| 1. |
- Haeni, M., et al.
(författare)
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Winter respiratory C losses provide explanatory power for net ecosystem productivity
- 2017
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Ingår i: Journal of Geophysical Research - Biogeosciences. - 2169-8953. ; 122:1, s. 243-260
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Tidskriftsartikel (refereegranskat)abstract
- Accurate predictions of net ecosystem productivity (NEPc) of forest ecosystems are essential for climate change decisions and requirements in the context of national forest growth and greenhouse gas inventories. However, drivers and underlying mechanisms determining NEPc (e.g., climate and nutrients) are not entirely understood yet, particularly when considering the influence of past periods. Here we explored the explanatory power of the compensation day (cDOY)-defined as the day of year when winter net carbon losses are compensated by spring assimilation-for NEPc in 26 forests in Europe, North America, and Australia, using different NEPc integration methods. We found cDOY to be a particularly powerful predictor for NEPc of temperate evergreen needleleaf forests (R2=0.58) and deciduous broadleaf forests (R2=0.68). In general, the latest cDOY correlated with the lowest NEPc. The explanatory power of cDOY depended on the integration method for NEPc, forest type, and whether the site had a distinct winter net respiratory carbon loss or not. The integration methods starting in autumn led to better predictions of NEPc from cDOY then the classical calendar method starting 1 January. Limited explanatory power of cDOY for NEPc was found for warmer sites with no distinct winter respiratory loss period. Our findings highlight the importance of the influence of winter processes and the delayed responses of previous seasons' climatic conditions on current year's NEPc. Such carry-over effects may contain information from climatic conditions, carbon storage levels, and hydraulic traits of several years back in time.
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| 2. |
- Gal, R. Le, et al.
(författare)
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The ortho-to-para ratio of H2Cl+: Quasi-classical trajectory calculations and new simulations in light of new observations
- 2017
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 608, s. A96-
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Tidskriftsartikel (refereegranskat)abstract
- Multi-hydrogenated species with proper symmetry properties can present different spin configurations, and thus exist under different spin symmetry forms, labeled as para and ortho for two-hydrogen molecules. We investigated here the ortho-to-para ratio (OPR) of H2Cl+ in the light of new observations performed in the z = 0.89 absorber toward the lensed quasar PKS 1830−211 with the Atacama Large Millimeter/submillimeter Array (ALMA). Two independent lines of sight were observed, to the southwest (SW) and northeast (NE) images of the quasar, with OPR values found to be 3.15 ± 0.13 and 3.1 ± 0.5 in each region, respectively, in agreement with a spin statistical weight of 3:1. An OPR of 3:1 for a molecule containing two identical hydrogen nuclei can refer to either a statistical result or a high-temperature limit depending on the reaction mechanism leading to its formation. It is thus crucial to identify rigorously how OPRs are produced in order to constrain the information that these probes can provide. To understand the production of the H2Cl+ OPR, we undertook a careful theoretical study of the reaction mechanisms involved with the aid of quasi-classical trajectory calculations on a new global potential energy surface fit to a large number of high-level ab initio data. Our study shows that the major formation reaction for H2Cl+ produces this ion via a hydrogen abstraction rather than a scrambling mechanism. Such a mechanism leads to a 3:1 OPR, which is not changed by destruction and possible thermalization reactions for H2Cl+ and is thus likely to be the cause of observed 3:1 OPR ratios, contrary to the normal assumption of scrambling.
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| 4. |
- Moraghebi, Roksana, et al.
(författare)
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Term amniotic fluid : An unexploited reserve of mesenchymal stromal cells for reprogramming and potential cell therapy applications
- 2017
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Ingår i: Stem Cell Research and Therapy. - : Springer Science and Business Media LLC. - 1757-6512. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Mesenchymal stromal cells (MSCs) are currently being evaluated in numerous pre-clinical and clinical cell-based therapy studies. Furthermore, there is an increasing interest in exploring alternative uses of these cells in disease modelling, pharmaceutical screening, and regenerative medicine by applying reprogramming technologies. However, the limited availability of MSCs from various sources restricts their use. Term amniotic fluid has been proposed as an alternative source of MSCs. Previously, only low volumes of term fluid and its cellular constituents have been collected, and current knowledge of the MSCs derived from this fluid is limited. In this study, we collected amniotic fluid at term using a novel collection system and evaluated amniotic fluid MSC content and their characteristics, including their feasibility to undergo cellular reprogramming. Methods: Amniotic fluid was collected at term caesarean section deliveries using a closed catheter-based system. Following fluid processing, amniotic fluid was assessed for cellularity, MSC frequency, in-vitro proliferation, surface phenotype, differentiation, and gene expression characteristics. Cells were also reprogrammed to the pluripotent stem cell state and differentiated towards neural and haematopoietic lineages. Results: The average volume of term amniotic fluid collected was approximately 0.4 litres per donor, containing an average of 7 million viable mononuclear cells per litre, and a CFU-F content of 15 per 100,000 MNCs. Expanded CFU-F cultures showed similar surface phenotype, differentiation potential, and gene expression characteristics to MSCs isolated from traditional sources, and showed extensive expansion potential and rapid doubling times. Given the high proliferation rates of these neonatal source cells, we assessed them in a reprogramming application, where the derived induced pluripotent stem cells showed multigerm layer lineage differentiation potential. Conclusions: The potentially large donor base from caesarean section deliveries, the high yield of term amniotic fluid MSCs obtainable, the properties of the MSCs identified, and the suitability of the cells to be reprogrammed into the pluripotent state demonstrated these cells to be a promising and plentiful resource for further evaluation in bio-banking, cell therapy, disease modelling, and regenerative medicine applications.
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