We investigate the possibility that gamma-ray bursts are powered by a central engine consisting of a black hole with an external magnetic field anchored in a surrounding disk or torus. The energy source is then the rotation of the black hole, and it is extracted electromagnetically via a Poynting flux, a mechanism first proposed by Blandford and Znajek (1997) for AGN. Our reanalysis of the stre...

We investigate the possibility that gamma-ray bursts are powered by a central engine consisting of a black hole with an external magnetic field anchored in a surrounding disk or torus. The energy source is then the rotation of the black hole, and it is extracted electromagnetically via a Poynting flux, a mechanism first proposed by Blandford and Znajek (1997) for AGN. Our reanalysis of the stre...

We present the gravitational action and Hamiltonian for a spatially bounded region of an eternal black hole. The Hamiltonian is of the general form H = H+ − H−, where H+ and H− are respectively the Hamiltonian for the regions M+ and M− located in the left and right wedges of the spacetime. We construct explicitly the quasilocal energy for the system and discuss its dependence on the time direct...

A concise survey of the black hole information paradox and its current status is given. A summary is also given of recent arguments against remnants. The assumptions underlying remnants, namely unitarity and causality, would imply that Reissner Nordstrom black holes have infinite internal states. These can be argued to lead to an unacceptable infinite production rate of such black holes in back...

As a nontraditional processing technology, electrochemical discharge machining (ECDM) can process glass and engineering ceramics precisely. This technology has proven to be potential for 3D microstructure. However, the key expanding application of ECDM is how improve accuracy. research conducted micro-hole microgroove machining. Power voltage frequency influence on hole efficiency, entrance dia...

After a short discussion of all conventional core level spectroscopies within the single particle model, the effects of the coupling of the core and valence wave function on the x-ray emission spectral shapes is discussed. It will be shown that these so-called multiplet effects strongly affect all x-ray emission spectra taken around the metal 2p resonances. In case of 1s resonances, valence ban...

When these diodes are exposed to photons of energy greater than 1.12 eV (wavelength less than 1100 nm) electron-hole pairs (carriers) are created. These photogenerated carriers are separated by the p-n junction electric field and a current proportional to the number of electron-hole pairs created flows through an external circuit. For the majority of XUV photons, about 3.7 eV energy is required...

Optogalvanic effects are changes in the electrical properties of a gas discharge caused by illumination with radiation at a wavelength corresponding to an atomic or molecular transition. The resurgence of interest in optogalvanic effects stems in a large measure from the unique properties of lasers such as: the high powers, the tunability, the narrow bandwidths, and the controllability of pulse...