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- Semadeni-Davies, Annette, et al.
(författare)
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Northern Research Basins Preface
- 2005
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Ingår i: Proceedings of the 15th northern research basins international symposium and workshop. - Lund : Department of Water Resources Engineering, Lund University.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 5. |
- Adolfsson, Göran, 1981, et al.
(författare)
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Direct observation of lateral carrier diffusion in ridge waveguide InGaNAs lasers
- 2009
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Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 21:134, s. 134-136
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Tidskriftsartikel (refereegranskat)abstract
- We present results from measurements of the subthreshold lateral spontaneous emission profile in 1.3-mu m wavelength ridge waveguide InGaNAs quantum-well lasers using a scanning near-field optical microscopy technique. The measurements reveal the presence of significant lateral carrier diffusion which has a profound effect on the temperature dependence of the threshold current. This effect is frequently omitted when the characteristic temperature of the threshold current is considered.
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| 6. |
- Adolfsson, Göran, 1981, et al.
(författare)
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Effects of Lateral Diffusion on the Temperature Sensitivity of the Threshold Current for 1.3 um Double Quantum-Well GaInNAs/GaAs Lasers
- 2008
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Ingår i: IEEE Journal of Quantum Electronics. ; 44:7, s. 607-616
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Tidskriftsartikel (refereegranskat)abstract
- We present an experimental and theoretical investigationof the temperature dependence of the threshold current fordouble quantum well GaInNAs–GaAs lasers in the temperaturerange 10 C–110 C. Pulsed measurements of the threshold current have been performed on broad and narrow ridge wave guide(RWG) lasers. The narrow RWG lasers exhibit high characteristic temperatures (T0)of 200 K up to a critical temperature (Tc), above which T0 is reduced by approximately a factor of 2. The T0-values for broad RWG lasers are significantly lower than those for the narrow RWG lasers, with characteristic temperatures on the order of 100 (60) K below (above). Numerical simulations, using a model that accounts for lateral diffusion effects, show good agreement with experimental data and reveal that a weakly temperature dependent lateral diffusion current dominates thethreshold current for narrow RWG lasers.
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| 8. |
- Alén, Claes, 1949, et al.
(författare)
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Lime/Cement Column Stabilised Soil - A New Model for settlement calculation
- 2005
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Ingår i: Deep Mixing '05.
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Konferensbidrag (refereegranskat)abstract
- A new model for calculation of settlements for an embankment on lime/cement stabilised clay is presented. The model can be regarded as a development of the current Swedish practice, which is based upon a simplified model, adopted in the computer program Limeset. The goal has been to incorporate recent years experience and research in a qualitative and realistic way. The model is based on the assumption that the deformation properties of the natural as well as the stabilised clay can be modelled in a conventional way. Hence, the development is to give a realistic description of the interaction between these two parts of the soil. A notable feature of this is to describe the stress distribution in the soil in a simple, yet relevant way.
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| 9. |
- Bengtson, Per, et al.
(författare)
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Bacterial immobilization and remineralization of N at different growth rates and N concentrations
- 2005
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Ingår i: FEMS Microbiology Ecology. - : Oxford University Press (OUP). - 1574-6941 .- 0168-6496. ; 54:1, s. 13-19
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Tidskriftsartikel (refereegranskat)abstract
- An experiment was designed to resolve two largely unaddressed questions about the turnover of N in soils. One is the influence of microbial growth rate on mobilization and remineralization of cellular N. The other is to what extent heterotrophic immobilization of NO3- is controlled by the soil concentration of NH4+. Bacteria were extracted from a deciduous forest soil and inoculated into an aqueous medium. Various N pool dilution/enrichment experiments were carried out to: (1) calculate the gross N immobilization and remineralization rates; (2) investigate their dependence on NH4+ and NO3- concentrations; (3) establish the microbial preference for NH4+ and NO3- depending on the NH4+/NO3- concentration ratio. Remineralization of microbial N occurred mainly at high growth rates and NH4+ concentrations. There was a positive correlation between NH4+ immobilization and remineralization rates, and intracellular recycling of N seemed to be an efficient way for bacteria to withstand low inorganic N concentrations. Thus, extensive remineralization of microbial N is likely to occur only when environmental conditions promote high growth rates. The results support previous observations of high NO3- immobilization rates, especially at low NH4+ concentrations, but NO3- was also immobilized at high NH4 concentrations. The latter can be understood if part of the microbial community has a preference for NO3- over NH4+ (c) 2005 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.
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| 10. |
- Bengtson, Per, et al.
(författare)
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Rapid turnover of DOC in temperate forests accounts for increased CO2 production at elevated temperatures
- 2007
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 10:9, s. 783-790
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The evidence for the contribution of soil warming to changes in atmospheric CO2 concentrations and carbon stocks of temperate forest ecosystems is equivocal. Here, we use data from a beech/oak forest on concentrations and stable isotope ratios of dissolved organic carbon (DOC), phosphate buffer-extractable organic carbon, soil organic carbon (SOC), respiration and microbial gross assimilation of N to show that respired soil carbon originated from DOC. However, the respiration was not dependent on the DOC concentration but exceeded the daily DOC pool three to four times, suggesting that DOC was turned over several times per day. A mass flow model helped to calculate that a maximum of 40% of the daily DOC production was derived from SOC and to demonstrate that degradation of SOC is limiting respiration of DOC. The carbon flow model on SOC, DOC, microbial C mobilization/immobilization and respiration is linked by temperature-dependent microbial and enzyme activity to global warming effects Of CO2 emitted to the atmosphere.
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