title: The HII Regions and OB Stars of M33 and NGC 6822

contributor:
Wilson, Christine
Physics and Astronomy

subject:
Astrophysics and Astronomy
Physics
Astrophysics and Astronomy

abstract:
We have used Hα and photometric data for two morphologically distinct Local Group galaxies, the spiral M33 and dwarf irregular NGC 6822, to study the distribution of the luminous blue O and B (OB) stars and HII regions in the galaxies as well as to determine whether individual regions of the galaxies are separately and/or collectively in a state of ionization balance. In the case of M33, we have concentrated on the inner 1 kpc region of the galaxy. Using the Hα data, three distinct ionized gas environments (bright, halo and field) defined by the surface brightness of the Hα emission have been identified. We find that ~50% of OB stars are located in the field, so that 1/2 of the lifetime of OB stars must be spent outside recognizable HII regions. This result suggests that if OB stars escape from bright HII regions by destroying their parent molecular clouds, then molecular cloud lifetimes after forming OB stars could be as low as ~5x10⁶ yrs or 1/2 the typical lifetime of OB stars. We show that a possible origin for the large field OB population is that they were born in and subsequently percolated out of the ~10³ giant molecular clouds with masses ≳10₃M⨀ predicted to exist within the inner kpc of the galaxy. Using UBV photometry and stellar ionization models, we predict Hα fiuxes in the bright, halo and field regions and compare them to those observed to find that predicted fluxes are a factor of ~3-7 greater than observed so that the three ionized gas environments, separately as well as collectively, are not in ionization balance. Furthermore, the most substantial loss of ionizing photons appears to he taking place in the field. We find that observed and predicted Hα luminosities are in best agreement when Case A recombination is assumed in the field. Our findings suggest that star formation rates obtained from Hα luminosities must underestimate the true star formation rate within the inner region of M33. A similar analysis of an individual, isolated region with bright and halo Hα emission has produced results that are comparable to those found on the larger scale: the isolated region, as a whole, is also not in ionization balance.

In the case of NGC 6822, four distinct components of the Hα emission (bright, halo, diffuse and field) differentiated by their surface brightnesses have been identified. We find that only 1/4 of the OB stars are found in the combined bright and halo regions, suggesting that OB stars spend roughly 3/4 of their lifetimes outside "classical" HII regions. Molecular cloud lifetimes after forming OB stars could be as low as ~1-3x10⁶ yrs or 1/4 the typical main sequence lifetimes of OB stars if OB stars escape from bright HII regions by destroying their parent clouds. Additionally, the field population of OB stars cannot have originated in and percolated out of existing HII regions. Comparing the observed Hα emission with that predicted from BV photometry and stellar ionizing flux models, we find that although the bright, halo and diffuse regions are probably in a state of ionization balance, the field region, which is producing at least 6 times as much ionizing flux as is observed, is clearly not. The ionization balance results suggest that star formation rates obtained from Hα luminosities must underestimate the true star formation rate in NGC 6822 by about 50%. Comparing the results for NGC 6822 and M33 reveals that the inner kiloparsec region of M33 is in a more serious state of ionization imbalance, perhaps due to its higher surface density of blue stars. Thus the morphological class or surface density of a galaxy may be important factors in how accurately we can determine star formation rates from Hα luminosities.

Finally, we have performed optical spectroscopy of luminous blue stars in both NGC 6822 and M33 using respectively, the 4-m CTIO telescope plus ARGUS spectrograph and the 4-m Mayall telescope at KPNO plus HYDRA spectrograph. Due to the limited S/N ratio of the data, we have been able to classify only ~50% of the stars observed in NGC 6822 and ~40% of the stars observed in M33. Out of the 37 NGC 6822 and 15 M33 stars with classifiable spectra respectively 28 and 11 potential OB stars have been identified. We have used the NGC 6822 spectra to gauge the reliability of the principle stellar ionization model used for the ionization balance calculations in both galaxies.

abstract: Doctor of Philosophy (PhD)


title: A Mass Spectrometric Study of Organic Ions and Neutrals Using (Muttiple) Collision Experiments

contributor:
Terlouw, Johan K.
Chemistry

subject: Chemistry Chemistry

abstract: The unimolecular chemistry of selected organic (radical) cations has been studied by mass spectrometry based experiments (metastable ion (MI), collisional activation (CA), collision-induced dissociative ionization (CIDI) and neutralization-reionization (NR) mass spectrometry as well as multiple collision experiments (e.g. CA/CA and NR/CA) and appearance energy (AE) measurements) and ²H, ¹³C, ¹⁵N and ¹⁸O isotope labelling experiments in conjunction with ab initio molecular orbital computations. Hydrogen-bridged (radical) cations, ion-molecule complexes and distonic ions are interesting species, partly because their neutral counterparts are usually unknown but, mostly because of their significance as key intermediates in the unimolecular dissociation reactions of gas phase ions. These types of species were found to play vital roles in the unimolecular chemistry of carbamate radical cations, RN(H)COOCH₃⁺ {R = H, CH₃}. When R=H, the metastable molecular ions dissociate to two sets of products, H₂N-CH-OH+HCO˙ and [H₂C=O�H�NH₂]⁺˙+CO, with the first steps of both reactions being: H₂NCOOCH₃⁺˙→H₂N-C(OH)OCH₂⁺˙ (distonic ion)→ [H₂N-C=O�H�C=CH₂]⁺˙ (hydrogen-bridged ion). Although it does not participate in this chemistry, the imidic acid (iminol) ion, H-N=C(OH)-OCH₃⁺˙, is also stable. However, attempts to generate it led instead to the more stable, but difficult to characterize, distonic ion. The surprising loss of a methyl radical from metastable N-methyl-O-methyl carbamate radical cations CH₃N(H)COOCH₃⁺˙, is proposed to involve equilibration with two distonic isomers, CH₃N(H)-⁺C(OH)OCH₂˙ and CH₂=⁺N(H)-˙C(OH)OCH₃, the latter serving as the immediate precursor to the products: ˙CH₃ and the N-carboxyiminium ion, CH₂=N(H)-COOH⁺. The heats of formation of the molecular ion and the product ion were estimated by additivity methods. A CA/CA experiment (CH₃N(H)COOCH₃⁺˙ → CH₃NHCOH˙⁺ → HNCOH⁺) was used to generate and characterize the elusive isoformylaminylium ion. The thermodynamic and kinetic stabilities of CH₅N₂⁺ isomers have been re-evaluated in light of the results obtained from high level ab initio MO calculations and (metastable) AE measurements. NR experiments showed that the neutral CH₂=NH-NH₂˙ is a stable species but the majority of neutralized CH₂=NH-NH₂⁺ ions dissociate into CH₂=NH and NH₂⁺, a finding that is rationalized in light of the different computed geometries of the ion and radical. Mechanisms are proposed for the metastable dissociation reactions of CH₅N₂⁺ ions to HCNH⁺ + NH₃ and to HC=N + NH₄⁺, the latter rationalized in terms of a dissociating [HC=N�NH₄]⁺ ion-dipole complex. A mechanism for the spontaneous deacelylation of N-acetylmethyliminium ions CH₃C(=O)・N(H)=CH₂⁺ to CH₂NH₂⁺ + CH₂=C=O was proposed. The role of the hydrogen-bridged complex [O=C=CH₂�H�N(H)=CH₂]⁺ is discussed with emphasis placed on the observation of large isotope effects and exceedingly small translational energy releases as indications of the intermediacy of such ion-molecule complexes. Several other isomeric C₃H₆NO⁺ ions, which were briefly examined and characterized, are also discussed. The second part of the thesis focusses on the generation and identification of elusive radicals and molecules by neutralization-reionization mass spectrometry and multiple collision experiments. It begins with a study of three isomeric [C₂NO] cations that were characterized by (multiple) collision experiments. NR and CIDI experiments were used to demonstrate the existence of the corresponding radicals NCCO˙, CNCO˙ and CCNO˙ as stable species in the gas phase. Appropriate dissociative ionizations were used to produce diamino- and dihydroxy-carbene radical cations. Reduction of the ionized carbenes by single-electron transfer in NR experiments yielded "survivor" signals but collision experiments on the reionized neutrals (NR/CA) were required to unambiguously estabIish that the prototype carbenes, H₂N-Ċ-NH₂ and HO-Ċ-OH, were generated as stable gaseous species, distinct from their isomers formamidine, H-N=C(H)NH₂ and formic acid, O=C(H)OH. Similarly, a combination of NR mass spectrometry and (multiple) collision experiments on D and ¹⁵N labelled isotopomers made it possible to assign structures to the prototype imidic acid, formimidic acid, H-N=C(H)-OH, and aminohydroxycarbene. H₂N-Ċ-OH, both isomeric with formamide. The ionic precursors H-N=C(H)-OH˙⁺ and H₂N-C-OH˙⁺ were produced by appropriate dissociative ionizations and direct ionization of formamide yielded H₂N-CHO˙⁺. NR experiments produced intense "survivor" signals. By combining information contained in CA mass spectra of the "survivor" ions with that from labelling experiments, the existence of formimidic acid and aminohydroxycarbene as stable molecules in the gas phase was established. Using the same experimental methodology, the existence of the imidic acid CH₃-N=C(H)-OH and the carbene CH₃-N(H)-Ċ-OH was also established.

abstract: Doctor of Philosophy (PhD)


title: Motion and Force Control of Flexible Joint Robot Manipulators

contributor:
ElMaraghy, Hoda A.
Mechanical Engineering

subject:
Mechanical Engineering
Mechanical Engineering

abstract:
Excitation of lightly damped drive system resonances severely limits the performance of most current robotic manipulators. Also, many industrial applications require the control of the contact forces in order to execute contact tasks properly. This dissertation discusses the development and experimental verification of advanced high performance control algorithms in order to control the position and contact force of nonlinear manipulators with flexibilities which reside in the drive systems. An experimental two-link planar manipulator has been designed and constructed to test the control algorithms. The developed manipulator exhibits damped drive system resonances and highly nonlinear and coupled dynamics.

