| 11. |
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| 12. |
- Andrén, O., et al.
(författare)
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Barley straw decomposition with varied levels of microbial grazing by Folsomia fimetaria (L.) (Collembola, Isotomidae)
- 1985
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Ingår i: Oecologia. - : Springer-Verlag New York. - 0029-8549 .- 1432-1939. ; 68:1, s. 57-62
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Tidskriftsartikel (refereegranskat)abstract
- Folsomia fimetaria (L.) were added (0, 5, 10, 20 animals) to 0.100 g barley straw which had been inoculated 10 days (244 h) earlier with a natural soil microflora. Respiration (CO2 evolution) was monitored continuously. Mass loss, fungal standing crop (total and FDA-active), bacterial and protozoan biomass were estimated 42 days (1,000 h) after microbial inoculation. The degree of surface cover by hyphae was surveyed at regular intervals. No significant differences (P>0.05) were found in respiration, mass loss or microbial biomass, but the density of surface hyphae were reduced by addition of Collembola. Fungal production was low, less than 5% of the estimated microbial production, and could not account for all collembolan growth during incubation. F. fimetaria appeared to consume mainly bacteria and protozoa, and had little impact on carbon mineralization.
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| 13. |
- Angerbjörn, Anders
(författare)
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Mountain Hare Populations on Islands - Effects of Predation by Red Fox
- 1989
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Ingår i: Oecologia. - New York : Springer Verlag. - 0029-8549 .- 1432-1939. ; 81:3, s. 335-340
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Tidskriftsartikel (refereegranskat)abstract
- On islands off the west coast of Sweden the density of mountain hares (Lepus timidus L.) is very high. One of the main predators on hares, the red fox (Vulpes vulpes L.), is only present during short periods. Data on hare density and predation by red fox and eagle owl (Bubo bubo (L.)) has been analyzed from five islands over several years. Winter mortality in years with low predation pressure was independent of hare density. But when red fox or eagle owl were present on islands (i.e., high predation pressure) winter mortality became density dependent. Thus, at low density, winter mortality did not increase through red fox predation. But at densities up to two hares/ha, predation pressure was increasing and could be limiting for these populations. At still higher hare density predation pressure became less intensive. The functional response for foxes preying on hares showed a type II or a sigmoid type III response pattern. In normal summers, the population increase due to reproduction was at least two-fold. When a fox was present there was instead a sharp decrease in hare numbers. Fox predation had a stronger effect in summer than in winter. By switching between islands and mainland areas from winter to summer, a fox can stabilize fluctuations in hare numbers on the islands. This is dependent on how often the ice permits a fox to reach an island and the lack of numerical response by predators.
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| 14. |
- Anna, B., 1960-, et al.
(författare)
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Animal model of rotavirus infection in rabbits - protection obtained without shedding of viral antigen.
- 1989
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Ingår i: Archives of Virology. - : Springer. - 0304-8608 .- 1432-8798. ; 107:3-4, s. 237-251
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Tidskriftsartikel (refereegranskat)abstract
- A small animal model was developed in order to investigate the pathogenesis and immunology of rotavirus infections and to study the interaction of different virus strains. Seronegative rabbits of the breed French Lop were used. Two rabbit rotavirus strains, belonging to the same serotype, were used: 82/311 F and R-2, both isolated during diarrhoeal outbreaks in commercial rabbitries. The animals were inoculated orally. The viral shedding and the serological response was monitored by ELISA. Initially six weeks old kits were given four different doses of strain R-2. With doses ranging from 1 x 10(3) to 1 x 10(6) TCID50 all animals seroconverted, but for the lowest dose no viral excretion could be detected. No clinical symptoms were observed. Subsequently the age periods during which the animals were susceptible to the strain R-2 was investigated. The rabbits seroconverted and shed rotavirus antigen, independent of age of six or 22 weeks. None of the animals had diarrhoea. Administration of strain 82/311 F did not result in viral shedding, independently of dose, but all the animals seroconverted. It was also shown for the strain R-2 that when challenging with the same strain four weeks post inoculation that the animals were protected; no viral shedding was detected at the second infection. Strain 82/311 F gave protection against R-2 when the rabbits were challenged four weeks post inoculation.
