VictorJuiz/thesis huggingface dataset:
The role of polysialic acid in neuronal development

The aim of this thesis was to investigate the significance of polysialic acid (polySia or PSA1) in modulating the plasticity of immature neurons in the developing and adult brain. PSA is an unusually long chain of sialic acid residues expressed on the neural cell adhesion molecule (NCAM). The expression of PSA is restricted to the embryonic brain and areas of neurogenesis in adulthood. Thus it has been proposed that PSA functions to promote neuronal plasticity. It has been suggested that the very large and negatively charged PSA is able to sterically hinder receptor interactions on cell membranes and between adjacent cells. By creating a voluminous space on the cell membrane, PSA limits stable attachments formed by NCAM-mediated adhesion and thereby promotes migration and neurite outgrowth. In the first part of this thesis we examined the role of PSA in the development of septal neurons, which are known to be important in learning and memory and affected in neurodegenerative disease. Our results showed that PSA limits septal neurite outgrowth in culture by preventing neuron-substrate contacts. We also demonstrated that PSA restricts a cholinergic phenotype in septal neurons, as measured by choline acetyltransferase (ChAT) activity. PSA limited ChAT activity by minimizing the responsiveness of the neurons to brain-derived neurotrophic factor (BDNF). ChAT activity was also found to be improved by homophilic stimulation of NCAM, the carrier of PSA. In the second part of this thesis, we examined the role of retained expression of PSA on neural progenitor cells of the dentate gyrus of the hippocampus. Our results revealed that PSA is important for mediating the clustering and migration behaviour of the adult neural progenitor cells to ensure their proper development. Together these data indicate that a significant role for PSA is to limit the interaction between growing neurons and their environment to orchestrate appropriate spatiotemporal neuronal development. Overall, this thesis provides new insight into the role of PSA as an important modulator of neuronal development, especially with regards to ChAT and progenitor cells. Keywords: Polysialic acid, neural cell adhesion molecule, neurite outgrowth, beta1 integrin, choline acetyltransferase, brain derived neurotrophic factor, mitogen activated protein kinase, C3d, neurogenesis. 1PSA is the abbreviation used for polysialic acid in throughout this thesis.
A search for the mechanisms by which various iron levels modulate elastin production

Northern blot and real time RT-PCR analysis revealed that treatment with 20 muM iron led to sim;3-fold increase in elastin mRNA levels, while treatment with 200 muM iron decreased elastin message stability and subsequent mRNA levels. It has been implicated that iron imbalance is responsible for the elastic fiber defects in hereditary hemolytic disorders, and since the expression of several ECM is iron dependent, we speculated that iron might also modulate elastin gene expression. We conclude that a balance between these two iron-dependent mechanisms may constitute a novel factor regulating normal elastogenesis and that disturbance of this balance results in impaired elastic fiber production. The results of our immunocytochemical and metabolic studies assessing deposition of insoluble elastin, showed that treatment of cultured fibroblasts with 2--20 muM of iron (supplied as ferric ammonium citrate) induced an increase in elastin production, while treatment with 100--200-muM iron lead to intracellular reactive oxygen species generation, and a decrease in elastin production.
Facing intolerance: Toronto black university students speak on race, racism and in(e)(i)quity

This thesis examines the experiences of 12 young Black women and men in a hostile tertiary educational environment in Toronto. I critically analyze the impact of racism and racial discrimination on the everyday lives of the Black students, and the fact of schools and university campuses as seemingly uncontested sites for the reproduction of racist power relations and even outright hatred. This is an ethnographic study that utilizes an anti-racist, Black feminist perspective---the perspective of the "strong-willed resister" (Collins, 2000, p.98)---able to locate the racialised participants of this study at the centre of the research as "producers of knowledge and not merely consumer". What is palpable from the students' narratives, presented in their own words, is the need for ongoing critique and confrontation of racial oppression in Canadian society. The findings of this study provide clear evidence of the fact that despite the oppressive nature of Black life, the structured oppression that Black people face from early childhood in Canadian society, many still manage to succeed in the education system and become productive citizens contributing to overall societal development. Black women and men have managed and continue to manage to do intellectual work at all levels of society and many do this with a fierce commitment to "racial uplift". In fact, the desire to be engaged in self-reflection, self-improvement and community development work evidenced in the statements made by several of the young people interviewed for this study is commendable in view of the various economic and social oppressive forces they face in their own lives. The young people are empowered to form coalitions with others in and outside their particular communities. They confirm the need for support from academic institutions, governments, community agencies and families to make it possible that they learn their histories so as to gain the knowledge and language to contest the racist attacks that are fully part of the culture of their everyday and which irrefutably permeates every aspect of Canadian society.

