title: The Energetics of Transitibal and Transfemoral Amputees Walking on Titanium and Stainless Steel Prostheses

contributor:
Dowling, James
Biomechanics

subject:
energetics
transtibial amputee
transfemoral amputee
titanium prostheses
stainless steel prostheses
prostheses

abstract: Several studies have been devoted to the metabolic costs of amputees walking on prostheses with different masses added to their components. However, limited study has been directed at quantifying the mass differences of the actual materials available to amputees and the metabolic and mechanical work required to walk on these materials. The energetics of two materials currently used in the design of lower extremity prosthetics were examined in an attempt to determine if mass differences had an effect on amputee walking. A total of fifteen, unilateral amputees (8 transfemoral and 7 transtibial) performed treadmill walking on prostheses assembled from titanium and stainless steel components. Standardized components (knees, pylons, adapters, feet) made from each material were added below the level of the socket. Submaximal oxygen consumption {W/kg} and mechanical power allowing transfers within and between segments {W/kg} were calculated as subjects walked at self-selected velocities until steady state was achieved. Results show that despite significant mechanical differences [F(1,12)= 4.85, p<.048], the decreased mass associated with the use of titanium materials does not have an effect on the metabolic costs [F(1,14)=1.45, p<.249] of the subjects in this study. In addition, stride rate and stride length showed little differences when walking with both materials. Further division of subjects by age and experience walking on a prosthesis do suggest that older amputees and established walkers do benefit most from the use of titanium, both metabolically and mechanically. The choice of materials for use in every day walking will display differences in the mechanical work of amputees however, these differences are not great enough to realize metabolic consequences.

abstract: Thesis

abstract: Master of Science (MS)


title: Mating System and Mitochondrial Inheritance in a Basidiomycete Yeast, Cryptococcus neoformans

contributor:
Xu, Dr. Jianping
Biology

subject:
cryptococcus neoformans
mating system
mitochondrial inheritance
basidiomycete yeast

abstract: In the majority of sexual eukaryotes, mitochondria are inherited predominantly from a single, usually the female, parent Like the majority of higher plants and animals, the pathogenic yeast Cryptococcus neoformans has two mating types (sexes), however, these two sexes are morphologically similar. In this study, I examined the distribution of the mating types and how mating types influence the inheritance of mitochondria in C. neoformans. My survey of mating type alleles in 358 isolates collected from four geographic areas in the US showed a biased distribution of mating type alleles with most isolates containing mating type a alleles. To characterize the role of mating type locus on mitochondrial inheritance, I constructed two pairs of congenic strains that differed only at the mitochondrial genome and mating type locus. Mating between these two pairs of strains demonstrated that uniparental inheritance in C. neoformans was controlled by the mating type locus and progeny predominantly inherited mitochondria from the mating type a parent. Specifically, we identified two genes within the mating type locus, SXIIa in mating type a strain and SXI2a in mating type a strain, that control mitochondrial inheritance. Disruption of these two genes resulted in biparental mitochondrial inheritance in sexual crosses. These two genes are the first ones identified capable of controlling uniparental mitochondrial inheritance in any organism. In addition, we determined that the deletion of the SXIIa gene enhanced the spread of mitochondrial introns in sexual crosses. This discovery is consistent with the hypothesis that uniparental lnheritance might have evolved to prevent the spread of selfish cytoplasmic elements.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Determination of Tissue Optical Properties from Interstitial Fluence Rate Measurements: A Study of the Systematic Errors

contributor:
Patterson, M. S.
Physics

subject:
tissue optical properties
interstitial fluence rate measurement
fluence
systematic error
optical property
interstitial fluence rate

abstract:
Increased efficacy of light and laser applications in medicine is achieved by accurate light dosimetry. A minimally invasive technique for the determination of the optical coefficients of tissue involves interstitial measurements of the local fluence rate at two or more points in the tissue using isotropic, fibre optic detectors and application of a diffusion model of light propagation. The diffusion models assume simple, homogeneous tissue geometries, possibly oversimplifying the effect of tissue heterogeneities and boundaries. The primary goals of this study were to investigate the influence of realistic finite geometries on the fluence rate distribution and to quantify the systematic errors in the derived optical properties.
A Monte Carlo model was developed to predict the fluence rate distribution in any plane of interest in a medium and was verified by comparison with diffusion theory solutions for simple geometries. Fluence rate measurements were made in optically infinite and semi-infinite phantoms for a wide range of optical properties and it was determined that the optical coefficients were derived accurately for phantoms with ueff> 0.2 mm-1 and 2 < ut'<10 mm-1. Measurements were also made in finite spherical volumes with absorbing (Rd = 0.35) and diffuse reflecting (Rd =0.85) boundaries for three optical phantoms and comparisons of the experimental fluence rates with the predictions of the finite volume Monte Carlo model are presented. Boundary effects were observed to be significant within 4 transport mean free paths (mfp') of the boundary. The optical coefficients were derived by applying a diffusion solution for an infinite medium and it was determined that within 2 mfp' of the boundary, the derived ua was overestimated by 40% and underestimated by 20% for the absorbing and reflecting boundaries, respectively.

abstract: Thesis

abstract: Master of Science (MS)


title: The Tritone Paradox: An Experimental and Statistical Analysis

title: The Tritone Paradox: A Statistical Analysis

contributor:
Platt, John
Psychology

subject:
tritone paradox
experimental
statistical analysis

abstract:
When tones comprised of six octave-related harmonics are placed in pairs, where the two tones are separated by a tritone, some subjects perceive the direction of pitch change from the first to the second tone as ascending, while other subjects perceive it as descending. This is the basis for what is currently labeled the Tritone Paradox. The Tritone Paradox was investigated in a set of four experiments that made use of different experimental procedures that employed a 0-750 ms silent interval between tones in a trial-pair, different methods of stimulus presentation (i.e. open air or earphone) and 125 - 500 ms stimulus durations. Major emphasis was placed on the implementation of a standardized experimental procedure and the use of a standardized method of analyzing results in a Tritone Paradox experiment. To this end, an analysis method was designed using circular statistics, which resulted in a truly objective method of analyzing and classifying subjects while making use of all subject data. Analyses indicated that peak-pitch class was highly correlated with the angle of a mean vector (AMV) and that the depth of a profile was correlated with the length of a mean vector (LMV). The AMV and LMV may be combined to produce a single summary measure for a subject's performance. Two modes of responding employed by subjects were identified. Profiles generated using a spectral-envelope-controlled mode of responding are characterized by judgments of tones under one envelope being close to 180° out of phase with judgments made under a spectral envelope centered one half octave away from the other. Profiles generated using a pitch-class-controlled mode of responding are
characterized by judgments of tones under one spectral envelope closely resembling judgments of tones made under a spectral envelope centered a tritone away from the first spectral envelope. Angular-Separation analysis details the difference between the AMV for two separate profiles generated by a subject. This analysis technique is a fast, reliable method for identifying individual differences in mode of responding between subjects. Angular-Separation analyses were used to verify the presence of 'spectral-envelope-controlled' subjects, which were first described in detail by Repp (1994). These subjects appeared in significant proportions in all conditions. Based on the results of these analyses, the traditional practice of using a single-averaged profile to describe a subject has been questioned. Such a profile does not adequately describe the performance of a subject using a spectral-envelope-controlled mode of responding. The single-averaged profile masks the differences between these subjects and those using a 'pitch-class-controlled' mode of responding, which are the subjects typically described in the literature. Results of the Angular-Separation analysis across Experiments 1 -4 showed similar proportions of subjects using a pitch-class-controlled or a spectral-envelope-controlled mode of responding. Evidence was found to indicate that the largest proportion of subjects using a pitch-class-controlled mode of responding was observed in an experimental condition that used 125-ms stimuli with no silent interval between tones in a pair. Evidence was also found to indicate that the largest proportion of subjects using a spectral-envelope-controlled mode of responding was observed in an experimental condition that employed 500 ms stimuli with a 500 ms silent interval between tones in a trial pair. It therefore appears that the duration of tones and the
duration of a silent interval between tones in a trial pair will influence the mode of responding adopted by a subject in a Tritone Paradox experiment. The pure-tone pre-test, described in the literature as a subject selection tool, was investigated and results indicate that performance on such a pre-test does not predict how consistent a subject's performance will be in a Tritone Paradox task. Although mean LMV decreased as pre-test error scores increased, there was no significant correlation found between individual subjects' error scores and LMV values. This pretest, however, has some value in predicting some subjects' mode of responding. The vast majority of subjects with three or more errors on a pure-tone pre-test produced profiles that were classified as spectral-envelope controlled. These results suggest that the bulk of those subjects eliminated in past Tritone Paradox experiments that employed a pure-tone pre-test, may have been subjects who were far more likely to use a spectral-envelope controlled mode of responding.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Modulation of RPOS Expression by an Inducible RPOS Sense and Antisense on a High-Copy Plasmid and as a Single Copy in the Escherichia Coli Chromosome

contributor:
Schellhorn, H. E.
Biology

subject:
escherichia coli
chromosome
rpos sense and antisense
rpos expression
high-copy plasmid

abstract: Escherichia coli and several other bacteria express a stationary phase sigma factor, RpoS, for RNA polymerase that is responsible for inducing the expression of stress response genes. rpoS expression is induced during early exponential phase and the concentration of RpoS dramatically increases during the transition from log phase to stationary phase. The goal of this study was to test whether rpoS expression could be modulated using an inducible rpoS antisense and rpoS sense. In the first part of this study, a rpoS antisense under the control of an IPTG-inducible promoter was tested for its efficiency for modulating the expression of the RpoS regulon. RpoS-dependent and RpoS-independent lacZ fusions were utilized to quantify the effect of rpoS antisense expression on rpoS translation. Unlike an earlier study, the results of this study suggest that the rpoS antisense was not induced and/or that it was not inhibiting the expression of RpoS-dependent genes. In the second part of this study, an IPTG-inducible rpoS sense was used to test whether expression of certain members of the RpoS regulon were solely dependent on RpoS and not additional factors present in stationary phase. Thus, their expression could be induced in exponential phase. The rpoS sense was integrated into the E. coli chromosome at the ebg locus by homologous recombination utilizing a one-step PCR method. Some putative rpoS sense recombinants showed an increase in catalase expression, which is known to be RpoS-dependent. However, upon further verification, the 5kb PCR fragment encoding the inducible rpoS sense did not appear to have integrated to the intended site.

