The evolution of bilaterally symmetric feathers is a fundamental process leading toward flight. One major unsolved mystery is how the feathers of a single bird can form radially symmetric downy feathers and bilaterally symmetric flight feathers. In developing downy feather follicles, barb ridges are organized parallel to the long axis of the feather follicle. In developing flight-feather follic...

Melanin has been associated with increased resistance to abrasion, decreased wear and lowered barb breakage in feathers. But, this association was inferred without considering barb position along the rachis as a potentially confounding variable. We examined the cross-sectional area, breaking force, breaking stress, breaking strain and toughness of melanized and unmelanized barbs along the entir...

Shark-fin soup has gotten a bad rap since conservation groups began raising awareness of shark finning, a practice in which fishermen slice the fins off the animals, sometimes while they are still alive, and discard the bodies overboard. Now, scientists have found another reason to avoid the Asian delicacy: it may be detrimental to neurologic health. Worldwide, an estimated 26–73 million sharks...

A. Reduction-closed barbed congruence (Section II) Definition 28 (Reduction-closed barbed congruence). Let L be a process calculus, in which a reduction relation −→L and barb predicates ↓a , for each a in a given set of names, have been defined. A relationR on the processes of L is context-closed if PRQ implies C[P ]RC[Q], for each context C of L; the relation is barb-preserving if for any name...

The levels of the flavanones naringin, hesperidin, narirutin, eriocitrin, neohesperidin and neoeriocitrin, and the flavone diosmin were evaluated in fruits of several exotic citrus (citron, pummelo, sour orange, papeda, mandarin and lemon). The highest total flavonoid content was detected in sour oranges and mandarins, while low to non-detectable levels were found in pummelo, papeda, citron, an...

The development and reproduction of the citrus leafminer (CLM), Phyllocnistis citrella Stainton, were evaluated in six citrus genotypes in order to identify genotypes with resistance traits that could be applied in a program for the development of citrus varieties resistant to the citrus leafminer. Tests were conducted under controlled laboratory conditions (25 ± 1ºC, 70 ± 10% RH, and 14h photo...

We study a dynamic, decentralized lemons market with one–time entry and characterize its set of non–stationary equilibria. This framework offers a theory of how a market suffering from adverse selection recovers over time endogenously; given an initial fraction of lemons, the model provides sharp predictions about how prices and the composition of assets evolve over time. Comparing economies in...

Layoffs, Lemons, Race and Gender This paper expands on Gibbons and Katz (1991) by looking at how the difference in wage losses across plant closing and layoff varies with race and gender. We find that the differences between white males and the other groups are striking and complex. The lemons effect of layoff holds for white males as in Gibbons and Katz model, but not for the other three demog...

Asymmetry in flight feather vane width is a major functional innovation associated with the evolution of flight in the ancestors of birds. However, the developmental and morphological basis of feather shape is not simple, and the developmental processes involved in vane width asymmetry are poorly understood. We present a theoretical model of feather morphology and development that describes the...

BarA of Streptomyces virginiae is a specific receptor protein for a member of butyrolactone autoregulators which binds to an upstream region of target genes to control transcription, leading to the production of the antibiotic virginiamycin M(1) and S. BarA-binding DNA sequences (BarA-responsive elements [BAREs]), to which BarA binds for transcriptional control, were restricted to 26 to 29-nucl...