Extraction of Black Hole Geometry in Exactly Quantized Two Dimensional Dilaton Gravity

Based on our previous work, in which a model of two dimensional dilaton gravity of the type proposed by Callan, Giddings, Harvey and Strominger was rigorously quantized, we explicitly demonstrate how one can extract space-time geometry in exactly solvable theory of quantum gravity. In particular, we have been able to produce a prototypical configuration in which a ( smeared ) matter shock wave generates a black hole without naked sigularity.Comment: LATEX file 10 pages. UT-Komaba 93-13. 1 figure in postscrip

The role of the electromagnetic field in the formation of domains in the process of symmetry breaking phase transitions

In the framework of quantum field theory we discuss the emergence of a phase locking among the electromagnetic modes and the matter components on an extended space-time region. We discuss the formation of extended domains exhibiting in their fundamental states non-vanishing order parameters, whose existence is not included in the Lagrangian. Our discussion is motivated by the interest in the study of the general problem of the stability of mesoscopic and macroscopic complex systems arising from fluctuating quantum components in connection with the problem of defect formation during the process of non-equilibrium symmetry breaking phase transitions characterized by an order parameter.Comment: Physical Review A, in the pres

Quantum Black Hole Evaporation

We investigate a recently proposed model for a full quantum description of two-dimensional black hole evaporation, in which a reflecting boundary condition is imposed in the strong coupling region. It is shown that in this model each initial state is mapped to a well-defined asymptotic out-state, provided one performs a certain projection in the gravitational zero mode sector. We find that for an incoming localized energy pulse, the corresponding out-going state contains approximately thermal radiation, in accordance with semi-classical predictions. In addition, our model allows for certain acausal strong coupling effects near the singularity, that give rise to corrections to the Hawking spectrum and restore the coherence of the out-state. To an asymptotic observer these corrections appear to originate from behind the receding apparent horizon and start to influence the out-going state long before the black hole has emitted most of its mass. Finally, by putting the system in a finite box, we are able to derive some algebraic properties of the scattering matrix and prove that the final state contains all initial information.Comment: 37 pages (figs 2 and 3 included as uuencoded compressed tar file), Latex, needs epsf.tex, PUPT-1395, IASSNS-HEP-93/25 (revised version has minor corrections, one reference added

A Unified Approach to Solvable Models of Dilaton Gravity in Two-Dimensions Based on Symmetry

A large class of solvable models of dilaton gravity in two space-time dimensions, capable of describing black hole geometry, are analyzed in a unified way as non-linear sigma models possessing a special symmetry. This symmetry, which can be neatly formulated in the target-space-covariant manner, allows one to decompose the non-linearly interacting dilaton-gravity system into a free field and a field satisfying the Liouville equation with in general non-vanishing cosmological term. In this formulation, all the existent models are shown to fall into the category with vanishing cosmological constant. General analysis of the space-time structureinduced by a matter shock wave is performed and new models, with and without the cosmological term, are discussed.Comment: 29 pages, LaTe

Detection of Extensive Cross-Neutralization between Pandemic and Seasonal A/H1N1 Influenza Viruses Using a Pseudotype Neutralization Assay

BACKGROUND: Cross-immunity between seasonal and pandemic A/H1N1 influenza viruses remains uncertain. In particular, the extent that previous infection or vaccination by seasonal A/H1N1 viruses can elicit protective immunity against pandemic A/H1N1 is unclear. METHODOLOGY/PRINCIPAL FINDINGS: Neutralizing titers against seasonal A/H1N1 (A/Brisbane/59/2007) and against pandemic A/H1N1 (A/California/04/2009) were measured using an HIV-1-based pseudovirus neutralization assay. Using this highly sensitive assay, we found that a large fraction of subjects who had never been exposed to pandemic A/H1N1 express high levels of pandemic A/H1N1 neutralizing titers. A significant correlation was seen between neutralization of pandemic A/H1N1 and neutralization of a standard seasonal A/H1N1 strain. Significantly higher pandemic A/H1N1 neutralizing titers were measured in subjects who had received vaccination against seasonal influenza in 2008-2009. Higher pandemic neutralizing titers were also measured in subjects over 60 years of age. CONCLUSIONS/SIGNIFICANCE: Our findings reveal that the extent of protective cross-immunity between seasonal and pandemic A/H1N1 influenza viruses may be more important than previously estimated. This cross-immunity could provide a possible explanation of the relatively mild profile of the recent influenza pandemic

Water: a medium where dissipative structures are produced by a coherent dynamics.

The Belousov-Zhabotinsky phenomenon is analyzed in a framework where the dynamics of dissipative structures outlined by Prigogine is implemented through the collective dynamics produced in liquid water by Quantum Electrodynamics, which has received recently some experimental support. A mechanism allowing the appearance of self-produced oscillations is suggested

Influence of wall thickness on microstructure and mechanical properties of thin-walled 316L stainless steel produced by laser powder bed fusion

Laser powder bed fusion (L-PBF) allows for the fabrication of samples with complex geometries based on thin struts or walls. However, only few studies have focused on the effect of these geometries on the properties of the material fabricated using this technology. In this work, we studied the impact of wall thicknesses below 1 mm on microstructure formation and mechanical properties in 316L parts fabricated by L-PBF. The size and geometry of melt pools varied significantly between different wall thicknesses due to powder denudation and local preheating, resulting in non-symmetrical melt pools for thicker samples. Furthermore, in the sub-grain microstructure, the thinnest samples consisted of solidification cells oriented almost parallel to the building direction. In the thicker walls, side branching and slender columnar grains were observed in the center lines of the melt pools. On the grain size scale, the thinnest samples consisted of finer grains with a more pronounced texture 〈100〉, while large grains growing parallel to the build direction and texture 〈101〉 were found for the thicker samples. Mechanical tests showed that the strength and ductility were higher in thicker samples, which was attributed to finer solidification cells