Keywords: Racism, Ontario
Racism in education, Ontario
College students, Black, Attitudes
College students, Black, Ontario
Identity (Psychology)
Vertical transfer of training: Can one person make a difference?

The transfer of training literature has focused primarily on the individual as the unit of analysis. The question of whether training an individual influences a group's performance has yet to be investigated empirically. In the present study, participants (n = 275) were randomly assigned to groups (k = 55) of five. Individuals were then randomly selected from those groups such that none, one, three, or all five members of the group participated in training on effective ways to select a job candidate. The extent to which the knowledge acquired by one or more individuals was used by the group in making a selection decision was evaluated. Vertical transfer occurred according to a negatively accelerating curve. As the number of people trained increased beyond three, the amount of influence exerted by the fifth individual decreased. Extroversion moderated the relationship between training an individual and vertical transfer. If the one individual who was trained was an extrovert, vertical transfer increased. Collective efficacy mediated the relationship between training one or more individuals and a group's performance.

Keywords: Personnel management
Organizational behavior
Dissertations, Academic, Canada
Adaptive spectrally efficient strategies for interference suppression in DS-CDMA systems

Novel adaptive strategies for maintaining quality of service (QoS) in mobile communications while maximizing efficiency are presented in this thesis. The unifying theme is that communication systems should adapt to the environment: when the channel is hostile, robust modes should be used to maintain good QoS; however, when benign channel conditions are encountered, higher-throughput modes should be invoked for efficiency. First, a time-varying channel model explicitly taking into account changing environments is developed. Under this channel model, methods for tracking channel stationarity are proposed based on analysis of variance, correlation and information-theoretic criteria. Tracking enables constructing variable-size bursts for efficiency. Next, adaptive modulation for improving throughput is proposed for uncoded and coded systems, respectively using mean-square error and bit-flipping metrics. Finally, performance of the proposed methods is evaluated in a semi-blind framework. Obtained results show feasibility of adaptive methods for improving efficiency compared to the non-adaptive counterparts.
Morphology of epitaxially self-assembled quantum dots

Three-dimensional theory of quantum dot growth is constructed from energetics of coherent nanometer-size islands in one-component strained layer epitaxy using nonlinear elasticity. The theory is amenable to statistical mechanical treatment and thus shows a great promise for predicting island size distribution. This attribute is crucial for ensuring timely technological applications of quantum dots, which rely on a uniform size distribution. Construction of the theory is motivated by our 2D model that incorporates surface and elastic strain energies. The 2D model predicts nucleationless islands of cellular morphology for strained layers grown near critical misfit strain. Qualitative predictions from the 2D model agree with measured size distributions and island slope histograms of SiGe islands. The 2D model cannot predict the thickness of wetting layer that forms in Stranski-Krastanow growth mode. A new methodology for representing time variable is proposed to analyze the evolution of island size distributions in multilayer deposition. The measured size distributions of SiGe islands exhibit a slow-decay at small sizes and an asymmetric bell-shaped distribution peaked at a large size. A size distribution model based on random percolation and Smoluchowski (coalescence) ripening gives a good agreement with the measured distributions. SiGe islands of low Ge fractions grow critically, while those with large Ge fractions develop size bimodality. Defect-mediated, first-order transitions occur for the latter and are confirmed by their slope histograms. The 3D theory simultaneously solves for the wetting layer thickness and equilibrium shapes of quantum dots. Thickness-dependent equilibrium morphologies are caused by a nonlocal surface force equilibrium. Order parameter for coherent islanding transition is shear strains along the growth direction. Coupling between adatoms and the order parameter is crucial for producing bulk shear deformation. First-order transition is predicted and adatom diffusion barrier determines the magnitude of discontinuity of the transition. The concept of transition thickness—the flat layer coverage needed by tetragonal strain to balance surface force from surface and interface tension—is introduced to explain the misfit sign dependence of strained layer stability. Under typical conditions, coherent layers in compression are unstable above the transition thickness, but become stable in tension.
The allocation of inorganic nitrogen (15NH4+) to soil, microbial and plant biomass in an Arctic salt marsh

This study has demonstrated, through the shared distribution of a single resource (15NH4+), that plants and soil microbes compete for inorganic N in a N-limited system. At La Perouse Bay, soil microorganisms out-compete plants for this resource, but their competitive advantage is dampened relative to microorganisms in other Arctic ecosystems by the effects of goose grazing that promote plant growth via the addition of faeces. There is a seasonal displacement of N allocation, as microbes continue to mineralize and slowly immobilize nitrogen in the winter. Loss of vegetation, as a result of goose grubbing, has led to changes in soil characteristics, including high salinity and low redox potentials. These edaphic conditions may dampen N-uptake by soil microorganisms in these disturbed soils. Seasonal and grazing effects interact to contribute to a large potential N loss from these soils, although this is minimized by the apparent abiotic fixation of inorganic N.
Optical signal processing using nonlinear periodic structures

