VictorJuiz/thesis huggingface dataset:
Understanding the Factors that Influence Headwater Stream Flows in Response to Storm Events

I studied how geology, land use and rainfall, correlated with peak flow responses in 110 headwater stream sites during a drought year. Highest discharges were observed in the most developed catchments and in the most poorly drained soils, but specific responses were variable depending on both geology and land disturbance. Redundancy analysis indicated that both surficial geology and land disturbance were important predictors of discharge and that rainfall was in general a poor predictor of discharge. I conclude that responses of headwater streams to individual storms are unpredictable from data generated using GIS, but increased peak flows occur associated with human development, mitigated by surficial geology. The headwater streams that are most vulnerable to flow alterations occur on poorly drained soils, and where urbanization tends to concentrate. Much greater attention to managing water is required if further degradation of stream ecosystems is to be prevented from our future land use.

Keywords: headwater
flows
streams
impacts
flashiness
rainfall
Ontario
discharge
Advisor: Jackson, Donald Andrew
Luminescence Contact Imaging Microsystems

This thesis presents two hybrid luminescence-based biochemical photosensory microsystems: a CMOS/microfluidic chemiluminescence contact imager, and a CMOS/thin-film fluorescence contact imager. A compact, low-power analog-to-digital converter (ADC) architecture for use in such sensory microsystems is also proposed. Both microsystems are prototyped in a standard 0.35um CMOS technology. The CMOS/microfluidic microsystem integrates a 64x128-pixel CMOS imager and a soft polymer microfluidic network. Circuit techniques are employed to reduce the dark current and circuit noise for low-level light sensitivity. Experimental validation is performed by detecting luminol chemiluminescence and electrochemiluminescence. The CMOS/thin-film microsystem integrates an existing 128x128-pixel CMOS imager and a prefabricated, high-performance optical filter. Experimental validation is performed by detecting human DNA labeled with Cyanine-3 fluorescent dye. The proposed ADC architecture employs a novel digital-to-analog converter with a flexible trade-off between the integration area and the conversion speed. The area savings and good linearity of the DAC are verified by simulations.

Keywords: Chemiluminescence
CMOS imager
Electrochemiluminescence
Fluorescence
data converters
analog-to-digital converters
microfluidics
Advisor: Genov, Roman
Seismic Performance of Steel Moment-resisting Frames with Nonlinear Replaceable Links

This thesis presents the development and the seismic performance evaluation of steel MRFs with nonlinear replaceable links. Although existing MRFs can provide life safety during a design level earthquake, they are expected to sustain significant damage at the locations of flexural yielding fuses in the beams. The design of the fuse is also interlinked with the design of the beam, often resulting in over-design. These drawbacks can be mitigated by introducing replaceable links at the locations of expected inelastic action. Four full-scale beam-to-column subassemblages with two link types were tested under cyclic loading: i) double channels with bolted web connections, ii) W-sections with bolted end plate connections. The experiments demonstrated that MRFs with replaceable links can provide strength and ductility equivalent to existing MRFs. Finite element models were then developed to capture the observed experimental responses, including local buckling, bolt slipping, and bolt bearing. Finally, preliminary design guidelines were proposed.

Keywords: MRF
Replaceable Links
Steel Frames
Seismic Connections
Advisor: Christopoulos, Constantin
Examining the Layout and Organization of the Air Ambulance Patient Care Environment to Improve the Workflow of Paramedics and the Safety of Patients

The purpose of this research was to examine physical layout and organization of equipment as it pertained to patient care in rotor-wing air ambulances. The qualitative approach included observations, interviews, surveys and incident report reviews; and involved paramedics, educators, engineers and physicians affiliated with Ornge Transport Medicine. Findings showed that there is inconsistent placement of equipment within and between bases. A standardized approach to storing equipment, including labelling, could improve readiness for a call by assisting paramedics in ensuring equipment is properly stocked. It was also found that the layout of the patient care compartment was not optimal for some tasks, such as intubation and documentation, due to lack of space. Future helicopters should have seating, both behind the head and at the side of the patient that accommodates safe postures and allows paramedic’s access to the supplies necessary for the full spectrum of patient care expected in this environment.

