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The Gram-negative bacterium Flavobacterium sp. strain R1534 is a natural producer of zeaxanthin. A 14 kb genomic DNA fragment of this organism has been cloned and a 5.1 kb piece containing the carotenoid biosynthesis genes sequenced. The carotenoid biosynthesis cluster consists of five genes arranged in at least two operons. The five genes are necessary and(More)
Ultraviolet B (UVB, 290-320 nm) radiation initiates in vivo a dose- and wavelength-dependent down regulation of cell-mediated immunity. An action spectrum for UV-induced immunosuppression indicated that the photoreceptor for this effect is urocanic acid (UCA), which undergoes a trans to cis isomerization in the stratum corneum on UV exposure. An(More)
It is proved that the shape of the typical cell of a Delaunay tessellation, derived from a stationary Poisson point process in d-dimensional Euclidean space, tends to the shape of a regular simplex, given that the volume of the typical cell tends to infinity. This follows from an estimate for the probability that the typical cell deviates by a given amount(More)
For a non-empty compact set A ⊂ R , d ≥ 2, and r ≥ 0, let A⊕r denote the set of points whose distance fromA is r at the most. It is well-known that the volume,Vd(A⊕r ), ofA⊕r is a polynomial of degree d in the parameter r if A is convex. We pursue the reverse question and ask whether A is necessarily convex if Vd(A⊕r ) is a polynomial in r . An affirmative(More)