A positive theory of income distribution based on assumptions concerning the supply of and demand for each type of productive service is presented. The demand function of the organizers of production may be derived from the maximization of profits with the income scale and the production function as restrictions. A normative theory based on the maximization of a social utility or welfare function is also considered. In the normative theory, production functions and balance equations (some representing compartmentalization of factor markets) are introduced as restrictions and again an income scale results, this time maximizing social welfare. Empirical testing is also considered. The positive theory was developed in part to take into consideration the fact that personal income distributions can reasonably well be described by log normal distributions, and that skill parameters are often normally distributed. Limited testing of the influence of wealth, intelligence, education, and sex suggest that these account for only a small part of the variance in the income distribution. This suggests the need for further research.
The common kingfisher, A. atthis, has an orange breast, a mostly cyan back (mantle) and a blue tail; the wings and head have a mix of blue and blue-green feather patches (Fig.1A). The feathers strongly overlap (Fig.1B), and all three main feather types (orange, Accepted 5 September 2011 SUMMARY The colours of the common kingfisher, Alcedo atthis, reside in the barbs of the three main types of feather: the orange breast feathers, the cyan back feathers and the blue tail feathers. Scanning electron microscopy showed that the orange barbs contain small pigment granules. The cyan and blue barbs contain spongy nanostructures with slightly different dimensions, causing different reflectance spectra. Imaging scatterometry showed that the pigmented barbs create a diffuse orange scattering and the spongy barb structures create iridescence. The extent of the angle-dependent light scattering increases with decreasing wavelength. All barbs have a cortical envelope with a thickness of a few micrometres. The reflectance spectra of the cortex of the barbs show oscillations when measured from small areas, but when measured from larger areas the spectra become wavelength independent. This can be directly understood with thin film modelling, assuming a somewhat variable cortex thickness. The cortex reflectance appears to be small but not negligible with respect to the pigmentary and structural barb reflectance.
SUMMARYThe feathers of Amazon parrots are brightly coloured. They contain a unique class of pigments, the psittacofulvins, deposited in both barbs and barbules, causing yellow or red coloured feathers. In specific feather areas, spongy nanostructured barb cells exist, reflecting either in the blue or blue-green wavelength range. The blue-green spongy structures are partly enveloped by a blue-absorbing, yellow-colouring pigment acting as a spectral filter, thus yielding a green coloured barb. Applying reflection and transmission spectroscopy, we characterized the Amazons' pigments and spongy structures, and investigated how they contribute to the feather coloration. The reflectance spectra of Amazon feathers are presumably tuned to the sensitivity spectra of the visual photoreceptors.Supplementary material available online at
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