| 2. |
- Schipper, Aafke M., et al.
(författare)
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Contrasting changes in the abundance and diversity of North American bird assemblages from 1971 to 2010
- 2016
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 22:12, s. 3948-3959
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Tidskriftsartikel (refereegranskat)abstract
- Although it is generally recognized that global biodiversity is declining, few studies have examined long-term changes in multiple biodiversity dimensions simultaneously. In this study, we quantified and compared temporal changes in the abundance, taxonomic diversity, functional diversity, and phylogenetic diversity of bird assemblages, using roadside monitoring data of the North American Breeding Bird Survey from 1971 to 2010. We calculated 12 abundance and diversity metrics based on 5-year average abundances of 519 species for each of 768 monitoring routes. We did this for all bird species together as well as for four subgroups based on breeding habitat affinity (grassland, woodland, wetland, and shrubland breeders). The majority of the biodiversity metrics increased or remained constant over the study period, whereas the overall abundance of birds showed a pronounced decrease, primarily driven by declines of the most abundant species. These results highlight how stable or even increasing metrics of taxonomic, functional, or phylogenetic diversity may occur in parallel with substantial losses of individuals. We further found that patterns of change differed among the species subgroups, with both abundance and diversity increasing for woodland birds and decreasing for grassland breeders. The contrasting changes between abundance and diversity and among the breeding habitat groups underscore the relevance of a multifaceted approach to measuring biodiversity change. Our findings further stress the importance of monitoring the overall abundance of individuals in addition to metrics of taxonomic, functional, or phylogenetic diversity, thus confirming the importance of population abundance as an essential biodiversity variable.
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| 3. |
- Nåbo, L. J., et al.
(författare)
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Computational Approach to Evaluation of Optical Properties of Membrane Probes
- 2017
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Ingår i: Journal of Chemical Theory and Computation. - : American Chemical Society (ACS). - 1549-9618 .- 1549-9626. ; 13:2, s. 719-726
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Tidskriftsartikel (refereegranskat)abstract
- Computed optical properties of membrane probes are typically evaluated in the gas phase, i.e. neglecting the influence of the membrane. In this study, we examine how and to what extent a membrane influences the one- and two-photon absorption (1PA and 2PA, respectively) properties for a number of cholesterol analogs and thereby also evaluate the validity of the common gas phase approach. The membrane is modeled using the polarizable embedding scheme both with and without the effective external field extension of the polarizable embedding model. The shifts in excitation energies and 1PA oscillator strengths compared to the gas phase are relatively small, while the 2PA cross section is more affected. The electric field inside the membrane induces a larger change in the permanent electric dipole moment upon excitation of the analogs compared to the gas phase, which leads to an almost 2-fold increase in the 2PA cross section for one cholesterol analog. The relative trends observed in the membrane are the same as in the gas phase, and the use of gas phase calculations for qualitative comparison and design of cholesterol membrane probes is thus a useful and computationally efficient strategy.
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