Forgotten feathers
نویسندگان
چکیده
منابع مشابه
Unzipping bird feathers.
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...
متن کاملThickness of Feathers
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...
متن کاملAxioms for Thickness of Feathers
We approach thickness of feathers from an axiomatic point of view. We show that our axioms are independent and we use our axioms to establish general properties for arbitrary definitions of thickness which satisfy these axioms. 1. Axioms for Thickness Informally, a feather is a semigroup derivation diagram with the labels on the edges removed. See [2] for a discussion of semigroup derivation di...
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The flight feathers and their coverts of a European kestrel Falco tinnunculus have been tested for their air transmissivity. The transmissivity was measured in both directions, i.e. from ventral to dorsal and vice versa; the mean difference between the two directions was less than 10 %. However, the transmissivity of the inner versus outer vanes of the remiges and coverts differed significantly...
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This is a most worth-while volume, that should be read by social workers in particular and humanitarians in general. Within small bulk, it lays bare, without offence to those who are labouring now in this field, the great need of the inhabitants of Common Lodging Houses, to be understood in the first place, and to be given the help they so sorely need, in the second. The survey is well planned,...
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ژورنال
عنوان ژورنال: Emu
سال: 1901
ISSN: 0158-4197
DOI: 10.1071/mu901070