| 1. |
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| 2. |
- Lundberg, Angela, et al.
(författare)
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Ash on snow a tool : a tool to prevent flooding?
- 2001
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Ingår i: Nordic Hydrology. - : IWA Publishing. - 0029-1277 .- 1996-9694. ; 32:3, s. 195-214
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Tidskriftsartikel (refereegranskat)abstract
- Years with late spring in combination with thick snow-pack constitute risk for flooding. To decrease that risk, the possibility of spreading albedo-lowering material (wood ash) on parts of a basin snow has been examined. By blackening the snow more solar radiation is absorbed and the snowmelt is enhanced. If sun-exposed parts of the basin are ash-treated (before normal runoff starts) the runoff will be distributed over a longer period of time and the risk of flooding will be reduced. Wood ash in different concentrations was spread on small snow plots and melt rates and albedo were measured. For snow covered with 0.03 kg ash m super(-2), the albedo was decreased from approximately 0.60 for natural snow to approximately 0.25, resulting in approximately 90% more absorbed short-wave radiation. Melt on the ash treated surface, (daily average snow water equivalent), was 70% larger than melt on natural snow (12 and 7 mm d super(-1) respectively). A five times larger concentration (0.15 kg m super(-2)) only increased the melt rate to 14 mm d super(-1). The temperature-index method was shown to be inadequate for modelling the melt rate for the ash treated snow. A radiation-index model, based on absorbed incoming short wave radiation, was shown to model the melt rate better than the temperature-index method.
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| 3. |
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| 4. |
- Aldskogius, Håkan
(författare)
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Microglia in neuroregeneration
- 2001
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Ingår i: Microscopy research and technique (Print). - : Wiley. - 1059-910X .- 1097-0029. ; 54:1, s. 40-46
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Tidskriftsartikel (refereegranskat)abstract
- Microglia has the potential to produce and release a range of factors that directly and/or indirectly promote regeneration in the injured nervous system. The overwhelming evidence indicates, however, that this potential is generally not expressed in vivo. Activated microglia may enhance neuronal degeneration following axotomy, thereby counteracting functional recovery. Microglia does not seem to contribute significantly to axonal outgrowth after peripheral nerve injury, since this process proceeds uneventful even if perineuronal microglia is eliminated. The phagocytic phenotype of microglia is highly suppressed during Wallerian degeneration in the central nervous system. Therefore, microglia is incapable of rapid and efficient removal of myelin debris and its putative growth inhibitory components. In this way, microglia may contribute to regeneration failure in the central nervous system. Structural and temporal correlations are compatible with participation by perineuronal microglia in axotomy-induced shedding of presynaptic terminals, but direct evidence for such participation is lacking. Currently, the most promising case for a promoting effect on neural repair by activated microglia appears to be as a mediator of collateral sprouting, at least in certain brain areas. However, final proof for a critical role of microglia in these instances is still lacking. Results from in vitro studies demonstrate that microglia can develop a regeneration supportive phenotype. Altering the microglial involvement following neural injury from a typically passive or even counterproductive state and into a condition where these cells are actively supporting regeneration and plasticity is, therefore, an exciting challenge and probably a realistic goal.
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| 5. |
- Andersson, Ulrika, et al.
(författare)
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Svensk Straffrättskrönika 1991-2000
- 2001
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Ingår i: Nordisk tidsskrift for kriminalvidenskab. - 0029-1528. ; :1, s. 51-65
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Tidskriftsartikel (refereegranskat)
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| 6. |
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| 7. |
- Bechta, Sevostian, et al.
(författare)
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Experimental studies of oxidic molten corium-vessel steel interaction
- 2001
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Ingår i: Nuclear Engineering and Design. - 0029-5493 .- 1872-759X. ; 210:1-3, s. 193-224
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Tidskriftsartikel (refereegranskat)abstract
- The experimental results of molten corium-steel specimen interaction with molten corium on the 'Rasplav-2' test facility are presented. In the experiments, cooled vessel steel specimens positioned on the molten pool bottom and uncooled ones lowered into the molten pool were tested. Interaction processes were studied for different corium compositions, melt superheating and in alternative (inert and air) overlying atmosphere. Hypotheses were put forward explaining the observed phenomena and interaction mechanisms. The studies presented in the paper were aimed at the detection of different corium-steel interaction mechanisms. Therefore certain identified phenomena are more typical of the ex-vessel localization conditions than of the in-vessel corium retention. Primarily, this can be referred to the phenomena of low-temperature molten corium-vessel steel interaction in oxidizing atmosphere.
