| 1. |
- Thiere, Geraldine, et al.
(author)
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Nitrogen retention versus methane emission : Environmental benefits and risks of large-scale wetland creation
- 2011
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In: Ecological Engineering. - : Elsevier. - 0925-8574 .- 1872-6992. ; 37:1, s. 6-15
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Journal article (peer-reviewed)abstract
- Coastal eutrophication by nutrient fluxes from agricultural land to marine recipients is presently combated by measures such as the implementation of watershed-scale wetland creation programs aimed at nitrogen removal. Such created agricultural wetlands – termed ‘nitrogen farming wetlands’ (NFWs) – receive nitrogen (N) loads predominantly as nitrate, facilitating N removal by denitrification. However, the conversion of agricultural soils into waterlogged wetland area is likely to increase climate gas emissions, particularly methane (CH4). There is thus a need to evaluate the benefits and risks of wetland creation at a large, watershed-scale. Here we investigate N retention and CH4 emission originating from watershed-scale wetland creation in South Sweden, the relation between both processes, and how CH4 emission depends on individual wetland parameters. We combine data from intensively studied reference wetlands with an extensive wetland survey to predict N retention and CH4 emission with simple models, to estimate the overall process rates (large-scale effects) as well as spatial variation among individual NFWs. We show that watershed-scale wetland creation serves targeted environmental objectives (N retention), and that CH4 emission is comparably low. Environmental benefit and risk of individual wetlands were not correlated, and may thus be managed independently. High cover of aquatic plants was the most important wetland property that suppressed CH4 net production, potentially facilitating N retention simultaneously. Further, differences between wetlands in water temperature and wetland age seemed to contribute to differences in CH4 net production. The nationally planned wetland creation (12,000 ha) could make a significant contribution to the targeted reduction of N fluxes (up to 27% of the Swedish environmental objective), at an environmental risk equaling 0.04% of the national anthropogenic climate gas emission.
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| 2. |
- Borschel, Christian, et al.
(author)
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A New Route toward Semiconductor Nanospintronics : Highly Mn-Doped GaAs Nanowires Realized by Ion-Implantation under Dynamic Annealing Conditions
- 2011
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In: Nano letters (Print). - Washington : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 11:9, s. 3935-3940
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Journal article (peer-reviewed)abstract
- We report on highly Mn-doped GaAs nanowires (NWs) of high crystalline quality fabricated by ion beam implantation, a technique that allows doping concentrations beyond the equilibrium solubility limit. We studied two approaches for the preparation of Mn-doped GaAs NWs: First, ion implantation at room temperature with subsequent annealing resulted in polycrystalline NWs and phase segregation of MnAs and GaAs. The second approach was ion implantation at elevated temperatures. In this case, the single-crystallinity of the GaAs NWs was maintained, and crystalline, highly Mn-doped GaAs NWs were obtained. The electrical resistance of such NWs dropped with increasing temperature (activation energy about 70 meV). Corresponding magnetoresistance measurements showed a decrease at low temperatures, indicating paramagnetism. Our findings suggest possibilities for future applications where dense arrays of GaMnAs nanowires may be used as a new kind of magnetic material system.
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| 3. |
- Shang, X. -J, et al.
(author)
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Quantum-dot-induced optical transition enhancement in InAs quantum-dot-embedded p-i-n GaAs solar cells
- 2011
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In: Applied Physics Letters. - New York, N.Y. : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 99:11, s. 113514-113514-3
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Journal article (peer-reviewed)abstract
- Photocurrents (PCs) of three p–i–n GaAs solar cells, sample A with InAs quantum dots (QDs) embedded in the depletion region, B with QDs in the n region, and C without QDs, were studied experimentally and theoretically. Above GaAs bandgap, the PC of A is increased, while B is decreased with respect to C, since in A, the QD-induced reflection of hole wave function increases its overlap with electron wave function so that the optical transition rate is enhanced, while carrier mobility in B is reduced due to QD-induced potential variations. Moreover, A and B have increased PCs in the sub-GaAs-bandgap range due to QD optical absorptions.
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| 4. |
- Suyatin, Dmitry, et al.
