VictorJuiz/thesis huggingface dataset:
Determinants of Working Memory Performance
Keywords: working memory
age differences
interference
practice effects

This dissertation investigated different factors contributing to age differences in working memory (WM) performance. Younger and older adults participated in five experiments, four on visuospatial WM (VSWM) and one on verbal WM. All addressed methodological issues that may differentially lower older adults’ performance. Experiments 1a and 1b manipulated the administration of a VSWM span task, with participants performing the task under either an ascending format (shortest sets presented first), or an interference-reducing descending format (longest sets presented first). Older adults’ performed significantly better in the descending compared to ascending format, consistent with an age-related susceptibility to proactive interference (PI). By contrast, younger adults did better in the ascending compared to descending condition, possibly due to their ability to benefit from practice and strategy use when easier trials are presented first. Experiment 2 considered how the similarity of task material influenced the build-up of PI and whether or not the combination of two PI-reducing manipulations (i.e., descending format and distinct trials) would further improve older adults’ performance. Distinctiveness helped older adults on the ascending format; however, combining distinct trials and a descending format provided no additional benefit. Experiment 3 considered whether or not synchronizing a VSWM task with an individual’s circadian arousal pattern would moderate interference effects, with the task administered at a peak or off-peak time of day. Peak-time administration improved older adults’ performance on the descending, but not the ascending, condition. Experiment 4 investigated the possibility that the serial order requirement of many WM tasks contributes to age differences in performance. Younger and older adults participated in a verbal WM span task – Operation Span - under either serial order or free recall instructions. Typical age differences were found when order but not free recall was required. Further analyses of the order condition data revealed that older adults were, in fact, recalling the items just as well as young adults, only not in the correct order. Taken together, the findings strongly suggest that age differences found on typical WM span tasks are influenced by numerous factors, such as task presentation, individual circadian arousal patterns, material similarity, and recall instructions.
Camping at the Caribou Crossing: Relating Palaeo-Eskimo Lithic Technological Change and Human Mobility Patterns in Southeastern Victoria Island, Nunavut
Keywords: Palaeo-Eskimo
Lithic Technology

This dissertation explores the inter-relatedness of lithic technology and human mobility in the ancient central North American Arctic. Palaeo-Eskimo populations inhabited southeastern Victoria Island, Nunavut, discontinuously for over three thousand years. During this time, Palaeo-Eskimo lifeways are believed to have changed significantly in regards to subsistence economy, settlement patterns, interaction patterns, and mobility. One of the most significant changes is a marked decrease in the scale and frequency of human mobility and an increase in the re-occupation of seasonal camps. Palaeo-Eskimo material culture is observed to undergo important changes at the same time; consequently, one wonders what influence(s) mobility may have effected on the form and nature of Palaeo-Eskimo material culture. This work examines the potential influence of human mobility on lithic technology in the Pre-Dorset, Early Dorset, and Middle Dorset periods as evidenced by lithic assemblages from nine archaeological sites and site components in the Iqaluktuuq (Ekalluk River) region of Victoria Island. Over 800 formal tools and 30000 pieces of debitage were examined and analyzed according to two interpretive frameworks: one technological and the other mobility-related. The technological analyses demonstrate that significant changes took place in lithic production and maintenance processes during the Palaeo-Eskimo period. The mobility-related analyses demonstrate that, while many of the changes to lithic technological organization are consistent with expected trends resulting from a decrease in human mobility, not all aspects of Palaeo-Eskimo lithic tool production, maintenance and use appear to have been similarly influenced by this change in mobility.
Molecular Mechanisms Regulating Neurite Growth, Innervation and Survival
Keywords: dendrite
axon
neuron
degeneration

The establishment of correct neural circuitry in the nervous system requires the interplay, integration, and coordination of a diverse set of cells and signals during development and in the adult. Two important events are the regulated initiation and growth of dendrites that receive and process synaptic information, and the establishment and maintenance of appropriate neural connectivity. The goals of this study are to identify the molecular mechanisms underlying dendrite growth and initiation, and to understand how neural connectivity is maintained in the adult nervous system. I first identified a novel intracellular signal transduction pathway involving two kinases important in regulating dendrite development. I showed that the ILK-GSK3beta pathway is required for dendrite growth and initiation in both peripheral and central nervous system neurons. I then asked how neural connectivity is maintained in the adult nervous system by examining the role of myelin in the intact nervous system. My results indicate that when myelin contacts aberrantly growing axons, it activates on those axons the p75 neurotrophin receptor (p75NTR), which in turn causes the local degeneration of those axons. I further identified the signal transduction pathway required for axon degeneration consisting of p75NTR and intracellular signaling proteins activated by this receptor, Rho-GDI, Rho, and caspase 6. This data establishes p75NTR as an important regulator of neural connectivity and identifies for the first time a degeneration-inducing signal transduction pathway activated by myelin. It also provides an explanation for why myelin inhibits regeneration of injured central nervous system axons. Taken together, I identified a new signaling pathway important for regulating dendrite initiation and growth, and a novel role for myelin in maintaining neural connectivity. Both of these findings contribute to our knowledge of how such connectivity is established during development and maintained in the adult nervous system.
Geometric Theory of Parshin Residues
Keywords: Complex Algebraic Geometry
Singularity Theory
Multidimensional Residues
Stratified Spaces

