VictorJuiz/thesis huggingface dataset:
Relationships Between Operating Conditions, Carbon Deposition, and Performance in Solid Oxide Fuel Cells
Keywords: solid oxide fuel cell
coking, carbon deposition

This research examines the effect of solid oxide fuel cell (SOFC) operating conditions on carbon deposition in nickel/yttria-stabilized-zirconia (Ni/YSZ) anodes and the effect of carbon deposition on impedance spectra of polarized SOFCs. Although Ni/YSZ anodes are susceptible to degradation from carbon deposition, Ni/YSZ is still a competitive material set compared to coke-resistant alternatives due to its relative cost and elemental abundance. Thus, it is important to more clearly define coking thresholds with respect to temperature (T), molar steam:carbon ratio (SC), fuel utilization (Uf ), current density (i), and mole fraction of ethane in the fuel (fC2H6). The quantification of gasified carbon (QGC) method was developed for in-situ measurement of carbon deposition on operating SOFCs. Deposited carbon is gasified with H2O, and carbon mass is measured by quantification of evolved CO. It was shown that deposited carbon can be gasified after 100 hours residence time. The accuracy of the QGC method was validated using a thermogravimetric analyzer. Carbon deposition thresholds were measured on button cells with 10 hour carbon deposition periods using CH4 reformate gas mixtures. The constituent concentrations of CH4 reformate gas mixtures were developed mathematically for different SC and Uf. Homogeneous decomposition of C2H6 convolutes carbon mass measurements and limited the study of fC2H6. The coking threshold at open circuit in the SC domain (Uf = 0) was measured to be approximately 1.04 and 1.18 for 600 and 700°C, respectively. The coking threshold at open circuit in the Uf domain (SC = 0.03) was measured to be approximately 36% and 32% for 600 and 700°C, respectively. Coking thresholds agree well with thermodynamic equilibrium calculations when the properties of solid phase carbon are modified appropriately. This observation was further supported by experiments with varying current density. Using measured coking thresholds, the Gibbs free energy of carbon on Ni/YSZ cermets at 600°C was calculated to be 6.91±0.08 kJ-mol-1. Coking on a polarized SOFC was found to be minimally detectable by impedance spectroscopy. The results from this work can be readily applied to SOFC system design, numerical simulations of SOFC anodes, and design of anodes with material gradients.
Structural and Functional Characterization of the Essential AAA+ ATPases Rvb1 and Rvb2 of S. cerevisiae
Keywords: ATPases
DNA

Rvb1 and Rvb2 are essential proteins of the AAA+ superfamily of ATPases associated with a diversity of cellular activities. The Rvbs are components of several chromatin remodeling complexes and the R2TP complex, which is involved in the assembly of small nucleolar ribonucleoprotein complex, RNA polymerase II, Telomerase complex, and Phosphatidyl inositol 3' kinase-related kinases. As such, the Rvbs play an integral role in regulating gene expression, cell signaling, cell growth, and the DNA damage response. Their involvement in these processes is conserved from yeast to human and aberrations in Rvb regulation have been linked to a variety of carcinomas. Because Rvbs are essential in a host of cell processes, defining their molecular and biological functions will aid in future research and application. This work provides a structural, functional, and behavioral characterization of Rvb1 and Rvb2 of S .cerevisiae. Rvb1 and Rvb2 together were demonstrated to form a heterohexameric ring complex. Electron microscopy analysis of the endogenous Rvb1/Rvb2 complex showed similar hexameric rings as those observed for the recombinant Rvb1/Rvb2 complex suggesting that this complex is physiologically relevant. The Rvb1/Rvb2 complex exhibited synergistically enhanced ATP-hydrolysis and DNA unwinding activities in comparison to either subunit alone. The Walker B motif involved in ATP-hydrolysis was found to be essential in both subunits for cell viability and for ATPase activity. Synthetic genetic analysis of RVB1 and RVB2 genes with non-essential genes in S. cerevisiae revealed that both RVBs share a high percentage of genetic iii interactions, indicating that they are both involved in the same cellular pathways. In addition, Rvb1 and Rvb2 are highly co-localized in the nucleus during normal cell growth and under various stress conditions suggesting that their function in the cell resides predominantly in the nucleus and may involve the Rvb1/Rvb2 complex. This work will lend general knowledge towards furthering our understanding of these important proteins and provide a foundation for studies of the human Rvbs in cancer therapies.
Lives Worthy of Life and Remembrance: Memorialization of the National Socialist Aktion T4 Euthanasia Programme
Keywords: memorialization
Holocaust
German Studies
euthanasia
Aktion T4
Disability Studies
WWII
monuments
memorials
German suffering