Several techniques for controlling the position and force of flexible joint robot manipulators are developed and evaluated. A collocated Proportional-Derivative controller is implemented to demonstrate the limitation of such a controller which is commonly used for industrial robots. Then, a fourth order feedback linearizable model is constructed and analyzed. A feedback linearization controller is designed, simulated and implemented in the joint space as a preliminary investigation of the feedback linearization performance. Results proved a tracking performance superior to that of the PD controller and support applying feedback techniques for position and force control.

Two model-based position and force control approaches based on feedback linearization concept are developed, simulated and implemented. The dynamic hybrid controller deals with the contact with rigid environments while the impedance control deals with performing free and/or contact with compliant environment motions. The results indicate excellent performance in tracking the position and regulating the contact force. These two approaches serve as basic structure for the design of robust and adaptive controllers.

A robust sliding mode controller is designed, simulated and implemented to maintain the model-based tracking performance in the presence of payload variations and other parametric uncertainty. The problem is formulated by using the feedback linearizable model and the constraint imposed by the contact environment, to characterize the disturbance caused by parametric uncertainty in the system. In addition, the effect of parametric uncertainty on computing the unmeasured state elements is included in the analysis and the design of the robust controller. Results indicate that the controller obtains an excellent tracking performance in the presence of parametric uncertainty. This controller solves the problem of the necessity of the exact state of the feedback linearizable system for feedback. In addition, a specific relation between the uncertainty bounds and the achievable accuracy is derived. Another alternative to deal with parametric uncertainty is an adaptive cascade controller which is developed, simulated and implemented. It consists of a direct adaptive controller for the rigid dynamics and a Model Reference Adaptive Controller (MRAC) for the flexible dynamics. Results indicate good force tracking with slow position response. The cascade approach requires extremely fast actuator to achieve the feedback linearization results. A robust sliding mode observer is developed in order to estimate the unmeasured state elements of the feedback linearizable system in case of parametric uncertainty. This observer is useful for the successful application of adaptive feedback linearization algorithms. An adaptive feedback linearization control algorithm combined with the sliding mode observer is developed and simulated. The formulation enables designing adaptive laws using the original system state and the angular accelerations instead of the state of the feedback linearizable system and characterizing the stability of the overall system. The simulation results show the ability of the control algorithm to achieve position and force tracking by robust estimation of the state vector and updating of the robot parameters.

abstract: Doctor of Philosophy (PhD)


title: Spatial Concentration of Community Mental Health Facilities

contributor:
Taylor, S.M.
Geography

subject: Geography Geography

abstract:
This thesis examines the factors contributing to the spatial distribution of community mental health facilities. It is a readily observable phenomenon that these facilities are concentrated within easily identifiable areas of the central city, yet the factors contributing to this pattern are not as easily discerned. This thesis argues that the ghettoisation of facilities is the product of a complex interaction of social and political forces that are intrinsically associated with the many dimensions of locational conflict. The nature of community response and the exercise of political power are key elements of this process. Both of these elements exhibit distinct socio-spatial characteristics. In light of this, the research goals of this thesis sought to identify whether systematic relationships exist between the concentration of facilities and community attitudinal and socio-environmental characteristics.

Metropolitan Toronto was the study area for this thesis. Socio-environmental data were collected measuring the major social and physical characteristics of the neighbourhoods under examination. Attitudinal data were taken from a major survey (1090 people) of attitudes toward the mentally ill and mental health facilities conduced in Toronto. The relationships of these variables to facility concentration were tested individually and in combination.

The results of the analysis indicated that the socio-environmental variables were more strongly related to facility concentration than the attitudinal variables. With respect to both sets of characteristics, areas of low concentration were most similar to one another and most different from areas of high concentration.

abstract: Master of Arts (MA)


title: Reaching into Cluttered Visual Environments: Evidence for Action Representations of Non-target Objects

contributor:
Milliken, B.
Psychology

subject: Psychology Psychology

abstract: Among the most important behavioural abilities possessed by humans and other animals is the ability to act selectively in complex sensory environments that afford a large number of potential actions. A common example of such selective action used by experimental psychologists is picking a ripe (red) apple among unripe (non-red) apples. In the laboratory, this selection problem is usually examined using colour visual search tasks, in which subjects have to make a spatially-arbitrary response when they detect a red target among yellow non-targets. Typically selective processes handle such a selection problem very efficiently - measured by no increase in response time when non-targets are present. But such search tasks are poor analogues of the apple picking problem, because in order to pick the red apple one must direct a reaching response to its spatial location. The experiments in this thesis instead used a selective reaching task in which subjects responded to a red target, in the presence of a yellow non-target, by reaching to its location. In the selective reaching task, unlike in the search task, selective processes do not handle the selection problem with optimal efficiency - measured by an increase in response time when non-targets are present (i.e., interference). The experiments in the thesis were designed to show that this suboptimal selection efficiency was related to the fact that reaching responses were used. The hypothesis was informed by physiological evidence that the visuomotor information and colour information are processed by parallel pathways in the visual system. The need for visuomotor processing leading to reaching distinguishes the selective reaching task from the search task. The experiments provided support for the hypothesis that this visuomotor processing led to the concurrent activation of subovert reaching responses associated with the target and non-target, creating a response competition. The results have implications for theories of selection that purportedly apply to real-world situations such as picking a ripe among unripe apples, but that do not take into account the act of picking the apple itself. Applications of the results to real-world situations in which people reach for the wrong object in multiple-object visual displays are also discussed.

abstract: Doctor of Philosophy (PhD)


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

contributor:
MacDonald, G.M.
Geography

subject: Geography Geography

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 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 cap provide a proxy climate record; 2) annual area burned in the boreal forest varies in response to climate changes: 3) boreal forest 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 or 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 free 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 these 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 bureal 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: Doctor of Philosophy (PhD)


title: An Integrated Scheduling Approach for Discrete Manufacturing Systems

abstract:
Efficient scheduling in discrete manufacturing environment can improve productivity through reduced work-in-progress and finished good inventories. This research examined the feasibility and advantages of using genetic algorithms in manufacturing scheduling. All literature to date indicate that there is a need for better scheduling algorithms which can provide better and faster solutions. This thesis focuses on the improvement of the scheduling performance through: a) the application of genetic algorithms to the schedule optimization problem, b) the consideration of batch splitting and c) dynamic scheduling.

First, genetic algorithms are developed for two types of scheduling situations: a) scheduling in the presence of single process plans without any routing flexibility and b) scheduling where routing flexibility and multiple process plans exist. Analytical techniques and heuristics-based methods have been developed by other researchers to solve such scheduling problems which are useful for limited size problems. Since the schedule population size is fixed in genetic algorithms, there is a tremendous reduction in the memory requirements. In every generation bad schedules are replaced by better ones. Also, since genetic algorithms performs a multi-point search at a time, they are relatively faster than other techniques used for scheduling which are usually based on single point search. Genetic algorithms models were formulated and tested using nineteen example problems for both flexible and fixed routing scenarios. Numerical results show that the genetic algorithms approach perform significantly better than other approaches both in terms of funding the optimal/near optimal solution and the computation time. The saving in computation time was up to 50% in some cases. Because of the vast number of schedules available in the case of multiple process plans, dispatching rules have been employed in the genetic algorithms to obtain a satisfactory schedule. It is often observed that in the case of alternate routings and while using dispatching rules, researchers tended to use a single job in each order which is rarely the case in practice. In this thesis, both alternate routings and order sizes greater than one are simultaneously considered along with dispatching rules while scheduling with genetic algorithms. Twelve different dispatching rules and seven performance criteria are used and the performance of each rule has been studied extensively with respect to each of the performance criteria.

Second, three new batch splitting policies were introduced in this research to split the batches into smaller sub-batches. A process plan-based method was developed, where the information available from the process plans is used for batch splitting. This is different from other batching policies where batching is done based on inventory models from queueing theory for which cost function consisting of ordering, inventory holding and work-in-process carrying costs are required. The new batch splitting policies were compared with existing ones and the results show that in several cases the newly developed policies performed significantly better than existing ones. The improvement in the performance was observed to be in the range of 35% to 45%.

Next, the dynamic scheduling aspects are considered and rescheduling algorithms were developed for four kinds of uncertainties. These include unexpected machine breakdown, rush order arrival, order cancellation and increased order priority. These algorithms reschedule only interrupted tasks, hence focusing on local rescheduling. These algorithms were tested using three different performance criteria namely, mean flow time, mean tardiness, and average machine utilization. The developed rescheduling algorithms proved successful in dealing with the shop floor uncertainties and the results indicate that the proposed algorithms are effective and could easily be used to dynamically schedule the manufacturing systems in the presence of disturbances.

Finally, as part of the system implementation, a user interface has been developed in 'C' to input required scheduling data used for schedule optimization. The scheduler outputs a list of several good schedules. These schedules are then analyzed by the output analyzer which outputs a list of different performance criteria values, machine utilizations, ready and completion times of each order and the Gantt chart of the best schedule.

abstract: Doctor of Philosophy (PhD)


title: Robust Design and Experimental Optimization Approaches for Concurrent Design

contributor:
ElMaraghy, H.A.
Mechanical Engineering

abstract:
The increase in quality requirements demands efficient integration of design and manufacturing concerns. This thesis develops a robust design procedure and a novel experimental optimization approach for considering manufacturing tolerances (dimensional and geometric) from both design and manufacturing perspectives. Manufacturing capabilities prohibit the tight control of variations in geometry, dimensions and positions in system components. Two formulations are used where manufacturing tolerances are considered as: i) control variables and ii) noise variables beyond the designer's control. Results indicate the superiority of the developed procedure to detect a design region where system response is robust to sources of variations. Moreover, the procedure overcomes the shortcoming of on-line programming to deal with multi-variable problems and multi-level noisy space. The procedure is applied efficiently and successfully to typical product and process design.

