Closed timelike curves and chronology protection in quantum and classical simulators

In principe, General Relativity seems to allow the existence of closed timelike curves (CTC). However, when quantum effects are considered, it is likely that their existence is prevented by some kind of chronological protection mechanism, as Hawking conjectured. Confirming or refuting the conjecture would require a full quantum theory of gravity. Meanwhile, the use of simulations could shed some light on this issue. We propose simulations of CTCs in a quantum system as well as in a classical one. In the quantum simulation, some restrictions appear that are not present in the classical setup, which could be interpreted as an analogue of a chronology protection mechanism.Comment: 6 pages, 4 figures. v2: published versio

Perspectiva i tasca pedagògiques des d'una mirada cognitiva

La pedagogía teórica se está aproximando a las ciencias cognitivas. Este camino se ha recorrido a partir de sus preocupaciones sistémicocibernéticas y gracias a un progresivo esfuerzo por abrirse a los enfoques, conceptos y problemas de otras disciplinas preocupadas por la cuestión del conocimiento, principalmente a los de la filosofía, la psicología, la tecnología y la neurociencia. Desde una perspectiva cognitiva se aprecia la necesidad de recuperar para la pedagogía el logos de la emoción y de la memoria y de su papel en la comprensión y resolución de escenarios y problemas educativos, así como de superar la artificial contraposición entre ciencia, arte y humanidades. Dotada de esta mirada, la pedagogía teórica aporta un mayor nivel de integración de las disciplinas pedagógicas y una mayor cercanía a los estudios sobre la cognición, la emoción, la memoria y el pensamiento al mismo tiempo que potencia la eficacia de las acciones sobre los procesos educativos. _____________________________________________________________________________________________________________________ La pédagogie théorique se rapproche des sciences cognitives. Elle a parcouru ce chemin pour répondre à ses préoccupations systémicocybernétiques et grâce à un effort progressif pour s’ouvrir aux perspectives, concepts et problèmes d’autres disciplines préoccupées par la question des connaissances, principalement celles de la philosophie, de la psychologie, de la technologie et de la neuroscience. L’article évalue, dans une perspective cognitive, la nécessité de récupérer pour la pédagogie le logos de l’émotion et de la mémoire ainsi que son rôle dans la compréhension et la résolution de scénarios et de problèmes éducatifs; et dépasser l’opposition artificielle entre science, art et humanités. Dotée de ce regard, la pédagogie théorique apporte un niveau supérieur d’intégration des disciplines pédagogiques ainsi qu’une meilleure approche des études sur la cognition, l’émotion, la mémoire et la pensée, en même temps qu’elle renforce l’efficacité des actions sur les processus éducatifs.La pedagogía teórica se está aproximando a las ciencias cognitivas. Este camino se ha recorrido a partir de sus preocupaciones sistémicocibernéticas y gracias a un progresivo esfuerzo por abrirse a los enfoques, conceptos y problemas de otras disciplinas preocupadas por la cuestión del conocimiento, principalmente a los de la filosofía, la psicología, la tecnología y la neurociencia. Desde una perspectiva cognitiva se aprecia la necesidad de recuperar para la pedagogía el logos de la emoción y de la memoria y de su papel en la comprensión y resolución de escenarios y problemas educativos, así como de superar la artificial contraposición entre ciencia, arte y humanidades. Dotada de esta mirada, la pedagogía teórica aporta un mayor nivel de integración de las disciplinas pedagógicas y una mayor cercanía a los estudios sobre la cognición, la emoción, la memoria y el pensamiento al mismo tiempo que potencia la eficacia de las acciones sobre los procesos educativos.Pedagogical theory is approaching the cognitive sciences. This journey takes us from a preoccupation with cybernetic-systems, and thanks to a continuous effort to open itself up in its focus, to concepts and problems of other disciplines preoccupied by the question of knowledge, principally to philosophy, psychology, technology and neuroscience. From the cognitive perspective it appreciates how necessary it is for pedagogy to recover the logos of emotion and memory, and their role in the comprehension and resolution of educational situations and problems, in this way overcoming the false opposition between science, art, and the humanities. From this perspective, pedagogical theory carries a better level of integration of the pedagogical disciplines and a greater pertinence to studies of cognition, emotion, memory and thought, which at the same time encourage efficiency in the initiatives concerning educational processes

La educación multicultural

La educación multicultural.</span

La formación de la competencia cognitiva del profesor

La formación del educador se desarrolla a lo largo de toda su vida profesional. La crisis actual de los sistemas educativos exige formar a los profesores en todas las dimensiones de su personalidad. El enfoque de currículo basado en competencias ofrece oportunidades para el desarrollo de la competencia profesional del educador, y más en concreto de su dimensión cognitiva. La actual situación de definición de nuevas titulaciones de maestros y profesores y el proceso del Espacio Europeo de Educación Superior [EEES] ofrecen oportunidades para elaborar currículos orientados a formar la competencia cognitiva en relación con los alumnos, la organización educativa, la familia y la cultura