Keywords: pre-hospital
air ambulance
paramedic
patient safety
human factors
Advisor: Easty, Anthony
Photoreactions of Chlorophyll at the Salt Water-air Interface

Glancing angle laser induced fluorescence was used to monitor the kinetics of the photodegradation of chlorophyll at the surface of various salt solutions. The loss was measured using varying wavelengths of actinic radiation in the presence and absence of gas phase ozone. The loss rate of illuminated chlorophyll was faster on salt water surfaces than fresh water surfaces, both in the presence and absence of ozone. On salt water surfaces, the dependence of the loss rate on [O3(g)] was different under illuminated conditions than in the dark. This was further investigated by measuring the excitation spectra and the dependence of chlorophyll loss on the concentration of salts at the salt water surface. The possible production of reactive halogen atoms is the likely reason for the observed enhancement. The following results provide evidence of photosensitized oxidation of halogen anions, in the UV-visible range of the spectrum, resulting in halogen atom release.

Keywords: chlorophyll
air-water interface
surface microlayer
halogens
sea salts
marine boundary layer
Advisor: Donaldson, D. James
Delayed Oxidative Injury to the Superior Colliculus and Retinal Changes After Cerebral Hypoperfusion/Reperfusion Injury

Damage to visual pathways can lead to irreversible blindness. Posterior visual pathways, located within a watershed area, are predisposed to hypoperfusion/reperfusion injury. In a novel rat model of bilateral common carotid artery occlusion (BCCAO), oxidative injury to the superior colliculus (SC), a major visual center within the watershed area was evaluated, in addition to its effects on retinal ganglion cells (RGCs). Nitrotyrosine, a footprint of peroxynitrite-mediated oxidative injury in the SC, and microtubule-associated protein 2, a dendrite marker in the retina, were assessed using immunofluorescence and confocal microscopy. Nitrotyrosine-immunoreactivity in the SC was increased 2 weeks after BCCAO compared to controls. Microtubule-associated protein 2-immunoreactivity in the central inner plexiform layer was reduced 3 weeks after BCCAO compared to controls. Global incomplete cerebral hypoperfusion/reperfusion induced oxidative injury in the SC and retrograde RGC dendritic changes. This suggests that cerebrovascular injury affecting the posterior visual pathways may contribute to vision loss in patients.

Keywords: bilateral common carotid artery occlusion
superior colliculus
nitrotyrosine
rodent
retinal ganglion cell
stroke
Advisor: Yucel, Yeni
Gupta, Neeru
On the Resilience of Network Coding in Peer-to-Peer Networks and its Applications

Most current-generation P2P content distribution protocols use fine-granularity blocks to distribute content in a decentralized fashion. Such systems often suffer from a significant variation in block distributions, such that certain blocks become rare or even unavailable, adversely affecting content availability and download efficiency. This phenomenon is further aggravated by peer dynamics which is inherent in P2P networks. In this thesis, we quantitatively analyze how network coding may improve block availability and introduce resilience to peer dynamics. Since in reality, network coding can only be performed within segments, each containing a subset of blocks, we explore the fundamental tradeoff between the resilience gain of network coding and its inherent coding complexity, as the number of blocks in a segment varies. As another application of the resilience of network coding, we also devise an indirect data collection scheme based on network coding for the purpose of large-scale network measurements.

Keywords: Peer-to-Peer
Content Distribution
Network Coding
File Sharing
Churn
Measurement Collection
Coding Complexity
Loss Resilience
Data Collection
Log Collection
Avalanche
BitTorrent
Generation
Segment
Advisor: Li, Baochun
Electrophysiological Events Related to Top-down Contrast Sensitivity Control

Stimulus-driven changes in the gain of sensory neurons are well-documented, but relatively little is known about whether analogous gain-control can also be effected in a top-down manner. A recent psychophysical study demonstrated that sensitivity to luminance contrast can be modulated by a priori knowledge (de la Rosa et al., in press). In the present study, event-related potentials were used to resolve the stages of information processing that facilitate such knowledge-driven adjustments. Groupwise independent component analysis identified two robust spatiotemporal patterns of endogenous brain activity that captured experimental effects. The first pattern was associated with obligatory processing of contextual information, while the second pattern was associated with selective initiation of contrast gain adjustment. These data suggest that knowledge-driven contrast gain control is mediated by multiple independent electrogenic sources.

