Multi-generation studies with Chironomus riparius--effects of low tributyltin concentrations on life history parameters and genetic diversity

While toxicological data are available for numerous chemicals from standard tests, little is known on effects of pollutants over several generations or regarding chronic effects of chemicals on genetic diversity. Within the experiments, effects of the model pollutant tributyltin (TBT) were investigated over eleven generations at a sublethal TBT concentration of 4.46 μg as Sn kg⁻¹ sediment dw on life-cycle parameters and genetic variability of Chironomus riparius. Moreover, the adaptation potential towards TBT was determined. This experimental design enables the identification of TBT effects on life-cycle parameters and the determination of a potential extinction risk caused by chronic exposure. Furthermore, effects on the genetic structure can be determined, which are not predictable based solely on knowledge of the toxic mode of action of the chemical.

Genetic variety was determined via microsatellite analysis, measuring individual length differences of highly variable satellite DNA fragments. For the identification of changes in tolerances towards the stressor, acute and chronic toxicity experiments were conducted.

During the multi-generation study, significant effects on development and reproduction were determined. For some generations, the emergence was significantly (p < 0.05) delayed under TBT exposure. Reproduction seems to be a sensitive parameter as well, whereby females laid significantly larger egg masses (p < 0.05) in the latter generations. TBT did not affect the population growth rate nor the genetic variability, while clear deviations from the Hardy–Weinberg equilibrium appeared. The study also provides strong evidence for the acquirement of a higher tolerance towards the stressor in the TBT-exposed group.     

Managing relationship conflict and the effectiveness of organizational teams

Past research has revealed that team effectiveness and satisfaction suffer when teams experience relationship conflict—conflict related to interpersonal issues, political norms and values, and personal taste. This study examined how teams should respond to these conflicts. Three types of conflict responses were studied: collaborating responses, contending responses, and avoiding responses. A field study involving a heterogeneous sample of teams performing complex, non‐routine task showed that collaborating and contending responses to relationship conflict negatively relate to team functioning (i.e., voice, compliance, helping behavior) and overall team effectiveness, while avoiding responses were associated with high team functioning and effectiveness. It is suggested that collaborating and contending responses to relationship conflict distract team members from their tasks, while avoiding responses appear more functional in that they allow team members to pursue task performance. Copyright © 2001 John Wiley & Sons, Ltd.     

Testing implementation conditions for in-vehicle information systems

In the European 6th Framework Programme, fundamental research in the field of technology assessment regarding behavioural effects was conducted in the HASTE (Human machine interface And the Safety of Traffic in Europe) project. Methods, metrics and scenarios for the exploration of safety problems related to IVIS (in-vehicle information systems) were defined and applied to the evaluation of surrogate systems in the laboratory originally and real systems subsequently, in laboratories and field studies. The results of the laboratory and field studies led to the formulation of guidelines for a standardized test regime regarding existing and newly developed IVIS. In this way the HASTE project has succeeded in the development of a valid, reliable and efficient tool that may aid testing authorities in their safety evaluation of IVIS.     

75 Jahre Theorie des expandierenden Kosmos: Friedmann Modelle und der “Einstein–Limit”

  Die geschichtliche Entwicklung der kosmologischen Modelle für den homogen–isotropen Kosmos, beginnend mit Alexander Friedmanns epochalen Arbeiten (1922 und 1924) bis zur heutigen Diskussion aktueller Modelle wird dargestellt. Eine kardinale Rolle spielt die offene Frage: Besteht die Materie des Kosmos zum weit überwiegenden Teil aus nicht–baryonischer (sog. exotischer) Dunkel–Materie oder reicht die gesamte baryonische Materie aus, die aus den bekannten Atomen und Molekülen besteht, um die Entwicklung des Kosmos zu verstehen. Auch von der normalen (baryonischen) Materie im Kosmos ist nur ein geringer Anteil (etwa 20 5 Prozent) in leuchtenden Objekten (Sterne, Gas, Staub) direkt beobachtbar. Im Abschnitt 3 wird der “Einstein–Limit” für die kosmologische Konstante erl?utert und eine leicht einsichtige Herleitung des Zahlenwertes gegeben.