| 1. |
- Wyrick, J., et al.
(författare)
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Do Two-Dimensional "Noble Gas Atoms" Produce Molecular Honeycombs at a Metal Surface?
- 2011
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 11:7, s. 2944-2948
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Tidskriftsartikel (refereegranskat)abstract
- Anthraquinone self-assembles on Cu(111) into a giant honeycomb network with exactly three molecules on each side. Here we propose that the exceptional degree of order achieved in this system can be explained as a consequence of the confinement of substrate electrons in the pores, with the pore size tailored so that the confined electrons can adopt a noble-gas-like two-dimensional quasi-atom configuration with two filled shells. Formation of identical pores in a related adsorption system (at different overall periodicity due to the different molecule size) corroborates this concept. A combination of photoemission spectroscopy with density functional theory computations (including van der Waals interactions) of adsorbate-substrate interactions allows quantum mechanical modeling of the spectra of the resultant quasi-atoms and their energetics.
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| 2. |
- Garbulsky, Martin F., et al.
(författare)
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Patterns and controls of the variability of radiation use efficiency and primary productivity across terrestrial ecosystems
- 2010
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Ingår i: Global Ecology and Biogeography. - : Wiley. - 1466-8238 .- 1466-822X. ; 19:2, s. 253-267
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Tidskriftsartikel (refereegranskat)abstract
- Aim The controls of gross radiation use efficiency (RUE), the ratio between gross primary productivity (GPP) and the radiation intercepted by terrestrial vegetation, and its spatial and temporal variation are not yet fully understood. Our objectives were to analyse and synthesize the spatial variability of GPP and the spatial and temporal variability of RUE and its climatic controls for a wide range of vegetation types. Location A global range of sites from tundra to rain forest. Methods We analysed a global dataset on photosynthetic uptake and climatic variables from 35 eddy covariance (EC) flux sites spanning between 100 and 2200 mm mean annual rainfall and between -13 and 26 degrees C mean annual temperature. RUE was calculated from the data provided by EC flux sites and remote sensing (MODIS). Results Rainfall and actual evapotranspiration (AET) positively influenced the spatial variation of annual GPP, whereas temperature only influenced the GPP of forests. Annual and maximum RUE were also positively controlled primarily by annual rainfall. The main control parameters of the growth season variation of gross RUE varied for each ecosystem type. Overall, the ratio between actual and potential evapotranspiration and a surrogate for the energy balance explained a greater proportion of the seasonal variation of RUE than the vapour pressure deficit (VPD), AET and precipitation. Temperature was important for determining the intra-annual variability of the RUE at the coldest energy-limited sites. Main conclusions Our analysis supports the idea that the annual functioning of vegetation that is adapted to its local environment is more constrained by water availability than by temperature. The spatial variability of annual and maximum RUE can be largely explained by annual precipitation, more than by vegetation type. The intra-annual variation of RUE was mainly linked to the energy balance and water availability along the climatic gradient. Furthermore, we showed that intra-annual variation of gross RUE is only weakly influenced by VPD and temperature, contrary to what is frequently assumed. Our results provide a better understanding of the spatial and temporal controls of the RUE and thus could lead to a better estimation of ecosystem carbon fixation and better modelling.
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| 3. |
- Harter Griep, R, et al.
(författare)
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Beyond simple approaches to studying the association between work characteristics and absenteeism : Combining the DCS and ERI models
- 2010
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Ingår i: Work & Stress. - : Informa UK Limited. - 0267-8373 .- 1464-5335. ; 24:2, s. 179-195
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Tidskriftsartikel (refereegranskat)abstract
- The Demand-Control-Support (DCS) and the Effort-Reward Imbalance (ERI) models assess different psychosocial factors. This study investigates whether a combination of these models increases their ability to predict sickness absence, as compared to results based on each model separately. A cross-sectional study with nursing personnel (N = 1307) in Brazil was performed. Regression analyses were conducted in three stages: analysis of each scale of the models and sickness absences; assessment of the independent association of each model with sickness absences; assessment of the associations of three combinations of models/scales with sickness absences: DC and social support (SS), ERI and overcommitment, and DC and ERI. As regards comparisons between the stress models, ERI was shown to be independently associated with short (up to 9 days) and long (10 days or more) spells of absenteeism. The same result held true for low social support. The combinations DC-ERI and DC-SS were better predictors for short spells than each model/scale separately, whereas for long spells, the combination DC-SS was the best predictor. ERI seems to be a good instrument for predicting absenteeism if used alone, whereas DC performed better when combined with ERI or SS. An improved risk estimation of sickness absences by combining information from the two models was observed.
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