Sökning: "Stefan Bengtson"

Hittade 3 avhandlingar innehållade orden Stefan Bengtson.

1. 1. Aspects of problematic fossils in the early palaeozoic

   Författare :Stefan Bengtson; Uppsala universitet; []
   Nyckelord :NATURAL SCIENCES; NATURVETENSKAP;

   Sammanfattning : .... LÄS MER

3. 2. Ocean chemistry and the evolution of multicellularity

   Författare :Emma U. Hammarlund; Stefan Bengtson; Donald Canfield; Nils Holm; Graham Budd; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Geochemistry; biology; paleontology; evolution; multicellularity; geokemi; Geochemistry;

   Sammanfattning : Oxygen has been assumed to be a vital trigger for the evolution of multicellular life forms on Earth, partly based on its power to promote substantial energy flux in cell respiration and partly as biosynthesis of compounds like collagen require oxygen. However, the co-evolution of large life and the Earth’s chemical environment is not well understood at present, and there is particular disagreement in the field about whether the Cambrian explosion of animal life forms was a chemical or biological event. LÄS MER

4. 3. The Search for Life on Mars - Preparation for Sample Return

   Författare :Tomas Hode; Stefan Bengtson; John Hayes; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Earth sciences; Geovetenskap;

   Sammanfattning : The purpose of the thesis work has been to develop methods and concepts to aid in the search, detection and assessment of ancient microfossils here on Earth as a guide to the search for ancient life on Mars. The intention has been to identify and characterize environments on Earth that may be considered analogous to Martian environments and in which fossil preservation is expected to be good, and to develop and apply methods to characterize the isotopic and chemical composition of possible traces of life in order to assess their biogenicity and biological affinities. LÄS MER