A statistical optimization procedure is developed, implemented and tested to deal with situations where there is no explicit objective functions. The procedure results in a robust design by proper assignment of nominal and tolerance values. Standard matrix decomposition methods and orthogonal search allow obtaining functionally independent designs. The developed procedure and techniques change design specifications from 'acceptable within limits' to 'close-to-target value'. This technique has the advantage of reducing the tolerance optimization problem and minimizing manufacturing costs.

The concept of orthogonal arrays and experimental optimization is used to develop an algorithm for unconstrained and constrained discrete problems. The algorithm employs specially coded designs to form combinatoric search in one and two domains. As a search in one domain, the algorithm uses data from Coordinate Measuring Machines (CMMs) and evaluates the tolerance zones of engineering features such as straightness and roundness (2-Dimensional) and flatness, cylindricity and sphericity (3-Dimensional). The problem of least cost tolerance allocation and optimum process selection is formulated as a discrete optimization problem. The problem is viewed as a search in two domains: the first is tolerance allocation that satisfies the assembly functional requirement; the second is process-selection such that the production cost is minimal. This formulation is based on coupling an inner array (tolerance selection domain) and an outer array (process selection domain). The choice of different structures of orthogonal arrays has a tremendous impact on the resulting minimum production cost and optimum tolerances. Each orthogonal array can be represented by a search graph which can aid the designer in the initial assignment phase. The developed algorithm overcomes one major shortcoming of almost all existing search techniques namely the need for excessive number of function evaluations and provides near-to-global optimum consistently with high reliability.

Finally, the experimental design techniques are used to deal with the problem of linear and nonlinear tolerance analysis of mechanical assemblies. The principal goal was to find a substitute for the expensive Monte Carlo-based simulation technique. Results illustrate the successful application of different orthogonal arrays in yielding a comparable system moments in small finite number of experiments with a sample of 10,000 (linear assembly) and 1,000 (nonlinear assembly).

This dissertation surveys the literature and offers solutions to various design and manufacturing problems. In fact, it proposes unique tools and techniques to tackle problems such as robust product and process design, nominal and tolerance value assignment, form tolerance evaluation, discrete optimization and linear and nonlinear tolerance analysis.

abstract: Doctor of Philosophy (PhD)


title: The Myth of Laura Secord in Nineteenth-Century Artistic (Re)presentations to Twentieth-Century Popular Culture

contributor:
York, Lorraine
English

subject:
English Language and Literature
English Language and Literature

abstract: This investigation explores the mythification of Laura Secord based on an interdisplinary fusing of Victor Turner's ritual anthropology with literary approaches emphasizing semiotic responses to art. The theoretical framework is explored by an analysis of the artistic works signaling the myth's developmental phases: Sarah Anne Curzon' s Laura Secord: The Heroine of 1812 (1887), Lereine Ballantyne's Heroes of History (192?), Alexander Maitland Stephen's Laura Secord (1929), Merrill Denison's Laura Secord (1931), and other minor works. In addition, Frank P. O'Connor's appropriation of Laura Secord for his Candy Company is considered. The study's central premise, posed in the preface and introduction, is that the various portrayals of Laura Secord form a mythic tradition which functions as a reflector of communal interests and concerns. Chapter One provides an historic and artistic overview of this premise, narrative's rite de passage toward public recognition. Chapters Two, Three and Four continue this exploration in relation to specific works and demonstrate that society's active participation in the myth-making process reflects its own communal development. The interdisciplinary framework investigated here contributes to an understanding of myth as an indicator of social, cultural and political change, as well as communally empowering.

abstract: Doctor of Philosophy (PhD)


title: Mixed Storm and Tidal Facies Successions of Mixed Grain Size, Shallow Marine Sediment in Foreland Basin Units: the Albian, Viking Formation, Townships 45 to 54, Ranges 10W4 to 21W4, Alberta, Canada

contributor:
Walker, R.G.
Geology

subject: Geology Geology

abstract:
The siliciclastic, Lower Cretaceous, Albian, Viking Formation was deposited in the foreland basin of eastern central Alberta. Sediments in the area studied were formerly interpreted as "offshore bars" or lowstand shorefaces. It is shown in the first extensive, detailed core and well log study o the basinal portion of the formation that the sediments are sheet sand deposits laid down by a mixture of storm and tidal flows. The sediments divide into twenty facies ranging from grey shale to conglomerate but mostly consisting of bioturbated or crossbedded muddy sandstones and siltstones.

The facies assemble into six units: Mu, Epsilon, Delta, Gamma, Beta and Alpha, in stratigraphically ascending order. Unit boundaries are at points of rapid facies changes. There are no extensive discontinuities. Units Epsilon, Delta and Gamma are gradationally coarsening upward from basal bioturbated marine siltstones to heterolithic, sometimes glauconitic crossbedded or bioturbated marine sandstones. Unit Beta is consistently line grained showing a slight coarsening upwards from bioturbated siltstones to crossbedded siltstones.

Datum to unit boundary isopachs and unit isopachs indicate post unit Mu, westward subsidence leading to accommodation of units Epsilon through Gamma. During deposition of units AIpha and Beta, subsidence returned to a more even basinwide pattern.

Unit isopachs of Epsilon, Delta and Gamma reveal prograding and aggrading "shoreface" wedges in the southwest of the study region. Details of the isopachs reflect fingers of irregular sand sheets. The facies of these sand sheets are interpreted to be finally deposited by storm enhanced flows in a tidally dominated basin. Unit Beta provides evidence for a facies summary of a distal storm/wave dominated shallow shelf. In all cases, lateral facies changes appear random.

The units do not fit common sea level curve interpretations because the onset of transgression is located within the upper, coarser portion of the units rather than at the unit boundaries. Neither the units nor the formation can be correlated precisely to existing sea level curves. Combined with the evidence for tectonic control of unit geometries, this suggests periodic activity such as thrust loading of the cordillera west may control unit development in foreland basins.

abstract: Doctor of Philosophy (PhD)


title: Boundary Layer Flow Fields around Rotating Spheres

contributor:
Round, G.F.
Mechanical Engineering

abstract: The boundary layer equations governing the conservation of mass and momentum and the corresponding boundary conditions are derived, using spherical coordinates for flow past a rotating sphere. A finite-volume-based numerical scheme using structured orthogonal body-fitted grids was used to examine potential and vortex flow around a stationary sphere and flow fields around rotating spheres whose axes are parallel and perpendicular to the free stream direction. Some parametric studies were conducted. The results are presented in graphical form for flow visualization. Experiments for the case of the rotational axis being perpendicular to the free stream were designed and data generated using a triple-sensor probe. It has found that the numerical results agreed reasonably well with experimental results within experimental uncertainty. The comparisons were not completed over whole flow field due to the limitations in the experimental conditions.

abstract: Doctor of Philosophy (PhD)


title: The Effects of Multiple Extrusion Passes During the Recyling of High Density Polyethylene

contributor:
Latto, B.
Vlachopoulos, J.
Mechanical Engineering

abstract:
Plastics recycling has received significant attention within the past decade. Positive or negative, the attention has provided an impetus for the plastics industry to advance recycling technology. High density polyethylene blow molding resins have been identified as a primary material for solid waste minimization and recycling. This thesis is concerned with the effects of multiple extrusion passes on the processing and product application properties of high density polyethylene blow moulding resins. The objective is to provide a comprehensive analysis on the system of properties as they are affected by multiple extrusion passes.

A justification for this present work is provided by a description of the current state of plastics recycling in terms of the history, legislation and technology. The role of political and global market pressures, relative to legislative initiatives such as the Green Dot program in Germany, the 3 R's legislation in Ontario, the content legislation in California and the decision to ban products such as polystyrene foam clamshell packaging, and the impact of these events on the research initiatives in plastics recycling is discussed.

An experimental study into the effect of multiple extrusion cycles on the properties of a virgin homopolymer, virgin copolymer, natural post consumer and mixed colour post consumer blow moulding resin was conducted. Rheological properties such as shear and elongational viscosity and elastic modulus were studied in the context of changes experienced during recycling. The G' - Gil (elastic storage and loss modulus) crossover point was used to measure relative changes in the polydispersity index and molecular weight distribution. It is also shown how parameters such as the Bagley correction factor, extrudate swell and sag are sensitive to the effect of multiple extrusion passes. Strength properties such as tensile strength and environmental stress crack resistance were measured. A rationale for the significant decrease in the environmental stress crack resistance of the virgin copolymer resin is presented. The results are analyzed in terms of known degradation mechanisms such as chain scission and cross-linking, and their relationship to the Phillips and Ziegler-Natta catalyst systems. Principal component analysis, a multivariate statistical technique, was applied to this plastics recycling study to provide data based support in the identification of those responses, within a system of correlated responses, which are most affected by multiple extrusion passes.

abstract: Doctor of Philosophy (PhD)


title: Multimerin, a Platelet and Endothelial Cell Protein

contributor:
Kelton, John G.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract:
p-155 is a soluble platelet protein, with a reduced subunit mobility of 155 kDa, that was first identified using a monoclonal antibody raised against platelets. This thesis describes the identification and characterization of p-155, including its structure, biosynthesis, cells of origin, and cDNA sequence. Studies of the native p-155 protein indicated that it is comprised of variably sized, disulfide linked multimers of p-155 subunits, ranging in size from a 400 kDa trimer to large multimers, many millions of daltons in size. Based on its massive, multimeric structure, the native p-155 protein was designated as multimerin. Comparisons with other multimeric proteins found in platelets indicated that multimerin is a novel protein and also one of the largest proteins stored in platelets. In addition to platelets, multimerin was also found in endothelial cells. Biosynthetic metabolic labeling studies indicated that multimerin is synthesized by Dami cells (a megakaryocytic cell line), and by endothelial cells. Multimerin is a highly glycosylated protein with complex, N-linked carbohydrate accounting for 1/3 of its molecular mass. Cleveland mapping studies were used to investigate the relationship between the different sized multimerin subunits found in platelets and Dami cells. These studies demonstrated peptide homology, indicating that p-155 and p-170 (a larger but less abundant multimerin subunit found in platelets) originate from p-196, the multimerin precursor protein identified in metabolic labeling studies.

