Gravitational waves from quasi-spherical black holes

A quasi-spherical approximation scheme, intended to apply to coalescing black holes, allows the waveforms of gravitational radiation to be computed by integrating ordinary differential equations.Comment: 4 revtex pages, 2 eps figure

Gravitational Waves from a Fissioning White Hole

We present a fully nonlinear calculation of the waveform of the gravitational radiation emitted in the fission of a vacuum white hole. At early times, the waveforms agree with close-approximation perturbative calculations but they reveal dramatic time and angular dependence in the nonlinear regime. The results pave the way for a subsequent computation of the radiation emitted after a binary black hole merger.Comment: 11 pages, 6 figures, RevTeX

Complete null data for a black hole collision

We present an algorithm for calculating the complete data on an event horizon which constitute the necessary input for characteristic evolution of the exterior spacetime. We apply this algorithm to study the intrinsic and extrinsic geometry of a binary black hole event horizon, constructing a sequence of binary black hole event horizons which approaches a single Schwarzschild black hole horizon as a limiting case. The linear perturbation of the Schwarzschild horizon provides global insight into the close limit for binary black holes, in which the individual holes have joined in the infinite past. In general there is a division of the horizon into interior and exterior regions, analogous to the division of the Schwarzschild horizon by the r=2M bifurcation sphere. In passing from the perturbative to the strongly nonlinear regime there is a transition in which the individual black holes persist in the exterior portion of the horizon. The algorithm is intended to provide the data sets for production of a catalog of nonlinear post-merger wave forms using the PITT null code.Comment: Revised version, to appear in Phys. Rev. D. July 15 (2001), 41 pages, 11 figures, RevTeX/epsf/psfi

Mode coupling in the nonlinear response of black holes

We study the properties of the outgoing gravitational wave produced when a non-spinning black hole is excited by an ingoing gravitational wave. Simulations using a numerical code for solving Einstein's equations allow the study to be extended from the linearized approximation, where the system is treated as a perturbed Schwarzschild black hole, to the fully nonlinear regime. Several nonlinear features are found which bear importance to the data analysis of gravitational waves. When compared to the results obtained in the linearized approximation, we observe large phase shifts, a stronger than linear generation of gravitational wave output and considerable generation of radiation in polarization states which are not found in the linearized approximation. In terms of a spherical harmonic decomposition, the nonlinear properties of the harmonic amplitudes have simple scaling properties which offer an economical way to catalog the details of the waves produced in such black hole processes.Comment: 17 pages, 20 figures, abstract and introduction re-writte

The formation of planetary disks and winds: an ultraviolet view

Planetary systems are angular momentum reservoirs generated during star formation. This accretion process produces very powerful engines able to drive the optical jets and the molecular outflows. A fraction of the engine energy is released into heating thus the temperature of the engine ranges from the 3000K of the inner disk material to the 10MK in the areas where magnetic reconnection occurs. There are important unsolved problems concerning the nature of the engine, its evolution and the impact of the engine in the chemical evolution of the inner disk. Of special relevance is the understanding of the shear layer between the stellar photosphere and the disk; this layer controls a significant fraction of the magnetic field building up and the subsequent dissipative processes ougth to be studied in the UV. This contribution focus on describing the connections between 1 Myr old suns and the Sun and the requirements for new UV instrumentation to address their evolution during this period. Two types of observations are shown to be needed: monitoring programmes and high resolution imaging down to, at least, milliarsecond scales.Comment: Accepted for publication in Astrophysics and Space Science 9 figure

Cómo se viven los derechos reproductivos en Ecuador: escenarios, contextos y circunstancias

