VictorJuiz/thesis huggingface dataset:
Producing Small Droplets of Aqueous Solutions and Molten Metals using a Pneumatic Droplet Generator
Keywords: drop-on-demand

A pneumatic droplet generator is described, which consists of a T-junction with a nozzle fit into one opening, the second opening is connected to a gas cylinder through a solenoid valve and the third connected to a length of steel tubing. The droplet generator is filled with liquid. Opening the valve for a preset time creates a pulse of alternating negative and positive pressure in the gas above the surface of the liquid. A jet of liquid issues far enough out of the nozzle that its tip becomes unstable, detaches and forms a droplet. Experiments were conducted using water/glycerin mixtures and molten metals including tin, zinc and zinc alloy. Droplet formation was photographed and the pressure variation inside the droplet generator recorded. The effect of various experimental parameters such as nozzle size, pressure pulse width, secondary gas flow pressure, liquid viscosity and temperature on droplet formation were investigated. An analytic model of incompressible liquid motion in the nozzle is used to explain the behavior of water/glycerin solutions inside the nozzle and droplet formation. The model demonstrates that the motion of the surface is out of phase with the exciting pressure oscillation. Experiments showed the oscillation of the liquid surface prior to droplet ejection and the time lag between the pressure oscillation and droplet ejection. The model predicts that maximum liquid velocity is attained at an intermediate value of viscosity, and experiments confirmed that the largest liquid motion was achieved with this intermediate value, which eventually leads to droplet formation. Similarly, with molten metals, a simple analytical method was used to estimate the diameter of droplets. The size of tin droplets measured from experiments was in good agreement with that obtained from the model.
Becoming a Family Physician – Exploring the Experiences of Residents During the First Six Months of PostgraduateTraining
Keywords: transitions
medical education
postgraduate

Becoming a Family Physician – Exploring the Experiences of Residents During the First Six Months of Postgraduate Training describes the early training experience of residents from their perspective as they begin a postgraduate program in Family Medicine. A case study approach using focus groups and individual interviews was used to gain insight into the resident-participant’s experiences of the first six months of training. Resident-participants were asked to describe their concerns, changes that occurred and the influences they attributed to those changes as a way to explore their early training experiences from their perspective. This study found resident-trainees do not begin a Family Medicine postgraduate training program knowing what it means to be a Family Physician, but must learn what it means to fulfill this role. From the participants’ perspective, this process involves adjusting to significant shifts in responsibility in the areas of Knowledge, Practice Management and Relationships that occur when they make the transition from being medical students in undergraduate training to doctors responsible for the outcome of care during postgraduate training. As the participants began postgraduate training they were eager to accept the responsibility of being the doctor, but were uncertain they had the necessary medical experience and expertise for someone calling themselves the doctor. The experience of practice, which included developing relationships with different patients over time (continuity of care) was particularly influential in helping the participants gain confidence in fulfilling the role of doctor and learning that the role of Family Physician is complex, multifaceted and not limited to their initial concept of doctoring. As the participants adjusted to their new responsibilities, they gained confidence in their new role as doctor, which subsequently led to a more comprehensive understanding of what it meant to be a Family Physician. This study was able to contribute to what little is know about the transition into a postgraduate Family Medicine program by illuminating from the resident-participant’s perspective how the transition is experienced. In doing so, medical educators have a better understanding of the early training experience of resident-trainees and how these experiences contribute to consolidating their new professional identity.
Young Women's Provisioning: A Study of the Social Organization of Youth Employment
Keywords: young women
employment
provisioning
social policy

This study uses institutional ethnography (IE) to address the question of how young women, considered to be “at risk” youth, make decisions about their working lives. Based on interviews with young women and program workers in housing, employment, young mothers’ and girls’ programs, field observations, and document analysis at Gen-Y (pseudonym for a women’s community-based social services agency), young women’s provisioning experiences are used to critique current program and policy models that feature notions of choice and risk. Provisioning is a concept that captures a wide range of work and work-related activities that young women perform for themselves and people they feel responsible for. IE is applied to understand how institutional processes and practices give rise to the conditions under which young women participants at Gen-Y make career and life decisions.
Mechanomyography as an Access Pathway for Binary and Multifunction Control
Keywords: access technology
muscles
mechanomyography
rehabilitation
biomedical engineering

