title: The study of saprophytic competence in Sinorhizobium meliloti

contributor:
Finan, Turlough
Biology

subject:
aromatic catabolism
genome
Sinorhizobium melitoli

abstract:
This thesis details a study of saprophytic competence in the Gram-negative bacterium Sinorhizobium meliloti, and comprises three main areas of research. The B-ketoadipate pathway is required for the catabolism of a wide range of aromatic compounds that are released into soil through the degradation of lignin. We demonstrate
that S. meliloti encodes enzymes associated with the protocatechuate branch of the B-ketoadipate
pathway within two operons (pcaDCHGB and pcaIJF) whose expression is regulated by the LysR-protein PcaQ and the IclR-type regulator PcaR, respectively. We show that purified PcaQ recognizes a motif with partial dyad symmetry (5' ATAACCN4-GGTTAA 3') positioned upstream of the pcaD promoter, and that this site is required for the regulated expression of pcaD in vivo. We report that PcaQ also regulates the expression of a protocatechuate-inducible ABC-type transport system that we infer is involved in the uptake of this aromatic acid, and we extend this analysis to identify PcaQbinding motifs in the genomes of a-,B-, and y-proteobacteria.

In addition to protocatechuate, S. meliloti may utilize hydroxyproline as an energy
source, as this amino acid is released into soil during the natural decay of plant tissue.
We demonstrate that S. meliloti encodes a hydroxyproline-inducible ABC-type transport
system that mediates the uptake of trans-4-hydrox-L-proline, as determined via growth
and transport assays.

As a more comprehensive method of examining saprophytic competence, we assayed the growth of S. meliloti upon inoculation into sterile bulk soil. We screened 40 S. meliloti strains carrying deletions within the pSymA or pSymB megaplasmids for growth in soil, and report that the majority of strains establish a stable population (greater than or equal to 10^8 cells g^(-1) soil) that persists for several weeks. In contrast, two S. meliloti strains exhibited
a decreased ability to colonize soil, indicating that loci within the deleted regions play a role in saprophytic competence.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Microbially-Aided SiO2 Biomineralization

contributor:
Warren, Lesley
Geography and Earth Sciences

subject:
microbial silification
biomineralize
silica reaction

abstract:
Microorganisms inhabiting silica solute-rich environments often show various degrees of
Si02 mineralization as a consequence of exposure to SiOrsaturated waters. As such, it has been
thought that microorganisms exert a prominent role in the immobilization of amorphous silica
phases. While this intimate spatial relationship of microorganisms and amorphous Si02 phases
are almost always observed in hot springs, the exact mechanisms by which microbes affect Si02
secondary mineral precipitation is still poorly understood. Further, available laboratory
investigations to date consistently showed that microbes do not significantly impact Si02
immobilization, suggesting that microbial silicification is a mere consequence of exposure to a
largely abiogenically-driven Si02 precipitation.

This study demonstrates that discernible microbially-mediated silicification can occur
under conditions where the potential for microbial opportunity to biomineralize is promoted.
Identification of the key geochemical requirements for biosilicification to occur include
thermodynamically favorable, but sluggish silica reaction kinetics associated with acidic
conditions, and the necessity for colloidal silica rather than dissolved silicic acid species. This
work provides the first results to bridge the apparent literature discrepancy between widespread,
in-situ observations of microbial silicification, and the inability to demonstrate a detectable
microbial effect in this process under well-constrained laboratory conditions.

Acid conditions promote microbial silicification by overriding the dominant repulsive
forces arising from charge similarities between Si02 and cell surfaces, via neutralization of
deprotonated surface silanol and carboxylic groups, respectively. Mechanistic consideration for
Si02 coordination to cell surfaces suggests direct chemical bonding of silanol to carboxylic
groups forming stable inner-sphere complexes largely insensitive to environmental perturbations.
This result indicates that microbially immobilized Si02 are more tenaciously-coordinated on cell
surfaces and not simply electrostatically-held.

Surface-dependent silicification showed higher Si02 mineralization propensities for
unmineralized microbial cells compared to silica-encrusted cell matrices. Moreover, the extent
and style of microbial Si02 mineralization is impacted by cellular level of metabolic activity.
These results suggest that a biological overlay may be discernible in microbially induced
biosilicification.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Integrating Optical Emitters into Silicon Photonic Waveguides

contributor:
Knights, A.P.
Engineering Physics

subject:
Silicon light emitters
optical waveguides
planar waveguides integration
Edge emission
photonic circuits

abstract:
This thesis reports work targeting the integration of Si light emitters with optical waveguides. Such integrated devices would find utility in a number of applications including telecommunications, optical interconnects, and biological and chemical sensors. Much research has been directed by others on how to improve the emission efficiency and achieve lasing in VLSI (very large scale integration) compatible sources. Here, the focus is on how such devices can be integrated with planar waveguides. Two enhancement techniques were selected for potential integration; defect engineering (DE), and Si nanocrystals (Si-nc) embedded in Si02• Defect engineered light emitting diodes (LEDs) made on silicon-on-insulator (SOI) and emitting at 1.1 μm were successfully demonstrated. In addition, surface photoluminescence from SOI was analyzed to account for interference from the SOI cavity. However, it was determined that the emission efficiency of defect engineered LEDs studied during the course of this work is below that which was reported previously, and that the fabrication procedure thus suffers from irreproducibility. Barring an enormous advancement in the DE technique, it is concluded that the emission efficiency is too small to make use of its integration potential.

A more successful approach was obtained from the Si-nc system fabricated using electron-cyclotron resonance plasma enhanced chemical vapor
deposition (ECR-PECVD). Optically pumped edge emitting devices were designed, fabricated and characterized. The devices are comprised of Si-ncs emitting at 800 nm, integrated with slab silicon nitride waveguides. This work is the first report of edge emission from Si-ncs integrated with silicon nitride waveguides. Edge emission and waveguide properties were characterized in the ~850 nm emission band of the Si-ncs. The edge emission was well described as a propagating mode, attenuated primarily by the Si-nc film. Propagation losses of a typical air/Si-nc/SiNx/Si02 waveguide were measured to be 11 ± 2 dB/cm and 20 ± 2 dB/cm at 850 nm in the TE and TM polarizations respectively. A wavelength dependent loss of -0.14 ± 0.03 dB/(cm*nm) was found to exist in the material loss of Si-nc films. In addition, the Si-nc films were found to undergo a partially recoverable photo-induced degradation of PL efficiency during exposure to pump light. Processing techniques compatible with both high efficiency Si-nc and low loss silicon nitride were developed and described. A two-sectioned photonic device was also designed, fabricated and characterized. The device contained an optically pumped Si-nc emitting waveguide section integrated with a low loss silicon nitride slab waveguide. The potential for optically pumped Si-nc emitters integrated with silicon nitride photonic circuits thus appears promising.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Unexpected Magnetic Properties of Preovskite-Based Transition Metal Oxides

contributor:
Greedan, John E.
Chemistry

subject:
transition metal oxides
powder X-ray diffraction
pillared perovskites
magnetic properties

abstract:
Various transition metal oxides with interesting magnetic properties (often based on the perovskite structure) were prepared using conventional solid-state methodologies and fully characterized using a variety of techniques such as powder X-ray diffraction, variable temperature neutron diffraction, SEM-EDS, TEM-EDS, SQUID magnetometry
and heat capacity measurements.

One family of compounds that was investigated intensively were the 'pillared perovskites'. In this structure type, perovskite-like layers of comer shared octahedra are separated. by about 10 A by diamagnetic edge-shared octahedral dimer 'pillars'. Despite this long distance between layers, long-range order is present in both the La5Re3Co016
and La5Re3Ni016 members. In fact, a new magnetic structure was discovered for the Ni compound consisting of ferromagnetically ordered layers, coupled antiferromagnetically.

In addition, for the first time, substitution of the 5+ ion within the layer was successful, yielding compounds with general formula, La5Re3-xTaxB016 (B =Mn, Fe, Co, Ni; x ~ 0.5). Surprisingly, despite replacing about half of the magnetic ions within the perovskite layers with non-magnetic tantalum, the materials had the same ordering temperatures and magnetic structures as their unsubstituted analogues. This observation is evidence that the longer interlayer coupling pathway is the key to long-range ordering in this structure type.

The lanthanum rhenium oxide, La3Re20 10, involves the edge-shared octahedral dimer 'pillar' unit from the pillared perovskite structure, but with one unpaired electron per dimer unit. Prepared for the first time by solid-state synthesis, and studied magnetically in depth, long-range order was evident at 18 K. Theoretical investigations hinted that the magnetic structure consists of antiferromagnetically coupled chains of dimers, coupled antiferromagnetically.

The magnetic properties of the double perovskite, SrLaRuNi06, were also explored for the first time. This study demonstrates the power of neutron diffraction at elucidating magnetic information, such as the ordering temperature and magnetic structure, despite the presence of a ferromagnetic impurity that dominated much of the
measurements.

The candidate's examination of the magnetism of the rock-salt oxides, Na2Cu2Te06 and Na3Cu2Sb06 has raised some controversy in the literature, as the exact nature of the one-dimensional order (either antiferromagnetic-antiferromagnetic or
antiferromagnetic-ferromagnetic alternating linear chains) is uncertain. Again, theoretical calculations and comparison with other magnetic data can aide in the ultimate understanding of the overriding magnetism.

This thesis has focused on the synthesis and study of transition metal oxides with interesting or unusual magnetic properties. In many cases, the compounds exhibited long-range magnetic order despite convoluted or non-existent magnetic superexchange pathways.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: X-Ray and Neutron Diffraction Studies of Strongly Correlated Electron Systems

contributor:
Gaulin, B.D.
Physics

subject:
neutron scattering
X-ray
atomic excitations

abstract:
This thesis is comprised of three original works presented in Chapters 4,5, and
6. The three projects are comprised of three different problems in condensed matter
physics, the commonality between the topics is the technique used to study the materials,
diffraction. Two of which are in the form of journal articles that have been
peer-reviewed and published in Physical Review B, while the third is that of an unpublished
work. The unpublished work is presented first and uses neutron scattering
techniques, while two published papers were performed using x-ray diffraction.

