739 research outputs found
Convergent null data expansions at space-like infinity of stationary vacuum solutions
We present a characterization of the asymptotics of all asymptotically flat
stationary vacuum solutions of Einstein's field equations. This
characterization is given in terms of two sequences of symmetric trace free
tensors (we call them the `null data'), which determine a formal expansion of
the solution, and which are in a one to one correspondence to Hansen's
multipoles. We obtain necessary and sufficient growth estimates on the null
data to define an absolutely convergent series in a neighbourhood of spatial
infinity. This provides a complete characterization of all asymptotically flat
stationary vacuum solutions to the field equations.Comment: 71 pages, no figure
Central banking in the iberian peninsula : a comparison.
The paper explores the similiraties and differences between the origin, behavior and evolution of the central banks of Portugal and Spain. Portugal and Spain are two countries that share the same peninsular space in the west corner of Europe. Though different in size and population, the political, social and economic history of both nations offer more similarities than differences. In the financial sphere, he resemblances are remarkable. Both nations exhibit very low levels of financial intermediation, as measured by the ratio between total bank deposits and GDP. Another common feature of both Iberian nations is the dominance exerted by a sole institution. However, we also find some divergences between the financial structures of the two countries that are worth noting. Three differences merit our particular attention in this paper. The first diversity refers to the distinct composition of the quantity of money. The monetary regime is the second difference between the two countries (Portugal joined the gold standard while Spain remained off the gold standard). Finally, the Bank of Portugal and the Bank of Spain exhibit also significant contrasts in their behavior as central banks.Central banks; Monetary policy; Gold standard; Portugal; Spain;
Extremal black hole initial data deformations
We study deformations of axially symmetric initial data for Einstein-Maxwell
equations satisfying the time-rotation (-) symmetry and containing one
asymptotically cylindrical end and one asymptotically flat end. We find that
the - symmetry implies the existence of a family of deformed data
having the same horizon structure. This result allows us to measure how close
solutions to Lichnerowicz equation are when arising from nearby free data.Comment: 21 pages, no figures, final versio
Horizon area--angular momentum inequality for a class of axially symmetric black holes
We prove an inequality between horizon area and angular momentum for a class
of axially symmetric black holes. This class includes initial conditions with
an isometry which leaves fixed a two-surface. These initial conditions have
been extensively used in the numerical evolution of rotating black holes. They
can describe highly distorted black holes, not necessarily near equilibrium. We
also prove the inequality on extreme throat initial data, extending previous
results.Comment: 23 pages, 5 figures. We improved the hypothesis of the main theore
Financial crises and financial reforms in Spain : what have we learned?.
Like the rest of the world, Spain has suffered frequent financial crises and undergone several changes in its regulatory framework. There have been crises that have been followed by reforms of the financial structure, and also troubled financial times with no modification of the regulatory and supervisory regime. In various instances, regulatory changes have predated financial crises, but in others banking crises have occurred without reference to changes in the regulatory regime. Regulation and supervision has been usually absent in the XIXth century, while in the XXth century policy makers have been more active and diligent. Moreover, all major financial crises have been followed by intense financial restructuring, although as elsewhere banking restructuring and interventions not always have been successful (in fact, the cases of failures and mixed results overcome the successful cases). The paper provides a short history of the major financial crises in Spain from 1856 to the present, and also reviews the main financial reforms and the distinctive regulatory regimes that have been in place in this last 150 years time span.Spanish banking; Financial crisis; Financial regulations; Banking reforms;
Minimal data at a given point of space for solutions to certain geometric systems
We consider a geometrical system of equations for a three dimensional
Riemannian manifold. This system of equations has been constructed as to
include several physically interesting systems of equations, such as the
stationary Einstein vacuum field equations or harmonic maps coupled to gravity
in three dimensions. We give a characterization of its solutions in a
neighbourhood of a given point through sequences of symmetric trace free
tensors (referred to as `null data'). We show that the null data determine a
formal expansion of the solution and we obtain necessary and sufficient growth
estimates on the null data for the formal expansion to be absolutely convergent
in a neighbourhood of the given point. This provides a complete
characterization of all the solutions to the given system of equations around
that point.Comment: 26 pages, no figure
Central banking in the iberian peninsula : a comparison
The paper explores the similiraties and differences between the origin, behavior
and evolution of the central banks of Portugal and Spain. Portugal and Spain
are two countries that share the same peninsular space in the west corner of
Europe. Though different in size and population, the political, social and
economic history of both nations offer more similarities than differences. In the
financial sphere, he resemblances are remarkable. Both nations exhibit very
low levels of financial intermediation, as measured by the ratio between total
bank deposits and GDP. Another common feature of both Iberian nations is the
dominance exerted by a sole institution. However, we also find some
divergences between the financial structures of the two countries that are
worth noting. Three differences merit our particular attention in this paper. The
first diversity refers to the distinct composition of the quantity of money. The
monetary regime is the second difference between the two countries (Portugal
joined the gold standard while Spain remained off the gold standard). Finally,
the Bank of Portugal and the Bank of Spain exhibit also significant contrasts in
their behavior as central banks
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