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Folate is an important regulator of hippocampal neurogenesis, and folic acid is needed prenatally to reduce the risk of neural tube defects in utero. Both high levels of folic acid and low levels of folate can be harmful to health, as low levels of folate have been linked to several diseases while high folic acid supplements can mask a vitamin B12 deficiency. Depressed patients exhibit folate deficiencies, lower levels of hippocampal neurogenesis, elevated levels of homocysteine, and elevated levels of the stress hormone, cortisol, which may be inter-related. Here, we are interested in whether different doses of natural folate or synthetic folic acid diets can influence neurogenesis in the hippocampus, levels of plasma homocysteine, and serum corticosterone in adult female rats. Adult female Sprague-Dawley rats underwent dietary interventions for 29 days. Animals were randomly assigned to six different dietary groups: folate deficient + succinylsulfathiazole (SST), low 5-methyltetrahydrofolate (5-MTHF), low 5-MTHF + (SST), high 5-MTHF + SST, low folic acid, and high folic acid. SST was added to a subset of the 5 MTHF diets to eliminate folic acid production in the gut. Before and after dietary treatment, blood samples were collected for corticosterone and homocysteine analysis, and brain tissue was collected for neurogenesis analysis. High folic acid and low 5-MTHF without SST increased the number of immature neurons (doublecortin-expressing cells) within the ventral hippocampus compared to folate deficient controls. Low 5-MTHF without SST significantly increased the number of immature neurons compared to low and high 5-MTHF + SST, indicating that SST interfered with elevations in neurogenesis. Low folic acid and high 5-MTHF+SST reduced plasma homocysteine levels compared to controls, but there was no significant effect of diet on serum corticosterone levels. Low folic acid and high 5-MTHF+SST reduced the number of mature new neurons in the ventral hippocampus (BrdU/NeuN-positive cells) compared to folate deficient controls. Overall folic acid dose-dependently influenced neurogenesis with low levels decreasing but high levels increasing neurogenesis in the ventral hippocampus, suggesting this region, which is important for regulating stress, is particularly sensitive to folic acid in diets. Furthermore, the addition of SST negated the effects of 5-MTHF to increase neurogenesis in the ventral hippocampus.
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The full abstract for this thesis is available in the body of the thesis, and will be available when the embargo expires.
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The full abstract for this thesis is available in the body of the thesis, and will be available when the embargo expires.
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What does the ideal housing type look like? A 2015 online survey of individuals living in the Loire-Atlantique Département in France provided 1,134 interviews, which we analyze using a mixed-effect probit model. We look at the probability of living in the ideal housing type related to 28 variables of dwelling and respondent characteristics, density perception, district perception, type of municipality, and proximity to education, healthcare and food facilities. The issue is important because certain housing types yield greater land consumption and longer trips. Local governments support infill developments with higher built-up density levels to conserve land and support walking, cycling, and transit. We find that the probability of living in the ideal housing type has no relationship to density perception. What matters is a positive district perception and proximity to healthcare. Well-designed infill development with higher built-up density levels can succeed, associating a higher probability of living in the ideal housing type with suitable urban forms given the physical constraints of territories, in a sustainable development framework.
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This study evaluates linear programming (LP) and positive mathematical programming (PMP) approaches for 3,400 farm-level models implemented in the SWISSland agent-based agricultural sector model. To overcome limitations of PMP regarding the modelling of investment decisions, we further investigated whether the forecasting performance of farm-level models could be improved by applying LP to animal production activities only, where investment in new sectors plays a major role, while applying PMP to crop production activities. The database used is the Swiss Farm Accountancy Data Network. Ex-post evaluation was performed for the period from 2005 to 2012, with the 2003-2005 three-year average as a base year. We found that PMP applied to crop production activities improves the forecasting performance of farm-level models compared to LP. Combining PMP for crop production activi-ties with LP for modelling investment decisions in new livestock sectors improves the forecasting performance compared to PMP for both crop and animal production activities, especially in the medium and long term. For short-term forecasts, PMP for all production activities and PMP combined with LP for animal production activities produce similar results.
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