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| 8. |
- Berndtsson, R., et al.
(författare)
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Solar-climatic relationship and implications for hydrology
- 2001
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Ingår i: Nordic Hydrology. - 0029-1277. ; 32:2, s. 65-84
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Tidskriftsartikel (refereegranskat)abstract
- Research during the latest years has indicated a significant connection between climate and solar activity. Specifically, a relationship between Northern Hemisphere air temperature and sunspot cycle length (SCL) has been shown. By using monthly SCL and land air temperature from 1753-1990 (238 years) we show that this relationship also holds for a single observation point in south of Sweden. Using data after 1850 yields a statistically significant linear correlation of 0.54 between SCL and mean temperature. Furthermore, we show that there are indications of a low-dimensional chaotic component in both SCL and the interconnected mean land air temperature. This has important implications for hydrology and water resources applications. By pure definition of chaos this means that it is virtually impossible to make long-term predictions of mean temperature. Similarly, because of the strong connection between temperature and many hydrological components, it is probable that also long-term water balance constituents may follow chaotic trajectories. Long-term projections of water resources availability may therefore be impossible. Repeated short-term predictions may, however, still be viable. We exemplify this by showing a technique to predict interpolated mean temperature 6 and 12 months ahead in real time with encouraging results. Improving the technique further may be possible by including information on the SCL attractor. To summarize, research into the possible existence of chaotic components in hydrological processes should be an important task for the next years to come.
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| 9. |
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| 10. |
- Brodin, Gert, 1963-, et al.
(författare)
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Photon frequency conversion induced by gravitational radiation
- 2001
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Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 63
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Tidskriftsartikel (refereegranskat)abstract
- We consider the propagation of gravitational radiation in a magnetized multicomponent plasma. It is shown that large density perturbations can be generated, even for small deviations from flat space, provided the cyclotron frequency is much larger than the plasma frequency. Furthermore, the induced density gradients can generate frequency conversion of electromagnetic radiation, which may give rise to an indirect observational effect of the gravitational wave
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| 11. |
- Ekblad, Alf, 1957-, et al.
(författare)
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Natural abundance of C-13 in CO2 respired from forest soils reveals speed of link between tree photosynthesis and root respiration
- 2001
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Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 127:3, s. 305-308
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Tidskriftsartikel (refereegranskat)abstract
- Soil respiration from a boreal mixed coniferous forest showed large seasonal variation in natural abundance of 13C, ranging from –21.6‰ to –26.5‰. We tested if weather conditions could explain this variation in δ13C of respired CO2, and found that the air relative humidity 1–4 days before the days of CO2 sampling best explained the variation. This suggested that high δ13C values were caused by effects of air humidity on isotope fractionation during photosynthesis and that it took 1–4 days for the C from canopy photosynthesis of 20–25 m trees to become available for root/rhizosphere respiration. We calculated that these new photoassimilates could account for at least 65% of total soil respiration.
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| 12. |
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| 13. |
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| 14. |
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| 15. |
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| 16. |
- Jacobsson, Staffan, et al.
(författare)
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A Tomographic Method for Verification of the Integrity of Spent Nuclear Fuel Assemblies - I: Simulation Studies
- 2001
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Ingår i: Nuclear Technology. - 0029-5450. ; 135:2, s. 131-145
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Tidskriftsartikel (refereegranskat)abstract
- A tomographic method for experimental investigation of the integrity of used light water reactor fuel assemblies has been developed. It is based on spectroscopic measurements of the gamma radiation from fission products in fuel rods. The method utilizes beforehand information about the nominal geometry of both the measured fuel assembly and the measurement equipment. A reconstruction code of the algebraic type has been written. The potential of the technique has been examined in extensive simulations, assuming a gamma-ray energy of either 662 keV (137Cs) or 1274 keV (154Eu). The ability of detecting various configurations of manipulated rods, both single and in groups, has been investigated. Two main types of manipulations have been simulated. First, there is the removal of rods without replacement. The results indicate that all investigated configurations of removed rods in boiling water reactor (BWR) fuel can be reliably detected using 137Cs radiation. For pressurized water reactor (PWR) fuel, the same result is obtained, with the exception of the most central positions. Here, the more penetrating radiation from 154Eu may have to be used. Second, there is the replacement of rods with fresh fuel or fuel-like material. The results clearly indicate that all simulated cases of such manipulation can be most confidently detected. The simulations include various configurations of replaced rods in both BWR and PWR fuel, using both gamma-ray energies.