Multimerin antibodies were used to screen expression human endothelial cell libraries for multimerin cDNA clones and the most 5' cDNA clone was used to rescreen the library for complete 5' sequence. The complete cDNA sequence for multimerin was then determined. The multimerin cDNA sequence encodes a hydrophilic protein of 1228 amino acids with RGDS, EGF-like, partial EGF-like, and putative coiled-coil domains. In addition, the C-terminal region of multimerin resembles the globular head domain of complement Clq and collagens type VIII and X. These studies establish multimerin as a unique, multimeric platelet and endothelial cell protein. The massive size, GDS motif, and repeating structure of multimerin suggest a possible role for this protein in adhesion.

abstract: Doctor of Philosophy (PhD)


title: Dissociating Recollection and Familiarity in Recognition Memory

contributor:
Jacoby, Larry L.
Psychology

subject: Psychology Psychology

abstract: The processes underlying recognition memory were examined using the process dissociation procedure (Jacoby, 1991). Recognition judgements based on recollection were found to differ in several fundamental ways from those based on familiarity. Increasing list length interfered with recollection but left familiarity intact. Response time distributions and the results of a response signal procedure showed that familiarity was faster as a basis for recognition judgements than was recollection. The analyses of receiver operating characteristics (ROCs) showed that recollection led to high confidence memory judgements that remained relatively constant as response criterion was varied. Familiarity, on the other and, increased gradually as response criterion was relaxed. Results support a dual-process model of recognition in which a discrete recollection process operates independently of a continuous familiarity process.

abstract: Doctor of Philosophy (PhD)


title: Hedonics of Taste-Odor Mixtures: A Study of Flavor Perception

contributor:
Weingarten, Harvey P.
Psychology

subject: Psychology Psychology

abstract:
Most research done on taste and smell has examined the two systems in isolation. This is unfortunate since it is the combination of taste and smell that determines flavor, perhaps the most salient characteristic of food for humans. Furthermore, assessment of flavor pleasantness is integral to food choice and intake. Yet, despite the importance of the hedonic dimension of flavor, most empirical studies of flavor have focused on the intensity of taste-odor mixtures, not their hedonic value. Thus, the experiments that comprise this dissertation focused on the pleasantness of taste-odor mixtures.

Three food odors (chocolate, raspberry, and popcorn) at five concentrations were utilized as stimuli. Experiment 1 replicated the psychophysical functions that have been reported in the literature relating stimulus strength, perceived intensity, and perceived pleasantness with these three odors. Experiments 2 and 3 demonstrated that a negative taste experienced concomitantly with odor reduces odor pleasantness ratings. Experiment 4 established that it is unlikely that this effect results from a general negative affective state since an aversive non-gustatory stimulus did not produce a similar reduction in odor pleasantness.

Subjects in Experiments 1 through 4 were required to report odor pleasantness. However, in these studies it was not clear whether subjects were reporting a downward shift in odor hedonics, a negative hedonic response to taste, or their hedonic response to the taste-odor mixture. Experiment 5 required subjects to be analytical about their hedonic response to taste-odor mixtures. They were instructed to report their independent hedonic response to the odor, taste, and overall sensation. Experiment 5 demonstrated that when subjects are explicitly required to be analytical about the hedonic experience of flavor, they can differentiate between a taste they do not like an odor that is neutral or pleasant to them. However, when not instructed to be analytical, subjects tend to fuse the components into a whole percept or "gestalt."

Metabolic changes modulate the pleasantness of sensation, a phenomenon known as alliesthesia. It is clear that hunger increases the pleasantness of sweet taste relative to the sated state, but the effect of metabolic state on odor hedonics is unclear. Thus, in Experiment 6, I first replicated alliesthesia for sweet taste and demonstrated that aversive tastes are not made more pleasant by hunger. More importantly, though, Experiment 6 showed a clear odor alliesthesia effect; that is, a reduction of odor pleasantness when subjects are full relative to hungry.

It has been suggested that odor hedonics are more labile than taste hedonics. Since no studies have empirically compared the modulation of taste-odor mixtures by hunger and satiety, it is not known whether alliesthesia is greater for the taste or odor component of flavor. Experiment 7 required subjects to be analytical about their hedonic experience of taste-odor mixtures when hungry and full. General alliesthesia was observed, that is, hedonic ratings of all stimuli were lower in the hungry state relative to the sated state. The alliesthesia effect did not depend on whether subjects rated odor alone, taste alone, or a taste-odor mixture. Thus. no distinction could be made between taste or smell in terms of degree of hedonic modulation by metabolic state.

The main goal of these experiments was to explore the hedonics of taste-odor mixtures in humans. These examinations increase our understanding of the chemical senses in general and may be particularly pertinent to understanding the relationship between food hedonics and ingestive behavior. Future work should concentrate on whether food hedonics as studied psychophysically in the manner of the experiments comprising this dissertation predict food preferences or intake. Additionally, the influence of cognitive factors (e.g. identification of the odor as food related) on the hedonics of taste-odor mixtures should be determined.

abstract: Doctor of Philosophy (PhD)


title: Algorithms for Multiple Sequences Alignment, Comparison of Trees, and Steiner Trees

contributor:
Jiang, Tao
Electrical and Computer Engineering

subject:
Electrical and Computer Engineering
Electrical and Computer Engineering

abstract:
Comparison of sequences and trees is an essential problem in computational biology. In this thesis, we investigate some algorithmic problems in sequence and tree comparison. Theoretical issues such as computational complexity, the efficiency of algorithms, and the performance of approximation algorithms are stressed.

The most popular approach for comparing a set of sequences is multiple sequence alignment. We show that two popular variants of multiple sequence alignment, multiple alignment with SP-score and tree alignment, are NP-complete. We also design a polynomial time approximation scheme (PTAS) for tree alignment, which is believed to be the first PTAS in computational biology.

Tree comparison has applications in the study of RNA secondary structures and evolutionary trees. We propose the notion of alignment of trees as a new method for comparing RNA secondary structure trees and give an efficient algorithm for computing the optimal alignment of such trees. Several other methods for comparing evolutionary trees are also considered.

Steiner trees have been studied extensively in the literature, and are closely related to tree alignment. We also design a PTAS for some planar Steiner tree problems.

abstract: Doctor of Philosophy (PhD)


title: Stratigraphy, Taphonomy and Paleoecology of the Upper Cretaceous Bearpaw Formation in Southern Alberta

contributor:
Westermann, G.E.G.
Geology

subject: Geology Geology

abstract:
The Upper Cretaceous Bearpaw Formation of southern Alberta was deposited in a western embayment of the Western Interior Seaway of North America. The formation records nearshore deposition in wave-dominated to fluvial-influenced settings and offshore deposition in storm-affected, shallow to deep basinal settings. Temporal variations in lithofacies are linked to third-order sea-level fluctuations, superimposed on the second-order, transgressive-regressive Bearpaw cycle.

Faunal composition of benthic faunal assemblages was largely dictated by benthic oxygen levels, and substrate characteristics. Deep-infaunal, suspension-feeding benthos were restricted to well-oxygenated, sand-dominated shoreface and shallow-offshore environments. Dysaerobic, mud-dominated offshore environments hosted a scattered background fauna of deposit-feeding bivalves, large epifaunal suspension-feeding bivalves, and decapod crustaceans. Short-lived episodes of improved oxygenation permitted the periodic establishment of opportunistic benthic communities. These "event communities" were generally typified by dense. monospecific aggregates of epifaunal and shallow infaunal suspension-feeding taxa, although more diverse assemblages containing deposit-feeders and carnivores/scavengers were occasionally established.

Morphofunctional analyses, and vertical and spatial distribution of ammonoid shells indicate that the Bearpaw ammonoids had diverse habitats. Most significantly, maximum habitat depths, inferred from septal strength estimates reveal a distinct depth zonation of ammonoid taxa. Adult Jeletzkytes, Hoploscaphites and Baculites ovatus were demersal, chiefly confined to the lower water column. Adults of the Baculites compressus group, and to a lesser extent, Rhaboceras lived at mid-water depths. Placenticeras is interpreted to have been nektic, living in the uppermost levels of the water column. Juvenile scaphitids and baculitids were strictly demersal and were particularly sensitive to oxygen fluctuations near the sea floor. Anomalously low δ¹⁸O signatures in Placenticeras nacre provides evidence of brackish conditions in the upper water column. Oxygen depletion in the lower to middle water column produced variations in the faunal composition of ammonite assemblages and differences in the spatial and temporal distribution of individual taxa.

