Holocene recolonization and extinction of the pond turtle, Emys orbicularis (L., 1758), in Europe

We reconstruct the Holocene range fluctuations of the European pond turtle (Emys orbicularis) for northern and Central Europe. Based on 529 subfossil records and radiocarbon dating of critical finds, we provide evidence that E. orbicularis experienced a rapid range expansion with Holocene warming. Phylogeographic data argue for a colonization of northern and Central Europe from a glacial refuge located in the south-eastern Balkans. Already in the Late Preboreal (9100–8600 cal BC) the species occurred in northern Central Europe and was widespread in Denmark and southern Sweden (Skåne) during the Boreal (8600–7100 cal BC). The maximum range extension occurred during the Holocene climatic optimum (Atlantic: 7100–3750 cal BC), with records in southern England, middle Sweden, and northern Estonia. After the early Subboreal (3750–1750 cal BC) northern populations collapsed, coinciding with a climatic cooling and oceanization. Northern populations were most likely established via long distance dispersal (rafting using rivers debouching in the North and Baltic Seas); after northern Europe was reached, a minimum dispersal of 50 km per 100 years may be hypothesized for the Boreal.     

A Degenerate Bifurcation In The Hénon-Heiles Family

The normalised Hénon–Heiles family exhibits a degenerate bifurcation when passing through the separable case =0. We clarify the relation between this degeneracy and the integrability at =0. Furthermore we show that the degenerate bifurcation carries over to the Hénon–Heiles family itself.     

Geological and environmental factors involved in natural gas accidents

Variability in soil mineralogy, texture, and pavement cover are involved in events leading to undetected gas leaks and subsequent explosions in Bowie, Md. and Washington, D.C. These geologic parameters are involved in selectively removing the gas odorant additive t-butyl merceptan as the gas came into contact with the soil near the pipeline breaks. This removal resulted in an accumulation of combustable natural gas without detectable odor. Soil samples from drill holes and near surface sites were utilized to map soil type, texture, and mineralogy. Residual methane content of the samples was also measured. The data from two dissimilar sites indicates that finegrained soil enriched in montmorillonite preferentially removes the odorant.