4,907 research outputs found
New Record of \u3ci\u3eBrachycercus Maculatus\u3c/i\u3e Berner (Ephemeroptera: Caenidae) From New York and a Key to Larvae of Northeastern Species
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
A Kerr black hole with mass and angular momentum satisfies the
extremality inequality . 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 , with the irreducible mass of the black hole
computed from its apparent horizon area and obtained using approximate
rotational Killing vectors on the apparent horizon. The
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
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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