During the nineteenth and the twentieth centuries, the world has moved from a manufacturing to service-based economy, where the twentieth first century, will be the” century of services”, and will transform into the century of “international services” (Clark and Rajaratnam, 1999).

Stress is an important risk factor for the development of clinical depression, yet little is known about the neurobiological mechanisms by which stress might promote depressive symptomatology. The brain is particularly susceptible to the negative effects of stress, as high levels of stress hormones result in decreased hippocampal neurogenesis, slowed cell maturation, and decreased cell complexity. Although we already know that these neurobiological changes are associated with significant impairments in important psychological functions such as learning, memory and motivation, we know little about the molecular details of this stress-induced remodeling and how it contributes to the development of depression. Currently, one candidate molecule of particular interest is reelin, an extracellular matrix protein responsible for regulating neuronal maturation and synaptic plasticity in the adult brain. Interestingly, recent post- mortem analyses indicate that reelin expression is decreased in depressed patients. Similarly, preclinical research has shown that repeated glucocorticoid administration significantly reduces reelin expression in the adult hippocampus. Combined, these results suggest that reelin may be an important protein to examine in regards to the pathogenesis of depression as well as a potential therapeutic target for the treatment of this disorder. The goal of this dissertation is to provide a comprehensive examination of the influence repeated glucocorticoid administration has on reelin expression in the rat hippocampus, and how this relates to the pathogenesis of depression. In chapter 2 we examined how co-treatment with the stress hormone corticosterone (CORT), and the antidepressant imipramine, influence reelin expression in the proliferative region of the hippocampus. In addition we determined whether changes in reelin expression are associated with alterations in neurogenesis and behavioral measures of depression. Results revealed that imipramine prevents CORT-induced downregulation of reelin in the hippocampus, and that these changes parallel improvements in FST behavior, increased neurogenesis and enhanced maturation of immature granule cells. Importantly, these data provide further evidence of reelin’s role in depression and establish this protein as a target of antidepressant treatment. In chapter 3 we examined the effect of CORT on a number of interneuron markers that co-localize with reelin throughout the hippocampus to determine whether the populations of neurons that express reelin are lost or are no longer expressing this protein. Results of this study indicate that CORT influences a number of interneuron markers in a region-specific manner in the hippocampus, but does not cause these cell populations to die, suggesting that CORT exploits an intracellular mechanism to regulate reelin expression in the hippocampus. Finally, in chapter 4, the influence of CORT on MeCP2 and DNMT1, two markers associated with DNA methylation, was examined in the hippocampus to elucidate a potential intracellular mechanism for CORT-induced reelin deficits. Results of this study indicate that CORT has no influence on global protein levels of these markers, but significantly increases the number of MeCP2-expressing cells in the proliferative subgranular zone of the hippocampus, suggesting that there is an increase in the number of methylated cells in this region. While it cannot be conclude from this study that increased methylation causes reelin deficits, the fact that an increase in MeCP2 is seen in the exact region where reelin deficits are most pronounced suggest it is possible. Moreover, these findings are novel, and suggest a role for MeCP2, and more generally, DNA methylation, in the neurobiology of depression. Collectively, the results of this dissertation enhance our understanding of the functional consequences of altered hippocampal neuroplasticity on the development of depressive symptomatology, and the role that reelin may play in this process. They also provide further support for reelin as a novel therapeutic target for the treatment of major depression.

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X-ray and neutron computed tomography (CT) have been used successfully for the non-destructive imaging of artifact in art conservation. These applications range from object investigations to the use of micro-focus CT for experimental studies. While there is precedent for the use of CT in art conservation, the method is still limited in application partially due to restricted access to facilities and the high cost of producing publishable results. The purpose of this study was to identify alternative CT methods including the use of different radiation sources and industrial imaging system. Both investigations of the use of low-flux neutron CT at the Royal Military College in Kingston compared to high-flux neutron CT at the Advanced Neutron Tomography And Radiography Experimental System (ANTARES) at FRM-II in Garching, Munich and the use of megavoltage gamma ray computed tomography at Kingston General Hospital in Kingston successfully imaged the corroded metal artifacts. The artifacts investigated were from the Diniacopoulos Collection at Queen’s University and were underwater concretions of L’Anse aux Bouleaux provided by Parks Canada. This study also evaluated the Xradia XCT-400 for comparison to similar systems used in conservation. This evaluation also provided successful images of corroded metal coins from the Diniacopoulos Collection for use in identification. To address the issue of cost prohibitive image analysis programs, a workflow using the open-source software programs ImageVis3D, 3DSlicer and ImageJ was developed. This workflow would enable researchers and conservators to produce publishable images and analyze the information in the CT data sets. Additionally, this workflow addresses some common research questions that might arise during investigations that would guide conservators in optimizing their imaging parameters and image analysis. The combination of the alternative radiation sources and the open-source workflow allows for greater accessibility of CT for conservators and researchers. While the preliminary success of the study is promising, more research is needed to optimize the scanning parameters and image analysis through the use of phantoms and comparisons to traditional investigative methods in conservation. / Thesis (Master, Art Conservation) -- Queen's University, 2011-09-09 14:25:25.219

<p><font face="Arial"> <p align="left">In this study, the capabilities of Neutron Radiography (NRad) and -Tomography (NTomo), as well as X-ray Radiography (XRad) to investigate chlorides and chlorides corrosion effects within steel reinforced laboratory concrete samples are practically explored. Capabilities of Scanning Electron Microscopy (SEM), Prompt Gamma Neutron Activation Analysis (PGNAA), Particle Induced X-ray Emission (PIXE), Small-Angle Neutron Scattering (SANS), Neutron Diffraction (NDIFF) and X-ray Diffraction (XDIFF) analytical techniques are also explored through review of literature.</p> </font></p>

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