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| 2. |
- Cunningham, J.A., et al.
(författare)
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Maturing Out of Drinking Problems : Perceptions of Natural History as a Function of Severity
- 2005
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Ingår i: Addiction Research and Theory. - : Informa UK Limited. - 1058-6989 .- 1606-6359 .- 1476-7392. ; 13:1, s. 79-84
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Tidskriftsartikel (refereegranskat)abstract
- This study tested the hypothesis that maturing out descriptions of change were more common among respondents whose drinking problems were less severe prior to reduction and that consequence driven changes were more common among those who had a lifetime diagnosis of alcohol dependence, prior to resolution. As part of a general population telephone survey, former heavy drinkers were asked their reasons for change. These responses were tape-recorded, transcribed and then coded into three categories – consequence driven reasons, drifting out reasons and reflective maturational reasons. As predicted, drifting out reasons were more often provided by those with less severe alcohol use and consequence related reasons appeared associated with respondents who had had more severe alcohol problems. The differing descriptions of pathways to change observed in natural history studies may be the result of research that captures only partial samples of the larger population of former heavy drinkers.
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| 3. |
- Walker, M. D., et al.
(författare)
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Plant community responses to experimental warming across the tundra biome
- 2006
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 103:5, s. 1342-1346
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Tidskriftsartikel (refereegranskat)abstract
- Recent observations of changes in some tundra ecosystems appear to be responses to a warming climate. Several experimental studies have shown that tundra plants and ecosystems can respond strongly to environmental change, including warming; however, most studies were limited to a single location and were of short duration and based on a variety of experimental designs. In addition, comparisons among studies are difficult because a variety of techniques have been used to achieve experimental warming and different measurements have been used to assess responses. We used metaanalysis on plant community measurements from standardized warming experiments at 11 locations across the tundra biome involved in the International Tundra Experiment. The passive warming treatment increased plant-level air temperature by 1-3 degrees C, which is in the range of predicted and observed warming for tundra regions. Responses were rapid and detected in whole plant communities after only two growing seasons. Overall, warming increased height and cover of deciduous shrubs and graminoids, decreased cover of mosses and lichens, and decreased species diversity and evenness. These results predict that warming will cause a decline in biodiversity across a wide variety of tundra, at least in the short term. They also provide rigorous experimental evidence that recently observed increases in shrub cover in many tundra regions are in response to climate warming. These changes have important implications for processes and interactions within tundra ecosystems and between tundra and the atmosphere.
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| 4. |
- Anisimov, O., et al.
(författare)
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Permafrost
- 2009
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Ingår i: Melting snow and ice: a call for action.. - 9788276662641 ; , s. 64-71
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 5. |
- Armstrong, R., et al.
(författare)
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Snow
- 2009
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Ingår i: Melting snow and ice – a call for action. - 9788276662641 ; , s. 24-31
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 6. |
- Blute, Irena, et al.
(författare)
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Industrial manufactured silica nanoparticle sols. 2 : Surface tension, particle concentration, foam generation and stability
- 2009
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Ingår i: Colloids and Surfaces A. - : Elsevier BV. - 0927-7757 .- 1873-4359. ; 337:1-3, s. 127-135
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Tidskriftsartikel (refereegranskat)abstract
- Several earlier papers have revealed that several key parameters, such as hydrophobicity (contact angle), size, shape and degree of agglomeration, have an important influence on the behavior of particles at the air/water interface. However, the origin of foaming with particles is still not clear. In this article, we have tentatively related surface tension measurements and particle concentrations to the generation and stability of foam produced from industrial manufactured silica nanoparticle sols. Surprisingly, only slight reductions in surface tension were observed and the differences between the hydrophophilic and partially modified hydrophobic sols were small. However, in the case of the partially modified hydrophobic sol, the surface tension/concentration gradient was found to be pH and concentration responsive. Also, the greatest reduction in Surface tension was found to occur at low pH (in the region of the pH(pzc)) and could be related to the highest foamability (foam generation) as determined in our earlier publication [1. Blute, R.J. Pugh, J. van de Pas, I. Callaghan, Silica nanoparticle sols. 1. Surface chemical characterization and evaluation of the foam generation (foamability), J. Colloid Interface Sci. 313 (2007) 645-655]. Also, after centrifugation of the moderately hydrophobic modified concentrated sols, foaming tests carried out on the supernatant indicated that the particle concentration had a dominant influence on foamability and foam stability. Since only transient foams, with relatively short lifetimes, could be produced with these modified silica nanoparticles then (a) further surface modification or the reduction of pH to increase the Surface activity or (b) the addition of a cosurfactant Would be needed to increase the foamability and achieve foams with extended lifetimes.