Individuals with severe physical disabilities and minimal motor behaviour may benefit from access technologies that harness the volitional activity of muscles. In this thesis, we investigate the use of muscle activity, indicated by the mechanomyogram (MMG), as a binary and multifunction control signal for access devices. A challenge in the design of a binary MMG switch is to reliably recognize the timing of voluntary muscle contractions, and to subsequently translate the MMG signal into a switch-activation signal. A continuous wavelet transform (CWT) algorithm based on a simplified MMG generation model of recurring impulsive morphological patterns was proposed for automatic detection of muscle activity from MMG signals. CWT coefficients of the MMG signal were compared to scale-specific thresholds derived from the baseline signal to estimate the timings of muscle activity. The automatic detection algorithm was implemented as a binary switch controlled by a single muscle site at the forehead, shoulders or forearm. The binary control algorithm was verified on able-bodied participants, and the switch was tested on individuals with neuromuscular and neurological disabilities. The switch showed very high sensitivity and specificity when the muscle and its control were minimally affected by spasticity, involuntary movement, or involuntary muscle activity. We further investigate the potential of improving the functionality of the MMG-controlled switching interface. We demonstrate the practical use of the vibratory artefact measured at the forehead during vocalization to control a second switch. The proposed integrated MMG-vocalization access solution may augment access alternatives for individuals with physical disabilities using a single access site. Further, we show that multi-site MMG signals exhibit distinctive patterns of forearm muscle activity, and 7+/-1 hand movements can be identified with an accuracy of 90+/-4%. This suggests that MMG may have applications in multi-function body-machine interfaces when multiple muscle sites are available. However, MMG signal features vary with sensor location. We show that sensor displacements significantly diminish classification accuracy, emphasizing the importance of consistent sensor placement between MMG classifier training and deployment for accurate control of switching interfaces. Collectively, the findings and developments of this thesis lay the foundation for future research on wearable, MMG-driven access technologies.
Molecular Modeling of Immobilized Single and Double Stranded Oligonucleotides in Mixture with Oligomers
Keywords: Molecular Modelling
Biosensors
AMBER
DNA
Silica surfaces
computational Chemistry

Interactions between single and double stranded oligonucleotides with SiO2 surfaces and the interactions between oligonucleotides and immobilized oligomers have been studied computationally. The oligonucleotide is the 18-base-pair sequence for the survival motor neuron gene SMN1. The oligomer consisted of a 50 unit 2-hydroxyethyl methacrylate (PHEMA) molecule. A linker used to tether the oligonucleotide was either a 10 Å or a 30 Å long succinimdyl 4-[N-maleimidomethyl]cyclohexane-1-caroxylate (sulfo-SMCC-Cn). The surface consisted of a SiO2 crystal that was 50 Å long and 50 Å wide, one unit thick and covered with modified-(3-aminopropyl)trimethoxysilane (m-APTMS) molecules. It was determined that explicit water, sodium counterions and excess salt were necessary to produce computationally stable oligonucleotide structures on surfaces. Artificial partial charges were introduced to the surface, and linkers, oligomers and oligonucleotides were immobilized and studied. The linkers collapsed onto a positive but not onto a negative surface. Oligomers moved closer to the SiO2 surface regardless of the surface charge. Immobilized oligonucleotides tilted significantly from an initial upright position but did not collapse completely onto the surfaces. The interactions between immobilized oligonucleotides and oligomers were examined. The number of oligomers surrounding the oligonucleotide was varied between two and four. Single stranded oligonucleotides were prevented from interacting with the surface as they were inhibited by the presence of oligomers. Double stranded oligonucleotides collapsed onto the surface when only two oligomers were present but remained upright when four oligomers were present. This was due to the four oligomers interacting with one another and effectively shielding the surface. The oligomers interacted with the bases in the single stranded oligonucleotides, making them energetically accessible. Presence of a high density of oligomers prevented the dsDNA from collapsing onto the surface. These results suggest design criteria for preparation of mixed oligonucleotide and oligomer films for use in biosensors.
On the Reflexive Prioritisation of Locations in Visual Space
Keywords: attention
working memory
attention capture
visual working memory
attentional control settings
reflexive visuospatial attention

