208 research outputs found
Sources, Distributions, and Dynamics of Dissolved Organic Matter in the Canada and Makarov Basins
A comprehensive survey of dissolved organic carbon (DOC) and chromophoric dissolved organic matter (CDOM) was conducted in the Canada and Makarov Basins and adjacent seas during 2010â2012 to investigate the dynamics of dissolved organic matter (DOM) in the Arctic Ocean. Sources and distributions of DOM in polar surface waters were very heterogeneous and closely linked to hydrological conditions. Canada Basin surface waters had relatively low DOC concentrations (69 ± 6 ÎŒmol Lâ1), CDOM absorption (a325: 0.32 ± 0.07 mâ1) and CDOM-derived lignin phenols (3 ± 0.4 nmol Lâ1), and high spectral slope values (S275â295: 31.7 ± 2.3 ÎŒmâ1), indicating minor terrigenous inputs and evidence of photochemical alteration in the Beaufort Gyre. By contrast, surface waters of the Makarov Basin had elevated DOC (108 ± 9 ÎŒmol Lâ1) and lignin phenol concentrations (15 ± 3 nmol Lâ1), high a325 values (1.36 ± 0.18 mâ1), and low S275â295 values (22.8 ± 0.8 ÎŒmâ1), indicating pronounced Siberian river inputs associated with the Transpolar Drift and minor photochemical alteration. Observations near the Mendeleev Plain suggested limited interactions of the Transpolar Drift with Canada Basin waters, a scenario favoring export of Arctic DOM to the North Atlantic. The influence of sea-ice melt on DOM was region-dependent, resulting in an increase (Beaufort Sea), a decrease (Bering-Chukchi Seas), and negligible change (deep basins) in surface DOC concentrations and a325 values. Halocline structures differed between basins, but the Canada Basin upper halocline and Makarov Basin halocline were comparable in their average DOC (65â70 ÎŒmol Lâ1) and lignin phenol concentrations (3â4 nmol Lâ1) and S275â295 values (22.9â23.7 ÎŒmâ1). Deep-water DOC concentrations decreased by 6â8 ÎŒmol Lâ1 with increasing depth, water mass age, nutrient concentrations, and apparent oxygen utilization. Maximal estimates of DOC degradation rates (0.036â0.039 ÎŒmol Lâ1 yrâ1) in the deep Arctic were lower than those in other ocean basins, possibly due to low water temperatures. DOC concentrations in bottom waters (\u3e2500 m; 46 ± 2 ÎŒmol Lâ1) of the Canada and Makarov Basins were slightly lower than those reported for deep waters of the Eurasian Basin and Nordic Seas. Elevated a325 values (by 10â20%) were observed near the seafloor, indicating biological activity in Arctic basin sediments
Le Forum, Vol. 44 #2
https://digitalcommons.library.umaine.edu/francoamericain_forum/1104/thumbnail.jp
Le Forum, Vol. 41 No. 3
https://digitalcommons.library.umaine.edu/francoamericain_forum/1092/thumbnail.jp
Aortic insufficiency following transcatheter aortic valve replacement is underestimated by echocardiography compared with cardiac MRI
Le Forum, Vol. 42 No. 4
https://digitalcommons.library.umaine.edu/francoamericain_forum/1097/thumbnail.jp
Being Barefoot. Prevalence at Home, in School and during Sport: A Cross-Sectional Survey of 714 New Zealand Secondary School Boys
Background: It may be assumed that a combination of culture, climate and economic resource are the major reasons that non-industrialised countries have a higher prevalence of barefoot activity. New Zealand is an industrialised country with comparable resources to that of many European countries; however, it seems to remain socially acceptable to carry out barefoot activities. A chance observation of students competing barefoot on a tartan track, prompted us to determine the prevalence of barefoot activity in an all-boys secondary school in Auckland New Zealand. Method: An 11-question survey was administered at an Auckland boys secondary school, of high socioeconomic status, to determine the footwear habits of students (n=714) during: a) daily life b) school life (c) physical education class and (d) sport. To classify students as habitually barefoot or shod, students were asked to select whether they were barefoot most of the time (2-points), half of the time (1-point) or none of the time (0-points) in three settings: around the house, during sport and during school. A score of â„3 was required to be considered habitually barefoot. Participants were also asked to specify, when running at their most recent athletics event (100m â 3,000m) on a track, whether they ran barefoot, in shoes, in spikes or another type of footwear. Finally, participants were asked to indicate if leg pain had interrupted running during the previous 12-months. Analysis was conducted using IBM SPSS. Results: 45% (95% CI: 41.5% - 49.5%) of the participants in our sample were classified as habitually barefoot. More than half of the sample reported being barefoot most of the time at home (n=404, 56.6%) and during PE class (n=420, 58.8%). Over 50% of the sample reported being barefoot half of the time or more during sport (n=380, 53.2%). A smaller amount went to the supermarket (n=140, 19.6%) or took the bus (n=59, 8.3%) whilst barefoot around half of the time or more. The percentage of barefoot competitors declined with increasing distance: 100m (46.5%), 200m (41.8%), 400m (38%), 800m (31%), 1500m (31%) and 3,000m (20%). The prevalence of leg pain interfering with running was 23.5%. There was no difference in the prevalence of leg pain between those classified as habitually barefoot and shod (Χ2(1, N=603) = 0.005, p = 0.946). Conclusion: The results of this survey demonstrate that over 50% of students at an all-boys secondary school in Auckland, of high socioeconomic status, are barefoot at home, during physical education and sport half of the time or more. These results may point towards a cultural difference between New Zealand and other modern industrialised countries
Le FORUM, Vol. 35 No. 3
https://digitalcommons.library.umaine.edu/francoamericain_forum/1031/thumbnail.jp
Aortic insufficiency following transcatheter aortic valve replacement is underestimated by echocardiography compared with cardiac MRI
Failure to repair endogenous DNA damage in ÎČ-cells causes adult-onset diabetes in mice
Age is the greatest risk factor for the development of type 2 diabetes mellitus (T2DM). Age-related decline in organ function is attributed to the accumulation of stochastic damage, including damage to the nuclear genome. Islets of T2DM patients display increased levels of DNA damage. However, whether this is a cause or consequence of the disease has not been elucidated. Here, we asked if spontaneous, endogenous DNA damage in ÎČ-cells can drive ÎČ-cell dysfunction and diabetes, via deletion of Ercc1, a key DNA repair gene, in ÎČ-cells. Mice harboring Ercc1-deficient ÎČ-cells developed adult-onset diabetes as demonstrated by increased random and fasted blood glucose levels, impaired glucose tolerance, and reduced insulin secretion. The inability to repair endogenous DNA damage led to an increase in oxidative DNA damage and apoptosis in ÎČ-cells and a significant loss of ÎČ-cell mass. Using electron microscopy, we identified ÎČ-cells in clear distress that showed an increased cell size, enlarged nuclear size, reduced number of mature insulin granules, and decreased number of mitochondria. Some ÎČ-cells were more affected than others consistent with the stochastic nature of spontaneous DNA damage. Ercc1-deficiency in ÎČ-cells also resulted in loss of ÎČ-cell function as glucose-stimulated insulin secretion and mitochondrial function were impaired in islets isolated from mice harboring Ercc1-deficient ÎČ-cells. These data reveal that unrepaired endogenous DNA damage is sufficient to drive ÎČ-cell dysfunction and provide a mechanism by which age increases the risk of T2DM. </p
- âŠ