VictorJuiz/thesis huggingface dataset:
Signal and noise in perceptual learning

Performance in perceptual tasks often improves with practice. This effect is known as 'perceptual learning', and it has been the source of great interest and debate over the course of the last century. Although much is known about how perceptual learning changes the properties of cortical circuitry, little is known about how these changes manifest themselves at the level of behavior. In this thesis, the behavioral effects of perceptual learning are considered within the context of signal detection theory. Within a signal detection framework, an observer's sensitivity in a perceptual task is defined by the ratio of signal-to-noise within the system. Thus, according to signal detection theory, the improvements that take place with perceptual learning can be due to increases in 'internal signal strength' or decreases in 'internal noise'. These quantities cannot be measured directly. Instead, psychophysical techniques must be used to infer their magnitudes. In this thesis, two psychophysical techniques were used to discriminate between the effects of signal and noise as observers learned to identify sets of unfamiliar visual patterns. 'Noise masking' was used to measure observers' 'equivalent input noise' and ' calculation efficiency', quantities that correspond to internal noise and internal signal strength, respectively, within the context of a simple black-box model of the visual system. Equivalent input noise only reflects the effects of an internal noise whose magnitude is independent of the magnitude of the stimulus. 'Response consistency' was used to estimate the effect of learning on internal noise that depends on the magnitude of the stimulus. Calculation efficiency improved by as much as a factor of four across learning sessions for two very different pattern identification tasks (face and texture identification). However, neither form of internal noise changed significantly with learning. These results were used to test the prediction that an observer's calculation should become more similar to the calculation of an ideal discriminator with practice. 'Response classification' was used to estimate observers' linear templates as learning took place, and showed observer's calculations became significantly more correlated with the ideal template with practice. Taken together, these results place new theoretical constraints on models of perceptual learning.
A laboratory study of deposit removal by debonding and its application to fireside deposits in kraft recovery boilers

The accumulation of fireside deposits on heat exchange surfaces in a kraft recovery boiler drastically reduces the boiler thermal performance, restricts the flue gas flow, and in severe cases plugs the flue gas passages leading to unscheduled boiler shutdowns for cleaning. High-pressure steam sootblower jets are used to remove these deposits. Deposits may be brittle or "plastic", depending on their temperature, and may be removed by sootblowers by two main mechanisms: brittle fracture and debonding. Brittle fracture has been previously studied and applies only to brittle and low-strength deposits. Debonding is likely to be the main mechanism by which strong deposits are removed by breaking the weak bond between the deposit and the tube surface. Deposit removal by a debonding mechanism is the main subject studied in this thesis. To study the effects of aerodynamic drag and lift forces and flow induced vibrations on deposit debonding, the instantaneous drag and lift forces generated by a supersonic jet impinging on artificial deposits were measured in laboratory experiments. By numerical analysis, the fluctuation components of the drag and lift forces were decoupled from the flow-induced vibrations. Results showed that the lift force fluctuations and flow-induced vibrations acting on deposits increased and reached maxima at a distance of about 45-50 nozzle diameters downstream. The flow-induced vibrations were found to be much larger in the lateral direction than in the flow direction. These vibrations increase the lift force fluctuations by a maximum factor of '0.872 '/'ß0.5', where 'ß ' is the damping coefficient of the tube-deposit assembly. This is in good agreement with the results of the experiments, where the fluctuating lift forces were observed to be as effective as the mean drag force in removing artificial deposits. An analysis of the dimensionless power spectra of lift forces exerted on cylindrical deposits showed a high degree of similarity under a broad range of operating conditions. The information can be used to estimate the power spectra of lift forces exerted on deposits in full-scale boilers. The results would provide a basis for estimating the role of vibration in deposit removal in full-scale boilers.
Ground testing and model updating for flexible space structures

