VictorJuiz/thesis huggingface dataset:
Adolescent Compliance with Oral Hygiene Instructions during Fixed Orthodontic Treatment: A Pilot Study
Keywords: Orthodontics
Compliance

Objectives: To determine compliance with oral hygiene instructions (OHI) of adolescents receiving two-arch fixed orthodontic treatment in a graduate orthodontic clinic and to identify predictive factors. Methods: Forty-one patients in a longitudinal pilot study were provided standardized OHI and assessed at baseline: before bonding (T1); 30 days after (T2), and 150 days after bonding (T3). Oral hygiene was measured using plaque and gingival indices. Compliance predictors were identified from questionnaires and patient records. Results: Good compliers increased from 10 at T1 to 29 at T3. Univariate analyses found perceived severity of malocclusion, school performance and parental marital status to be significant predictors. Multiple logistic regression identified having married parents and good school performance as significant predictors. Conclusions: In the sample studied, after initially worsening, compliance with OHI improved at five months after bonding. Adolescents with married parents and those reporting good academic performance in school were more likely to comply.
Developmental Regulation of the type-A Gamma-Aminobutyric Acid Receptor (GABA-AR) Signaling in the Fetal Rat Lung
Keywords: Lung Development
Type-A Gamma Aminobutyric Acid Receptor (GABA-AR) and Glutamic Acid Decarboxylase (GAD) in Fetal Lungs
Fluid Secretion in the Mammalian Lungs
Cell and Molecular Biology

The fetal lung epithelium secretes fluid into the potential pulmonary air-spaces by actively transporting chloride (Cl¯) into the lung lumen. This Cl¯-driven fluid secretion declines with the progression of lung development. Recent studies demonstrate that the A-type γ-aminobutyric acid receptor (GABAAR), a Cl¯ channel, and glutamic acid decarboxylase (GAD65/67), key GABA-synthesizing enzymes, are expressed in adult pulmonary epithelial cells (ECs), forming an autocrine GABAAR signaling system. My thesis study revealed that GABAAR π- and β2- subunits are expressed in high levels in the fetal rat lung epithelium and decline at birth, consistent with pattern of fluid secretion. Immunohistochemistry showed distinct profiles of expression for GABAAR subunits and GAD65/67. Treatment of alveolar ECs with dexamethasone reduced the GABAAR π-subunit expression. These results suggest that the GABAAR signaling in the fetal pulmonary epithelium is developmentally regulated and the GABAAR expression and GABAAR-mediated Cl¯ secretion in pulmonary ECs may be regulated by glucosteroids.
Is Depression Associated with Edentulism in Canadian Adults?
Keywords: edentulism
depression
older adults

It has been hypothesized that depression can be both a risk factor and a consequence of oral diseases. Tooth loss leads to discomfort, pain, and functional limitations which could lead to disability and, subsequently, to handicap. However, the association between depression and edentulism has not been established yet. Data from the Canadian Community Health Survey (CCHS) Cycle 2.1 were used to examine the association between edentulism and depression in community-dwelling Canadians 45 years of age and older. Separate logistic regression models were developed for dentate and edentulous groups as well. Different regression selection methods were implemented and the area under the ROC curve was used to select models with the highest predictability. Analysis showed that edentulism was not associated with depression. For the edentulous group, oral/facial pain was the only oral health factor predicting depression, whereas avoiding smiling or laughing, dry mouth, oral/facial pain predicted depression in the dentate individuals.
2 2D Model of Semi-molten Drop Impact for Thermal Spray Application
Keywords: thermal spray
model
semi-molten particle
IB and VOF method

In thermal spraying, semi-molten (or partially-melted) particles are likely to form when the sprayed particles are insufficiently heated, or when a composite material is deposited. The present 2D model serves to begin to assess the spreading behavior of a semi-molten particle when impacting a solid substrate. An Immersed-Boundary (IB) scheme was implemented in an axisymmetric fluid model to simulate fluid flow in the presence of a solid core. The IB method calculates a forcing term, which is added to the momentum equation, to enforce the no-slip boundary condition at the core surface. Results are presented for the impact of a semi-molten tin droplet of radius R for a wide range of solid core radii r, varying the drop size ratio r/R, and the impact velocity Uo.
Ectopic Notch Activation in Developing Podocytes Impairs Slit Diaphragm Formation and Induces Abnormal Podocyte Differentiation
Keywords: Notch
glomerulosclerosis

Podocytes are terminally differentiated epithelial cells which regulate glomerular permselectivity by their cell-cell junctions, known as slit diaphragms (SD). Notch signaling regulates podocyte cell fate specification and downregulation of Notch targets occurs with terminal podocyte differentiation. The effects of constitutive Notch activation in developing podocytes on podocyte differentiation and function were determined using a podocyte-specific Cre-lox-p(Neph/Cre) approach. Proteinuria was noted shortly after birth denoting loss of glomerular permselectivity in transgenic mice (CRE;NIC mice). Histologic and molecular analyses of CRE;NIC-expressing mice at onset of proteinuria, show morphologic and cellular changes in podocytes including de-differentiation, proliferation and de novo expression of Pax2. Prior to onset of proteinuria, lower protein levels of key SD proteins are observed while SD mRNA expression is preserved in CRE;NIC mice. Consequently, constitutive Notch signaling in developing podocytes opposes terminal differentiation with deleterious consequences on SD assembly and thereafter, glomerular permselectivity.
Synthesis of Highly Functionalized Tetrahydroisoquinolines by a Palladium-catalyzed Domino ortho-Alkylation/Heck Reaction Sequence and Diastereoselective Aryne Diels-Alder Reactions
Keywords: Chemistry
Organic Chemistry
Catalysis
Palladium
Aryne
Benzyne
Diels-Alder