The neutron scattering experiments were performed by myself with the assistance
of William J .L. Buyers and B.D. Gaulin. These experiments were performed at
Chalk River Laboratories in northern Ontario. The x-ray scattering experiments were
carried out on the rotating anode x-ray laboratory at McMaster University and the
Advanced Photon Source in Argonne II. All data analysis was performed by myself
under the guidance of B.D. Gaulin.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Effects of Probiotics and Prebiotic Milk Oligosaccharides in Murine Models of Food Allergy

contributor:
Forsythe, Paul
Medical Sciences

abstract:
ABSTRACT

Introduction: Incidence of food allergy has increased in the recent years yet no treatment is available except for allergen avoidance; therefore, new therapies are in development involving probiotic bacteria and human milk oligosaccharides. Food allergy results from an unbalanced T helper cell population favouring Th2/Th1 cells. Human milk oligosaccharides (HMOs) and probiotic bacteria have been shown to modulate the immune system; therefore they might be proposed as potential therapies against allergic diseases. In this study, HMOs 2’ fucosyllactose and 6’ sialyllactose, and probiotic strains Lactobacillus reuteri DSM17938 and Lactobacillus rhamnosus JB-1 were used as treatments against ovalbumin-induced food allergy in mice.
Results: The effects of oral treatment with probiotics and prebiotics on anaphylactic symptoms induced by oral ovalbumnin (OVA) challenge in sensitized mice were investigated. Mast cell functions in response to oral HMO treatment were also measured in the passive cutaneous anaphylaxis model and direct effects on IgE mediated degranulation of mast cells were assessed. Daily oral treatment with 2’ fucosyllactose or 6’ sialyllactose attenuated food allergy symptoms including diarrhea and hypothermia. Treatment with HMOs also suppressed antigen induced increases in mouse mast cell protease-1 in serum and mast cell numbers in the intestine. These effects were associated with increases in the CD4+CD25+IL-10+ cell populations in the Peyer’s patches and mesenteric lymph nodes, while 6’ sialyllactose directly inhibited mast cell degranulation In-vitro, at high concentrations. Effects of direct probiotic treatment were less dramatic. Lactobacillus reuteri DSM17938 decreased diarrhea and mMCP-1 in the colon while increasing IL-10 production. While Lactobacillus rhamnosus JB-1 increased IL-10 and IFN-γ while decreasing TNF-α from stimulated splenocytes but had no effect on symptoms.
Conclusion: Our studies suggest that 2’ fucosyllactose and 6’ sialyllactose reduce the symptoms of food allergy through the induction of IL-10+ T regulatory cells and indirect stabilization of mast cells. Thus, human milk oligosaccharides may have greater therapeutic potential in food allergy than probiotic treatment.

abstract: Thesis

abstract: Master of Science in Medical Sciences (MSMS)


title: The Merciful and Compassionate God: Biblical Theology in an Islamic Context

contributor:
Boda, Mark J.
Christian Studies

subject: biblical, theology, Islamic, context, God, Christianity

abstract: The primary purpose of this study is to write a biblical theology in the form of commentary in an Islamic context. This study argues that since the Old Testament is Christian authoritative Scripture, its theological message must be a fundamental resource for writing a biblical theology in an Islamic context. This study uses the narrative of Exod 32-34 as an example of the rich contribution the theological message of narratives makes to biblical theology. The theological message of this narrative reveals powerfully the character of the biblical God in dealing with the crisis of worshiping the golden calf in an Islamic context. This study calls for a move from an apologetic defensive theology that merely requires answering explicit challenges that Islam has posed to Christianity through the centuries to a biblical theology that addresses the hermeneutical questions that arise from the rhetorical Islamic context.

abstract: Thesis

abstract: Master of Arts (MA)


title: A Worthy Cause: The Lord's Day in the Baptist Press Amongst Nineteenth-Century Upper Canadian Regular Baptists

contributor:
Heath, Gordon
Christian Studies

subject: A Worthy cause, nineteenth century, Baptist, Upper Canada, Lord's Day, Church

abstract: "A Worthy Cause" brings to life a topic never before researched on the nineteenth-century Regular Baptist position surrounding the preservation of the Lord's Day (also known as Sabbatarianism) in Upper Canada. Within nineteenth-century Evangelicalism in the province the crusade for the protection of the Lord's Day was preeminent among social reform initiatives. Canadian Regular Baptists in Upper Canada viewed the observance and celebration of the Lord's Day as vital and of paramount significance in the quest for social reform and religious piety. Viewing this topic through the lens of various newspapers that made up the Regular Baptist press, this thesis demonstrates why the Lord's Day was considered to be one of the most worthy causes among nineteenth-century Upper Canadian Regular Baptists. The thesis contends that Baptist support for the Lord's Day was rooted in a number of interrelated convictions: its scriptural, doctrinal and confessional significance, its observation strengthened personal holiness and the family unit, its desecration was harmful to society, and lastly, its observance would bring a blessing to the nation. The Baptist approach was especially unique in that Baptists, champions of the separation of Church and State and religious liberty, deviated from their evangelical counterparts when it came to the legal enforcement of the Lord's Day. The thesis is an original contribution to the social and intellectual history of Baptists and the province at large.

abstract: Thesis

abstract: Master of Arts (MA)


title: The Integrity of 2 Corinthians from a Linguistic Perspective: Is There a Text in These Meanings?

contributor:
Porter, Stanley E.
Westfall, Cynthia Long
Christian Theology

subject: integrity, 2 Corinthians, Systemic Functional Linguistics (SFL), Christian,

abstract:
 After surveying previous language-related claims about the integrity of 2 Corinthians, this study develops a definition of "text" using Systemic Functional Linguistics (SFL). According to SFL, a text is the structured realization of a context of situation involving: (1) a particular activity together with its concomitant interpersonal roles and relations; (2) a particular sphere of human experience; and (3) a particular mode of conveying information. Moreover, because each of these contextual parameters correlates with specific linguistic systems, a general linguistic analysis can be used to assess whether or not an apparant text does or does not encode a plausible context.

 Employing an analysis of progressive moves to explore what is being done and an analysis of semantic domains to explore what is being talked about (as well as some additional analyses of conjunctive relations, identity chains, and cohesive harmony), the present study proposes that the body of 2 Corinthians consists of five segments wherein leadership in enacted within the sphere of the Christian church. First, after expressing a positive disposition towards its readers, 2 Corinthians addresses Paul and Timothy's controversial behaviour, especially Paul's handling of Corinthian immorality (1:3-2:13). Second, it teaches the Corinthians how to respond when people criticize the Pauline mission (2:14-5:21 ). Third, it appeals for communal purity while also acknowledging some recent progress in this area (6:1-7:16). Fourth, it reports an unexpected development in Macedonia and explains the task to which its bearers have been appointed (8:1-9: 15). Fifth, it warns that discipline will be enacted upon Paul and Timothy's arrival if the Corinthians do not continue to maintain the purity of their congregation, and it attempts to shut down distracting leadership debates by denigrating the worldly leadership standards that are operative in those debates ( 10:1-13:10).

 Inasmuch as that these behaviours can be plausibly regarded as the sequential stages of a single, unfolding context of situation, this study concludes that 2 Corinthians is a single letter. Moreover, a number of exploratory suggestions are made with regard to the interpretive and historical implications of reading 2 Corinthians in light of this overarching context of situation.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: The Effect Of Wave Breaking On The Performance Of Tuned Liquid Dampers

contributor:
Hamed, Mohamed
Mechanical Engineering

subject:
wave breaking
Tuned Liquid Dampers

abstract: An in-house numerical model developed at McMaster University was used in this research to investigate the effect of the wave breaking on the performance of Tuned Liquid Damper (TLD). In this model, the Volume Of Fluid VOF method was used to construct the free surface and the surface tension was taken into consideration to evaluate the wave breaking. The model was implemented on incompressible, 2D flow water within the TLD that was harmonically excited. . The ability of the TLD to cancel out the external excitation was examined via damping effectiveness of the TLD. The damping effectiveness is calculated as the ratio of the net energy experienced by the TLD to the input excitation energy; both energies were calculated as the area under the force-displacement curve. The investigation of the effect of the wave breaking was done through changing the fluid height ratios, amplitude and frequency ratios. The fluid height ratio was changed as h/L= 0.5, 0.35, 0.125 which is above and at and below the critical fluid level for wave breaking occurrence respectively. The critical height is defined as the height at which the waves start to break. It was found that at high fluid ratios wave breaking did not occur, in contrary, at critical level wave breaking did occur and even more breaking waves recorded to have taken place at much lesser levels. The effect of the fluid height ratio on the damping effectiveness of the TLD was investigated, it was seen that the damping effectiveness of the TLD improves as water level becomes shallower. The amplitude ratio was also examined; the behavior of the TLD in general did not change i.e. increasing the amplitude enhances the damping of the TLD. The frequency ratio range was selected to cover the near-resonance region. It was found that the TLD damps most excitation close to the resonance. The wave breaking occurrence was assured via the free surface visualization for several cases and found in agreement with different wave breaking shapes reported experimentally.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Expel the Faithless Foe: Upper and Lower Canadian Clergy Discourse in the War of 1812

contributor:
Heath, Gordon L.
Studebaker, Steven M.
Christian Theology

subject:
Revolutionary War
War of 1812
England
United States
Presbyterians
Anglicans
Wesleyan Methodists
Upper Canada

