VictorJuiz/thesis huggingface dataset:
A Comprehensive Piezoelectric Bending-Beam Model Inspired by Microaerial Vehicle Applications
Keywords: Actuators
Dragonfly
Flapping Wing
Microaerial Vehicles
Piezoelectric
Sensors

Microaerial vehicles are an up-and-coming area of robotics which is fuelled by modern understanding of the unsteady aerodynamics of insect flight and the development of new actuation technologies. In the past two decades computer simulations have aided in uncovering the lift mechanisms which flying insects use to stay aloft. Using these details, roboticists had begun using lightweight structures and high power density actuators to mimic the physical parameters and flapping kinematics of flying insects with the intent to recreate the dynamics of insect flight. One of the most important aspects of flapping-wing microaerial vehicles is the actuation method. Piezoelectric bending-beam actuators have been scaled up from MEMS technology for use in microaerial vehicle applications owing to their high power density and performance at low mass. The initial development toward the UTIAS Robotic Dragonfly, a microaerial vehicle platform using a piezoelectric-based actuator, is outlined. The components are fabricated from lightweight materials such as a carbon fibre frame, polymide film joints, and polyester film wings while the actuator is a piezoelectric bending-beam which was designed using existing mathematical models. The design and fabrication of the wings, actuator, transmission, and power supply are detailed. The prototypes are measured for lift generation using custom lift sensors which had undergone static and dynamic calibration for low-force, high-bandwidth measurement. Although the resulting lift curves qualitatively correspond with the literature, it was determined that more power was needed for lift-off to be achieved and existing piezoelectric models do not fully account for maximizing the force-deflection relationship. An extension to the existing Ballas model of piezoelectric bending-beam devices is derived. This modified Ballas model incorporates devices beyond constant width. Actuator performance limitations highlighted the need for a more comprehensive piezoelectric bending-beam model. The final contribution is a derivation of a new bending-beam model to permit multiple layers, any continuous width profile, and independent layer excitation. An energy-based approach using the extended Hamilton's principle was used to incorporate the generalities desired in the new piezoelectric bending-beam model. Examples of the new model are compared to both simulation and experiment for verification as well as to showcase its versatility.
Attention and Inhibitory Control in Children with Traumatic Brain Injury: Outcomes and Prediction Using Biomarkers
Keywords: attention
executive function
pediatric
serum biomarkers
traumatic brain injury

Children with traumatic brain injury (TBI) have a range of cognitive problems, notably in the domain of executive functioning and attention. Previous studies have attempted to relate performance on measures of executive function and attention in groups of children with TBI to pre-injury variables and measures of TBI severity, to predict outcome, but clear relations have not emerged. This is likely due to variability in both patient and injury characteristics. Prior studies also have not found consistent results as to why these cognitive difficulties are so frequently seen as sequelae to TBI in children. This thesis evaluated a variety of patient variables, along with serum biomarkers (proposed objective measures of brain injury), as predictors of long-term (one to six years) attention and executive function outcome in children following TBI. A secondary aim of this thesis was to investigate performance monitoring through the use of the stop signal task (SST) in children following TBI compared to age-matched controls. Significant relations were found between serum biomarkers (such as neuron specific enolase [NSE] and soluble neuron cell adhesion molecule [sNCAM]), pre-injury functioning, and persistent attention and executive function difficulties at long-term follow-up time points. Other standard clinical measures (Glasgow Coma Scale, age) were not reliable predictors. During performance monitoring, children with TBI did not show the expected slowing in reaction time following an error on the SST that was observed in an age-matched healthy control group, but the group differences were not significant. When validated in future research studies, the findings of the predictive value of certain serum biomarkers and pre-injury measures could contribute to acute clinical and long-term rehabilitation decisions, with the expectation of improving the quality of life in survivors of paediatric TBI.
Compact Object Binaries With Spinning Neutron Stars In Numerical Relativity
Keywords: Black Holes
Gravitation
Gravitational Waves
Neutron Stars
Numerical Relativity
Simulation

