Local Realistic Theory for PDC Experiments Based on the Wigner Formalism

In this article we present a local hidden variables model for all experiments involving photon pairs produced in parametric down conversion, based on the Wigner representation of the radiation field. A modification of the standard quantum theory of detection is made in order to give a local realist explanation of the counting rates in photodetectors. This model involves the existence of a real zeropoint field, such that the vacumm level of radiation lies below the threshold of the detectors.Comment: 7 pages, no figure

Ley de calidad de la educación y LOGSE: una polémica ficticia y un paso más sobre una misma base ideológica

Este trabajo se propone poner de relieve la existencia de una unidad fundamental, en los objetivos, la ideología y el diseño práctico, entre el sistema educativo de la LOCE y el de la LOGSE, a pesar de algunas apariencias. Esta identidad básica entre ambos sistemas motiva que gran parte de la oposición a la LOCE haya sido superficial y ficticia, a base de la repetición de eslóganes publicitarios, como el de la discriminación social, aplicables igualmente al discurso profundo y oculto de la LOGSE -aunque menos a su discurso manifiesto. Nuestro planteamiento, choca con las declaraciones de los partidarios de cada una de las normativas sobre educación (LOCE y LOGSE), que las presentan como contrapuestas, utilizando para ello más la espectacularidad y resonancias de las consignas que la profundidad de la argumentación. También discrepa del sector del profesorado que ha sido víctima del espejismo producido por la eliminación de algunos desmanes de la LOGSE, cuya necesidad de modificación era un clamor plenamente justificado, y ha abrazado acríticamente como salvadora la LOCE.This paper argues that, although some appareances of discrepancy, the goals, ideology and practical design are essentially identical for both the LOCE and LOGSE educational systems. This basic identity entails a superficial and fictitious criticism to the LOCE, founded on the repetition of slogans -as social discrimination- which could be also adressed to the deep and hidden discourse of the LOGSE itself. Our point of view collides with the public declarations of both educational laws defenders, engaged in a dispute in which propaganda prevails over reasoning depth. It also desagrees with the illusive hopes of many teachers whose reasonable opposition to the LOGSE brought them to greet the LOCE as a solution to the deplorable state of current education

Constructivismo radical, marco teórico de investigación y enseñanza de las ciencias

The article on radical constructivism criticizes its claim of being an original paradigm as well as criticizing some contradictions and scarcely justified theoretical leaps, and some specific problems over previous ideas in teaching and theoretical frames in scientific research. The critique underlines the controversial subject of empirical and experimental methods in learning and research and proposes a comparison between empiricism and radical constructivism axioms (with a suggested isomorphism between supposed opposing theories) as well as a tendency for both paradigms to slip towards epistemological realism. Also discussed are some aspects regarding research management and education (LOGSE)

Integration of aerial and terrestrial locomotion modes in a bioinspired robotic system

In robotics, locomotion is a fundamental task for the development of high-level activities such as navigation. For a robotic system, the challenge of evading environmental obstacles depends both on its physical capabilities and on the strategies followed to achieve it. Thus, a robot with the ability to develop several modes of locomotion (walking, flying or swimming) has a greater probability of success in achieving its goal than a robot that develops only one. In nature, Hymenoptera insects use terrestrial and aerial modes of locomotion to carry out their activities. Mimicry the physical capabilities of these insects opens the possibility of improvements in the area of robotic locomotion. Therefore, this work seeks to generate a bio-inspired robotic system that integrates the terrestrial and aerial modes of locomotion. The methodology used in this research project has considered the anatomical study and characterization of Hymenoptera insects locomotion, the proposal of conceptual models that integrate terrestrial and aerial modes locomotion, the construction of a physical platform and experimental testing of the system. In addition, a gait generation approach based on an artificial nervous system of coupled nonlinear oscillators has been proposed. This approach has resulted in the generation of a coherent and functional gait pattern that, in combination with the flight capabilities of the system, has constituted an aero-terrestrial robot. The results obtained in this work include the construction of a bioinspired physical platform, the generation of the gait process using an artificial nervous system and the experimental tests on the integration of aero-terrestrial locomotion.Conacyt - Becario Naciona

Enabling Practical IPsec authentication for the Internet

On the Move to Meaningful Internet Systems 2006: OTM 2006 Workshops (First International Workshop on Information Security (IS'06), OTM Federated Conferences and workshops). Montpellier, Oct,/Nov. 2006There is a strong consensus about the need for IPsec, although its use is not widespread for end-to-end communications. One of the main reasons for this is the difficulty for authenticating two end-hosts that do not share a secret or do not rely on a common Certification Authority. In this paper we propose a modification to IKE to use reverse DNS and DNSSEC (named DNSSEC-to-IKE) to provide end-to-end authentication to Internet hosts that do not share any secret, without requiring the deployment of a new infrastructure. We perform a comparative analysis in terms of requirements, provided security and performance with state-of-the-art IKE authentication methods and with a recent proposal for IPv6 based on CGA. We conclude that DNSSEC-to-IKE enables the use of IPsec in a broad range of scenarios in which it was not applicable, at the price of offering slightly less security and incurring in higher performance costs.Universidad de Montpellier IIPublicad

A low-power reconfigurable ADC for biomedical sensor interfaces

This paper presents a 12-bit low-voltage low-power reconfigurable Analog-to-Digital Converter (ADC). The design employs Switched Capacitor (SC) techniques and implements a Successive Approximation (SA) algorithm. The ADC can be tuned to handle a large variety of biopotential signals, with digitally selectable resolution and input signal amplitude. It achieves 10.4-bit of effective resolution sampling at 56kS/s, with a power consumption below 3μW from a 1V voltage supply.Ministerio de Educación y Ciencia TEC2006-03022Junta de Andalucía TIC-0281