abstract:
For Anglicans and Presbyterians, the Revolutionary War had proven the
"faithless" character of the American nation. The American Methodist focus on
individualism, exciting and loud worship, lack of educated clergy, enthusiasm, and perceived adherence to the Republican ideas dominant in the culture of the United States were viewed as antithetical to the more British focus on social responsibility, sober teaching, and adherence to the British king and constitution. With the 1812 declaration of war, the churches with stronger transatlantic connections were presented with powerful proof that their suspicions were based in reality and that the need to expel the faithless national foe of America from British soil coincided with the clerical need to expel the faithless doctrines of the Methodists as well. Whether critiquing the United States or the frontier religion that was deemed too similar in its teachings and practice, the Anglicans, Presbyterians and- to a lesser
extent-Wesleyan Methodists were constructing a ignore British version of British North American culture in order to combat what they perceived to be the growing threat of faithless, American values. These arguments found their impetus in the mixed composition of colonial inhabitants, the dubious loyalties of the American-born farmers in Upper Canada, and the events of the War of 1812. In order to unite such disparate peoples, the clergy defined and celebrated England's Christian character to demonstrate to that fragmented and diverse collection of inhabitants the benefits of being loyal subjects of God's empire rather than foolish citizens of a faithless nation.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: The "New Perspective" on Appraisal: Evaluation in the Book of Judges as Revealed by the Narrative Appraisal Model

contributor:
Boda, Mark J.
Porter, Stanley E.
Christian Theology

subject: book of Judges, Narrative, Appraisal, Model, YHWH,

abstract:
 The book of Judges fairly bristles with 'heroes' of ambivalent moral character,
and acts of dubious propriety, such as Gideon's use of signs to determine YHWH's will,
Jael's murder of Sisera, and the sacrifice of Jephthah's daughter. The terse narrative and
the reticent narrator frequently leave the ethical character of these actions in doubt. My
goal in this dissertation is to identify evidence available in the text, both literary and
linguistic, in order to evaluate the characters and actions of various participants in the
narratives of the "major" judges. On the basis of this evidence I will not only draw
evaluative conclusions about the characters of the judges and the Israelite people
themselves, but also about their varying perceptions of YHWH that these characters hold.

 In order to facilitate these goals, I will take an interdisciplinary approach. I will
employ the concept of narrative perspective from literary criticism and consider the
evaluative stance of the implied author, the narrator, and the various characters in the
narrative. I will also draw heavily on the Appraisal Theory of J. R. Martin and P.R.R.
White, which in turn derives from Systemic Functional Linguistics. By merging these
two approaches I will develop a new model which I call Narrative Appraisal which will
then be applied to the Hebrew text of Judges. The Narrative Appraisal Model can clarify
individual evaluative instances as well as patterns of linguistic features at the level of
discourse that elucidate the implied author's stance.

 The lexicogrammatical and ideational evidence produced by this methodology reveals contrasts and trajectories within and across the narratives which, when analyzed, give insight into the characters of the Israelites, the character of YHWH, and the relationship between the Israelite people and their God. It also helps to identify the unifying ideological stance of the book. In simplified terms, this ideology affirms the holiness, justice, mercy, and faithfulness of YHWH, the need for the Israelites to maintain absolute loyalty and obedience to him, the legitimacy of discipline, the engrained tendency of humanity to defy their God and follow their own ways, the ultimate failure of human leadership in the form of judges, and the essential need for YHWH to intervene with a new model of leadership.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: In Cadence with God: A Perichoretic Pastoral Theology

contributor:
Zylla, Phil
Beach, Lee
Christian Theology

subject: perichoretic, pastoral theology, spirituality, cadence, God

abstract: This dissertation is an attempt to construct a perichoretic pastoral theology. This constructive proposal comes through a conversation between central dimensions of pastoral theology and salient features of the doctrine of perichoresis. The conversation partners are: (1) theologies of experience and perichoretic relationality; (2) concern for human angst and perichoretic participation; and (3) situational attentiveness and perichoretic spirituality. This conversation yields a pastoral theology that is being called 'the practice of perichoresis.' The practice of perichoresis is a pastoral theology that helps ministering persons to navigate how their ministry practice can be done participatively (with God), attentively (in situations of ministry) and authentically (personal life and ministry). Spiritual polarities will be used to articulate this relational, participative and spiritual approach to pastoral theology. This perichoretic pastoral theology is articulated as three interrelated movements. The first polarity is the move from experience to relationship. The practices and methods pastoral theology uses to engage human experience is drawn into conversation with perichoretic relationality. This interaction encourages a move toward relationship in all pastoral theological work. The second polarity is the move from concern to presence. Here pastoral concern for human angst is drawn into conversation with perichoretic participation. This interaction encourages a move toward presence; a presence which hopes to disclose God's presence even in the most perplexing circumstances. The third polarity is the move from competence to communion. In this conversation pastoral theology's situational attentiveness is drawn into dialogue with perichoretic spirituality. The move toward communion encourages practices of situational attentiveness that are rooted in communion with God and within the community of faith. A fourth polarity is offered which incorporates the other three. It is the move from practice to prayer. Prayer is the practice that integrates the theological, contextual and personal dimensions of the practice of perichoresis. This perichoretic pastoral theology is constructed in the hope of helping ministering persons to live and minister in an ever-deepening cadence with the triune God.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: SALICYLATE ACTIVATES AMPK AND SYNERGIZES WITH METFORMIN TO REDUCE THE SURVIVAL OF PROSTATE AND LUNG CANCERS EX VIVO THROUGH INHIBITION OF DE NOVO LIPOGENESIS

contributor:
Steinberg, Gregory R.
Tsakiridis, Theodoros
Medical Sciences

subject: cholesterol, fatty acids, A549, H1299, mTOR, acetyl-CoA carboxylase (ACC), PC3, 22RV-1, Aspirin, metformin, proliferation, AMPK

abstract:
Background:  Aspirin, the pro-drug of salicylate, is associated with reduced incidence of death from cancers and is commonly prescribed in combination with metformin in individuals with type 2 diabetes. Salicylate activates the AMP-activated protein kinase (AMPK) via Ser108 of the AMPK β1 subunit, a mechanism that is distinct from metformin, which increases AMP:ATP. Many cancers have high rates of fatty acid synthesis and AMPK inhibits this pathway through phosphorylation of acetyl-CoA carboxylase (ACC).  It is unknown if targeting the AMPK-ACC-lipogenic pathway using salicylate and metformin may be effective for inhibiting cancer cell survival.
Results:  Salicylate suppresses clonogenic survival of prostate and lung cancer cells at therapeutic concentrations of aspirin. These clinically achievable concentrations of salicylate activated AMPK per the increasing phosphorylation of ACC and suppressing the activity of mTOR effectors kinase p70-S6 kinase and S6; effects that were enhanced with the addition of metformin and blunted in mouse embryonic fibroblasts (MEFS) deficient in AMPK β1. MEF cells deficient in AMPK β1 were more resistant to salicylates inhibitory effect on proliferation. Supplementation of media with fatty acids and mevalonate reverses the suppressive effects on cell survival indicating the inhibition of de novo lipogenesis is likely important.
Conclusions:  Salicylate increases ACC phosphorylation, reduces phosphorylation of mTOR targets and inhibits de novo lipogenesis in prostate and lung cancer cells, with concentrations of salicylate achievable through the ingestion of Aspirin (0.25-1.0mM) these effects are blunted in AMPK β1 deficient cells. Effects on AMPK activity via ACC phosphorylation as well as reductions in mTOR signalling targets and de novo lipogenesis are enhanced when used in combination with metformin. Suppressive effects on prostate and lung cancer cell survival are ameliorated when media is supplemented with mevalonate and fatty acids.  Pre-clinical studies evaluating the use of salicylates alone and with metformin to inhibit de novo lipogenesis and the growth of prostate and lung cancers are warranted.

abstract: Thesis

abstract: Master of Science (MSc)


title: Evaluating Retention and Capacity Building in Guyana's Surgical Training Program

contributor:
Grierson, Lawrence
Health Sciences

subject:
Program Evaluation
Guyana
Medical Education

abstract: In regions of the world that experience a deficit of surgical care, educational initiatives can foster the development of a skilled surgical workforce. Implicit in training these health workers is the mandate to retain them in the country in order build capacity. Eyal’s framework presents ways in which locally relevant training can improve retention and outlines the ethical and pragmatic concerns of such initiatives. In 2006, Guyana established it’s first surgical training program, an example of locally relevant training. The University of Guyana Diploma of Surgery (UGDS) program was selected for this case study research. Consistent data collection, supported by a systemic procedure to analyze that data, is paramount to increase the effectiveness of the UGDS program. The purposes of this dissertation research were two-fold. Firstly, it sought to understand how the UGDS program influences retention and the ways in which the UGDS members contribute to capacity building and the program’s sustainability. Secondly, this program evaluation provides a useful context to inform Eyal’s framework. 8 graduates, 2 trainees, 4 faculty members and 2 persons identified as policy makers were interviewed. Interviews were conducted face to face, and then transcribed. Surveys were administered to graduates and trainees and reflective journals were coded and analyzed. Overall, the data mapped fairly well onto Eyal’s framework. The results of the study suggest that the benefits and concerns Eyal outlines would be better represented along a continuum rather than being classified as either advantageous or disadvantageous with respect to retention. While Eyal’s claims generalize across settings, he should acknowledge this limitation and consider the important role that context plays. Overall, the results suggest that the UGDS program has positively influenced retention and capacity building. Key recommendations were made to the UGDS program that aim to improve retention and capacity building. As regions continue to face challenges associated with providing adequate surgical care, fostering retention and capacity building is recommended so that a sustainable surgical workforce can meet surgical needs.

abstract: Thesis

abstract: Master of Health Sciences (MSc)


title: Nitrogen Implanted α-SiC : A Correlation Between Electrical (C-V) Measurements and Damage Studies Using the Channeling Technique.

contributor:
Thompson, D.A.
Engineering Physics

subject: SiC, implanted, annealing, nitrogen, electrically, C-V,

abstract: Part A of two Project Reports; Part B can be found at: http://hdl.handle.net/11375/17691

abstract:
The annealing behaviour of 15N implanted, aluminum doped-SiC has been studied by measuring the differential capacitance as a function of applied bias. The samples were doubly implanted at 450°c with 45 Kev and 25 Kev ions, for a dose of 10^16/cm^2 at each energy.

 An n-i-p structure with a thick insulator region was found after annealing at 1000°c. The thickness of this i region could be substantially reduced with additional annealing at higher temperatures, and a fairly good n-p junction was obtained
after 1480°c anneal.

 About 20-30% of the implanted nitrogen ions were found to be electrically active.