Aspects of the ground testing portion of the Dynamics Identification and Control Experiment (DICE) are explored. DICE is a proposed International Space Station (ISS) experiment whose goal is to investigate System Identification (SI) and attitude and shape control using a small free flying spacecraft, inside an ISS experimental module, that features a rigid central bus controlled using reaction wheels and an array of flexible appendages or 'ribs' fitted with control moment gyroscope end-effectors. Extensive testing prior to launch is required before a high quality 0-g math model can be predicted and the benefits of on-orbit system identification evaluated. To this end, two technologies are developed in this thesis. The first is a passive mechanical suspension system that allows dynamical ground testing in the fully deployed configuration, providing support for the DICE bodies, a zero deflection at-rest state, and high compliance for all degrees of freedom. Based on concepts from the literature combined with innovative design improvements, a prototype is built and evaluated, showing excellent performance in local mode suppression and damping. It is then successfully used in tests with one of the prototype DICE ribs. The second technology is a Model Updating (MU) technique that uses experimental data to fine tune the 1-g math model while retaining the ability to generalize the model to the 0-g case. The technique optimizes the parameters in the nonlinear model by making direct use of time history data from multiple ground test configurations and the weighted uncertainties of the parameters, thereby maximizing the validity of the extrapolated on-orbit model. Although more computationally intensive than other SI methods, the MU technique allows nonlinear models to be updated, retains physically meaningful model parameters and state-space (a requirement for the 0-g model prediction), and when demonstrated with real experimental data performs just as well in reducing model error as direct SI methods.
Evaluation of porcine acellularized dermal matrix as a biomaterial, in vitro fibroplasia

Acellularized pig dermis (pig ACM) is a biomaterial under study for use as a xenograft dermal substitute, and for modeling dermal matrix biology 'in vitro'. The specific objectives of the present project were threefold. (1) To characterize the structure and acellularity of pig ACM, in comparison with pig dermis and human ACM. (2) To study the effects of pig ACM on fibroplasia 'in vitro' in comparison with other 'in vitro' models of fibroplasia. (3) To evaluate the effects of hyaluronan and heparin on fibroplasia 'in vitro', after incorporation into pig ACM. Pig ACM was found to be inferior to human ACM as a scaffold for human fibroblasts. Fibroblasts proliferated more rapidly on pig ACM and differentiated into myofibroblasts to a greater degree. Hyaluronan-enriched pig ACM was associated with decreased myofibroblast differentiation, whereas a greater percentage of fibroblasts differentiated to myofibroblasts on heparin-enriched ACM. Hyaluronan, unlike heparin, may therefore be considered a useful ACM dermal substitute component. Pig ACM was found to be a promising material for 'in vitro' modeling of myofibroblast-mediated contraction of dermis. Structural modification of pig ACM would likely improve its clinical suitability as a xenograft dermal substitute.
The involvement of substance P in relapse to cocaine-seeking behaviour in rats

The aim of this thesis was to investigate the role of the neuropeptide substance P (SP) in mediating relapse to drug-seeking behaviour in rats. Experiment 1 showed that the SP analogue, DiMe-C7 (0, 1, 3, or 6[mu]g/[mu]l; 0.51/side) microinjected into the ventral tegmental area (VTA) significantly increased locomotor activity at all drug doses tested. Experiment 2 showed that intra-VTA injections of DiMe-C7 (0, 0.2, 1 or 5[mu]g/[mu]l) induced reinstatement of drug-seeking behaviour in a dose-dependent manner in animals previously trained to self-administer cocaine. Finally, experiment 3 showed that pre-treatment with the selective NK-1 receptor antagonist, Spantide II (0 or 1 [mu]g/0.5[mu]l), by injection into the VTA, did not block DiMe-C7 (0 or 1 [mu]g/0.5[mu]l)-induced reinstatement of cocaine-seeking behaviour, suggesting that DiMe-C7-induced reinstatement may not be dependent upon NK-1 receptor activation in the VTA. Together, these findings provide evidence for the role of SP and neurokinin receptors in drug relapse.
Soul and society in a technological age, American drama, 1920-1950