It is estimated that over 70,000 German and Austrian victims deemed mentally and physically disabled by the Nazis lost their lives in the National Socialist euthanasia programmed entitled Aktion T4. These murders prove to be the first instance of mass gassings of a selection of society deemed unwanted, and provided the intellectual and technological framework that was employed in the Extermination Camps. And yet a void in memorialization exists for the topic. Deficient memorialization of such a historically important event in German and Austrian society raises questions as to why this Nazi programme was not memorialized to the same degree as other historical events and victim groups of the Holocaust. The scarce number of representations of the victims in the forms of literature, art, monuments and memorials is indicative of a reluctance or selective remembering of the topic in WWII memorialization practices. The void in memorialization of Aktion T4 is founded in three important and influential factors. Firstly, the negative stigmas associated with mental and physical disabilities, both in confronting the topic, but also presenting it on public display. Secondly, the legal issues in that only a very few number of doctors, caregivers, or commanders of the killing centres were prosecuted and sentenced for their crimes, but rather continued to practice without any repercussions. Finally, the addressing of the topic of German suffering and the representation of German people as victims, and not solely as the perpetrators of WWII. This complex dichotomy of presenting German people as both victims and perpetrators within the same action results in a political nervousness and general avoidance. The topic of Aktion T4 memorialization is pertinent as it speaks not only to the history of the mentally and physically disabled victims, but also to the treatment of people with disabilities today. The memorialization of Aktion T4 and the representation of its victims is an important topic which has been long delegated to the margins of Holocaust memory work. These first victims represent a selected eradication of a group of society deemed unworthy of life, and unworthy of belonging to the German population.
The Incidence, Co-occurrence, and Predictors of Dysphagia, Dysarthria, and Aphasia after Acute Ischemic Stroke
Keywords: stroke
MRI
dysphagia
dysarthria
aphasia

Background- Dysphagia, dysarthria and aphasia are frequent sequelae of stroke. We sought to identify their frequency, co-occurrence, and predictors of them after acute ischemic stroke. Methods- First, we used the Registry of the Canadian Stroke Network’s (RCSN) database (2003–2008) from one stroke centre to identify a random sample of 250 patients with acute ischemic stroke confirmed by magnetic resonance imaging (MRI). We conducted a medical chart review to derive frequency estimates for the presence of dysphagia, dysarthria and aphasia and identified clinical predictors of them from the RCSN database. Second, we conducted a systematic review to identify neuroanatomical predictors of dysphagia after acute ischemic stroke. We searched 14 databases, 17 journals, three conference proceedings and the grey literature using the Cochrance Stroke Group search strategy. We pooled individual level data for the dysphagia outcome, calculating relative risks according to neuroanatomical lesion sites. Finally, from the medical chart review, we evaluated MRI scans for patients with acute lesions within 14 days of stroke onset, deriving clinical and neuroanatomical predictors of the three impairments, using logistic regression. Results – First, incidence estimates for dysphagia, dysarthria, and aphasia were 44% (95% CI, 38-51), 42% (95% CI, 35-48) and 30% (95% CI, 25-37), respectively. The highest clinical predictors were non-alert level of consciousness for dysphagia (OR 2.6, CI 1.03-6.5), symptoms of weakness for dysarthria (OR 5.3, CI 2.4-12.0), and right-sided symptoms for aphasia (OR 7.1, CI 3.1-16.6). Second, for our systematic review, we reviewed 964 abstracts, accepting 84 for full review. Seventeen met our inclusion criteria, providing individual results for 656 patients. Predictors of dysphagia included pontine (RR 3.7, 95% CI 1.5-7.7), medial medullary (RR 6.9, 95% CI 3.4-10.9) and lateral medullary (RR 9.6, 95% CI 5.9-12.8) lesions. Finally, 160 patients met our eligibility criteria for MRI analysis. Strongest predictors included medullary lesions (OR 6.2, 95% CI 1.5 – 25.8) for dysphagia, pontine lesions (OR 7.8, 95% CI 2.7 – 22.9) for dysarthria, and insular lesions (OR 34.4, 95% CI 4.2 – 283.4) for aphasia. Conclusions- We computed the frequency of dysphagia, dysarthria, and aphasia, identifying clinical and whole brain neuroanatomical predictors of their presence.
PDGF-A Signalling Regulates Radially Oriented Movements of Mesoderm Cells During Gastrulation in Xenopus
Keywords: Developmental Biology
Xenopus
Gastrualtion
Cell Migration
Radial Intercalation

