Strict calculation of the light statistics at the output of a travelling wave optical amplifier

A new method for calculating the probability density function of the photon number propagating through a travelling wave optical amplifier with no restriction on its working regime (linear and nonlinear) is reported. The authors show that the widely used Gaussian approximation of the probability density function does not match the real statistics if the incident optical power is small.Peer ReviewedPostprint (published version

Practical method for modelling the nonlinear behaviour of a travelling wave semiconductor optical amplifier

The authors present a simple model of a travelling wave semiconductor optical amplifier with an appreciable degree of saturation. The model uses a particular way of linearising the total carrier recombination R(N) to find useful expressions for the saturation parameter and/or the carrier lifetime. By combining these expressions and the gain measurements realised, it is possible to establish the dependence between the mentioned parameters and the input optical power.Peer ReviewedPostprint (published version

ZipN is an essential FtsZ membrane tether and contributes to the septal localization of SepJ in the flamentous cyanobacterium Anabaena

The organismic unit of heterocyst-forming cyanobacteria is a filament of communicating cells connected by septal junctions, proteinaceous structures bridging the cytoplasms of contiguous cells. This distinct bacterial organization is preserved during cell division. In Anabaena, deletion of the zipN gene could not be segregated. We generated strain CSL109 that expresses zipN from a synthetic regulatable promoter. Under conditions of ZipN depletion, cells progressively enlarged, reflecting restricted cell division, and showed drastic morphological alterations including cell detachment from the filaments, to finish lysing. In contrast to the wild-type localization in midcell Z-rings, FtsZ was found in delocalized aggregates in strain CSL109. Consistently, the proportion of membrane-associated to soluble FtsZ in fractionated cell extracts was lower in CSL109. Bacterial two-hybrid analysis showed that ZipN interacts with FtsZ and other cell-division proteins including cytoplasmic Ftn6 and SepF, and polytopic FtsW, FtsX, FtsQ and FtsI. Additionally, ZipN interacted with the septal protein SepJ, and in CSL109 depletion of ZipN was concomitant with a progressive loss of septal specificity of SepJ. Thus, in Anabaena ZipN represents an essential FtsZ membrane tether and an organizer of the divisome, and it contributes to the conformation of septal structures for filament integrity and intercellular communication.Agencia Estatal de Investigación BFU2013-44686-P, BFU2016-77097-

Identificar cobertura vegetal de suelo clasificando pixeles en imágenes hiperepectrales con SVM (maquinas de soporte vectorial)

Se realizó un experimento para clasificar 4 clases de cobertura vegetal de suelo usando imágenes hiperespectrales, con 63 bandas. Se trabajó con un pixel representado por vector de 63 características (uno por banda). Se probaron nueve filtros y el análisis sin filtro. Para la clasificación se usó una máquina de soporte vectorial (SVM), con un kernel perceptor multicapa (MLP). Se obtienen precisiones aceptables, mejorando muchas encontradas en la literatura [1] [2]. Con este trabajo se demuestra que es mejor usar imágenes hiperespectrales que las comúnmente usadas. Los resultados sugieren que es necesario emplear otras técnicas o pre-proceso para mejorar las clasificaciones en este tipo de imágenes

How children and adults keep track of real information when thinking counterfactually

This research was funded by grants from the Spanish Government, Ministry of Economy and Competitiveness (PSI2015-63505-P; PGC2018095868-B-I00) to SM and the Education, Culture and Sport Ministry (FPU15/05899) to JG. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.We are very grateful to the schools for their assistance with data collection and to the directors, teachers and children for their cooperation. Finally, we wish to thank Ruth Byrne and Cristina Vargas for their helpful comments.Thinking about counterfactual conditionals such as “if she had not painted the sheet of paper, it would have been blank” requires us to consider what is conjectured (She did not paint and the sheet was blank) and what actually happened (She painted and the sheet was not blank). In two experiments with adults (Study 1) and schoolchildren from 7 to 13 years (Study 2), we tested three potential sources of difficulty with counterfactuals: inferring, distinguishing what is real vs conjectured (epistemic status) and comprehending linguistic conditional expressions (“if” vs “even if”). The results showed that neither adults nor schoolchildren had difficulty in the comprehension of counterfactual expressions such as “even if” with respect to “if then”. The ability to infer with both of these develops during school years, with adults showing great ability. However, the third source factor is critical: we found that the key to young children’s difficulty with counterfactual thinking was their inability to differentiate real and conjectured information, while adults showed little difficulty with this.Spanish Government, Ministry of Economy and Competitiveness PSI2015-63505-P PGC2018095868-B-I00Education, Culture and Sport Ministry FPU15/0589