The origin of shell-rich concretions in offshore facies is linked to preferred calcium carbonate precipitation around shell-filled, storm-related scours. Local scours were formed due to augmented sea floor erosion around topographic irregularities, such as benthic community clusters. Variations in the faunal composition and biostratinomic characteristics of the shell-rich scour fills reflect differences in storm energy and modes of scour initiation. Similarly, exceptional preservation of the lobster Palaeonephrops is linked to preferential phosphate precipitation in the vicinity of phosphate-bearing decapod cuticle. Rapid burial of living lobsters was facilitated by the collapse of their unlined burrows, whereas the rapid burial of moults was restricted to periods of volcanic ashfall.

abstract: Doctor of Philosophy (PhD)


title: Double Layer interaction Model and Particle Concentration Effect in Water

contributor:
Kramer, J.R.
Biochemistry

subject: Biochemistry Biochemistry

abstract:
The observation that an increase in particle concentrartion increases the solute concentration has been noted by a number of investigators. This phenomenon is very important to re-suspension of particles and contaminant release and diagenesis. Various reasons for this effect have been proposed. This study investigates the role of repulsive forces acting among particles when they are close to one another (e.g. double layers overlap).

The approach was to assess all possible forces theoretically. The only significant long range force is the columbic force which is shown to increase the solute concentration. A double layer interaction (DLI) model was developed based on this theory. The predicted ionic strength effect is the same as has been observed experimentally. The model gives limits for the particle concentration effect.

In other experiments, a Couette device was also constructed to examine the impact of inter-particle collision or adsorption.

Environmental implications of the particle concentration effect are that desorption (of contaminants) can occur up to 30% for clay sized particles in fresh water (ionic strength less that 0.1 m/l).

abstract: Doctor of Philosophy (PhD)


title: Computation of Snowmelt at a High Arctic Site

contributor:
Woo, M.K.
Geography

subject: Geography Geography

abstract:
In 1977, snowmelt was studied at a site near Resolute Bay, N.W.T., with additional data obtained in 1978. Using measured net radiation and computed fluxed of sensible and latent heat, the surface energy balance over snow was calculated. Field measurements of snow ablation compared fabourably with the computed values, indicating that the energy balance approach is adequate for the computation of snowmelt at a High Arctic site.

The surface energy balance was also extended to a number of slopes using data from the horizontal site. On individual clear or partly cloudy days, the difference in the surface energy balance between slopes was small and on overcast days, such differences were further minimized. Over the entire study period, computations show that there was little difference in the amount of energy received by various slopes up to 10°.

abstract: Master of Science (MS)


title: Long chain fatty acid uptake by and trafficking within 3T3-L1 adipocytes

contributor:
Gerber, G.E.
Biochemistry

subject: Biochemistry Biochemistry

abstract:
Long chain fatty acids (LCFA's) are important metabolic substrates for mammalian cells. They are utilized as energy sources, through β-oxidation, and as substrates for the synthesis of lipids, including phospholipids and triglycerides, as well as lipids involved in cellular signalling. LCFAs, themselves can also participate in a variety of crucial cell signalling cascades. Adipocytes, through the storage of LCFAs as triglycerides and the mobilization of stored LCFAs are important regulators of energy balance in mammals. A variety of pathogenic conditions involve impaired storage or utilization of LCFAs.

The involvement of LCFAs in these events involves their initial interaction with, uptake by and trafficking within cells. These processes were studied in murine 3T3-L1 cells, which differentiate from preadipocytes to adipocytes. Upon differentiation, they acquired increased levels of LCFA uptake, which was saturable, exhibiting high affinities both for oleate, a natural LCFA, and for 11-m-diazirinophenoxy-[11-³H]undecanoate, a photoreactive LCFA. This established them as a convenient cellular model in which to study LCFA uptake and trafficking. Furthermore, it established the photoreactive LCFA as an analogue of LCFAs which could prove useful for the identification and characterization of cellular LCFA binding proteins which might be involved in LCFA uptake and trafficking.

It has been proposed that cellular uptake and trafficking of LCFAs is a multi-step process involving the delivery of LCFAs to the cell surface, their movement across the plasma membrane and their delivery to intracellular sites. The involvement of each step in LCFA uptake and trafficking in 3T3-L1 adipocytes were studied. Serum albumin, the major carrier of LCFA's in plasma had a saturable, stimulatory effect on oleate uptake by 3T3-L1 adipocytes. Serum albumin which had been photo-labeled with the photoreactive LCFA, bound to 3T3-L1 adipocytes saturably. This implicated the involvement of cellular receptors for serum albumin in the delivery of LCFAs to the cell surface.

The photoreactive LCFA was also used to identify a novel 22 kDa protein as the only high affinity LCFA receptor in the plasma membrane of 3T3-L1 cells. It was localized to the caveolae fraction of the plasma membrane and was identified immunologically as caveolin, a resident component of caveolae. Caveolin was resolved by 2-dimensional polyacrylamide gel electrophoresis into at least two forms, differing in their reaction towards an antibody recognizing a stretch of amino acids found in the predicted amino-terminal sequence of caveolin. Both forms, however had similar affinities toward the photoreactive LCFA (Kd's of 373 and 388 nM). Caveolae in the plasma membrane are believed to act as sites of transport of a variety of compounds; the localization of the only high affinity, plasma membrane LCFA receptor within caveolae suggested that they may also be sites of LCFA transport or signalling events.

A 15 kDa, cytoplasmic protein was also labeled by the photoreactive LCFA. It was identified immunologically as the adipocyte lipid binding protein (ALBP), a member of the family of low molecular weight cytoplasmic fatty acid binding proteins. Its affinities for the photoreactive probe and natural LCFAs were determined by photoaffinity labeling and by ligand displacement, respectively. The labeling of ALBP by the photoreactive LCFA in intact 3T3-L1 adipocytes was dynamic. The time-dependence of its labeling revealed that the newly internalized photoreactive probe initially bound to and then became released by ALBP, consistent with a role for ALBP in the delivery of newly internalized LCFAs to sites of utilization within cells.

The labeling of ALBP by the photoreactive LCFA in intact cells was sensitive to inhibitors of different steps in LCFA uptake was also demonstrated. This confirmed that LCFA binding to ALBP occurred as an intermediate step in LCFA uptake. It also provided a means of discriminating between effects of various manipulations on early steps (upstream of LCFA binding to ALBP) and late steps (downstream of LCFA binding to ALBP) in LCFA uptake. Using this approach, the dependence of the movement of the photoreactive LCFA across the plasma membrane on ΔpH was demonstrated. This indicated that it traversed the membrane as the protonated species by diffusion across the lipid bilayer. Using this approach, α-iodopalmitate, an inhibitor of LCFA uptake originally thought to affect the movement of LCFAs across the plasma membrane, was shown to inhibit uptake by acting at a step downstream of LCFA binding to ALBP. This led to the identification of the specific target for delivery of LCFAs as the lipid droplet. This was the first in vivo demonstration of the delivery of LCFAs and of a specific target organelle for the delivery of newly internalized LCFAs by the ALBP in intact cells. It also led to the demonstration of the importance of long chain fatty acyl-CoA synthetase in LCFA uptake. This enzyme catalyzes the first step in LCFA metabolism, namely, the activation of LCFAs by conversion to their CoA thioester derivative. Its inhibition by α-iodopalmitate was shown to result in the inhibition of LCFA uptake, suggesting that the uptake process was driven by the conversion of LCFAs to their CoA thioester derivatives.

abstract: Doctor of Philosophy (PhD)


title: Finite Element Analysis of Layer Non-Uniformity in Polymer Coextrusion Flows

contributor:
Hrymak, A.N.
Vlachopoulos, J.
Chemical Engineering

subject:
Chemical Engineering
Chemical Engineering

abstract:
Coextrusion is an important polymer processing technology that consists of combining layers of different materials in their molten state to form a uniform structure. The final product has the combined properties of the individual components at a cost that is a fraction of lamination. Two basic problems have been defined in polymer coextrusion: the temporal instability of the polymer/polymer interface, and the problem of maintaining a uniform layer and thickness distribution across the die in steady state operation. This work is concerned with the latter problem class. Layer non-uniformity is a distortion of the internal interface that can be seen as a migration or displacement of the more viscous fluid by the less viscous one.

A three-dimensional finite element code was developed to study fundamental issues in the layer non-uniformity problem. One area of study is the contact line region (where the fluid/fluid interface meets the wall). Use of the classical no-slip condition leads to a mathematical singularity. In the past, this was circumvented by extrapolation methods. In this work, a localized slip model allowed a detailed study of the interface behavior near the wall. Also, a rigid (or "stick") contact line was used to explain certain experimentally observed interface shapes.

Based on experimental evidence, two distinct interface deformation mechanisms are proposed: Type I shows a displacement of the more viscous fluid by the less viscous one, with a slippage of the contact line. In Type II, there is an intrusion of the less viscous fluid into the more viscous fluid. Type I and II deformations can be captured using the 3-D thermal model formulation described in this work, but the shape depends on the interplay between the material and die parameters. The value of the slip coefficient at the contact line is important and may be a fundamental characteristic of the particular polymer melt I polymer melt I die material system.

A detailed study of the effect of thermal and geometrical parameters on the final interface shape was conducted. It was found that the thermal dependence of viscosity plays the most important role in determining the final interface shape as compared against other material parameters. The effect of this parameter is more pronounced near the die walls, where the viscous dissipation is higher. The code shows excellent agreement with experimental data for polycarbonate/polycarbonate extrusion systems.

