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Visar resultat 11 - 15 av 248 avhandlingar innehållade ordet dating.

  1. 11. The Origin of the Genus Flavivirus and the Ecology of Tick-Borne Pathogens

    Författare :John H.-O. Pettersson; Thomas Jaenson; Sven Bergström; Kenneth Nilsson; Mikael Thollesson; Per-Eric Lindgren; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Flavivirus; Virus dating; Molecular dating; Biogeography; Ixodes ricinus; Minimum infection rate; TBE; Tick-borne encephalitis virus; Rickettsia helvetica; Anaplasma phagocytophilum; Infection prevalence; RT-PCR; Biology with specialization in Systematics; Biologi med inriktning mot systematik;

    Sammanfattning : The present thesis examines questions related to the temporal origin of the Flavivirus genus and the ecology of tick-borne pathogens. In the first study, we date the origin and divergence time of the Flavivirus genus. It has been argued that the first flaviviruses originated after the last glacial maximum. LÄS MER

  3. 12. Tracing History : Phylogenetic, Taxonomic, and Biogeographic Research in the Colchicum Family

    Författare :Annika Vinnersten; Kåre Bremer; Bertil Nordenstam; Jerrold I Davis; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Biology; biogeography; Colchicaceae; colchicine; dating; phylogeny; taxonomy; Biologi; Biology; Biologi;

    Sammanfattning : This thesis concerns the history and the intrafamilial delimitations of the plant family Colchicaceae. A phylogeny of 73 taxa representing all genera of Colchicaceae, except the monotypic Kuntheria, is presented. LÄS MER

  4. 13. Catching Mercury : Mercury in Lake Vänern and Swedish catchments

    Författare :Peter Wihlborg; Lars Hylander; Linköpings universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; mercury; deposition; budget; sediments; retention; catchments; dating; kvicksilver; deposition; budget; retention; avrinningsområden; datering; Water in nature and society; Vatten i natur och samhälle;

    Sammanfattning : Vänern och dess sediment har under 1900-talet varit en av Sveriges mest kvicksilver (Hg) kontaminerade miljöer. 47 sedimentprofiler tagna 2001 analyserades for total Hg och temporala och spatiala mönster påvisades. Av den direkta Hg tillförseln 1918-2001 återfinns c:a 30 ton i bottensedimenten. LÄS MER

  5. 14. Late Quaternary ice sheet history and dynamics in central and southern Scandinavia

    Författare :Timothy Johnsen; Helena Alexanderson; James T. Teller; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Scandinavian ice sheet; ice sheet dynamics; luminescence dating; cosmogenic exposure dating; geochronology; moraine; interstadial; deglaciation; nunatak; Quaternary geology; Kvartärgeologi; kvartärgeologi; Quarternary Geology;

    Sammanfattning : Recent work suggests an emerging new paradigm for the Scandinavian ice sheet (SIS); one of a dynamically fluctuating ice sheet. This doctoral research project explicitly examines the history and dynamics of the SIS at four sites within Sweden and Norway, and provides results covering different time periods of glacial history. LÄS MER

  7. 15. Investigations of temporal changes in climate and the geomagnetic field via high-resolution radiocarbon dating

    Författare :Anette Mellström; Kvartärgeologi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; wiggle-matching; Radiocarbon dating; 14C; 2800 cal BP; climate change; solar activity; palaeomagnetism; lake sediments; varves; post-depositional remanent magnetisation; PDRM; lock-in; peat deposits; Sweden;

    Sammanfattning : Geological archives have shown periods of abrupt climate change in the relatively stable Holocene epoch (last ca. 11 700 years). One of these periods was around 2800 cal BP. Several records, mainly from Europe, reveal a shift towards wetter, cooler and windier conditions. LÄS MER