abstract: Thesis

abstract: Master of Science (MS)


title: Toxicology of Organic Cations and Regulation of Organic Cation Transport in Drosophila melanogaster

contributor:
O' Donnell, Dr. Michael J.
Biology

subject:
toxicology
organic cation transport
drosophila melanogaster

abstract:
Insects accumulate various xenobiotics and toxic molecules through feeding and environmental exposure. This study examines the toxicology and regulation of a class of toxic molecules, organic cations, in Drosophila melanogaster. The results of this thesis demonstrate that transepithelial tetraethylammonium (TEA) secretion across the main segment of the Malpighian tubules is increased in response to diuretic factors. Both cAMP and cGMP, which increase transepithelial potential (TEP), as well as tyramine and LK-1, which decrease TEP, all enhanced TEA secretion. Both inc~eases and decreases ofTEP may enhance proton transport into the lumen of the tubule thus increasing the rate of organic cation/proton exchange across the apical membrane. These findings suggest that factors previously referred to as diuretic factors may in fact :let primarily or secondarily as stimulants of organic cation excretion.
Haemolymrh concentrations of TEA increased linearly with the concentration of TEA in the diet and declined rapidly upon transfer of the larvae to TEA-free diet. The rate of decline was reduced by slowing the metabolic rate or by the addition of cimetidine to a diet containing TEA. Although larvae tolerated high levels of TEA in the diet, mortality increased when TEA was combined with either quinidine or cimetidine. It is suggested that inhibition of TEA transport by cimetidine or quinidine results in prolonged exposure to higher levels of TEA in the haemolymph and a consequent increase in toxicity. Surprisingly, TEA flux and fluid secretion rate were both reduced in Malpighian tubules isolated from adult flies raised on TEA-enriched diet. This suggests that the high concentration of TEA in the diet produced a non-lethal yet deleterious effect on the Malpighian tubules of Drosophila.

abstract: Thesis

abstract: Master of Science (MS)


title: The Role of Early Region I Functions During Biochemical Transformation of Rat Cells by Human Adenovirus Type 5

title: Role of AD5 Early Region I Functions During Transformation of Rat Cells

contributor:
Graham, F. L.
Biology

subject:
rat cell
AD5 region
transformation of rat cell
human adenovirus type 5

abstract: The purpose of this study was to assess the effect of early region 1 functions of Ad5 on the ability of viruses containing a selectable marker in early region 3 (E3) to transform mammalian cells. To do this I have constructed and characterized five recombinant viruses containing the thymidine kinase (tk) gene from Herpes Simplex Virus type 1 (HSV1) inserted in E3. The biochemical transformation assay performed using these recombinant viruses allowed the separation of the selection process (incorporation and expression of tk) from the requirement for expression of E1 functions. The method of isolating the desired recombinant viruses was in vivo recombination following mixed infection of 293 cells. The parental viruses used were: hr 1 which expresses a truncated version of the E1a 243R product lacking amino acids 166 to 2437 pm975 which fails to express the E1a 289R product d1312 from which the majority of the E1a coding region has been deleted: hr6 which fails to express a wild type E1b 496R protein; and wild type Ad 5. Each coinfection was done with d1E1,3tk, a previously constructed recombinant virus (Haj-Ahmad and Graham, 1986). Using the resulting recombinant viruses, semipermissive tk- Rat 2 cells were infected and selected for conversion to the tk+ phenotype, as well as being assayed for viability post infection. Comparisons were made of tk transformation frequencies with and without correction for differential cell viability measured after infection with different viruses. Correction for differential cell viability greatly reduced the differences in transformation frequencies observed directly. However hr1tk remained able to induce tk+ transformation at a significantly greater frequency than hr6tk, pm975tk, or Ad5tk. The mutants d131,2tk and d1E1,3tk gave statistically indistinguishable results corresponding to an intermediate level of transformation, while hr6tk, pm975tk, and Ad5tk were grouped together as being least efficient at transformation. The infected Rat2 cell viability assays provide evidence of a correlation involving expression of the early region la (Ela) 289 residue product, efficient viral DNA replication, and cell death. Recombination frequencies obtained during the isolation of the recombinant viruses varied greatly depending on the combination of infecting parental viruses. The following factors appeared to affect recombination frequency: 1. the input ratio of the coinfecting viruses; 2. interference in the replication of d1E1,3tk relative to the other virus present; and 3. the presence of small numbers of mismatched base pairs (seven) near the left terminus of some of the viruses used in coinfection with d1E1,3tk.

abstract: Thesis

abstract: Master of Science (MS)


title: Social Influences on Mate Choice in Japanese Quail, Coturnix japonica

title: Social Influences on Mate Choice

contributor:
Galef, B.G.
Psychology

subject:
social influences
mate choice
japanese quail
coturnix japonica

abstract:
Classical theories of how animals make mate choices have focused on each sex's
inherited preferences for the other sex's traits or behaviours. The present thesis
was undertaken to investigate how social factors play a role in determining an
animal's choice of mate. In the series of experiments reported here, 'focal' female
and male Japanese quail were given the opportunity to observe another quail (a
'model') of the same sex mating with a conspecific of the opposite sex (a
'target'). Results of experiments described in chapters 2 and 3 revealed that focal
females: (1) displayed an increased tendency to affiliate with male targets that
they had observed mating with model females, and (2) found a target male more
attractive if he had been observed just standing near another female. In Chapter 4,
social influences or male mate choice were investigated. Focal males: (1)
exhibited a decrease in their preference for female targets that they had observed
mating with model males, and (2) showed a decrease in preference for a female
target only if she had been seen mating with or being courted by a model male,
not simply standing near him. Finally, in chapter 5, it was determined that for
quail of both sexes, affiliation time was a reliable predictor of focal subjects'
actual choice of a mate. Taken together, these results are consistent with the
hypothesis that females gain benefits from attending to the mate choices of other
females, whereas for males there is a cost associated with mating with a female
that had recently muted with another male.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Disinhibition of an Operant Response

contributor:
Kamin, L.J.
Psychology

subject: operant, operant response, disinhibition, disinhibition of an operant response

abstract:
A total of 320 rats were employed in experiments analyzing the phenomenon of disinhibition of an operant bar-pressing response. The parameters explored were type of "inhibitory operation" preceding the test for disinhibition, and modality, duration, directionality, intensity, and prior exposure to the disinhibiting stimulus. The disinhibition phenomenon was highly general, occurring under almost all test conditions. The phenomenon, however, could be produced during extinction only when probability of response was at a "critical" low, but greater than zero, level. When animals with the same "critical" response probability were tested during acquisition, before bar-pressing had reached a higher level of probability,
disinhibition never occurred. Theories attempting to account for both the inhibiting and disinhibiting effects of extraneous stimuli were examined.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Rating Cadence Stability: The Effects of Chord Structure, Tonal Context and Musical Training

title: Rating Cadence Stability

contributor:
Platt, J. R.
Racine, R.
Psychology

subject:
cadence
cadence stability
musical training
music theory
tonal context
chord structure

abstract:
Cadences are orderly progressions of chords which occur in classical and contemporary Western music. They can
serve as anchoring points for the perception of musical key and of tonality. The rules governing the structure and usage of cadences have been set forth in music theory. In a series of experiments, listeners were able to rate the stability of simple two-chord cadences without explicit knowledge of music theoretical concepts. The stability ratings obtained for the cadences presented in these experiments were affected by the listener's musical training (inexperienced or formally trained), by the cadence type (chord progression moving toward or away from the tonic), by the position of the root (in the lowest or uppermost note position of chord) by the direction of cadence resolution (upward or downward pitch change). and by the tonal context. The tonal context was an ascending or descending diatonic scale in the key of G-major or C-major played before each cadence trial. Two hypothetical listening strategies were introduced as possible ways of perceiving musical cadences. Melody-tracking was defined as a simple analytic listening strategy which focused on the soprano voice of each chord in a cadence. Voice-tracking was defined as a flexible strategy which allowed the listener to focus on either the soprano or the bass voice in the triad sequence. Musically trained listeners' ratings generally conformed to the voice-tracking strategy. Their ratings followed conventional standards consistently and accurately. They rated G-C cadences most stable in a C-major context. and C-G cadences most stable in a G-major context. Untrained listeners' ratings did not consistently show this effect of key context. Their ratings generally conformed to the melody-tracking strategy. They considered downward resolution of a cadence more stable than upward resolution, and they gave higher stability ratings to cadences when the soprano voice instead of the bass voice led the cadence. All listeners tended to rate plagal cadences as more stable than imperfect cadences, and perfect cadences as more stable than other cadences. They also generally gave higher stability ratings to soprano-led cadences than to bass-led cadences. The musically untrained listeners were able to assign meaningful stability ratings to cadences. despite their lack of musical terms. The trained listeners appeared to approach the task in a different way. Over the course of formal musical training. trained listeners may have learned to use a more flexible strategy while maintaining a high level of accuracy and consistency in their task performance.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: The Infrared Absorption Spectrum of Portlandite [Ca(OH)2]

contributor:
Petch, H. E.
Physics

subject:
portlandite
infrared
absorption spectrum

abstract: The Infrared absorption of a single crystal of portlandite, over a temperature range from room temperature to below the melting point of hydrogen, was studied with both polarized and unpolarized radiation. The apparatus and experimental techniques are described, and the results and their significance in relation to earlier experimental work on the crystal structure of portlandite are discussed.