The inspiral and merger of binary neutron stars (BNS) is one of the most promising potential sources of gravitational waves for ground-based detectors like Advanced LIGO. BNS mergers are also likely a source of counterpart electromagnetic radiation. It is important to perform simulations of BNS to better understand and model their gravitational wave emission as well as their electromagnetic emission. The parameter space of BNS binaries is quite large, and one aspect that has not been well studied in neutron star spin. In this thesis, we focus on investigating spinning neutron stars in compact object binaries. Using the SpEC code, developed by the SXS collaboration, we begin by presenting a new code to create initial data for binary neutron stars with arbitrary spins. We introduce a novel method of measuring neutron star spin, and show that it is accurate and robust. We evolve several spinning binary configurations and show that their properties agree remarkably well with Post-Newtonian predictions. We also show that we are able to control the eccentricity of the binaries to ~0.1%. Thereafter, we proceed to extend our code to black hole--neutron star (BHNS) binaries. We create many data sets across the BHNS parameter space, varying neutron star spin magnitude, spin direction, compactness, and black hole mass, spin and spin direction. We are able to create initial data sets with neutron star spins near the mass-shedding limit, and nearly extremal black hole spins. Finally, we investigate spurious gravitational radiation in binary black hole systems. We study its parameter space dependence, by introducing three diagnostics, investigating them as a function of black hole spin and black hole separation, and comparing two different methods of constructing initial data.
Exploring the Role of Inflammatory Cytokines in the Pathophysiology, Cognitive Dysfunction and Treatment of Bipolar Disorder: Integrative Evidence Provided by a Proof-of-Concept Study with Adjunctive Minocycline
Keywords: bipolar disorder
cognition
Cytokines
Inflammation
minocycline
mood disorders

Background: Bipolar disorder (BD) is associated with increased levels of inflammatory cytokines, which may contribute to cognitive dysfunction. Anti-inflammatory intervention with minocycline is hypothesized to exert antidepressant and pro-cognitive effects in BD. The aims of the investigations were: 1) to identify inflammatory cytokine abnormalities in BD; 2) to identify inflammatory cytokines associated with cognitive dysfunction in BD; 3) to evaluate the efficacy of adjunctive minocycline for symptoms of bipolar depression and cognitive dysfunction. Method: The first two study aims were evaluated with cross-sectional exploratory methods, comparing 29 depressed (HAMD-17 ≥ 20) and 46 euthymic (4 week verification) adults with DSM-IV-TR-defined BD as well as of 31 healthy controls (HCs). Plasma cytokine levels were measured with a 30 V-PLEX immunoassay. Evaluated cognitive domains were verbal memory, executive function and psychomotor speed. The efficacy of adjunctive minocycline (100 mg b.i.d.) was evaluated in an overlapping sample of depressed individuals (intent-to-treat: n=27) using an 8-week, open-label study. The primary efficacy measure was the MADRS, while, cognitive composites and plasma cytokines were secondary outcome measures. Results: Results from multinomial logistic regression analyses indicate that IL-6 levels were increased in depressed and euthymic individuals with BD when compared to HCs, while, levels of CCL3, IL-15, and IL-17A were reduced below levels of HCs in euthymic individuals (Pseudo R2=.648, p
Aqueous Phase Diffusion Related Isotope Fractionation in Groundwater Systems
Keywords: Contamination
Diffusion
Dispersion
Groundwater
Isotope fractionation
Modelling

