1,211 research outputs found

    Darboux transformations for a Bogoyavlenskii equation in 2+1 dimensions

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    We use the singular manifold method to obtain the Lax pair, Darboux transformations and soliton solutions for a (2+1) dimensional integrable equation.Comment: 7 pages, latex, to appear in the proceedings of the meeting "Nonlinearity and Integrability" (Gallipoli, Italy, July 1999

    On the Design of a Novel Joint Network-Channel Coding Scheme for the Multiple Access Relay Channel

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    This paper proposes a novel joint non-binary network-channel code for the Time-Division Decode-and-Forward Multiple Access Relay Channel (TD-DF-MARC), where the relay linearly combines -- over a non-binary finite field -- the coded sequences from the source nodes. A method based on an EXIT chart analysis is derived for selecting the best coefficients of the linear combination. Moreover, it is shown that for different setups of the system, different coefficients should be chosen in order to improve the performance. This conclusion contrasts with previous works where a random selection was considered. Monte Carlo simulations show that the proposed scheme outperforms, in terms of its gap to the outage probabilities, the previously published joint network-channel coding approaches. Besides, this gain is achieved by using very short-length codewords, which makes the scheme particularly attractive for low-latency applications.Comment: 28 pages, 9 figures; Submitted to IEEE Journal on Selected Areas in Communications - Special Issue on Theories and Methods for Advanced Wireless Relays, 201

    Análisis de la utilización de antiulcerosos inhibidores de la bomba de protones en el área de atención primaria de la comarca Araba

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    OBJETIVO: Los antiulcerosos inhibidores de la bomba de protones (IBP) son uno de los grupos farmacologicos mas prescritos en atencion primaria. El objetivo del trabajo fue conocer la prescripcion de IBP en el Area de Atencion Primaria de la Comarca Araba de Osakidetza para sensibilizar a los medicos de familia sobre su correcta utilizacion, asi como fomentar la prescripcion de los IBP mas eficientes.METODOS: Estudio descriptivo de la prescripcion de IBP de 200 medicos de familia de la Comarca Araba de Osakidetza a partir de las recetas facturadas por las oficinas de farmacia durante los anos 2009-2014. Se analizo el importe del consumo y las Dosis por 1000 habitantes/dia (DHD) de IBP, asi como el consumo relativo de omeprazol respecto al resto de principios activos de este subgrupo terapeutico. El analisis estadistico se realizo mediante el programa IBM SPSS v23.RESULTADOS: La prescripcion de IBP se incremento un 23,75% (de 78,14 DHD en 2009 hasta 96,70 DHD en 2014), siendo su utilizacion muy superior a la de otros paises europeos. En el mismo periodo, el porcentaje de prescripcion relativa de omeprazol frente al resto de IBP disminuyo un 4,56% (el porcentaje de Dosis diaria definida (DDD) de omeprazol paso del 74,67% en 2009 al 70,11% en 2014). El gasto global de estos medicamentos disminuyo un 17,60%.CONCLUSIONES: Existe un incremento global en el numero de prescripciones de IBP, aunque ha disminuido el gasto por la reduccion de precios. Asimismo hay un descenso del consumo relativo de omeprazol, aunque no se han modificado las indicaciones aprobadas. La prescripcion de IBP debe realizarse con prudencia, ya que su elevado uso de forma injustificada en la prevencion de gastropatias aumenta el riesgo de prescripciones inadecuadas. El antiulceroso mas recomendado continua siendo el omeprAbstract OBJECTIVE: The proton pump inhibitors (PPI) anti-ulcer drugs are one of the most prescribed pharmacological groups in primary care. The objective of the work was to know the prescription of PPI in a Primary Care Area, the Araba district of the Basque Health Service, to advise family doctors about its correct use, and encourage the prescription of the most efficient PPIs. METHODS: Descriptive study of 200 family doctors PPI prescription at the Araba district of the Basque Health Service. Data were obtained from prescriptions billed by pharmacies between 2009 and 2014. We analyzed the expenses and DHD (DDD per 1000 inhabitants/day) of PPIs dispensed and the omeprazole relative uptake compared to other PPIs. Statistical analysis was performed with IBM SPSS v23 statistic software. RESULTS: IBP prescription increased by 23.75% (from 78.14 DHD in 2009 to 96.70 DHD in 2014). Their use was much higher than that of other European countries. In the same period, omeprazole relative prescription compared to other PPIs decreased by 4.56% (omeprazole % Defined daily dose (DDD) went from 74.67% in 2009 to 70.11% in 2014). The overall expenditure of these medicines decreased by 17.60%. CONCLUSIONS: There is an overall increase in the prescription of PPIs, although the expenses have decreased due to price drop. Likewise there is a decrease in the relative consumption of omeprazole, although the indications approved had not changed. PPIs prescription should be done with caution since their unjustified high use in the prevention of gastropathy increases the risk of inappropriate prescriptions. The most recommended PPI continues to be omeprazole

