Earthquake rupture dynamics frozen in exhumed ancient faults

Most of our knowledge about co-seismic rupture propagation is derived from inversion and interpretation of strong-ground-motion seismograms, laboratory experiments on rock and rock-analogue material, or inferred from theoretical and numerical elastodynamic models. However, additional information on dynamic rupture processes can be provided by direct observation of faults exhumed at the Earth's surface. Pseudotachylytes (solidified friction-induced melts) are the most certain fault-rock indicator of seismicity on ancient faults. Here we show how the asymmetry in distribution and the orientation of pseudotachylyte-filled secondary fractures around an exhumed fault can be used to reconstruct the earthquake rupture directivity, rupture velocity and fracture energy, by comparison with the theoretical dynamic stress field computed around propagating fractures. In particular, the studied natural network of pseudotachylytes is consistent with a dominant propagation direction during repeated seismic events and subsonic rupture propagation close to the Rayleigh wave velocity.     

Catecholamine-containing nerve fibres in the hind-gut of the crayfishAstacus astacus L. (Crustacea,decapoda)

Zusammenfassung Katecholamin enthaltende Nervenfasern im Enddarm vonAstacus astacus (L.) werden mit Hilfe vonFalcks undHillarps spezifischer Fluoreszenzmethode gezeigt. Die Fasern, die eine grüne Fluoreszenz abgeben, wurden in Nervenplexen der zirkulären und der längsgehenden Muskelschichten des Darmes beobachtet. Es wird angenommen, dass diese Fluoreszenz durch Noradrenalin zustande kommt.

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The research reported in this document has been sponsored by the Swedish Natural Science Research Council under grant No. 99-35.     

Differential amine depletion from cardiac adrenergic nerves by Segontin

Zusammenfassung Selbst bei hohen Dosen von Segontin wird eine beachtliche Menge von Noradrenalin im Herz zurückgehalten. Fluoreszenzhistochemische Untersuchungen nach verschiedenen Dosen von Segontin machen wahrscheinlich, dass dieser Aminrest in den Gefässnerven enthalten ist, während der vollständige Schwund der Überträgersubstanz in den Muskelnerven beobachtet wird.

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Supported by the Association for the Aid of Crippled Children, New York and by Farbwerke Hoechst AG (Hoechst Anilin AB, Göteborg), who also generously supplied the Segontin.     

Effect of cardiac catecholamine depletion through sympathectomy on spontaneous ventricular fibrillation during induced hypothermia in cats

Zusammenfassung Versuche mit Katzen haben gezeigt, dass Hypothermie in einer Reduzierung des Noradrenalingehaltes im Herzen resultiert (zentrale Aktivierung). Der Versuch, den Noradrenalingehalt im Herzen durch Sympathektomie 2 oder 3 Tage vor Unterkühlung zu reduzieren, ergibt aber keinen signifikanten Schutz gegen spontanes Ventrikelflimmern. Dieses Verhalten beruht wahrscheinlich auf der schnellen Entwicklung der Empfindlichkeitssteigerung des Myokards gegenüber Katecholaminen und besonders Noradrenalin, das von adrenergen Herznerven freigesetzt wird (bei unvollständiger Denervierung).

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Supported by grants from the Association for the Aid of Crippled Children, New York; and from Anna-Lisa and Sven Eric Lundgren's Foundation.     

Species-specific responses of Late Quaternary megafauna to climate and humans

Despite decades of research, the roles of climate and humans in driving the dramatic extinctions of large-bodied mammals during the Late Quaternary period remain contentious. Here we use ancient DNA, species distribution models and the human fossil record to elucidate how climate and humans shaped the demographic history of woolly rhinoceros, woolly mammoth, wild horse, reindeer, bison and musk ox. We show that climate has been a major driver of population change over the past 50,000 years. However, each species responds differently to the effects of climatic shifts, habitat redistribution and human encroachment. Although climate change alone can explain the extinction of some species, such as Eurasian musk ox and woolly rhinoceros, a combination of climatic and anthropogenic effects appears to be responsible for the extinction of others, including Eurasian steppe bison and wild horse. We find no genetic signature or any distinctive range dynamics distinguishing extinct from surviving species, emphasizing the challenges associated with predicting future responses of extant mammals to climate and human-mediated habitat change.     

Exchange of water between the harbor porpoise,Phocoena phocoena,and the environment

Summary During determination of total body water and net water turnover in the harbor porpoise,Phocoena phocoena, it was demonstrated that the porpoise exchanged water with an isosmotic environment by way of free diffusion and with hypo- or hyperosmotic environment by way of osmosis.