Literary scholarship sometimes perpetuates an appearance of a dichotomy between art and technology, despite the fact that both share a similar etymological origin (the Latin 'ars' and Greek 'techne' both mean "skill") and an essential connection. American drama between 1920-1950 explores the inescapable relationship between man and machine, during an age when machines become increasingly domesticated and accepted as an index to the American dream. The marriage between dramatic art and dramatic technology stems not only from the physical realities of staging, but also from the intimate connection of technology with human labor inside and outside of the household (i.e. family, and "career" or employ)--two foci especially prominent in American drama. Technology shapes and defines the values interior to the human soul, individually and collectively (the ' civitas') in addition to producing the external, physical environment in which people live (the 'urbs'). Drawing on the experiments of European Expressionism, especially under acknowledged German models in drama and film, American dramatists found new techniques for developing character and theme, as well as innovative staging techniques. Most important, however, the three decades of drama examined in this study illustrate three progressive stages in the human response to the machine. In the Twenties, O'Neill's The Hairy Ape and Dynamo, Rice's The Adding Machine and The Subway, and Treadwell's Machinal tells stories of self-destructive hostility toward advancing mechanization. In the Thirties, Odets's agit-prop Waiting for Lefty, Hall-Rogers' Federal Theatre production Altars of Steel, and Luce's conservative O! Pyramids illustrate socialized acceptance of the machine, across a wide political spectrum. Finally, in the Forties, Miller's All My Sons and Death of a Salesman, Wilder's The Skin of Our Teeth, and Williams's A Streetcar Named Desire show the deeply intimate penetration of technology into individual and social life, manifesting itself as both an on-stage prop (as a wheel, a light bulb, or a wire recorder), and as an addition to the playwright's arsenal of dramatic tools.
Data spatial aggregation issues in public health analysis, case study for the Toronto's inner city (Ontario)

This study examines the impacts of spatial aggregations of data on the outcomes of univariate and bivariate statistical analyses in an epidemiological context. Health and socioeconomic variables are used to examine a changing interdependency between these two elements at various levels of spatial aggregation. In order to complete these tasks a series of spatial data aggregations (scaling) and regroupings (zoning) are conducted and selected standard statistics are calculated at each of these levels. This study evaluates also the appropriateness of the use of standard statistical units in the settings of public health studies. An overview of selected contemporary issues in spatial statistics and epidemiology precedes the case analysis. The findings of this study reveal that spatial aggregation and rezoning of health and SES data have a substantial influence on the results of statistical analyses. Standard spatial units show less desirable characteristics for the study of the impacts of an income variable on the rates of avoidable hospitalizations than the custom units constructed in this study. These alternative spatial units are proposed as more informative than the standard ones based on comparative statistical outcomes for the area of Toronto's inner city at the neighbourhood level.
A community of voices, a qualitative study of the effects of being a member of the Bell'Arte Singers

This thesis is the story of people who come together regularly to sing; a community of singers who partake in a meaningful artmaking experience. Why do people spend time and money on arts activities when current economic and educational values suggest that other pursuits are more worthy? What can be learned about engagement in arts experiences from this group? Literature and research inform us that the arts are a means of knowing and learning; that they contribute to a culture of permanence; and that they are a means of connecting humans to the world beyond. This study is designed to get at the heart of the experience of the individual singer who belongs to a specific choir. Case study, grounded theory, and narrative inquiry methods were employed, using the ethnographic tools of the video and audio recorded field events, the recorded and transcribed interview, recorded and transcribed focus group interviews, field notes, and questionnaires. The individual voices of the participants were captured, studied, and analyzed, and conclusions in the form of hypotheses were introduced. The data presented themselves in a matrix of layers and clusters. Responses and dialogue were grouped according to a connectedness in meaning and were attached to a framework echoing the parts of the 'musical mass setting '. The clusters of thematically related data formed theoretical constructs and were presented as 'canticles'. The study revealed that participants viewed their participation in the choir as 'Community, Self-identity, Means of Restoration and Healing', and 'Means of Developing Discernment and Connoisseurship'. Dewey reminds us that education, experience, and life are inextricably intertwined. The study of a community of singers yields insights for education. The four emergent constructs provide conditions for quality learning in the classroom ... a school world connected to the real world, where human values, beliefs, attitudes, moral judgment, inclusivity, non-violence, and self-esteem are held in high regard.
Life after Hobbes?, the logic of power from Hobbes to Foucault