Keywords: top-down
electroencephalography
independent component analysis
partial least squares
contrast sensitivity
event-related potentials
sensory gain
contrast gain
Advisor: McIntosh, Anthony Randal
Interaction of hERG Channels and Syntaxin 1A

The human ether-à-go-go related gene (hERG) encodes the pore-forming voltage-gated K+ channel that is essential for cardiac repolarization. Dr. Tsushima’s laboratory has previously characterized the endogenous expression of SNARE proteins in the mammalian heart, and the interaction of the SNARE protein syntaxin 1A (STX1A) with several cardiac ion channels. Here, we utilize a multi-disciplinary approach to describe the inhibitory effect of STX1A on hERG channel function. STX1A impairs hERG channel maturation and trafficking to the plasma membrane and induces a hyperpolarizing shift in the voltage-sensitivity of steady-state inactivation. We identify the residues involved in this protein-protein interaction through the use of hERG truncation mutations. We also describe the pharmacological and temperature-mediated rescue of hERG channel trafficking in the presence of STX1A. The regulation of cardiac ion channels by SNARE proteins represents a novel biological mechanism that may have universally intrinsic implications for normal and diseased heart function.

Keywords: cardiovascular
molecular biology
electrophysiology
protein trafficking
ion channel
protein-protein interaction
patch clamp
hERG
SNARE
syntaxin
Advisor: Tsushima, Robert G.
The Effects of Salvia hispanica L. (Salba) on Postprandial Glycemia and Subjective Appetite

Dietary interventions have been attempted to lower the risk of obesity, diabetes and CVD by the reduction of postprandial hyperglycemia and prevention of excess caloric intake. Evidence suggests an independent predictive role of postprandial glycemia for CVD. Furthermore, due to the possible role of obesity in the development of CVD and T2D, research has focused on appetite suppression to reduce excessive food intake. Here we investigate the ability of the novel oil-rich grain Salvia hispanica L. (Salba) to lower postprandial glycemia and reduce appetite when added to a carbohydrate meal. In our first study, we investigated the effects of Salba in escalating doses on both parameters in healthy individuals. In our second study we compared the effectiveness of ground and whole forms of Salba on the same parameters. Results confirmed our hypotheses, as Salba given in either form positively affected postprandial glycemia and mildly suppressed

Advisor: Vuksan, Vladimir
Contributions of Central and Peripheral Vision to the Control of Reach-to-Grasp Reactions Evoked by Unpredictable Balance Perturbation

This thesis presents two studies that investigate how vision is used to control rapid, compensatory reach-to-grasp reactions. Compensatory grasping reactions were evoked in healthy young adults via unpredictable translations of large platforms on which the subjects stood or walked. The first study tracked natural gaze behaviour during responses to unexpected balance perturbations. It provided evidence that, unlike with voluntary movements, the eyes do not lead the hand during balance recovery – subjects relied on ‘stored’ information from central vision, continuously-available peripheral vision, or a combination of these sources to guide the hand. The second study investigated the efficacy of reliance on peripheral vision to guide rapid reach-to-grasp balance-recovery reactions. Peripheral vision was found to guide reach-to-grasp responses with sufficient accuracy to achieve a functional grasp of a relatively small handhold; however, peripherally-guided movements were slower when the handhold was in the extreme periphery.

Keywords: postural balance
falls prevention
reaching
grasping
peripheral vision
central vision
gaze behaviour
Advisor: Maki, Brian Edward
An Event-related Potential Investigation on Associative Encoding and the Effects of Intra-list Semantic Similarity

Event-related potentials were recorded as subjects were presented with pairs of words, one word at a time, to examine the electrocortical manifestations of association formation and the effect of intra-list semantic similarity. Two types of lists were presented: Same – all pairs belonged to the same semantic category; Different – all pairs belonged to a different semantic category. Subjects were told to memorize the pairs for a following paired associate recall test. Recall was better for the Different than Same lists. Subsequent recall was predicted by the amplitudes of a potential lasting throughout the epoch and the P555 to each word of a pair (likely reflecting state- and item-related encoding activity, respectively), as well as a late positive wave that occurred after the offset of the second word, which is thought to reflect association formation. A larger N425 was elicited by pairs in the Different than Same lists, likely reflecting semantic integration.

