Ronald Heyer

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Biogas production from energy crops and biodegradable waste is one of the major sources for renewable energies in Germany. Within a biogas plant (BGP) a complex microbial community converts biomass to biogas. Unfortunately, disturbances of the biogas process occur occasionally and cause economic losses of varying extent. Besides technical failures the(More)
In biogas plants agricultural waste and energy crops are converted by complex microbial communities to methane for the production of renewable energy. In Germany, this process is widely applied namely in context of agricultural production systems. However, process disturbances, are one of the major causes for economic losses. In addition, the conversion of(More)
Jo determine the adaptive strategies frogs utilize to exploit tropical seasonal environments, a 10 month study of tadpole ecological interactions was undertaken at the Sakaerat Experiment Station, located approximately 250 km ME of Bangkok. The temporal distribution patterns of larval species occurrence for several ponds show the following: 1) all the(More)
The antiepileptic drugs phenobarbital and phenytoin were determined in serum by enzyme immunoassay (Emit, Syva Corp.) and gas-liquid chromatography. The Emit assays were mechanized by the use of an Eppendorf analyzer 5010. The precision of the Emit system was sufficient (coefficient of variation within series 6-13% and from day to day 8-15% with various(More)
Complex microbial communities are the functional core of anaerobic digestion processes taking place in biogas plants (BGP). So far, however, a comprehensive characterization of the microbiomes involved in methane formation is technically challenging. As an alternative, enriched communities from laboratory-scale experiments can be investigated that have a(More)
Leptodactylus validus has an unusual distribution, inhabiting Trinidad, Tobago, and the Lesser Antilles, but not the mainland of South America. This distribution is inconsistent with other distribution patterns observed for these islands. Although slight variation in adult morphology has been observed among the different island populations of L. validus,(More)
The applicability and performance of a micro liquid-liquid extraction method for trace analysis of organic compounds in drinking water is reported. Tap water samples of 400 ml are saturated with sodium chloride and extracted once with 500 microliters of toluene. Extracts are analyzed directly without further treatment by gas chromatography using(More)
Biochemical techniques have opened up new sources of data with relevance to many questions in ecological and evolutionary biology. Currently, molecular analytical techniques range from protein assays to determination of DNA sequences. Not all current molecular techniques require frozen tissues, but frozen tissues, if properly sampled and stored, are(More)
Ecological data were gathered on five sympatric species of Leptodactylus over a two month period from a study site in Amazonian Ecuador: L. discodactylus, L. knudseni, L. mystaceus, L. pentadactylus, and L. wagneri. Three species have broad niches [L, knudseni, L. mystaceus, and L. wagneri); two have narrower niches (L. pentadactylus, L. discodactylus). L.(More)