abstract: Thesis

abstract: Master of Science (MS)


title: Factors Affecting Bone Development in Adolescent Females

contributor:
Blimkie, Cameron J.R.
Human Biodynamics

subject:
bone development
adolescent females

abstract:
Thesis
Master of Science (MS)


title: "To Suffer and To Serve": British Military Dependents, Patriotism and Gender in the Great War

contributor:
Rempel, Dr. R.A.
History

subject:
british military dependents
gender
great war

abstract: During the Great War, the dependents of all servicemen in each branch of the British Armed Forces became theoretically eligible for maintenance at public expense. In August 1914, only a fraction of all Army wives and no Navy wives were eligible for allowances or pensions; by November of that year all were entitled to some level of assistance. The organisational chaos caused by the Liberal Government's decision to grant "universal" benefits to dependents sparked an extensive press campaign and inspired the formation or expansion of a large number of charitable agencies. 1915 and 1916 witnessed attempts on the part of the Asquith Liberal Government and the Asquith Coalition Government to respond to these expressions of concern with a series of half measures. By the summer of 1916, however, the issue had been complicated by the looming problems of reconstruction and predictions of the collapse of the system under the demands of millions of demobilised servicemen. Before the resignation of Asquith in December 1916, the Ministry of Pensions Act was passed. Thus, between August of 1914 and December of 1916 the system had been completely transformed from a disparate, and limited trickle of maintenance for a select few to a widely dispersed benefit controlled by the state. The accelerated pace of social policy in this arena has attracted some attention particularly from feminist historians who describe this system as the cornerstone of the gendered British welfare state. In illuminating some important issues in the debate over these benefits, this approach has obscured others. While it is crucial to understand the roots of inequity in the British welfare state, too narrow a focus has tended to obscure continuity in practice and theory and minimise the impact of contemporary attitudes on the development of these policies. This thesis counteracts the tendency of feminist historians to apply presentist models by demonstrating that charities and governmental agencies responsible for the welfare of servicemen's dependents owed as much or more to traditional Liberal, Conservative and patriotic conceptions of poor relief as to New Liberal ideals of state responsibility. As well, by focusing on the process of decision making at the highest levels of government, this thesis demonstrates the heterogeneity of people and ideals influencing the formation of policy in this period. Both pragmatic and theoretical concerns inspired the drive for reform in this arena. During the Great War, the traditional role of women as the first victims of any war had been partially superseded by the necessity to convince them of their centrality to the war effort. Some perceived the moral and physical power wielded by women in wartime as a promise, others as a threat; both sides of the debate used the treatment of servicemen's wives and widows as a bulwark for their arguments. Servicemen's wives and widows fit neatly into the dichotomy of the female role in wartime; their image could be used to promote an idealised form of passive female bravery and to counteract the "masculinising" tendencies of the war. The ubiquity of such images contributed to the conception of these women as inherently "deserving" of public maintenance. Through the examination of such images, this thesis demonstrates the link between the vagaries of public opinion and the often haphazard formation of social policy.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: The Ratio of the Scalar and Tensor Coupling Constants in Beta-Decay

title: The Ratio of the Coupling Constants in Beta-Decay

contributor:
Preston, M.A.
Physics

subject:
scalar coupling
tensor coupling
coupling constant
ratio
beta decay

abstract: The beta-decay interaction contains two terms which consist of invariant products of two scalars and two tensors respectively. The relative absolute magnitude of these two terms is fairly well established but there has been some controversy over their relative sign. In this thesis the form of the interaction is investigated by means of an analysis of the second-forbidden decay spectrum of Cs137 and it is concluded that the relative sign of the scalar and tensor terms is negative.

abstract: Thesis

abstract: Master of Science (MS)


title: Fission Yields of Cesium, Rubidium, and Strontium Isotopes and Their Relation to Fine Structure in Fission

contributor:
Thode, H. G.
Chemistry

subject: fission cesium rubidium strontium isotope

abstract:
The various concepts of the fission process, mass and charge distribution, and fine structure in fission yields are reviewed. Details and results of mass spectrometric analyses of fission-product samples of cesium, rubidium, and strontium are reported. Absolute yield values have been assigned to the mass 87, 135, and 137 chains. Relative yields of the mass 88 and 90 chains have been determined. A mechanism is postulated to account tor anomalies in fission fine structure. The
Glendenin mechanism of instantaneous neutron emission is found to require
modification.

abstract: Thesis

abstract: Master of Science (MS)


title: Exploring the impact and roles strategic government leadership plays in adoption and use of eHealth in low resource countries: a case study of the medical and dental council of Nigeria as a professional health regulatory agency

contributor:
Archer, Norm
eHealth

subject: eHealth, healthcare regulation, low resource countries, policy, strategic leadership, governance, stewardship, implementation adoption, professional health regulation

abstract:
“Exploring the Impact and Roles that Strategic Government Leadership Plays in the Adoption and Use of eHealth in Low Resource Countries: A Quantitative and Descriptive Study of the Medical and Dental Council of Nigeria as a Health Regulatory Agency”.

MSc eHealth Defense Candidate: Victor Gbenro

Governments of low resource countries (LRCs) have embraced and leveraged the potential benefits Information Computer Technology (ICT) brings to the healthcare sector, taking various steps to adopt and use eHealth to improve healthcare delivery despite recognized challenges. LRCs have been identified as most challenged with the implementation of policies that can drive the development of critical sectors. Despite the development of policies and frameworks in these countries, many still struggle to deliver on their health goals. It is yet to be fully understood to what extent professional health regulatory agencies (PHRAs) understand their roles in effective regulation, as it would relate to medical education, professional conduct and registration of practitioners. The Healthcare workforce is one of the core building blocks of any health system and the regulation of the workforce is central to the provision of quality healthcare services. PHRAs provide strategic leadership through existing legislation, policies, and frameworks and are themselves adopting the use of ICT in a range of applications.  These include the registration and licensure process of practitioners, and training and retraining of practitioners through continuing professional development activities. In 2016, the Nigerian government approved the implementation of it National ICT Strategic Framework for health and empowered its agency, the National Information Technology Development Agency (NITDA) which is an agency in the ministry of communication to provide the required leadership, governance, and stewardship in coordinating and improve upon the use of ICT in all key sectors of the country. This study was undertaken to understand the role PHRAs like the Medical and Dental Council of Nigeria (MDCN) a regulatory body for the professions of medicine and dentistry in Nigeria provides Strategic Government Leadership (SGL) in the adoption and use of eHealth tools through policies and legislation in the health sector. The study also assessed the knowledge and perception of employees of the (MDCN) on existing eHealth policies and legislation and of their relevancy or adequacies in providing effective regulation. The study answers the research questions i) does a relationship exist between SGL and capacity for eHealth innovation and technological/ infrastructural development? ii) What are the measures taken and the importance of the security and privacy of practitioner records to PHRA? and iii) Does SGL, as demonstrated through policy development, affect the adoption and use of eHealth by employees of the PHRA? A systematic literature review was performed, and a structured questionnaire was administered to MDCN professional staff. The results were subjected to statistical analysis to investigate relationships between the dependent variable (SGL) and 14 independent variables representing the 15 constructs from the questionnaire. A regression model found four significant predictors of the value of the dependent variable. A study of other related PHRAs is recommended to improve the suitability of the framework proposed, considering the limitations of this study.

abstract: Thesis

abstract: Master of Science (MSc)


title: Electrically actuated microfluidic methods of sample preparation for isothermal amplification assays

contributor:
Selvaganapathy, Ponnambalam (Ravi)
Mechanical Engineering

subject:
Point-of-care
DNA amplification
Droplet based system
microfluidics integrated devices
Microfluidics systems for LAMP
Microfluidics for LAMP

abstract:
Waterborne or foodborne diseases are caused by consuming contaminated fluids or foods. The presence of pathogenic microorganisms can contaminate food or drinking water. These microorganisms can cause sickness even if they are present in minimal concentrations. The World Health Organization (WHO) has defined the standards for clean drinking water as the absence of E. coli in a 100 mL collected volume. Contaminated water or food can cause many diseases, and diarrhea is one of a prominent disease. Early detection of contamination in food or drinking water is critical. Conventional culture-based methods are time-consuming, labour intensive, and not suitable for on-site testing. Nucleic acid-based tests are sensitive and can rapidly detect pathogens. Microfluidic technology can play a significant role to develop low-cost, rapid, integrated, and portable nucleic acid-based detection devices. Microfluidic systems for isothermal amplification assays can be classified into two groups such as droplet-based and chamber-based systems. In this thesis, both droplet-based and chamber-based approaches were used to build the microfluidic methods for isothermal amplification assays.
First, a simple electromechanical probe (tweezers) was developed that can manipulate a small aqueous droplet in a bi-layer oil phase. The tweezer consisted of two needles positioned close to each other and used polarization of the aqueous droplet in an applied electrical field to confine the droplet between the needles with minimal solid contact. AC electric potential was applied to the two metal electrodes. Droplet acquired a charge from the high voltage electrode and consequently performed an oscillatory motion with the same electrode. This droplet motion was controlled using two parameters of electric potential and frequency of the applied signal. Initially, electrically actuated droplet (0.3 µL) motion was investigated for a range of applied potential (400-960 Volts) and frequencies (0.1-1000 Hz). The droplet motion with high voltage electrode was characterized into three modes such as detachment, oscillation, and attachment.
Mechanical motion of tweezer was used to transport droplet to various positions. Consequently, operations such as transportation, extraction, and merging were demonstrated. First, droplet (5 µL) transportation was characterized under the applied potential of 2000 Volts at various frequencies (5 to 1000 Hz). The droplet was successfully transported to the speed of 15 mm/s at higher frequencies (100 or 1000 Hz). Droplets of various volumes (12-80 µL) were extracted by increasing applied electric potential, from 0 to 6000 Volts at 5 Hz. Then, the operation of droplets merging was demonstrated using operational conditions for electrical tweezer.
Finally, electrical tweezer was used to prepare samples for isothermal amplification assays. Two droplets consisted of various reagents of isothermal amplification assays, were transported and merged using the electrical tweezer. Then, a merged droplet (25 µL) was transported and immobilized in the amplification zone. The temperature of the amplification zone (~65°C) was maintained using an in-situ heater. DNA amplification was verified by measuring the off-chip end-point fluorescence intensity of isothermal assays.
Second, an integrated microfluidic device has been developed to prepare a sample for isothermal amplification assays. And in-situ real-time amplification assays were performed to detect bacteria. The device consisted of two chambers (lysis and amplification) connected through a microchannel. A low-cost fabrication method was introduced to embed two resistive wire heaters around both chambers. Initially, bacteria cells were thermally lysed in the lysis chamber at 92°C for 5 min. Then, DNA was electrophoretically transported from lysis to the amplification chamber. The electric potential of 10 Volts was applied for 10 min for DNA transportation. Next, transported DNA was amplified at 65°C and DNA amplification was detected by measuring in-situ fluorescence intensity in the real-time format. The operation of the integrated microfluidic device was demonstrated in three steps. 1) Operation of individual components. 2) Operation of two components in a coupled format. 3) Integrated operation of three components with measurement of fluorescent intensity in a real-time format. The bacteria samples with the concentration of 100 CFU/mL were detected in less than one hour.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Kinetic Study of Thermal Decarboxylation of Substituted Sodium Phenylpropiolates

contributor:
Bourne, A. N.
Chemistry

subject:
kinetic
thermal decarboxylation
decaroboxylation
sodium phenylpropiolates

abstract: The kinetics of the thermal decarboxylation of a series of substituted sodium phenylpropiolates were studied in detail. The reaction proceeded without formation of significant amounts of side products: its rate was independent of hydrogen ion concentration. The relative rates of decarboxylation are in the order: p-NO2 > m-NO2> m-CF3 > m-Cl > p-Cl > H > m-CH3, and the entropies of activation are large and positive. The results were discussed in terms of the unimolecular (SE1) mechanism. A quantitative study of effects of substituents on the decarboxylation rates was made by the application of the Hammett free energy relationship. The e value of the Hammett plot was 0.886 +/- 0.013. Deviation of para substituted compounds from the Hammett relationship were discussed in terms of para interaction or conjugation effects in the initial or the transition states.