An alternative analysis for the three-dimensional flow of viscoelastic flow in ducts was presented as an attempt to explain experimentally observed complicated interface shapes that cannot be captured by a Generalized Newtonian Fluid model. A modified Phan-Thien Tanner model and a second-order model are used in conjunction with a space-marching finite element code based on the Parabolized Navier-Stokes equations to study the secondary flows in channels.

abstract: Doctor of Philosophy (PhD)


title: Polyurethane Surfaces Bearing Immobilized Thrombin Binding Agents: Preparation and Interactions with Plasma

contributor:
Brash, J.L.
Chemical Engineering

abstract: Novel polyurethanes bearing O-phe-pro-arg chloromethylketone (PPACK), sulphonate groups and polyethylene oxide were synthesized using block copolymerization and chain-grafting methods. The structure and the PPACK attachment mode of the PPACK-bearing polyurethane were studied by 2D NMR. The distribution of the functional groups on the corresponding biomaterial surfaces was studied by XPS. PPACK was grafted onto the polyurethane chains in such a way that its bioactivity (interactions with thrombin) was retained. The protein layers deposited from plasma onto the different polymer surfaces were studied by SDS-PAGE in conjunction with immunoblotting methods. The initiation and generation of active coagulation factors in plasma contacting different polymer surfaces were investigated by chromogenic substrate methods using specific oligopeptide substrates. The polyurethane bearing PPACK residues effectively inhibited the activation and generation of factor Xlla and thrombin in plasma contacting the surface, and prevented the clotting of the plasma. This much improved in vitro biocompatibility indicated the validity of using non-heparin antithrombin agents to prevent surface induced coagulation, and it showed that the PPACK-based polymers have potential as novel biomaterials to improve the biocompatibility of current medical devices such as small diameter vascular prostheses, hemodialyzers, stents, and catheters.

abstract: Doctor of Philosophy (PhD)


title: Energy Margin Calculation by the Relevant Fault-on Trajectory Method

contributor:
Alden, R.T.H.
Findlay, Raymond D.
El-Kady, Mohamed A.
Electrical Engineering

subject:
Electrical and Electronics
Electrical and Electronics

abstract:
The value of the time domain simulation technique for power system transient stability analysis can be greatly enhanced if it can indicate the degree of stability by producing a stability index. Often referred to as Energy Margin, the stability index offers additional insight into the transient stability problem being studied, and has the capability of speeding up transient stability limit derivations. Moreover, energy margins also have potential applications in dynamic contingency ranking and screening.

This thesis presents a new method, called the Relevant Fault-on Trajectory (RFT) method, for incorporating energy margin calculations into time domain simulations. The proposed method is based on the determination of the additional energy absorbing capability of the critical generator group, at the instant when the transient kinetic energy injected into this group by the disturbance is fully absorbed. The additional energy absorbing capability is obtained through the simulation of a relevant fault-on trajectory. The RFT method computes energy margins efficiently and reliably for systems exhibiting either plant mode or area mode stability problems.

The practicality of the proposed method has been successfully demonstrated on a 27-generator, an 89-generator, and a 144-generator system. The RFT method has the capability of speeding up transient stability limit derivation by reducing the number of stability runs.

abstract: Doctor of Philosophy (PhD)


title: Ice Binding Structure and Mechanism of an Antifreeze Protein from Winter Flounder

contributor:
Yang, Daniel S.C.
Biochemistry

subject: Biochemistry Biochemistry

abstract: The 1.5Å x-ray crystal structure of a lone α-helical antifreeze protein (AFP) from winter flounder is presented, providing the first detailed look at an AFP and its ice binding features. The structure was determined using a non conventional multi-parameter molecular replacement scheme with two idealized α-helices as the search models. The described method may prove useful for the determination of other α-helical structures. The AFP's ice binding structure consists of four repeated ice binding motifs (IBMs), the side chains of which are inherently rigid or restrained by pair-wise side chain interactions to form a flat binding surface. Comparison shows that analogous IBM sequences are found highly conserved in all members of the α-helical class of AFPs. Also revealed are the presence of elaborate N- and C-terminal cap structures which help to account for the AFP's unusual stability for a lone a-helix in aqueous solution. Based on the crystal structure, a model amenable to testing is proposed which accounts for the proteins ice binding ability and specificity. Experiments to test the validity and generality of this ice binding model are proposed.

abstract: Doctor of Philosophy (PhD)


title: A Hopeless Struggle: The Astro-Hungarian Army and Total War, 1914-1918

contributor:
Campbell, J.P.
History

subject: History History

abstract:
This dissertation is an institutional study of the Austro-Hungarian Army during the First World War. It analyzes the operations of five infantry divisions, fighting on several different fronts, to reach conclusions about the wartime performance of the multinational Habsburg Army. The dissertation focusses on both tactical and socioetlmil; aspects of battlefield effectiveness. It is therefore a novel approach, combining operational and social history.

The first chapter is an overview of the Austro-Hungarian Anny in 1914, on the eve of the war. It deals with overall army organization, the nationalities issue, war plans and strategy, weaponry, and tactical doctrine to reach conclusions about the preparedness of the Habsburg Army for total war.

The second chapter deals with the battlefield performance of the Bohemian 21st Landwehr Infantry Division in 1914. This largely Czech formation fought in failed campaign against Serbia from August to December. It suffered the first Austro-Hungarian defeat of the war, participating in three major offensives in five months.

The third chapter focusses on the 1915 campaigns of the Magyar-Romanian 17th Infantry Division, recruited in South-Central Hungary. The division fought against the Russians on the Hungarian frontier in the Carpathians during the winter and spring. It defended the Carpathian passes and participated in the Gorlice-Tarnów breakthrough. In May 1915 the division moved to the opening Italian front, where it successfully resisted the first Italian offensives in Carinthia and on the Isonzo.

The fourth chapter details the 1916 fighting record of the West Galician 12th Infantry Division. This largely Polish formation, like so many Austro-Hungarian divisions, enjoyed a tranquil first half of 1916, but was defeated by the Russians during the June Brusilov offensive and the battles which continued all summer in East Galicia and Volhynia.

The fifth chapter analyzes the performance of the 55th Infantry Division during the 1917 Caporetto offensive. The 55th, a Bosnian-German mountain division, defeated several Italian formations in October and November, and played a decisive role in Austria-Hungary's victory in the offensive, the most successful Habsburg effort of the war.

The sixth and final chapter deals with the North Bohemian 29th Infantry Division on the Italian front during 1918. This German-Czech formation participated in the failed June offensive on the Piave, the last Austro-Hungarian offensive of the war. It resisted the Italian "victory offensive" in late October, and managed to escape Italian captivity, retreating home in good order.

This dissertation contradicts the prevailing historical perception that the wartime Austro-Hungarian Army was crippled by the nationalities issue. Instead, this revisionist work suggests that purely military shortcomings--principally poor high level leadership and a lack of industrial capacity--were the main causes of Habsburg defeat, and that the army actually perrormed respectably throughout the First World War despite its inherent weaknesses.

abstract: Doctor of Philosophy (PhD)


title: Apprenticeship's Legacy: The Social and Educational Goals of Technical Education in Ontario, 1860-1911

contributor:
Weaver, John C.
History

subject: History History

abstract:
The regime of apprenticeship, which provided both the foundation for a craft culture and basis of the social construction of skill in a pre-industrial society, was gradually supplanted by a regime of prescribed and systematic instruction. The development of technical education initiated a process which, over time, tied apprentices and workers more directly into the formal institutions of the community and the state to an extent that surely would have perplexed mid-nineteenth century observers. The process would eventually give employers and the state greater leverage in controlling the outcome of skills training at the same time as economic and technological transformations were giving employers greater leverage to control the mechanisms and procedures of production.

Formal technical education, like the public school itself, was a product of modernity. From the 1800s through the early 1900s, the normal sites of technical education and skills training underwent a fundamental shift. The setting moved from the workplace to the classroom. Responsibility shifted from skilled proprietors to the state. The authority to refine, to replicate and to define the value of skills shifted from private artisans to public policy makers. The cultural relationships embodied in skills replication shifted from personal paternalism to impersonal bureaucracy.

What had been, in the pioneer past, a predominately private domain was becoming increasingly a public responsibility at the behest of educators, business and labour leaders alike. Gradually, through the development of organized technical education, a less formalized 'apprenticeship model of education' was transformed into a formal 'educational model of apprenticeship.' This dissertation traces that development through the lens of an ongoing dialectic between competing conceptions of technical education: culture and utilitarianism.

abstract: Doctor of Philosophy (PhD)


title: Time Variability of Circinus X-1

contributor:
Sutherland, Peter G.
Physics

subject: Physics Physics

abstract: The current interest in the X-ray source Circinus X-1 stems from its similarity to Cygnus X-1, the prime black hole candidate. In this thesis Circinus X-1 will be examined in terms of time variability from data obtained by the first High Energy Astronomy Observatory (HEAO-1) during August 1977. The study involves the determination of time averaged characteristics in the form of statistical moments, hardness ratios, and correlation functions. Also included is a brief history of X-ray astronomy, the energetics of X-ray emission from compact stellar objects, followed by a description of the HEAO-1 satellite and a review of previous work on Circinus X-1 and Cygnus X-1.

abstract: Master of Science (MS)


title: Regulation of Pyruvate Dehydrogenase Activity In Human Skeletal Muscle

contributor: Medical Sciences, Division of Physiology/Pharmacology

subject:
Medical Pharmacology
Medical Physiology
Medical Pharmacology

abstract:
Regulation of the flux-generating enzyme complex pyruvate dehydrogenase (PDHc) was examined in the context of its physiological function in human skeletal muscle. In the first two studies, the role of PDHc in intramuscular fuel selection and the mechanisms regulating PDHc transformation from its inactive form (PDHb) to its active form (PDHa) and PDHa activity were examined. In a third study, the role of PDHc in muscle lactate production during exercise and recovery was assessed and the factors controlling transformation to PDHa were also examined.

