VictorJuiz/thesis huggingface dataset:
Morphological Evolution of the Feeding Mechanism in Stingrays

Evolutionary transitions between ecosystems are rare, and yet in lineages that have made these transitions we observe drastic changes in their diversity and richness as they adapt to novel habitats and novel resources. The main goal of my dissertation is to examine how transitions among diets and habitats have molded the evolution of predator traits. To test hypotheses regarding how prey materials have shaped the evolution of predators, I examined predator feeding biomechanics using experimental methods and deep-time approaches. Using 3D printing, computational milling, and computed tomography scanning, I compared the biomechanical performance of jaw shape for durophagous stingrays which prey on mollusks with shells of drastically different material and structural properties. I found that all of these jaw morphologies were equally well-suited to crushing the entire breadth of prey mollusk diversity, establishing equifinality of anatomical form stemming from convergent feeding mechanics. Insectivory has evolved only once within modern sharks and rays, found within the enigmatic freshwater stingrays of South America. Using high-speed videography and computed tomography scanning I found that these freshwater stingrays use chewing motions of the jaws when feeding on prey, facilitated by a highly kinetic cranial skeleton, and that these motions are exaggerated for tougher prey like insects. Loose jaw joints, transverse jaw kinesis, passive tooth reorientation, and a hydrodynamic tongue allow freshwater potamotrygonid rays to chew in a manner similar to many mammals. I investigated how the evolution of novel feeding modes such as insectivory and molluscivory in these freshwater rays has altered the tempo of their evolution by generating a molecular phylogeny for the family and analyzing feeding trait adaptation across 40 million years of evolution. The evolution of molluscivores and insectivores in this stingray clade are relatively modern innovations, coincident with the changing nature of the Amazon basin and repeated colonization of new riverine habitats. These dietary strategies, in addition to piscivory, are representative of truly novel adaptive peaks and have contributed to shifts in the rate of both lineage and morphological evolution in these remarkable freshwater stingrays.

Keywords: Dietary Diversification
Feeding
Functional Morphology
Habitat Transition
Potamotrygonidae
Stingrays
Advisor: Lovejoy, Nathan R
Management of Squeezing Ground Conditions in Hard Rock Mines

Squeezing ground conditions can result in large scale deformation and instability of underground excavations in rock. In hard rock mines, squeezing ground conditions are often associated with the presence of dominant foliation and high stress with resulting deformation often exceeding the capacity of installed ground support. This can result in failure of ground support making the excavations non-operational. This thesis is a contribution to improved understanding of structurally defined squeezing mechanisms observed in underground hard rock mines. A comprehensive field campaign was undertaken in two mines where squeezing was a major ground control issue. This has allowed the development of a database comprised of 147 squeezing case studies. Reported information included drift configuration and orientation, deformation monitoring, rock mass characterization and the performance of ground support. The data were reviewed to identify the failure mechanisms and to quantify the influence of ground conditions, excavation orientation, and the performance of different support strategies. The distinct element method (DEM) was used to successfully reproduce the buckling mechanism resulting in squeezing and large deformations observed in mining drifts in the database. The developed methodology was implemented in 3D models and explicitly considered the role of foliation. Subsequently, a comprehensive strategy for explicitly modeling rock reinforcement using the DEM was developed and implemented in a series of 3D numerical models. The models were calibrated based on field testing of reinforcement and observations at the LaRonde Mine. They were used to investigate the impact of different reinforcement strategies and the time of installation of the support. The numerical results were in agreement with the field observations and demonstrated the practical implications of using yielding reinforcement elements. This was supported by field data where the use of yielding bolts reduced the drift convergence and rehabilitation. An analysis and interpretation of the field data and the numerical modelling investigations were used to provide tools for the assessment and mitigation of the anticipated deformation in squeezing ground. The developed strategies can be used to select optimal reinforcement options. The developed tools and procedures can be successfully used to manage large structurally controlled deformations in underground hard rock mines.