abstract: Thesis

abstract: Master of Science (MS)


title: Diffraction of 3.2 cm Microwaves by a Conducting and a Dielectric Rod With Diameter of the Order of a Wave-length

title: Diffraction of Microwaves

contributor:
McLay, A.B.
Physics

subject:
diffraction
microvwaves
dielectric rod

abstract: A description of the apparatus used in microwave phase and diffraction measurements is contained in the first chapter of this thesis. The field was investigated by a phase technique and the point source of radiation reasonably well established. Several diffraction patterns about a dielectric and a conducting rod were taken at several distances behind the rod with E vector of the field parallel to the axis of the rod. These were qualitatively analysed and compared with the patterns of one other worker at 1.25 cm. Agreements and differences were noted.

abstract: Thesis

abstract: Master of Science (MS)


title: THE IMPACT OF SOLID FOOD INTRODUCTION ON MICROBIAL SUCCESSION IN THE INFANT GUT

title: SOLID FOOD INTRODUCTION AND THE INFANT GUT MICROBIOME

contributor:
Stearns, Jennifer
Health Sciences

abstract:
Succession of the gut microbial community in infancy is marked by natural disturbances
such as the introduction of solid food, the details and timing of which may be important
factors in shaping the microbiome and, ultimately, human health. Previous gut
microbiome studies focused on molecular profiles of bacterial communities generated
through amplicon-based sequencing or metagenomics. Although providing a genus level
profile of the microbiome, this approach does not functionally address microbial
metabolism or interactions. This thesis explores the impact of solid food introduction on
the developing gut microbiome of a breastfed, vaginally-born infant from the Baby & Mi
prospective birth cohort. To investigate this, we designed a targeted culture strategy to
complement molecular profiling and applied it to a longitudinal sample over a period of
25 days during the transition to solid foods. Upon observing community and specieslevel
changes throughout the course of the study, we were prompted to explore strainlevel
and functional changes over that period. This was executed using bacterial
functional phenotype screens, to measure bacterial strain metabolism of fiber substrates
for genera of interest. Data show that our targeted culture strategy is more sensitive than
16S rRNA gene sequencing of stool alone at capturing bacteria of interest in the infant
gut. Using this culture strategy, we show that alpha diversity is primarily driven by
species evenness rather than richness following solid food introduction. Additionally,
some phylotypes within the same genus show different patterns of change in relative
abundance following solid food introduction. To explore this further, we use cultured isolates from the longitudinal study and
show that different isolates of the same species may utilize substrates differently (e.g.
Enterococcus faecalis, Bacteroides ovatus) and others may utilize substrates in the same
way (e.g. Bifidobacterium breve, Paeniclostridium sordelli). We also show that isolates
of the same species acquired before solid food introduction may differ from ones acquired
after (e.g. Enterococcus faecalis), or may remain the same (e.g. Bifidobacterium breve).
Combining targeted-culturing with molecular profiling methods such as 16S rRNA gene
sequencing and metagenomic approaches can provide us with more comprehensive and
detailed functional data regarding how the gut microbiome responds to a disturbance,
such as solid food introduction, during infancy.

abstract: Thesis

abstract: Master of Health Sciences (MSc)


title: Computational Strategies for Dynamic Analysis of Reinforced Concrete Structures Subjected to Blast Loading

contributor:
El-Dakhakhni, W.W.
Civil Engineering

subject: computational strategies. reinforced concrete structures, blast bloading, computational strategies for dynamic analysis, dynamic analysis, concrete structures subject to blast loading

abstract:
There has always been a challenge for designing structures against extreme dynamic loads. Blast loading falls under these loads category and blast resistant design has been gaining more interest during the past decade. Among different types of structures, Reinforced Concrete (RC) structures are usually recommended to be used for blast resistant design. However, the nonlinearities associated with these structures make their accurate analysis complicated. Therefore, simplified techniques have been introduced for nonlinear dynamic analysis of these structures. This study focuses on developing simplified computational strategies for the dynamic analysis of blast
loaded RC elements including beams, panels/slabs and columns. For RC beams, the basis for commonly used Single-Degree-of-Freedom (SDOF) models has been outlined. A Multi-Degrees-of-Freedom (MDOF) model which takes into account the concrete nonlinear properties has been developed and the effect of varying the number of degrees-of-freedom (DOF) on response has been studied. Results showed that increasing the number of DOF affects the pressure-impulse (P-I) diagrams, especially in the impulsive regime, as the extent of damage increased. In addition, the model was compared with the experimental data and showed good agreement. For RC panels,
a SDOF technique, based on the US Army Technical Manual TMS-1300 instructions, was
constructed and results were compared with the ones obtained from explicit Finite Element (FE) analysis. Compared to the FE results, SDOF model yielded conservative predictions for deflection but it usually underestimated the dynamic reactions. A modification for reaction calculation was proposed which resulted in significantly better prediction of the reaction for the impulsive range of loading. Finally, considering the important role of columns in providing the overall stability of the structure, a MDOF model was developed for RC columns and the load carrying capacity of the columns was investigated for different levels of axial load, strain rate and damage. Increasing the strain rate enhanced the column's cross section properties whereas increasing the levels of axial load reduced the cross section curvature and the column deflection capacities. Results also showed that good detailing at the supports can significantly improve the load carrying capacity of RC columns.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: F5TeO–Derivatives and NgF2 (Ng = Kr, Xe) Coordination Complexes of Hg(II), and a Xe(II) Oxide Cation