Aqueous phase diffusion-related isotope fractionation (DRIF) for stable carbon isotopes was investigated for common groundwater contaminants through modelling to determine under what conditions DRIF effects would be observable. This study proposes a critical dispersive enrichment factor of (‒0.32‰), above which the isotope fractionation due to different dispersion coefficients of light and heavy isotopologues may be significant. This study also reveals that the key factors constraining the observation of DRIF include the ratio of macrodispersion coefficient to effective diffusion coefficient (λv/Deff), the ratio of initial contaminant concentration to the method detection limit for isotope analysis (C0/MDL), the diffusive fractionation factor, the presence of low-permeability zones, local scale compound specific transverse mechanical dispersion, soil heterogeneity, sampling method and occurrence of biodegradation. This study provides important constraints on the conditions that would merit close investigation of carbon isotope DRIF effects. These conditions include compounds with smaller molar masses (e.g., vinyl chloride or benzene) which can lead to larger diffusive fractionation factors (father from unity) and sites with high C0/MDL ratios (i.e. > 50), low λv/Deff ratios (i.e.
Surface-atmosphere and Gas-particle Partitioning of Ammonia: Measurements, Modelling, and Trend Analysis
Keywords: Aerosol acidity
Ammonia
Instrument optimisation
Trend analysis
Vertical profiles

Atmospheric ammonia is of interest because of its impacts on ecosystem and human health, as well as climate. Processes of surface-atmosphere and gas-particle exchange were investigated through measurements, modelling, and long-term trend analysis. A Quantum Cascade-Tuneable Infrared Laser Differential Absorption Spectrometer (QC-TILDAS) was characterised for the purposes of making direct eddy covariance (EC) flux measurements of bi-directional surface-atmosphere ammonia exchange. While this instrument has great potential, improvements are needed in both sensitivity and time response of the instrument if it is to be used to make EC flux measurements. This instrument was further used to measure vertical profiles of ammonia mixing ratios, investigating the influence of the surface on column distribution, and the variation in diurnal trends with altitude. Ammonia mixing ratios were found to increase towards the surface, with greater variability during the daytime than at night. Diurnal trends in ammonia were found to change with altitude: all heights showed a daytime maximum, and the lowest measurement height showed an additional nighttime maximum. Atmospheric ammonia is closely tied to aerosol particle composition, especially in terms of particle acidity, which can alter the health and climate impacts of such particles. A 21 year dataset of particle composition was used to determine spatial and temporal trends in particle acidity. It was found that particle acidity decreased significantly over this time period, concurrent with decreases in emissions of SO2 and NOx, with implications for air quality and atmospheric chemistry. Additionally, there is a need for greater consistency in metrics used to describe particle acidity. Finally, thermodynamic and kinetic models were used to explore the potential impacts of this particle acidity on gas-particle, and consequently surface-atmosphere exchange of ammonia, demonstrating the connection between these two equilibrium processes.
Towards a Storage Stack for the Data Center
Keywords: Data Center
Performance
Reliability
Software-Defined Storage
Storage

The storage stack in a data center consists of all the hardware and software layers involved in processing and persisting data to durable storage. The shift of the world's computation to data centers is placing significant strain on the storage stack, leading to a stack that is unreliable and non-performant. This is caused in large part by a lack of understanding of the failure and performance characteristics of critical hardware components, and a lack of programmability and control over the numerous software layers in the stack. The broad goal of this thesis is to improve the storage stack by leveraging insights gained from empirical studies of real-world production systems, and by proposing a new paradigm for implementing and enhancing distributed storage functionality that enables the vertical specialization of the storage stack to a wide variety of customer and data center provider needs. The first part of this thesis studies the reliability of main memory in large-scale production systems. Our findings show that conventional wisdom about memory reliability is incorrect, and that physical hardware is in fact the main culprit for most errors in main memory in the field. As a result, existing memory error protection mechanisms are inadequate. We then use the insights gained from the empirical study to propose and evaluate a suitable error protection mechanism for future data centers. The second part of this thesis offers an empirical study of the effects of temperature on the performance and power consumption of the storage stack. Since cooling constitutes a large fraction of the total cost of ownership in a data center, increasing temperatures in a data center without sacrificing performance can have a huge impact on the power consumption and carbon footprint of data centers. The final part of this thesis proposes a new paradigm for implementing and enhancing distributed storage functionality by creating programmable APIs that allow dynamic configuration and control of the software stages along the storage stack, and designing and implementing an IO routing primitive for the storage stack.
Incurable Invisible: Living with Advanced Disease in a Canadian Cancer Hospital
Keywords: cancer
culture
liminality
medical anthropology
oncology
palliative care

