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Introduction: Obstructive sleep apnea (OSA) is increasingly recognized as a risk factor for cognitive decline, and has been associated with structural brain alterations in regions relevant to memory processes and Alzheimer’s disease. However, it is unclear whether OSA is associated with disrupted functional connectivity (FC) patterns between these regions in late middle-aged and older populations. Thus, we characterized the associations between OSA severity and resting-state FC between the default mode network (DMN) and medial temporal lobe (MTL) regions. Second, we explored whether significant FC changes differed depending on cognitive status and were associated with cognitive performance. Methods: Ninety-four participants [24 women, 65.7 ± 6.9 years old, 41% with Mild Cognitive Impairment (MCI)] underwent a polysomnography, a comprehensive neuropsychological assessment and a resting-state functional magnetic resonance imaging (MRI). General linear models were conducted between OSA severity markers (i.e., the apnea-hypopnea, oxygen desaturation and microarousal indices) and FC values between DMN and MTL regions using CONN toolbox. Partial correlations were then performed between OSA-related FC patterns and (i) OSA severity markers in subgroups stratified by cognitive status (i.e., cognitively unimpaired versus MCI) and (ii) cognitive scores in the whole sample. All analyzes were controlled for age, sex and education, and considered significant at a p < 0.05 threshold corrected for false discovery rate. Results: In the whole sample, a higher apnea-hypopnea index was significantly associated with lower FC between (i) the medial prefrontal cortex and bilateral hippocampi, and (ii) the left hippocampus and both the posterior cingulate cortex and precuneus. FC patterns were not associated with the oxygen desaturation index, or micro-arousal index. When stratifying the sample according to cognitive status, all associations remained significant in cognitively unimpaired i

In the Canadian Forces (CF), injuries involving impact of the head within an enclosed space (a vehicle) are common and the possibility of cortical impact injuries in such cases is quite high. While conventional neuroimaging techniques may show normal results, cognitive problems are frequently reported by people who have sustained cortical impact or traumatic brain injury. In order to develop a comprehensive clinical diagnosis for return soldiers that might experience signs and symptoms of possible brain injury due to cortical impact, the present study aimed to compare motor vehicle accident (MVA) victims where cortical impact is prevalent to an age matched control group. All MVA victims were investigated using carefully selected neuroimaging and electrophysiological procedures together with a validated neurocognitive test battery.

info:eu-repo/semantics/published, Conference Paper

info:eu-repo/semantics/published, Conference Paper

Laboratory experiments using equilibrium partitioning in closed systems and modelling studies were carried out to investigate the possibility of As release from tailings at the McClean Lake operation in the Athabasca Basin of northern Saskatchewan. Untreated acid raffinate solutions associated with U mill tailings contain up to 700 mg/l dissolved As. To reduce the concentration of As and other contaminants in acid tailing slurries, ferric sulphate may be added to the acid raffinates to ensure that the molar Fe/As ratio is at least 3. Tailings slurries are then neutralised with lime to pH 4, and subsequently to pH 7-8. Most of the As is associated with the secondary arsenate minerals, scorodite and annabergite. However, a few percent is adsorbed and/or co-precipitated, mainly by ferrihydrite. The results of the experiments and modelling show that the amount of As that could be readily released to pore waters is about 0.2% of the total As in the tailings and that such releases may contribute no more than a few mg/l of dissolved As to tailings pore waters in the long term., Laboratory experiments using equilibrium partitioning in closed systems and modelling studies were carried out to investigate the possibility of As release from tailings at the McClean Lake operation in the Athabasca Basin of northern Saskatchewan. Untreated acid raffinate solutions associated with U mill tailings contain up to 700 mg/l dissolved As. To reduce the concentration of As and other contaminants in acid tailing slurries, ferric sulphate may be added to the acid raffinates to ensure that the molar Fe/As ratio is at least 3. Tailings slurries are then neutralised with lime to pH 4, and subsequently to pH 7-8. Most of the As is associated with the secondary arsenate minerals, scorodite and annabergite. However, a few percent is adsorbed and/or co-precipitated, mainly by ferrihydrite. The results of the experiments and modelling show that the amount of As that could be readily released to pore waters is about 0.2% of the total As in the tailings and that such releases may contribute no more than a few mg/l of dissolved As to tailings pore waters in the long term.