Disentangling and ranking the influences of multiple environmental factors on plant and soil-dwelling arthropod assemblages in a river rhine floodplain area

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Gait optimization and energetics of ballistic walking for an underactuated biped with knees

In this paper, we study gait optimization of ballistic walking in order to understand the natural dynamics of an underactuated biped with knees. We also propose applications for our understandings. Our optimization problem is solved by fixing energy levels, and then, we attempt to explain how optimal gaits are formed by examining the role of each joint in speeding up. In addition, we explain some natural characteristics of walking. Based on the results, we propose a new cost function to generate various walking gaits, including the optimum. Finally, we evaluate and discuss the energy efficiency of our ballistic walker and other bipedal walkers including humans.clos

Heavy-metal concentrations in small mammals from a diffusely polluted floodplain : importance of species- and location-specific characteristics.

The soil of several floodplain areas along large European rivers shows increased levels of heavy metals as a relict from past sedimentation of contaminants. These levels may pose risks of accumulation in food webs and toxicologic effects on flora and fauna. However, for floodplains, data on heavy-metal concentrations in vertebrates are scarce. Moreover, these environments are characterised by periodical flooding cycles influencing ecologic processes and patterns. To investigate whether the suggested differences in accumulation risks for insectivores and carnivores, omnivores, and herbivores are reflected in the actual heavy-metal concentrations in the species, we measured the current levels of Zn, Cu, Pb, and Cd in 199 specimens of 7 small mammal species (voles, mice, and shrews) and in their habitats in a diffusely polluted floodplain. The highest metal concentrations were found in the insectivorous and carnivorous shrew, Sorex araneus. Significant differences between the other shrew species, Crocidura russula, and the vole and mouse species was only found for Cd. The Cu concentration in Clethrionomys glareolus, however, was significantly higher than in several other vole and mouse species. To explain the metal concentrations found in the specimens, we related them to environmental variables at the trapping locations and to certain characteristics of the mammals. Variables taken into account were soil total and CaCl2-extractable metal concentrations at the trapping locations; whether locations were flooded or nonflooded; the trapping season; and the life stage; sex; and fresh weight of the specimens. Correlations between body and soil concentrations and location or specimen characteristics were weak. Therefore; we assumed that exposure of small mammals to heavy-metal contamination in floodplains is significantly influenced by exposure time, which is age related, as well as by dispersal and changes in foraging and feeding patterns under influence of periodic flooding