Surface lipids of the social waspPolistes annularis (L.) and its nest and nest pedicel

Cuticular lipids were recovered fromPolistes annularis workers and characterized by combined gas-chromatography-mass spectrometry. These lipids were found to be straight-chain and methyl-branched hydrocarbons with the major components being 13,17-dimethylhentriacontane (18%), 3-methyl-nonacosane (13%), and 3-methylheptacosane (11%). Cuticular lipids with a very similar composition were found on the surface of the larvae, eggs, and adult males ofPolistes annularis as well as on the surface of the nest and nest pedicel of the wasp. Hexadecanoic acid and octadecenoic acid were also found on the surface of the nest pedicel and these acids and/or the hydrocarbons may play a defensive role for the wasps.     

Luft

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Butter, Speisefette und ?le

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Fractal image compression with region-based functionality

Region-based functionality offered by the MPEG-4 video compression standard is also appealing for still images, for example to permit object-based queries of a still-image database. A popular method for still-image compression is fractal coding. However, traditional fractal image coding uses rectangular range and domain blocks. Although new schemes have been proposed that merge small blocks into irregular shapes, the merging process does not, in general, produce semantically-meaningful regions. We propose a new approach to fractal image coding that permits region-based functionalities; images are coded region by region according to a previously-computed segmentation map. We use rectangular range and domain blocks, but divide boundary blocks into segments belonging to different regions. Since this prevents the use of standard dissimilarity measure, we propose a new measure adapted to segment shape. We propose two approaches: one in the spatial and one in the transform domain. While providing additional functionality, the proposed methods perform similarly to other tested methods in terms of PSNR but often result in images that are subjectively better. Due to the limited domain-block codebook size, the new methods are faster than other fractal coding methods tested. The results are very encouraging and show the potential of this approach for various internet and still-image database applications.     

Galerkin's method and the variational procedure

Galerkin's method and the variational procedure, when applied to most practical problems in electromagnetics, lead to matrix equations of the same form. Variational procedures for self-adjoint and nonself-adjoint operators also result in the same form of matrix equations for a large subclass of problems. However, the three cases may yield different matrix equations in general. This paper examines the subclass of problems for which these methods result in the same matrix equation and provides systematic ways for classification of problems for which two or all three of the cases lead to the same matrix equation. It also describes properties of the coefficient matrix in the matrix equation