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| 17. |
- Jacobsson, Staffan, et al.
(författare)
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A Tomographic Method for Verification of the Integrity of Spent Nuclear Fuel Assemblies - II: Experimental Investigation
- 2001
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Ingår i: Nuclear Technology. - 0029-5450 .- 1943-7471. ; 135:2, s. 146-153
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Tidskriftsartikel (refereegranskat)abstract
- A tomographic method for verification of the integrity of used light water reactor fuel has been experimentally investigated. The method utilizes emitted gamma rays from fission products in the fuel rods. The radiation field is recorded in a large number of positions relative to the assembly, whereby the source distribution is reconstructed using a special-purpose reconstruction code.An 8 × 8 boiling water reactor fuel assembly has been measured at the Swedish interim storage (CLAB), using installed gamma-scanning equipment modified for the purpose of tomography. The equipment allows the mapping of the radiation field around a fuel assembly with the aid of a germanium detector fitted with a collimator with a vertical slit. Two gamma-ray energies were recorded: 662 keV (137Cs) and 1274 keV (154Eu). The intensities measured in 2520 detector positions were used as input for the tomographic reconstruction code. The results agreed very well with simulations and significantly revealed a position containing a water channel in the central part of the assembly.
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| 18. |
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| 19. |
- Kellner, Erik, et al.
(författare)
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Calibration of time domain reflectometry for water content in peat soil
- 2001
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Ingår i: Nordic Hydrology. - 0029-1277 .- 1996-9694. ; 32:4-5, s. 315-332
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Tidskriftsartikel (refereegranskat)abstract
- Since peat soil differs from mineral soil in several respects, mineral-soil calibration functions for time domain reflectometry (TDR) are not necessarily applicable. This paper evaluates a number of calibration functions, both empirical polynomial and theoretical mixing models, on the basis of laboratory measurements on undisturbed Sphagnum peat samples. Deviations between different samples within this study indicate dissimilarities in dielectric properties between peats with different degrees of humification. Connections to physical properties such as amount of bound water and structural orientation are likely to exist. There is, however, a lack of methods to measure and quantify parameters expressing these properties. Therefore, until further studies on physical properties are accomplished, empirical or semi-empirical calibration curves are preferred. The best fit was obtained by an empirical, third order polynomial model. This model also gave a better fit than the mixing models when data were grouped into humification classes. However, all models reproduced pooled data with an r(2) better than 0.93.
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| 20. |
- Kimber, B, et al.
(författare)
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Primary prevention of psychological ill-helath among children and adolescents through social emotional learning in school.
- 2001
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Ingår i: Nordisk Psykologi. - 0029-1463. ; 53:3, s. 256-261
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the project is to test the extent to which systematic long-term work on social emotional learning (SEL) in school can reduce psychological ill-health and maladaptation (violence, bullying, truancy, problems with other pupils, etc,). The SEL program encompasses structured exercises for pupils so as to train self-awareness, empathy, the handling of emotions, motivation, and social competence. The project is being run for three school years at two compulsory schools in Botkyrka Municipality in Stockholm (pupils aged 6 to 16). The program also includes the training and supervision of teachers and other personnel, and the provision of information and motivation to parents. A baseline measurement was taken during the school year before the program was embarked upon. Thereafter annual measurements are taken through pupil self-reports and the reports of teachers and school administrators. Further, 30 randomly selected pupils are investigated in-depth through special personal interviews and interviews with parents and teachers. Classes in two other schools in Botkyrka that are entirely outside the program function as comparison groups.
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| 21. |
- Komarek, J, et al.
(författare)
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Some chroococcalean and oscillatorialean Cyanoprokaryotes from southern African lakes, ponds and pools
- 2001
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Ingår i: Nova Hedwigia: Zeitschrift für Kryptogamenkunde. - 0029-5035. ; 73:1-2, s. 129-160
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Tidskriftsartikel (refereegranskat)abstract
- This article is the first part (Chroococcales and Oscillatoriales) of a study of little known planktic and metaphytic cyanoprokaryotes (cyanophytes, cyanobacteria) from ponds, lakes and water reservoirs in southern Africa. Thirty-three species were observed, of which 24 are presented with comments. Ten new species are defined, and one species, originally described as a taxonomic form, is recombined to the specific level. Our results demonstrate the specificity of southern African cyanobacterial microflora.
