Bose-Einstein condensation in quasi-2D systems: applications to high Tc superconductivity

We describe high-Tc superconductivity in layered materials within a BCS theory as a BEC of massless-like Cooper pairons satisfying a linear dispersion relation, and propagating within quasi-2D layers of finite width defined by the charge distribution about the CuO_2 planes. We obtain a closed formula for the critical temperature, Tc, that depends on the layer width, the binding energy of Cooper's pairs, and the average in-plane penetration depth. This formula reasonably reproduces empirical values of superconducting transition temperatures for several different cuprate materials near the optimal doping regime, as well as for YBCO films with different doping degrees.Comment: 5 pages, 1 figur

Los nuevos leviatanes. Teoria de los sujetos colectivos. [Reseña]

Reseña de: Nicolás LÓPEZ CALERA, Los nuevos leviatanes. Teoria de los sujetos colectivos, Marcial Pons, Madrid, 2007, 150 pp

Kant y la guerra. Una revisión de la Paz Perpetua desde las preguntas actuales. [Reseña]

Reseña de: Francisco José CONTRERAS PELÁEZ, Kant y la guerra. Una revisión de la Paz Perpetua desde las preguntas actuales. Tirant lo blanch. Valencia, 2007, 310 pp

Arthur Kaufmann: En la encrucijada de la filosofía jurídica alemana de la posguerra. [Reseña]

Reseña de: José Antonio SANTOS, Arthur Kaufmann: En la encrucijada de la filosofía jurídica alemana de la posguerra, Comares, Granada, 2008, 326 pp

Una salida a los conflictos entre el Tribunal de Estrasburgo y el Tribunal de Luxemburgo

La perspectiva de integración de los diferentes ordenamientos jurídicos en la protección de los derechos fundamentales en Europa exige que la Unión Europea se adhiera el CEDH con el fin de paliar las divergencias y tensiones entre tribunales europeos, así como de éstos con los nacionales. Asimismo quedará con ello definido el estándar mínimo de protección de los derechos fundamentales en el ámbito europeo, al que deberán someterse, de forma necesaria, no solamente los ordenamientos constitucionales sino, igualmente, el ordenamiento de la Unión Europea

Frequency UWB Channel

Ultra wideband (UWB) transmission systems are characterized with either a fractional bandwidth of more that 20%, or a large absolute bandwidth (>500 MHz) in the 3.1 GHz to 10.6 GHz band, and for a very low power spectral density (-41.25 dBm/MHz, equivalent to 75nW/MHz), which allows to share the spectrum with other narrowband and wideband systems without causing interference (FCC, 2002), this spectral allocation has initiated an extremely productive activity for industry and academia. Wireless communications experts now consider UWB as available spectrum to be utilized with a variety of techniques and not specifically related to the generation and detection of short RF pulses as in the past (Batra, 2004). For this reason, UWB systems are emerging as the best solution for high speed short range indoor wireless communication and sensor networks, with applications in home networking, high-quality multimedia content delivery, radars systems of high accuracy, etc. UWB has many attractive properties, including low interference to and from other wireless systems, easier wall and floor penetration, and inherent security due to its Low Probability Interception/Detection (LPI/D). Two of the most promising applications of UWB are High Data Rate Wireless Personal Area Network (HDR-WPAN), and Sensor Networks, where the good ranging and geo-location capabilities of UWB are particularly useful and of interest for military applications (Molisch, 2005)