In the first author's thesis [10], a sequential language, LRT, for real number computation is investigated. That thesis includes a proof that all polynomials are programmable, but that work comes short of giving a complete characterization of the expressive power of the language even for first-order functions. The technical problem is that LRT is non-deterministic. So a natural characterization of its expressive power should be in terms of relations rather than in terms of functions. In [2], Brattka examines a formalization (...) of recursive relations in the style of Kleene's recursive functions on the natural numbers. This paper is an expanded version of [13] which establishes the expressive power of LRTp, a variant of LRT, in terms of Brattka's recursive relations. Because Brattka already did the work of establishing the precise connection between his recursive relations and Type 2 Theory of Effectivity, we thus obtain a complete characterization of first-order definability in LRTp. (shrink)

We discuss the concepts of Weyl and Riemann frames in the context of metric theories of gravity and state the fact that they are completely equivalent as far as geodesic motion is concerned. We apply this result to conformally flat spacetimes and show that a new picture arises when a Riemannian spacetime is taken by means of geometrical gauge transformations into a Minkowskian flat spacetime. We find out that in the Weyl frame gravity is described by a scalar field. We (...) give some examples of how conformally flat spacetime configurations look when viewed from the standpoint of a Weyl frame. We show that in the non-relativistic and weak field regime the Weyl scalar field may be identified with the Newtonian gravitational potential. We suggest an equation for the scalar field by varying the Einstein-Hilbert action restricted to the class of conformally-flat spacetimes. We revisit Einstein and Fokker’s interpretation of Nordström scalar gravity theory and draw an analogy between this approach and the Weyl gauge formalism. We briefly take a look at two-dimensional gravity as viewed in the Weyl frame and address the question of quantizing a conformally flat spacetime by going to the Weyl frame. (shrink)

The importance of non-codifying DNA polymorphism for the administration of justice is now well known. In Spain, however, this type of test has given rise to questions in recent years: Should consent be obtained before biological samples are taken from an individual for DNA analysis? Does society perceive these techniques and methods of analysis as being reliable? There appears to be lack of knowledge concerning the basic norms that regulate databases containing private or personal information and the protection that information (...) of this type must be given. This opinion survey and the subsequent analysis of the results in ethical terms may serve to reveal the criteria and the degree of information that society has with regard to DNA databases. In the study, 73.20% of the population surveyed was in favour of specific legislation for computer files in which DNA analysis results for forensic purposes are stored. (shrink)

We present an experimental test of the validity of the Pauli Exclusion Principle for electrons based on the concept put forward a few years ago by Ramberg and Snow. In this experiment we perform a very accurate search of X-rays from the Pauli-forbidden atomic transitions of electrons in the already filled 1S shells of copper atoms. Although the experiment has a simple structure, it poses deep conceptual and interpretational problems. Here we describe the experimental method and recent experimental results, which (...) we interpret as an upper limit for the probability to violate the Pauli Exclusion Principle. We present also future plans to upgrade the experimental apparatus using Silicon Drift Detectors. (shrink)

In this paper we describe an experimental test of the validity of the Pauli Exclusion Principle (for electrons) which is based on a straightforward idea put forward a few years ago by Ramberg and Snow (Phys. Lett. B 238:438, 1990). We perform a very accurate search of X-rays from the Pauli-forbidden atomic transitions of electrons in the already filled 1S shells of copper atoms. Although the experiment has a very simple structure, it poses deep conceptual and interpretational problems. Here we (...) describe the experimental method and recent experimental results, which we interpret in the framework of quon theory. We also present future plans to upgrade the experimental apparatus using Silicon Drift Detectors. (shrink)

El libro de Herbert Marcuse Entre fenomenología y marxismo. Escritos filosóficos 1928-1933 viene a satisfacer la demanda de los lectores del autor de América latina, y de habla hispana en general, de tener una edición definitiva de sus trabajos de juventud. Marcuse nos había llegado como uno de los principales representantes del llamado marxismo heterodoxo del siglo XX. A su nombre habíamos asociado principalmente el proyecto de la Escuela de Frankfurt y la constitución de una teoría crítica de la sociedad; (...) el auge de los movimientos sociales de protesta de la generación del 68, la fundación de una nueva izquierda internacional, así como el análisis teórico sobre la dominación de las necesidades y deseos en las sociedades industriales avanzadas; los intentos por pensar la clase revolucionaria más allá del proletariado industrial y una original propuesta de lectura de la estructura históricosocial desarrollada por Marx en conjunto con la histórico-subjetiva desarrollada por Freud. Obras como Razón y revolución y El marxismo soviético, sentaron las bases para una nueva interpretación de la dialéctica de Hegel y de Marx y la denuncia de las formas esclerotizadas del marxismo en las directrices ideológicas de la Unión Soviética. (shrink)