The molecular regulation and cellular basis of morphogenesis during Xenopus gastrulation has been a topic of extensive study. In particular, the convergent extension movements that occur in the chordamesoderm are well understood, however less is known about the morphogenesis of other mesoderm regions. Since most of the morphogenetic movements occurring during gastrulation appear to be region autonomous, it is necessary to understand these region specific movements and their contribution to the gastrulation process in order to understand gastrulation as a system. The organization of cells in a region can be indicative of the cell movements that are occurring in that region. Using scanning electron microscopy, I have analyzed the organization of cells in the prechordal mesoderm (PCM) of the gastrula, which is the sub-region of anterior mesoderm that gives rise to the muscles of the ii head. I found that during the middle of gastrulation, PCM cells were oriented with their long axes perpendicular to the overlying blastocoel roof (BCR) and that the orientation of these cells is BCR dependent. By the end of gastrulation, I found that the PCM had thinned from a multi-layered tissue to single layer of cells in contact with the BCR, suggesting radial interaction of the PCM. Furthermore, cells in corresponding regions on the lateral and ventral sides of the embryo were found to be oriented similarly, suggesting that radially directed movements could be common throughout the anterior mesoderm. Three isoforms of the Platelet Derived Growth Factor A (PDGF-A) are expressed in the BCR and its cognate receptor, PDGFRα, is expressed in the PCM. I have shown that two isoforms of the PDGF-A isoforms (lf-PDGF-A and int-PDGF-A) remain associated with the surface of secreting cells and thus signal over a short range, while a third (sf-PDGF-A) is diffusible and can signal over long distances. My work has shown that radial intercalation of the PCM is instructively regulated by a concentration gradient of sf-PDGF-A, which forms in the mesoderm over a distance of approximately 200 μm by the diffusion of molecules through intercellular gaps. My work describes for the first time, the molecular regulation of radial intercalation.
Mitochondrial-localized Phosphatidylethanolamine in Mitochondrial Dynamics and Autophagy
Keywords: Mitochondria
phosphatidylethanolamine
lipids
mitochondrial fusion
mitochondrial dynamics
autophagy
phosphatidylserine decarboxylase

Phosphatidylethanolamine (PE) constitutes a significant proportion of total phospholipids in biological membranes. A major route of PE biosynthesis occurs via the decarboxylation of phosphatidylserine (PS) by the inner-mitochondrial-membrane (IMM)-localized PS decarboxylase (PSD). The only other known phospholipids that are synthesized in mitochondria are the mitochondrial-enriched phosphatidylglycerol (PG) and cardiolipin (CL); the synthesis of other biological lipids occurs mostly in the endoplasmic reticulum (ER). Hence, the mitochondrial-localization of PSD led me to speculate that PE within the mitochondrial membrane might have important functions. In this thesis, I describe my findings that mitochondrial-localized PE plays an important role in mitochondrial membrane remodelling and autophagy, a conserved quality control mechanism. Mitochondrial PE promotes mitochondrial membrane fusion by enhancing the biogenesis of the short isoform of mitochondrial genome maintenance 1 (s-Mgm1), a key mitochondrial fusion protein. The biophysical properties of PE on the mitochondrial membrane also promote fusion likely by increasing the rate of lipid mixing during fusion. In addition, mitochondrial PE is important for oxidative phosphorylation and the maintenance of mitochondrial ATP levels, crucial mitochondrial homeostatic functions. I also demonstrate that a reduction in mitochondrial PE impairs autophagy likely by impeding autophagosome formation, expansion and/or fusion with the vacuole in yeast. My results provide additional insight into the functional importance of mitochondrial PE and highlight the specific lipid composition of the mitochondrial membrane as a key player in mitochondrial membrane fusion and autophagy.
For us, by us: political geographies of race, sexuality and health in the work of ethno-specific AIDS service organizations in global-multicultural Toronto
Keywords: AIDS
social services
race
geography
queer
sexual health

