Identification of the Sex Pheromone of the Currant Shoot Borer Lampronia capitella

Under an artificial light:dark cycle, females of Lampronia capitella were observed calling, with extended terminal abdominal segments, during the first 2 hr of the photoperiod. Extracts of terminal abdominal segments from females elicited large electroantennographic responses from male antennae. Gas chromatography with electroantennographic detection revealed three active peaks. Based on comparison of retention times and mass spectra of synthetic standards, these compounds were identified as (Z,Z)-9,11-tetradecadienol and the corresponding acetate and aldehyde. The electroantennographic activity of the four geometric isomers of all three compounds was investigated, and the respective (Z,Z)-isomer was found to be the most active in all cases. Aldehydes generally elicited larger antennal responses than alcohols, whereas acetates were the least active compounds. A subtractive trapping assay in the field, based on a 13:26:100 micrograms mixture of (Z,Z)-9,11-tetradecadienal, (Z,Z)-9,11-tetradecadienyl acetate, and (Z,Z)-9,11-tetradecadienol confirmed that all three compounds are pheromone components. Subtraction of (Z,Z)-9,11-tetradecadienol from the blend completely eliminated its attractiveness, whereas the other two-component blends showed reduced activity. This is the first pheromone identification from the monotrysian superfamily Incurvarioidea, confirming that the common pheromones among ditrysian moths (long-chain fatty acid derivatives comprising alcohols, acetates, and aldehydes with one or more double bonds) is not an autapomorphy of Ditrysia, but a synapomorphy of the more advanced heteroneuran lineages.     

Acquired and Partially De Novo Synthesized Pyrrolizidine Alkaloids in Two Polyphagous Arctiids and the Alkaloid Profiles of Their Larval Food-Plants

The profiles of pyrrolizidine alkaloids (PAs) in the two highly polyphagous arctiids Estigmene acrea and Grammia geneura and their potential PA sources in southeastern Arizona were compiled. One of four species of Boraginaceae, Plagiobothrys arizonicus, contained PAs; this is the first PA record for this plant species. The principle PA sources are Senecio longilobus (Asteraceae) and Crotalaria pumila (Fabaceae). The known PA pattern of S. longilobus was extended; the species was found to contain six closely related PAs of the senecionine type. Three novel PAs of the monocrotaline type, named pumilines A-C, were isolated and characterized from C. pumila, a species not studied before. The pumilines are the major PAs in the seeds, while in the vegetative organs they are accompanied by the simple necine derivatives supinidine and as the dominant compound subulacine (1beta,2beta-epoxytrachelanthamidine). In both plant species, the PAs are stored as N-oxides, except C. pumila seeds, which accumulate the free bases. Great variation in PA composition was observed between local populations of C. pumila. The PA profiles were established for larvae and adults of E. acrea that as larvae had fed on an artificial diet supplemented with crotalaria-powder and of G. geneura fed with S. longilobus. In both experiments, the larvae had a free choice between the respective PA source and diet or food plants free of PAs. The profiles compiled for the two species reflect the alkaloid profiles of their PA sources with one exception, subulacine could never be detected in E. acrea. Besides acquired PAs, insect PAs synthesized from acquired necine bases and necic acids of insect origin were detected in the two arctiid species. These insect PAs that do not occur in the larval food sources accounted for some 40-70% (E. acrea) and 17-37% (G. geneura) of total PAs extracted from the insects. A number of novel insect PAs were identified. Plant-acquired and insect PAs were found to accumulate as N-oxides. The results are discussed in relation to specific biochemical, electrophysiological, and behavioral mechanisms involved in PA sequestration by arctiids.     

Improving generalization capabilities of dynamic neural networks

This work addresses the problem of improving the generalization capabilities of continuous recurrent neural networks. The learning task is transformed into an optimal control framework in which the weights and the initial network state are treated as unknown controls. A new learning algorithm based on a variational formulation of Pontrayagin's maximum principle is proposed. Under reasonable assumptions, its convergence is discussed. Numerical examples are given that demonstrate an essential improvement of generalization capabilities after the learning process of a dynamic network.     

Two software tools for plane-wave scattering on nonspherical particles in the German Aerospace Center's Virtual Laboratory

We present the methodological background, the range of applicability, and the on-line usage of two software packages, MIESCHKA and CYL, which we have developed for light-scattering analysis on nonspherical particles. MIESCHKA solves Maxwell's equations in a rigorous way but is restricted to axisymmetric geometries, whereas CYL is an approximation for finite columns with nonspherical cross sections. We have established an easy on-line access to both of these programs through the Virtual Laboratory. Its generic software infrastructure was designed to simplify the web-based usage and to support the intercomparability of scientific software.     

Holzinger, A.: Basiswissen Multimedia Bd. 1: Technik. Zahlir Abb., 284 S. ISBN 3-8023-1856-0; Bd. 2: Lernen. Zahlr. Abb., 290 S. ISBN 3-8023-1857-0; Bd. 3: Design. Zahlr. Abb., 280 S. ISBN 3-8023-1858-0. Vogl, Würzburg, 2000. DM 59,-, ATS 431,- (je Band)

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Holzinger, A.: Basiswissen Multimedia Bd. 1: Technik. Zahlir Abb., 284 S. ISBN 3-8023-1856-0; Bd. 2: Lernen. Zahlr. Abb., 290 S. ISBN 3-8023-1857-0; Bd. 3: Design. Zahlr. Abb., 280 S. ISBN 3-8023-1858-0. Vogl, Würzburg, 2000. DM 59,-, ATS 431,- (je Band)     

Multisensory recognition of actively explored objects.

Shape recognition can be achieved through vision or touch, raising the issue of how this information is shared across modalities. Here we provide a short review of previous findings on cross-modal object recognition and we provide new empirical data on multisensory recognition of actively explored objects. It was previously shown that, similar to vision, haptic recognition of objects fixed in space is orientation specific and that cross-modal object recognition performance was relatively efficient when these views of the objects were matched across the sensory modalities (Newell, Ernst, Tjan, & Bülthoff, 2001). For actively explored (i.e., spatially unconstrained) objects, we now found a cost in cross-modal relative to within-modal recognition performance. At first, this may seem to be in contrast to findings by Newell et al. (2001). However, a detailed video analysis of the visual and haptic exploration behaviour during learning and recognition revealed that one view of the objects was predominantly explored relative to all others. Thus, active visual and haptic exploration is not balanced across object views. The cost in recognition performance across modalities for actively explored objects could be attributed to the fact that the predominantly learned object view was not appropriately matched between learning and recognition test in the cross-modal conditions. Thus, it seems that participants naturally adopt an exploration strategy during visual and haptic object learning that involves constraining the orientation of the objects. Although this strategy ensures good within-modal performance, it is not optimal for achieving the best recognition performance across modalities. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Auftraglöten zum Verschleißschutz von Titanwerkstoffen

Wear Protection of Titanium using Surface Brazing Titanium and titanium alloys possess high specific strengths up to a temperature of about 600 °C in addition to an extraordinary corrosion resistance [1]. The low wear resistance constitutes a crucial impediment for a much broader use. Titanium materials are especially susceptible to friction fatigue and erosion. Coating techniques have to be developed in order to counteract this technical constraint. Surface brazing presents a promising approach. Hard metals mixed with brazing filler metals on a silver and titanium basis were brazed in a vacuum furnace and subsequently characterized. Wear resistance was quantified and optimized using ball on disc measurements.