Multi-Sensor System For Level Measurements With Optical Fibres

A system for measuring liquid level in multiple tanks using optical fibre technology has been developed. The oil field service industry can benefit from this intrinsically safe technology. Plastic optical fibre (POF) sensor heads are excited by a 650 nm laser. Laser diodes are housed in ST connectors to obtain compact and rough prototypes and these connectors are also used in the fibre pigtails. Optical multiplexing is used to increase the measuring safety area. POF splitters and connectors are used to combine all the receiving sensor head fibres in a single one. Frequency division multiplexing is used to address each sensor head. The global system is controlled through a user friendly software application running in a PC connected to the system via an RS-232 port. A scalable prototype with a range greater than 2 meter, good linearity, better than 1.5% FS (full scale), high accuracy and resolution is developed using a unique lens to collimate and focus the light. Measurements are taken to validate the designs. Up to 8 sensor heads can be connected in the present implementation. But a greater number of sensors can be allocated with minor modifications in the electronics.Universidad Carlos III de MadridPublicad

Emprendimientos Asociativos, Empresas Recuperadas y Economía Social en la Argentina

Hacia fines de siglo XX Argentina atravesaba una crisis social, política y económica de dimensiones inéditas cuyos rasgos más significativos se tradujeron en el aumento de la pobreza y la desigualdad y en una crisis estructural del mercado de trabajo. En este contexto, han surgido numerosas estrategias de recuperación o generación de nuevas fuentes de trabajo, algunas de las cuales se las identifica como parte de un amplio y heterogéneo conjunto de experiencias de economía social. En particular, en este trabajo nos centraremos en el análisis de 611 emprendimientos Asociativos mercantiles y 50 empresas recuperadas de Argentina a fin de caracterizar estas experiencias y mostrar su desempeño en relación a la recuperación y creación de fuentes de trabajo. Para ello nos basaremos en los datos construidos en el estudio “Emprendimientos socioeconómicos asociativos: su vulnerabilidad y sostenibilidad” (ICO-UNGS, 2006).Towards the end of the twentieth century, Argentina faced a social, political and economic crisis of monumental dimensions. This emergency translated into increased poverty and inequality, and a structural crisis in the job market. In this context, a number of strategies arose, aimed at recuperating some of the loss, and generating new possibilities in the job market. Some of these strategies were identified as part of a wide-ranging and heterogeneous series of experiments in social economics. This work will focus on an analysis of 611 associate market initiatives and 50 recuperated companies in Argentina, for the purpose of characterizing these experiences and showing their drive to create and regenerate sources of employment. To achieve this, we will take as our starting point the data collected for the Study "Socio-Economic Associative Initiatives: Vulnerability and Sustainability" (ICO-UNGS, 2006)

Optimizing the spatial spread of a quantum walk.

We devise a protocol to build 1D time-dependent quantum walks in 1D maximizing the spatial spread throughout the procedure. We allow only one of the physical parameters of the coin-tossing operator to vary, i.e. the angle θ, such that for θ = 0 we have the ˆσz, while for θ = π/4 we obtain the Hadamard gate. The optimal θ sequences present non-trivial patterns, with mostly θ ≈ 0 alternated with θ ≈ π/4 values after increasingly long periods. We provide an analysis of the entanglement properties, quasi-energy spectrum and survival probability, providing a full physical picture.peer-reviewed1,34 M

A Rigorous Approach to High-Resolution Entropy-Constrained Vector Quantization

The nonnegativity of relative entropy implies that the differential entropy of a random vector X with probability density function (pdf) f is upper-bounded by -E[log g(X)]for any arbitrary pdf g. Using this inequality with a cleverly chosen g, we derive a lower bound on the asymptotic excess rate of entropy-constrained vector quantization for d-dimensional sources and rth-power distortion, where the asymptotic excess rate is defined as the difference between the smallest output entropy of a vector quantizer satisfying the distortion constraint and the rate-distortion function in the limit as the distortion tends to zero. Specialized to the one-dimensional case, this lower bound coincides with the asymptotic excess rate achieved by a uniform quantizer, thereby recovering the result by Gish and Pierce that uniform quantizers are asymptotically optimal as the allowed distortion tends to zero. Furthermore, in the one-dimensional case, the derivation of the lower bound reveals a necessary condition for a sequence of quantizers to be asymptotically optimal. This condition implies that any sequence of asymptotically optimal almost-regular quantizers must converge to a uniform quantizer as the distortion tends to zero. While the obtained lower bound itself is not novel, to the best of our knowledge, we present the first rigorous derivation that follows the direct approach by Gish and Pierce without resorting to heuristic high-resolution approximations commonly found in the quantization literature. Furthermore, our derivation holds for all d-dimensional sources having finite differential entropy and whose integer part has finite entropy. In contrast to Gish and Pierce, we do not require additional constraints on the continuity or decay of the source pdf.This work has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement number 714161), from the 7th European Union Framework Programme under Grant 333680, from the Ministerio de Economía y Competitividad of Spain under Grants TEC2013-41718-R, RYC-2014-16332, IJCI-2015-27020, TEC2015-69648-REDC, and TEC2016-78434-C3-3-R (AEI/FEDER, EU), and from the Comunidad de Madrid under Grant S2103/ICE-2845. The material in this paper was presented in part at the 2016 IEEE International Symposium on Information Theory, Barcelona, Spain, July 2016