منابع مشابه
Ribozymes: Red in tooth and claw
A population of catalytic RNA molecules has been engineered to operate and evolve in vitro in a continuous manner. The novel continuity of the process allows the propagation of many generations in a very short time and without the manual manipulation necessary with traditional in vitro selection techniques.
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The vertebrate ectoderm gives rise to organs that produce mineralized or keratinized substances, including teeth, hair, and claws. Most of these ectodermal derivatives grow continuously throughout the animal׳s life and have active pools of adult stem cells that generate all the necessary cell types. These organs provide powerful systems for understanding the mechanisms that enable stem cells to...
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We conjecture that, for each tree T , there exists a natural number kT such that the following holds: If G is a kT -edge-connected graph such that |E(T )| divides |E(G)|, then the edges of G can be divided into parts, each of which is isomorphic to T . We prove that for T = K1,3 (the claw), this holds if and only if there exists a (smallest) natural number kt such that every kt-edge-connected g...
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In this paper we prove that if G is a connected claw-free graph with three pairwise non-adjacent vertices, with chromatic number χ and clique number ω, then χ ≤ 2ω and the same for the complement of G. We also prove that the choice number of G is at most 2ω, except possibly in the case when G can be obtained from a subgraph of the Schläfli graph by replicating vertices. Finally, we show that th...
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ژورنال
عنوان ژورنال: BioScience
سال: 2006
ISSN: 0006-3568
DOI: 10.1641/0006-3568(2006)056[0446:tac]2.0.co;2