Keywords: association formation
event-related potential
intra-list semantic similarity
P555
N425
late wave
Advisor: Picton, Terence W.
Tulving, Endel
Novel Formulations of Antioxidant and Anti-inflammatory Drugs to Ameliorate Ischemic Damage Measured In Vitro

The two of major pathways that cause ischemic damage are oxidative stress and inflammation. To decreasing oxidative stress and inflammation, new anti-oxidant and anti-inflammatory agents are tested in ischemic models. In order to study ALRX828C anti-inflammatory properties, an in vivo six-day old air pouch model of inflammation was used to evaluate the anti-inflammatory potential of ALRX828C. Also, the dose response of ALRX828C for TNFα (IC50 = 30 μM) and IL-17 (IC50 = 1.3 μM) were determined by using human peripheral blood mononuclear cell cultures stimulated with ionomycin and PMA. To examine ALRX828C anti-inflammatory effect in neuroinflammation, a neurodegenerative model was used to evaluate its potential. I also showed that reducing oxidative stress with a potent antioxidant, Idebenone in nano-emulsion form, can effectively reduce tissue damage during ischemia in organotypic slice culture subjected to oxygen-glucose depravation (OGD). In conclusion, reducing oxidative stress and inflammation after stroke can reduce ischemic damage substantially.

Keywords: Neuroinflammation
Ischemia
Advisor: Carlen, Peter Louis
Aerostructural Optimization of Non-planar Lifting Surfaces

Non-planar lifting surfaces offer potentially significant gains in aerodynamic efficiency by lowering induced drag. Non-aerodynamic considerations, such as structures can impact the overall efficiency. Here, a panel method and equivalent beam finite element model are used to explore non-planar configurations taking into account the coupling between aerodynamics and structures. A single discipline aerodynamic optimization and a multidisciplinary aerostructural optimization are investigated. Due to the complexity of the design space and the presence of multiple local minima, an augmented Lagrangian particle swarm optimizer is used. The aerodynamic optimum solution found for rectangular lifting surfaces is a box wing, while allowing for sweep and taper yields a joined wing. Adding parasitic drag in the aerodynamic model reduces the size of the non--planar elements. The aerostructural optimal solution found is a winglet configuration when the span is constrained and a wing rake when there is no such constraint.

Keywords: Aero-structural Desgin
Multidisciplinary Optimization
Numerical Optimization
Non-planar Lifting Surfaces
Advisor: Martins, Joaquim R. R. A.
Stereoscopic PIV In Steady Flow Through a Bileaflet Mechanical Heart Valve

The tendency of aortic bileaflet mechanical heart valves (BiMHVs) to promote thrombosis has been well documented in the literature. The relationship of thrombosis to valve fluid dynamics has prompted numerous studies of aortic BiMHV flow. In this study, steady flow was investigated downstream of a model Carbomedics No. 25 BiMHV in an axisymmetric aortic sinus using stereoscopic particle image velocimetry (SPIV). The Reynolds number based on inlet diameter was 7600, and the measurement plane was perpendicular to the leaflet axes at the centerline of the aortic sinus. The typical formation of three jets was observed: the upper and lower lateral orifice jets, and the central jet. Flow separation from the valve ring was seen, and large scale vortices were identified in both the upper and lower sinus regions. An asymmetry in the reverse flow was found, and possible causes were discussed. All three jets were seen to decay similarly to free rectangular jets, with zero decay initially, followed by a 'linear' decay rate in which Umax^2~X. The central jet was also seen to be self similar in the linear decay region. Analysis of the out-of-plane velocity yielded two alternate explanations of streamwise vortex (i.e. Wx) structure, with either a four-cell or an eight-cell streamwise vortex structure being present in the mean velocity field. Organization of large scale three dimensional flow structures was thus apparent. Calculation of in-plane Reynolds stresses showed that values were highest in the outer shear layers of the lateral orifice jets. Elevated Reynolds shear stress values were also found in the leaflet wake regions, and the shear layers of the central jet.