In the first study, 5 subjects were examined during rest and cycling exercise at 75% of VO₂max after 3 days of consuming a low-carbohydrate (LCD) or high-carbohydrate (RCD) diet In the second study, 8 subjects were examined at rest and during cycling exercise at 40% and 80% VO₂max while they were infused with sodium acetate (ACE) or sodium bicarbonate (BIC). At rest, consumption of a LCD and ACE infusion increased the intramuscular acetylCoA-to-CoASH ratio and citrate, as a result of increased oxidation of available fat fuels and acetate, respectively. Elevation of the acetylCoA-to-CoASH ratio and citrate inhibited PDHa and phosphofructokinase activity, respectively. Consequently, the rates of pyruvate oxidation by PDHa and pyruvate production by glycolysis were reduced preventing the oxidation of intramuscular glucose. The resting results of these two studies were consistent with the operation of a reciprocal cycle of glucose and fat oxidation for intramuscular energy production. The events leading to glucose restriction were initiated by changes in acetylCoA accumulation which caused an increase in the acetylCoA-to-CoASH ratio and citrate concentration which induced the transformation of PDHa to PDHb and inhibition of glycolytic flux, respectively.

In contrast, during exercise at 40%, 75% and 80% VO₂max, transformation from PDHb to PDHa was determined by Ca²⁺ and was not restricted in any of the conditions except the LCD condition. Lower PDHa activity and incomplete transformation to PDHa occurred in this condition, placing a restriction on intramuscular glucose utilization. However, the acetylCoA-to-CoASH ratio actually decreased in this condition, suggesting that the lower rate of transformation was independent of alterations in the acetylCoA-to-CoASH ratio. In contrast, when transformation to PDHa was not limited in any other condition there was an increase in the acetylCoA-to-CoASH ratio which should have limited transformation. Thus, during exercise, the restriction on muscle glucose oxidation occurred only after a LCD indicating that this reciprocal cycle of fuel selection and utilization was also operating during exercise and that PDHc transformation was an integral part of its operation. However, during exercise, the regulatory factors controlling PDHa differed from those that determined the activity of this enzyme at rest. Lower PDHa during exercise in the LCD condition was consistent with an increase in the PDH-kinase/PDH-phosphatase activity ratio, in the 3 day period before exercise, increasing the occupancy of monophosphate esters on both the transformation site and the inhibitory sites of the Elα components. Incomplete removal of these additional phosphate esters by PDH-phosphatase during exercise may have then resulted in lower PDHa and glucose conservation later on during exercise.

In a third study, the role of PDHa in muscle lactate production during exercise and recovery was examined and the factors controlling PDHc transformation were determined in 7 subjects. During repeated 30 second bouts of maximal isokinetic cycling exercise, complete transformation to PDHa occurred concurrently with muscle lactate accumulation and increased mitochondrial oxidation, indicating that lactate production was not dependent on the development of tissue hypoxia. Instead, during exercise muscle lactate production resulted from a rate of glycolytic pyruvate production that was greater than PDHa activity. Conversely, during recovery, net lactate oxidation occurred as the lactate dehydrogenase equilibrium shifted more toward pyruvate production and PDHa remained partially active due to attenuation of the acetylCoA-to-CoASH ratio, reductions in the ratios of NADH-to-NAD and ATP-to-ADP and elevated concentrations of hydrogen ion and pyruvate.

The present studies extend the analysis of PDHc regulation from in vitro and in situ studies to human skeletal muscle in vivo. The findings of the present studies suggest that the during muscle contraction the most important factor regulating PDHc transformation in human muscle is probably Ca⁺, while the other regulatory factors perform secondary roles. In contrast, during rest and recovery from maximal exercise, PDHc transformation to PDHa and PDHa activity are determined by the intramuscular ratios of acetyICoA-to-CoASH, NADH-to-NAD, ATP-to-ADP and the concentrations of hydrogen ion and pyruvate.

abstract: Doctor of Philosophy (PhD)


title: Solution properties of cationic hydrophobically-modified hydroxyethyl cellulose ethers

contributor:
Winnik, Francoise M.
Chemistry

subject: Chemistry Chemistry

abstract: This doctoral thesis has investigated various aspects of the solution properties of water-soluble amphiphilic polymers. The ultimate goal was to achieve a better understanding of the macroscopic phenomena demonstrated by these systems by elucidating the molecular interactions causing them. Two commercial cationic cellulose ethers were studied, the cationic derivative of hydroxyethyl cellulose, HEC-N+CH3 and its hydrophobically-modified analogue, HEC-N+C12 . Their interpolymeric associations and their interactions with surfactants were studied using photophysical techniques, such as UV-vis and fluorescence spectroscopy. Initial fluorescence probe experiments were directed at investigating the interactions between these cationic polymers and a series of cationic surfactants. No interaction was predicted to occur in systems where the polymer and surfactant were of the same charge due to electrostatic repulsions. However, the results obtained clearly indicated that polymer/surfactant complexes formed if the polymer contained hydrophobic groups. A more detailed picture of the interactions was then obtained by using polymers to which the dye was covalently attached via an ether linkage. Various pyrene labelled and naphthalene labelled analogues of the two cellulose ethers were synthesised and characterised by standard methods. The interpolymeric associations of cationic polymer solutions was studied using mixed solutions of naphthalene and pyrene labelled polymers using non-radiative energy transfer experiments. Fluorescence studies of these labelled polymers in the presence of cationic surfactants confirmed the results of the probe studies. Other fluorescence studies investigated the interactions of the pyrene labelled HEC-N+C12 with a series of anionic surfactants. A stronger interaction was observed due to the electrostatic attraction of the two species. Additionally, an unexpected feature of the fluorescence spectra led to the speculation of the presence of two possible labelling sites on HEC-N+C12 . Fluorescence quenching experiments confirmed this hypothesis. To study the microenvironment around each site, specifically pyrene labelled cationic hydrophobically-modified hydroxyethyl cellulose ethers were prepared and characterised. An analogous series of naphthalene labelled polymers were prepared for investigations of the interpolymeric associations of polymers of like charge using mixed naphthalene and pyrene labelled polymer solutions. Other investigations of these polymers include studying how the site of hydrophobic modification affects the solution properties of the polymer and the interactions of mixed polymer/surfactant systems. The interactions that occur simultaneously at the air/water interface have been studied briefly for example in the investigations of the relationship between the interfacial composition and the interfacial viscoelastic behaviour and the foaming properties of polymer/surfactant systems. It was found that in a critical surfactant concentration region, interaction occurs between polymers and surfactants of opposite charge at the air/water interface. This surface flow behaviour was more prevalent in systems where the polymer was also hydrophobically-modified. Dynamic surface tension experiments were conducted to investigate the surface behaviour of dilute aqueous solutions of these cellulosic polyelectrolytes.

abstract: Doctor of Philosophy (PhD)


title: Using external information for statistical process control

contributor:
MacGregor, John F.
Chemical Engineering

abstract: This research presents practical solutions for several problems in the case of multivariate statistical process control (MSPC) for process monitoring and fault diagnosis of industrial processes. Various types of external information are used with multivariate statistical models to deal with fault detection and isolation (FDI) problems. The first part of the research deals with the fault isolation problem. It is based on the fact that MSPC approaches have been found to be very useful for fault detection, but less powerful for fault isolation because of the non-causal nature of the data. To improve fault isolation, an approach is proposed that uses additional data on past faults to supplement existing contribution plot methods. This approach extracts steady-state fault signatures of faults in both the correlation model space and the residual space. The use of transient fault trajectory or initial fault signature would minimize detection delay and false isolation of a fault. An indirect usage of process dynamic information to deal with FDI problems is proposed in the second part of the work. Since process signals represent the cumulative effects of many underlying process phenomena, multiresolution analysis via wavelet transformations is used to decompose signals. The third part of this thesis examines both the fundamental and the practical differences between the causal and statistical model-based approaches to FDI. The causal-model-based approach is based on causal state variable or parity relation models developed from theory or identified from plant test data. Faults are then detected and isolated with structured or directional residuals from these models. MSPC approaches are based on non-causal models built with multivariate latent variable methods using historical process data. Faults are then detected by referencing future data against these covariance models, and isolation is attempted through examining contributions to the breakdown of the covariance structure. Most processes are subject to change of the operating conditions such as feed rate and composition, product grade, controller status, and so on. Sometimes these large common-cause variations disguise or distort the relevant information to faults. This difficulty can be minimized if one builds a correlation model that includes only the process variations relevant to FDI. By incorporating various types of prior knowledge into the empirical model building process, one can estimate a hybrid correlation model that includes both raw data and prior knowledge. Application of the hybrid correlation model for process monitoring and fault diagnosis is proposed and used for analyzing a real industrial dataset. (Abstract shortened by UMI.)

abstract: Doctor of Philosophy (PhD)


title: State Dependent Server Scheduling Rules in Polling Systems

contributor:
Gupta, Diwakar
Love, Robert F.
Todd, Terry D.
Management Science/Information Systems

subject: Management Information Systems

subject: Management Sciences and Quantitative Methods

subject: Management Information Systems

abstract:
A polling system is a cyclic queueing model with multiple customer classes and a single server. Each customer class has its own queue (station). After the server switches to a station, it serves customers waiting at that station according to a specified service regime, e.g., exhaustive, gated or globally gated. It then moves to the next station, following a strict cyclic order. These models have several application areas including computer and communication networks and multi-item production systems. For example, a Local Area Network (LAN) can be modeled as a polling system by defining the central processing unit as the server and the data transmission requests from each terminal as customers. Similarly, a multi-item production system can be modeled as a polling system by considering the flexible machining cell as the server and each product type as a different customer class. In most systems that polling models are used to represent, the server requires time to switch and/or setup before it may start serving a different customer class. These processes (switching/setup) may take considerable amounts of time, and when that happens, it is undesirable to setup for a product type if there are no (or only a few) jobs of that type in the system. Therefore, a server scheduling policy that ignores system state information can easily lead to suboptimal performance.

