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- Tabiri, S, et al.
(författare)
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- 2021
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swepub:Mat__t
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- Bravo, L, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 9. |
- Costello, David M., et al.
(författare)
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Global patterns and controls of nutrient immobilization on decomposing cellulose in riverine ecosystems
- 2022
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Ingår i: Global Biogeochemical Cycles. - : John Wiley & Sons. - 0886-6236 .- 1944-9224. ; 36:3
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Tidskriftsartikel (refereegranskat)abstract
- Microbes play a critical role in plant litter decomposition and influence the fate of carbon in rivers and riparian zones. When decomposing low-nutrient plant litter, microbes acquire nitrogen (N) and phosphorus (P) from the environment (i.e., nutrient immobilization), and this process is potentially sensitive to nutrient loading and changing climate. Nonetheless, environmental controls on immobilization are poorly understood because rates are also influenced by plant litter chemistry, which is coupled to the same environmental factors. Here we used a standardized, low-nutrient organic matter substrate (cotton strips) to quantify nutrient immobilization at 100 paired stream and riparian sites representing 11 biomes worldwide. Immobilization rates varied by three orders of magnitude, were greater in rivers than riparian zones, and were strongly correlated to decomposition rates. In rivers, P immobilization rates were controlled by surface water phosphate concentrations, but N immobilization rates were not related to inorganic N. The N:P of immobilized nutrients was tightly constrained to a molar ratio of 10:1 despite wide variation in surface water N:P. Immobilization rates were temperature-dependent in riparian zones but not related to temperature in rivers. However, in rivers nutrient supply ultimately controlled whether microbes could achieve the maximum expected decomposition rate at a given temperature. Collectively, we demonstrated that exogenous nutrient supply and immobilization are critical control points for decomposition of organic matter.
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| 10. |
- D'Ascenzi, F., et al.
(författare)
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Left atrial remodeling in patients undergoing transcatheter aortic valve implantation : a speckle tracking prospective study
- 2013
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Ingår i: European Heart Journal. - : Oxford University Press. - 0195-668X .- 1522-9645. ; 34:Supplement: 1, s. 338-338
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Background: Aortic Stenosis (AS) results in several Left Ventricular (LV) disturbances as well as progressive Left Atrial (LA) enlargement and dysfunction. Transcatheter Aortic Valve Implantation (TAVI) reverses LV remodelling and improves overall systolic function but its effect on LA function remains undetermined. The aim of this prospective study was toinvestigate the effects of TAVI on LA structure and function.Material and methods: We studied thirty-two patients with severe symptomatic AS and high surgical risk who underwent TAVI, using standard and 2-dimensional speckle-tracking echocardiography before, at 40-day and at 3-month follow-up.Results: Following TAVI, mean transvalvular gradient reduced (p<0.001). Both LA mean area index and LA mean volume index decreased at 40-day (16.2±6.4 vs. 12.5±2.9 cm2/m2, and 47.3±12.0 vs. 42.8±12.5 mL/m2, respectively, p<0.05) and values remained unchanged at 3 months. The reduction of LA size was accompanied by a significant increase in global PALS (14.4±3.9% vs. 19.1±4.7%, p<0.001) and global PACS (8.4±2.5% vs. 11.0±4.1%, p<0.05) at 3-month. After the procedure, LA stiffness measurements decreased and became significant at 3-month follow up (p<0.001). Pre-procedural trans-aortic mean gradient and pre-procedural LA volume were identified as predictors of global PALSincrease (p<0.0001) while the delta drop in trans-aortic mean gradient as predictors of LA volume index reduction 3 months after TAVI (p<0.0001).Conclusion: TAVI is associated with significant recovery of LA structure and function suggesting a reverse cavity remodelling. Such functional recovery is determined by the severity of pre-procedural valve stenosis.
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