How and why did life--that is, biological existence--become not only the central category of modern politics but also the central object of modern power? Hobbes was the first to design a political system joining life with politics. Hobbes argued that the preservation of life was the goal of government and that human physiology was the source of all human behaviour. These two arguments placed life at the centre of modern politics: the authority of government was linked to its ability to protect life; governments became concerned with physiology to understand the causes of, and the ways of influencing, human behaviour. Subsequent political philosophers, such as Bentham, radicalized Hobbes's arguments. Bentham claimed the study of physiology highlighted not only the causes of human behaviour but also how this behaviour could be manipulated and transformed. Bentham's Panopticon was a technology that could, by using the physiological "springs and actions" of human behaviour, disassemble and reassemble the individual. Individuals who represent a threat to the happiness of society as a whole should, Bentham insisted, be subjected to the Panopticon, which would transform them into productive members of society. This technological ability to manipulate life, Foucault later argued, created a "strange logic" at the heart of modern power. The possibility of transforming the dynamics of life produced a continuum from the "normal" to the "pathological"; and individuals were related to political power depending on where they fell within this continuum. The normal individual was held up as the model, and the pathological individual was subjected to treatments that aimed to transform him into a normal individual. If the pathological individual resisted, he was to be destroyed. The destruction of the pathological individual reveals the strange logic of modern power: in the name of life (the normal), governments have the right and the duty to destroy life (the pathological). While Foucault failed to develop a persuasive alternative to this strange logic, he outlined how it has become the most significant problem facing contemporary political philosophy.
Diverse distributions and functions of SPARC during Xenopus laevis early development

SPARC is a highly conserved calcium-binding glycoprotein with dynamic transient patterns of expression during early 'Xenopus laevis' embryonic development. Injection of mature SPARC into the blastocoel cavity of blastula embryos leads to a dose dependent reduction in anterior to posterior structures (ventralization/posteriorization). This phenotype is mimicked by a synthetic peptide (peptide 4.2) corresponding to the C-terminal EF-hand of SPARC. Molecular and morphological studies indicate that SPARC induces involuting chordomesodermal cells to round up, reducing their posterior to anterior migration. This activity on cell-matrix interaction provides the first 'in vivo' evidence of a counter-adhesive activity for SPARC. Although SPARC has been characterized as a secreted extracellular matrix (ECM) glycoprotein, whole mount immunocytochemical analysis indicated that SPARC is associated with cilia of the embryonic/larval ectoderm of ' Xenopus'. SPARC is concentrated in the outer surface layer, particularly in cilia. Immunogold electron microscopy shows that SPARC is associated with the 9 + 2 microtubule arrays of the ciliary axonemes. Tubulin can be immunoprecipitated with antibodies that cross-react with 'Xenopus' SPARC, indicating a direct or indirect interaction of SPARC and tubulin. SPARC is also concentrated circumferentially at the apicolateral plasma membranes of surface ectodermal cells. Injection of anti-sense 'Xenopus ' SPARC morpholinos leads to the dissociation of surface ectoderm by mid-tailbud. A similar dissociation is observed with animal cap explants taken from morpholino injected embryos. These studies indicate that SPARC promotes epithelial cell-cell adhesion and is required for maintaining the integrity of the embryonic epidermis of 'Xenopus' embryos. This represents the first evidence of an adhesive function for SPARC. Collectively, my studies indicate that SPARC functions intracellularly as a calcium-dependent regulator of ciliary movement and that SPARC has adhesive activity in epithelial tissues, in contrast to an anti-adhesive activity in mesenchymal tissues. Since the associations of SPARC with cilia and circumferential enrichment are observed in amphibians and mammals, it is likely that these intracellular and extracellular functions of this glycoprotein are evolutionarily conserved.
Understorey vegetation of carefully-logged boreal forests in northeastern Ontario

