Endlich der Beweis: Die Inschrift des Genter Altars entstand im 16. Jahrhundert

Über die berühmte Inschrift des Genter Altars, die die Brüder Hubert und Jan van Eyck als Urheber und das Vollendungsjahr 1432 nennt, gehen die Meinungen auseinander: die Forschung hält sie größtenteils für authentisch, doch gibt es auch gut begründete Zweifel. Die neuen Publikationen anlässlich der Restaurierung der Altaraußenseite kommen in dieser Frage zu einer eindeutigen Bestätigung der Forschungsmehrheit. Die restaurierten Rahmenleisten mit ihren Inschriften erlauben jedoch Beobachtungen, die bisher nicht möglich waren: Jetzt ist unverkennbar, dass der Quatrain gestalterische Merkmale aufweist, die sich von den Inschriften auf den anderen Werken Jan van Eycks grundsätzlich unterscheiden. Von Authentizität kann keine Rede mehr sein

Den Holocaust für arabischsprachige Geflüchtete unterrichten. Eine Analyse landeskundlicher DaF-Lehrbücher

Immer häufiger ist in Medien von einem arabischen Antisemitismus zu lesen, der durch die Flucht- und Migrationsbewegungen 2015 nach Deutschland kam. Für den Deutsch als Fremdsprache - Unterricht ergeben sich damit neue Herausforderungen, auch hinsichtlich der Gestaltung von Lehrwerken. Denn diese sind, so die Hypothese des Artikels, nicht geeignet einen arabischen Antisemitismus aufzubrechen

Den Holocaust für arabischsprachige Geflüchtete unterrichten. Eine Analyse landeskundlicher DaF-Lehrbücher

Immer häufiger ist in Medien von einem arabischen Antisemitismus zu lesen, der durch die Flucht- und Migrationsbewegungen 2015 nach Deutschland kam. Für den Deutsch als Fremdsprache - Unterricht ergeben sich damit neue Herausforderungen, auch hinsichtlich der Gestaltung von Lehrwerken. Denn diese sind, so die Hypothese des Artikels, nicht geeignet einen arabischen Antisemitismus aufzubrechen.With increasing frequency the media brings up an Arab antisemitism which came to Germany in the context of the refugee and migration movement since 2015. This leads to new challenges for the German as a foreign language education, also with regard to the planning of textbooks. Those are, as the article states, not suitable to counteract an Arab antisemitism

Flagellar sensilla in male and female European beewolves, Philanthus triangulum F. (Hymenoptera: Sphecidae)

We investigated the morphology of the antennal sensilla of a sphecid wasp, the European beewolf Philanthus triangulum, to provide an inventory for the species and to compare the sensillar equipment between the sexes. The density of sensilla increased from the base to the tip of the antennae. We distinguished nine different types of sensilla. One type has not yet been described in Hymenoptera. The large sensilla basiconica occurred only on the antennae of female beewolves. We discuss the functional significance of the difference between the sexes and compare our results with data from other sphecids and the honeybee Apis mellifera

Is the postpharyngeal gland of a solitary digger wasp homologous to ants? Evidence from chemistry and physiology

The postpharyngeal gland (PPG) was thought to be restricted to ants where it serves a crucial function in the generation of the colony odour. Recently, head glands that closely resemble the PPG of ants were discovered in females of a solitary digger wasp, the European beewolf. The function of this gland necessarily differs from ants: beewolf females apply the secretion of their PPG onto the bodies of paralysed honeybees that serve as larval provisions in order to delay fungus growth. Since ants and digger wasps are not closely related, the occurrence of this gland in these two taxa might either be due to convergent evolution or it is a homologous organ inherited from a common ancestor. Here we test the hypothesis that the PPGs of both taxa are homologous by comparing characteristics of chemical composition and physiology of the PPG of beewolves and ants. Based on reported characteristics of the PPG content of ants, we tested three predictions that were all met. First, the PPG of beewolves contained mainly long-chain hydrocarbons and very few compounds with functional groups. Second, the composition of hydrocarbons in the beewolf PPG was similar to that of the hemolymph. Taking the structure of the gland epithelium and the huge requirements of beewolf females for gland secretion into account this result suggests that the content of the PPG is also sequestered from the hemolymph in beewolves. Third, the chemical composition of the PPG and the cuticle was similar in beewolves since cuticular hydrocarbons derive either from the hemolymph or the PPG. Taking the considerable morphological similarities into account, our results support the hypothesis of a homologous origin of the PPG in beewolves and ants