The efficiency of human visual information processing is supported by numerous attentional resources. These resources ensure that behaviourally relevant information within visual scenes is selected for detailed processing, while behaviourally irrelevant information is ignored. One of these attentional resources—reflexive visuospatial attention—operates by prioritising locations in visual space in response to the appearance of salient stimuli. The purpose of the present dissertation was to examine how this type of attention contributes to the efficiency of visual processing by asking: How is processing altered for information presented at the location of attention? To develop some initial evidence of the stage of processing affected by reflexive visuospatial attention, Chapters 1 to 6 assessed whether this attentional resource is related to four other stimulus-driven effects that are each associated with a specific stage of visual processing: identity processing, object filtering, visual working memory (VWM), and response generation. Based on the observation that only the stimulus-driven effects on VWM are related to reflexive visuospatial attention (i.e., only those effects were contingent on attentional control settings), a VWM model of reflexive visuospatial attention was proposed in Chapter 7, and tested in Chapters 8 to 11. According to this model, reflexive visuospatial attention alters visual processing by triggering VWM to update. Thus, the effect of reflexive visuospatial attention is to speed the encoding of attended information into VWM. As a result, this information is more likely than unattended information to bias our behaviour, in particular those behaviours that depend on VWM. Further, by biasing VWM, reflexive visuospatial attention can interact with other attentional resources that have also been associated with VWM. In this way, these attentional resources can coordinate in optimising the process of selection, thus, contributing to the efficiency of the human visual system.
CYP2A6 and CYP2B6: Sources of Variation and their Role in Nicotine Metabolism
Keywords: Nicotine
CYP2A6
Pharmacogenetics
CYP2B6

Nicotine is the primary substance in tobacco causing addiction. In humans the majority (70-80%) of nicotine is inactivated to cotinine in a reaction predominantly catalyzed by CYP2A6 (80-90%), with a minor possible role for CYP2B6. Substantial interindividual variability is observed in the rate of nicotine’s inactivation to cotinine and this variation contributes to differences in smoking behaviors (e.g. cigarette consumption). Twin studies suggest an important genetic contribution to the variability in nicotine metabolism. However in 2004, genetic variation in CYP2A6 and CYP2B6 accounted for only a small portion of the variability suggesting gaps in our knowledge. Our objective was to identify additional genetic and non-genetic sources of variability in CYP2A6 expression/activity, CYP2B6 expression, and nicotine to cotinine metabolism in vivo and/or in vitro. Participants included individuals from different world populations phenotyped for CYP2A6 activity either following oral nicotine administration or using metabolite ratios derived from baseline smoking. Genotyping and sequencing were utilized to identify and characterize multiple new CYP2A6 alleles. In total 17 novel CYP2A6 alleles were identified, many of which were found predominantly among individuals of black African descent and exhibited lower CYP2A6 activity. In addition, human livers were assessed for CYP2A6 and CYP2B6 expression and nicotine to cotinine metabolism. The mechanisms underlying the lower CYP2A6 activity associated with some of the variant CYP2A6 alleles included either a reduction in hepatic CYP2A6 protein expression, an alteration of CYP2A6’s structural property, or a combination of both. DNA methylation was not associated with altered hepatic CYP2A6 expression/activity. Livers from female donors were associated with higher CYP2A6 and CYP2B6 protein expression compared to male livers, while age did not influence the expression of either CYP. Finally, CYP2B6 and its prevalent altered function genetic variant (CYP2B6*6) did not influence nicotine to cotinine metabolism. Identification of factors that contribute to the variability in CYP2A6 and nicotine metabolism is important to improve future association studies between CYP2A6 genotype, nicotine metabolism, and smoking behaviors. In addition, this information could provide the potential to personalize therapy in order to improve the clinical efficacy of nicotine, particularly as a smoking cessation aid.
Ground Penetrating Radar Imaging of Ancient Clastic Deposits: A Tool for Three-dimensional Outcrop Studies
Keywords: Ground Penetrating Radar
GPR

The growing need for better definition of flow units and depositional heterogeneities in petroleum reservoirs and aquifers has stimulated a renewed interest in outcrop studies as reservoir analogues in the last two decades. Despite this surge in interest, outcrop studies remain largely two-dimensional; a major limitation to direct application of outcrop knowledge to the three dimensional heterogeneous world of subsurface reservoirs. Behind-outcrop Ground Penetrating Radar (GPR) imaging provides high-resolution geophysical data, which when combined with two dimensional architectural outcrop observation, becomes a powerful interpretation tool. Due to the high resolution, non-destructive and non-invasive nature of the GPR signal, as well as its reflection-amplitude sensitivity to shaly lithologies, three-dimensional outcrop studies combining two dimensional architectural element data and behind-outcrop GPR imaging hold significant promise with the potential to revolutionize outcrop studies the way seismic imaging changed basin analysis. Earlier attempts at GPR imaging on ancient clastic deposits were fraught with difficulties resulting from inappropriate field techniques and subsequent poorly-informed data processing steps. This project documents advances in GPR field methodology, recommends appropriate data collection and processing procedures and validates the value of integrating outcrop-based architectural-element mapping with GPR imaging to obtain three dimensional architectural data from outcrops. Case studies from a variety of clastic deposits: Whirlpool Formation (Niagara Escarpment), Navajo Sandstone (Moab, Utah), Dunvegan Formation (Pink Mountain, British Columbia), Chinle Formation (Southern Utah) and St. Mary River Formation (Alberta) demonstrate the usefulness of this approach for better interpretation of outcrop scale ancient depositional processes and ultimately as a tool for refining existing facies models, as well as a predictive tool for subsurface reservoir modelling. While this approach is quite promising for detailed three-dimensional outcrop studies, it is not an all-purpose panacea; thick overburden, poor antenna-ground coupling in rough terrains typical of outcrops, low penetration and rapid signal attenuation in mudstone and diagenetic clay- rich deposits often limit the prospects of this novel technique.
The Effect of Temperature Primes on Impulsivity
Keywords: Impulsivity
Temperature Primes
Embodied Cognition
Metaphor