 The C-V behaviour was found to have large variations with the a.c. measuring frequency.

abstract: Thesis

abstract: Master of Engineering (MEngr)


title: Advancements in the Field of Cardiovascular Disease Pharmacogenetics

contributor: Clinical Epidemiology/Clinical Epidemiology & Biostatistics

subject:
Epidemiology
Pharmacogenetics
Mendelian Randomization
Genetic epidemiology

abstract:
Background and Objectives: Pharmacogenetics has the potential to maximize drug efficacy and minimize adverse effects of cardiovascular disease (CVD) but its translation into clinical practice been slow. However, recent advancements in genotyping and statistical methodologies have now provided robust evidence in the support of personalized medicine. This thesis addresses how the advancements in pharmacogenetics may help to gain novel insights into existing drug targets, inform and guide clinical decision-making and validate potential disease target pathways.
Methods: This was achieved by exploring whether the COX-2 genetic variant (rs20417) is associated with a decreased risk of CVD outcomes, assessing whether bile acid sequestrants (BAS) are associated with a reduced the risk of coronary artery disease (CAD) using the principles of Mendelian Randomization and investigating whether genetic variants associated with dysglycaemia are associated with an increased risk of CAD.
Results: We demonstrated that COX-2 carrier status was associated with a decreased risk of major cardiovascular outcomes. Furthermore, we also showed that BAS appear to be associated with a reduced risk of CAD and genetic variants associated with HbA1c and diabetes were associated with an increased risk of CAD.
Conclusions: The convergence of technological and statistical advancements in pharmacogenetics have led to a more high-quality and cost-effective means of assessing the effect of CVD therapeutic agents.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: EXPLORING SYNTHETIC FUNCTIONAL DNA MOLECULES FOR BIOSENSOR DEVELOPMENT

contributor:
Li, Yingfu
Chemical Biology

subject:
DNAzyme
Aptamer
Biosensors
Functional Nucleic Acids

abstract: The development of the in vitro selection technique permits the creation of synthetic DNA molecules with ligand-binding capabilities (DNA aptamers), or abilities to catalyze chemical reactions (DNAzymes), or both (aptazymes). Significant research efforts in this field over the past two decades have led to the creation of a large array of DNA aptamers and DNAzymes and ever-increasing interests in taking advantage of these molecular species for diverse applications. One area of remarkable potential and development is the exploration of functional DNA molecules for bioanalytical applications. The work described in this dissertation aims to pursue innovative concepts and technologies that expand utility of functional DNA molecules for biosensing applications. I have focused on two functional DNA species: RNA-cleaving DNAzymes and protein-binding DNA aptamers. My key interest is to develop simple but effective colorimetric assays that employ these functional DNA molecules and to establish an effective strategy that makes functional DNA biosensors highly functional in biological samples.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Neurodevelopmental Outcomes in the Fragile X Mouse

contributor:
Foster, Jane
Neuroscience

subject:
brain development
genetic mouse model

abstract: Fragile X Syndrome (FXS) is a neurodevelopmental disorder and the most common heritable single gene cause of Autism Spectrum Disorder (ASD). The Fragile X (FMR1-KO) mouse model has been used to understand the pathophysiology of the disease. However, the majority of studies have been done in adult mice and early life outcomes have yet to be explored. Therefore, in order to contribute to the knowledge of the neurodevelopmental processes associated with brain disorders, this thesis examines postnatal outcomes in the Fragile X Mouse Model: early life behaviours, the developmental trajectory of a set of ASD risk genes, and neuroanatomical phenotype. The first study examined ultrasonic vocalizations in pups and showed a transient increase in calls in FMR1-KO mice. To understand the relationship between early life behaviours, the second study examined outcomes in the pre-pubertal period in these mice when challenged with lipopolysaccharide and maternal separation. The results showed genotype and treatment interactions affecting sexually dimorphic behavioural outcomes and developmental milestones. In the third study, possible underpinnings of behavioural differences were explored by examining mRNA expression of the neuroligins and neurexins. In FMR1-KO mice, changes were transient and sex-specific, suggesting these as molecular effectors in the disease. Lastly, using structural brain imaging, the fourth study examined regional volume differences that may be related to behavioural differences. Differences in regions affected in FXS patients were observed and genetic background was shown to affect the neuroanatomical phenotype. Overall, this thesis demonstrates that the FXS model recapitulates some outcomes in other ASD mouse models and shows that this single gene has multiple interactions with sex, strain, and postnatal challenge which manifests at specific ages at molecular, brain structure and behavioural levels. This work contributes to the efforts elucidating the neurobiology of ASD and reverse translation approaches to identify therapeutic targets for neurodevelopment disorders.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)

abstract: Autism spectrum disorder (ASD) is a diagnosis based on observed behaviours: impaired communication and repetitive actions. However, there are genetic and other behavioural differences in ASD patients that are not shared among the group. It is important to tease apart this group since current treatments for ASD do not target the biological problems or the core impairments. This thesis focuses on Fragile X Syndrome, the leading genetic condition that results in ASD in order to understand the biological basis of ASD. Using a mouse model, compared to healthy mice, these studies report changes in behaviours, in the size of different brain regions, and in molecules involved in connecting brain cells during development. These findings shed light on the molecular story underlying ASD. By understanding the nature of influences on the developing brain, the type and timing of interventions can be designed to keep the brain on a healthy trajectory.


title: Characterizing the cognitive, behavioural, and mechanistic actions of novel allosteric modulator PAOPA for the treatment of schizophrenia

title: PAOPA: Its behavioural, cognitive, and molecular effects

contributor:
Mishra, Ram
Neuroscience

subject: schizophrenia, dopamine, antipsychotic, allosteric modulator, PAOPA

abstract: The pathophysiology, etiology, and treatment of schizophrenia remain elusive, but research is closing the gap. Schizophrenia globally affects less than 1% of the population and presents with positive, negative, and cognitive symptoms. As treatment for schizophrenia is not completely and meaningfully effective at treating all of the symptoms, without eliciting side effects, the current thesis aimed to evaluate a new drug candidate. PAOPA is a novel allosteric modulator that increases dopamine binding to the dopamine D2 receptor. It has previously shown positive findings in preventing and reversing behaviours proposed to model phenotypes of schizophrenia. However, it has not yet been tested to improve cognitive deficits in animal models, nor has its effects on other animals models been investigated. Lastly, its mechanism of action has not yet been comprehensively answered. In three separate studies, PAOPA was tested on ameliorating attentional deficits using the 5-choice serial reaction time task in an amphetamine model, deficits in novel objection recognition memory, sensorimotor gating, social interaction, and locomotor activity using a PCP model, and its effects on proteins regulating G protein-coupled receptors (GRK2 and arrestin-3), downstream signalling (ERK1 and ERK2), and synaptic vesicular control (synapsin II) were investigated. Although the sample sizes were too small to draw valid interpretations, the results suggested that PAOPA partially attenuated deficits in attention, novel object recognition memory, social interaction, sensorimotor gating, but not locomotor. Furthermore PAOPA increased the protein expression of GRK2, arrestin-3, ERK1 and 2, and synapsin IIa in the medial prefrontal cortex, striatum, and the nucleus accumbens. The results suggest that PAOPA influences the dopaminergic system in the striatum to change behaviour via receptor internalization and possibly downstream signalling. The present studies illuminate new insights, and point to future explorations for the potential development of PAOPA as a therapeutic for schizophrenia.

abstract: Thesis

abstract: Master of Science (MSc)


subject:
Program Evaluation
Guyana
Surgical Education
Medical Education

abstract: In regions of the world that experience a deficit of surgical care, educational initiatives can foster the development of a skilled surgical workforce. Implicit in training these health workers is the mandate to retain them in the country in order build capacity. Eyal’s framework presents ways in which locally relevant training can improve retention and outlines the ethical and pragmatic concerns of such initiatives. In 2006, Guyana established it’s first surgical training program, an example of locally relevant training. The University of Guyana Diploma of Surgery (UGDS) program was selected for this case study research. Consistent data collection, supported by a systemic procedure to analyze that data, is paramount to increase the effectiveness of the UGDS program. The purposes of this dissertation research were two-fold. Firstly, it sought to understand how the UGDS program influences retention and the ways in which the UGDS members contribute to capacity building and the program’s sustainability. Secondly, this program evaluation provides a useful context to inform Eyal’s framework. 8 graduates, 2 trainees, 4 faculty members and 2 persons identified as policy makers were interviewed. Interviews were conducted face to face, and then transcribed. Surveys were administered to graduates and trainees and reflective reports and presentations were coded and analyzed. Overall, the data mapped fairly well onto Eyal’s framework. The results of the study suggest that the benefits and concerns Eyal outlines would be better represented along a continuum rather than being classified as either advantageous or disadvantageous with respect to retention. While Eyal’s claims generalize across settings, he should acknowledge this limitation and consider the important role that context plays. Overall, the results suggest that the UGDS program has positively influenced retention and capacity building. Key recommendations were made to the UGDS program that aim to improve retention and capacity building. As regions continue to face challenges associated with providing adequate surgical care, fostering retention and capacity building is recommended so that a sustainable surgical workforce can meet surgical needs.

abstract: Thesis

abstract: Candidate in Philosophy


title: A Narrative Study of a Community-Based Systems Navigation Role in an Urban Priority Neighbourhood

contributor:
Carter, Nancy
Nursing

subject: System Navigation, Health disparities, Community Health, Nurse Navigation

abstract: In response to the striking health and social inequalities existing across communities within a large Southern Ontario City the McMaster University School of Nursing has partnered with the local family health team, municipal government, and other community partners to evaluate a pilot program designed to enhance health and social outcomes within a specific priority neighbourhood. The innovative pilot program is a nursing-based system navigation role, grounded concurrently in the community and a local Primary Care Practice.  The role is uniquely designed as the nurse provides navigation for individuals and families while functioning as a networker to facilitate improved service integration at a systems level. This study serves as a narrative person-centered evaluation of the program, emphasizing the impact on the lives of community members. This study employed the Three-Dimensional Narrative Inquiry Space method as described by Clandinin and Connelly (2000) to explore the experience of nine community residents utilizing navigation services through the Community Nurse Navigator/Networker (CNN). Programs tell a story; therefore, the collection and analysis of participants’ life stories, in conjunction with field notes, observations, and documents, created a common narrative of the experience of navigation in a community setting. A thematic analysis of participants’ life stories was conducted to present a common narrative of community members’ experience of navigation. The major finding of this study was the positive experience residents shared interacting with the CNN. Participants valued the development of a therapeutic relationship through social interactions, the significance of place on the impact of the CNN role, and the effect of the navigation role to address health disparities over time. Study findings have implications for continued development of the CNN role and other community-based nurse navigation roles in priority neighbourhoods to address health inequities.