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| 22. |
- Lankinen, Åsa
(författare)
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In vitro pollen competitive ability in Viola tricolor: temperature and pollen donor effects
- 2001
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Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 1432-1939 .- 0029-8549. ; 128:4, s. 492-498
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Tidskriftsartikel (refereegranskat)abstract
- In this study on Viola tricolor pollen, the competitive ability of 16 pollen donors originating from a wild population was analysed in a set of greenhouse and germination temperatures. The aim was to examine the consistency in donor pollen performance across temperatures and to see whether variation in performance was random or due to individual differences in the plastic response to temperature. Pollen tube growth rate in vitro was investigated in two greenhouse temperatures (on the day pollen was collected) and in four germination temperatures. In addition, pollen tube growth rate was assessed in vivo (in one temperature) to examine the relationship between in vivo and in vitro growth. A temperature difference of 5 K - corresponding to natural variation in time and space detected in the field - affected pollen tube growth rate. For both temperature components, significant pollen donor by temperature interactions were found and rank order of pollen donors changed across treatments. Although pollen competitive ability in violets was strongly influenced by both temperature components, the occurrence of pollen donor by temperature interactions indicates that donor siring ability varies with temperature. This, in turn, may suggest a means to maintain pollen competitive ability despite selection for this trait.
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| 23. |
- Liu, J. S., et al.
(författare)
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Effect of water radiolysis caused by dispersed radionuclides on oxidative dissolution of spent fuel in a final repository
- 2001
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Ingår i: Nuclear Technology. - 0029-5450 .- 1943-7471. ; 135:2, s. 154-161
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Tidskriftsartikel (refereegranskat)abstract
- When released out of a canister, the radionuclides originally incorporated in the spent fuel can still deposit radiation energy (even more efficiently) into the pore water, cause water radiolysis, and produce oxidants in the buffering material. This phenomenon is termed secondary water radiolysis. The oxidants thus produced can possibly diffuse back to oxidize the spent fuel and to increase the oxidative dissolution rare of the fuel, The effect of the secondary water radiolysis has been identified and preliminarily addressed by a mass-balance model. To explore whether the effect is significant on spent-fuel dissolution, the upper-boundary limit of the effect has been set up by considering a scenario that is very unlikely to occur. Several extreme assumptions have been made: First, the canister fails completely 10(3) yr after deposition; second, the sl,ent fuel is oxidized instantaneously; and third, the radionuclides considered are those that dominantly contribute to radiolysis between 10(3) to 10(5) yr. With these assumptions, the spent-fuel dissolution rate can be increased dramatically if 10% or more of the oxidants produced by the secondary water radiolysis diffuse back to oxidize the spent fuel. It thus indicates that the effect of the secondary water radiolysis could be significant with some extreme assumptions. With more realistic assumptions, the effect could possibly become minimal. The subject is worth further investigation.
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| 24. |
- Liu, Longcheng, et al.
(författare)
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A coupled model for oxidative dissolution of spent fuel and transport of radionuclides from an initially defective canister
- 2001
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Ingår i: Nuclear Technology. - 0029-5450 .- 1943-7471. ; 135, s. 273-285
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Tidskriftsartikel (refereegranskat)abstract
- An earlier model for oxidative dissolution of spent fuel was developed by including the release behavior of actinides from the fuel surface and the barrier effect of Zircaloy claddings. The aim here is to explore the possibility and consequences of precipitation in the water film around the fuel pellets due to solubility, and transport limitations of nuclides. The model has been applied in the performance assessment of a damaged canister under natural repository conditions, by coupling to a redox-front-based model for transport of nuclides. The simulation results identify? that the time of penetration of the canister, the size of the damage, and the initial free volume of the fuel rods are important factors that dominate the dissolution behavior of the fuel matrix and thus the transport behavior of actinides in the nearfield of a repository.
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| 25. |
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| 26. |
- Nilsson, Jan-Åke, et al.
