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- Klein, Josefin, et al.
(author)
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Modeling Potential Water Resource Impacts of Mediterranean Tourism in a Changing Climate
- 2015
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In: Environmental Modelling and Assessment. - : Springer Science and Business Media LLC. - 1420-2026 .- 1573-2967. ; 20:2, s. 117-128
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Journal article (peer-reviewed)abstract
- A scenario analysis was conducted to explore the impacts of climate and land-water management changes using an 89-km(2) catchment near the Navarino Environmental Observatory (NEO) located in southwestern Messenia, Greece, as a regionally representative case study. Our objective was to quantify potential impacts on groundwater storage and streamflow at the catchment scale. To achieve this, the simple Thornthwaite-Mather-based hydrological model was calibrated to 3 years of available data (2009-2011) and used to explore the following: (1) impacts of climate change (specifically, IPCC's A2 and B2 projections for 2071-2100), (2) impacts of land-water management changes associated with expansion of tourism activities (specifically, the addition of irrigated golf courses), and (3) the combined impact of both climate and land-water management changes. The model results indicated potential vulnerability of water resources to future climate change which could, for example, reduce streamflow between 33 and 97 % of current annual flows depending on the scenario considered. Future land-water management change could also reduce streamflow (under the current climate) by 3 or 5 % depending on if the change involves export of water outside the catchment. Clearly, this would be exacerbated under coupled climate changes which highlights the importance of environmental monitoring (part of the mission of the NEO) to inform management and planning in this and other Mediterranean regions.
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- Külheim, Carsten, 1976-
(author)
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The significance of feedback de-excitation
- 2005
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Doctoral thesis (other academic/artistic)abstract
- During photosynthesis sunlight is absorbed by photosynthetic pigments and converted into organic compounds, such as carbohydrates. Photosynthesis needs to be highly regulated, since both too much and too little light are harmful to plant. If too little light is absorbed, a plant cannot store enough energy, which will have effects on growth and fitness of the plant. With too much light absorbed, a dangerous side reaction of photosynthesis, the production of reactive oxygen species can happen. These reactive oxygen species can damage the proteins in the chloroplast and the lipids of the chloroplast. To avoid the production of reactive oxygen species, plants have evolved many mechanisms, which act on different time-scales and different levels of organization. As a first measure, when the absorbed light is exceeding the capacity for its utilization, is to switch the light-harvesting antenna from efficient light harvesting to energy dissipation. This process is called feedback de-excitation (FDE). The protein PsbS is essential for this process as well as a functioning xanthophylls cycle with the enzyme violaxanthin de-epoxidase (VDE). I have investigated the effects of plants with changes in their ability to dissipate excess excitation energy in the model plants species Arabidopsis thaliana. Three genotypes with either increased or decreased capacity for FDE were used during my experiments. The first genotype over-expresses the PsbS gene, having approximately two-fold increased amounts of PsbS and FDE. The second is a PsbS deletion mutant with no PsbS protein and no FDE. The third genotype cannot perform the conversion of violaxanthin to zeaxanthin, because the enzyme VDE is missing. This mutant has some FDE left. Arabidopsis thaliana is an annual plant, which flowers only once in its lifetime. Therefore, when counting the seeds produced an estimation of fitness can be made from the amount of seeds produced. This was done during my experiments and shown that FDE is a trait and that plants with increased FDE have a higher fitness and vice versa. This was also the case for a collection of plants lacking a single protein from the light harvesting antenna. All of these genotypes had a fitness reduction, proving that their function is not redundant. In an attempt to explain why the fitness is reduced in plants with altered FDE, photosynthetic measurements, as well as a determination of the transcriptome and the metabolome was performed. Plants lacking FDE had higher levels of photoinhibition, leading both to lower rates of photosynthesis and to higher repair cost. This could in part explain the reduction in fitness. These plants also had major changes in their transcriptome and their metabolome. Primary metabolism was most effected, for example carbohydrate and amino acid metabolism. But there were also changes in secondary metabolism such as an up regulation of the biosynthesis of anthocyanins.
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- Pramling Samuelsson, Ingrid, 1946
(author)
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Barns perspektiv vid dokumentation - en chimär eller möjlighet
- 2001
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In: Förskoletidningen. ; :4, s. 13-16
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Journal article (other academic/artistic)abstract
- Jag har i andra sammanhang hävdat att ”barns perspektiv” utgör ett centralt tema i alla nyare teorier om barn och barns lärande. Innebär detta att vi håller på att få ett nytt universellt eller generellt perspektiv trots att hela den postmoderna teoribildningen argumenterar mot generella teorier? Eller vad betyder det att man idag överallt kan läsa att barns perspektiv skall vara utgångspunkt för pedagogisk verksamhet?