This work advances the field of optical signal processing using nonlinear periodic structures. A novel approach to all-optical signal processing using nonlinear periodic structures is proposed. The nonlinear response of various materials is measured, and nonlinear periodic structures are fabricated and characterized. This work presents an analytical and numerical study of a stable all-optical limiter that clamps the output level below a design-specific limiting intensity. The introduction of disorder is predicted through theory to result in widening of the nonlinear stopband, localization of light, and formation of stationary gap solitons. It is shown through development and solution of a model that the incorporation of a built-in linear out-of-phase grating into the index-matched limiting structures can enable signal processing functions of hard-limiting, analog-to-digital conversion, and logic gating. A comprehensive theory of intensity-domain optical stability in nonlinear periodic structures is derived and conditions for multistability are presented. The propagation of pulses in the structures proposed is analyzed and effects of pulse intensity limiting and pulse compression are predicted. The resonant, ultrafast, and thermal nonlinear properties of inorganic crystalline semiconductor, organic, and nanocrystal materials are examined while seeking to maximize the strength of the refractive nonlinear response and associated figures of merit. Nonlinear index changes of record magnitude of -0.14 with figures of merit of 1.38 are found for InAlGaAs/InGaAs semiconductor multi-quantum-wells under the illumination at a wavelength of 1.5 mum and a fluence of 116 muJ/cm2. Resonant nonlinear response is demonstrated in strongly-confined semiconductor PbS nanocrystals in the spectral region of 1150 to 1600 nm. The theoretical and experimental accomplishments of this work expand the field of stable and multistable optical signal processing functionality of nonlinear periodic structures; and map out future directions for enhancing the functional diversity and performance of elements required for optical networks. Nonlinear periodic signal processing elements are designed, fabricated, and analyzed. One dimensional semiconductor elements are shown to yield fluence-dependent transfer characteristics due to the interplay of the nonlinear Bragg refraction and nonlinear absorption. A photonic stopband is experimentally demonstrated to emerge in the vicinity of the wavelength of 1.5 mum at fluences below 320 muJ/cm2. Three-dimensional organic colloidal crystals are proven to exhibit a nonlinear shift in the position of the photonic stopband and a decrease in the reflectivity in the 530 to 570 nm spectral region.
Sensorimotor integration: Prehensile movements in conditions of visuo-proprioceptive conflict

Aim. To understand the integration of visual and proprioceptive information presented during planning of prehensile movements. Vision was expected to receive the highest sensory-weight; however, proprioception was expected to contribute to prevent prehension errors. Methods. In study 1, target size was the same as either the visual or proprioceptive cue (incongruent) or both (congruent). In study 2, congruency likelihood was manipulated (20%- or 80%-congruent trials). Conclusions. Although vision was weighted highest in most instances, large proprioceptive cues reduced this 'visual dominance' in conditions of sensory conflict. Large-size sensory cues caused the greatest change in kinematic grasp characteristics. Both modalities contribute to the planning of prehension using a principle based on avoiding prehension error. Results. In study 1, large incongruent proprioceptive cues affected behaviour (i.e., caused increased maximum grasp aperture). High congruency likelihood (80%-congruent) decreased aperture velocity and increased MGA. Effects on fingertip forces were not consistent in either study.
Morphology, flow hydraulics and sediment movement in rill networks

Interrill surface roughness on planar slopes begins as a normally-distributed function of particle size and aggregate size distribution and develops according to the presence of water stable aggregates and large clasts to determine initial stages of flow concentration and network development. Multiple aspects of rill network evolution are identified: scour hole and knickpoint formation on an initial surface; flow concentration; scour and knickpoint migration; knickpoint bifurcation and tributary development. Water and sediment budget dynamics are adequately explained by consideration of temporal and spatial variations in discharge, stream power, shear velocity and sediment transport capacity. Detailed measurements of flow characteristics at junctions show decreased velocities, shear stress and stream power, along with increased turbulence and frictional energy loss as a knickpoint migrates through the confluence hydrodynamic zone. Rill networks act as conduits that transfer water and sediment rapidly across the surface of hillslope systems. Knickpoint migration and birfurcation are key factors in network expansion, but their effects on network sediment delivery have received little attention, thus inhibiting their inclusion in general concepts of hillslope sediment delivery. Understanding water and sediment movement through rill networks allows forecasts of sediment transport and erosion processes to be made, and is central to the study of landscape evolution and implementation of soil erosion control measures. Three sets of laboratory flume experiments are undertaken to examine the evolution of a rill network and the area it drains, how this is organized during a storm period and resulting morphological response. The purpose of this study is to: (1) examine the evolution of soil surface roughness on different slope angles during the initial stages of a storm; (2) describe the mechanisms of rill network inception and expansion; (3) prepare sediment budgets for rill networks developed on a natural soil under simulated rainfall in a laboratory flume; (4) identify changes is the relationship between hydraulic indices and sediment transport as a network expands; and (5) identify the effect of knickpoint migration through confluences on rill hydraulics and sediment flux patterns.
Reading, writing and unheard voices: a history of literacy education in Canada, 1880-1950