Keywords: Buckling
Rock reinforcement
Squeezing ground
Underground mining
Advisor: Hadjigeorgiou, John
Amniote Dental Histology, Development, and Variation: Perspectives From the Fossil Record

Fossil teeth provide a wealth of taxonomic and dietary information for palaeontologists, but the evolution and development of the suite of tissues that attach teeth to the jaws in amniotes remain virtually undocumented. This contrasts strongly with the plethora of studies that have documented the development of the tooth attachment tissues (the periodontium) in modern mammals and crocodilians. The literary consensus is that mammals and crocodilians possess the most complex forms of tooth attachment, because each tooth is housed within a well-defined tooth socket and is suspended by a soft ligament. By comparison, nearly all other amniotes supposedly possess teeth that are fused to the jaws by a single bone tissue. To date, however, the homologues of the dental attachment tissues across Amniota remain unresolved. This thesis represents the first large-scale, comparative study of amniote tooth histology and development. By comparing histological sections of a large sample of modern and extinct amniotes, I establish tooth tissue homology across several major amniote groups and show that even the earliest amniotes possessed the same attachment tissues as those in mammals and crocodilians, but over millions of years, evolutionary changes in the timing of tooth tissue development have produced novel ways in which teeth can be attached to the jaws. Moreover, I show that studying dental batteries and the teeth of key fossil taxa can provide new insights into our understanding of the evolution and development of teeth.

Keywords: Amniota
Dental histology
Heterochrony
Ontogeny
Periodontium
Tooth attachment
Advisor: Reisz, Robert R
High-fidelity Aerostructural Optimization of Nonplanar Wings for Commercial Transport Aircraft

Although the aerospace sector is currently responsible for a relatively small portion of global anthropogenic greenhouse gas emissions, the growth of the airline industry raises serious concerns about the future of commercial aviation. As a result, the development of new aircraft design concepts with the potential to improve fuel efficiency remains an important priority. Numerical optimization based on high-fidelity physics has become an increasingly attractive tool over the past fifteen years in the search for environmentally friendly aircraft designs that reduce fuel consumption. This approach is able to discover novel design concepts and features that may never be considered without optimization. This can help reduce the economic costs and risks associated with developing new aircraft concepts by providing a more realistic assessment early in the design process. This thesis provides an assessment of the potential efficiency improvements obtained from nonplanar wings through the application of fully coupled high-fidelity aerostructural optimization. In this work, we conduct aerostructural optimization using the Euler equations to model the flow along with a viscous drag estimate based on the surface area. A major focus of the thesis is on finding the optimal shape and performance benefits of nonplanar wingtip devices. Two winglet configurations are considered: winglet-up and winglet-down. These are compared to optimized planar wings of the same projected span in order to quantify the possible drag reductions offered by winglets. In addition, the drooped wing is studied in the context of exploratory optimization. The main results show that the winglet-down configuration is the most efficient winglet shape, reducing the drag by approximately 2% at the same weight in comparison to a planar wing. There are two reasons for the superior performance of this design. First, this configuration moves the tip vortex further away from the wing. Second, the winglet-down concept has a higher projected span at the deflected state due to the structural deflections. Finally, the exploratory optimization studies lead to a drooped wing with the potential to increase range by 4.9% relative to a planar wing.

