4 resultados para Islands of the Adriatic

em Doria (National Library of Finland DSpace Services) - National Library of Finland, Finland


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Att ett geografiskt territorium uppnår autonomi förklaras ofta av skillnad I etnicitet, språk eller religion. En region som skiljer sig i någon av dessa kulturella aspekter från övriga regioner i ett land anses därför ha större sannolikhet att utveckla autonomi. Pär M. Olausson visar i sin avhandling att kulturella aspekter inte är den viktigaste förklaringen till att vissa öar utvecklar autonomi. Kulturella aspekter är bara en del i förklaringen till varför vissa öar utvecklar autonomi medan andra förblir en integrerad del av moderlandet. Kulturella aspekter måste kombineras med andra aspekter för att utgöra en tillräcklig förklaring till skillnaden i autonomi. Bland de autonoma regionerna i världen idag utgör öar en klar majoritet. Öar anses ofta ha speciella egenskaper som gör att de skiljer sig från fastlandet. Känslan av samhörighet och gemenskap är ofta starkare på öar pga deras ofta isolerade läge vilket i sin tur anses förklara varför många öar utvecklar autonomi. Genom att studera både autonoma och icke-autonoma öar visar Olausson att autonomi kan förklaras av att ön ligger längre än 1 000 km från fastlandet eller att den skiljer sig från fastlandet i någon av de kulturella aspekterna, att den har varit ockuperad av främmande stat och därmed avskiljd från övriga landet eller utgjort en egen stat. Den viktigaste förklaringen till varför vissa öar utvecklar autonomi men inte andra är emellertid öns strategiska betydelse.

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Kartta kuuluu A. E. Nordenskiöldin kokoelmaan

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The application of VSC-HVDC technology throughout the world has turned out to be an efficient solution regarding a large share of wind power in different power systems. This technology enhances the overall reliability of the grid by utilization of the active and reactive power control schemes which allows to maintain frequency and voltage on busbars of the end-consumers at the required level stated by the network operator. This master’s thesis is focused on the existing and planned wind farms as well as electric power system of the Åland Islands. The goal is to analyze the wind conditions of the islands and appropriately predict a possible production of the existing and planned wind farms with a help of WAsP software program. Further, to investigate the influence of increased wind power it is necessary to develop a simulation model of the electric grid and VSC-HVDC system in PSCAD and examine grid response to different wind power production cases with respect to the grid code requirements and ensure the stability of the power system.

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The distribution and traits of fish are of interest both ecologically and socio-economically. In this thesis, phenotypic and structural variation in fish populations and assemblages was studied on multiple spatial and temporal scales in shallow coastal areas in the archipelago of the northern Baltic Proper. In Lumparn basin in Åland Islands, the fish assemblage displayed significant seasonal variation in depth zone distribution. The results indicate that investigating both spatial and temporal variation in small scale is crucial for understanding patterns in fish distribution and community structure in large scale. The local population of Eurasian perch Perca fluviatilis L displayed habitat-specific morphological and dietary variation. Perch in the pelagic zone were on average deeper in their body shape than the littoral ones and fed on fish and benthic invertebrates. The results differ from previous studies conducted in freshwater habitats, where the pelagic perch typically are streamlined in body shape and zooplanktivorous. Stable isotopes of carbon and nitrogen differed between perch with different stomach contents, suggesting differentiation of individual diet preferences. In the study areas Lumparn and Ivarskärsfjärden in Åland Islands and Galtfjärden in Swedish east coast, the development in fish assemblages during the 2000’s indicated a general shift towards higher abundances of small-bodied lower-order consumers, especially cyprinids. For European pikeperch Sander lucioperca L., recent declines in adult fish abundances and high mortalities (Z = 1.06–1.16) were observed, which suggests unsustainably high fishing pressure on pikeperch. Based on the results it can be hypothesized that fishing has reduced the abundances of large predatory fish, which together with bottom-up forcing by eutrophication has allowed the lower-order consumer species to increase in abundances. This thesis contributes to the scientific understanding of aquatic ecosystems with new descriptions on morphological and dietary adaptations in perch in brackish water, and on the seasonal variation in small-scale spatial fish distribution. The results also demonstrate anthropogenic effects on coastal fish communities and underline the urgency of further reducing nutrient inputs and regulating fisheries in the Baltic Sea region.