| 1. |
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Jones, Owen R., et al.
(författare)
-
Senescence rates are determined by ranking on the fast-slow life-history continuum
- 2008
-
Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 11:7, s. 664-673
-
Tidskriftsartikel (refereegranskat)abstract
- Comparative analyses of survival senescence by using life tables have identified generalizations including the observation that mammals senesce faster than similar-sized birds. These generalizations have been challenged because of limitations of life-table approaches and the growing appreciation that senescence is more than an increasing probability of death. Without using life tables, we examine senescence rates in annual individual fitness using 20 individual-based data sets of terrestrial vertebrates with contrasting life histories and body size. We find that senescence is widespread in the wild and equally likely to occur in survival and reproduction. Additionally, mammals senesce faster than birds because they have a faster life history for a given body size. By allowing us to disentangle the effects of two major fitness components our methods allow an assessment of the robustness of the prevalent life-table approach. Focusing on one aspect of life history - survival or recruitment - can provide reliable information on overall senescence.
|
|
| 5. |
- Ottosen, Lisbeth M., et al.
(författare)
-
Electrodialytic remediation of soil slurry-removal of Cu, Cr, and As
- 2009
-
Ingår i: Separation science and technology (Print). - Philadelphia, PA : Taylor & Francis. - 0149-6395 .- 1520-5754. ; 44:10, s. 2245-2268
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Severe soil contamination is often found at old wood preservation sites and a common combination of pollutants is Cu, Cr, and As. In the present work it is tested if simultaneous removal of Cu, Cr, and As can be obtained in an electrodialytic cell where the polluted soil is remediated as a stirred suspension (placed as the desalination compartment in accordance to the position of the ion exchange membranes). The soil for the experiments was sampled at an abandoned wood preservation site and contained 2170mg Cu/kg, 710mg Cr/kg and 3200mg As/kg. SEM-EDX analysis showed that Cu, Cr, As and oxygen formed particles that were cementing soil minerals together. The soil was suspended in distilled water, distilled water with I2 crystals to have an oxidizing environment, or in an acidified environment at pH about 1.0. The experiments lasted from 1 to 3 weeks. Good results were obtained in two experiments; an experiment where the soil was suspended in distilled water and the remediation lasted 3 weeks with 2.5mA and an experiment with acidification of the soil suspension with HNO3 to pH about 1.0 (2 weeks and 5mA). The best separation of pollutants and soil was obtained in the experiment with suspension in distilled water. Based on soil concentrations, good Cu removal (95%) was obtained in both experiments. Removal of Cr was most efficient from the acidified soil suspension (74%). Both Cu and Cr concentrations were below the limiting values after the remediation. The As concentration, however, was not even although 61% was removed. In the soil remained about 1070mg As/kg soil and since the limiting value is 40mg As/kg, the removal was not efficient enough. So simultaneous removal was possible, but the target values were only met in the case of Cu and Cr, and more research is needed to remove As to a sufficiently low concentration, as well.
|
|
| 6. |
- Steffensen, Jörgen Peder, et al.
(författare)
-
High-Resolution Greenland Ice Core Data Show Abrupt Climate Change Happens in Few Years
- 2008
-
Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 321, s. 680-684
-
Tidskriftsartikel (refereegranskat)abstract
- The last two abrupt warmings at the onset of our present warm interglacial period, interrupted bythe Younger Dryas cooling event, were investigated at high temporal resolution from the NorthGreenland Ice Core Project ice core. The deuterium excess, a proxy of Greenland precipitationmoisture source, switched mode within 1 to 3 years over these transitions and initiated a moregradual change (over 50 years) of the Greenland air temperature, as recorded by stable waterisotopes. The onsets of both abrupt Greenland warmings were slightly preceded by decreasingGreenland dust deposition, reflecting the wetting of Asian deserts. A northern shift of theIntertropical Convergence Zone could be the trigger of these abrupt shifts of Northern Hemisphereatmospheric circulation, resulting in changes of 2 to 4 kelvin in Greenland moisture sourcetemperature from one year to the next.
|
|
| 7. |
- Zettergren, Henning, et al.
(författare)
-
Fragmentation and ionization of C70 and C60 by slow ions of intermediate charge
- 2006
-
Ingår i: European Physical Journal D. - : Springer. - 1434-6060 .- 1434-6079. ; 38:2, s. 299-306
-
Tidskriftsartikel (refereegranskat)abstract
- We have measured total and coincident (with outgoing charge-state analyzed projectiles) ionization and fragmentation spectra of C 60 and C70 following collisions with Xe4+ and Kr4+ at v = 0. 06 a.u. Intact positive fullerene ions in charge states up to five (C 5+ 60 and C 5+ 70 ) are produced with both projectiles and for Kr 4++C70 collisions we even observe a small C 6+ 70 peak. The C 3+ 60 /70−2m (m = 1–7) intensity distributions are predominantly associated with the stabilization of three electrons on the projectile ( s = 3) and are significantly different for Xe 4+- and Kr4+ -projectiles. On the other hand, we find remarkable similarities in the C + 3 -C + 11 multi-fragmentation pattern regardless of projectile species (mass) although they are associated with closer encounters in which the projectile is fully neutralized ( s = 4). Simple Monte Carlo calculations of nuclear and electronic loss processes show that both these contributions are very similar in glancing Xe 4++C60 and Kr4++C60 collisions, suggesting that frontal (and more violent) collisions are strongly suppressed under the present experimental conditions. Nevertheless it is surprising that the more distant collisions ( s = 3) are projectile mass dependent, while the closer collisions (s = 4) are not. This indicates that this simple approach (although it reproduces more advanced quantum mechanical calculations for slow collisions with singly charged atomic ions rather well) is not valid for a comprehensive description of the energy transfer processes in the present collision systems involving projectiles of higher charge states.
|
|
