4,907 research outputs found

    High-resolution crystal structure of C-Phycocyanin and polarized optical spectra of single crystals

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    New Record of \u3ci\u3eBrachycercus Maculatus\u3c/i\u3e Berner (Ephemeroptera: Caenidae) From New York and a Key to Larvae of Northeastern Species

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    Brachycercus maculatus, a member of a rare group of mayflies, is now recorded for the first time from New York State in the upper Hudson River. An illustrated key to the Brachycercus larvae of northeastern North America is provided to spur further study of the genus in the region

    Super-Extremal Spinning Black Holes via Accretion

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    A Kerr black hole with mass MM and angular momentum JJ satisfies the extremality inequality ∣J∣≤M2|J| \le M^2. In the presence of matter and/or gravitational radiation, this bound needs to be reformulated in terms of local measurements of the mass and the angular momentum directly associated with the black hole. The isolated and dynamical horizon framework provides such quasi-local characterization of black hole mass and angular momentum. With this framework, it is possible in axisymmetry to reformulate the extremality limit as ∣J∣≤2 MH2|J| \le 2\,M_H^2, with MHM_H the irreducible mass of the black hole computed from its apparent horizon area and JJ obtained using approximate rotational Killing vectors on the apparent horizon. The ∣J∣≤2 MH2|J| \le 2\,M_H^2 condition is also equivalent to requiring a non-negative black hole surface gravity. We present numerical experiments of an accreting black hole that temporarily violates this extremality inequality. The initial configuration consists of a single, rotating black hole surrounded by a thick, shell cloud of negative energy density. For these numerical experiments, we introduce a new matter-without-matter evolution method.Comment: 11 pages, 10 figure

    ZZE-Configuration of chromophore ß-153 in C-phycocyanin from Mastigocladus laminosus

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    The photochemistry of C-phycocyanin has been studied after denaturation in the dark. It shows an irreversible reaction which has characteristics of a Ζ,Ζ,Ε- to Z,Z,Z-isomerization of dihydrobilins. Its amplitude depends on the reaction conditions, with a maximum corresponding to 15% conversion of one of the three PC chromophores. This chromophore is suggested to be ß-153, for which recent X-ray data T. Schirmer, W. Bode, and R. Huber, J. Mol. Biol., submitted, show ring D being highly twisted out of the plane of the other rings. During unfolding, there is thus a probability of falling into the photochemically labile Z,Z,^-configuration
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