    Sensitivity enhancement of lossy mode resonance-based ethanol sensors by graphene oxide coatings

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    A layer by layer (LbL) coating made of polyethyleneimine (PEI) and graphene oxide (GO) is deposited onto an optical fiber ethanol sensor based on lossy mode resonances (LMR) in order to improve its response. The new sensor including the PEI/GO coating shows a better linearity and a sensitivity four times higher than the sensor without the coating. To our knowledge, this is the first time that a LbL coating made of PEI and GO is included in an optical fiber sensor based on LMR

    An on-line VAD based on Multi-Normalisation Scoring (MNS) of observation likelihoods

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    Preprint del artículo públicado online el 31 de mayo 2018Voice activity detection (VAD) is an essential task in expert systems that rely on oral interfaces. The VAD module detects the presence of human speech and separates speech segments from silences and non-speech noises. The most popular current on-line VAD systems are based on adaptive parameters which seek to cope with varying channel and noise conditions. The main disadvantages of this approach are the need for some initialisation time to properly adjust the parameters to the incoming signal and uncertain performance in the case of poor estimation of the initial parameters. In this paper we propose a novel on-line VAD based only on previous training which does not introduce any delay. The technique is based on a strategy that we have called Multi-Normalisation Scoring (MNS). It consists of obtaining a vector of multiple observation likelihood scores from normalised mel-cepstral coefficients previously computed from different databases. A classifier is then used to label the incoming observation likelihood vector. Encouraging results have been obtained with a Multi-Layer Perceptron (MLP). This technique can generalise for unseen noise levels and types. A validation experiment with two current standard ITU-T VAD algorithms demonstrates the good performance of the method. Indeed, lower classification error rates are obtained for non-speech frames, while results for speech frames are similar.This work was partially supported by the EU (ERDF) under grant TEC2015-67163-C2-1-R (RESTORE) (MINECO/ERDF, EU) and by the Basque Government under grant KK-2017/00043 (BerbaOla)

    Graphene Oxide in Lossy Mode Resonance-Based Optical Fiber Sensors for Ethanol Detection

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    The influence of graphene oxide (GO) over the features of an optical fiber ethanol sensor based on lossy mode resonances (LMR) has been studied in this work. Four different sensors were built with this aim, each comprising a multimode optical fiber core fragment coated with a SnO2 thin film. Layer by layer (LbL) coatings made of 1, 2 and 4 bilayers of polyethyleneimine (PEI) and graphene oxide were deposited onto three of these devices and their behavior as aqueous ethanol sensors was characterized and compared with the sensor without GO. The sensors with GO showed much better performance with a maximum sensitivity enhancement of 176% with respect to the sensor without GO. To our knowledge, this is the first time that GO has been used to make an optical fiber sensor based on LMR

    Lossy Mode Resonance Generation by Graphene Oxide Coatings onto Cladding-Removed Multimode Optical Fiber

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    In this work, we have studied the suitability of graphene oxide-based thin films to be not only excellent sensitive coatings but also lossy mode resonance (LMR)-generating materials. Thin films of graphene oxide (GO) and polyethylenimine (PEI) fabricated by means of layer-by-layer assembly were selected in this study. Two optical fiber devices with 8 and 20 bilayers of the LMR-generating coating were fabricated and characterized as refractometers. Both devices show no hysteresis and high sensitivity, improving previously reported values. This research opens very promising and exciting possibilities in the field of optical fiber sensors based on LMR, strategically including specific recognition groups to the device surface to exploit this high sensitivity for monitoring a range of target analytes. The carboxylate functional groups at the edges of the GO sheets should provide excellent attachment sites for the required coupling chemistry to realize such devices

    RESTORE Project: REpair, STOrage and REhabilitation of speech

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    RESTORE is a project aimed to improve the quality of commu-nication for people with difficulties producing speech, provid-ing them with tools and alternative communication services. Atthe same time, progress will be made at the research of tech-niques for restoration and rehabilitation of disordered speech.The ultimate goal of the project is to offer new possibilities inthe rehabilitation and reintegration into society of patients withspeech pathologies, especially those laryngectomised, by de-signing new intervention strategies aimed to favour their com-munication with the environment and ultimately increase theirquality of life.This project has been founded by the Spanish Ministry of Economy and Competitiveness with FEDER support (RESTOREproject, TEC2015-67163-C2-1-R and TEC2015-67163-C2-2-R
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