abstract: Thesis

abstract: Master of Science in Nursing (MSN)


title: FEASIBILITY OF MEASURING SELENIUM IN HUMANS USING IN VIVO NEUTRON ACTIVATION ANALYSIS

contributor:
Chettle, David R.
Medical Physics

subject: Selenium, Feasibility, IVNAA, 4-pi NaI(TI) detector

abstract:
Selenium (Se), an essential trace element, plays an important role in the normal function of a number of Se-dependent biological processes. Many studies have demonstrated that selenium deficiency in the body may contribute to an increased risk for certain neoplastic diseases (including colonic carcinoma, gastric carcinoma, pulmonary carcinoma and prostate carcinoma), as well as diseases of the cardiovascular, osseous, nervous systems and retardation of bone formation. However, at higher concentrations Se is cytotoxic. For these reasons it is desirable to have a means of monitoring selenium concentration in humans.
The feasibility of measuring selenium in humans using the in vivo neutron activation analysis (IVNAA) technique was studied. For this purpose human hand tissue equivalent phantoms were prepared with varying amounts of selenium and irradiated by a low energy neutron beam produced by the 7Li(p,n)7Be reaction by employing the high beam current Tandetron accelerator. The counting data saved using the 4π NaI(TI) detection system in anticoincidence, coincidence and singles modes of detection were analyzed. The selenium was detected via the neutron capture reaction, 76Se(n,γ)77mSe, whereas calcium was detected through the 48Ca(n,γ)49Ca reaction.
The peak areas of Se and Ca were computed and the Se concentrations were normalized to the Ca concentrations for various time segments of detection. The calibration lines were drawn between Se/Ca concentration and Se/Ca counts ratio. The minimum detection limits (MDL) were obtained and the inverse variance weighted mean value of MDL was finally calculated for three time segments. During the analysis of counting data it was also found that 18O is activated in water phantoms and becomes short lived radioactive 19O having T1/2=26.9 s.
To the author’s best knowledge, this study for the first time presents the MDL value in terms of Se/Ca concentration for the human hand bone equivalent phantom obtained from in vivo neutron activation analysis and these results will provide a good basis for future investigations.

abstract: Thesis

abstract: Master of Science (MSc)


title: LAND-BASED VECTOR MAGNETIC SURVEY  OF A BIF-HOSTED IRON ORE DEPOSIT,  MARY RIVER, BAFFIN ISLAND, NUNAVUT

title: LAND-BASED VECTOR MAGNETIC SURVEY OF BIF-HOSTED IRON ORE

contributor:
Boyce, Joe
Geography and Earth Sciences

subject: Ground-based vector magnetic survey, fluxgate magnetometer, iron ore deposit

abstract:
Banded iron formations (BIFs) are iron oxide- and silica-rich chemical sedimentary rocks and the principal source of high-grade (HG) iron ore. Magnetic survey methods are commonly applied in the exploration for BIF-hosted iron ore deposits but the interpretation of total magnetic intensity (TMI) data is often complicated by the presence of strong remanent magnetization and anisotropy of magnetic susceptibility (AMS). This study evaluated a tri-axial fluxgate vector magnetometer system for ground-based high-resolution mapping of BIF-hosted HG iron ore deposits at a 16 ha site near Mary River, Baffin Island. Magnetometer orientation was measured using a MEMS (Micro Electro-Mechanical System) accelerometer and dual D-GPS receivers. 12-oriented block samples were collected for analysis of rock magnetic properties and supplemented with outcrop measurements using a hand-held susceptibility probe.
The large (3 Gauss) dynamic range of the tri-axial vector magnetometer permitted mapping of HG magnetite ore zones, with TMI in excess of 400,000 nT. A 20 m-wide W-E trending HG zone and a narrow (<10 m) BIF zone were identified in RMV maps with distinctive dipole signatures. Within the HG zone a northwest-southeast oriented magnetic fabric was defined by linear magnetic lows that offset the strike of the HG ore zone and were interpreted as brittle faults or shear zones. The RMV orientation indicated the presence of strong bedding parallel magnetization, while its signal amplitude showed a wide variation between ore types and provided basis for ore grade differentiation. Paleomagnetic measurements revealed high Q ratios for hematite ores and strong AMS for BIF. The results from Mary River demonstrate that remanence and AMS effects are important in BIF-hosted iron ores and cannot be neglected in magnetic interpretation and inversion modelling of magnetic source bodies.

abstract: Thesis

abstract: Master of Science (MSc)


title: The Performance of SU-FREIs (Stable Unbonded - Fiber Reinforced Elastomeric Isolators)

contributor:
Drysdale, Robert G.
Tait, Michael J.
Civil Engineering

subject: Steel-reinforced elastomeric isolator bearings

subject: high manufacturing and installation costs

subject: lateral response behaviour

subject: fiber-reinforced elastometric isolator bearings

abstract:
 Steel-reinforced elastomeric isolator (SREI) bearings are currently the most commonly used type of seismic isolators. However, high manufacturing and associated installation costs prohibit their application in ordinary residential and commercial buildings. Fiber-reinforced elastomeric isolator (FREI) bearings are comprised of alternating layers of elastomer bonded to fiber-reinforcement layers. Research studies have shown that FREI bearings can be used as an alternative to SREI-bearings with comparable performance.

 FREis are much lighter in weight than traditional SREIs. In addition, their manufacturing cost can be lower, if individual FREI bearings, with the required size, are cut from a large sheet or a long strip, fabricated through mass production manufacturing techniques. An appealing application which simplifies the installation of FREI bearings is when they are placed between the substructure and superstructure with no bonding at their contact surfaces. This specific application is denoted as "unhanded application".

 When an unbonded FREI bearing is deformed laterally, it shows "rollover deformation" due to lack of flexural rigidity in the fiber-reinforcement sheets. The rollover deformation, as a beneficial feature, reduces the lateral stiffness of the bearing and enhances its seismic isolation efficiency, compared to the same bearing employed with bonded contact surfaces. However, it is important that the bearing is properly sized to maintain its lateral stability and hence exhibit ''stable rollover" (SR) deformation. Such a bearing is termed in this thesis as "stable unbonded" (SU)-FREI bearing.

 The main objectives of this research were to investigate the influence of geometry on the lateral response behavior of unbonded FREI bearings, and to evaluate the feasibility of employing SU-FREI bearings for seismic mitigation of low-rise buildings. The first objective was accomplished by conducting an experimental study on full-scale square FREI bearings. To achieve the latter objective a shake table study was performed on a 1/4 scale 2-storey steel frame which was seismically isolated with 1/4 scale SU-FREI bearings. The mechanical properties, including vertical and lateral stiffnesses and effective damping, of prototype samples of the 1/4 scale SU-FREI bearings were evaluated by vertical compression testing and cyclic lateral shear (under constant compression) testing. In addition, the influence of parameters such as lateral displacement amplitude and rate, amplitude history, and variations in the vertical pressure on the lateral response of the 1/4 scale SU-FREI bearings, were investigated.

 It was found that for FREI bearings having identical material properties and shape factor (the plan area of the bearing divided by the perimeter area of a single elastomer layer) the aspect ratio (length to total height of the bearing, also called second shape factor) plays an important role in achieving stable lateral response. All tested prototype 1/4. scale SU-FREI bearings exhibited SR-deformation with sufficient lateral flexibility and damping. Lateral response was found to be nonlinear and dependent on the amplitude and history of lateral displacement. However, due to the application of a relatively low design vertical pressure of 1.6 MPa, the influence of ±50% variation in the design vertical pressure on the lateral response was found to be insignificant. Lateral displacement capacity of the SU-FREI bearings was attained when their originally vertical faces fully contacted the upper and lower horizontal supports. This was accompanied with a significant increase in the lateral stiffness of the bearings which maintains the overall stability of the bearing to unexpectedly large ground motions. Shake table tests clearly demonstrated that SU-FREI bearings were efficient in seismic mitigation of the test-structure.

 The final component of this thesis involves investigating the applicability of two simplified
analytical models in seismic response prediction of a base isolated structure. The two models use different techniques to simulate the lateral load-displacement hysteresis loops of prototype SU-FREI bearings which are obtained from cyclic shear tests (under constant
compression). Model 1 includes the rate and the amplitude of bearings' lateral displacements to simulate the hysteresis loops through a multi-parameter curve fitting function. Model 2 uses bilinear idealization to simulate the hysteresis loops. Due to the highly nonlinear lateral response of SU-FREI bearings, these models utilize an iterative time
history analysis approach to improve their accuracy. Comparisons with shake table results of a 1A scale structure show that both models can be used in response prediction of ordinary structures which are seismically isolated with SU-FREI bearings.
.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: A WAVEFORM DIVISION MULTIPLEXING SCHEME FOR FIBER-OPTIC COMMUNICATION SYSTEM

contributor:
Xun, Li
Electrical and Computer Engineering

subject: orthogonal waveform multiplexing

abstract: A new multiplexing technique based on the orthogonality of the signal waveform is proposed. It can bring extra capacity to the existing fiber-optic communication system.

abstract: A new multiplexing technique is proposed in this work, which is a promising alternative technique for next-generation high-capacity fiber-optic communication system. The concept of this technique is based on the orthogonality of the signal waveform.

abstract: Thesis

abstract: Master of Science (MSc)

abstract: A number of signals with orthogonal waveforms are multiplexed into a single optical fiber. In this scheme, the user’s information is encoded into the amplitude and the phase of the signal waveform. Then multiplexed signals can be transmitted through the fiber-optic communication system.