La Comisión de Transición hacia el Consejo de las Mujeres y la Igualdad de Género es el mecanismo especializado del Estado, cuyo mandato es la definición de la institucionalidad pública que garantice la igualdad entre hombres y mujeres. Para su cumplimiento el Directorio de la Comisión una vez instalado, definió como objetivos estratégicos que guiaron la gestión institucional, los siguientes: 1. Impulsar un Sistema de Igualdad entre mujeres y hombres, que fortalezca al Estado democrático para el Buen Vivir. 2. Incidir en los Sistemas de Participación Pública y Política para lograr la autonomía política y toma de decisiones de las mujeres. 3. Incidir en la construcción de un Sistema de Justicia y de Protección de derechos que permita la Autonomía de las mujeres. 4. Incidir en la construcción de un Sistema económico social y solidario que garantice la autonomía económica de las mujeres. Uno de los temas enfatizados para la consecución del Objetivo 3 fue la contratación de varios estudios sobre la problemática de la salud sexual y reproductiva de las mujeres. En este marco presenta la recopilación de tres estudios sobre la problemática del aborto abordada desde diferentes entradas que se consideran insumos estratégicos para la construcción de política pública. La actual coyuntura política del país, en la que se debaten leyes que podrían ampliar el ejercicio de los derechos reproductivos de las mujeres o restringirlos más todavía, constituye el escenario propicio para la presentación de esta publicación que se confía, servirá para reafirmar derechos o desechar información incorrecta y prejuicios que sobre la temática existen en el imaginario social ecuatoriano. Se espera que este aporte guíe hacia un cambio legislativo que garantice a las mujeres su derecho a decidir y optar legalmente por continuar o interrumpir sus maternidades, en concordancia con sus deseos y circunstancias personales. Comisión de Transición hacia el Consejo de las Mujeres y la Igualdad de Género.COMISIÓN DE TRANSICIÓN HACIA EL CONSEJO DE LAS MUJERES Y LA IGUALDAD DE GÉNER

Bondian frames to couple matter with radiation

A study is presented for the non linear evolution of a self gravitating distribution of matter coupled to a massless scalar field. The characteristic formulation for numerical relativity is used to follow the evolution by a sequence of light cones open to the future. Bondian frames are used to endow physical meaning to the matter variables and to the massless scalar field. Asymptotic approaches to the origin and to infinity are achieved; at the boundary surface interior and exterior solutions are matched guaranteeing the Darmois--Lichnerowicz conditions. To show how the scheme works some numerical models are discussed. We exemplify evolving scalar waves on the following fixed backgrounds: A) an atmosphere between the boundary surface of an incompressible mixtured fluid and infinity; B) a polytropic distribution matched to a Schwarzschild exterior; C) a Schwarzschild- Schwarzschild spacetime. The conservation of energy, the Newman--Penrose constant preservation and other expected features are observed.Comment: 20 pages, 6 figures; to appear in General Relativity and Gravitatio

Design of a continuous production energy machine from marine trochoidal waves

This paper describes the development of a continuous production energy machine from marine trochoidal waves. Studying the characteristics of trochoidal waves in a geographical area near Cartagena, we have developed a device, which taking advantage of the marine surface oscillation in order to produce the movement of a mechanical device, is able to transforming the mechanical energy into electrical energy.Peer Reviewe

Modelization of a hybrid system with renewable energy for electric propulsion in boats. Application to a robotic floating platform

A model of a hybrid system with renewable energy for electric propulsion in boats in which energy generated by photovoltaic panels and hydrogenerator is stored in the main battery which exerts its function as central element of a renewable cycle is presented. Additionally, hydrogen plays a role being generated by an electrolyzer for later to be stored in cylinders aboard in order to generate electric power by a fuel cell. Both, batteries and cylinders can be used to feed the different elements of the system, more specially the thruster while the excess of power is stored in another battery which is auxiliary and it is able to feed the first when it is necessary.Peer Reviewe

Amplification of evanescent waves in a lossy left-handed material slab

We carry out finite-difference time-domain (FDTD) simulations, with a specially-designed boundary condition, on pure evanescent waves interacting with a lossy left-handed material (LHM) slab. Our results provide the first full-wave numerical evidence for the amplification of evanescent waves inside a LHM slab of finite absorption. The amplification is due to the interactions between the evanescent waves and the coupled surface polaritons at the two surfaces of the LHM slab and the physical process can be described by a simple model.Comment: 4 pages, 2 figure