Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2013
Authors
Marit Jørgensen Kirsten Tørresen M Dyrhaug I. Myrstad J. Svendsen T. Magnussen A. Førde A. DiTommasoAbstract
No abstract has been registered
Authors
Marit Jørgensen Kirsten Tørresen Marit Dyrhaug Ingrid Myrstad Jan Svendsen Tone Magnussen Anniken Førde A. DiTommasoAbstract
No abstract has been registered
Authors
Sveinn Are Hanssen Jan Ove Bustnes Lisbeth Schnug Sophie Bourgeon Trond Vidar Johnsen Manuel Ballesteros Christian Sonne Dorte Herzke Igor Eulaers Veerle Jaspers Adrian Covaci Marcel Eens Duncan John Halley Truls Borg Moum Rolf Anker Ims Kjell E ErikstadAbstract
Parasites are natural stressors that may have multiple negative effects on their host as they usurp energy and nutrients and may lead to costly immune responses that may cause oxidative stress. At early stages, animals may be more sensitive to infectious organisms because of their rapid growth and partly immature immune system. The objective of this study was to explore effects of parasites by treating chicks of two raptor species (northern goshawk Accipiter gentilis and white-tailed sea eagle Haliaeetus albicilla) against both endoparasites (internal parasites) and ectoparasites (external parasites). Nests were either treated against ectoparasites by spraying with pyrethrin or left unsprayed as control nests. Within each nest, chicks were randomly orally treated with either an antihelminthic medication (fenbendazole) or sterile water as control treatment. We investigated treatment effects on plasma (1) total antioxidant capacity TAC (an index of nonenzymatic circulating antioxidant defenses), (2) total oxidant status TOS (a measure of plasmatic oxidants), and (3) immunoglobulin levels (a measure of humoral immune function). Treatment against ectoparasites led to a reduction in circulating immunoglobulin plasma levels in male chicks. TOS was higher when not receiving any parasite reduction treatment and when receiving both endo- and ectoparasitic reduction treatment compared with receiving only one treatment. TAC was higher in all treatment groups, when compared to controls. Despite the relatively low sample size, this experimental study suggests complex but similar relationships between treatment groups and oxidative status and immunoglobulin levels in two raptor species. Costs of parasitism, immunoecology, immunoglobulin, oxidative status.
Abstract
No abstract has been registered
Abstract
The ground-based harvesting system consisting of a harvester and a forwarder is the dominant harvesting system in parts of the world, due to its high productivity. Both machines usually operate along extraction trails, and are equipped with cranes that can reach some distance from the extraction trail. In this work we optimize the layout of an extraction trail network by considering how terrain topography influences the cost of forwarding. Given the complexity of finding optimal machine trails for terrain transportation, traditional optimization methods might be limited due to the problem size. In this study, the optimization is done with a greedy constructive heuristic and a Greedy Randomized Adaptive Search Procedure (GRASP) metaheuristic, and the results of the two solution techniques are compared. Both the greedy heuristic and the GRASP metaheuristic were examined for a semi-random terrain and a smooth cone-shaped terrain, and provided useable extraction trail layouts in terms of how a forest machine operates on slopes. The objective value of the solution found by the GRASP metaheuristic was 5.6% better than the greedy heuristic in the semi-random terrain, and 2.3% better in the cone-shaped terrain. The result of this study showed that the GRASP metaheuristic is useful for finding feasible routes in the terrain, increasing efficiency. The method could be useful for planning feasible routes in the terrain, thereby increasing efficiency, or for acquiring a better estimate of the cost of terrain transport in price setting.
Abstract
No abstract has been registered
Authors
Bruce Talbot Morten NittebergAbstract
No abstract has been registered
Authors
Helge BerglannAbstract
This paper shows that a simple scheme of non-linear taxes coupled with tradable pollution permits can secure the .rst best outcome even in absence of information about abatement costs. Evidence of the existence of a Pareto optimal Nash equilibrium is given. Di¤erential system theory and stochastic approximation are used to prove that the outcome is globally and locally stable. Equilibrium is reached after repeated play. At each round agents make myopic steps and form local approximations, restricting their attention to one variable at any stage. The same procedure also applies also when stochastic elements are involved.
Authors
Siv SkarAbstract
No abstract has been registered
Authors
Theo RuissenAbstract
No abstract has been registered