This dissertation traces the role of racialization in the production of spaces of sexual health organizing and social service provision. Drawing on insights from geographies of sexualities and the literatures on critical race theory, it examines how spaces of care that emerged from local responses to HIV/AIDS in 1980s Toronto (e.g., AIDS service organizations or ASOs) became sites for the normalization of whiteness and the exclusion of people of colour. It also documents the ways that activists of colour disidentify with mainstream ASOs by naming the exclusions – and deadly effects – engendered by white normalization and by adopting “for us, by us” approaches to sexual health that symbolically and literally made specific spaces for people of colour. Central to these acts of disidentification, I argue, are geographical discourses and practices, which include place-making tactics that mark certain spaces as “ethno-specific” and the identification and targeting of particular sites (e.g., event-spaces, clubs, neighbourhoods) for sexual health outreach to communities of colour. This dissertation is based on case studies of three ethno-specific ASOs in Toronto: the Black Coalition for AIDS Prevention, the Asian Community AIDS Services, and the Alliance for South Asian AIDS Prevention. Interviews with current and former workers (board members, volunteers and paid staff) form the main archive – along with supplementary archival and media analysis and participant observations – for the analysis that follows. A consideration of the geographies of e-ASOs’ work highlights the political salience of race for sexual and health politics, and provides a forum for bringing geographies of sexualities into conversation with queer of colour analysis. It thus contributes to the theoretical and political project of anti-racist geographies of sexualities not only by naming the exclusions that people of colour face in sexual political spaces, but also by focusing on their tactics of survival, resilience and resistance.
Characterization of Epstein-Barr Nuclear Antigen 1 (EBNA1) Effects on Host Cells and its Functional Interaction with the Cellular Kinase CK2
Keywords: Epstein Barr Virus
Protein Kinase CK2

Epstein-Barr virus (EBV) immortalizes host cells as part of its latent mode of infection, and the Epstein-Barr Nuclear Antigen 1 (EBNA1) is essential for establishing EBV latency. In addition to its roles on the EBV genome, increasing evidence suggests that EBNA1 contributes to cell immortalization and survival. The aim of this thesis is to further characterize the effects of EBNA1 on cells. Firstly, I performed a 2D-DiGE proteomic screen on the nuclear proteome of nasopharyngeal carcinoma (NPC) cells with or without EBNA1 expression, and identified several new proteins whose levels were modulated by EBNA1. In addition, I found that stable EBNA1 expression resulted in an accumulation of ROS (reactive oxygen species) in NPC cells, which may be partly due to an EBNA1-induced increase in the transcript and protein levels of NOX1 and NOX2 NADPH oxidases. These findings indicate new ways that EBNA1 can alter the host cell environment and contribute to the development of NPC. EBNA1 exerts multiple effects through interactions with cellular proteins. Here, I also investigated the EBNA1 interaction with the cellular kinase CK2 (Casein Kinase 2), and showed that this interaction is critical for the ability of EBNA1 to disrupt PML (promyelocytic leukemia) nuclear bodies, that mediate tumour suppressor functions and the anti-viral response. Specifically, EBNA1 increases the association of two cellular enzymes, CK2 and USP7 (ubiquitin specific protease 7), with PML nuclear bodies, which leads to the phosphorylation and polyubiqutylation of the PML proteins resulting in their degradation. Lastly, through the characterization of the EBNA1-CK2 interaction, I discovered a novel protein binding pocket in CK2β, containing a KSSR motif, which mediates protein-protein interactions with viral and cellular proteins. The CK2β KSSR motif has the propensity to bind polyserine tracts on EBNA1 as well as on another cellular protein, ARKL1.
Optical Spectroscopy of Two-dimensional Electronic Materials
Keywords: Mott insulator
optical spectroscopy
Raman
superconductor