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| 15. |
- Aronsson, Gunnar
(författare)
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Construction of singular solutions to the p-harmonic equation and its limit equation for p=∞
- 1986
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Ingår i: Manuscripta mathematica. - 0025-2611 .- 1432-1785. ; 56:2, s. 135-158
-
Tidskriftsartikel (refereegranskat)abstract
- Here, all solutions of the form u=rkf(φ) to the p-harmonic equation, div(|∇u|p-2∇u)=0, (p>2) in the plane are determined. One main result is a representation formula for such solutions. Further, solutions with an isolated singularity at the origin are constructed (Theorem 1). Graphical illustrations are given at the end of the paper. Finally, all solutions u=rkf(φ) of the limit equation for p=∞, ux2uxx+2uxuyuxy+uy2uyy=2, are constructed, some of which have a "strong" singularity at the origin (Theorem 2).
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| 16. |
- Aronsson, Gunnar
(författare)
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On certain singular solutions of the partial differential equation ux2uxx+2uxuyuxy+uy2uyy=0
- 1984
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Ingår i: Manuscripta mathematica. - 0025-2611 .- 1432-1785. ; 47:1-3, s. 133-151
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Tidskriftsartikel (refereegranskat)abstract
- The partial differential equation treated here is the formal limit of the p-harmonic equation in R2, for p →∞. Questions related to the smoothness of solutions and the possible existence of stationary points are central for the theory. The singular solutions constructed here bring new light on these questions.
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| 17. |
- Bendix, Tom, et al.
(författare)
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An evaluation of a tiltable office chair with respect to seat height, backrest position and task
- 1986
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Ingår i: European Journal of Applied Physiology and Occupational Physiology. - : Springer Science and Business Media LLC. - 0301-5548 .- 1432-1025 .- 1439-6327. ; 55:1, s. 30-36
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Tidskriftsartikel (refereegranskat)abstract
- The amount of spontaneous movement during seated office work was estimated by analysing the tilting movements of a tiltable office chair. Both movement frequency and amplitude range were considered. The seat inclinations and subjective acceptability were also recorded.The seat was moved more frequently and with a greater range when adjusted 6 cm above popliteal level compared to 1 cm below, or when the backrest was pushed anteriorly or posteriorly compared to a middle position. The greatest acceptability occurred with the highest seat adjustment and the backrest in the middle position. Typing or desk-work influenced movement to a similar extent.
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| 18. |
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| 19. |
- Bengner, Urban, et al.
(författare)
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Changes in incidence and prevalence of vertebral fractures during 30 years
- 1988
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Ingår i: Calcified Tissue International. - 1432-0827. ; 42:5, s. 293-296
-
Tidskriftsartikel (refereegranskat)abstract
- The age and sex-specific incidence and prevalence of vertebral compression fractures were compared between the 1950s and 1980s in an urban population. In women over 80 years of age the incidence of symptomatic vertebral fractures has increased approximately four times; in elderly men even more. Mainly, low-energy trauma has caused these fractures. Thus, one clinical manifestation of osteoporosis--vertebral fracture--has increased in number, incidence, and prevalence over the last 30 years.
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| 20. |
- Bengtsson, Hans, et al.
(författare)
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Parental feeding rate in relation to begging behavior in asynchronously hatched broods of the great tit Parus major: An experimental study.
- 1983
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Ingår i: Behavioral Ecology and Sociobiology. - 1432-0762. ; 12:3, s. 243-251
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Tidskriftsartikel (refereegranskat)abstract
- Four experiments manipulated the stimulus situation encountered by great tits on their feeding visits to the brood in order to explore its effect on feeding rate. Three broods containing 8, 8, and 10 nestlings were studied. A higher feeding rate was observed under the following conditions: (1) after a period of food deprivation, as compared with normal conditions and satiation through artifical feeding; (2) in periods when recorded begging calls were played during feeding visits, as compared with control periods; and (3) after temporary removal from the nest of heavier, as compared with lighter, siblings. The lighter nestlings benefitted more (in terms of weight gain) from the increase in parental feeding rate following the playing of begging calls than did the heavier nestlings. Differences in weight within broods did not affect the amount of food the parents brought. It is concluded that parental feeding rate is affected not simply by the begging of the hungriest nestling but rather by the behavior of all the nestlings, which makes possible an adjustment of the feeding rate to the average hunger level of the brood.
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