Whereas most previous studies on polling models have assumed that the server behaves independently of the state of the system, we discuss two kinds of state-dependent server scheduling rules: i) the threshold setups model, and ii) the threshold start-up model. In the former model, the server does not setup (and does not serve any customers) at a station at which it finds less than a critical number of waiting customers, called the setup threshold. In the latter model, the server starts idling each time the system becomes empty, and it stays idle until arrivals to the system reach a critical number, called the start-up threshold. The server then resumes service from the station where it had stopped. Our analysis makes it possible to compare system performance under these state-dependent server scheduling rules and state-independent rules.

In this dissertation the following results are achieved. We develop an exact analysis for the one-threshold setup model with two stations, and an efficient approximation for the same model with any number of stations. For the general threshold setups model, we construct a numerical solution technique which is near-exact for calculating queue length distributions and station mean waiting times. The threshold start-up model is analyzed in detail, and mathematically exact expressions for man station waiting times are obtained for both exhaustive and globally gated service regimes. For each model, the extension to the gated service regime is also discussed.

abstract: Doctor of Philosophy (PhD)


title: Uniform Modules Over Goldie Prime Serial Rings

contributor:
Müller, B.J.
Mathematics

subject: Mathematics Mathematics

abstract:
We investigate the uniseriality of uniform modules. Let R be any ring and fix a decomposition 1 = ℯ₁ + ℯ₂ +…+ℯn into orthogonal idempotents. Let Vʀ be uniform and injective; we prove that there exists ℯ = ℯᵢ such that VR ≅ homA (Rℯ, Vℯ) where A = ℯRℯ. Moreover, Vℯ is a uniform injective A-module. If R is Goldie prime serial, we prove that V is uniserial if and only if Vℯ is uniserial as an A-module.

If R is Goldie prime serial, we know that such an A is a valuation on a division ring D. We prove that any uniform injective, EA , is of the form E = E (D/I) for some I ≤ A. If D/I is injective, then E is uniserial. We give several necessary and sufficient conditions for D/I to be injective.

In this study of uniform injectives over Goldie prime serial rings we define a notion of generalized associated primes. This leads to a semiprime Goldie ideal, S, which can be associated to any uniform injective. We prove that for certain uniform electives, C(S) (the set of elements regular modulo S) is the largest Ore set operating regularly on the module.

abstract: Doctor of Philosophy (PhD)


title: Escherichia coli long-chain fatty acid uptake: Molecular and biochemical investigation of proteins involved in fatty acid uptake across the cell envelope

contributor:
Gerber, Gerhard E.
Biochemistry

subject: Biochemistry Biochemistry

abstract: E. coli can utilize long-chain fatty acids (LCFAs) as its sole carbon and energy source. This requires the coordinated expression of several proteins involved in the uptake and metabolism of LCFAs. The genes encoding these proteins are unlinked but regulated by the global repressor protein FadF, which makes up the fad regulon. We developed a novel method for monitoring LCFA permeation across the OM. Expression of FadL significantly increased labeling of the fusion protein. Treatment of E. coli with the outer membrane-permeabilizing reagent EDTA, also increased the labeling of the fusion protein to an even greater level. The role of Tsp in LCFA uptake has not been well defined. To determine if the periplasmic protease played a direct role in uptake, we investigated various ways in which Tsp might participate. Photoaffinity labeling with the photoreactive fatty acid suggested that Tsp has low affinity for fatty acids and is therefore unlikely to represent a periplasmic fatty acid binding protein. Preliminary evidence had suggested a link between Tsp protease and FadD cleavage, but our data demonstrated that Tsp is not required for FadD proteolysis. We then investigated the possibility that Tsp was mediating its effects on LCFA uptake through FadL. There were no apparent differences in the expression levels or LCFA affinity of endogenous FadL between tsp mutants and wild type E. coli . However, FadL overexpression experiments revealed that tsp mutants overexpressed the OM protein at reduced levels relative to wild type. Purification of FadD, the E. coli fatty acyl-CoA synthetase, is a difficult endeavor since low yields of unstable enzyme samples are typically obtained. Discrepancies in the description of native FadD complicate matters further. To overcome some of these technical difficulties, we developed overexpression systems for FadD and a FadD fusion protein. The FadD fusion protein was purified to high levels and free of degraded enzyme, which was a problem encountered when purifying FadD. We report that FadD enzyme is cleaved by the outer membrane protease OmpT, producing a 43-kDa carboxyl-terminal and a 19-kDa amino-terminal fragment, which remain tightly associated. OmpT-mediated proteolysis of FadD showed that the fatty acyl-CoA synthetase undergoes conformational changes in the presence of specific substrates including oleate, which inhibited cleavage. (Abstract shortened by UMI.)

abstract: Doctor of Philosophy (PhD)


title: Co-deformation of a two-phase FCC/BCC material

contributor:
Embury, J.D.
Weatherly, G.C.
Materials Science and Engineering

subject:
Materials Science and Engineering
Materials Science and Engineering

abstract: The drive to produce materials with novel or beneficial combinations of properties has prompted research into a range of new materials and processing routes. In many applications one of the important design variables is the mechanical strength. Exceptional strengths can be achieved in certain materials consisting of two deformable phases when they are drawn into fine wires or rolled into thin sheets, the common example being pearlitic steel wire which can achieve strengths in excess of 5 GPa. The mechanisms that permit co-deformation and result in the observed strengthening are, however, not well understood. In this thesis an approach was adopted whereby co-deformation of a well characterized model material has been studied primarily using uniaxial tensile tests. Directional solidification of a Cu-1.56at%Cr eutectic alloy has been used to produce material consisting of submicron diameter single crystals of Cr embedded within a polycrystalline Cu matrix. It has been shown that these two phases exhibit preferred crystallographic orientation relationships, habit planes and growth directions the same as those found for solid state precipitates of Cr in Cu. On deforming this material it is found that the Cr fibres yield at stresses close to the theoretical limit. However, their are able to continue to co-deform with the Cu matrix to large plastic strains. This process of co-deformation is observed to cause a rate of nearly constant work hardening that results in both high strength and high ductility. This behaviour has been attributed to the fact that the Cr fibres continue to carry increasing elastic strain beyond their yield thereby contributing to an increasing level of internal stress in the material. It is suggested that this mechanism may play an important role in other co-deformed two phase materials. In particular, it is suggested that this may provide one mechanism for the continued high rate of work hardening in heavily co-deformed two phase materials.

abstract: Doctor of Philosophy (PhD)


title: Statistical Analysis and Adjustment of the Mass/Energy Balances of Processes

contributor:
Crowe, C.M.
Chemical Engineering

abstract:
An improved technique for data adjustment to satisfy mass/energy balances for single or multiple processing unit systems has been developed. The method was successfully tested on examples from the literature. With this technique, biased data can be detected and sources of error identified and isolated.

A multivariate normal distribution for the measurement vector x, was assumed and used to derive a test function vector w, with univariate normal distribution. A chi-square test on w is proposed for detecting biased data. An algorithm for identifying and isolating sources of bias was developed, using standard normal two-sided tests on each element of vector w and using the imbalance of the constraints, e.

In the absence of bias, adjusted values of the measurement vector and/or the estimates of missing variables can be obtained. When chemical reactions take place, the extents of the independent reactions are also estimated.

The main requirements of this technique are the knowledge of the process constraints and measurement statistics.

Implementation of the technique is straightforward and it is suggested that the method be used as a diagnostic aid in process analysis.

abstract: Master of Engineering (ME)


title: Evaluation of Immune Responses and Protection in Mucosal Tissues Following Intranasal Immunization With a Recombinant Adenovirus Vector Expressing Glycoprotein B of Herpes Simplex Virus

contributor:
Rosenthal, Kenneth L.
Biology

subject: Biology Biology

abstract:
In recent years there has been an increased interest in the design of vaccines capable of inducing immune responses in mucosal tissues and of providing protection against pathogens that invade through mucosal surfaces. Much of this interest has developed as a direct result of our greater understanding of the unique immune functions present in mucosal tissues. Numerous vaccine strategies have been developed to induce immunity in mucosaltissues and provide protection. The studies outlined in this thesis have utilized a recombinant adenovirus vector encoding the 0herpes simplex virus glycoprotein B (gB) gene (AdgB8) as a mucosal vaccine vehicle. The induction of gB-specific mucosal humoral and cellular immune responses was evaluated following intranasal and systemic routes of immunization. Immunological memory was also examined as was protection against mucosal infections with herpes simplex virus type-2 (HSV-2).

Previous work has shown that adenovirus vectors expressing glycoprotein B of HSV-I are capable of inducing systemic antibodies and protection against systemic HSV infection. Evaluation of mucosal immune responses following intranasal AdgB8 immunization demonstrated IgG and IgA antibodies in mucosal secretions of the respiratory and genital tract. In contrast, systemic immunization only resulted in IgG antibodies in the genital tract. A thorough examination of antibody levels in the female genital tract revealed an isotype dependency on the stages ofthe estrous cycle. These observations become important when considering the maintenance of immunity throughout the estrous cycle.

Currently, our understanding of the homing and recirculation patterns of memory lymphocytes suggests that immunological memory may depend on the tissues in which immune induction occurred. In addition, lymphocytes originating in mucosal tissues selectively migrate to local and distal mucosal tissues. To examine these phenomena functionally, CTL memory responses were evaluated in mice immunized with AdgB8. Functionally, short- and long-term CTL memory was found to depend on the route of immununization. These results are consistent with the recent literature and expand our current understanding of immunological memory on a functional level.

Protection studies were then performed to examine the role of intranasal and systemic immunization in resistance to HSV-2 infections of the respiratory and genital tracts. From these studies it was clear that intranasal immunization provided optimal long-term protection. Taken together, the results presented here will have important implications in terms of developing successful mucosal vaccines designed to provide protection against sexually transmitted pathogens.

abstract: Doctor of Philosophy (PhD)