This thesis explores the history of Canadian literacy education from 1880 to 1950. A central problem is why there was a need for adult literacy education in the decades after free, public elementary education expanded throughout much of Canada. Geography, finances, teacher quality, immigration and ethnicity, and other factors influenced why attendance and literacy rates were often low. Autobiographies, journals and other first-person writings from this period illustrate popular attitudes toward reading, writing, schooling and print culture. A critical analysis of Frontier College specifically reveals some of the tensions between the literacy organization's progressive and conservative elements. It also suggests some of the ways in which literacy education was used to control and silence workers. Nonetheless, the proliferation of first-person writings by diverse Canadians indicates that growing access to school and literacy offered more people a voice with which to record their own histories.

Keywords: Literacy, Study and teaching
Literacy, Canada
Literacy, History
Literacy, Canada
Educational equalization, History
Educational equalization, Canada
A fatherly eye: two Indian agents on Georgian Bay, 1918-1939

This thesis examines the implementation of federal Indian policy on the local level and the control exercised by officials of the Indian Department over Native individuals and communities. It does so by analyzing the activities and approaches of two Indian agents in the Georgian Bay area between 1918 and 1939: Robert J. Lewis of the Manitowaning agency on Manitoulin Island, and John M. Daly of the Parry Sound agency on the eastern shore of Georgian Bay. By comparing and contrasting the activities of these two men, the dissertation reveals the ways in which policies were applied and enforced. The overriding theme is the contest for power which dominated the interaction between Native people and field officials. Drawing on Michel Foucault's insights into power relations, the dissertation explores the strategic manoeuvring in which agents and their aboriginal clients engaged in order to exercise power. Many Native people challenged the authority of the agents, asserting their own vision of individual and community autonomy. They also addressed issues of treaty rights, aboriginal fishing and hunting rights, and control over band funds and resources. Field officials were often able to block aboriginal attempts to assert greater autonomy and to organize politically against the Department of Indian Affairs. On the other hand, the agents were limited in their capacity to act when they lacked the backing of headquarters. The dissertation also examines the role of Indian agents in providing assistance to their clients and mediating between reserve communities and the outside world. Agents sometimes acted as advocates of Native interests, both in interpersonal disputes and through efforts to ensure limited Native access to fish and game. In addition, Indian agents dispensed social services, largely in the form of financial assistance. The advocacy and assistance which the agents could provide were the object of power negotiations with Native people, in which the latter sought to derive benefit from the power of the field officials. At the same time, the authority of field officials was enhanced by their power to supply aid and intervene on their clients' behalf.

Keywords: Indians of North America, History
Indians of North America, Canada
Indians of North America, Government relations
Indians of North America, Canada
Land, food, freedom: struggles for the gendered commons in Kenya, 1870 to 2007

This study contributes to demonstrating how capital has organized, united and disciplined the exploited, both waged and unwaged, to resist their exploitation; and how, in the instances presented, peasant women have been at the forefront of these persistent, and increasingly global movements against capitalist enclosure. Kenyan commoners' world historic struggles provide critical examples for activists, scholars, commoners and others, of the reconstruction and defense of a life-centred subsistence political economy. The dynamics of popular struggles for the gendered commons in Kenya between 1870 and 2007 are traced through an analysis of fifteen instances of struggle, including short lived uprisings and long-term social movements. Special attention is paid to the gendered and ethnicized class character of Kenyan social movements and to the subsistence content of the relationships being wrought in the process of 'globalization from below.' This approach reveals: (1) the ways in which Kenyan peasant women have contributed to the mobilization of social movements for subsistence over the long twentieth century; (2) the ways 'gendered class alliances' and the creative amalgams of indigenous and exogenous 'social forms,' developed and used in the course of struggle, have been able to break the 'male deals' that channeled the fruits of Kenyans' fertility into the commodified marketplace, and (3) the potential of the subsistence-oriented demands of 21st century Kenyan social movements for strengthening Kenyan and global movements for the gendered