19 research outputs found
Spherically symmetric dissipative anisotropic fluids: A general study
The full set of equations governing the evolution of self--gravitating
spherically symmetric dissipative fluids with anisotropic stresses is deployed
and used to carry out a general study on the behaviour of such systems, in the
context of general relativity. Emphasis is given to the link between the Weyl
tensor, the shear tensor, the anisotropy of the pressure and the density
inhomogeneity. In particular we provide the general, necessary and sufficient,
condition for the vanishing of the spatial gradients of energy density, which
in turn suggests a possible definition of a gravitational arrow of time. Some
solutions are also exhibited to illustrate the discussion.Comment: 28 pages Latex. To appear in Phys.Rev.
The Role of Radioactivities in Astrophysics
I present both a history of radioactivity in astrophysics and an introduction
to the major applications of radioactive abundances to astronomy
Extensive aortic valve ring abscess formation: a rare complication of Q fever endocarditis.
We report the successful management and 2 year follow up of a young patient with Q fever endocarditis on a congenitally bicuspid aortic valve complicated by extensive abscess formation in the aortic valve ring and interventricular septum. Aortic root abscess formation complicating Q fever endocarditis has been reported in only one previous patient. Serological tests may thus be indicated in patients with aortic abscesses. Despite extensive aortic and intramyocardial abscess formation it proved possible to control the progression of disease by open drainage of the abscess and aortic valve replacement. Although the requirement for aortic root replacement was anticipated in this patient, it has not been required