Temperature-related words such as “hot” and “cold” are often used to describe impulsive and calculated behaviors, respectively. These metaphoric connotations of thermal concepts raise the question as to whether temperature, psychological states and decision making are related to each other, and if so, how. The current research examines these questions and finds support for a relationship. Across four laboratory experiments and two field studies, I demonstrate that both hot temperature primes (e.g., pictures, words, therapeutic packs) and hot ambient temperature trigger decision outcomes in line with the metaphoric association between hot temperature and impulsivity. I suggest that the theory of embodied cognition provides an explanation for these findings.
Nonparametric Estimation and Inference for the Copula Parameter in Conditional Copulas
Keywords: Dependence
Conditional Copula
Copula Parameter
Covariate Adjustment
Local Likelihood

The primary aim of this thesis is the elucidation of covariate effects on the dependence structure of random variables in bivariate or multivariate models. We develop a unified approach via a conditional copula model in which the copula is parametric and its parameter varies as the covariate. We propose a nonparametric procedure based on local likelihood to estimate the functional relationship between the copula parameter and the covariate, derive the asymptotic properties of the proposed estimator and outline the construction of pointwise confidence intervals. We also contribute a novel conditional copula selection method based on cross-validated prediction errors and a generalized likelihood ratio-type test to determine if the copula parameter varies significantly. We derive the asymptotic null distribution of the formal test. Using subsets of the Matched Multiple Birth and Framingham Heart Study datasets, we demonstrate the performance of these procedures via analyses of gestational age-specific twin birth weights and the impact of change in body mass index on the dependence between two consequent pulse pressures taken from the same subject.
Designing Randomized Clinical Trials for Rare Diseases
Keywords: rare diseases
randomized clinical trials

Objectives: 1) To evaluate the quality of randomized clinical trials (RCTs) in rare diseases using Juvenile Idiopathic Arthritis (JIA) as an example, 2) to evaluate the time to treatment response in patients with rheumatic diseases, 3) to evaluate the power of the Randomized Placebo-Phase Design (RPPD) under various response time distributions, and 4) to examine the use of Value of Information (VOI) methodology in the optimal design of clinical trials for rare disease using hemophilia prophylaxis with factor VIII as an example. Methods. The methods include a systematic review, a secondary analysis of data from an RCT and from a patient registry, a computer simulation study, and an evaluation of hypothetical RCT scenarios with VOI methodology. Results. The quality of RCTs in JIA based on selected quality indicators was poor with some positive changes over time. In the data sets used for the assessment of hazard distributions, the response times followed mostly generalized gamma or lognormal distributions. The impact of time-to-event distribution on the power of RCTs was assessed in computer simulations. Based on the simulation results, the highest sample sizes were observed for response times following the exponential distribution. In most scenarios, the parallel groups RCT design had higher power than the RPPD. The conclusion of the VOI analyses indicated that at threshold values lower than 400,000 the current evidence supported the use of on-demand therapy. Threshold values higher than 1,000,000 supported the use of tailored or alternate day prophylaxis. At threshold values between 400,000 - 1,000,000 the optimal decision varied from on-demand to prophylaxis therapies. Conclusions. New, more powerful and acceptable designs should be developed for rare diseases. When time-to-event outcomes are used, investigators should use various sources of information to evaluate response time distributions before the new trial is designed, and consider this information in sample size calculation and analysis. VOI methodology should be used in the planning stage of studies to determine the relevant costs and benefits of future research, and to determine the optimal trial parameters that maximize the cost-benefit trade-off.