contributor:
Schrobilgen, Gary J.
Chemistry and Chemical Biology

subject: krypton mercury xenon teflate fluorine

abstract: The research described in this Thesis investigates the coordination chemistry of pentafluorooxotellurate(VI) (F5TeO– or “teflate”) and [PnF6]–  (Pn = As, F) derivatives of mercury(II), and expands the chemistry of Ng(II) (Ng = Kr, Xe) by characterizing several NgF2 coordination complexes with mercury, and the synthesis of a new xenon(II) oxide cation. The compounds discussed herein were characterized predominately by low-temperature single-crystal X-ray diffraction and Raman spectroscopy, and were frequently complemented by quantum-chemical calculations. The chemistry of the F5TeO–group was developed for Hg(II) derivatives by investigating the Lewis acid properties of Hg(OTeF5)2. Initial efforts investigated interactions with the nitrogen base NSF3, and resulted in the coordination complexes [Hg(OTeF5)2∙N≡SF3]∞, [Hg(OTeF5)2∙2N≡SF3]2, and Hg3(OTeF5)6∙4N≡SF3 at 0oC. Although the F5TeO–group often bonds in a monodendate fashion, these less sterically saturated salts result in oxygen bridging in the solid state. In Hg3(OTeF5)6∙4N≡SF3, oxygen bridging between three metal centers by the pentafluorooxotellurate(VI) group is observed for the first time. The nature of this new bonding was further analysed computationally for Hg3(OTeF5)6∙4N≡SF3 by natural bond orbital analyses (NBO). At room temperature, reactions of Hg(OTeF5)2 with NSF3 resulted in O/F metatheses to yield related F2OSN–derivatives, namely [Hg(OTeF5)(N=SOF2)∙N≡SF3]∞ and [Hg3(OTeF5)5(N=SOF2)-∙2N≡SF3]2, accompanied by the elimination of TeF6 as confirmed by 19F NMR spectroscopy. In related work, the acceptor properties of  Hg(OTeF5)2 were further investigated in its reactions with M[OTeF5] (M = [N(CH3)4]+, [N(CH2CH3)4]+, Cs+) to form a series of teflate anion salts; [N(CH2CH3)4]2[Hg(OTeF5)4], [N(CH3)4]3[Hg(OTeF5)5], [N(CH2CH3)4]3[Hg(OTeF5)5], [N(CH3)4]2[Hg2(OTeF5)6], Cs2[Hg(OTeF5)4]•Hg(OTeF5)2, and {Cs3[Hg2(OTeF5)7]•Hg(OTeF5)2}•4SO2ClF. In comparison to their halide counterparts, the less basic and more sterically demanding teflate ligands of the Hg(II) anions show less tendency to extensively bridge. The Raman spectra of the [Hg(OTeF5)4]2−, [Hg(OTeF5)5]3−, and [Hg2(OTeF5)6]2− anions were fully assigned with the aid of their calculated gas-phase vibrational frequencies. NBO analyses further probed the bonding in the anions. The [Hg(OTeF5)5]3− anion provides an unusual square-pyramidal coordination sphere around mercury and the only presently known teflate-substituted anion with a net charge of 3–. In related work, the weakly coordination anion (WCA) [Sb(OTeF5)6]– was substituted in Hg2+ salts using weakly coordinating SO2ClF solvent to give the homoleptic solvent complex, [Hg(SO2ClF)6][Sb(OTeF5)6]2. The ability of this salt to function as a precursor for other ligands was demonstrated by the reaction with the nitrogen bases NCR (R = –CH3 or –CH2CH3) which resulted in the isolation and full characterization of the corresponding homoleptic nitrile complexes [Hg(NCR)5][Sb(OTeF5)6]2ꞏ2SO2ClF. Gas-phase energy-minimized calculation of the cations aided in the vibrational assignment of the Raman spectra, whereas NBO and counterpoise corrected binding energies give insights into the strength of the metal-ligand bonds and resulting electronic effects of these interactions. The established Lewis acidity of Hg(OTeF5)2, and known oxidative resistance of the F5TeO–group, were exploited to form rare examples of noble-gas difluoride adducts, Hg(OTeF5)2•1.5NgF2 (Ng = Xe, Kr). The isostructural complexes were fully characterized, and the KrF2 adduct provided only the second crystallographically characterized KrF2 complex and the first example of bridge coordination by KrF2¬.	The chemistry of krypton was significantly extended by further exploring the little studied coordination of KrF2 with the salts Hg(PnF6)2 (Pn = As, Sb) and FHg(AsF6), leading to an important series of coordination complexes.	The first homoleptic KrF2 coordination complex, [Hg(KrF2)8][AsF6]2•2HF, was thoroughly characterized by single-crystal X-ray diffraction, Raman spectroscopy, and quantum-chemical analyses. It provides the highest KrF2-to-metal ratio that is currently known for a coordination complex. The bonding was extensively analysed by NBO, calculated binding energies, energy decomposition analyses (EDA), and Extended Transition State Natural Orbitals for Chemical Valence (ETS-NOCV) analyses. This computational work suggests that both orbital interactions, which incorporate covalent bonding, and electrostatic contributions are important stabilization factors and that the 8σg (HOMO‒4) orbital and, to a lesser extent, a degenerate 4πu (HOMO) orbital, derived from free KrF2 (D∞h) are involved in adduct formation. This result helps to rationalize the observed M---F–Kr(F) coordination angles observed for most terminally coordinated NgF2 complexes. A series of related complexes with one to five KrF2 molecules per metal center were also characterized by single-crystal X-ray diffraction, namely Hg(KrF2)(HF)(AsF6)2 (1), Hg(KrF2)2(AsF6)2 (2), Hg(KrF2)3(HF)(SbF6)2 (3), [Hg(KrF2)4(HF)2(SbF6)]2[SbF6]2 (4), Hg(KrF2)5(AsF6)2 (5), Hg(KrF2)4(HF)2(AsF6)2•HF (6), FHg(μ3-FKrF)1.5(KrF2)0.5(AsF6) (7), and FHg(μ3-FKrF)0.5(KrF2)1.5(AsF6) (8). These complexes were unambiguously characterized by single-crystal X-ray diffraction which showed that the structures became more extensively linked due to bridging between mercury and the [PnF6]‒ anions as the number of coordinated KrF2 ligands decreased. While compounds (1)-(6) solely contain terminally coordinated KrF2 ligands, compound (7) also contains the second structurally characterized example of KrF2 bridging two metal centers through each of its fluorine atoms. Replacement of [AsF6]‒ by F‒ in compounds (7) and (8) also resulted in the first examples of a new bonding modality of KrF2, where only one of the fluorine atoms bridges two different metal centers. The Raman spectrum of (5) was assigned with the aid of calculated gas-phase vibrational frequencies. Natural bond orbital (NBO) analyses of [Hg(KrF2)5][AsF6]2 are consistent with coordinate covalent ligand-metal interactions. The nature of bonding for the unprecedented KrF2 bonding modality was further probed computationally with EDA and ETS-NOCV analyses and corroborate an MO description where electron density is donated from both the 8σg (HOMO‒4) and a degenerate 4πu (HOMO) molecular orbital of KrF2 to LUMOs involving the 6s and 6p orbitals of each mercury atom.  To further expand the chemistry of the noble-gases, the second known xenon(II) oxide, [XeOXe]2+, was synthesized from the reaction of [FXeOXe---FXeF][AsF6] and acetonitrile at low-temperatures in anhydrous HF. The cation was isolated in macroscopic quantities as its well-isolated adduct-dication [CH3CN---XeOXe---NCCH3][AsF6]2 salt and was fully characterized by single-crystal X-ray diffraction and 16/18O isotopic enrichment Raman studies. The [XeOXe]2+ adduct-cation provides an important example of σ-hole bonding by a nitrogen base to a Xe(II) atom. The nature and strength of the Xe–O and Xe–N bonds in the calculated gas-phase [XeOXe]2+ and [CH3CN---XeOXe---NCCH3]2+ cations were extensively explored using a range of quantum-chemical (QC) methods, namely, NBO, atoms in molecules (AIM), electron localization function (ELF), and molecular electrostatic potential surface (MEPS) analyses.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: The coordination chemistry of pentafluorooxotellurate(VI) (F5TeO– or “teflate”) derivatives, as well as [PnF6]–  (Pn = As, Sb) salts,  of mercury(II), and the chemistry of Ng(II) (Ng = Kr, Xe), are the major focuses of this Thesis. The Lewis acid properties of Hg(OTeF5)2 were investigated using the nitrogen base, NSF3, and M[OTeF5] salts (M = Cs+, N(CH3)4+, N(CH2CH3)4+) which resulted in a series of NSF3 adducts, F2S(O)N– derivatives, and several anions. Reactions of Hg(OTeF5)2 with NgF2 also provided rare examples of bridging NgF2 coordination complexes. Routes to [Sb(OTeF5)6]– salts containing weakly-solvated Hg2+ cations was developed, which provided an important synthetic precursor to explore further ligand substitution reactions at Hg2+. The relatively unexplored chemistry of krypton was further advanced by synthesizing a series of coordination complexes of KrF2 with Hg(PnF6)2 and FHg(AsF6) salts, providing rare examples of terminally coordinated and bridging KrF2 ligands, and a new coordination mode for KrF2 molecules. Advances in the chemistry of Xe(II) were also made through the synthesis and characterization of the second known, and simplest, xenon(II) oxide species. Characterization methods employed in this Thesis predominantly were single-crystal X-ray diffraction and Raman spectroscopy. Quantum-chemical calculations aided with Raman assignments, and were used to further investigate the nature of chemical bonding in the compounds that had been synthesized. The research described in this Thesis significantly contributes to and extends the chemistry of the pentafluorooxotellurate(VI) ligand, to our knowledge and understanding of the reactivity and bonding of krypton(II) and xenon(II) species, and most notably, the coordination chemistry of KrF2.


title: The Influence of Loss of Bond on the Mechanics of Failure of Reinforced Concrete Beams

title: Loss of Bond in the Reinforced Concrete Beam

contributor:
Robinson, H.
Civil Engineering

subject:
loss of bond
mechanics of failure
concrete beams
concrete

abstract: This thesis involves the consideration of the reinforced concrete beam as a composite beam with incomplete interaction. The influence of bond slip and loading condition on the formation of cracks is studied analytically.

abstract: Thesis

abstract: Master of Engineering (ME)


title: Modification and Characterization of Alpha and Beta Nickel (II) Hydroxide

contributor:
Botton, Gianluigi A.
Materials Science and Engineering

abstract: I have submitted another pdf file which is my permissions for figures used in my thesis. The name this file is Clearance.

abstract: Nickel Hydroxide is one of highly active materials used in various energy conversion applications. One of the key factors in the deposition of Ni(OH)2 is the active surface area which plays an important role in improving the efficiency of transformation reactions. There are various methods to enhance the active area. One method that can be used to modify the morphology of deposited Ni(OH)2 is to generate porous structures. Ni(OH)2 can be formed in two different phases namely alpha and beta. The main objective in our work is to optimize the synthesis conditions and characterize structures at the nanoscale, and also demonstrate unequivocally the presence of alpha and beta phases. For this work, a combination of electron microscopy and electrochemistry is needed to modify the morphology of nickel hydroxide and for detailed structural characterization. Various characterization techniques are used to investigate different electrochemical depositions conditions of Ni(OH)2 in alpha and beta phase forms using Direct and Indirect methods, respectively. Kinetically, alpha-Ni(OH)2 is easier and faster to be synthesized and can be deposited directly in one step. During cyclic voltammetry of alpha-Ni(OH)2 in KOH, the volume of material involved in the oxidation reaction increases in every cycle. Scanning Electron Microscopy and Transmission Electron Microscopy characterization shows that this may be due to microbubble formation that transform deposited sheets to particulate shapes. On the other hand, conversion of nickel metal to beta-Ni(OH)2 during cyclic voltammetry causes an expansion of particles. Effectively, nickel hydroxide is formed on the shell while nickel remains in the core. High Resolution Transmission Electron Microscopy is then used to identify the distribution of these phases. Another foremost feature for the beta phase is to make nickel metal in any desired shape, which can then be converted to beta-Ni(OH)2 through Cyclic Voltammetry in KOH. The presence of both phases is demonstrated with electron diffraction. Finally, as future work, all experiments will be performed in-situ TEM using liquid cell to observe structural changes in real time.

abstract: Thesis

abstract: Master of Science (MSc)


title: Characterization of a Herpes Simplex Virus T Cell Immune Evasion Strategy

contributor:
Johnson, David
Biology

subject:
herpes simplex virus
herpes
t cell
immune evasion strategy
immune

abstract: Herpes simplex virus (HSV) infections are common in all human populations and for most people they represent relatively mild lifelong infections. To facilitate the persistent infection of hosts, HSV has evolved immune evasion strategies which suppress various aspects of the immune response including the actions of complement and antibodies. Previously in our laboratory, an HSV immediate early protein called ICP47 was shown to inhibit the MHC class I antigen presentation pathway and thereby block recognition of virus infected cells by CD8+ cytotoxic T lymphocytes (CTL). This thesis explores the potential cellular targets of ICP47. Using immunoprecipitation I found ICP47 associates with the transporter associated with antigen presentation (TAP). By blocking the transport of peptide antigens into the endoplasmic reticulum, MHC class I molecules become unstable and are subsequently degraded before displaying HSV antigens on the cell surface. Thus, CTL destruction of cells infected with HSV is blocked. In addition, an interaction between an ICP47 bacterial fusion protein, called GSTICP47-1 and a cellular protein, calcyclin, was examined. The functions of calcyclin are largely unknown. However, based on its association with ICP47, it was possible that calcyclin might play a role in the class I pathway -perhaps as the peptide shuttle. Nevertheless, the results of several experiments were consistent with the notion that calcyclin and ICP47 may not interact in vivo and that calcyclin may not play a role in the MHC class I antigen presentation pathway.

