Sökning: "extinction"

Visar resultat 11 - 15 av 267 avhandlingar innehållade ordet extinction.

  1. 11. Limiting conditions for a sustained flame over condensed fuels : Analysis by experiments and stagnant layer theory

    Författare :Frida Vermina Plathner; Avdelningen för Brandteknik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Critical mass flux; diffusion flame; extinction; sustained ignition; chemical heat of combustion; Convective heat transfer coefficient; external heat flux;

    Sammanfattning : Ignition and extinction characteristics of a material determine whether a fire will be initiated and grow. In fire safety engineering, where modellers deal with a multitude of materials, simplified thresholds are commonly used to determine when ignition and extinction occur. LÄS MER

  3. 12. Insect Diversity in Changing Landscapes

    Författare :Markus Franzén; Biologiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; växtparasitologi; Entomologi; plant parasitology; Zoology; Zoologi; Entomology; Ekologi; Ecology; butterfly; bee; dispersal; extinction; Djurekologi; Animal ecology;

    Sammanfattning : During recent decades, concern about the loss of biodiversity has increased. To change this negative trend there is an urgent need for effective conservation measures and there are ample evidence that conservation of organisms without an understanding of their ecology and behaviour is impossible. LÄS MER

  4. 13. A Multitype Branching Processes Approach to the Evolutionary Dynamics of Escape

    Författare :Maria Conceicao Serra; Göteborgs universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Galton-Watson branching processes; multitype; decomposable processes; population dynamics; extinction; mutation; path to escape; waiting time to escape; Galton-Watson branching processes;

    Sammanfattning : Evolutionary dynamics of escape is a recent development in theoretical biology. It is an attempt to predict possible patterns of population dynamics for a certain strain of viruses placed in a hostile environment. The only way to escape extinction for the virus is to find a new form better adapted to the new environment. LÄS MER

  5. 14. Species extinctions in food webs : local and regional processes

    Författare :Anna Eklöf; Bo Ebenman; Peter Münger; Marcel Holyoak; Linköpings universitet; []
    Nyckelord :Extinction; food web; metacommunity; dispersal; species loss; migration; habitat fragmentation; connectance; NATURAL SCIENCES; NATURVETENSKAP;

    Sammanfattning : Loss of biodiversity is one of the most severe threats to the ecosystems of the world. The major causes behind the high population and species extinction rates are anthropogenic activities such as overharvesting of natural populations, pollution, climate change and destruction and fragmentation of natural habitats. LÄS MER

  7. 15. The tempo and mode of evolution : a neontological reappraisal

    Författare :Melanie Monroe; Folmer Bokma; Pär Ingvarsson; Mikael Fortelius; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; birds; extinction; macroevolution; mammals; microevolution; punctuated equilibrium; speciation;

    Sammanfattning : The theory of “punctuated equilibrium” suggests that species evolve rapidly during or immediately upon speciation, “punctuating” long periods of little or no morphological evolution. Here I confirm that body size differences within clades of birds and mammals are best explained using a model of punctuated evolution. LÄS MER