(författare)
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The resting metabolic cost of egg laying and nestling feeding in great tits
- 2001
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Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 1432-1939 .- 0029-8549. ; 128:2, s. 187-192
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Tidskriftsartikel (refereegranskat)abstract
- To estimate the metabolic costs of regrowth of reproductive organs and formation of eggs, we compared the resting metabolic rate (RMR) of female great tits (Parus major) during the periods of ovarian recrudescence, egg laying, nestling feeding and during winter. We found RMR of individual females, as measured in an open circuit respirometer during night, to be significantly higher during all the breeding phases when compared to measurements during the winter. Females had a 12% increase in RMR during the nest-building phase, an increase of 27% during egg production and an increase of 20% during the chick feeding phase compared to RMR during winter. However, we found no significant difference in energy expenditure during the night between females producing eggs and females feeding chicks. A causal link between RMR and egg production was further confirmed by females producing large eggs having a higher RMR than females producing small eggs. Mass-specific RMR increased steadily from the winter throughout the breeding season, being highest when females were feeding their nestlings. Thus, even though females did not produce ovary-oviduct tissue or eggs during chick feeding, they had a very high RMR. We conclude that the biosynthetic cost of egg formation will probably not limit clutch size but may well, together with the cost of ovary-oviduct recrudescence, influence the timing of reproduction. We suggest that the high RMR of females feeding nestlings, probably is due to an increase in size and efficiency of the alimentary tract, needed to sustain a high rate of energy turnover during this period.
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| 27. |
- Norrman, L, et al.
(författare)
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The importance of the father to the social situation and self-image of the child.
- 2001
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Ingår i: Nordisk Psykologi. - 0029-1463. ; 53:4, s. 289-301
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of the current study was to explore the importance of the father to children's social situation and self image. 102 buys and girls, aged 9-11 years, who were either living with both parents or who had limited contact with the father, were assessed by way of a questionnaire, and through their drawings of their own families. Two questions and the drawings were designed to measure the children's perception of the father's importance and their relationhip to the father. The remaining questions covered the children's social situation among friends and their self image. More children with limited contact than children living with both parents indicated that the father was the most significant male person. Living arrangements also affected the buys' social situation, Only half of those with limited father contact felt that they were well liked by their peers. Girls exhibited a more favorable self image and were rated as having a more secure relationship to their father than did boys, both in intact and in split families. The results support previous research e.g. from Great Britain (Owuso-Bempah & Howitt).
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| 28. |
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| 29. |
- Olsson, Ola, et al.
(författare)
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Variability of patch type preferences in relation to resource availability and breeding success in a bird
- 2001
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Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 1432-1939 .- 0029-8549. ; 127:3, s. 435-443
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates how variability in partial foraging preferences for patch types can be used as a behavioral indicator of the energetic value of that patch type, and of overall food availability in the territory. The species studied was the lesser spotted woodpecker (Dendrocopos minor) and the patch types it uses are four groups of tree species (oak Quercus robur, birch Betula pendula, B. pubescens, alder Alnus glutinosa, and lime Tilia cordata), in which it feeds upon wood-living insect larvae. We partition the variation in foraging preferences into three scales. Firstly, within territories, the foraging preference for a tree species group was positively related to the prey density in that species group. That is, the preferences measure the patch types' energetic profit-abilities. This result should be general in cases like the present, where the costs of using different alternatives do not differ substantially. It may therefore be the preferred behavioral indicator in determining the relative benefits associated with different alternatives. Secondly, between the seven years of study, much of the variation in tree species group preferences was attributable to measured fluctuations in the density of one important prey species (Argyresthia goedarthella, Argyresthidae, Lepidoptera), which occurred in some years on birch, in others on alder, and in one year was virtually absent. Thus, in concordance with the previous result, the values of these tree species groups fluctuated between years according to prey density. Thirdly, between territories, we found that the preference for one tree species, lime, was higher in areas where it was more abundant. We attribute this to the fact that the density (per patch) of at least one important prey species (Stenostola dubia, Cerambycidae, Coleoptera) on lime increased with the abundance of its host tree species in the territory. That is, the overall food availability was higher in territories where lime was more common. Hence, the preference for lime estimates overall food availability. This conclusion is strengthened by two additional facts: the preference for lime correlates positively (1) with the average giving-up density of food, which has previously been shown to estimate overall food availability in the territories, and (2) with reproductive success, at least during the early stages of reproduction.