We report a palladium-catalyzed, norbornene mediated synthesis of tetrahydroisoquinolines via a domino ortho-alkylation/Heck reaction sequence. The desired products are obtained in moderate to excellent yields starting from readily available aryl iodides. The reaction conditions can be extended to the formation of tetrahydroisoquinolinones and tetrahydrobenzo[c]azepines. The reaction allows for sequential intermolecular and intramolecular ortho-alkylations. However, the product yields are higher with ortho-blocked aryl iodides, which simplify the domino process to one intramolecular ortho-alkylation and a Heck reaction. The Lautens group has previously reported diastereoselective aryne Diels-Alder reactions of benzyne with dienes supporting a chiral auxiliary at its terminal carbon. In an effort to extend this work and allow access to a wider variety of 1,4-dihydronaphthalenes, we attempted the synthesis of dienes supporting a chiral auxiliary at a central carbon. Chiral pyridyne precursors were also synthesized, in an attempt to vary the source of chirality in diastereoselective cycloadditions.
Closed Loop Control of the Ankle Joint Using Functional Electrical Stimulation
Keywords: Closed Loop Control
Functional Electrical Stimulation
Ankle Joint
Inverted Pendulum

The restoration of arm-free standing in paraplegic individuals can be accomplished with the help of functional electrical stimulation (FES). The key component of such a system is a controller that can modulate FES induced muscle contractions in real-time, such that artificially produced forces in the legs and abdominal muscles are able to generate stable standing posture. A 57 year-old individual with chronic ASIA-A (American Spinal Injury Association), T3/4 level spinal cord injury (SCI) participated in this study. The objective was to determine if a proportional-derivative (PD) or proportional-integral-derivative (PID) controller could be used to regulate FES induced muscle contractions in the ankle joint to allow it to maintain balance of the entire body during quiet standing, while exhibiting physiological dynamics seen in able-bodied individuals while doing so.
The Benthic Invertebrate Community of Lakes Previously Impaired by MiningI-related Acidification Near Wawa, Ontario
Keywords: acidification
benthic invertebrates

Iron mining began in Wawa, Ontario in the late 1800s and ceased in 1998. The sintering process of iron pyrite produced sulfur dioxide which led to the acidification of nearby lakes. Benthic macroinvertebrate samples were collected from lakes along a gradient of historical impairment in Wawa to examine the extent to which the benthos of the lakes would separate along the historical impairment gradient. The results show that the lakes are not separated along a gradient of impairment, and acid-intolerant taxa were collected in previously acidified lakes. There was no ameliorative intervention to combat the historical acidification and the observed recovery of water chemistry and benthos is entirely due to natural ecosystem processes. The two sampling methods (littoral kick sampling using a D-net and Hester-Dendy substrates) used to sample the benthos in these lakes can lead to substantial differences in the taxa collected.
Understanding the Factors that Influence Headwater Stream Flows in Response to Storm Events
Keywords: headwater
flows
streams
impacts
flashiness
rainfall
Ontario
discharge

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.
Luminescence Contact Imaging Microsystems
Keywords: Chemiluminescence
CMOS imager
Electrochemiluminescence
Fluorescence
data converters
analog-to-digital converters
microfluidics

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.
Seismic Performance of Steel Moment-resisting Frames with Nonlinear Replaceable Links
Keywords: MRF
Replaceable Links
Steel Frames
Seismic Connections

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.
Examining the Layout and Organization of the Air Ambulance Patient Care Environment to Improve the Workflow of Paramedics and the Safety of Patients
Keywords: pre-hospital
air ambulance
paramedic
patient safety
human factors

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.
Photoreactions of Chlorophyll at the Salt Water-air Interface
Keywords: chlorophyll
air-water interface
surface microlayer
halogens
sea salts
marine boundary layer

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.
Delayed Oxidative Injury to the Superior Colliculus and Retinal Changes After Cerebral Hypoperfusion/Reperfusion Injury
Keywords: bilateral common carotid artery occlusion
superior colliculus
nitrotyrosine
rodent
retinal ganglion cell
stroke

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.
On the Resilience of Network Coding in Peer-to-Peer Networks and its Applications
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

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.
Electrophysiological Events Related to Top-down Contrast Sensitivity Control
Keywords: top-down
electroencephalography
independent component analysis
partial least squares
contrast sensitivity
event-related potentials
sensory gain
contrast gain

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.
Interaction of hERG Channels and Syntaxin 1A
Keywords: cardiovascular
molecular biology
electrophysiology
protein trafficking
ion channel
protein-protein interaction
patch clamp
hERG
SNARE
syntaxin

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.
Contributions of Central and Peripheral Vision to the Control of Reach-to-Grasp Reactions Evoked by Unpredictable Balance Perturbation
Keywords: postural balance
falls prevention
reaching
grasping
peripheral vision
central vision
gaze behaviour

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.
An Event-related Potential Investigation on Associative Encoding and the Effects of Intra-list Semantic Similarity
Keywords: association formation
event-related potential
intra-list semantic similarity
P555
N425
late wave

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.