title: High-speed silicon detector structures for photonic integrated circuits

contributor:
Knights, Andrew
Jessop, Paul
Engineering Physics

subject:
Silicon photonics
photodetectors
integrated optics
optoelectronic devices
silicon-on-insulator
waveguide
lattice defects

abstract:
Computing as a service is rapidly becoming the new normal for many sectors of the
economy. The widespread availability of broadband internet has allowed an extensive
range of services to be delivered on-demand from centralized computing systems known
as ‘data centers’. These systems have evolved to be enormously complex. Optical-based
communication is desired to increase data center capability and efficiency, however
traditional optical technologies are not feasible due to cost and size. Silicon photonics
aims to deliver optical communications on an integrated and affordable platform for use
in data centers by leveraging the existing capabilities of complementary metal-oxide
semiconductor manufacturing.
This thesis contains a description of the development of monolithic silicon
photodiodes for use in photonic integrated circuits in, and beyond, the current
telecommunications wavelength windows. The focus is on methods which are compatible
with standard silicon processing techniques. This is in contrast to the current approaches
which rely on hybrid material systems that increase fabrication complexity.
Chapter 1 and 2 provide background information to place this work into context.
Chapter 3 presents an experimental study of resonant devices with lattice defects which
determines the refractive index change in silicon-on-insulator waveguides. High-speed
operation of resonant photodiodes is demonstrated and is found to be limited by
resonance instability. Chapter 4 demonstrates high responsivity avalanche photodetectors
using lattice defects. The detectors are shown to operate error-free at 10 Gbit/s, thus
confirming their capability for optical interconnects. Chapter 5 presents photodiodes
operating with absorption through surface-state defects. These detectors show fast
operation (10 Gbit/s) and have an extremely simple fabrication process. Chapter 6
demonstrates photodiodes operating beyond the traditional telecommunications window.
Operation at 20 Gbit/s, at a wavelength of 1.96 µm is demonstrated, offering potential for
their use in the next generation of optical communication systems which will exploit the
thulium doped fiber amplifier.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: This thesis describes photodiodes constructed on silicon optical waveguides. The photodiodes are notable for their high-speed performance and simple fabrication methods. Such devices may find use within chip-integrated optical transceivers, which are desired for optical interconnects within large-scale computing systems such as data centers.


title: Analysis and Compensation of Nonlinear Impairments in Fiber-Optic Communication Systems

contributor:
Kumar, Shiva
Electrical and Computer Engineering

abstract:
Fiber optic communications make the backbone of telecommunications. Optical  ber
is an excellent transmission medium due to its low loss, high bandwidth and robustness.
However, the dispersive and nonlinear e ects of an optical  ber lead to signal
distortions. Propagation impairments accumulate over  ber distance and seriously
distort the signal in long-haul communication systems. Transmission performance
can be signi cantly improved by compensating for  ber dispersion and nonlinear effects.
In this thesis, we carry out theoretical analysis of  ber nonlinear e ects and
develop analytical models to characterize di erent kinds of nonlinearities. Moreover,
we investigate various digital and optical methods to compensate for dispersive and
nonlinear distortions, which signi cantly enhance transmission performance, spectral
e ciency and system capacity.

abstract: Thesis

abstract: Candidate in Philosophy


title: OPTIMIZING REGISTERED NURSE ROLES IN THE DELIVERY OF CANCER SURVIVORSHIP CARE WITHIN PRIMARY CARE SETTINGS

contributor:
Bryant-Lukosius, Denise
Nursing

subject:
cancer survivorship care
nursing
primary care

abstract:
Current models of cancer care delivery in Canada are unsustainable due to the rapidly increasing number of cancer survivors at a time when there is a shortage of human and financial resources. With improvements in early detection, diagnosis, and treatment; patients diagnosed with cancer are living longer. There is also growing recognition of the chronic nature of cancer. Provincial cancer agencies have introduced new models of post-treatment follow-up involving early transition of cancer survivors back to their primary care providers. There is limited research evidence about the role nurses working in primary care settings play in the delivery of post-treatment follow-up and cancer survivorship care (CSC). The purpose of this study was to identify and examine, from the perspective of registered nurses, the strengths, barriers, and opportunities for optimizing nursing roles in the delivery of CSC in primary care.
	A qualitative descriptive study was conducted. Participants were recruited through membership lists from the College of Nurses of Ontario and the Canadian Family Practice Nurses Association Ontario and snowball sampling. Purposeful and maximum variation sampling techniques were employed. Participants completed an oral demographic questionnaire and individual semi-structured in-depth telephone interviews. Data collection and data analysis were conducted concurrently.
	The final study sample included 18 primary care registered nurses from 9 of 14 Local Health Integration Networks across Ontario. Overall, participants’ involvement in CSC was quite limited. Registered nurse involvement in CSC was categorized into three relevant themes: care coordination and system navigation; emotional support, and facilitating access to community resources. Barriers and facilitators to optimizing nursing involvement in CSC related to individual participant, practice setting, and primary care team factors. Participants recommended multiple strategies for expanding the role of nurses in CSC.

abstract: Thesis

abstract: Candidate in Philosophy

abstract:
The current approach to cancer survivorship care (CSC) in Canada is unsustainable due to the rapidly increasing number of cancer survivors at a time when there is a shortage of human and financial resources. Patients diagnosed with cancer are living longer and there is growing recognition of the chronic nature of cancer survivorship. Provincial cancer agencies have introduced new models of post-treatment follow-up involving earlier transition of cancer survivors from specialist care back to their primary care providers.
	Currently, there is a gap in research evidence regarding the role nurses working in primary care settings play in the delivery of CSC. This thesis will describe the results of a qualitative descriptive study that identified and examined the strengths, gaps, barriers, and opportunities for optimizing nursing roles in the delivery of CSC within primary care settings from the perspective of registered nurses practicing in primary care.


title: Border Politics: Practices of Zoning, Experiences of Mobility and Life in Displacement. Views From Brazilian Crossroads

contributor:
Nyers, Peter
Political Science

subject:
border politics
South America
displacement
zoning
solidarity
South-South relations
refugees
migration
Brazil

abstract:
This dissertation examines the political negotlations involved in border encounters, focusing particularly on mobile groups in border areas in South America. It discusses the connection between international and border politics, privileging a definition of the latter as the negotiation processes over the terms and modes of presence of the 'inter' of the international. The dissertation analyzes border politics from the perspective of three major tenets: displacement, practices of zoning and the construction of borders as sites of solidarity. I argue that in order to understand these processes we need to elucidate how the global politics of mobility is played out (or translated) in border crossroads and from a range of social groups that encompass not only the Nation-State, but also a myriad of actors that, despite having little or no say in the international framework of human mobility, perform bordering practices that are central to the enactment of difference as a primary trait of inclusion/exclusion from the political. These processes of political differentiation are reinforced but also contested by mobile groups, especially in relation to discourses that try to equate human mobility as a choice between freedom and protection. In important respects, their intervention attempts to problematize the dichotomous portrayal of freedom and protection as two irreconcilable dimensions of life in displacement, thus evincing the possibility that the 'inter' of the international can actually become a site of living, rather than a rite of passage.
I also argue that by incorporating the narratives of diverse social actors at these border crossroads we might come closer to displacing the politics of human mobility from one premised on a conventional reading of the international, as a strategy of separation, modulation and management of difference, towards a global politics of (dis)connections, in which mobile groups can become active participants in the framing of their lives possibilities. This moving-away from the international is always embedded in tenuous, dangerous and ambiguous exchanges about what constitutes mobility, how movement is to be interpreted, stimulated or prevented, where and when it can take place and under what conditions. The dissertation discusses these more theoretical claims in the context of refugee and migration movements in Brazil, particularly in relation to Bolivians, Africans and Colombians living in border zones. As such, this dissertation hopes to contribute to a better understanding of what is at stake in dealing with the border encounter from a political perspective and how different narratives on life in displacement can, in fact, indicate different paths of action and research, especially in the context of South-South circulations.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Discord and Ambiguity Within Youth Crime and Justice Debates

contributor:
Pawluch, Dorothy
Sociology

subject:
youth crime
justice
Canada
culpability of young offenders
severity of youth crime
social context
solution
advocacy

abstract: This dissertation traces debates about youth crime and justice in Canada. On a substantive level, I ask how the social problem of youth crime and justice is constructed, focusing specifically on debates over the culpability of young offenders. I also examine debates over the degree and severity of youth crime and connect the divergent positions on this question to how young offenders are conceptualized. Related to these debates, I examine the search for solutions to youth crime. I argue that positions regarding how to address youth crime are rendered ambiguous given the creation of a hybridized youth justice context which combines various competing goals. On a theoretical level, I explore the relationship between how formulations of "deviant identities" (in this case "young offenders") are related to other areas of advocacy over a social problem. I explore the dynamics of a social problem debate which persists without resolution over an extended period of time. I also address the ways in which social context impacts upon claims made over a social problem.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Reinforcement Schemes for Cold-Formed Steel Joists Having Web Openings

contributor:
Sivakumaran, K.S.
Civil Engineering

subject:
cold formed steel
openings
reinforcement schemes
flexural zones
shear zones
cold formed steel joist