Morphology-based automated baseline removal for raman spectra of artistic pigments

The interpretation of a Raman spectrum is based on the identification of its characteristic molecular bands. However, the assignment of the vibrational modes is often compromised by the presence in the spectrum of an intense fluorescence background that covers the measured spectra. Several techniques have been employed to minimize the presence of this fluorescence in order to resolve and analyze Raman spectra. In this paper a new automated method for fluorescence subtraction is described, based on morphology operations. This method is compared with the most commonly used polynomial fitting methods. Results indicate that the proposed automated method is efficient in fluorescence subtraction and retains the line shapes and positions of the Raman bands in the spectra.Postprint (published version

Caracterización estadística del amplificador óptico semiconductor aplicado en un enlace digital por fibra óptica

In this paper an statistical model for the semiconductor optical amplifier CSLA) working in linear regime is developped. This model, based on the STT theory, allows the calculation of any number of moments of the statistical distribution of photons of the amplified light. The validity of the model is shown using as input some different statistical distributions and evaluating their corresponding output distributions.Peer ReviewedPostprint (published version

Caracterización experimental de un amplificador optico de fibra dopada ER3+: Presentaciones en sistemas de transmisión coherente

In this communication we present an experimental characterization of an Er3+ -doped fiber amplifier. This kind of amplifier shows high gain and large bandwidth that can be very useful in improving performances of wide band coherent transmission systems . The resul ts obtained al so show good agreement with simulations of the theoretical model we have developed.Peer ReviewedPostprint (published version

Imaginary and war from New Babylon

La segunda guerra mundial y sus horrores, la promesa de la tecnología y la libertad marcaron el imaginario del artista holandés Constant Nieuwenhuys, creador de New Babylon, un proyecto cuya construcción estaría en manos de nómadas en una deriva constante, que sueñan, crean y hacen uso de la tecnología en una acción lúdica, colectiva y libre. New Babylon planteaba una nueva ciudad para el ciudadano del futuro, formalizando la idea situacionista del urbanismo unitario. El artículo expone las correspondencias entre el proyecto y las acciones de la guerra, entre el juego, la tecnología, las formas, lo colectivo y los mapas, para crear nuevas ciudades e inspirar a otros.The Second World War and its horrors, the promise of technology and freedom marked the imaginary of the Dutch artist Constant Nieuwenhuys, creator of New Babylon, a project whose construction would be in the hands of nomads in a constant drift, who dream, create and use the technology in a playful, collective and free action. New Babylon proposed a new city for the citizen of the future, formalizing the situationist idea of unitary urbanism. The article exposes the correspondences between the project and the actions of war, between the game, the technology, the forms, the collective and the maps, to create new cities and inspire others

Modelo estadístico del láser amplificador en un sistema de transmisión digital por fibra óptica monomodo

En este trabajo se obtiene un modelo estadístico del laser amplificador semiconductor y se desarrolla la metodología y el software necesarios para poder obtener resultados analíticos. En definitiva, se consigue conocer la estadística de la luz amplificada por este dispositivo de estado sólido. El número de momentos estadísticos que puede obtenerse depende, únicamente, de la capacidad del ordenador. Pueden entonces evaluarse, mediante la función densidad de probabilidad, el valor medio y la potencia de la información y del ruido cuántico a la salida del laser amplificador para poder analizar, finalmente, las prestaciones introducidas por el mismo en un enlace óptico.Peer ReviewedPostprint (published version