Advisor: Zingg, David W
Enhancement of Force Feedback in Teleoperated Surgery

Providing the surgeon with force information from interactions can potentially restore the feeling of presence at the operation site. Nevertheless, despite the advantages of force feedback in teleoperated surgery, many surgical teleoperation systems lack this feature. This thesis presents novel approaches for providing force feedback that may increase the safety of surgical procedures. This thesis proposes and experimentally validates an adaptive force reflecting method for teleoperations involving stiff tissues. The proposed method estimates the parameters of the Kelvin-Voigt model of the tissue in real-time, and adaptively scales and feeds back the interaction force to the surgeon to ensure stable contact at every moment. The proposed adaptive force reflecting method can be added to existing teleoperation systems with no force feedback mechanism, and thus provide some degree of force feedback to the surgeon. The humanâ s discrimination ability is generally degraded for low-intensity stimuli; consequently, in micro-surgery excessive forces may be applied by the surgeon in order to discriminate between different tissues, and this could result in damaging delicate tissue structures. This thesis studies the discrimination ability of the human at low-intensity forces through estimating just noticeable differences (JNDs). The relationship between estimated JNDs and reference forces was then mathematically modeled. This model is employed in the design of a force feedback strategy and teleoperation control architecture that augments the force feedback based on human discrimination ability. The experimental results indicate that augmented force feedback compared to traditional force feedback significantly reduces the average applied forces to the phantom tissue, and the number of errors a subject made in discriminating between phantom tissues.

Advisor: Goldenberg, Andrew
Drake, James
Communication Lower Bounds via Query Complexity

The goal of this thesis is to prove lower bounds in communication complexity by exploiting new connections to query complexity. Our basic strategy is to first prove a general theorem stating that for a large class of communication problems F, any protocol for F can be efficiently simulated by a decision tree solving a related problem f, and then rule out efficient decision trees for f. We use this approach to resolve several open problems (some well-known): (1): We prove superlogarithmic lower bounds on the conondeterministic communication complexity of the Clique vs. Independent Set game, answering a question of Yannakakis (STOC 1988). As a corollary, this implies superpolynomial lower bounds for the Alon-Saks-Seymour conjecture in graph theory. Furthermore, we obtain near-optimal deterministic (and even randomised) lower bounds for the Clique vs. Independent Set game. As a corollary, this implies new lower bounds for the log-rank conjecture of Lovasz and Saks (FOCS 1988). (2): We show that deterministic (and even randomised) communication complexity can be superlogarithmic in the partition number of the associated communication matrix. This answers a basic question of Yao (STOC 1979), also posed by Nisan and Kushilevitz (1997). (3): We prove near-optimal randomised communication lower bounds for the recursive AND-OR tree. This strengthens the classical decision tree results of Saks and Wigderson (FOCS 1986) and Santha (RSA 1995), and answers a question of Beame and Lawry (STOC 1992). (4): We exhibit an n-variable monotone function in NP with near-maximal monotone circuit depth complexity Omega(n/log n). This improves on the previous record of Omega(sqrt(n)) proved for the perfect matching function by Raz and Wigderson (JACM 1992). (5): We exhibit an n-node graph whose independent set polytope requires extended formulations of size exponential in Omega(n/log n). Previously, no explicit examples of n-dimensional 0/1-polytopes were known with extension complexity larger than exponential in Theta(sqrt(n)).

Advisor: Pitassi, Toniann
On the integrals of the Kudla-Millson theta series

The Kudla-Millson theta series &thetas;km of a pseudoeuclidean space V of signature (p, q) and lattice L is a differential form on the symmetric space D attached to the pseudoorthogonal group O(p, q) that transforms like a genus n Siegel modular form of weight (p + q)/2. Any integral of &thetas;km inherits the modular transformation law and becomes a nonholomorphic Siegel modular form. A special case of such integral is the well-known Zagier Eisenstein series F(τ) of weight 3/2 as showed by Funke. We show that for n = 1 and p = 1 the integral of &thetas;km along a geodesic path coincides with the Zwegers theta function Θa,b. We construct a higher-dimensional generalization of Zwegers theta functions as integrals of &thetas;km over geodesic simplices for n ≥ 2. If Γ is a discrete group of isometries of V that preserve the lattice L and act trivially on the cosets L*/L, then the fundamental region Γ\D is an arithmetic locally symmetric space. We prove that the integral of &thetas; km over Γ\D converges and compute it in some cases. In particular, we extend the results of Kudla to the cases p = 1, and q odd.