abstract: Thesis

abstract: Master of Science (MS)


title: Deep Reinforcement Learning Adaptive Traffic Signal Control

title: Reinforcement Learning Traffic Signal Control

contributor:
Razavi, Saiedeh
Civil Engineering

subject: deep reinforcement learning adaptive traffic signal control

subject: reinforcement learning traffic signal control

subject: intelligent transportation systems

subject: machine learning

subject: machine learning transportation

subject: machine learning traffic signal control

subject: artificial intelligence

subject: artificial intelligence transportation

subject: deep learning

subject: deep neural networks

subject: traffic optimization

subject: adaptive traffic signal control

subject: machine learning engineering

abstract: Sub-optimal automated transportation control systems incur high mobility, human health and environmental costs. With society reliant on its transportation systems for the movement of individuals, goods and services, minimizing these costs benefits many. Intersection traffic signal controllers are an important element of modern transportation systems that govern how vehicles traverse road infrastructure. Many types of traffic signal controllers exist; fixed time, actuated and adaptive. Adaptive traffic signal controllers seek to minimize transportation costs through dynamic control of the intersection. However, many existing adaptive traffic signal controllers rely on heuristic or expert knowledge and were not originally designed for scalability or for transportation’s big data future. This research addresses the aforementioned challenges by developing a scalable system for adaptive traffic signal control model development using deep reinforcement learning in traffic simulation. Traffic signal control can be modelled as a sequential decision-making problem; reinforcement learning can solve sequential decision-making problems by learning an optimal policy. Deep reinforcement learning makes use of deep neural networks, powerful function approximators which benefit from large amounts of data. Distributed, parallel computing techniques are used to provide scalability, with the proposed methods validated on a simulation of the City of Luxembourg, Luxembourg, consisting of 196 intersections. This research contributes to the body of knowledge by successfully developing a scalable system for adaptive traffic signal control model development and validating it on the largest traffic microsimulator in the literature. The proposed system reduces delay, queues, vehicle stopped time and travel time compared to conventional traffic signal controllers. Findings from this research include that using reinforcement learning methods which explicitly develop the policy offers improved performance over purely value-based methods. The developed methods are expected to mitigate the problems caused by sub-optimal automated transportation signal controls systems, improving mobility and human health and reducing environmental costs.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: Inefficient transportation systems negatively impact mobility, human health and the environment. The goal of this research is to mitigate these negative impacts by improving automated transportation control systems, specifically intersection traffic signal controllers. This research presents a system for developing adaptive traffic signal controllers that can efficiently scale to the size of cities by using machine learning and parallel computation techniques. The proposed system is validated by developing adaptive traffic signal controllers for 196 intersections in a simulation of the City of Luxembourg, Luxembourg, successfully reducing delay, queues, vehicle stopped time and travel time.


title: Population Genetic Structure of Beluga Whales Delphinapterus leucus Mitochondrial DNA Sequence Variation Within and Among North American Populations

contributor:
White, Bradley
Biology

subject:
beluga whale
delphinapterus leucas
mitochondrial DNA
North America
population

abstract: Beluga whales are migratory over much of their range, congregating in small groups around shallow river estuaries in summer, and overwintering in large groups in areas with reliable open water. This complicates management issues because it is unclear if belugas from the common wintering ground represent one large group with exchange of individuals, or if each summer estuarine concentration should be managed as a separate stock. To examine the genetic structuring, we analyzed variation in mitochondrial DNA (mtDNA) restriction sites among 101 beluga whales from 10 regions across North America, including Greenland. Using 11 restriction enzymes, 9 haplotypes were identified among 71 whales. The remaining 30 whales were tested with only the six restriction enzymes found to identify polymorphisms. We found a marked segregation of divergent haplotypes for both sexes between eastern and western Hudson Bay. Haplotype 1 was found in 19 out of 21 animals on the east coast, while haplotype 5 was found in 18 out of 20 animals on the west coast. Sequence divergence among the 71 belugas was estimated to be 2.03%. Haplotypes fell into two major phylogenetic groups, labelled lineage I and II. Lineage I haplotypes occurred primarily in the St. Lawrence Estuary and the eastern Hudson Bay. Lineage II haplotypes occurred primarily along the western Hudson Bay, Southern Baffin Island, western Greenland, the Canadian high arctic, and the Beaufort Sea. These findings support the hypothesis that belugas exhibit maternally directed philopatry to summering grounds, and are consistent with the hypothesis that after deglaciation, the arctic was recolonized by at least two stocks of belugas divergent in their mtDNA, possibly representing Atlantic and Pacific stocks.

abstract: Thesis

abstract: Master of Science (MS)


title: The Evolution of Sinorhizobium meliloti.

contributor:
Golding, Dr. G. Brian
Biology

subject:
evolution
sinorhizobium meliloti

abstract: The genome of the a-proteobacterium Sinorhizobium meliloti has been completely sequenced and annotated. providing a wealth of information about this endosymbiotic N2 fixing organism. Although the structure of the genome, consisting of a circular chromosome and two smaller pSymA and pSymB replicons, has long been known, only a small portion of ORFs have previously been characterized. Sequence analysis of pSymB has revealed that a large portion of the 1570 ORFs code for solute uptake systems and polysaccharide biosynthesis. The pSymB replicon been referred to as a "megaplasmid," implying that pSymB is non-essential for viability of the organism. However, coded on pSymB are several essential genes, including a tRNA ArgCCG gene and the minCDE genes, which are not found elsewhere in the genome. Replication of pSymB is controlled by repABC genes, a typical property of plasmids among Rhizobiaceae. Therefore, the genome signature, a compositional analysis that allows comparison of whole replicons rather than focusing on particular genes, was used to provide support for designation of pSymB as a second chromosome in S. mdiloti. It was found that among a-proteobacteria, plasmids and chromosomes have distinctive patterns of dinucleotide biases, and in this respect, pSymB is chromosome-like while pSymA is plasmid-like. This brings into question how the pSymB replicon came to acquire chromosome-like properties while appearing to be maintained as a plasmid in the genome. Whole-genome nearest neighbor analysis shows that the linear chromosome of Agrobacterium tumefaciens and pSymB may have a common origin. Despite conservation of gene order within small groups of genes, it is evident that rearrangements, duplications, and horizontal transfer of genes since the divergence of these species have contributed to the mosaic nature of pSymB. Since synteny between the S. meliloti chromosome and A. tumefaciens circular chromosome is highly conserved, it appears that the instability of pSy mB has played a key role in the adaptation and evolution of S. meliloti.

abstract: Thesis

abstract: Master of Science (MS)


title: An Evaluation of the Pollutants Entering Ontarios Wetlands: How Landuse Impacts Wetland Health

contributor:
Chow-Fraser, Patricia
Biology

subject:
pollutants
landuse impact
ontario wetland
wetland health

abstract: To assess the impacts of non-point source pollution on Ontarios wetlands I examined the landuse in the watershed, the water and sediment quality, and the aquatic vegetation in 22 wetlands. I characterized the primary contaminants that enter marshes in Ontario and relate their concentrations to the relative amounts and types of land use in their watershed. I measured levels of nutrients, suspended particulates and trace organics in water and sediment. Species richness and structural diversity of the vegetative community was used as an indicator of wetland health. I included a comparison of two techniques, immunoassays and gas-chromatography (GC) to measure trace organics (PAHs and metolachlor; Chapter 1). Comparison of results from both techniques indicated that immunoassays overestimated analyte concentration by approximately a third. I utilized the immunoassay results, along with selected water quality variables, to characterize contaminants entering these wetlands (Chapter 2). Watersheds containing greater than 95% agriculture contributed the highest suspended particulate, compared with those dominated by urban or forested land. Using multivariate statistics I identified important water and sediment variables that structured these wetlands to be: total phosphorus (TP), ammonia nitrogen (TAN), suspended solids (TSS), specific conductance (COND), sediment phosphorus CTPsed) and inorganic material (lnorgsed) in the sediment. Of these TP, COND and Inorgsed were negatively related to the submergent plant community, while TPsed was positively related. There was no relationship between water quality and the floating or emergent plants but the structural diversity of the plant community was negatively affected by poor water quality. The negative impact of developed land in the watershed on the health of the aquatic plant communities underscores the need to maintain natural areas to trap nutrients and sediments in runoff.

abstract: Thesis

abstract: Master of Science (MS)


title: Basic Fibroblast Growth Factor (FGF-2) Delivery From Heparin Modified Surfaces for Artificial Cornea Applications

title: FGF-2 Delivery from Heparinized PDMS and Collagen Materials

contributor:
Sheardown, Dr. H.
Chemical Engineering

subject:
basic fibroblast growth factor
heparin modified materials
artificial cornea applications

abstract:
Device anchoring of artificial cornea implants, through tissue integration of
stromal tissue, is necessary to ensure long-term success. In this work, the delivery of
basic fibroblast growth factor (FGF-2), a key modulator in corneal wound healing, via
heparin modified materials was investigated as a means of sustained, soluble growth
factor delivery for stimulation of device anchorage. Two materials types, commonly used
for ophthalmic applications and currently under investigation for use in artificial cornea
applications, were utilized. Poly (dimethyl siloxane) (PDMS) is currently under
investigation as the base material for keratoprosthetic devices; dendrimer crosslinked
collagen has been examined as the basis for use as a tissue engineered corneal equivalent.
PDMS surfaces were modified directly or indirectly, through a poly (ethylene
oxide) (PEO) spacer, to contain functionalized reactive NSC groups capable of binding
heparin and FGF-2 Surface modifications were characterized with attenuated total
reflection Fourier transform infrared spectrophotometer (ATR-FTIR), X-ray
photoelectron spectroscopy (XPS) and water contact angles. Heparin coverage was
assessed with metachromatic and bioactivity assays. Heparinized collagen gels were crosslinked with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC), N-hydroxysuccinimide (NHS) and polypropyleneimine octaamine G2 dendrimers. Gel integrity was assessed with water uptake, differential sr::anning calorimetry, and heparin and dendrimer stability. Both materials were exposed to radiolabelled FGF-2 and growth factor
immobilization and delivery were quantified. Heparinized PDMS surfaces were capable
of binding on average 100 ng/cm2 ofFGF-2, while heparinized collagen gels had higher
FGF-2 immobilization, 300 ng, likely attributed to their higher heparin densities and the
fact that the bulk gel rather than the surface only was modified. Delivery of FGF-2 from
the heparinized materials revealed a first order release profile, with an initial burst of
FGF-2, followed by gradual growth factor release. Release rates, over a 2 week period,
reached 6.5% and 50%, for 1 day and 3 day FGF-2 exposed heparinized PDMS modified
surfaces, while hepruinized dendrimer crosslinked collagen gels released 40%.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: Spatial and Temporal Variations in Fire Frequency in the Boreal Forest of Northern Alberta