(author)
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Nano-Schottky contacts realized by bottom-up technique
- 2010
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In: INEC 2010 - 2010 3rd International Nanoelectronics Conference, Proceedings. - Piscataway, N.J. : IEEE Press. - 9781424435432 ; , s. 252-253
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Conference paper (peer-reviewed)abstract
- Properties of nanostructures realized by bottom-up techniques are often different from their bulk counterparts. Here we present a study of a nano-Schottky contact formed at the interface between a gold catalytic particle and an epitaxially grown GaxIn1-xAs/InAs nanowire. Selective electrical connections formed to the catalytic particle on one side and to the InAs segment on the other side allowed electrical and optical characterization of the formed junction. We demonstrate that the heterostructure region adjacent to the catalytic particle may act as an ultra-small volume unipolar photodetector with potentially ultra-fast response.
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| 5. |
- Wittwer, Torben, et al.
(author)
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Does one community shape the other? Dragonflies and fish in Swedish lakes
- 2010
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In: Insect Conservation and Diversity. - London : Wiley. - 1752-4598 .- 1752-458X. ; 3:2, s. 124-133
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Journal article (peer-reviewed)abstract
- 1. Freshwater communities are often structured by predation. In permanent lentic freshwater habitats dragonfly larvae are major predators which, in return, suffer predation by fish. Antipredator traits vary between the dragonfly species, and the dragonfly communities are therefore shaped by the presence of fish. But fish communities vary, and as different fish species affect dragonflies in different ways, the species composition of the fish community may affect the composition of the dragonfly community. 2. We sampled dragonfly larvae in 24 lakes with a known fish stock in south-western Sweden, and explored the impact of fish as well as vegetation structure on dragonfly communities by means of multivariate analyses. 3. We found that the presence of four fish species affected the community structure of dragonflies. The impact strength depended mainly on the abundance of Perca fluviatilis, with which most dragonfly species were negatively correlated. Many dragonfly species were also positively correlated with the occurrence of at least one fish species, which may reflect similar habitat requirements or imply indirect positive effects of these fish species. 4. Of the 24 recorded dragonfly species, four did not occur in lakes dominated by P. fluviatilis, whereas only one species was lacking in lakes dominated by Rutilus rutilus. The dragonfly species diversity was higher in R. rutilus lakes than in P. fluviatilis lakes. 5. Our results suggest that the fish species composition is a major determinant of the dragonfly community, which in turn will influence the lower trophic levels.
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| 6. |
- Cronquist, Björn, et al.
(author)
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The CILO method : firm-supportive research approach enhancing enterprise performance
- 2010
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In: Knowledge Management and Innovation. - : International Business Information Management Association (IBIMA). ; , s. 1239-1251, s. 1239-1251
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Conference paper (peer-reviewed)abstract
- This paper describes a case of collaboration between academia and business firms in supporting innovation processes based on the CILO method, named after the CILO project (communication in learning organizations). The CILO method is an example of firm-supportive research approach. We describe the outcomes related to enhancing enterprise performance from applying the CILO-method in relation to one of the partner companies. The aim of the paper is to describe and discuss the concept of firm-supportive research in relation to the concept of innovation and to demonstrate how the specific characteristics of this research approach can enhance enterprise performance in one of our partner companies, Flower Systems Ltd.
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| 7. |
- Karlsson, Maria, et al.
(author)
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Continuous and stepwise oocyte production in Libellulidae (Anisoptera)
- 2010
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In: Odonatologica. - Utrecht, Netherlands : Societas Internationalis Odonatologica. - 0375-0183. ; 39:2, s. 107-119
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Journal article (peer-reviewed)abstract
- Compared to other insect groups, libellulids have a rather high mean number of ovarioles. In addition, the mean ovariole diameter differs greatly between and within species. In general, 2 different types of ovariole arrangement exist: (1) all developing oocytes mature and equal in size; in some species without, and in others with, surrounding connective tissue and (2) oocytes displaying gradual maturation, with only the outermost ovarioles mature. These differences have ecological consequences: the first arrangement occurs in spp. that have stepwise egg production. These spp. will lay one or more clutches, after which an interclutch interval of ovariole regrowth follows. Spp. with the second arrangement have continuous egg production and are able to lay at least some eggs all the time, reducing the length of interclutch intervals. However, no direct connection between mate-guarding strategies and ovariole arrangements can be seen. Nevertheless, it is believed that the process of ovariole maturation differs between these groups. It is concluded that ovary morphology in libellulids may exhibit evolutionary fixed traits, although the whole picture still remains complex. The ovariole arrangement may have a crucial impact on the reproductive ecology of the species.
