagnostics by incorporating them on a platform designed to isolate rare cells in biological samples. The integrated device is the first example of an electrochemical sensing platform capable of detecting cancer cells with clinically-relevant sensitivity and specificity. Decreasing the cost of POC diagnostic devices is vitally important for their adoption in low-resource settings. To that end, I advance a strategy to decrease the costs associated with the fabrication of nanostructured microelectrodes (NMEs). I present an image-reversal soft lithography (IRSL) technique based on an elastomeric stamping protocol, eliminating the need for costly photolithographic fabrication steps. The distinct morphology of the sensors made by IRSL improves access to the surface of the electrodes leading to enhanced performance in the detection of biomolecules. Overall, the strategies presented in this thesis can guide the development of low-cost, sensitive, and rapid diagnostic systems. Outside of biosensing, NMEs have potentially important applications in CO2 recycling. Realizing efficient CO2 conversion to chemical fuels is an important step towards reducing the atmospheric concentration of CO2 and decreasing the carbon footprint of energy. Recently, our group reported highly-efficient electroreduction of CO2 to CO using nano-sharp Au structures. Here, I improve upon the performance of these structures by increasing the density of honed needle-like features on the surface of NMEs and demonstrate a 15-fold improvement in the reaction rates relative to the previously reported best results.

Keywords: Biosensing
CO2 Electroreduction
Electrochemistry
Lab-on-chip
Microfabrication
Nanostructured Microelectrodes
Advisor: Sargent, Edward H
Kelley, Shana O
Maternal Effort, Food Quality, and Cortisol Variation During Lactation in Propithecus coquereli in Northwestern Madagascar

The duration and quality of the infant care mothers provide is paramount to investigating life history theory. Maternal care is the principal determinant of infant survival and future reproductive success. Lactation is the most energetically expensive activity for mammals, in turn causing lactating females to compensate for drastically greater energy requirements. Lemur reproduction occurs under strict seasonal parameters to cope with harsh climatic conditions. I evaluated maternal behavioral care-giving effort towards infants over 26 postnatal weeks in Coquerelâ s sifaka (Propithecus coquereli) (n=10 infants, n=10 lactating females). Secondly, I evaluated the nutritional quality of foods consumed exclusively by lactating females (n=10). Lastly, I examined stress responses across sex and reproductive classes in earlier (weeks 1-12) versus later lactation (weeks 13-24) (n=10 lactating females, n=19 adult males, n=8 non-lactating adult females). I conducted fieldwork over two consecutive birth seasons (2010 and 2011) in Ankarafantsika National Park located in northwestern Madagascar. Earlier lactation occurs during the austral winter, and coincides with the seasonally driest time of the year. I quantified maternal care-giving by measuring infant transport position, carrier identity, and bodily contact. Nutritional food quality was measured by protein, fiber, energy (n=123), and mineral content (n=119). I quantified stress responses to determine how sex and reproductive classes respond to seasonal pressures and lactation by measuring cortisol variation in two lactation stages in lactating females (n=180), adult males, (n=133), and non-lactating adult females (n=62). Infants were more altricial relative to other lemurs of similar body size. Allomaternal care was documented, although mothers were the primary infant transporters. Lactating females most frequently selected foods high in non-protein energy, and regularly selected foods high in available protein and fiber. Lactating females had lower cortisol relative to adult males that approached statistical significance, and significantly lower cortisol than non-lactating adult females. Adult males had significantly higher cortisol during the earlier lactation stage in comparison to the later stage. Understanding the behavioral, nutritional, and endocrinological responses of lactating females provides a comprehensive view of how maternal energetics, infant care, and infant development are dynamically performing during the most energetically constraining time of year in a stochastic environment.

Keywords: Lactation
Lemurs
Life history
Madagascar
Maternal care
Nutritional ecology
Advisor: Lehman, Shawn M
Founding Speech: Aristotle's Rhetoric as Political Philosophy

There is notoriously little agreement in the literature on Aristotle’s Rhetoric. While disputes about most every aspect of Aristotle’s argument abound, most scholars tend to agree on one general point. That is, most read the work as an attempt at discovering and describing the nature of rhetorical persuasion. The present study takes a different view: it maintains that the Rhetoric is better understood as an attempt at replacing the existing teaching and practice of rhetoric with one that is better suited for use within the deliberative institutions of political society. The Rhetoric, on this reading, is a work with a political project. This dissertation contributes to the literature in three distinct ways. First, it attempts to show that there is a significant rhetorical component to some of Aristotle’s most prominent arguments. It argues, among other things, that the first chapter of the work and the taxonomy of rhetoric presented in chapters two and three should not be taken at face value. Second, this study illustrates the extent to which concerns about legislation figure into Aristotle’s attempts at articulating an art of speech. Most readings conceptualize the problem of rhetoric as consisting in the relationship between rhetoric and collective judgment, taking the view that Aristotle’s solution lies in liberating judgment from a rhetorical practice that enmeshes it in some incongruous or inappropriate way. This study suggests that preserving the rule of law, protecting a state’s legislative institutions, and cultivating civic virtue, are among Aristotle’s chief concerns. Third, the present work also locates, what it considers to be, Aristotle’s non-rhetorical teaching about the nature of rhetorical persuasion.