title: Variations in Boreal Forest Fire Frequency

contributor:
MacDonald, Dr. G.M.
Geography

subject:
spatial variations
temporal variations
fire frequency
boreal forest

abstract:
Forest fires occur frequently in the boreal forest of North America and greatly affect vegetation dynamics, biogeochemical cycles and resident human populations. Estimates of the frequency of boreal forest fires would be useful for understanding boreal ecosystems and managing the affects of fires on human populations. The objectives of this work were to investigate relations between fire frequency and climate change, vegetation)n type and waterbreaks in Wood Buffalo National Park (WBNP), located in northern Alberta. To address these objectives, four hypotheses were tested: 1) tree ring-width records from the boreal forest can provide a proxy climate record; 2) annual area burned in the boreal forest varies in response to climate changes; 3) boreal fores: fire frequency varies with differences in forest type and the proximity to waterbreaks and 4) fossil pollen and macroscopic charcoal records from massive lake sediments can provide meaningful estimates of local fire frequency.
The first hypothesis was tested by constructing tree ring chronologies from 3 white spruce and two jack pine sites in WBNP. All five chronologies were significantly positively correlated with June precipitation in the growth year or the previous year, and were significantly negatively correlated with historical records of fire weather and annual area burned.
The second hypothesis was tested by analyzing historical records of annual area burned and climate. and tree ring records of fire history and climate. Annual area burned was significantly negatively correlated with seasonal means of fire weather indices. The time since last fire was estimated using tree ring records from 166 sites located throughout WBNP. These records exhibited decadal and centennial scale variations in fire frequency. Comparisons with tree ring other proxy climate records suggest that the~e variations are related to climatic changes.
The third hypothesis was tested using survival analysis of the time since last fire records, disaggregated by dominant vegetation and the mean distance to waterbreaks. Sites dominated by jack pine (Pinus banksiana) and aspen (Populus tremuloides) exhibited significantly higher fire frequencies than did sites dominated by black spruce (Picea mariana) or white spruce (Picea glauca). Fire frequency increased with increased mean distance to waterbreaks. The fourth hypothesis was tested by analyzing fossil pollen and charcoal records from two lakes at -5 year resolution for 600 years. I compared their fire history records with local tree ring records of fire, and their mean fire intervals with regional fire frequency estimates for sites with similar vegetation and mean distances to waterbreaks. One lake exhibited a meaningful fire frequency estimate and the other lake did not. The poor fire frequency estimate was related to high sediment mixing and the lack of homogenous vegetation around the lake. The results indicate that: 1) area burned and fire frequency in the boreal forest of northern Alberta varies temporally at the annual, decadal and centennial scales; 2) fire frequency varies spatially in relation to vegetation type and mean waterbreak distance; and 3) lakes with massive sediments can provide meaningful estimates of local fire frequency.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Applications of Nitrogen Isotopes and Other Tracers of Anthropogenic Input to Modern Reefs

contributor:
Risk, Dr. M.J.
Geology

subject:
nitrogen isotopes
modern reefs
anthropogenic input

abstract:
I investigated the use of nitrogen isotopes as a tracer of sewage contamination on coral reefs. Sewage is isotopically distinct from marine nitrogen, allowing its use as a tracer in this environment. Emphasis was placed on sampling modem coral tissues, as modern coral reefs are in a rapid state of decline, possibly as a result of sewage contamination.
Samples were collected in Zanzibar for two separate studies. The first study involved sampling over a depth/light gradient on large coral heads. These data, when combined with data from Jamaica, show light is a controlling factor on the nitrogen isotopic composition of coral tissue. Regression of delta15N of coral tissue with depth/light attenuation explains 75-90% of the variance. Results indicate increased fractionation with depth, which is related to the symbiotic nature of corals. Light-sufficient, nitrogen-limited zooxanthellae ( in the coral tissue ) must diffusl! all available nitrogen, and there is little fractionation. At depth, light-limited, nitrogen-sufficient zooxanthellae fractionate nitrogen during assimilation processes.
These results have important implications for the use of nitrogen isotopes as a sewage tracer on reefs. In general, increased nutrients to the reef environment result in decreased water clarity, or lowered available light to the coral. This could lower the zooxanthellae's nitrogen requirements and allow fractionation (isotopic depletion). Corals have been shown to become reliant on heterotrophy in non-limiting nutrient conditions, related to loss of control over
their zooxanthellae. This suggests the delta15N of their tissues would reflect their diet (and therefore the source of contamination). The counteractive effects of these two factors suggests it may not be possible to resolve the source of eutrophication to corals using the isotopic signatures of their tissue. That is, if the contamination gradient is coincident with a gradient in the symbiotic relationship (i.e. from nutrient limited to nutrient non-limited) or trophic status, there is little possibility of resolution of sewage effects.
Results from the second sample suite from Zanzibar and a sample suite from Jepara Bay, Indonesia confirm this hypothesis. Zanzibar samples were collected at a eutrophied and non-eutrophied reef, and show no significant difference between isotopic data. This may be a result of distance from source, or the counter-effects of light. At Jepara Bay, samples were collected along a contamination gradient, from 2 point source discharges. Isotopic data show significant change along the gradient, with the entire bay eutrophied. Without delta15N from all potential nitrogen sources it is impossible to adequately conclude whether sewage was the contaminant using isotopes. Other data collected from these reefs do support the interpretation of anthropogenic contamination. These data include decline in coral and fish communities (determined using biological assays, Zanzibar), and increased heavy metal and chlorophyll-a concentrations (Jepara).
One control on nitrogen isotope composition of modern corals was identified, and others suggested. Results will remain enigmatic until sample suites including complete water chemistry, source chemistry, and light regime are interpreted.

abstract: Thesis

abstract: Master of Science (MSc)


title: Electrical Communication Between Different Cell Types in the Colonic Musculature

subject:
electrical communication
colonic musculature
cell types

abstract: The major cell types in the canine colon musculature are interstitial cells of Cajal (ICC), circular muscle (CM) cells and longitudinal muscle (LM) cells. In isolated muscle strip studies, spontaneous membrane potential oscillations (slow waves) are generated in the submucosal border of the circular muscle where a gap junctionally well-coupled network of ICC and CM is found. CM devoid of LM and submucosal pacemaker region (CM preparations) are spontaneously quiescent. The research undertaken was to understand the mechanism of slow wave propagation into the circular muscle and to investigate the consequences to the electrical activity in CM after coupling with different electrical activities from different cells types. Our results show that CM cells, although spontaneously quiescent because of high K+ conductance, are excitable and can actively participate in slow wave generation. The electrical oscillations induced in the CM preparations could easily be potentiated by an L-type Ca2+ channel activator, Bay K 8644, and abolished by a L-type Ca2+ antagonist, D600, suggesting involvement of the conductance in the induced activity. The induced oscillations are similar to the SLAPs in the longitudinal muscle which shows that it is not necessary to have a specialized pacemaker cells for generating SLAPs. Using a cross sectioned preparation with all intact muscle layers, we also showed that the heterogeneity in the electrical activity of CM, such as: the resting membrane potential gradient, depolarization of plateau potential in the myenteric border and "apparent" decay in slow wave amplitude, is due to electrical interactions between different intrinsic activities from different cell types. Morphological evidence was obtained for the possible communication pathways in the submucosal and the myenteric borders of the circular muscle. Different coupling mechanisms in different areas were hypothesized. In addition, the 3-dimensional aspects of the submucosal ICC network in the ca.nine colon were clarified.

abstract: Thesis

abstract: Master of Engineering (ME)


title: An Initial Characterization of Aquatic Invertebrate Community Structure in the Moose River Basin, Ontario

title: Aquatic Invertebrates of the Moose River Basin

contributor:
Kolasa, Dr. Jurek
Biology

subject:
aquatic invertebrate
community structure
moose river basin
ontario

abstract: The Moose River Basin in northern Ontario is an important large river system, however very little is known about its aquatic invertebrate community. As macro invertebrates are an integral part of river ecosystems, I conducted an initial assessment of the aquatic invertebrate community structure in the Moose River Basin, at both a fine, and a basin-wide, scale. The fine scale study used invertebrate data collected at five reaches within a 30km stretch of the Groundhog River. The examination of the invertebrate community at a basin-wide scale was accomplished using meta-analysis techniques on twenty-two studies conducted on various rivers within the Basin. The effect of the following factors on community structure were examined: i) the use of different sampling devices, ii) water depth, iii) substrate type, iv) sampling in two consecutive years, and v) spatial scale. I found that the use of various sampling devices resulted in significantly different estimates of community structure. This strongly suggests that consistent sampling protocols are necessary to effectively compare results within, and among, studies. The effect of water depth on community structure was inconclusive, as too few samples were collected to overcome the confounding effects of substrate type. Substrate type had a significant effect on community structure, with greater invertebrate richness and diversity found in fine substrate in the Groundhog River study, but with no consistent patterns at the basin-wide scale. Invertebrate richness and diversity did not differ significantly in the Groundhog River between two consecutive years. In both the fine-scale and the basin-wide studies, the distribution of aquatic invertebrates varied among sites within a river reach, and among reaches within a river. To further examine the biological and physical processes affecting community structure at the fine-scale, consistent sampling protocols should be employed, which may also allow basin-wide trends to emerge.

abstract: Thesis

abstract: Master of Science (MS)


title: Reduction Precedes Cytidylyltransfer Without Substrate Channeling in Distinct Active Sites of the Bifunctional CDP-Ribitol Synthase From Haemophilus Influenzae

title: Bifunctional CDP-Ribitol Synthase From H. Influenzae

contributor:
Brown, Dr. Eric D.
Biochemistry

subject:
cytidylyltransfer
CDP-ribitol synthase
haemophilus influenzae

abstract: CDP-ribitol synthase is a bifunctional reductase and cytidylyltransferase that catalyzes the transformation of D-ribulose 5-phosphate, NADPH and CTP to CDP-ribitol, a repeating unit presem in the virulence-associated polysaccharide capsules of Haemophilus influenzae type a and b (Follens et al., 1999, J Bacterial. 181: 2001). In the work described here, we investigated the order of the reactions catalyzed by CDPribitol synthase and conducted experiments to resolve the question of substrate channeling in this bifunctional enzyme. It was determined that the synthase first catalyzed the reduction ofo-ribulose 5-phosphate followed by cytidylyltransfer to oribitol 5-phosphate. Steady state kinetic measurements revealed a 650-fold kinetic preference for cytidylyltransfer too-ribitol 5-phosphate over o-ribulose 5-phosphate. Rapid mixing studies indicated quick reduction of o-ribulose 5-phosphate with a lag in the cytidylyltransfer reaction consistent with a requirement for the accumulation of Km quantities of o-ribitol 5-phosphate. Signature motifs in the C-terminal and N-terminal sequences of the enzyme (short chain dehydrogenase/reductase and nucleotidyltransferase motifs, respectively) were targeted with site directed mutagenesis to generate variants that were impaired for only one of the two activities (K386A and R18A impaired for reduction and cytidylyltransfer, respectively). Release and free diffusion of the metabolic intermediate o-ribitol 5-phosphate was indicated by the finding that equimolar mixtures of K386A and R18A variants were efficient for bifunctional catalysis. Taken together these findings suggest that bifunctional turnover occurs in distinct active sites of CDP-ribitol synthase with reduction of n-ribulose 5-phosphate, release and free diffusion of the metabolic intermeditate n-ribitol 5-phosphate followed by cytidylyltransfer.