Keywords: Modular form
Symmetric space
Theta function
Advisor: Kudla, Stephen
Examining Curricular Integration Strategies To Optimize Learning Of The Anatomical Sciences

Background: Integration of basic and clinical science knowledge is essential to clinical practice. Although the importance of these two knowledge domains is well-recognized, successfully supporting the development of learnersâ integrated basic and clinical science knowledge, remains an educational challenge. In this dissertation, I examine curricular integration strategies to optimize learning of the anatomical sciences. Objectives: The studies were designed to achieve the following research aims: 1) to objectively identify clinically relevant content for an integrated musculoskeletal anatomy curriculum; 2) to examine the value of integrated anatomy and clinical science instruction compared to clinical science instruction alone on novicesâ diagnostic accuracy and diagnostic reasoning process; 3) to compare the effect of integrating and segregating anatomy and clinical science instruction along with a learning strategy (self-explanation) on novicesâ diagnostic accuracy. Methods: A modified Delphi was used to objectively select clinically relevant content for an integrated musculoskeletal anatomy curriculum. Two experimental studies were created to compare different instructional strategies to optimize learning of the curricular content. In both of these studies, novice learners were taught the clinical features of musculoskeletal pathologies using different learning approaches. Diagnostic performance was measured immediately after instruction and one-week later. Results: The results show that the Delphi method is an effective strategy to select clinically relevant content for integrated anatomy curricula. The findings also demonstrate that novices who were explicitly taught the clinical features of musculoskeletal diseases using causal basic science descriptions had superior diagnostic accuracy and a better understanding of the relative importance of key clinical features for disease categories. Conclusions: This research demonstrates how integration strategies can be applied at multiple levels of the curriculum. Further, this work shows the value of cognitive integration of anatomy and clinical science and it emphasizes the importance of purposefully linking the anatomical and clinical sciences in day-to-day teaching.

Keywords: basic sciences
clinical reasoning
diagnostic reasoning
integration
medical education
teaching strategies
Advisor: Agur, Anne M.R
Woods, Nikki N
Teacher Reciprocal Learning in International Professional Communities Between Ontario and Shanghai Schools

This study investigates teachers’ cross-cultural professional learning in an emerging Canada-China school network that involved Ontario and Shanghai educators. Drawing on the literature of teacher learning in professional learning communities (PLCs), particularly networked PLCs, this study sheds light on teacher learning and its supportive conditions in the international setting. The educators who participated were interviewed while observational data about their cross-cultural collaboration were collected over a period of two years. This exploratory comparative study concluded with a tentative model for teacher reciprocal learning in internationally networked PLCs (INPLCs) in light of empirical data in order to stimulate future research and practice. The data shows that thematic activities and videoconferences helped teachers collaborate and learn in these INPLCs. The teachers mutually benefited from these interactions although they also encountered some setbacks associated with the international exchange. The data validates that these teachers’ learning experiences impacted their knowledge, practice, professional identity, and motivation to participate. This study also identifies six within-school and six within-network supportive organizational conditions. Based on these findings and the knowledge from the literature, suggestions are made to further develop the nascent Canada-China school network in a hope of bringing about more teacher learning. This study joins the research on international school partnerships or networks that are possibly conducive to student growth, teacher learning, and school development. Overall, this exploration reveals that given right organizational conditions it is possible to create an effective reciprocal learning space involving school educators from two places that differ educationally, culturally, and historically. Meanwhile, this study shows the potential of one comparative education that features participants’ direct interaction. With the evidence of in-service teachers’ cross-cultural professional learning in the context of Ontario and Shanghai education, it demonstrates a way of research that investigates and compares participants’ interactions and reciprocal learning in the international setting.

