Horizon thermodynamics and spacetime mappings

When black holes are dynamical, event horizons are replaced by apparent and trapping horizons. Conformal and Kerr-Schild transformations are widely used in relation with dynamical black holes and we study the behaviour under such transformations of quantities related to the thermodynamics of these horizons, such as the Misner-Sharp-Hernandez mass (internal energy), the Kodama vector, surface gravity, and temperature. The transformation properties are not those expected on the basis of naive arguments.Comment: 12 page

The Determinants of the Price-Cost Margins of the Manufacturing Firms in Turkey

This study examines the determinants of the price-cost margins in the Turkish manufacturing industry spanning from 1995 to 2003. The literature on this subject points to the importance of market structure, business cycles and input costs. Utilizing panel data econometric techniques on a large number of manufacturing firms by conditioning on their firm size, age, ownership and export orientation, the study finds that there exists a marked difference among the firms’ pricing behaviors according to their market share. Import penetration seems to be ineffective to reduce the price-cost margins of large, high market share and foreign partner firms, while exporting activity was observed to act as a factor to enhance competition. The analysis also suggests that price-cost margins behave pro-cyclically in general and an appreciation of the domestic currency reduces price-cost margins by way of lowering input costs.Price-cost margins, Market Structure, Import Penetration

Are quantization rules for horizon areas universal?

Doubts have been expressed on the universality of holographic/string-inspired quantization rules for the horizon areas of stationary black holes or the products of their radii, already in simple 4-dimensional general relativity. Realistic black holes are not stationary but time-dependent. Using two examples of 4D general-relativistic spacetimes containing dynamical black holes for at least part of the time, it is shown that the quantization rules (even counting virtual horizons) cannot hold, except possibly at isolated instants of time, and do not seem to be universal.Comment: One example and one figure added, two figures improved, bibliography expanded and updated. Matches the version accepted for publication in Phys. Rev.