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- Rolt, Andrew, et al.
(author)
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Scale effects on conventional and intercooled turbofan engine performance
- 2017
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In: Aeronautical Journal. - : Cambridge University Press (CUP). - 0001-9240 .- 2059-6464. ; 121:1242, s. 1162-1185
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Journal article (peer-reviewed)abstract
- New commercial aero engines for 2050 are expected to have lower specific thrusts for reduced noise and improved propulsive efficiency, but meeting the ACARE Flightpath 2050 fuel-burn and emissions targets will also need radical design changes to improve core thermal efficiency. Intercooling, recuperation, inter-turbine combustion and added topping and bottoming cycles all have the potential to improve thermal efficiency. However, these new technologies tend to increase core specific power and reduce core mass flow, giving smaller and less efficient core components. Turbine cooling also gets more difficult as engine cores get smaller. The core-size-dependent performance penalties will become increasingly significant with the development of more aerodynamically efficient and lighter-weight aircraft having lower thrust requirements. In this study the effects of engine thrust and core size on performance are investigated for conventional and intercooled aeroengine cycles. Large intercooled engines could have 3%-4% SFC improvement relative to conventional cycle engines, while smaller engines may only realize half of this benefit. The study provides a foundation for investigations of more complex cycles in the EU Horizon 2020 ULTIMATE programme.
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- Van Boening, Mark, et al.
(author)
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Benefit packages and individual behavior : Choices over discrete goods with multiple attributes
- 2006
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In: Managerial and Decision Economics. - : John Wiley & Sons. - 0143-6570 .- 1099-1468. ; 27:6, s. 511-526
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Journal article (peer-reviewed)abstract
- Managers and employers use an array of rewards to attract and retain quality employees. An increasingly significant component of the overall compensation is the employee's benefits package. Flexible packages offer more choice but also incur higher decision costs. We conduct an experiment on choices over stylized benefits packages where discrete 'goods' have multiple attributes affecting the payoff function. We investigate the degree to which these complications affect choices. Eighty subjects play an individual-choice decision-cost game where they are implicitly asked to solve a complex programming problem. Our main results are that: (a) individual subjects respond to the relative tradeoff between the attributes, (b) some combinations of the attributes (apparently) entice subjects to search more and thus earn more, and (c) most subjects appear to adopt a heuristic that approximates the optimal solution. Further, subjects appear to value the right to make choices, as they rarely choose a fixed payoff option with a known payoff and low decision cost, even when the fixed payoff is 80% of the maximum possible under the decision-making task.
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| 9. |
- Van Bogaert, Rik, et al.
(author)
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A century of tree line changes in sub-Arctic Sweden shows local and regional variability and only a minor influence of 20th century climate warming
- 2011
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In: Journal of Biogeography. - : Wiley. - 0305-0270 .- 1365-2699. ; 38:5, s. 907-921
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Journal article (peer-reviewed)abstract
- Aim Models project that climate warming will cause the tree line to move to higher elevations in alpine areas and more northerly latitudes in Arctic environments. We aimed to document changes or stability of the tree line in a sub-Arctic model area at different temporal and spatial scales, and particularly to clarify the ambiguity that currently exists about tree line dynamics and their causes. Location The study was conducted in the Tornetrask area in northern Sweden where climate warmed by 2.5 degrees C between 1913 and 2006. Mountain birch (Betula pubescens ssp. czerepanovii) sets the alpine tree line. Methods We used repeat photography, dendrochronological analysis, field observations along elevational transects and historical documents to study tree line dynamics. Results Since 1912, only four out of eight tree line sites had advanced: on average the tree line had shifted 24 m upslope (+0.2 m year-1 assuming linear shifts). Maximum tree line advance was +145 m (+1.5 m year-1 in elevation and +2.7 m year-1 in actual distance), whereas maximum retreat was 120 m downslope. Counter-intuitively, tree line advance was most pronounced during the cooler late 1960s and 1970s. Tree establishment and tree line advance were significantly correlated with periods of low reindeer (Rangifer tarandus) population numbers. A decreased anthropozoogenic impact since the early 20th century was found to be the main factor shaping the current tree line ecotone and its dynamics. In addition, episodic disturbances by moth outbreaks and geomorphological processes resulted in descent and long-term stability of the tree line position, respectively. Main conclusions In contrast to what is generally stated in the literature, this study shows that in a period of climate warming, disturbance may not only determine when tree line advance will occur but if tree line advance will occur at all. In the case of non-climatic climax tree lines, such as those in our study area, both climate-driven model projections of future tree line positions and the use of the tree line position for bioclimatic monitoring should be used with caution.
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