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| 30. |
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| 31. |
- Persson, Magnus
(författare)
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Solute transport measurements in different soil types using time domain reflectometry
- 2001
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Ingår i: Nordic Hydrology. - 0029-1277. ; 32:2, s. 99-114
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Tidskriftsartikel (refereegranskat)abstract
- During recent years, time domain reflectometry (TDR) has proved to be a valuable tool for both water content (theta) and bulk electrical conductivity (sigma (a)) measurements. To allow resident solute concentration (C-r) measurements, a calibration procedure is necessary for the relationship between sigma (a) and C-r. Two main calibration approaches exist. Direct calibration allows for C-r measurements with varying theta, while the indirect calibration method is used for conditions with constant theta. In this paper, three methods of achieving direct calibration parameters are presented and evaluated in three different soil types. Calibrations are made in both disturbed and undisturbed soil columns as well as in the field. It was shown that there were only small differences between calibration methods in homogeneous sand. In other soils, choosing the correct calibration is important. In clay soils, solute transport measurements are difficult to take under conditions with varying theta, therefore it is suggested that only the indirect calibration approach should be used. When using TDR it is important to be aware of the accuracy of the TDR system in order to interpret data correctly. Some error sources are thus also briefly discussed.
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| 32. |
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| 33. |
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| 34. |
- Rutgersson, Anna, et al.
(författare)
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Precipitation Estimates over the Baltic Sea: Present State of the Art
- 2001
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Ingår i: Nordic Hydrology. - 0029-1277 .- 1996-9694. ; 32:4, s. 285-314
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Tidskriftsartikel (refereegranskat)abstract
- Precipitation is one of the main components in the water balance, and probably the component determined with the greatest uncertainties. In the present paper we focus on precipitation (mainly rain) over the Baltic Sea as a part of the BALTEX project to examine the present state of the art concerning different precipitation estimates over that area. Several methods are used, with the focus on 1) interpolation of available synoptic stations; 2) a mesoscale analysis system including synoptic, automatic, and climate stations, as well as weather radar and an atmospheric model; and 3) measurements performed on ships. The investigated time scales are monthly and yearly and also some long-term considerations are discussed. The comparison shows that the differences between most of the estimates, when averaged over an extended period and a larger area, are in the order of 10-20%, which is in the same range as the correction of the synoptic gauge measurements due to wind and evaporation losses. In all data sets using gauge data it is important to include corrections for high winds. To improve the structure of precipitation over sea more focus is to be put on the use of radar data and combinations of radar data and other data. Interpolation methods that do not consider orographic effects must treat areas with large horizontal precipitation gradients with care. Due to the large variability in precipitation in time and space, it is important to use long time periods for climate estimates of precipitation Ship measurements are a valuable contribution to precipitation information over sea, especially for seasonal and annual time scales.
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| 35. |
- Servin, Martin, et al.
(författare)
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Cyclotron damping and Faraday rotation of gravitational waves
- 2001
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Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 64
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Tidskriftsartikel (refereegranskat)abstract
- We study the propagation of gravitational waves in a collisionless plasma with an external magnetic field parallel to the direction of propagation. Because of resonant interaction with the plasma particles the gravitational wave experiences cyclotron damping or growth, the latter case being possible if the distribution function for any of the particle species deviates from thermodynamical equilibrium. Furthermore, we examine how the damping and dispersion depends on temperature and on the ratio between the cyclotron and gravitational wave frequency. The presence of the magnetic field leads to different dispersion relations for different polarizations, which in turn imply Faraday rotation of gravitational waves.
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| 36. |
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| 37. |
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| 38. |
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| 39. |
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| 40. |
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| 41. |
- von Euler, F, et al.
(författare)
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Taxonomic distinctness and species richness as measures of functional structure in bird assemblages
- 2001
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Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 1432-1939 .- 0029-8549. ; 129:2, s. 304-311
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Tidskriftsartikel (refereegranskat)abstract
- Most traditional "biodiversity" indices have an uncertain ecological interpretation, unfavourable sampling properties, and excessive data requirements. A new index of taxonomic distinctness (the average evolutionary distance between species in an assemblage) has many advantages over traditional measures, but its ecological interpretation remains unclear. We used published behavioural species data in conjunction with bird atlas data to quantify simple functional metrics (the fraction of species engaged in non-competitive interactions, and the average between-species disparity in habitat preferences) for breeding-bird assemblages in Europe and North America. We then analysed correlations of functional metrics with taxonomic distinctness and species richness, respectively. All functional metrics had weak, positive correlations with species richness. In contrast, correlations between functional metrics and taxonomic distinctness ranged from slightly negative to strongly positive, depending on the relative habitat heterogeneity, and on the resource involved in the between-species interaction. Strong positive correlations between taxonomic distinctness and the fraction of interactive species occurred for resources with few producer species per consumer species, and we suggest that taxonomic distinctness is consistently correlated with conservation worth. With its favourable sampling properties and data requirements, this taxonomic distinctness measure is a promising tool for biodiversity research and for environmental monitoring and management.
