Sökning: "fossil"

Visar resultat 21 - 25 av 1056 avhandlingar innehållade ordet fossil.

  1. 21. The Evolutionary Significance of Cambrian Ecdysozoan Trace Fossils

    Författare :Giannis Kesidis; Graham Budd; Liam Herringshaw; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Cambrian; trace fossil; Cruziana; Rusophycus; Treptichnus; Ecdysozoa;

    Sammanfattning : The origin of most of the animal phyla is tied to the Cambrian explosion, a rapid diversification event that took place from about 540 million years ago. This diversification is coupled with a great number of concurrent metazoan body plan innovations such as the development of the coelom, antagonistic muscles and a through-gut. LÄS MER

  3. 22. Comparative Assessment of Fuel-Based Systems for Space Heating

    Författare :Åsa Karlsson; Miljö- och energisystem; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Energiforskning; Energy research; cogeneration; district heating; electric heating; external cost; carbon dioxide mitigation; detached houses; fossil fuels; Energy systems; bioenergy;

    Sammanfattning : Replacing fossil fuels by biofuels and increasing energy efficiency are often considered to be options for reducing the net emission of greenhouse gases. This thesis presents the results of analyses of energy efficiency, emission and cost of whole energy system chains, from the natural resource to the end user when heating detached houses in a Swedish context. LÄS MER

  4. 23. Origin and the evolution of diatoms through the integration of paleontology and phylogenetics

    Författare :Karolina Brylka; Berggrundsgeologi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; diatoms; evolution; fossil record; Cretaceous; molecular evolution; Mesozoic; silicon transporter proteins; gene duplication;

    Sammanfattning : Diatoms, the prominent photosynthetic eucaryotes, have inhabited the world’s oceans for at least the past 120 Ma since their first appearance in the Lower Cretaceous. There are also records of older diatoms, from the Jurassic dating to ca. 172 Ma and ca. 165 Ma, however these are poorly documented. LÄS MER

  5. 24. Landskap och ödesbölen : Jämtland före, under och efter den medeltida agrarkrisen

    Författare :Hans Antonson; Mats Widgren; Ulf Jansson; Stefan Brink; Stockholms universitet; []
    Nyckelord :SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; Agrarian history; Early modern period; Sweden; Brunflo; Revsund; Sundsjö; Parish; Settlement; Deserted farms; Hamlet; Farmstead; The Black Death; Climate; Change of agrarian regime; Ownership; Forms of cultivation; Historical maps; Medieval diplomas; Registers of taxpayers; Fossil farmland; Field mapping; Archaeology; Human geography; Kulturgeografi;

    Sammanfattning : This study examines landscape change in the Province of Jämtland during c. 1000–1750 AD. Settlement and arable cultivation are two of the most important sources in this study. LÄS MER

  7. 25. Survival of the Unfit : Path Dependence and the Estonian Oil Shale Industry

    Författare :Rurik Holmberg; Staffan Laestadius; Mats Bladh; Mats Söderström; Nick von Tunzelmann; Linköpings universitet; []
    Nyckelord :SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; Estonia; oil shale; path dependence; lock-in; institutions; knowledge; Sweden; innovation; Soviet Union; technology; systems; energy; shale oil; electricity; fossil fuel; environment; economy; Technology and social change; Teknik och social förändring;

    Sammanfattning : Estonia is the only country in the world, which is totally dependent on oil shale in its energy system. Although this fossil fuel exists in enormous quantities around the world, it has so far not been utilized on a larger scale. The reasons for this have been both economic and, in recent times, ecological. LÄS MER