abstract: Thesis

abstract: Master of Science (MS)


title: Characterization of the H10/A4 Region of Vesicular Stromatitis Virus G Protein and Effects of H2-H10/A4 Mutations of Fusogenic Functions

title: VSV G H10/A4 Mutants and H2-H10/A4 Double Mutants

contributor:
Ghosh, H.P.
Biochemistry

subject:
H10/A4 region
vesicular stomatitis
virus G protein
H2-H10/A4
mutations
fusogenic functions

abstract:
The vesicular stomatitis virus glycoprotein G is responsible for low pH mediated membrane fusion induced by the virus. Four linker insertion mutants (H2, H5, HIO, A4) of the G ectodomain were found to disrupt fusion and yet maintained all the requirements for proper folding and cell surface expression (Li et al., 1993). Site specific mutagenesis of residues 123 to 137, surrounding the H2 mutant, either blocked or shifted the pH optima and threshold of fusion to more acidic values with a concomitant reduction in cell-cell fusion efficiency (Zhang and Ghosh, 1994; Fredericksen and Whitt, 1995). The region is highly conserved among vesiculoviruses and was found to insert into lipid membranes by hydrophobic photolabelling (Durrer et al., 1995) suggesting a possible role for this domain as the fusion peptide. Site-directed mutagenesis of residues 190 to 210, surrounding the H5 insertion mutant, did not significantly affect fusion (Fredericksen and Whitt, 1995). Surrounding the H10 and A4 insertion mutants is a conserved region, residues 395 to 424, that does not interact with target membranes (Durrer et al., 1995). To determine the functional importance of this region, site-directed mutagenesis was employed. Substitution of conserved Gly 404, Gly 406, Asp 409, and Asp 411 with Ala, Ala, Asn, and Asn, respt:.ctively, both reduced fusion and caused a shift in the pH of fusion threshold to more acidic values (tested by Y. He as published in Shokralla et al., 1998). In this study, the Hl0/A4 region is further mutagenized and tested for fusion. Cell surface expression was examined by indirect immunofluorescence and lactoperoxidase catalyzed iodination. Rates of transport from the endoplasmic reticulum and oligomerization into trimers were tested by resistance to endoglycosidase H and sucrose density gradient centrifugation, respectively. Low-pH induced conformational changes were assayed by resistance to proteolytic digestion. Residues Gly 395, Gly 404, Gly 409 and Ala 418 were substituted with Glu, Lys, Asp, and Lys, respectively. All mutants, with the exception of A418K, were expressed at levels similar to or above wild-type. Mutants G404K and D409A completely abolished fusion. Mutant G395E reduced cell-cell fusion efficiency by 82% and shifted both the pH threshold and optimum of wild type fusion. Although all mutants were capable of trimer formation, alterations in the structure of mutants G404K, D409 A, and A418K were detected by slower transport rates. All Hl0/A4 mutants were more susceptible to trypsin than wild-tyr,e at the pH of6.5, and mutant G404K was completely susceptible at this pH Reductions in the extent of fusion, along with shifts in the pH optima and thresholds of fusion suggest that the Hl0/A4 region (residues 395 to 418) of vesicular stomatitis virus G protein is important for G mediated fusion. The region may influence low-pH induced conformational changes. Double mutants of the H2 and HI0/A4 regions were also tested for their effects on fusion. The extents of fusion mediated by double mutant G proteins were severely reduced with levels ranging from 28% wild-type fusion to complete fusion deficiency. Only mutant Gl31A G404A was capable of 83% wild-type fusion. Mutants Gl31A G395E, Gl31A G404A, Gl31A D4LIN, Dl37N G404A, and the fusion defective D137N D411N were expressed at levels above wild-type G protein at the cell surface. Mutants Fl25Y D411N and
Pl26L D411N, although capable of very low levels of fusion were not detectable at the cell
surface by immunoflorescence and were detected at low levels by lactoperoxidase catalyzed iodination of cell surface proteins. These two mutants, along with Gl31A G404A, also showed slower transport rates than wild-type G. All double mutants showed increased sensitivity to trypsin at the pH of 6.5 with mutant Fl25Y D411N showing complete susceptibility. They were also all capable of trimer formation by sucrose density gradient centrifugation. In comparing the fusion profiles of double mutants with those of their component single mutants, it was found that in most cases the pH threshold of fusion by double mutants was greater than the sum of the single mutants and that the pH optimum of fusion corresponded to that of the constituent H2 single mutant. Although, the regions are functionally independent, they may indirectly affect one another through alterations in protein structure.

abstract: Thesis

abstract: Master of Science (MS)


title: Influence of the Membrane Anchoring and Cytoplasmic Domains on the Fusogenic Activity of Vesicular Stomatitis Virus Glycoprotein G

subject:
membrane anchoring
cytoplasmic domains
fusogenic activity
vesicular stomatitis
virus glycoprotein g

abstract:
Relatively little is known about the vesicular stomatitis virus (VSV) glycoprotein G fusion mechanism. Vesicular stomatitis virus has a single type 1 integral membrane glycoprotein G embedded in the viral membrane. It is the only viral protein required for VSV induced low pH mediated fusion. Mutations in four regions (H2, A5, A4 and HI0) of the VSV G ectodomain have been shown to abolish the fusion activity of the viral
glycoprotein (Li et al.,l993). One region H2 (a.a 117-139) has been suggested to be the fusion peptide (Zhang and Ghosh, 1994)(Fredericksen and Whitt, 1995). Amino acids 59-221 of the G protein, an area that encompasses the H2 region, has recently been shown to interact with liposomes through hydrophobic photolabeling experiments (Durrer et al., 1995), suggesting that the H2 region (fusion peptide)is able to interact with hydrophobic target bilayers at low pH. A soluble VSV G protein lacking the transmembrane anchor and cytoplasmic tail of VSV G is not fusogenic, suggesting that G must be anchored to the plasma membrane to promote syncytia (Florkiewicz and Rose, 1984). To better understand the steps involved in the fusion mechanism of VSV G it is important to identify domains within the protein that are involved in the fusion process.
To determine the contributions of the transmembrane anchor and cytoplasmic tail to the VSV fusion mechanism chimeric G proteins were constructed. The transmembrane anchor alone or in conjunction with the cytoplasmic tail ofVSV G was replaced with equivalent domain from other viral proteins, HSV-1 glycoproteins gB and gD, adenovirus E3 11.6 K gene, that are not involved in low-pH fusion and the cellular protein CD4. All chimeras were expressed in COS-1 cells, glycosylated, oligomerized,
transported to the cdl surface, showed a low-pH induced conformational change and were expressed on the cell surface at levels equivalent to wild-type G. The
transmembrane hybrids show extensive syncytia formation at levels similar to wild-type
G when induced at pH 5.6. The transmembrane-cytoplasmic tail hybrids showed reduced
levels of syncytia as compared to wild-type Gat both pH 5.6 and 5.2.
A glycosylphosphatidylinositollipid-anchored ectodomain of G (GGPI), which
lacks both the transmembrane and cytoplasmic tail ofG, was expressed in COS-1 cells.
The GGPI chimera was glycosylated, expressed on the cell surface,and oligomerized
similar to wild-type G. However the chimera was fusion negative, could not promote
lipid mixing and h~,d an altered tryptic digestion profile. A fusion negative chimera Gt12gBwas constructed by exchanging the TM of G with the equivalent domain from HSV-1 gB TM plus eight extra amino acids of the gB ectodomain. Deletion of the 11 extra gB amino acids (GgB3G) restored the fusogenic activity of this chimera. Another chimera G 10 DAF directly demonstrated that the fusion negative phenotype of GGPI, like chimera Gtii1Lll2gB, was a result of the 10 extra amino acids at the EC-TM interface. The ectodomain (EC)-transmembrane (TM) interface is highly conserved among 5 vesiculoviruses. Chimeras with a 9 amino acid insertion (GlODAF), deletion (G~9) or replacement (G~910DAF) were expressed in COS-1 cells. The expressed proteins were glycosylated, underwent a low-pH induced conformational change and were expressed on the cell surface at levels equivalent to wild type, but were fusion negative. Suggesting that both the sequence and spatial arrangement of amino acids at the EC-TM interface may affect VSV G fusion. Taken together the data suggests that the specific amino acid sequence of the transmembrane anchor of VSV G is not essential for fusion. Replacement of the TM of VSV G with equivalent domains from other viral and cellular proteins does not affect the fusion activity. The cytoplasmic tail of VSV G may form an entity alone or in conjunction with the transmembrane anchor that can regulate fusion. Another region in the ectodomain of VSV G renders the glycoprotein fusion sensitive in a cell-cell fusion assay and was characterized at the EC-TM interface.

abstract: Thesis

abstract: Master of Science (MS)


title: Stimulus determinants of the Müller-Lyer illusion and its decrement

title: Stimulus determinants of the M-L illusion and its decrement

contributor:
Newbigging, P.L.
Psychology

subject:
Müller-Lyer
perceptual learning

abstract: Five experiments, involving 456 subjects, were conducted to determine the influence of certain stimulus characteristics of the Müller-Lyer figure on the magnitude of this illusion and on the decrement of the illusion which occurs with practice. The results showed that the magnitude of the illusion is directly related to the length of the oblique lines and inversely related to the angle between the obliques and the prominence of the horizontal line. Reducing the angle between the obliques and reducing the prominence of the horizontal line caused the illusion to decrease more rapidly over a series of 100 trials. The final experiment provided evidence consistent with the interpretation that changes in attention may be responsible for the practice decrement. These results are discussed in terms of perceptual learning.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: The effect of shock intensity on discriminative escape conditioning

title: Discriminative escape conditioning

subject:
shock
discriminative escape conditioning
Yerkes-Dodson Law

abstract: This thesis was concerned with the effects of shock intensity on discriminative escape conditioning. At the lowest shock intensity there was a bimodal distribution of nonresponding animals at one mode and responders at the other mode. Optimum performance occurred at the lowest shock intensity at which 100% of the animals responded. At higher shock intensities performance deteriorated. An attempt to test the Yerkes-Dodson Law failed to yield conclusive results. Finally, it was found that shock intensity affected performance rather than learning.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)