This thesis follows the lives of people who are diagnosed with a cancer that is unlikely to be cured. This means that even if patients receive one or multiple rounds of the standard treatments of chemotherapy, surgery and radiation, there is a high probability that they will still die from their disease. Incurable illness presents a particular problem due to a combination of cultural meanings and values, both within biomedicine and within society. Drawing on 17 months of ethnographic fieldwork conducted in one Canadian cancer hospital, working with patients with lung and gynaecological cancers, the dissertation answers the question: What is life like for patients with advanced cancer as they live with their disease, post-diagnosis? Although its focus is primarily on the patients, it also includes the experiences of doctors and nurses at the hospital, and patients’ family and friends. I explore some of the challenges and tensions produced from living with a diagnosis of advanced cancer. For example, patients are advised to ‘live in the moment,’ but this is a very challenging directive to follow as it is interlaced with the connotation that they are being entreated to do so because their futures are uncertain. Similarly, patients have to muster enough hope to be able to endure the emotionally and physically demanding treatments, but not so much hope that they believe that the treatments will actually cure them of their disease. These entreaties require them to straddle both the worlds of oncology and survivorship and the worlds of death, dying and palliative care, which my findings indicate is extremely difficult to withstand on a day-to-day basis. I argue that advanced cancer is a kind of ‘liminal’ space, an ambiguous territory that exists between the hope for a cure and the imminence of death. Patients’ ambiguous position is made even more challenging since contemporary cancer culture in North America tends to highlight only cancer survivors or people who have ‘lost their battles’ from cancer, rendering the struggles and experiences of patients who are living with advanced cancer but not currently dying from it, both culturally silent and invisible.
Two Results on Asymptotic Behaviour of Random Walks in Random Environment
Keywords: Probability
Random Environment
Random Walk
Statistical Physics

In the first chapter of this thesis, we introduce a model of directed polymer in 1 + 1 dimensions in a product-type random environment ω(t, x) = b(t)F(x), where the fields F and b are i.i.d., with F(x) continuous, symmetric and bounded, and b(t) = ±1 with probabilty 1/2. Thus ω can be viewed as the field F oscillating in time. We consider directed last-passage percolation through this random field; namely, we investigate the behavior of the length n polymer path which maximizes the sum of the environment variables it moves through. We prove a law of large numbers for the maximal action of the path from the origin to a fixed endpoint (n,⌊αn⌋), and investigate the limiting shape function a(α). We prove that this shape function is non-linear on [0, 1], and has a corner at α = 0, thus indicating that this model does not satisfy the KPZ scaling relation, despite ω(t, x) having delta-correlations in t and x. We conjecture that this shape function has a linear piece near α = 0. With probability tending to 1, the maximizing path with free endpoint will localize on an edge with F values far from each other. Assuming a conjecture on the arrival time to this localization site, we prove that the path endpoint and the centered action of the path, both rescaled by n−2/3, converge jointly to a universal law, given by the maximizer and value of a functional on a Poisson point process. In the second chapter, we consider a class of multidimensional random walks in random environment, where the environment is of the type p0 + γξ, with p0 a deterministic, homogeneous environment with underlying drift, ξ an i.i.d. random perturbation, and γ a real number characterizing the strength of the randomness. Such environments were considered by Sabot in [31], who finds a third-order expansion in γ for the non-null velocity (which is guaranteed to exist by Sznitman and Zerner’s LLN [36]). We prove that this velocity is an analytic function of the perturbation, by applying perturbation theory techniques to the Markov operator for a certain chain in the space of perturbations.
Synthesis and Surface Reactions of Hydride Terminated Silicon Nanocrystals with Strong Quantum Size Effect
Keywords: CO2 reduction
hydride
hydrosilylation
photoluminescence
quantum size effect
silicon nanocrystals