Unconstrained ordination (DCA) on 604 stands of combined vegetation data from independent surveys, including post-fire, post-clear-cut and carefully-logged boreal forest understorey communities, showed primary trends associated with soil nutrient and moisture regimes. Clear-cut stands appeared to represent a change in community/ecosystem characteristics from the pre-logged condition. Understorey vegetation of the carefully logged stands were similar to postfire oligotrophic forests. Among the 48 carefully-logged stands only, canonical correspondence analysis (CCA) and partial (P)CCA confirmed the primary importance of soil nutrient and moisture conditions. PCCA indicated that the level of canopy retention, the extent of canopy removal, post-harvest herbicide treatment and age since harvest were minor contributors to the overall plant community variability among stands. Clear-cutting disrupts the forest floor, changes the soil conditions and precipitates community change. Careful-logging, when carried out only in winter, retains the integrity of the organic forest floor. Consequently, no detectable understory plant community change ensues.
Characterization of an early senescent mutant in Arabidopsis thaliana

In an attempt to elucidate the mechanisms of CO2-mediated regulation of gene expression in plants, 10 to 14 day old T-DNA mutagenized Arabidopsis thaliana seedlings grown at ambient levels of CO2 were exposed to elevated CO2 conditions of 3000 ppm for four days. Plants exhibiting a phenotype that deviated from the wild type response in elevated CO2 conditions were placed in two broad categories: insensitive and hypersensitive plants. The hypersensitive plants were further subdivided by phenotype and one mutant exhibiting e_arly s_enescence of c_otyledons ('esc'1) was chosen for further study. The 'esc'1 mutant exhibits accelerated senescence of its cotyledons, is short in stature, and develops undulated, epinastic leaves. The mutation was not found to be closely linked with the T-DNA insertion; therefore, genetic mapping was used to identify the location of the mutation. The mutation was fine mapped to Chromosome I using molecular markers and was found to be near the G4026 marker. Structural analysis of tissue sections of the mutant with light microscopy and SEM suggested that the cells in the cotyledon appear to have collapsed prematurely. Biochemical analysis of the mutant indicated a decrease in the amount of chlorophyll and total carbohydrate levels were increased in the ' esc'1 cotyledons. Moreover, as the mutant phenotype is not rescued in ambient (360 ppm), or low (150 ppm) CO2 concentrations, it is believed that elevated levels of CO2 affect the ontogenic rate of development. Therefore, the 'esc'1 plant may not be directly involved in a CO2-mediated gene expression pathway. The mutant foliar phenotype was restored to a wild type phenotype when grown in the presence of 3% sucrose, but similar levels of glucose did not appear to rescue this mutant. In an attempt to isolate additional genes involved in this phenotype, a second mutant screen was performed. Six putative positives were identified in a tertiary screen. Of these six putative mutants, one appeared to have its phenotype rescued when grown on 3% sucrose, and thus may be allelic to the 'esc'1 locus. Taken together, these phenotypes suggest that the mutation has altered a process in carbohydrate transport or allocation, which results in accumulation of total carbohydrates in the cotyledon. This accumulation may repress photosynthetic genes, thereby prematurely initiating senescence of the cotyledons. The modified transport or allocation of carbohydrates is suggested here to cause the epinastic and deformed true leaves.