27 research outputs found
A Charged Rotating Black Ring
We construct a supergravity solution describing a charged rotating black ring
with S^2xS^1 horizon in a five dimensional asymptotically flat spacetime. In
the neutral limit the solution is the rotating black ring recently found by
Emparan and Reall. We determine the exact value of the lower bound on J^2/M^3,
where J is the angular momentum and M the mass; the black ring saturating this
bound has maximum entropy for the given mass. The charged black ring is
characterized by mass M, angular momentum J, and electric charge Q, and it also
carries local fundamental string charge. The electric charge distributed
uniformly along the ring helps support the ring against its gravitational
self-attraction, so that J^2/M^3 can be made arbitrarily small while Q/M
remains finite. The charged black ring has an extremal limit in which the
horizon coincides with the singularity.Comment: 25 pages, 1 figur
Type IIB Solutions with Interpolating Supersymmetries
We study type IIB supergravity solutions with four supersymmetries that
interpolate between two types widely considered in the literature: the dual of
Becker and Becker's compactifications of M-theory to 3 dimensions and the dual
of Strominger's torsion compactifications of heterotic theory to 4 dimensions.
We find that for all intermediate solutions the internal manifold is not
Calabi-Yau, but has SU(3) holonomy in a connection with a torsion given by the
3-form flux. All 3-form and 5-form fluxes, as well as the dilaton, depend on
one function appearing in the supersymmetry spinor, which satisfies a nonlinear
differential equation. We check that the fields corresponding to a flat bound
state of D3/D5-branes lie in our class of solutions. The relations among
supergravity fields that we derive should be useful in studying new gravity
duals of gauge theories, as well as possibly compactifications.Comment: 27pp, v2 REVTeX4, typographical fixes and minor clarifications, v3
added ref, modified discussion of RR axion slightl
A model to study intestinal and hepatic metabolism of propranolol in the dog
A model to investigate hepatic drug uptake and metabolism in the dog was developed for this study. Catheters were placed in the portal and hepatic veins during exploratory laparotomy to collect pre- and posthepatic blood samples at defined intervals. Drug concentrations in the portal vein were taken to reflect intestinal uptake and metabolism of an p.o. administered drug (propranolol), while differences in drug and metabolite concentrations between portal and hepatic veins reflected hepatic uptake and metabolism. A significant difference in propranolol concentration between hepatic and portal veins confirmed a high hepatic extraction of this therapeutic agent in the dog. This technically uncomplicated model may be used experimentally or clinically to determine hepatic function and metabolism of drugs that may be administered during anaesthesia and surgery