Blar i forfatter "Siefken, Sandra Katharina Christiane"

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    • Seasonal changes in the Tapetum lucidum as an adaptation to winter darkness in reindeer 

      Siefken, Sandra Katharina Christiane (Master thesis; Mastergradsoppgave, 2010-05-15)
      Reindeer (Rangifer tarandus tarandus) live at high latitudes and are therefore exposed to extreme changes in environmental illumination. In winter they spend months in relative darkness, in summer they are exposed to months of continuous brightness. Previous investigations have revealed a shift in the wavelength of the light being reflected by the tapetum lucidum (TL) between winter and summer. Since ...

    • Shifting mirrors: adaptive changes in retinal reflections to winter darkness in Arctic reindeer 

      Stokkan, Karl-Arne; Folkow, Lars; Dukes, Juliet; Neveu, Magella; Hogg, Chris R; Siefken, Sandra Katharina Christiane; Dakin, Steven C; Jeffery, Glen (Journal article; Tidsskriftartikkel; Peer reviewed, 2013-12-22)
      Arctic reindeer experience extreme changes in environmental light from continuous summer daylight to continuous winter darkness. Here, we show that they may have a unique mechanism to cope with winter darkness by changing the wavelength reflection from their tapetum lucidum (TL). In summer, it is golden with most light reflected back directly through the retina, whereas in winter it is deep ...