Conductances in normal and normal-superconductor structures

We study theoretically electronic transport through a normal metal-- superconductor (NS) interface and show that more than one conductance may be defined, depending on the pair of chemical potentials whose difference one chooses to relate linearly to the current. We argue that the situation is analogous to that found for purely normal transport, where different conductance formulae can be invoked. We revisit the problem of the "right" conductance formula in a simple language, and analyze its extension to the case of mesoscopic superconductivity. The well-known result that the standard conductance of a NS interface becomes 2 (in units of $2e^2/h$) in the transmissive limit, is viewed here in a different light. We show that it is not directly related to the presence of Andreev reflection, but rather to a particular choice of chemical potentials. This value of 2 is measurable because only one single-contact resistance is involved in a typical experimental setup, in contrast with the purely normal case, where two of them intervene. We introduce an alternative NS conductance that diverges in the transmissive limit due to the inability of Andreev reflection to generate a voltage drop. We illustrate numerically how different choices of chemical potential can yield widely differing I--V curves for a given NS interface.Comment: Minor changes have been introduced and several references have been added, 12 pages, submitted to special issue of ``Superlattices and Microstructures

Simulations of Extreme-Mass-Ratio Inspirals Using Pseudospectral Methods

Extreme-mass-ratio inspirals (EMRIs), stellar-mass compact objects (SCOs) inspiralling into a massive black hole, are one of the main sources of gravitational waves expected for the Laser Interferometer Space Antenna (LISA). To extract the EMRI signals from the expected LISA data stream, which will also contain the instrumental noise as well as other signals, we need very accurate theoretical templates of the gravitational waves that they produce. In order to construct those templates we need to account for the gravitational backreaction, that is, how the gravitational field of the SCO affects its own trajectory. In general relativity, the backreaction can be described in terms of a local self-force, and the foundations to compute it have been laid recently. Due to its complexity, some parts of the calculation of the self-force have to be performed numerically. Here, we report on an ongoing effort towards the computation of the self-force based on time-domain multi-grid pseudospectral methods.Comment: 6 pages, 4 figures, JPCS latex style. Submitted to JPCS (special issue for the proceedings of the 7th International LISA Symposium

La Teología Moral Fundamental italiana después de Veritatis splendor: Propuestas particulares

Este estudio aborda algunas propuestas particulares de la teología italiana para la construcción de la moral fundamental después de la publicación de Veritatis splendor. Se considera la contribución de los autores que, sin ofrecer un proyecto global, han dedicado obras específicas a esta disciplina. La característica más destacada es la centralidad de la conciencia como mediadora entre una fundación cristológica de la moral y la antropología subsiguiente. Se sugiere como una posible línea de investigación para el diálogo con los proyectos globales de Teología Moral fundamental el estudio de la conciencia moral de Jesucristo en su Misterio Pascual

La civiltà dell’amore e il senso della storia. Liberazione cristiana – fraternità – utopia. [Recensión]

Recensión de Carlo Lorenzo ROSSETTI, La civiltà dell'amore e il senso della storia. Liberazione cristiana -fraternità - utopia, Soveria Mannelli: Rubbetino Università, 2009,137 pp., 14 x 21, ISBN 9788849824681

The Role of Consciousness in Triggering Intellectual Habits

When must a specific cognitive habit be called upon to solve a problem? In the subject’s learning process, ‘knowing-to’ is connected with a conscious particular judgment of truth or ‘aha’ moment enacting a new behavioral schema. This paper comments on recent experiments supporting the view that a shift from automatic to controlled forms of inhibition, involving conscious attention, is crucial for detecting errors and activating a new strategy in complex cognitive situations. The part that consciousness plays in this process agrees with its philosophical description as ‘judge of truth’, and can thus be regarded as an essential precursor to the development of higher cognitive habit

Filosofía griega y revelación cristiana. La recepción patrística del Discurso del Areópago.

Durante el siglo XX, la revelación de Dios en la creación como tema teológico ha pasado por diversos enfoques. No obstante, el magisterio de Juan Pablo II ha querido relanzar dicha cuestión atendiendo al contexto de la evangelización contemporánea, para la que el discurso de san Pablo en Atenas ofrece un valor paradigmático. En nuestro estudio, a partir de las referencias patrísticas a este pasaje de mayor interés teológico-fundamental, sugerimos una lectura de la revelación en la creación que supere tanto su mera consideración filosófica como su reducción a una etapa inicial de la revelación histórica

De la experiencia de la amistad al misterio de la caridad. Estudio sobre la evolución histórica de la amistad como analogía teológica desde Elredo de Rieval hasta Santo Tomás de Aquino. [Reseña]

Reseña de Antonio PRIETO LuCENA, De la experiencia de la amistad al misterio de la caridad. Estudio sobre la evolución histórica de la amistad como analogía teológica desde Elredo de Rieval hasta Santo Tomás de Aquino, Publicaciones de la Facultad de Teología San Dámaso («Dissertationes Theologicae», 1), Madrid 2007, 772 pp., 16,5 X 23, ISBN 978-84- 96318-38-0