Expressing best practices in (risk) analysis and testing of safety-critical systems using patterns

The continuing pervasion of our society with safety-critical cyber-physical systems not only demands for adequate (risk) analysis, testing and verification techniques, it also generates growing experience on their use, which can be considered as important as the tools themselves for their efficient use. This paper introduces workflow patterns to describe such best practices in a systematic way that efficiently represents this knowledge, and also provides a way to relate different patterns, making them easier to identify and use, and cover as wide a range of experiences as possible. The value of the approach is demonstrated using some pattern examples from a collection developed in the Artemis-project MBAT. Finally, the paper presents a wiki-based approach for developing and maintaining the pattern collection

Sexual selection and the evolution of male pheromone glands in philanthine wasps (Hymenoptera, Crabronidae)

Background: Sexual selection is thought to promote evolutionary changes and diversification. However, the impact of sexual selection in relation to other selective forces is difficult to evaluate. Male digger wasps of the tribe Philanthini (Hymenoptera, Philanthinae) scent mark territories to attract receptive females. Consequently, the organs for production and storage of the marking secretion, the mandibular gland (MG) and the postpharyngeal gland (PPG), are subject to sexual selection. In female Philanthini, these glands are most likely solely subject to natural selection and show very little morphological diversity. According to the hypothesis that sexual selection drives interspecific diversity, we predicted that the MG and PPG show higher interspecific variation in males than in females. Using histological methods, 3D-reconstructions, and multivariate statistical analysis of morphological characters, we conducted a comparative analysis of the MG and the PPG in males of 30 species of Philanthini and three species of the Cercerini and Aphilanthopsini, two related tribes within the Philanthinae. Results: We found substantial interspecific diversity in gland morphology with regard to gland incidence, size, shape and the type of associated secretory cells. Overall there was a phylogenetic trend: Ensuing from the large MGs and small PPGs of male Cercerini and Aphilanthopsini, the size and complexity of the MG was reduced in male Philanthini, while their PPG became considerably enlarged, substantially more complex, and associated with an apparently novel type of secretory cells. In some clades of the Philanthini the MG was even lost and entirely replaced by the PPG. However, several species showed reversals of and exceptions from this trend. Head gland morphology was significantly more diverse among male than among female Philanthinae. Conclusion: Our results show considerable variation in male head glands including the loss of an entire gland system and the evolution of a novel kind of secretory cells, confirming the prediction that interspecific diversity in head gland morphology is higher in male than in female Philanthini. We discuss possible causes for the remarkable evolutionary changes in males and we conclude that this high diversity has been caused by sexual selection

A cuckoo in wolves' clothing? Chemical mimicry in a specialized cuckoo wasp of the European beewolf (Hymenoptera, Chrysididae and Crabronidae)