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| 7. |
- Blute, Irena, et al.
(författare)
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Silica nanoparticle sols 1 : Surface chemical characterization and evaluation of the foam generation (foamability)
- 2007
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 0021-9797 .- 1095-7103. ; 313:2, s. 645-655
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Tidskriftsartikel (refereegranskat)abstract
- Surface characterization and foaming studies were carried out with nine industrially manufactured, colloidal silica dispersions with particles sizes from 5-40 nm. All the silica sols produced transient foams with short decay times and the dynamic foam generation (foamability) was found to vary according to the sol type with the greatest foamability occurring for the hydrophobically modified sol and the deionized hydrophilic sol. However, it was found that improved foamability of all the sols could be achieved by changing the pH to within the region of the pH(pzc) which corresponds to the region of lowest hydrophilicity. An increase in pH (and build-up of negative charge) enhances the surface hydrophilicity and caused a decrease in foamability. In addition, for selected hydrophilic sols, it was shown that the foamability (a) increased with decrease in particle size (within the 6-40 nm range) and (b) increased with particle concentration (within the range of 1-15 wt%). Overall, it was concluded that the foamability was primary controlled by hydrophobicity (and hence by pH) and also by the particle concentration, the particle size and the degree of agglomeration.
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| 8. |
- Blute, Irena, et al.
(författare)
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Silica nanoparticle sols. Part 3 : Monitoring the state of agglomeration at the air/water interface using the Langmuir-Blodgett technique
- 2009
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 0021-9797 .- 1095-7103. ; 336:2, s. 584-591
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Tidskriftsartikel (refereegranskat)abstract
- Langmuir-Blodgett films were prepared at the air/water interface from dispersions of hydrophilic and partially, hydrophobically modified industrially manufactured silica nanoparticles. The hydrophilic particles featured expanded, fairly easily compressible, surface pressure (pi)-area (A) isotherms with well defined collapse pressures which appeared to be caused by the formation of loosely structured agglomerates which exhibited elastic behavior at low surface pressure and inelastic behavior at high surface pressure. Lateral electrostatic interparticle interactions seemingly played an important role in this hydrophilic system. This contrasted with the hydrophobically modified particles which were more difficult to disperse in the ethanol/chloroform spreading solvent and appeared to be in the semi-agglomerated state at low surface pressures and exhibited a more difficult to compress compacted film. Both types of particulate films were shown to be sensitive to the spreading environment and changes in pH were found to increase particle agglomeration which drastically reduced the particulate area for the hydrophilic sol but less so, in the case of the moderately hydrophobically modified sol. In general, the LB technique proved to be a useful method to monitor changes in the state of aggregation of narrosized silica particles at the air/water interface. These results also appear to give some support of our ideas, presented in earlier publications [1,2] in which it was suggested that the major role of the hydrophobically modified hydrophilic particles in foaming was to produce an aggregated particulate film surrounding the air/water interface which provides a physical barrier preventing coalescence of bubbles.
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| 9. |
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| 10. |
- Cornelissen, Johannes H C, et al.
(författare)
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Global negative vegetation feedback to climate warming responses of leaf litter decomposition rates in cold biomes
- 2007
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 10:7, s. 619-627
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Tidskriftsartikel (refereegranskat)abstract
- Whether climate change will turn cold biomes from large long-term carbon sinks into sources is hotly debated because of the great potential for ecosystem-mediated feedbacks to global climate. Critical are the direction, magnitude and generality of climate responses of plant litter decomposition. Here, we present the first quantitative analysis of the major climate-change-related drivers of litter decomposition rates in cold northern biomes worldwide.Leaf litters collected from the predominant species in 33 global change manipulation experiments in circum-arctic-alpine ecosystems were incubated simultaneously in two contrasting arctic life zones. We demonstrate that longer-term, large-scale changes to leaf litter decomposition will be driven primarily by both direct warming effects and concomitant shifts in plant growth form composition, with a much smaller role for changes in litter quality within species. Specifically, the ongoing warming-induced expansion of shrubs with recalcitrant leaf litter across cold biomes would constitute a negative feedback to global warming. Depending on the strength of other (previously reported) positive feedbacks of shrub expansion on soil carbon turnover, this may partly counteract direct warming enhancement of litter decomposition.
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