52 research outputs found
Exploratory analysis of functional connectivity using non-invasive electrophysiological recordings
No full textThis thesis addresses a specific problem of functional connectivity analysis from noninvasive electrophysiological recordings; namely, the automatic identification of highly connected cortical regions based on the strength of a study-specific metric. One particular approach developed in this thesis depends on a general, iterative, multi-resolution procedure applied to distributed source imaging constrained to a cortical surface mesh. Additional work was invested towards implementing an intuitive 3D functional connectivity visualization tool that efficiently represents functional connectivity links between regions as virtual white-matter tracts. The last section of this thesis presents results on the study of specific oscillatory phenomena in the visual cortex related to attention, providing evidence of the intricate link between anatomy and functional measurements. Quantitative and qualitative evaluation shows that the 3-D visualization and iterative connectivity imaging procedures can be used to accelerate and facilitate whole-brain connectivity analysis. Results on the influence of anatomical connectivity features on functional measurement in healthy aging are also presented. In agreement with earlier studies,our data demonstrate that basic components of the brain's oscillatory activity are agedependent, including an unexpected dependence of frequency-specific neural signal power with age. Overall, our findings are compatible with the hypothesis of decreased synchronization between hemispheres with age. We show that these results correlate with MRI diffusion-weighted measures between bilateral associative visual regions inter-connected via the corpus callosum. We conclude this experimental section by claiming that coupling between visual regions becomes compromised during healthy aging.Ce travail aborde un problème particulier de l'analyse en connectivité fonctionnelle à partir de données M/EEG, et plus précisément l'identification automatique de régions hautement connectées dans le cadre d'un paradigme experimental donné et de métriques de connectivité fonctionnelle imposées. Une première approche développée dans le cadre de cette thèse se base sur une procédure globale, itérative et hiérarchique appliquée à une reconstruction de sources de signaux M/EEG contrainte à la surface corticale. Des travaux supplémentaires ont été menés afin d'implémenter un module logiciel de visualisation en 3D représentant efficacement et intuitivement des fibres de matière blanche virtuelles. Finalement, ce travail présente des résultats qui contribuent à une meilleure comprehension du lien possible entre anatomie et fonction, notamment la synchronization de phénomènes oscillatoires dans le cortex visuel. Nous détaillons également des résultats concernant le lien entre anatomie et les phénomènes oscillatoires cérébraux. En accord avec d'autres études, nos données montrent l'existence d'un lien entre la fréquence d'oscillation et l'âge des participants, et indiquent une tendance positive entre la puissance des oscillations cérébrales et l'âge. Ce travail démontre qu'il existe que la réduction de la synchronization entre hémisphères est corrélée à la connection anatomique mesurée en IRM de diffusion entre les regions associatives du cortex visuel connectées via le corps calleux
The TCU Lima manuscript: images as testament of validity and innovation
No full textCreated in 17th century Lima, Peru and composed of 366 folios, the TCU Lima Manuscript is a compendium of documents created at different times and by different hands, bound together as proof of pure lineage and nobility of Don Marcelo de Ayala Marin Benavidez y Arce. While primarily alphabetic, the manuscript also includes extensive imagery. The first 92 folios are filled with calligraphic renditions of animals, both real and fantastical, while another 100 folios include exquisite ink drawings of print-like quality and depicting a variety of subject matter including cityscapes and landscapes. In this thesis I will analyze the relation and conflation of word and image. I will focus on imagery in two sections meant to prove what the Spanish referred to as limpieza de sangre, or purity of blood, a concept that took precedence in the Spanish colonies. While the images are not necessarily related to the text, they work on a more symbolic level, with the conflation of word and image serving as a mechanism to prove Don Marcelos claim to noble title. At the same time, they also represent the ingenuity of draftsmen in the New World. My first chapter will introduce the TCU Lima Manuscript and the context of its creation. I will analyze how limpieza de sangre functioned as a juridical category and the institutional, legal, and archival mechanisms that helped reproduce the purity of blood discourse in Peru, leading to the creation of documents such as the TCU Lima Manuscript. Chapter two and three focus on the imagery in first section and the penultimate section of the manuscript respectively. These two chapters examine the proliferation of European imagery and the adoption, conflation, and reproduction of imagery in the New World, particularly in terms of workshop tradition and creative efforts by New World artist to create their own styles
Persistence of soil moisture in the Cariboo Mountains, British Columbia.