In the early 70's Parshin introduced his notion of the multidimensional residues of meromorphic top-forms on algebraic varieties. Parshin's theory is a generalization of the classical one-dimensional residue theory. The main difference between the Parshin's definition and the one-dimensional case is that in higher dimensions one computes the residue not at a point but at a complete flag of irreducible subvarieties. Parshin, Beilinson, and Lomadze also proved the Reciprocity Law for residues: if one fixes all elements of the flag, except for one, and consider all possible choices of the missing element, then only finitely many of these choices give non-zero residues, and the sum of these residues is zero. Parshin's constructions are completely algebraic. In fact, they work in very general settings, not only over complex numbers. However, in the complex case one would expect a more geometric variant of the theory. In my thesis I study Parshin residues from the geometric point of view. In particular, the residue is expressed in terms of the integral over a smooth cycle. Parshin-Lomadze Reciprocity Law for residues in the complex case is proved via a homological relation on these cycles. The thesis consists of two parts. In the first part the theory of Leray coboundary operators for stratified spaces is developed. These operators are used to construct the cycle and prove the homological relation. In the second part resolution of singularities techniques are applied to study the local geometry near a complete flag of subvarieties.
Beyond the Work Trip: Teen Travel in the Greater Toronto Area (GTA) and Policy Implications
Keywords: travel behaviour
urban form
public transit
teenagers

Conventional transportation demand management approaches have had limited success in reducing automobile dependency. As a result, it has become increasingly important to understand the decision-making processes involved in determining travel behaviour. The purpose of this dissertation is to extend research on urban form and travel behaviour beyond adult travel by examining teen travelers aged 13-19 in the Greater Toronto Area. Data from the Transportation Tomorrow Survey (TTS) survey are used to study four main research questions: 1) How has teen mode choice changed from 1986 to 2006? 2) How do these choices vary as teens transition from the 13-15 age group to being of driving age (16-19)? 3) How do these choices vary across the different urban and suburban regions of the GTA? 4) What are some of the differences between teen travel and adult travel? The issue is further probed through the collection of quantitative and qualitative travel data from first year students at the University of Toronto, and a series of focus groups held in locations in the GTA. The first year survey explores attitudes towards different modes in relation to the locational attributes of the respondent‘s hometown neighbourhood. The focus group sessions involve interviews with 26 teen and a take-home parental questionnaire. Results show that across the GTA, active transportation has decreased while auto passenger mode shares have increased. Younger teens walk more and older teens take transit more for both school and discretionary travel. Jurisdictions with better transit supply and orientation have higher transit mode shares for school trips, but discretionary trips have low transit mode shares. Walk mode shares for both school and discretionary travel are similar across all jurisdictions, regardless of whether they are urban or suburban. Additionally, the survey participants' narratives illustrate that the desire to travel actively and independently is strong. However, the reality of the final travel choice is determined by the presence of supportive infrastructure that facilitates active mode choices while shaping perceptions and attitudes formed as a result of daily travel experiences. Findings illustrate the relevance of qualitative work in advancing transportation research--particularly in understanding human travel decisions.
Bioengineering of a TAT-conjugated Peptide to Modulate the Activity of Glycogen Synthase Kinase-3 in Adult and Embryonic Stem Cells
Keywords: glycogen synthase kinase-3
cell-permeable peptide