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| 42. |
- Wadsby, Marie, et al.
(författare)
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From pregnancy to parenthood : A study of couples' relationship.
- 2001
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Ingår i: Nordisk Psykologi. - 0029-1463. ; 53:4, s. 275-288
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Tidskriftsartikel (refereegranskat)abstract
- The relationship between 60 first time parents-to-be were studied during pregnancy and when the child was 1 year old in order to find out if, and then in what way the relationship changes during transition to parenthood. Although the relationship was rated as highly harmonious by both women and men during the pregnancy, a significant decline in marital satisfaction was noted when the child was 1 year old. The men experienced an impairment what concerned financial matters, leisure activities, and relations to family and friends. Both women and men experienced an impairment what concerned closeness and sexuality, and a change in opinion about children and parenthood. The women scored, in opposite to the men, higher on conception of life at both study occasions, although they scored lower at the follow-up, The lowest agreement among the couples concerned leisure activities, and it was in this area together with opinion about children and parenthood and conception of life that the agreement had decreased most at the second study occasion.The family climate had changed in direction towards an increased experience of distance according to both women and men, and the men also experienced a decrease in closeness, If the decision to have a baby not had been a joint decision, or if one of the spouses ealier had thought of a separation, there was a lower marital satisfaction at both study occasions.
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| 43. |
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| 44. |
- Wallenius, Janne, 1968-, et al.
(författare)
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Application of burnable absorbers in an accelerator-driven system
- 2001
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Ingår i: Nuclear science and engineering. - 0029-5639 .- 1943-748X. ; 137:1, s. 96-106
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Tidskriftsartikel (refereegranskat)abstract
- The application of burnable absorbers (BAs) to minimize power peaking, reactivity loss, and capture-to-fission probabilities in an accelerator-driven waste transmutation system has been investigated. Boron-IO-enriched B4C absorber rods were introduced into a lead-bismuth-cooled core fueled with transuranic (TRU) discharges from light water reactors to achieve the smallest possible power peakings at beginning-of-life (BOL) subcriticality level of 0.97 Detailed Monte Carlo simulations show that a radial power peaking equal to 1.2 at BOL is attainable using a four-zone differentiation in BA content. Using a newly written Monte Carlo burnup code, reactivity losses were calculated to be 640 pcm per percent TRU burnup for unrecycled TRU discharges. Comparing to corresponding values in BA-free cores, BA introduction diminishes reactivity losses in TRU-fueled subcritical cores by similar to 20%. Radial power peaking after 300 days of operation at 1200-MW thermal power was0.92, which appears to be acceptable, with respect to limitations in cladding and fuel temperatures. In addition, the else of BAs yields significantly higher fission-to-capture probabilities in even-neutron-number nuclides. Fission-to-absorption probability ratio for Am-241 equal to 0.33 was achieved in the configuration studied. Hence, production of the strong alpha-emitter Cm-242 is reduced, leading to smaller fuel-swelling rates and pin pressurization. Disadvantages following BA introduction such as increase of void worth and decrease of Doppler feedback in conjunction with small values of beta (eff), need to be addressed by derailed studies of subcritical core dynamics.
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| 45. |
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| 46. |
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| 47. |
- Wihlbäck, A C, et al.
(författare)
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Influence of postmenopausal hormone replacement therapy on platelet serotonin uptake site and serotonin 2A receptor binding.
