Sökning: "Shell evolution"

Visar resultat 1 - 5 av 44 avhandlingar innehållade orden Shell evolution.

1. 1. Uncovering the Past through ancient DNA : The Fate and Legacy of the last hunter-gatherers in Western Europe and Northwestern Africa

   Författare :Luciana G. Simões; Mattias Jakobsson; Torsten Günther; Cristina Valdiosera; Emma Svensson; Martin Sikora; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; human evolution; archaeogenomics; ancient DNA; population genetics; hunter-gatherer; Populationsbiologi; Population Biology; Genetik; Genetics;

   Sammanfattning : The genetic analysis of ancient human remains has revolutionized the study of human history, opening a direct window onto the demographic and evolutionary events that shaped our species' past. I use state-of-the-art ancient DNA methodologies, from sample collection and DNA extraction to data analysis, to study the ancient past of the western Mediterranean region, where climate does not favour DNA preservation. LÄS MER

3. 2. Shell repair as a response to attempted predation in some Palaeozoic and younger gastropods

   Författare :Anna Lindström; John S. Peel; Jan Ove R. Ebbestad; Euan N. K. Clarkson; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Earth sciences; Gastropoda; predation; shell morphology; shell repair; Palaeozoic; Geovetenskap; Earth sciences; Geovetenskap;

   Sammanfattning : Traces of unsuccessful predatory attacks can be found in the hard parts of shell-bearing organisms as repaired shell injuries and are often preserved in the fossil record. These repaired shell injuries can help to deduce the relationship between predator and prey in the past. LÄS MER

4. 3. Engineering inorganic nanostructured composites for boosting H2 and O2 evolution reactions

   Författare :Getachew Solomon; Isabella Concina; Alberto Vomiero; Sixto Gimenez; Luleå tekniska universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Hydrogen evolution HER ; Oxygen evolution reaction OER ; Oxygen reduction reaction ORR ; Water splitting; Electrocatalyst; Atomic layer deposition; Core-shell structure; Experimentell fysik; Experimental Physics;

   Sammanfattning : Hydrogen is considered a promising energy source with zero emission of CO2; it can provide higher energy density compared to other sources of energy. The amount at which H2 is produced, and the method of production need further improvement for the advancement of hydrogen energy technologies. LÄS MER

5. 4. Modelling the Winds from Carbon Rich AGB Stars : Implications for Stellar Evolution and the Chemical Evolution of Galaxies

   Författare :Lars Mattsson; Uppsala universitet; []
   Nyckelord :;

   Sammanfattning : Stars on the AGB are known to lose mass at high rates (10-8 - 10-4 Msun/yr) through slow winds (20 km/s), enriching the inter stellar medium with newly synthesised elements. We explore how the mass loss for C-rich AGB stars depends on the basic stellar parameters by computing a large grid of wind models. LÄS MER

7. 5. Evolution of the earliest molluscs

   Författare :Alexander P. Gubanov; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Earth sciences; Geovetenskap; Earth sciences; Geovetenskap; Historical Geology and Paleontology; historisk geologi och paleontologi;

   Sammanfattning : The first helcionelloid molluscs appeared in the late Vendian and were forerunners ofthe sudden molluscan diversification of the Cambrian explosion. The diversification ofMollusca coincided with global changes in the lithosphere, hydrosphere, atmosphere,and biosphere coincident with the break-up of the Late Proterozoic supercontinentRodinia, a distinct shift in oceanic water geochemistry, and the sudden abundance ofshelled multicellular organisms. LÄS MER