The intracellular delivery of molecules to modulate signaling pathways and gene expression is a powerful approach to control stem cell fate decision. For applications in gene therapy and regenerative medicine, the use of genetic material and viral vectors raise concerns because stem cells persist throughout life, and long-term effects of uncontrolled genetic modifications could affect the cellular progeny. An alternative is to deliver directly peptides or proteins using cell-permeable peptides (CPPs) which have the ability of crossing the plasma membrane and carrying cargos into cells. CPPs can therefore be used to deliver factors to direct stem cells proliferation, survival and differentiation. This thesis describes an approach to control stem cell fate based on the delivery of a CPP-conjugated bioactive peptide. A first significant contribution from this work is the development of a flow cytometric assay to accurately quantify the uptake of a panel of CPPs. This study revealed that HIV-transactivator of transcription (TAT) and Antennapedia (Antp) offered the highest level of translocation in different cell types. The uptake was improved by treating the cells with a single, low-voltage electrical pulse that selectively enhances the amount of TAT-conjugated peptides and proteins delivered by at least an order of magnitude, without causing cellular toxicity or apoptosis. Subsequently, flow cytometry, confocal microscopy, capillary electrophoresis and mass spectrometry were used to examine the intracellular fate of TAT-conjugated peptides in order to define the parameters that limit their bioactivity and point to specific sequence modifications that can improve their efficacy. The advances described in this thesis were applied to the development of TAT-eIF2B, a peptide-inhibitor of glycogen synthase kinase-3 (GSK-3). TAT-eIF2B was found to be specific for GSK-3 and had a significant positive effect on the formation of neurospheres in embryonic stem cell cultures and on the survival of myeloid progenitors in cytokine-starved fetal liver cell cultures. On the other hand, GSK-3 inhibition reduced the number of neurospheres generated by human olfactory neuroepithelium cells due to lower proliferation and increased neuronal differentiation. In summary, this work describes the development of a peptide-based technology to deliver bioactive cargoes in cells, and it demonstrates its utility for modulating the activity of a master regulator of stem cell fate decision.
The Rooster's Egg: Maternal Metaphors and Medieval Men
Keywords: Medieval History
Medical History
Gender History

The present study explores representations of the female reproductive body in medieval written sources, with an emphasis on the figurative language that was used to describe pregnancy, childbirth, menstruation, and lactation when these phenomena take place in the female body and, symbolically, in male bodies. This examination of what are herein labeled “maternal metaphors” in men, that is a comparison between a male subject and an attribute specific to women’s reproductive bodies, reveals how anatomical and physiological characteristics exclusive to the female reproductive body were used to convey descriptive meaning, and considers why and in what contexts such comparisons were made. This study looks at ancient and medieval medical writing, biblical and medieval Christian religious sources, and various other texts taken from medieval secular and popular literature, where maternal metaphors were used to describe other anatomical and physiological phenomena that were not specific to women, physical and behavioural characteristics of male subjects, and intangible qualities of divine persons. This thesis argues that the female body was the site of diverse conceptual associations in medieval medical and religious traditions, and that, as a result, it proved to be a significant source for figurative analogies that could convey similarly wide-ranging meanings. When pregnancy, childbirth, menstruation, and lactation were used metaphorically to describe male subjects, the variety of connotations that were transferred reflects the range of possible meanings; however, the complexity is not transmitted. Maternal metaphors in men convey meanings that are either good or bad, or occasionally neutral, depending on the context and subject.
Foreign Equity Portfolio Flows and Local Markets: Two Examples from the Istanbul Stock Exchange
Keywords: International Finance
Empirical Asset Pricing

This thesis analyzes the nature of foreign equity trades in relation to their effects on local markets. My goal is to contribute to the understanding of equity flows of foreign investors and their effect on the local markets. The thesis consists of two chapters, both of which employ a novel data set that is consisted of monthly equity flows by foreign investors at Istanbul Stock Exchange of Turkey. The first chapter, Foreign Ownership and World Market Integration, aims to explain the de facto financial market integration with global markets with foreign equity ownership using a novel data set of foreign portfolio flows at the individual stock level. The main result is the positive link between global nancial integration and past portfolio in flows by foreign investors on the cross-section of local stocks. The results have high economic significance: Across individual stocks a 1.4% increase in foreign portfolio inflows corresponds to up to 3.3% greater relative explanatory power of the global factor in explaining local stock returns in the following month. The results are indicative of a causal link: The lead-lag effect between foreign portfolio inflows and financial integration does not exist in the opposite direction. I show that stocks that experience an increase in foreign ownership are not more financially integrated in the past, i.e. the foreign portfolio flows are not a response to increased financial integration. The second chapter is titled as Uninformed Momentum Traders and it studies the relationship between momentum trading and information. I present evidence that supports the hypothesis that momentum trading is linked to a lack of information. I document significant momentum trading by foreign investors in stocks on which they potentially have more informational disadvantages. Small stocks, stocks with high volatility and low liquidity, stocks that are financially less integrated and have greater foreign exchange risk are subject to greater momentum trading. Moreover, stocks on which foreign trades indicate lower future profitability are subject to higher momentum trading. Additionally, I show that momentum trades by foreign investors exert contemporaneous price pressure and have no valuable longer-run information content. The contemporaneous price pressure of 2.30% per month is followed by a significant return reversal in the following two quarters. Finally, there is strong evidence that foreign investors do not possess local market speci c information. Momentum trading by foreign investors is triggered by the past profitability of the momentum factor in the local market. However, the negative pro tability of momentum makes momentum trading a sub-optimal trading strategy.
Between Myth and Meaning: The Function of Myth in Four Postcolonial Novels
Keywords: English Literature
Postcolonial fiction