- 2001
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Ingår i: Obstetrics and Gynecology. - 0029-7844 .- 1873-233X. ; 98:3, s. 450-7
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To examine whether binding of [3H]paroxetine to the platelet serotonin transporter or binding of [3H]lysergic acid diethylamide (LSD) to the platelet 5-HT(2A) receptor are influenced by postmenopausal estrogen/progestogen treatment. METHODS: Twenty-three postmenopausal women with climacteric symptoms completed this double-blind, randomized, crossover study. The women received 2 mg of estradiol continuously during four 28-day cycles. In the last 14 days of each cycle, 10 mg of medroxyprogesterone acetate, 1 mg of norethindrone acetate, or placebo was given. Before treatment, as well as once during the last week of each treatment, blood samples were collected for analysis of [3H]LSD and [3H]paroxetine binding. The power of the study setup was 81%. The study had an effect size of 0.36, corresponding to the ability to detect a 15% difference in [3H]paroxetine and [3H]LSD binding between treatments with alpha =.05 and beta =.20, based on a previously reported standard deviation within cells of 20% of the mean binding values. RESULTS: The number of platelet receptors (B(max)), or the affinity of the radioligand to the receptor (K(d)), for [3H]paroxetine binding did not change during estrogen or estrogen-progestogen treatment, nor did B(max) or K(d) for [3H]LSD binding change during the different treatments. However, in a subgroup of depressed patients, the decrease in B(max) for [3H]LSD binding during treatment was significantly more pronounced than in the nondepressed subgroup (P <.05). CONCLUSION: Estrogen treatment with or without the addition of progestogen does not affect binding to the serotonin transporter or to the serotonergic 5-HT(2A) receptor in healthy postmenopausal women.
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| 48. |
- Windecker, G., et al.
(författare)
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Phase distribution in a BWR fuel assembly and evaluation of a multidimensional multifield model
- 2001
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Ingår i: Nuclear Technology. - 0029-5450 .- 1943-7471. ; 134:1, s. 49-61
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Tidskriftsartikel (refereegranskat)abstract
- The phase and mass flux distribution is analyzed in the fuel bundle of a boiling water reactor (BWR). The numerical predictions of phase distribution, obtained with the multifield two-phase flow model implemented in a computational fluid dynamics code, are compared with detailed void measurements. The present model takes into account the detailed geometry of the assembly and the spatial distribution of heat sources. The influence of spacers is modeled by introducing pressure loss and turbulence sources in the momentum and turbulence equations, respectively. The model has been applied for simulation of bubbly two-phase flow for both subcooled and saturated nucleate boiling in a seven-rod bundle and a typical BWR fuel assembly. The predictions are in good agreement with tomographic measurements performed in the FRIGG loop at Westinghouse Atom.
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| 49. |
- Yang, Z. L., et al.
(författare)
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Numerical investigation of boiling regime transition mechanism by a Lattice-Boltzmann model
- 2001
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Ingår i: Nuclear Engineering and Design. - 0029-5493 .- 1872-759X. ; 204:1-3, s. 143-153
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Tidskriftsartikel (refereegranskat)abstract
- A numerical study has been performed to investigate the hydrodynamic aspects of the pool boilingon horizontal-, vertical- and downward-facing surfaces. The FlowLab code, which is based on a Lattice-Boltzmann (LB) model of two-phase flows, is employed. Macroscopic properties, such as surface tension (a) and contact angle (beta), are implemented through the fluid-fluid (G(sigma)) and fluid-solid (G(t)) interaction potentials. The model is found to express a linear relation between the macroscopic properties (sigma, beta) and microscopic parameters (G(sigma), G(t)). The simulation results on bubble departure diameter appear to have the same parametric dependence as the empirical correlation. Hydrodynamic aspects of two-phase flow regime transition mechanism are investigated for different surface-coolant configurations. Results of the LB simulation clearly demonstrate that not only the bubble nucleation site density (related, e.g. to the heater surface condition and heat fluxes), but also the surface position have a profound effect on the flow regime (pool boiling) characteristics. The results of the LB simulation of hydrodynamics of two-phase flow on the horizontal surface provide the pictures quite similar to the experimental observation for saturated pool boiling. Two mechanisms of flow (boiling) regime transition on the vertical surface are predicted for the local bubble coalescence at bubble generation site and the downstream bubble coalescence. On the downward-facing surfaces, friction between bubbles and the surface wall is found to significantly enlarge the bubble size prior the bubble slip upwards. This behavior is responsible for the earlier bubble coalescence, and therefore, lowers the maximum heat removal rate, in a similar regime of nucleate boiling on a downward-facing surface.
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| 50. |
- Åkerström, Malin
(författare)
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Recension av Hedda Giertsens avhandling
- 2001
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Ingår i: Nordisk tidsskrift for kriminalvidenskab. - 0029-1528. ; 2001:4, s. 350-350
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Recension (övrigt vetenskapligt/konstnärligt)
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