Keywords: Aristotle
Rhetoric
Advisor: Orwin, Clifford
Balot, Ryan
The Dynamic Interplay of Epigenetics and Genetics in Selected DNA Mismatch Repair and Wnt Signaling Pathway Genes in Colorectal Cancer

Colorectal cancers (CRC) undergo distinct genetic and epigenetic alterations, contributing towards chromosomal instability (CIN), microsatellite instability (MSI), and/or epigenetic instability (CpG island methylator phenotype). Two major pathways disrupted in CRC include upregulation of Wnt signaling and deficiency in DNA mismatch repair (MMR). MLH1, a MMR gene that corrects DNA replication errors, is frequently lost in CRC due to promoter CpG island hypermethylation leading to the MSI phenotype. A single nucleotide polymorphism (SNP, rs1800734) in the MLH1 promoter is associated with MLH1 CpG island hypermethylation, decreased expression, and MSI in tumours. In this thesis, a novel association was discovered between variant SNP genotype and MLH1 CpG shore hypomethylation in normal tissues of CRC cases and control individuals, specifically in peripheral blood mononuclear cells and normal colon. Interestingly, no SNP-associated differences in methylation were observed in tumour DNA at the MLH1 shore. Chromatin immunoprecipitation studies of histone modifications in CRC cell lines revealed that the MLH1 shore may be a poised enhancer. The transcription factor AP4 was shown to bind only at the MLH1 promoter in wildtype and heterozygous cell lines but not in homozygous variant carriers of rs1800734, demonstrating a functional consequence of this polymorphism. To further explore epigenetic events between CRC subtypes the methylation status of two genes involved in Wnt signaling were assessed. Methylation of ITF2, a Wnt target gene, and APC, which inhibits Wnt signaling and is frequently mutated in CRC, was measured in two CRC patient populations. Both genes incurred tumour-specific methylation, with APC methylation occurring equally across CRC subtypes while ITF2 methylation was associated with MSI tumours. This thesis has investigated the functional epigenetic regulation occurring at key genes involved in DNA MMR and Wnt signaling, two pathways often dysregulated in CRC. This work provides insight into the regulation of CpG shores, how DNA variants play a role in epigenetics, and the contributions of DNA methylation to CRC subtypes and cancer susceptibility.

Keywords: Colorectal Cancer
Epigenetics
Methylation
Mismatch repair
Single nucleotide polymorphisms
Advisor: Bapat, Bharati
Image-based localization for mobile and vehicular applications

We study the image-based localization problem in mobile and vehicular applications. The problem can be stated as `given a query image at an unknown location with some side information available regarding the camera and environment, how can one estimate the camera location with respect to a reference coordinates frame?'. The side information could be the query (or database) camera parameters, database of location-tagged images and/or measurements of some 3D dimensions. The problem has been well investigated in a number of literature works proposing methods for indoor and outdoor applications. We focus on the localization accuracy and complexity in this thesis and propose methods to improve them. Some of the proposed methods increase the location recognition rate, while others improve the (fine) localization accuracy. We also propose a robust and accurate method for outdoor scenarios. The majority of the image-based localization methods can be classified into two categories, i.e. landmark-based (e.g. logo-based) and image retrieval-based methods. We propose a semi-supervised formulation for the logo-based problem, which results in a considerable decrease in the median and variance of the localization error compared to the state-of-the-art, at the cost of adding controllable computational complexity. For the image retrieval-based approach, we propose an Epipolar geometry-based method to refine the localization estimate. The proposed method demonstrates greater accuracy, higher robustness to database locations sparsity as well as demonstrating extrapolation capability. For the indoor scenarios with no textured landmarks and/or repeated scenery, where both category of methods fail to localize the user accurately, we propose two localization methods utilizing OCR, called OCRAPOSE I and OCRAPOSE II. The proposed methods improve the localization accuracy, provide simplified training (i.e. side information acquisition) and lower localization complexity. For outdoor applications, we propose a two-dimensional robust localization method using the Google street view database, called 2DTriPnP. 2DTriPnP simplifies the complicated full 3D pose estimation by converting it to a 2D practical one and proposing a fast robust estimation method. It will be demonstrated in experiments that 2DTriPnP provides the great accuracy required in a number of outdoor scenarios such as safety in vehicular networks. Furthermore, it outperforms the 3D version in terms of the localization accuracy and complexity.

Keywords: Computer vision
Image
Indoor mobile applications
Localization
Signal processing
Vehicular application
Advisor: Valaee, Shahrokh