This thesis presents optical studies of several low-dimensional electronic materials. Reflectance, transmittance, ellipsometry and Raman scattering were employed to measure the fundamental excitations of the materials under study. The electrodynamics of BSCCO two-dimensional atomic crystals were investigated as a function of thickness. The thickness dependence of the optical response indicates a tendency of the BSCCO surface to become insulating. Furthermore, the characteristic energy scale of magnetic fluctuations was observed to increase in the atomic crystals. A series of superconducting Cu
Image-guided Predictions of Liposome Transport in Solid Tumours
Keywords: Drug Delivery
Imaging
Liposomes
Transport

Due to the ability to preferentially accumulate and deliver drug payloads to solid tumours, liposomes have emerged as an exciting therapeutic strategy for cancer therapy. Unfortunately, the initial excitement was dampened by limited clinical results, where only negligible increases in patient survival following liposome therapy have been observed. What are the reasons for the limited clinical efficacy? Is the nanoparticle formulation optimal? Is the enhanced permeability and retention effect overstated? What are the barriers limiting the delivery of drugs to cancer cells? What is the optimal dosing and treatment schedule? Addressing these questions requires developing quantitative tools to understand the behaviour of liposomes in vivo, such as pharmacokinetics, biodistribution, intra-tumoural accumulation, and drug release. Central to each of these questions is the concept of transport - the collection of biophysical processes responsible for the delivery of molecules to tissues. Understanding transport means understanding the crucial links between the spatio-temporal accumulation of liposomes, the physicochemical properties of liposomes, and properties of the tumour microenvironment. In this thesis, a biophysical mathematical transport model is developed that when used in combination with non-invasive imaging methods can predict liposome transport in solid tumours. The mathematical transport framework is validated in its ability to predict the bulk and intra-tumoural accumulation of liposomes based on biophysical transport properties of solid tumours. Furthermore, novel imaging methods are developed and used to elucidate the crucial links between transport barriers and spatial heterogeneity in liposome accumulation. Finally, methods are presented to integrate quantitative imaging and mathematical modelling such that an accurate prediction of liposome transport in solid tumours is possible. In summary, this thesis presents and validates an image-guided mathematical framework that can be used to guide the rational application of liposomes for the treatment of solid tumours.
Mantle Dynamics Following Supercontinent Formation
Keywords: Continental insulation
Mantle convection
Mantle plume
Pangea
Subduction zones
Supercontinent

This thesis presents mantle convection numerical simulations of supercontinent formation. Approximately 300 million years ago, through the large-scale subduction of oceanic sea floor, continental material amalgamated to form the supercontinent Pangea. For 100 million years after its formation, Pangea remained relatively stationary, and subduction of oceanic material featured on its margins. The present-day location of the continents is due to the rifting apart of Pangea, with supercontinent dispersal being characterized by increased volcanic activity linked to the generation of deep mantle plumes. The work presented here investigates the thermal evolution of mantle dynamics (e.g., mantle temperatures and sub-continental plumes) following the formation of a supercontinent. Specifically, continental insulation and continental margin subduction are analyzed. Continental material, as compared to oceanic material, inhibits heat flow from the mantle. Previous numerical simulations have shown that the formation of a stationary supercontinent would elevate sub-continental mantle temperatures due to the effect of continental insulation, leading to the break-up of the continent. By modelling a vigorously convecting mantle that features thermally and mechanically distinct continental and oceanic plates, this study shows the effect of continental insulation on the mantle to be minimal. However, the formation of a supercontinent results in sub-continental plume formation due to the re-positioning of subduction zones to the margins of the continent. Accordingly, it is demonstrated that continental insulation is not a significant factor in producing sub-supercontinent plumes but that subduction patterns control the location and timing of upwelling formation. A theme throughout the thesis is an inquiry into why geodynamic studies would produce different results. Mantle viscosity, Rayleigh number, continental size, continental insulation, and oceanic plate boundary evolution are explored in over 600 2D and over 20 3D numerical simulations to better understand how modelling method affects conclusions on mantle convection studies. The results from this thesis show that the failure to model tectonic plates, a high vigour of convection, and a (pseudo) temperature-dependent viscosity would distort the role of mantle plumes, continent insulation, and subduction in the thermal evolution of mantle dynamics.