abstract:
The use of cold-formed steel (CFS) structures has become increasingly popular in different fields of building technology. For example, small housing systems using cold-formed steel for wall structures, framing systems and roof structures, including trusses and shielding materials, have been developed during recent years. The reasons behind the growing popularity of these products include their ease of fabrication, high strength/weight ratio and suitability for a wide range of applications. These advantages can result in more cost-effective designs, as compared with hot-rolled steel, especially in short-span applications. It has been common practice in cold-formed steel construction to cut openings in the web of beams for the passage of service ducts and piping. The provision of such openings reduces the story heights and consequently can result in saving of considerable amount of construction materials. On the other hand, the presence of a
large web opening causes localized redistribution of stress around the opening region. The large opening causes loss of strength and changes the buckling characteristics of an entire member. It also affects the flexural stiffness, resulting in poor performance of member under serviceability. It is common practice to reinforce the opening of hot-rolled steel members, but proper reinforcement schemes for CFS perforated members has not been established yet. Various reinforcement schemes for cold-formed steel sections were investigated during this study. Two types of reinforcement schemes (for flexural zones and shear zones) were developed. Fifty-four flexural tests and 33 shear tests were conducted.
Two types of sections (lipped channel joists with h/t ratio 180 and 118) were tested in flexure and one type of section (lipped channel joists with h/t ratio 180) was tested in shear. The study also included a finite element based numerical investigation, consisting of parametric studies on the size (web depth and thickness) of joists, size and shape of web openings, reinforcement and associated fastening schemes. It was observed that a 75 percent of opening in the web of CFS channel joist causes up to 25 percent reduction in flexural strength and up to 60 percent reduction in shear
strength. Such reduced flexural and shear strengths were re-captured by providing proper reinforcement schemes. The flexural reinforcement schemes recommended by the current AISI Standard were found to be ineffective for the sections having low w /t ratios. Bridging channel reinforcement scheme was also considered in this study. Bridging channel reinforcement scheme was capable of restoring the flexural strength of cold formed steel joist having w /t ratios 118 and 180. Similarly, the reinforcement schemes recommended in AISI Standard were not adequate to restore the shear strength of joist sections. A newly developed Virendeel type reinforcement system was capable of restoring the original shear strength of a cold-formed steel joist section.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: The Effect of Flower-Dwelling Ambush Predators on Pollination Systems

contributor:
Dukas, R.
Psychology

subject:
pollinators
flowering plants
fitness
predators
co-evolution
bumblebees
honeybee recruitment dance

abstract: The interaction between pollinators and flowers affects the fitness of both pollinators and flowering plants, which can result in the co-evolution of pollinator and floral traits. Some pollination systems contain flower-dwelling ambush predators that attack visiting pollinators. This interaction could result in co-evolution of predator and pollinator traits as is typical in predator-prey systems. The presence of these predators could also have indirect negative fitness effects on flowering plants by killing or deterring pollinators. This raises the possibility that predator and floral traits also co-evolve. Furthermore, it is possible that this system is best described as a three-species game where predator, pollinator, and floral traits all co-evolve. The ultimate goal of my thesis is to explore this possibility. This is achieved in Chapter 5, which consists of a game theory model of the co-evolution of floral colour with predator and pollinator behavioural strategies. This model is novel, both within the pollination context described here and within a wider context. Furthermore this model is the first to propose that the evolution of floral colour might be affected by the presence of flower-dwelling ambush predators. This is particularly significant given that there has been little discussion about what floral traits might be adaptations to the presence of these predators. A secondary goal of this thesis is to explore how pollinators detect and respond to the presence of flower-dwelling ambush predators as an important subcomponent of predator-pollinator-flower co-evolutionary dynamic. Chapter 2 demonstrates that bumblebees avoid evidence of past predation events, and Chapter 3 demonstrates that the honeybee recruitment dance is affected by exposure to cues of predation risk in a way that should reduce the colony's exposure to predators. Chapter 4 is a model that suggests novel factors that might affect how a population of pollinators distributes itself between predator-free and predator-containing flowers.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: The Role of Support and Sustainability Elements in the Adoption of a Self-management Support System for Chronic Illnesses

contributor:
Archer, Norman P.
Business Administration

subject:
Mobile-Health
Chronic Disease
Self-management
Disease Management

abstract:
The Canadian healthcare system, by design, has been historically oriented to delivering acute and symptom-driven care; however, the current cost of treating chronic disease has risen to an average of nearly 45% of direct costs of the national health budget. As a consequence more attention is being directed to the diagnosis and treatment of chronically ill patients who also may suffer from disabilities, illiteracy, impairment in judgment, depression, or multiple co-morbidities. This has also resulted in a new emphasis on health and disease self-management, to help patients to mitigate and manage the impacts of chronic diseases. This approach affects and involves the patient’s entire circle of care including the patient, healthcare providers, and the patient’s family and friends.
This study discusses how support elements (i.e. decision support, education and training, family and community support) and sustainability elements (i.e. recreation and entertainment, rewards systems, online social networks) combined with online technological support can help to support and provide motivation for chronically ill patients to adopt self-management in a sustainable manner. The PLS (Partial Least Squares) statistical approach was used to validate a proposed SEM (Structural Equation Model) research model with data collected from 198 participants across North America without any prior exposure to our proposed system. The research model hypothesized that support and sustainability constructs have a strong positive influence on the willingness of users to adopt and use the proposed system. The model results in a very good fit for Behavioural Intention to Adopt for patients with no caregiver support (R2=0.71), and for patients with such support (R2=0.65). The results clearly validate our proposed model including a high predictive relevance for endogenous variables. This research provides useful theoretical and practical insights and understanding for design, development and promotion of chronic care self-management systems as well as the perceptions of users regarding the adoption and use of such systems.

abstract: Dissertation

abstract: Doctor of Philosophy (PhD)


title: Enhancement of Superconductivity in Thin Aluminum Films

contributor:
Shewchun, J.
Physics

subject: enhancement, superconductivity, thin aluminum, films, energy,

abstract: The phenomena of energy gap and transition temperature enhancement have been studied on very thin (35-80 A° ) aluminum films, using the technique of electron tunneling through a thin insulating barrier. Transition temperatures as high as 2.16°K have been measured, and the corresponding measured energy gaps are found to be unique. In addition, these thin superconducting films exhibit stable transition temperatures when held in a vacuum. However, upon breaking vacuum, oxide growth occurs, and the tunneling barrier becomes impenetrable. Existing theories proposed to explain the observed enhancements, are discussed in the light of present accumulated experimental evidence. However, it is found that none are capable of explaining adequately the observed enhancements.

abstract: Thesis

abstract: Master of Science (MSc)


title: The Sulphur Nitrogen Bond 1. Lewis Acid Adducts of Tetrasulphur Tetranitride 2. Reaction of Sulphur with dl-α-Methylbenzylamine

contributor:
Olsen, F.P.
Chemistry

subject: sulphur, nitrogen, bond, lewis acid,

abstract: Adducts of aluminum chloride and aluminum bromide with tetrasulphur tetranitride have been prepared and characterized. The reaction of trimethylaluminum and triethylaluminum with tetrasulphur tetranitride has been studied. The reaction of sulphur with α-methylbenzylamine has been investigated, and the reaction mechanism proposed by Sasaki for benzylamine reacting with sulphur has been found to be consistent with the data, provided certain limitations are imposed.

abstract: Thesis

abstract: Master of Science (MSc)


title: Entropies and the Isomorphism Problem for Bernoulli Shifts

contributor:
Behara, M.
Mathematics

subject: entropies, isomorphism, Bernoulli, shifts,

abstract:
 In 1970, D. S. Ornstein introduced some new approximation concepts which enabled him to establish that the Shannon entropy of endomorphism was a complete invariant for a class of transformations known as Bernoulli shifts. This work of Ornstein contains powerful, deep and elegant techniques which have opened up a new period in the theory of measure preserving transformations, or as it is usually called, in ergodic theory.

 This thesis contains the study of two new classes of entropies, the γ-entropy and the δ-entropy, where each of these two classes have Shannon's entropy as a member. The algebraic and analytic properties of these entropies and their characterizations are discussed. Finally, the δ-entropy of endomorphism is defined and it has been used in solving the isomorphism problem for Bernoulli shifts. Thus, it is shown that the isomorphism problem for Bernoulli shifts holds not only for one entropy, but for an infinite class of entropies introduced in this thesis.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: DNA-Dependent RNA Polymerase from an Extremely Halophilic Bacterium

contributor:
Bayley, S.T.
Biology

subject: DNA, Dependent RNA, polymerase, halophilic, bacterium, enzyme,

abstract:
 This thesis describes the isolation and investigation of a DNA-dependent RNA polymerase from the extreme halophile Halobacterium cutirubrum.

 The enzyme system was analyzed under conditions of very high ionic
strengths which are characteristic of the internal salt concentrations
of extreme halophiles and at much lower ionic strengths found in conventional bacterial systems. The enzyme was found to have activity
in a wide range of salt concentrations when attached to its DNA template
in the form of a DNA-Membrane-Protein complex. The enzyme, however, lost the ability to function at high ionic strengths when freed from this complex.

 The properties of the isolated DNA-dependent RNA polymerase from the halophile were then compared to the properties of the same enzyme isolated from the non-halophilic bacterium, Eschericia coli.
Both enzymes were found to have the same approximate molecular weights
and to share the same substrate requirements. The enzymes differed, however, in their response to inhibitors specific for RNA synthesis.

abstract: Thesis

abstract: Master of Science (MSc)


title: PATTERNS OF SPATIOTEMPORAL VARIATION AS TOOLS FOR PREDICTING AND INFERRING ECOSYSTEM DYNAMICS

title: SPATIOTEMPORAL VARIATION IN ECOSYSTEMS

contributor:
Kolasa, Jurek
Biology

subject: Ecology, ecosystem, spatial, temporal, variation, statistics

abstract: Ecosystems and their components (e.g., organisms, physicochemical variables) are dynamic in space and time. This dynamism makes ecological change notoriously difficult to study and manage. This thesis therefore aims to develop new ways of using spatiotemporal information for inference and prediction. Applying theoretical and statistical concepts to patterns of spatiotemporal variation in aquatic ecosystems led to three discoveries that show promise as ecological applications. First, I show that temporal variability of an ecosystem process can be inferred from its spatial variability. This application may be the first quantitative form of the widely-used method, space-for-time substitution. Its use is supported by an analytical framework giving the conditions under which space is a good surrogate for time. Second, I demonstrate the use of spatiotemporal patterns to predict responses of variables when ecosystem fragments are connected. Connection leads to large shifts in spatiotemporal pattern and other response metrics (e.g., temporal variability) for variables showing asynchrony and concentration gradients among sites (e.g., populations). Meanwhile, these changes are minimal if variables exhibit synchrony and homogeneity across space (e.g., energetic variables). A final discovery is that temporal attributes like stability are strong predictors of persistent spatial variation – a pattern that reflects how reliably resource concentrations occur in the same locations. This finding suggests the potential of time-for-space substitution, where one or few well-resolved time series could be used to infer landscape patterns. All but one of the tested approaches were data efficient and broadly-applicable across ecosystems and ecological processes. They thus contribute new possibilities for prediction when data are scarce, as well as new perspectives on dynamics in multi-variable landscapes. Research here shows that work at the intersection of spatial and temporal pattern can strengthen the interpretation of ecosystem dynamics and, more generally, foster synthesis from populations to landscapes.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: The physical and biological components of ecosystems are constantly in flux, varying in value among locations (spatially) and over time (temporally). This dynamism makes it difficult to predict current or future behaviours of ecological variables (e.g., population size). This thesis tests the potential of using spatial and temporal patterns to make inferences and predictions about changes in ecological systems. I tested three new theory-based tools in aquatic ecosystems, finding that: The size of temporal fluctuations in an ecosystem variable can be predicted from the size of value-differences among locations; spatial and temporal patterns can predict how a variable responds when isolated fragments of ecosystems are connected; and attributes of ecosystem variables (e.g., their stability) can indicate the likelihood of resources recurring in the same location. Findings show that new insight into spatial and temporal patterns can help prediction and management in complex landscapes.


