Black strings in (4+1)-dimensional Einstein-Yang-Mills theory

We study two classes of static uniform black string solutions in a (4+1)-dimensional SU(2) Einstein-Yang-Mills model. These configurations possess a regular event horizon and corresponds in a 4-dimensional picture to axially symmetric black hole solutions in an Einstein-Yang-Mills-Higgs-U(1)-dilaton theory. In this approach, one set of solutions possesses a nonzero magnetic charge, while the other solutions represent black holes located in between a monopole-antimonopole pair. A detailed analysis of the solutions' properties is presented, the domain of existence of the black strings being determined. New four dimensional solutions are found by boosting the five dimensional configurations. We also present an argument for the non-existence of finite mass hyperspherically symmetric black holes in SU(2) Einstein-Yang-Mills theory.Comment: 19 Revtex pages, 27 eps-figures; discussion on rotating black holes modifie

Non-uniqueness, Counterrotation, and Negative Horizon Mass of Einstein-Maxwell-Chern-Simons Black Holes

Stationary black holes in 5-dimensional Einstein-Maxwell-Chern-Simons theory possess surprising properties. When considering the Chern-Simons coefficient $\lambda$ as a parameter, two critical values of $\lambda$ appear: the supergravity value $\lambda_{\rm SG}=1$, and the value $\lambda=2$. At $\lambda=1$, supersymmetric black holes with vanishing horizon angular velocity, but finite angular momentum exist. As $\lambda$ increases beyond $\lambda_{\rm SG}$ a rotational instability arises, and counterrotating black holes appear, whose horizon rotates in the opposite sense to the angular momentum. Thus supersymmetry is associated with the borderline between stability and instability. At $\lambda=2$ rotating black holes with vanishing angular momentum emerge. Beyond $\lambda=2$ black holes may possess a negative horizon mass, while their total mass is positive. Charged rotating black holes with vanishing gyromagnetic ratio appear, and black holes are no longer uniquely characterized by their global charges.Comment: 15 pages, 16 figures, MPLA style, invited review for Modern Physics Letters

Rotating Boson Stars and Q-Balls

We consider axially symmetric, rotating boson stars. Their flat space limits represent spinning Q-balls. We discuss their properties and determine their domain of existence. Q-balls and boson stars are stationary solutions and exist only in a limited frequency range. The coupling to gravity gives rise to a spiral-like frequency dependence of the boson stars. We address the flat space limit and the limit of strong gravitational coupling. For comparison we also determine the properties of spherically symmetric Q-balls and boson stars.Comment: 22 pages, 18 figure

Solid rocket technology advancements for space tug and IUS applications

In order for the shuttle tug or interim upper stage (IUS) to capture all the missions in the current mission model for the tug and the IUS, an auxiliary or kick stage, using a solid propellant rocket motor, is required. Two solid propellant rocket motor technology concepts are described. One concept, called the 'advanced propulsion module' motor, is an 1800-kg, high-mass-fraction motor, which is single-burn and contains Class 2 propellent. The other concept, called the high energy upper stage restartable solid, is a two-burn (stop-restartable on command) motor which at present contains 1400 kg of Class 7 propellant. The details and status of the motor design and component and motor test results to date are presented, along with the schedule for future work

A parallelizable GMRES-type method for p-cyclic matrices, with applications in circuit simulation

In this paper we propose a GMRES-type method for the solution of linear systems with a p-cyclic coecient matrix. These p-cyclic matrices arise in the periodic steady state simulation of circuits, assuming that the DAE is discretized in the time domain. The method has similarities with existing GMRES approaches for p-cyclic matrices, but in contrast to these methods the method is eciently parallelizable, even if the p-cyclic matrix has a small block size. However, the serial costs of the method may be somewhat higher. Numerical experiments demonstrate the eectiveness of the method

Einstein-Yang-Mills solutions in higher dimensional de Sitter spacetime

We consider particle-like and black holes solutions of the Einstein-Yang-Mills system with positive cosmological constant in d>4 spacetime dimensions. These configurations are spherically symmetric and present a cosmological horizon for a finite value of the radial coordinate, approaching asymptotically the de Sitter background. In the usual Yang--Mills case we find that the mass of these solutions, evaluated outside the cosmological horizon at future/past infinity generically diverges for d>4. Solutions with finite mass are found by adding to the action higher order gauge field terms belonging to the Yang--Mills hierarchy. A discussion of the main properties of these solutions and their differences from those to the usual Yang-Mills model, both in four and higher dimensions is presented.Comment: 17 pages, 8 figure

Does the Presence of a Measurable Blood Alcohol Level in a Potential Organ Donor Affect the Outcome of Liver Transplantation?

The widespread application of hepatic transplantation has created a tremendous demand for donor organs. An assessment of donor parameters is thought to be important in selecting good donors; however, the criteria utilized have not been standardized. This study was performed to determine the effect of a measurable donor blood alcohol level on graft survival. Fifty‐two patients who underwent orthotopic liver transplantation at the University of Pittsburgh were included in the study. Twenty‐five patients received liver grafts from donors having a blood alcohol level between 0.04 and 0.4 g/I with a mean of 0.17 g/I. Twenty‐seven patients received a liver graft from a donor who had no measurable blood alcohol. There were no differences between these two groups of donors regarding the time of initial hospitalization until the time of donation. Graft failure within the first 30 days was 24% for those receiving an organ from an alcohol‐positive donor as compared with 22.2% in those receiving an organ from an alcohol negative donor. The recipient mortality rate was 16% and 11%, respectively. No relationships between the donor blood alcohol level and organ performance, frequency of primary graft nonfunction, or number of episodes of acute cellular rejection were evident. Based upon these data, the presence of a measurable blood alcohol level in a donor should not mitigate against organ donation. Copyright © 1991, Wiley Blackwell. All rights reserve

Fast iterative solution of reaction-diffusion control problems arising from chemical processes

PDE-constrained optimization problems, and the development of preconditioned iterative methods for the efficient solution of the arising matrix system, is a field of numerical analysis that has recently been attracting much attention. In this paper, we analyze and develop preconditioners for matrix systems that arise from the optimal control of reaction-diffusion equations, which themselves result from chemical processes. Important aspects in our solvers are saddle point theory, mass matrix representation and effective Schur complement approximation, as well as the outer (Newton) iteration to take account of the nonlinearity of the underlying PDEs