3,392 research outputs found
Thermodynamic scheme of inhomogeneous perfect fluid mixtures
We analyze the compatibility between the geometrodynamics and thermodynamics
of a binary mixture of perfect fluids which describe inhomogeneous cosmological
models. We generalize the thermodynamic scheme of general relativity to include
the chemical potential of the fluid mixture with non-vanishing entropy
production. This formalism is then applied to the case of Szekeres and Stephani
families of cosmological models. The compatibility conditions turn out to
impose symmetry conditions on the cosmological models in such a way that only
the limiting case of the Friedmann-Robertson-Walker model remains compatible.
This result is an additional indication of the incompatibility between
thermodynamics and relativity
Killing horizons confinement, light-surfaces and horizons replicas
AbstractWe provide a complete characterization of the metric Killing bundles (or metric bundles) of the Kerr geometry. Metric bundles can be generally defined for axially symmetric spacetimes with Killing horizons and, for the case of Kerr geometries, are sets of black holes (BHs) or black holes and naked singularities (NSs) geometries. Each metric of a bundle has an equal limiting photon (orbital) frequency, which defines the bundle and coincides with the frequency of a Killing horizon in the extended plane. In this plane each bundle is represented as a curve tangent to the curve that represents the horizons, which thus emerge as the envelope surfaces of the metric bundles. We show that the horizons frequency can be used to establish a connection between BHs and NSs, providing an alternative representation of such spacetimes in the extended plane and an alternative definition of the BH horizons. We introduce the concept of inner horizon confinement and horizons replicas and study the possibility of detecting their frequencies. We study the bundle characteristic frequencies constraining the inner horizon confinement in the outer region of the plane i.e. the possibility of detect frequency related to the inner horizon, and the horizons replicas, structures which may be detectable for example from the emission spectra of BHs spacetimes. With the replicas we prove the existence of photon orbits with equal orbital frequency of the horizons. It is shown that such observations can be performed close to the rotation axis of the Kerr geometry, depending on the BH spin. We argue that these results could be used to further investigate black holes and their thermodynamic properties
Determinants of domestic and cross-border bank acquisitions in the European Union
This paper analyzes the determinants of bank acquisitions both within and across 25 members of the European Union (EU-25) during the period 1997–2004. Our results suggest that poorly managed banks (those with a high cost-to-income ratio) and larger banks are more likely to be acquired by other banks in the same country. The probability of being a target in a cross-border deal is larger for banks that are quoted in the stock market. Finally, banks operating in more concentrated markets are less likely to be acquired by other banks in the same country but are more likely to be acquired by banks in other EU-25 countries.Banks and banking - Europe
What do premiums paid for bank M&As reflect? the case of the European Union
We analyze the takeover premiums paid for a sample of European bank mergers between 1997 and 2007. We find that acquiring banks value profitable, high-growth, and low-risk targets. We also find that the strength of bank regulation and supervision and of deposit insurance regimes in Europe has measurable effects on takeover pricing. Stricter bank regulatory regimes and stronger deposit insurance schemes lower the takeover premiums paid by acquiring banks. This result, presumably in anticipation of higher compliance costs, is mainly driven by domestic deals. Also, we find no conclusive evidence that bidders seek to extract benefits from regulators either by paying a premium for deals in less regulated regimes or becoming too big to fail.
Self-referenced characterization of space-time couplings in near single-cycle laser pulses
We report on the characterization of space-time couplings in high energy
sub-2-cycle 770nm laser pulses using a self-referencing single-shot method.
Using spatially-encoded arrangement filter-based spectral phase interferometry
for direct electric field reconstruction (SEA-F-SPIDER) we characterize
few-cycle pulses with a wave-front rotation of 2.8x?10^11 rev/sec (1.38 mrad
per half-cycle) and pulses with pulse front tilts ranging from to -0.33 fs/um
to -3.03 fs/um.Comment: 6 pages, 6 figure
Status report of the baseline collimation system of CLIC. Part II
Important efforts have recently been dedicated to the characterisation and
improvement of the design of the post-linac collimation system of the Compact
Linear Collider (CLIC). This system consists of two sections: one dedicated to
the collimation of off-energy particles and another one for betatron
collimation. The energy collimation system is further conceived as protection
system against damage by errant beams. In this respect, special attention is
paid to the optimisation of the energy collimator design. The material and the
physical parameters of the energy collimators are selected to withstand the
impact of an entire bunch train. Concerning the betatron collimation section,
different aspects of the design have been optimised: the transverse collimation
depths have been recalculated in order to reduce the collimator wakefield
effects while maintaining a good efficiency in cleaning the undesired beam
halo; the geometric design of the spoilers has been reviewed to minimise
wakefields; in addition, the optics design has been optimised to improve the
collimation efficiency. This report presents the current status of the the
post-linac collimation system of CLIC. Part II is mainly dedicated to the study
of the betatron collimation system and collimator wakefield effects.Comment: 25 pages, 13 figure
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