title: Linear Programming Based Resource Management for Heterogeneous Computing Systems

contributor:
Down, Douglas G.
Software Engineering

subject:
distributed heterogenous computing
resource management system
linear programming problem
Desktop Grids
cluster computer system
performance

abstract:
An emerging trend in computing is to use distributed heterogeneous computing (HC) systems to execute a set of tasks. Cluster computer systems, grids, and Desktop Grids are three popular kinds of HC systems. An important component of an HC system is its resource management system (RMS). The main responsibility of an RMS  is assigning resources to tasks in order to satisfy certain performance requirements. For cluster computer systems, we propose a new mapping heuristic which requires less state information than current heuristics. For Desktop Grids, we propose a new scheduling policy that exploits knowledge of the effective computing power delivered by the machines and the distribution of their fault times in order to improve performance. Finally, for grids, we propose a new decentralized load balancing policy which dramatically cuts down the communication overhead incurred in state information update. The proposed resource management policies utilize the solution to a linear programming problem (LP) which maximizes the system capacity. Our simulation experiments show that these policies perform very competitively, especially in highly
heterogeneous systems.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Long-Term Potentiation and Long-Term Depression in the Corticostriatal Motor System of the Non-Anesthetized Rat

contributor:
Racine, R. J.
Psychology

subject:
long term potentiation
long term depression
learning and memory
neural plasticity
basal ganglia motor loop
corticostriatal pathway
thalamocortical

abstract:
Long-term potentiation (LTP) and depression (LTD) are activity dependent long-lasting changes in synaptic efficacy and have been proposed as mechanisms for learning and memory. Although the exact relationship of LTP and LTD to memory is not known, they do share some properties and mechanisms that relate to memory, such as the strengthening and weakening of synapses. LTP and LTD have been studied extensively in hippocampal brain-slice preparations, due to its relatively organized structure, ease of induction, and its critical function in memory storage. Less work has been done in the neocortex despite the belief that it is heavily involved in the storage of long-term memories. Activity dependent plasticity has also been demonstrated in the basal ganglia in vivo and in vitro, but the results have been somewhat inconsistent. The experiments
presented in this thesis explore a novel form of neural plasticity in two excitatory pathways (corticostriatal and thalamocortical) of the basal ganglia motor loop in the intact brain in awake, freely behaving rats. In thalamocortical slice preparations, simultaneous presynaptic stimulation and postsynaptic depolarization can induce L TP in animals prior to the critical period. However the results presented in this thesis show that applied stimulation to the thalamocortical pathway failed to produce either LTP or LTD in the awake freely moving animal.Corticostriatal LTD has been shown in slice preparations following direct tetanic stimulation of the striatum. In the current experiment, cortical stimulation failed to induce LTD although there was an observable decrease in the evoked potential following low-frequency stimulation.
Corticostriatal L TP has been shown to depend on the type of stimulation applied. High-frequency and theta burst stimulation produced long-lasting changes in response amplitude in the corticostriatal pathway, with theta burst stimulation appearing to be the more effective stimulation protocol for inducing LTP in both the early and late components. Paired stimulation of the substantia nigra pars compacta and cortex indicated a modulatory action of dopamine on corticostriatal synaptic plasticity. Pairing led to a stable increase in the amplitude of LTP of both early and late components. We also report that a temporal relationship exists in the striatum with respect to the release of nigral dopamine and cortical glutamate. Simultaneous
stimulation produced a more robust L TP compared to the two other conditions in which there was an applied stimulation delay to either the corticostriatal or nigrostriatal pathway. The results demonstrate the mechanistic differences, not only between the thalamocortical and corticostriatal pathways, but also slice and anesthetized preparations. The results also emphasize the need for further study on mechanisms of L TP and LTD in the various excitatory and inhibitory pathways of
the basal ganglia motor loop.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: A Numerical Investigation of Natural Convection in Porous Media

subject: numerical, convection, natural, porous media, heat, temperature

abstract: Error of labeling pages or Page 102 Not included in thesis.

abstract:
 A semi-explicit scheme for the solution of transient multdimensional
natural convection is made to study natural convection
in porous media. The conservation equations are phrased in primitive
form. Heat tranfer between the solid and liquid phases is modelled
by representing the porous medium as an assemblage of spherical
particles, and solving the conduction problem for such a system at
every time step. Nusselt numbers were calculated from the temperature
and velocity profiles. Numerical results for heat transfer through
fluid saturated porous media heated from below are in good agreement
with published experiments.

abstract: Thesis

abstract: Master of Engineering (MEngr)


title: Impurities and the Evaporation Morphology of Zinc Single Crystals

contributor:
Ives, M.B.
Physics

subject: optical and scanning electron microscope

subject: evaporation morphology

subject: zinc single crystals

subject: bulk impurities

subject: gaseous

abstract:
 In this thesis the results of optical and scanning electron
microscopic investigations of the evaporation morphology of zinc single crystals are presented. Dislocation etch pits developed on (0001) zinc cleavage surfaces. A mechanism is proposed to account for enhanced evaporation at decorated dislocations. The observation of macroledges on pit faces is reported and attributed to impurity-induced bunching of monatomic ledges, the impurities having out-diffused from the bulk. A proposed model for evaporation of faceted surfaces is used to interpret the ledge morphology which developed when samples were evaporated in an oxygen environment. Finally, a correlation between the effects of bulk impurities and gaseous impurities on ledge morphology is demonstrated.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: On Sequential Binomial Estimation

contributor:
Chorneyko, I.Z.
Mathematics and Statistics

subject: sequential, binomial, estimation, sampling

abstract: This thesis is concerned with the properties of sequential binomial estimation. It illustrates the construction of optimal sequential binomial sampling plans for point estimation problems in which, according to custom, each loss function is taken to be a constant times the square of the error. The way such a constant affects the sizes of the constructed sampling plans is also within the scope of this thesis.

abstract: Thesis

abstract: Master of Science (MSc)


title: Wet Adhesion of Polyvinylamine-Phenylboronic Acid to Cellulose Hydrogel

contributor:
Pelton, Robert H.
Chemical Engineering

subject: wet adhesion, acid, cellulose, hydrogel, boronic, polymers

abstract:
 The ability of a never-dried paper web on a paper machine to resist breakage is commonly referred to as paper wet-web strength. Low wet-web strength can lead to frequent breaks which interrupt production and lower paper machine efficiency. Currently, no commercial products provide the function of enhancing wet-web strength. Boronic acid derivatized polyvinylamine (PVAm-PBA) showed high instantaneous wet adhesion to regenerated cellulose membranes. The objective of the research summarized in this thesis was to determine the factors and mechanisms dictating PVAm-PBA adhesion to wet cellulose. In addition, narrowly distributed PVAm microgel was prepared and the wet adhesion of boronate-microgels to cellulose is reported.

 The phase behavior and surface tension of PVAm-PBA were measured as functions of pH and the degree of PBA substitution. The pH ranges over which phase separation occurred increased with PBA substitution. 150 kDa PVAm-PBA with 4% derivatization phased separated at pH 8.5 to 9.5.The copolymer based on 51 % substitution was insoluble over most of the pH range. The hydrophobicity of copolymers was reflected in the significant lowering of surface tension particularly at high pH. Additionally, fructose, which binds to borate, influenced the titration curves but did not influence surface tension.

 Pairs of wet, regenerated cellulose films were laminated with PVAm-PBA and the forces required to delaminate the never-dried laminates, were measured as functions of adhesive structure and application conditions. The greatest wet adhesion was obtained with 150 kDa PVAm with 16% of the amines bearing phenylboronic moieties. The pH at which the PVAm-PBA was adsorbed onto the cellulose was the dominant process parameter. The specific role of the phenyl boronic groups was illustrated in two ways: a) replacing the B(OH)2 with OH (i.e. phenol) gave much lower adhesion; and, b) wet adhesion was greatly reduced by the presence of sorbitol which effectively competes with cellulose for boronate binding sites.

 The interaction of boronate and cellulose was studied. Owing to poor solubility of cellulose, two model polymers: dextran and hydroxyethyl cellulose (HEC) and two saccharides: glucose and cellobiose were measured by boron NMR measurement, tensile extension, fluorescence spectra, viscometer and peeling test methods. In conclusion, carbon-1, 2 diols at one end of cellulose chain can react with boronic acid. By contrast, carbon-2, 3 diols, which are abundant on cellulose chains, cannot react with boronic acid and the other diols, such as carbon-3, 4 diols and carbon-4, 6 diols cannot react with boronic acid. The high adhesion of boronate containing polymers to cellulose membranes was attributed to boronate ester formation with the cellulose end groups on the membrane surfaces.

 Finally, a simple and effective methodology was demonstrated for the preparation of polyvinylamine microgel with a narrow distribution. Boronate derivatives of PVAm microgels displayed very high wet adhesion to cellulose over a broad pH range.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)