Sökning: "Eurasia"

Visar resultat 21 - 25 av 46 avhandlingar innehållade ordet Eurasia.

  1. 21. On the interaction between ice sheets and the large-scale atmospheric circulation over the last glacial cycle

    Författare :Marcus Löfverström; Rodrigo Caballero; Johan Nilsson; David Battisti; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Atmospheric stationary waves; coupled atmosphere-ice sheet modelling; stationary wave-ice sheet interactions; atmosfärvetenskap och oceanografi; Atmospheric Sciences and Oceanography;

    Sammanfattning : The last glacial cycle (c. 115-12 kyr BP) was the most recent in a series of recurring glaciations of the subpolar continents. Massive ice sheets evolved in Eurasia and North America, which, at their maximum, were of continental scale and together lowered the global sea-level by approximately 100 m. LÄS MER

  3. 22. Anthropogenic impact on predator guilds and ecosystem processes : Apex predator extinctions, land use and climate change

    Författare :Marianne Pasanen Mortensen; Bodil Elmhagen; Francisco Palomares; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Mesopredators; apex predators; top-down; bottom-up; interspecific killing; red fox; Eurasian lynx; grey wolf; wolverine; productivity; winter severity; cropland; zoologisk ekologi; Animal Ecology;

    Sammanfattning : Humans affect ecosystems by changing species compositions, landscape and climate. This thesis aims to increase our understanding of anthropogenic effects on mesopredator abundance due to changes in apex predator status, landscape and climate. LÄS MER

  4. 23. Assessing Holocene and late Pleistocene geomagnetic dipole field variability

    Författare :Andreas Nilsson; Kvartärgeologi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Geomagnetic field; palaeomagnetism; the Holocene; dipole tilt; dipole moment; cosmogenic radionuclides;

    Sammanfattning : Palaeomagnetic studies of continuous geological archives and archaeological artefacts are required to reconstruct geomagnetic field changes beyond the range of historical observations. In this thesis I assess the reliability of sedimentary palaeomagnetic data and Holocene dipole field reconstructions. LÄS MER

  5. 24. Genome evolution and adaptation of a successful allopolyploid, Capsella bursa-pastoris

    Författare :Dmytro Kryvokhyzha; Martin Lascoux; Vincent Castric; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; allopolyploidy; population structure; selection; genetic drift; gene expression; parental legacy; genetic load; Biologi med inriktning mot evolutionär funktionsgenomik; Biology with specialization in Evolutionary Functional Genomics;

    Sammanfattning : The term allopolyploid refers to an organism that originated through hybridization and increased its ploidy level by retaining the unreduced genomes of its parents. Both hybridization and polyploidy usually have negative consequences for the organism. LÄS MER

  7. 25. Nitrate stable isotopes and major ions in snow and ice from Svalbard

    Författare :Carmen Paulina Vega Riquelme; V. A. Pohjola; R. Pettersson; E. Isaksson; C. E. Bøggild; Kumiko Goto-Azuma; Uppsala universitet; []
    Nyckelord :nitrate stable isotopes; nitrate; NOx proxies; ice cores; percolation; ion relocation; Svalbard; stabila isotoper av nitrat; nitrat; indikator för kväveoxider; iskärnor; perkolation; joniska omlokalisering; Svalbard; Earth Science with specialization in Physical Geography; Geovetenskap med inriktning mot naturgeografi;

    Sammanfattning : Increasing atmospheric reactive nitrogen (Nr), as consequence of human activities, has generated accumulation of nitrate (NO3-) in Arctic regions. The Arctic has fragile nitrogen limited ecosystems that can be altered by increases of dry or wet deposition of Nr. LÄS MER