No full textIn the Cariboo Mountains of British Columbia, nearly 50% of the annual precipitation falls as snow. Over the winter, snow accumulates, is redistributed and metamorphoses until temperatures warm and the spring melt begins. In about 2-3 weeks, the water stored in the seasonal snowpack is released at the surface to infiltrate the soil and runoff into local streams and rivers. Soil moisture is an integral component of the hydrologic cycle and knowing the contribution and persistence of soil moisture from snowmelt is important to understanding the local hydrology. Here are presented hydrometeorological data spanning from 17 July 2008 to 14 July 2009 from a cut-block site in the Mt. Tom Forest Management Area, south east of Prince George, British Columbia. Data from this period are compared to the 1971-2000 climate normals at Barkerville. The winter of 2008-2009 saw higher than average snowfall with average monthly snowfall of 58 cm compared to 44 cm for 1971 to 2000. Maximum accumulation reached 156 cm on 2 April 2009. Temperatures for the 2008 to 2009 season were cooler than average (1.9°C) at both Mt. Tom (0.4°C) and Barkerville (0.7°C). There are no long term data available for Mt. Tom so climate comparisons are based on data collected at Barkerville. Persistence of soil moisture has implications for plant and tree growth as well as for the length of the work season for industry. With increased industrial activity and the current mountain pine beetle problem in the Cariboo region, it is likely that this area will undergo significant deforestation in years to come. Coupled with a wetter climate, as projected by climate change analysts, the capacity of the soil to retain water could become more important when trying to reduce impacts of industry, such as erosion and compaction of soil. --P.iiThe original print copy of this thesis may be available here: http://wizard.unbc.ca/record=b173787
Trends and elevational dependence of the hydroclimatology of the Cariboo Mountains, British Columbia.
No full textPristine mountain environments are more sensitive to climate change than other land surfaces. The understanding of climatic variations in mountainous terrain is still uncertain. Previous studies reveal inconsistent findings on the elevational dependency of warming in the mountains. In this study, the trends and elevational dependence of climatic variables in the Cariboo Mountains Region (CMR) of British Columbia are explored. A high resolution 10 km x 10 km gridded data set of climate variables over the period of 1950-2010 is used. The Mann-Kendall test is performed for evaluation of trends and their significance. The CMR is warming at a faster rate in recent decades than regional and global warming. The minimum air temperature trend shows significant amplified warming at higher elevations. Precipitation does not show any significant trend across the study area. The possible physical mechanisms for such warming trends and the potential impacts of these changes on the endangered mountain caribou and water resources of the area are discussed. --Leaf i.The original print copy of this thesis may be available here: http://wizard.unbc.ca/record=b197643
Characterization of regional air temperature and precipitation and its relationship to shallow groundwater resources in the ancient forest, British Columbia.
No full textIn the Inland Temperate Rainforest (ITR) of northeastern British Columbia, nearly 50% of the annual precipitation falls as snow. Persistence of soil moisture has implications for tree species survival and snowmelt is a vital component of the soil moisture regime in the ITR. Presented in this study are hydrometeorological data from 1 November 2011 to 31 August 2012 from two sites, the Ancient Forest and Lunate Creek, 110 km east of Prince George, British Columbia and are compared to the 1981-2010 climate norms at Prince George Airport. Shallow groundwater, surface water, and seasonal precipitation were collected for isotopic analysis to identify moisture sources for shallow groundwater. Soil moisture and shallow groundwater had minimal response to rainfall, but snowmelt comprises 40% of shallow groundwater. With changes in climate indicating a phase shift from snow to rain, the snowmelt contribution to groundwater, and thus available soil moisture, has the potential to diminish. --Leaf ii.The original print copy of this thesis may be available here: http://wizard.unbc.ca/record=b200683
Assessment of optimum snowmelt model complexity, Cariboo Highlands, British Columbia, Canada.
No full textThe goal of this study is to assess the performance of melt models of varying complexity to simulate snowmelt under different aspect, forest cover, and input data conditions in the British Columbia interior. Observed snow water equivalent data from the 2008 melt season were used to compare the performance of a basic temperature-index (TI) model, three modified TI models, and a simple energy balance model (EBM). The largest (smallest) values of NSE (RMSE) for the snow course sites were 0.81 (0.0243 m) for the TI models and 0.58 (0.0362 m) for the EBM. At the automatic snow pillow (ASP) the largest (smallest) values of NSE (RMSE) were 0.54 (0.0055 m) for the TI models and 0.65 (0.0048 m) for the EBM. At the snow course sites all TI models performed better than or equivalent to the EBM. At the ASP one EBM version performed better than the TI models. --P.ii.The original print copy of this thesis may be available here: http://wizard.unbc.ca/record=b173648
Pragmatism, projections, priorities, plans and politics in Prince George: Adapting to climate change in a Canadian community.
