Gowdy T3T^3 Cosmological Models in N=1 Supergravity

We investigate the canonical quantization of supergravity N=1 in the case of a midisuperspace described by Gowdy $T^3$ cosmological models. The quantum constraints are analyzed and the wave function of the universe is derived explicitly. Unlike the minisuperspace case, we show the existence of physical states in midisuperspace models. The analysis of the wave function of the universe leads to the conclusion that the classical curvature singularity present in the evolution of Gowdy models is removed at the quantum level due to the presence of the Rarita-Schwinger field.Comment: 25 pages and 2 figure

Thermodynamics of firms' growth

The distribution of firms' growth and firms' sizes is a topic under intense scrutiny. In this paper we show that a thermodynamic model based on the Maximum Entropy Principle, with dynamical prior information, can be constructed that adequately describes the dynamics and distribution of firms' growth. Our theoretical framework is tested against a comprehensive data-base of Spanish firms, which covers to a very large extent Spain's economic activity with a total of 1,155,142 firms evolving along a full decade. We show that the empirical exponent of Pareto's law, a rule often observed in the rank distribution of large-size firms, is explained by the capacity of the economic system for creating/destroying firms, and can be used to measure the health of a capitalist-based economy. Indeed, our model predicts that when the exponent is larger that 1, creation of firms is favored; when it is smaller that 1, destruction of firms is favored instead; and when it equals 1 (matching Zipf's law), the system is in a full macroeconomic equilibrium, entailing "free" creation and/or destruction of firms. For medium and smaller firm-sizes, the dynamical regime changes; the whole distribution can no longer be fitted to a single simple analytic form and numerical prediction is required. Our model constitutes the basis of a full predictive framework for the economic evolution of an ensemble of firms that can be potentially used to develop simulations and test hypothetical scenarios, as economic crisis or the response to specific policy measures

Quasi-homogeneous black hole thermodynamics

Although the fundamental equations of ordinary thermodynamic systems are known to correspond to first-degree homogeneous functions, in the case of non-ordinary systems like black holes the corresponding fundamental equations are not homogeneous. We present several arguments, indicating that black holes should be described by means of quasi-homogeneous functions of degree different from one. In particular, we show that imposing the first-degree condition leads to contradictory results in thermodynamics and geometrothermodynamics of black holes. As a consequence, we show that in generalized gravity theories the coupling constants like the cosmological constant, the Born-Infeld parameter or the Gauss-Bonnet constant must be considered as thermodynamic variables

Curvature as a Measure of the Thermodynamic Interaction

We present a systematic and consistent construction of geometrothermodynamics by using Riemannian contact geometry for the phase manifold and harmonic maps for the equilibrium manifold. We present several metrics for the phase manifold that are invariant with respect to Legendre transformations and induce thermodynamic metrics on the equilibrium manifold. We review all the known examples in which the curvature of the thermodynamic metrics can be used as a measure of the thermodynamic interaction

El jardín español: una mirada nueva al paisaje

Cuando Leandro Silva llegó a España en el año 1969 para quedarse defi nitivamente, la situación de la disciplina de la Arquitectura del Paisaje era claramente insufi ciente para un país de una larga y fecunda tradición jardinera y que se situaba ya dentro del ámbito europeo de los países desarrollados. No sólo la inexistencia de una enseñanza reglada ni el desconocimiento de la profesión, propios de regiones más atrasadas, sorprendieron al paisajista uruguayo, sino, además, la pérdida de las referencias hispanomusulmanas en la jardinería española del momento. Fuertemente infl uido por un modelo inglés pintoresco, el jardín contemporáneo español no había sido capaz de asumir los condicionantes de un medio físico –el de la mayor parte de la Penínsulaque no permitía la implantación y conservación de este tipo de jardines: organizados mediante grandes praderas, frondosas y un cierto aire salvaje – el wild garden robinsoniano- y ajenos a nuestra tradición y climatología, fue imposible mantener estos jardines sin un insostenible gasto hídrico. Leandro Silva ya conocía los principales ejemplos de la jardinería hispana, pues había visitado nuestro país en varias ocasiones, y el interés por las grandes realizaciones españolas era una de las muchas razones para asentarse en nuestro país y, especialmente, en Madrid, como él mismo contaba, dada su proximidad de Aranjuez, El Escorial y La Granja. Asimismo, la experiencia que tenía de la arquitectura europea de jardines era muy amplia: su interés por las villas italianas renacentistas, la jardinería clásica francesa -en cotidiano contacto en Versalles- o el paisajismo inglés provenía de sus años de formación tanto en su país natal como en Francia, así como sus múltiples viajes. Por ello, la profunda adaptación de cada jardín a su momento histórico y al medio físico que lo sustenta había penetrado intensamente en el concepto integral que Leandro Silva tenía de la arquitectura del paisaje

El jardín histórico: memoria esencial del paisaje cultural

The permanence of the characteristics of the historic garden and its environment and the evolution of relationships between nature and human are some of the factors of cultural landscape. Historic Garden is included in its environment and depends on it, but its disposition generally extends throughout its surroundings to structure it. Spanish Garden is one of the most dependants on its environment, which is not propitious to gardening; so, it is nec¬essary to modificate this deficient conditions to implant gardens; this modification is organized by the mere garden composition, that is projected beyond the original limits to extend its geometri¬cal pattern to the external territory. Aranjuez is the best example of this fact. A huge territory modified by Phillip the Second that integrate a palace and surrounding buildings, formal gardens, parks, innovate orchards and woods, vertebrated by water –river Tagus and a web of channels