Materias primas de la Luna para emprender la colonización espacial

1 página.-- Reportaje.Peer reviewe

Progressive encoding with non-linear source codes for compression of low-entropy sources

We propose a novel scheme for source coding of non-uniform memoryless binary sources based on progressively encoding the input sequence with non-linear encoders. At each stage, a number of source bits is perfectly recovered, and these bits are thus not encoded in the next stage. The last stage consists of an LDPC code acting as a source encoder over the bits that have not been recovered in the previous stages.Peer ReviewedPostprint (published version

Non-linear graph-based codes for joint source-channel coding

We study the behavior of a new family of nonlinear graph-based codes, previously introduced for compression of asymmetric binary memoryless sources, for the joint source-channel coding scenario in which the codewords are transmitted through an additive white Gaussian noise channel. We focus on low entropy sources (with high redundancy) and compression rates. Monte Carlo simulation and density evolution results show that the proposed family, with a regular and simple parametrization of the degree profiles, outperforms linear codes.Peer ReviewedPostprint (published version

Combining the Burrows-Wheeler Transform and RCM-LDGM Codes for the Transmission of Sources with Memory at High Spectral Efficiencies

In this paper, we look at the problem of implementing high-throughput Joint SourceChannel (JSC) coding schemes for the transmission of binary sources with memory over AWGN channels. The sources are modeled either by a Markov chain (MC) or a hidden Markov model (HMM). We propose a coding scheme based on the Burrows-Wheeler Transform (BWT) and the parallel concatenation of Rate-Compatible Modulation and Low-Density Generator Matrix (RCM-LDGM) codes. The proposed scheme uses the BWT to convert the original source with memory into a set of independent non-uniform Discrete Memoryless (DMS) binary sources, which are then separately encoded, with optimal rates, using RCM-LDGM codes

On the Performance of Interleavers for Quantum Turbo Codes

Quantum turbo codes (QTC) have shown excellent error correction capabilities in the setting of quantum communication, achieving a performance less than 1 dB away from their corresponding hashing bounds. Existing QTCs have been constructed using uniform random interleavers. However, interleaver design plays an important role in the optimization of classical turbo codes. Consequently, inspired by the widely used classical-to-quantum isomorphism, this paper studies the integration of classical interleaving design methods into the paradigm of quantum turbo coding. Simulations results demonstrate that error floors in QTCs can be lowered significantly, while decreasing memory consumption, by proper interleaving design without increasing the overall decoding complexity of the system

A Doubly Orthogonal Matching Pursuit Algorithm for Sparse Predistortion of Power Amplifiers

This letter presents a new method for the digital predistortion (DPD) of power amplifiers (PAs) based on sparse behavioral models. The Gram-Schmidt orthogonalization is synergistically integrated into the orthogonal matching pursuit algorithm to decorrelate the selected model regressors against the components still to be selected. Experiments on a test bench based on a GaN PA driven by a 15-MHz orthogonal frequency division multiplexing signal were conducted in order to validate the algorithm. Experimental results in a DPD application and a comparison with other state-of-the-art algorithms highlight the enhancement of its pruning capabilities, reducing the number of coefficients while maintaining the performance.Comisión Interministerial de Ciencia y Tecnología (CICYT) TEC2014-53103-P TEC2017-82807-

Mineralogía y texturas del meteorito de Nulles (colección del M.N.C.N., Madrid)

The mineralogical and textural features of the Nulles meteorite are studied by opticall microscopy, SEM, and electrone microprobe. Olivine and plagioclase are the main primary phases of the silicate minerals, with the subsequent formation of epidote, from the oligoclase. The metallic phase consists of kamacite, taenite and troilite, with variable proportions of their Fe and Ni contents. The main textures reflect, apart of deformation, the existence of chondrules, intergrowths and seudomorphisms

El rol de la consistencia del mensaje y de la estrategia de marca en el capital de marca de un destino

La estrategia de comunicación seguida para difundir un destino turístico contribuye a su competitividad. El objetivo de esta investigación es conocer la importancia de la consistencia de los mensajes entre medios y de la estrategia de posicionamiento de marca en la difusión de un destino turístico. Con esta finalidad, se ha diseñado un experimento manipulando la consistencia del mensaje (alta consistencia vs baja consistencia de mensajes) y la estrategia de posicionamiento seguida por el destino (marca destino-único vs marca destino-múltiple). Los resultados obtenidos indican que la generación de una comunicación con mensajes altamente consistentes así como un posicionamiento basada en una estrategia de marca-única contribuyen a aumentar el Customer Based Destination Brand Equity. Además, se comprueba que el efecto de posicionamiento puede estar moderado por la consistencia de los mensajes a los que está expuesto el consumidor. Los resultados alcanzados suponen un avance en la literatura académica y una aportación para el sector profesional.A well-implemented communication strategy to raise the profile of a tourist destination contributes to its competitiveness. The aim of the present study is to understand the importance of message consistency across different media, and of the brand positioning strategy, in the promotion of a tourist destination. An experiment is conducted, manipulating (a) the degree of message consistency (high vs. low) and (b) the positioning strategy followed by the destination (sole-destination brand vs. multiple-destination brand). The results of the investigation suggest that communications based on highly consistent messages, and a sole-destination brand positioning strategy, contribute to increasing Customer-Based Destination Brand Equity. Further, the work demonstrates that the effect of positioning may be moderated by the degree of consistency between the messages to which the consumer is exposed. The findings represent a contribution to both the academic literature and to the professional sector.Ministerio de Economía y Competitividad ECO-2012-39217Junta de Andalucía P11 SEJ-810

Molecular and Clinical Predictors of Quality of Life in Chronic Rhinosinusitis with Nasal Polyps

Factors influencing the quality of life (QoL) of patients with chronic rhinosinusitis with nasal polyposis (CRSwNP) are poorly understood. We set out to determine the predictive factors on patients' QoL using the Sino-Nasal Outcome Test-22 (SNOT-22); (2) Methods: An ambispective analysis of data from patients diagnosed with CRSwNP in our institution. All the patients underwent a nasal polyp biopsy and completed the SNOT-22 questionnaire. Demographic and molecular data as well as the SNOT-22 scores were collected. Patients were classified in six subgroups considering the presence of asthma, non-steroidal drugs (NSAID) intolerance and corticosteroid resistance; (3) Results: The mean SNOT-22 score was 39. Considering the clinical parameters, the SNOT-22 value was significantly associated with NSAID intolerance (p = 0.04) and the endoscopic polyp score (p = 0.04). A high SNOT-22 value was also correlated with high tissue eosinophilia (p = 0.01) and high IL-8 expression; (4) Conclusions: Eosinophilia, IL-8 expression and NSAID intolerance can be used as predictors of worse QoL in patients with CRSwNP