Über Fernwirkung von Blei auf Pflanzen

Zusammenfassung Durch die obigen 3 Versuchsreihen mit 875 Keimen vonSinapis alba war eine sichere Fernwirkung von Blei nicht feststellbar. Vielleicht könnte man eher von einer sehr schwachen Wachstumsförderung als von einer Wachstumshemmung sprechen.Herrn Prof. Dr. Rosemann danken wir verbindlichst für die Überlassung eines Laboratoriums.     

Die Symbiose in den Wurzelknöllchen der Podocarpeen

Ohne ZusammenfassungMit 9 Textabbildungen.     

Die züchterische Bearbeitung des Kulturchampignons (Psalliota bispora Lge.) Probleme und erste eigene Ergebnisse

Ohne ZusammenfassungMit 9 AbbildungenHerrn Prof. Dr.Hans Stubbe zum 60. Geburtstag gewidmet.     

Über das Verhalten des Nucleolus während der Kernteilung

Ohne Zusammenfassung     

Dissecting the repeatability of female choice in the grasshopper Chorthippus biguttulus

Repeatable differences in preference between females are a prerequisite for the evolution of female choice. Existing studies have concentrated on the repeatability of female preference for the male trait eliciting the highest female response but have rarely dealt with female choosiness and response rate, which are also important traits for the evolution of female choice and can mimic repeatable variation in preference. We used a method devised to disentangle the effects of preference, choosiness and response rate to examine the repeatability of female choice for acoustic signals in the grasshopperChorthippus biguttulus . We stimulated females with artificial courtship signals that varied in one signal trait and recorded the number of acoustic responses of the females in two sessions separated by several days. Using a normal distribution function within a nonlinear regression between signalling trait and female response rate, we independently calculated values for female preference, choosiness and maximum response rate for the two sessions. All three aspects of female choice showed significant repeatability indicating large differences between females. This method will also be suitable for measuring the heritability of female preference, a crucial question regarding the evolution of female choice. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.     

Postural Control in Dual-Task Situations: Does Whole-Body Fatigue Matter?

Postural control is important to cope with demands of everyday life. It has been shown that both attentional demand (i.e., cognitive processing) and fatigue affect postural control in young adults. However, their combined effect is still unresolved. Therefore, we investigated the effects of fatigue on single- (ST) and dual-task (DT) postural control. Twenty young subjects (age: 23.7 ± 2.7) performed an all-out incremental treadmill protocol. After each completed stage, one-legged-stance performance on a force platform under ST (i.e., one-legged-stance only) and DT conditions (i.e., one-legged-stance while subtracting serial 3s) was registered. On a second test day, subjects conducted the same balance tasks for the control condition (i.e., non-fatigued). Results showed that heart rate, lactate, and ventilation increased following fatigue (all p < 0.001; d = 4.2–21). Postural sway and sway velocity increased during DT compared to ST (all p < 0.001; d = 1.9–2.0) and fatigued compared to non-fatigued condition (all p < 0.001; d = 3.3–4.2). In addition, postural control deteriorated with each completed stage during the treadmill protocol (all p < 0.01; d = 1.9–3.3). The addition of an attention-demanding interference task did not further impede one-legged-stance performance. Although both additional attentional demand and physical fatigue affected postural control in healthy young adults, there was no evidence for an overadditive effect (i.e., fatigue-related performance decrements in postural control were similar under ST and DT conditions). Thus, attentional resources were sufficient to cope with the DT situations in the fatigue condition of this experiment.