No full textThe two principal human responses to climate change are adaptation and mitigation. A small, but growing, number of scientific and professional efforts are focusing toward adaptation, as it becomes clear that mitigation efforts alone can no longer effectively minimize the negative impacts of climate change. Local governments are well suited to undertake proactive adaptation measures due to their abilities to apply social capital, act quickly, and implement actions that can provide direct benefits for residents. Like many northern communities, the City of Prince George, Canada, has been experiencing rapid rates of climate change. City practitioners have been responding to changing conditions in the region for years, and expressed interest in formally exploring adaptation with researchers. During a focused one-day workshop, an overview of climate change and past climate trend and future projection information were presented to local staff and stakeholders, and applied to determine impact priorities. The workshop outcomes were triangulated with community feedback to create an adaptation strategy for Prince George. Changes to forests and increased flooding are the top local priorities, and impacts related to transportation infrastructure, severe weather and water supply are high priorities. Other impacts, such as agricultural changes, are important but did not rank highly using a risk assessment framework. The adaptation strategy precipitated further local engagement and action. Researchers participated in the processes to create a sustainability plan and update the Official Community Plan for Prince George. Many adaptation measures were integrated into both documents. Factors enabling the incorporation of adaptation included the high level of local knowledge and existing adaptation strategy. Many barriers, including limited policy direction and a lack of priority, continue to pose challenges in mainstreaming adaptation into local plans. Additional research focused on forests, flooding, transportation infrastructureThe original print copy of this thesis may be available here: http://wizard.unbc.ca/record=b189094
Remote sensing of snow and its application to hydrometeorological studies in western Canada.
No full textSnow plays a vital role in the energy and water budgets of drainage basins of western Canada. Various remote sensors such as Moderate Resolution Imaging Spectroradiometer (MODIS), Advanced Microwave Scanning Radiometer (AMSR-E) and Special Sensor Microwave/Imager (SSM/I) have been launched to map the snow cover extent (SCE), snow cover fraction (SCF), and snow water equivalent (SWE) across the globe. However, the distribution and variability of snow inferred from remote sensing products have not been comprehensively investigated in western Canada owing to its complex topography and harsh environment. So far, little research has been conducted on SCE-streamflow and SCE-SWE-runoff models focusing on Canadian watersheds where snow cover is very important for human well being. Although microwave remote sensing of snow is widely developed and applied in Canada, the retrieval of SWE in western Canada is not as well established owing to the complex topography in this area. Therefore, the Quesnel River Basin (QRB) of British Columbia is selected as a primary test site to develop and test SCE-streamflow and SCE-SWE-runoff models. Then the Mackenzie River Basin (MRB) is chosen as a secondary test site to apply the Environment Canada (EC) SWE retrieval algorithms to upscale the hydrometeorological research. In this thesis, a new approach referred to as the spatial filter (SF) method is developed to decrease the cloud coverage in the MODIS snow products. At the same time, the new snow products are evaluated based on in-situ observations of snow depth in the QRB. Then the relationships between SCF from MODIS, topography, and hydrometeorology of the QRB are explored. In addition, various retrieval algorithms of SWE from microwave remote sensing are tested in the QRB. At last, the Environment Canada algorithms of SWE from SSM/I are adopted to produce new SCF products evaluated with the MODIS snow products. The relationships between SWE and SCF from SSM/I and hydrometeorology are also investigated in the MRB ...The studThe original print copy of this thesis may be available here: http://wizard.unbc.ca/record=b164706
Parental Involvement in Title I Schools: Examining Perspectives of Parents & Teachers
No full textabstract: ABSTRACT
Parental involvement is vital to student success academically as well as socially (Jeynes, 2007; Kim & Hill, 2015). The purpose of this mixed-methods action research study was to examine the perceptions of parental involvement of parents and teachers in a Title I school. A training session intervention, Social Hour, was designed using the Heath and Heath change model (2010) to create an opportunity to learn about parental involvement and educate the school community on the Epstein’s six-types of parental involvement (Epstein, 1987). The goal of the Social Hour workshop was to address the challenges and barriers to parental involvement, previously listed in the literature. Using the lens of Critical Race theory (Blalock, 1967) ensured that the research gives a voice to those who are often marginalized while also helping parents and teachers build a relationship of trust and understanding using principles of Community of Practice (Wenger, 2009). The results of this study indicate that Social Hour-type learning events are significant in the change to perceptions of parental involvement. The participants had a lower level of confidence at the beginning of the session than at the end. Additional qualitative results also suggest a change in attitude after attending the Social Hour. Participants noted they had more energy about parental involvement and were encouraged that parental involvement does not require them to volunteer more; that it is more about being engaged in their child’s education. Overall, participants reported an increase in confidence and had a positive view of parental involvement based on attending the Social Hour workshop.
Keywords: Parental involvement, Critical Race theory, Epstein Six Types of Parental involvementDissertation/ThesisDoctoral Dissertation Leadership and Innovation 202
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