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| 8. |
- Larsson, Tony, et al.
(author)
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Dependable Automotive Systems based on Model Certified Components
- 2011
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Conference paper (peer-reviewed)abstract
- Advances in Intelligent Transport Systems (ITS), intelligent vehicles and cooperative systems are enabling traffic and transport solutions that are both safer and more environmentally acceptable. While it is well known that high dependability is a desirable feature it has a price, and the level of dependability needed varies from application to application. Typical examples are cooperative safety applications, in particular traffic situation aware vehicle driver warning and assisting systems, enabled by vehicle-to-vehicle and vehicle-to-infrastructure wireless communication in combination with the use of geographical map information, Differential Global Positioning System (DGPS) and vehicle-carried sensors. This kind of applications depend on the reception of satellite data (combined with on-board sensor data from, e.g. odometer and accelerometer) for positioning of the own vehicle and on periodic broadcasting of this information to all neighbors in range. Both the wireless communication with satellites and the one between vehicles can have severe difficulties, for example due to hills or high buildings directly hindering both kinds of radio transmission. There are techniques to make the solutions more robust, e.g. by information fusion for temporary or local communication outage compensation. However, further development is needed and since coverage problems can be made known in advance and related to geographical areas, such information can also be explored.
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| 9. |
- Boberg, Pelle, et al.
(author)
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The effect of high temperatures on seed germination of one native and two introduced conifers in Patagonia
- 2010
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In: Nordic Journal of Botany. - Chichester : Wiley-Blackwell. - 0107-055X .- 1756-1051. ; 28:2, s. 231-239
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Journal article (peer-reviewed)abstract
- We examined the effect of thermal shock on the germination of seeds of three conifers, two introduced (Pseudotsuga menziesii and Pinus ponderosa), and one native to Patagonia (Araucaria araucana). Previous research has suggested increased susceptibility to invasions in burnt areas, and therefore, the effect of simulated fire (heat) on seed germination in these native and introduced species was compared. Seeds were heated to two different heat intensities (50°C and 100°C) for 1 or 5 min, which is within the temperature range reached in the upper soil layers during forest fires. Germination tests were then carried out in a growth chamber. The heat treatments had a negative effect on the germination of P. menziesii at temperatures of 100°C, and a negative effect on the germination of P. ponderosa at the temperature of 100°C and the exposure of 5 min. The heat treatments had no affect at all on A. araucana. The species with larger seeds (A. araucana) had higher survival rates after the thermal shocks. Also intraspecific differences in seed sizes possibly point at larger seeds surviving thermal shocks better than smaller seeds. In addition, thermal shock caused a delay in the onset of germination in the two introduced species, while it did not change the time for germination in A. araucana. © The Authors. Journal compilation © Nordic Journal of Botany 2010.
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| 10. |
- Conache, Gabriela, et al.
(author)
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Bias-controlled friction of InAs nanowires on a silicon nitride layer studied by atomic force microscopy
- 2010
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In: Physical Review B Condensed Matter. - College Park, Md. : American Physical Society. - 0163-1829 .- 1095-3795. ; 82:3
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Journal article (peer-reviewed)abstract
- By studying how nanowires lying on a surface bend when pushed by an atomic force microscopy tip we are able to measure the friction between them and the substrate. Here, we show how the friction between InAs nanowires and an insulating silicon nitride layer varies when a dc voltage is applied to the tip during manipulation. The bias charges the capacitor formed by the wire and the grounded silicon back contact. Electrostatic forces increase the contact pressure and allow us to tune the friction between the wire and the silicon nitride surface. Using nanowires of about 40-70 nm diameter and a few microns in length we have applied biases in the range +12 to -12 V. A monotonic increase of the sliding friction with voltage was observed. This increase in friction with the normal force implies that the mesoscopic nanowire-surface system behaves like a macroscopic contact, despite the nanometer size of the contact in the direction of motion. The demonstrated bias-controlled friction has potential applications in MEMS/NEMS devices.
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