Zum Problem der Elimination der Nestgeschwister beim LerchenkuckuckTapera naevia

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Improved method for routine determination of nicotine and its main metabolites in biological fluids

Extrelut^R extraction and glass capillary gas chromatography were applied to the routine determination of nicotine and its metabolites cotinine, nicotine-1′-N-oxide and cotinine-1-N-oxide in urine and plasma. After extraction of nicotine and cotinine both N-oxides and phendimetrazine-N-oxide (used as internal standard) were reduced to their bases by SO₂ on-column and eluted by a mixture of diethyl ether and dichloromethane. The minimum detectable concentrations are 0.03 μg/ml for urinary nicotine and cotinine and 0.1 μg/ml for the N-oxides. In plasma samples the corresponding values are 5 ng/ml and 15 ng/ml, respectively, with sample values as small as 2 ml. The advantage of the direct determination of all four compounds of interest in one sample reduced the amount of plasma required. The straightforward and rapid extraction and reduction procedure as well as the long-term stability of the gas chromatographic separation system make the method suitable for routine application.     

Die Wirkung des Grünlichtes auf die Fruchtkörperbildung bei Didymium eunigripes

Zusammenfassung Versuche über die Wirkung verschiedener Lichtqualitäten (Farbgläser von Schott, Mainz) auf die Sporangienbildung bei Didymium eunigripes ergaben Sporangienbilding mit den Filtern UG1, BG12, BG18 und RG5, dagegen keine oder kaum mit den Filtern VG9 und UG8. Das bedeutet, daß mit allen Lichtqualitäten die Sporangienbildung induziert werden kann, mit Ausnahme von grünem Licht und Infrarot.Eine besondere Methode wird beschrieben, um den Lichtwirkungstest sicher und möglichst empfindlich zu gestalten. — Die Plasmodien wurden 4 Tage, bevor sie belichtet werden sollten, auf ältere, standardisierte Kulturen von Oscillatoria animalis übergeimpft.Zur Untersuchung, ob Grünlicht unwirksam ist oder die Sporangienbildung hemmt, wurden Mischlichtversuche angestellt, bei denen zu einer Dosis Rotlicht, die für eine 100% ige Sporangienbildung ausreichend war, abgestufte Mengen Grünlichtes gegeben wurden. Es zeigte sich, daß der Prozentsatz Plasmodien, die zur Sporangienbildung kamen, mit steigenden Grünlichtgaben geringer wurde. Grünlicht wirkt der fördernden Bestrahlung mit anderen Lichtarten also entgegen.Herrn Prof. Dr. J. Straub danke ich für die stete Förderung der Arbeit.     

Nachträge zur Flora und Vegetation des Olymps

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Zur Mechanik des Hitzetodes pflanzlicher Zellen (Vorläufige Mitteilung)

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When Challenging Art Gets Liked: Evidences for a Dual Preference Formation Process for Fluent and Non-Fluent Portraits

Although fluency theory predominates psychological research on human aesthetics, its most severe limitation may be to explain why art that challenges or even violates easy processing can nevertheless be aesthetically rewarding. We discuss long-standing notions on art’s potential to offer mental growth opportunities and to tap into a basic epistemic predisposition that hint at a fluency counteracting aesthetic pleasure mechanism. Based on divergent strands of literature on empirical, evolutionary, and philosophical aesthetics, as well as research on disfluency, we presumed that challenging art requires deliberate reflexive processing at the level of “aboutness” in order to be experientially pleasing. Here, we probed such a cognitive mastering mechanism, achieved by iterative cycles of elaboration, as predicted by our model of aesthetic experiences. For the study, two kinds of portraits were applied, one associable to a high fluency and one to a high stimulation potential (according to results of an extensive rating study). In Experiment 1, we provided a repeated evaluation task, which revealed a distinctive preference effect for challenging portraits that was absent in the visual exposition conditions of a familiarity and a mere exposure task (Experiment 2). In a follow-up task (Experiment 3) this preference effect was observed with a novel and more encompassing pool of portraits, which corroborated its stability and robustness. In an explorative stimulus-transfer task (Experiment 4), we investigated the presumed underlying mechanism by testing whether the observed effect would generalize onto novel portraits of the same artist-specific styles. Results discounted an alternative interpretation of a perceptual adaptation effect and hinted at meaning-driven mental activity. Conjointly, findings for inexperienced viewers were indicative of an elaboration based mastering mechanism that selectively operated for mentally challenging portraits. Moreover, findings were in line with a dual-process view of human preference formation with art. Theoretical implications and boundary conditions are discussed.     

Biodiversity effects on ecosystem functioning: emerging issues and their experimental test in aquatic environments

Recent experiments, mainly in terrestrial environments, have provided evidence of the functional importance of biodiversity to ecosystem processes and properties. Compared to terrestrial systems, aquatic ecosystems are characterised by greater propagule and material exchange, often steeper physical and chemical gradients, more rapid biological processes and, in marine systems, higher metazoan phylogenetic diversity. These characteristics limit the potential to transfer conclusions derived from terrestrial experiments to aquatic ecosystems whilst at the same time provide opportunities for testing the general validity of hypotheses about effects of biodiversity on ecosystem functioning. Here, we focus on a number of unique features of aquatic experimental systems, propose an expansion to the scope of diversity facets to be considered when assessing the functional consequences of changes in biodiversity and outline a hierarchical classification scheme of ecosystem functions and their corresponding response variables. We then briefly highlight some recent controversial and newly emerging issues relating to biodiversity‐ecosystem functioning relationships. Based on lessons learnt from previous experimental and theoretical work, we finally present four novel experimental designs to address largely unresolved questions about biodiversity‐ecosystem functioning relationships. These include (1) investigating the effects of non‐random species loss through the manipulation of the order and magnitude of such loss using dilution experiments; (2) combining factorial manipulation of diversity in interconnected habitat patches to test the additivity of ecosystem functioning between habitats; (3) disentangling the impact of local processes from the effect of ecosystem openness via factorial manipulation of the rate of recruitment and biodiversity within patches and within an available propagule pool; and (4) addressing how non‐random species extinction following sequential exposure to different stressors may affect ecosystem functioning. Implementing these kinds of experimental designs in a variety of systems will, we believe, shift the focus of investigations from a species richness‐centred approach to a broader consideration of the multifarious aspects of biodiversity that may well be critical to understanding effects of biodiversity changes on overall ecosystem functioning and to identifying some of the potential underlying mechanisms involved.