Keywords: Internationally networked PLC(INPLC)
Networked PLC
Professional learning community(PLC)
Reciprocal learning
School education
Teacher learning
Advisor: Anderson, Stephen
Mechanism of Crushing of Rocks under Dynamic Loading

In the mining and quarrying operation, rock crushing process consumes a large amount of energy. Therefore, it is necessary to generate a better understanding of the fragmentation process. Although a number of crushing tests have been reported, most of these tests are based on single particle crushing tests. Considering rock fragments in a crusher interacts with the surrounding fragments, a multi-particle crushing test is essential to simulate crushing process. Based on this motivation, a set of laboratory crushing tests was developed, which consists of single particle and multi-particle crushing tests. In the single particle crushing test, the crushing strength of two type of rocks (Laurentian granite and Kuru granite) were investigated under different loading rates. It is found that the dynamic crushing strength increases with loading rate and is much higher than the static one. In this work, we firstly designed a multi-particle crushing apparatus based on the principle of Hopkinson bar system. In the multi-particle crushing test, the relation between energy consumption and particle size reduction was examined. The multi-particle crushing test involved five types of rocks (Laurentian granite, Barre granite, Kuru granite, Norite, and Flamboro limestone), three impact velocities (2.2, 3.8, and 9.5 m/s), and three feed sizes (A: 9.5~12.7 mm, B: 6.4~9.5 mm, and C: 12.7~15.9 mm). Based on the results of these tests, a new crushability index CRIut was developed, which represents the influence of rock type, impact velocity and the feed size in the crushing process. Thereafter, an empirical model was established based on a dimensionless analysis for better understanding the crushing mechanism of rocks. In this study, a better under a better understanding of the fragmentation behaviour of rocks in crushers and its perceptibility have been achieved.

Keywords: Crushability index
Crushing process
Drilling rate index
Dynamic loading
Multi-particle crushing
Single-particle crushing
Advisor: Mohanty, Bibhu
Xia, Kaiwen
Sources of Self-efficacy, Self-efficacy for Self-regulated Learning, and Student Engagement in Adolescents with ADHD

In the study of motivation and achievement, self-efficacy for self-regulated learning (SESRL) beliefs have been identified as a driving force behind student engagement in learning. Self-efficacy perceptions are thought to be shaped by four key sources of information: mastery experiences, vicarious learning, verbal encouragement, and emotional states. Although adolescents with ADHD exhibit deficits in motivation and self-regulation, few researchers have examined SESRL beliefs in this population, including the sources of self-efficacy and their potential influence on student engagement. Therefore, the objectives of this dissertation were to: (1) examine group (ADHD versus comparison) and gender differences in the sources of self-efficacy, SESRL, and student engagement, and (2) investigate the relations between these variables and symptoms of inattention. Adolescents completed measures of the sources of self-efficacy, SESRL, and engagement, while parents rated their childrenâ s inattention symptoms. To address objective one, participants were 98 adolescents (age 14 to 16), with 47 (30 males, 17 females) classified as having ADHD and 51 (19 males, 32 females) forming a typically functioning comparison group. To address objective two, the ADHD and comparison groups were combined to form a larger sample of 105 adolescents (53 males, 52 females). Results revealed that, relative to their non-ADHD peers, adolescents with ADHD rated themselves as having fewer mastery experiences, less positive encouragement from others, lower SESRL beliefs, and lower levels of engagement. Gender differences also emerged in the sources of self-efficacy, with male adolescents rating themselves lower than females in mastery experiences, vicarious learning, and verbal encouragement. Path analysis in the full sample showed that the sources of self-efficacy and SESRL mediated the relationship between inattention and student engagement. These results contribute to our understanding of motivation in adolescents with ADHD and shed light on how they perceive themselves and their school experiences. Clinical and educational implications involve designing interventions that not only focus on building knowledge and skills, but also on supporting adolescents in developing the confidence to succeed.

Keywords: Achievement
ADHD
Engagement
Self-Efficacy
Self-Regulated Learning
Sources of Self-Efficacy
Advisor: Martinussen, Rhonda