Understanding temporal changes in contaminant levels in coastal environments requires comparing levels of contaminants from the same species from different time periods, particularly if species are declining. Several species of shorebirds migrating through Delaware Bay have declined from the 1980s to the present. To evaluate some contaminants as cause for the declines, we examine levels of merc...

Asymmetrical feathers have been associated with flight capability but are also found in species that do not fly, and their appearance was a major event in feather evolution. Among non-avialan theropods, they are only known in microraptorine dromaeosaurids. Here we report a new troodontid, Jianianhualong tengi gen. et sp. nov., from the Lower Cretaceous Jehol Group of China, that has anatomical ...

Nonuniform exposures often affect imaging systems, e.g., owing to vignetting. Moreover, the sensor's radiometric response may be nonlinear. These characteristics hinder photometric measurements. They are particularly annoying in image mosaicking, in which images are stitched to enhance the field of view. Mosaics suffer from seams stemming from radiometric inconsistencies between raw images. Pri...

We measured the polarization- and angle-resolved optical scattering and reflection spectra of the quasiordered nanostructures in the bird feather barbs. In addition to the primary peak that originates from single scattering, we observed a secondary peak which exhibits depolarization and distinct angular dispersion. We explained the secondary peak in terms of double scattering, i.e., light is sc...

The bird feather vane can be separated into two parts by pulling the barbs apart. The original state can be re-established easily by lightly stroking through the feather. Hooklets responsible for holding vane barbs together are not damaged by multiple zipping and unzipping cycles. Because numerous microhooks keep the integrity of the feather, their properties are of great interest for understan...

Briefly, a feather is a semigroup derivation diagram with the labels on the edges removed. In this paper, we are concerned with possible definitions for the thickness of a feather. A major open problem is whether the word problem is solvable for semigroup presentations with one defining relation. It is known that word problems for semigroup presentations are solvable if the number of regions in...

Feathers are under-represented in the fossil record because soft tissues do not usually preserve well sedimentary sequences. Fossil feathers nevertheless extremely important resolving pattern and process related to origin of dinosaur flight. In recent years, a number have been discovered which mummified amber; these preserved three dimensions with remarkable sub-microscopic details especially f...

The identification of bird species from feather fragments is useful in many disciplines, including forensic science. Feather evidence can be helpful to criminal investigations in demonstrating physical contact between clothing manufactured with down feathers, or it may provide specific links to the crime scene by identifying the species or group of birds from which the feather evidence came. Th...

We report the mechanism of color production in peacock feathers. We find that the cortex in differently colored barbules, which contains a 2D photonic-crystal structure, is responsible for coloration. Simulations reveal that the photonic-crystal structure possesses a partial photonic bandgap along the direction normal to the cortex surface, for frequencies within which light is strongly reflect...

Proteases are catabolic enzymes that catalyze the complete hydrolysis of protein. They constitute one of the most important groups of industrial enzymes, accounting for nearly 60% of the total worldwide enzyme sale1. Keratinolytic protease is a specific protease that has immense commercial importance. It acts on keratin of the hides thus can be used in dehairing2. This enzyme along with proteas...