In Anglophone postcolonial fiction of the twentieth century, myth is used as a framing device that contains and interrogates historical event, thereby functioning as a form of alternative history. Despite the prevalence of cross-cultural symbolic systems and radically hybrid forms of narration, the dominant method of reading myth in postcolonial literary criticism remains dependent on conceptual models that construct myth as originary racial narrative. This particular approach fosters readings of contemporary secular myths of “nation”, “land” or “identity” within culturally monolithic frames. I scrutinize the intersections between early structuralist approaches to myth, and later post-structuralist deconstruction of myth and suggest a postcolonial reading of myth as the ideological coded middle space between sacred and secular narrative. Focusing on four novels from Southeast Asia, South Asia and the Caribbean, I demonstrate the continued influence and adaptability of myth to narrate vastly different historical and socio-cultural contexts. Taking into account several major shifts in the conceptualization of twentieth-century myth criticism , I develop a critical vocabulary for comparative readings of myth which interrogates existing discourses on the categories of “archetype”, “ideology” and “symbol”. My approach is comparativist, and foregrounds the importance of locating myth within literary and socio-cultural context. The introduction to this study defines the field of myth criticism in relation to postcolonial fiction. I provide outlines of the theoretical positions drawn from Carl Gustav Jung, Roland Barthes, Northrop Frye and Bruce Lincoln and demonstrate the relevance of each in relation to reading myth in the four novels under survey. The first chapter looks at the way Alfred Yuson exposes mythic constructions of Filipino identity in The Great Philippine Jungle Energy Café (1987). The second chapter provides a comparative study of Michael Ondaatje's The English Patient (1992) and Allan Sealy's The Everest Hotel A Calender (1998). This chapter analyzes Ondaatje and Sealy's employment of the Fisher King myth as a device for narrating radically different visions of postcolonial community. The third chapter analyzes the function of archetype as a vehicle for ideology in Wilson Harris's Jonestown (1996). The conclusion of this study suggests the way this method of analysis can provoke further critical inquiry in the field of postcolonial myth criticism.
Large-scale and Microphysical Controls on Water Isotopes in the Atmosphere
Keywords: stable water isotopes
climate modeling
paleoclimate
water vapor
precipitation
atmospheric transport

The isotopic composition of water in the atmosphere is influenced by how the water evaporated, how it was transported, and how it formed in the cloud before falling. Because these processes are temperature dependent, the isotopic ratios stored in glacial ice and other proxy sources have been used as an indicator of pre-instrumental climate. There is uncertainty, however, as to whether isotopic ratios should be interpreted as a proxy of local temperature, or as a broader indicator of changes in how the vapor was transported. To better understand these processes, the NASA GISS general circulation model (GCM) was used to examine two different types of controls on the isotopic composition of moisture. The first control was the large-scale circulation of the atmosphere. Over Europe, it was found that δ18O is strongly controlled by a Northern Annular Mode-like pattern, detected in both the GCM and for Europe’s high-quality precipitation δ18O data. Over the southwest Yukon, it was found that higher δ18O was associated with moisture transport from the south, which led to a re-interpretation of the large mid-19th century δ18O shift seen in the ice cores from Mt. Logan. The second type of control was microphysical, relating to the way precipitation interacts with vapor after it has formed. Using a GCM sensitivity experiment, the effects of ‘post-condensation exchange’ were found to depend primarily on the proportion between the amount of upstream precipitation that fell as rain and the amount that fell as snow, and at low latitudes, on the strength of atmospheric moisture recycling. This led to a partitioning of the well-observed correlation between temperature and precipitation δ18O into its initial and post-condensation components, and a GCM-based interpretation of satellite measurements of the isotopic composition of water vapor in the troposphere.