Among the variety of semiconductor quantum dots targeted for applications in optoelectronics, biological imaging and chemical sensing, silicon nanocrystals (ncSi) are drawing increasing attention because of their earth-abundance, low cost, and purported lack of toxicity. To synthesize freestanding ncSi, we employed several methods that could all yield hydride-terminated ncSi and which allow further surface functionalization and chemical reactions. Among these methods, a batch synthesis based upon the solid-state disproportionation of SiO powder has not previously drawn much attention in chemistry. We describe some remarkable effects observed in the diffraction, microscopy and spectroscopy of SiO powder upon thermal processing in the temperature range 850-1100 ℃, pinpointing that the most significant disproportionation transformations happened in the range between 900 and 950 ℃. With this know-how a high yield synthesis was developed that produced polydispersions of decyl-capped, hexane-soluble ncSi predominantly with NIR photoluminescence. The hydrosilylation reaction was carried out via both the conventional heating and the unconventional microwave heating methods, and the kinetics were studied for the first time. Using size-selective precipitation, these polydispersions were separated into monodisperse fractions, which allowed their photoluminescence absolute quantum yield to be studied as a function of ncSi size. This investigation yielded volcano-shaped plots confirming the most efficient photoluminescence wavelength for ncSi to be located at 820-830 nm, which corresponded to a size of 3.5-4.0 nm. Finally, we describe the unprecedented observation that ncSi:H can function as a single component heterogeneous reducing agent for converting gaseous CO2 selectively to CO, at an impressive rate of hundreds of micromol/h∙g. The large surface area, broadband light harvesting and reducing power of SiH surface sites together play key roles in the conversion. This thesis work provides opportunities for applications of size-selected near infrared emitting ncSi in biomedical imaging, photothermal therapy, and CO2 reduction for the production of chemicals and fuels.
Exploring the Memory Advantage for Vocal Melodies
Keywords: Melody
Memory
Music
Timbre
Voice

The voice is a biologically significant and spectrally rich signal that plays a critical role in communication and social engagement throughout life. Nevertheless, music cognition and perception research does not typically use vocal music as stimuli, opting instead for timbres that are easier to manipulate and control (e.g., digital instruments). The evolutionary and ontogenetic significance of the voice are among the reasons to expect distinctive and favored processing of vocal music. The single previous comparison of memory for vocal and instrumental melodies revealed superior recognition of vocal melodies and no differences among various instrumental renditions (Weiss, Trehub, Schellenberg, 2012). This dissertation explores various facets of the â vocal memory advantageâ by (1) testing additional populations of listeners (children, Brazilian musicians and nonmusicians), (2) using physiological (pupil dilation) as well as behavioral responses, (3) examining the implications of divided attention (a concurrent task), and (4) confirming the generality of the findings across male and female vocalists. Children between 7 and 11 years of age remembered vocal melodies better than instrumental renditions, but younger children had poorer overall memory and were biased to judge vocal melodies as familiar. Brazilian musicians and nonmusicians displayed a similar memory advantage for vocal melodies, and expert pianists remembered piano melodies no better than other instrumental melodies. Listeners exhibited enhanced arousal for vocal melodies relative to piano melodies and for melodies heard previously than for novel melodies, as reflected in greater pupil dilation. Conditions of divided attention revealed greater attention allocation to vocal melodies than to piano melodies, as reflected in modestly greater impairment on a concurrent visual task during vocal melody presentation. Finally, the memory advantage was comparable for the original female vocalist used in Weiss et al. (2012) and two new vocalistsâ one female, and one male. Collectively, the research in this dissertation provides definitive evidence that musical timbres are unequal in their consequences for music perception and cognition. Specifically, vocal and instrumental melodies have differential effects on arousal, attention, and memory.