<p>Abstract</p> <p>Background</p> <p>Host-parasite interactions are among the most important biotic relationships. Host species should evolve mechanisms to detect their enemies and employ appropriate counterstrategies. Parasites, in turn, should evolve mechanisms to evade detection and thus maximize their success. Females of the European beewolf (<it>Philanthus triangulum</it>, Hymenoptera, Crabronidae) hunt exclusively honeybee workers as food for their progeny. The brood cells containing the paralyzed bees are severely threatened by a highly specialized cuckoo wasp (<it>Hedychrum rutilans</it>, Hymenoptera, Chrysididae). Female cuckoo wasps enter beewolf nests to oviposit on paralyzed bees that are temporarily couched in the nest burrow. The cuckoo wasp larva kills the beewolf larva and feeds on it and the bees. Here, we investigated whether <it>H. rutilans </it>evades detection by its host. Since chemical senses are most important in the dark nest, we hypothesized that the cuckoo wasp might employ chemical camouflage.</p> <p>Results</p> <p>Field observations suggest that cuckoo wasps are attacked by beewolves in front of their nest, most probably after being recognized visually. In contrast, beewolves seem not to detect signs of the presence of these parasitoids neither when these had visited the nest nor when directly encountered in the dark nest burrow.</p> <p>In a recognition bioassay in observation cages, beewolf females responded significantly less frequently to filter paper discs treated with a cuticular extract from <it>H. rutilans </it>females, than to filter paper discs treated with an extract from another cuckoo wasp species (<it>Chrysis viridula</it>). The behavior to paper discs treated with a cuticular extract from <it>H. rutilans </it>females did not differ significantly from the behavior towards filter paper discs treated with the solvent only.</p> <p>We hypothesized that cuckoo wasps either mimic the chemistry of their beewolf host or their host's prey. We tested this hypothesis using GC-MS analyses of the cuticles of male and female beewolves, cuckoo wasps, and honeybee workers. Cuticle extracts of <it>Hedychrum nobile </it>(Hymenoptera: Chrysididae) and <it>Cerceris arenaria </it>(Hymenoptera: Crabronidae) were used as outgroups. There was little congruence with regard to cuticular compounds between <it>H. rutilans </it>females and honeybees as well as females of <it>C. arenaria </it>and <it>H. nobile</it>. However, there was a considerable similarity between beewolf females and <it>H. rutilans </it>females. Beewolf females show a striking dimorphism regarding their cuticular hydrocarbons with one morph having (<it>Z</it>)-9-C25:1 and the other morph having (<it>Z</it>)-9-C27:1 as the major component. <it>H. rutilans</it> females were more similar to the morph having (Z)-9-C27:1 as the main component.</p> <p>Conclusion</p> <p>We conclude that <it>H. rutilans </it>females closely mimic the composition of cuticular compounds of their host species <it>P. triangulum</it>. The occurrence of isomeric forms of certain compounds on the cuticles of the cuckoo wasps but their absence on beewolf females suggests that cuckoo wasps synthesize the cuticular compounds rather than sequester them from their host. Thus, the behavioral data and the chemical analysis provide evidence that a specialized cuckoo wasp exhibits chemical mimicry of the odor of its host. This probably allows the cuckoo wasp to enter the nest with a reduced risk of being detected by olfaction and without leaving traitorous chemical traces.</p

The Chemistry of the Postpharyngeal Gland of Female European Beewolves

Females of the European beewolf, Philanthus triangulum, possess a large glove-shaped gland in the head, the postpharyngeal gland (PPG). They apply the content of the PPG to their prey, paralyzed honeybees, where it delays fungal infestation. Here, we describe the chemical composition of the gland by using combined GC-MS, GC-FTIR, and derivatization. The PPG of beewolves contains mainly long-chain unsaturated hydrocarbons (C23–C33), lower amounts of saturated hydrocarbons (C14–C33), and minor amounts of methyl-branched hydrocarbons (C17–C31). Additionally, the hexane-soluble gland content is comprised of small amounts of an unsaturated C25 alcohol, an unknown sesquiterpene, an octadecenylmethylester, and several long-chain saturated (C25, C27) and unsaturated (C23–C27) ketones, some of which have not yet been reported as natural products. Surprisingly, we found a dimorphism with regard to the major component of the PPG with some females having (Z)-9-pentacosene, whereas others have (Z)-9-heptacosene as their predominant component. The biological relevance of the compounds for the prevention of fungal growth on the prey and the significance of the chemical dimorphism are discussed