Keywords: stereoscopic particle image velocimetry
bileaflet mechanical heart valve flow
PIV image dewarping
Advisor: Ethier, C. Ross
Sullivan, Pierre E.
Functional Outcomes in the Aged with Hip Fractures: A Systematic Review of Randomized Clinical Trials

Hip fracture trials have used a wide range of patient-reported outcomes (PRO) suggesting a lack of consensus among clinicians on what are considered the most relevant functional outcomes. We conducted a systematic review to identify the outcomes used in hip fracture randomized controlled trials (RCTs). We hypothesized that there had been an increase in numbers of PROs over time and the health status measure, SF-36, would be used the most. A database search and screening yielded 86 original trials. The mean Detsky score (and standard error) for quality was: 75.8% ± 1.76%. There was a trend in the increase of functional outcome; however, the SF-36 was used only in (10 out of 86) 11.6% trials. Both the ADL-Katz Index and HHS have lower respondent burden than the SF36 which may contribute to their frequent use in hip RCTs. There is a lack of applicable measures suitable for patients with dementia.

Keywords: hip fracture
measurement
Advisor: Schemitsch, Emil H.
The Closed Circle of Empathy: Mirror Neuron System Activation and Anterior EEG Asymmetries in Response to Outgroup Members

Empathy varies with similarity and familiarity of the other. Since outgroups are seen as dissimilar to the self, empathy might be restricted to the ingroup. We looked at two neural correlates of empathy: mirror neuron system activation as indicated by electroencephalographic mu suppression and prefrontal alpha asymmetry. Non black participants watched videos of ingroup and outgroup members acting and expressing emotions, and then acted and experienced emotions themselves. Due to methodological problems, mirror neuron system activation was not obtained. However, anterior asymmetries indicated avoidance motivation during the experience of sadness and the mere observation of sad ingroup members while participants did not show anterior asymmetry when observing the black outgroup. These findings suggest that empathy is bounded to a closed circle of similar others.

Keywords: Empathy
Prejudice
Mirror Neurons
Prefrontal Alpha Asymmetry
Advisor: Inzlicht, Michael
Plaks, Jason
On Large-scale Peer-to-peer Streaming Systems

Peer-to-peer (P2P) streaming has recently received much research attention, with successful commercial systems showing its viability in the Internet. Despite the remarkable popularity in real-world systems, the fundamental properties and limitations are not yet well understood from a theoretical perspective, as there exists a significant gap between the fundamental limits and the performance achieved in practice. In this thesis, we seek to provide an in-depth analytical understanding of fundamental properties and limitations of P2P streaming systems, with a particular spotlight on the performance gap. We first identify the major problem in existing streaming protocols and show that this problem accounts for most of the gap separating the actual and optimal performances of the streaming systems. We then propose a remedy based on network coding to address this problem and show that the gap to the fundamental limits can be significantly reduced.

Keywords: Computer Networks
Peer-to-Peer Networks
Peer-to-Peer Streaming Systems
Advisor: Li, Baochun
Phonetic Discrimination in the First and Second Half-year of Life: An Investigation of Monolingual and Bilingual Infants using Event-Related Functional Near-infrared Spectroscopy (fNIRS)

How do infants learn the sounds of their native language? Do they need to use general-auditory or language-specific mechanisms to make sense of the distributional nature of their phonetic input? To answer this question, this study investigated the neural correlates of phonetic discrimination in monolingual and bilingual infants (2-6 and 10-14 months) and adults using a new lens afforded by functional Near-Infrared Spectroscopy (fNIRS) neuroimaging. All participants heard syllables phonetically contrastive in their native English and Hindi (non-native) in an oddball paradigm while being imaged with fNIRS. Age comparisons of infant brain activation in multiple sites revealed that left Broca‟s area showed a developmental decline in response to native-language experience only. Bilateral STG showed robust recruitment at both ages in response to both stimulus languages. These findings were robust across monolinguals and bilinguals. Together, the results suggest that all infants use neural tissue predisposed for linguistic-phonetic processing in early life.

Keywords: Infant
Brain
Language
Bilingual
fNIRS
Phonetic
Discrimination
Advisor: Petitto, Laura-Ann