“… al estilo de Inglaterra según la última moda”. Figurines ingleses. Edición para España 1824-25 de Rudolph Ackermann

Desde el último tercio del siglo XVIII, las estampas de figurines relacionadas directamente con la apariencia, el gusto y la moda, difundidas desde la prensa, tienen en España una especial significación a la hora de orientar a las élites urbanas e ilustradas. Se trataba, en definitiva, de estar al día de las novedades y adelantos que se producían en todos aquellos objetos y elementos destinados a priorizar el estatus y la elegancia conforme a los dictados que se gestaban en las grandes capitales europeas que marcaban las pautas de la distinción. Londres y lo inglés, junto a los figurines parisinos, comenzó a formar parte de los criterios estéticos de la alta sociedad española, que participó a través de la elección de lo británico como símbolo de una nueva modernidad. Buen ejemplo de ello es el volumen de grabados, editados por la Casa Ackermann, bajo el título Figurines ingleses. Edición para España 1824-25, que se analiza en este estudio

Discriminant ability for caries risk of modified colorimetric tests

Objetive: The aim of this study was to evaluate the relationship between the caries risk in children over a two-year period and their baseline caries status, salivary levels of mutans streptococci and lactobacilli, and results of the Alban test and modifications thereof using different substrates. Study design: Ninety-five children aged 6-7 were examined in Granada (southern Spain) for dental caries at baseline and every six months. Stimulated saliva was sampled and inoculated in 7 colorimetric tests based on Snyder's medium with different sugars and polyalcohols. A mutans streptococci and lactobacilli count was performed (Dentocult SM strip® and Dentocult LB®). Caries risk proportions were contrasted against the potential predictor variables, i.e., basal caries history and salivary tests, by means of the Mantel Haenszel test for linear association, based on a chi-square distribution with 1 degree of freedom (df). Results: Caries index, lactobacillus count and colorimetric tests showed significant, but limited, and non-different discriminant abilities. Increasing values of all predictor variables, except for Dentocult SM®, were related to increasing caries risk proportions. Conclusion: Colorimetric test results and caries history showed similar correlation values as caries predictors. © Medicina Oral S. L

Broadband 1x2 liquid crystal optical switch with low thermal dependence

The proceeding at: 22nd International Conference on Plastic Optical Fibers (POF 2013), took place in 2013 September,11-13, in Armação dos Buzios, Rio de Janeiro, (Brasil). The event Web site at: http://www.pof2013.org.br/ .In this work, the optimized design of a broadband 1×2 liquid crystal (LC) optical switch (OS) is presented. The design is based on a polarization rotator (PR), which is composed of two nematic LC cells. The azimuth angle and thickness of each LC cell is obtained with a simple computational optimization approach, with performance comparable with more complex existing procedures. The LC-OS is capable to route, in a uniform way, optical signals in the visible spectral range (400 nm - 700 nm) with low thermal dependence in the range from 15ºC to 40ºC, making it ideal for wavelength division multiplexing applications in POF systems.This work has been sponsored by the Spanish Economy and Education Ministries through grants (Ref. TEC2012-37983-C03-02 and Ref. PRX12/00007).Publicad

Continuous Measurement With Three-in-One Plasmon Sensor in Sucrose Solutions

Surface plasmons are a revolution in nanophotonics because they permit the transport of energy along metal-dielectric interfaces, something which is of vital importance in sensorswhichmeasure refractive indexes. The aim of this research has been the design and optimization of several surface plasmon resonance (SPR) sensors to measure the refractive index of a solution of sucrose and water (BRIX degree) in real time. The optimization and design of these sensors was made from the theoretical modelling of the reflectance curves, which has allowed us to determine which the most favourable configuration is. The sensors proposed are modulated in intensity and they have the advantage of not having mobile parts, so, their lifetime is longer.We propose a plasmonic sensors (three-in-one) formeasuring different sucrose concentrations.As the refractive indexes vary very little with the concentration, we have designed a three-in-one sensor to cover all concentrations from 0-80% BRIX degree. The proposed sensors operate by ranges of refractive indexes (low, medium and high). They are made up of a hemispherical prism and a layer of gold following the Kretschmann configuration. The sensor working in the low zone has a sensitivity of between 22.95 and 4.64RIU−1 and a resolution of between 4.3 × 10−4 and 8.7 × 10−5RIU, the one used for the medium zone has a sensitivity of between 21.05 and 3.89RIU−1 and a resolution of between 5.1 × 10−4 and 9.5 × 10−5RIU, and the one for the high zone has a sensitivity of between 19.60 and 4.64RIU−1 and a resolution of between 4.3 × 10−4 and 1.0 × 10−4RIU

Optimization of polarization rotators spectral response for broadband optical switching applications

La ponencia se presentó en: VIII Reunión Española de Optoelectrónica OPTOEL’13 , celebrado los días 10-12 de Julio de 2013, lugar de celebración Alcalá de Henares (España).In this work, optimized designs of broadband polarization rotators based on cascaded nematic liquid crystal cells are presented. Visible spectral range (400 nm – 700 nm) is considered in the designs. A simple computational optimization approach, with performance comparable with more complex existing procedures, is used. Application of designed achromatic polarization rotators in the implementation of optical switches for wavelength division multiplexing in polymer optical fibers networks is also analyzed.This work has been sponsored by the Spanish CICYT (grant nº.TEC2012-37983-C03-02) and CAM (grant.nº. S2009/ESP-1781).Publicad

Synthesis of Asymmetric Flat-Top Birefringent Interleaver Based on Digital Filter Design and Genetic Algorithm

A flexible and fast synthesis method for designing asymmetric interleavers with flat-top, low dispersion, adjustable isolation, and bandwidths at both outputs is proposed. Interleavers are designed on birefringent technology allowing linear-phase designs. Z-transform properties and digital filter design techniques are used for designing interleavers under a set of specifications. At a second level, a genetic algorithm optimization approach allows improving the interleaver design adjusting the minimum isolation, at both outputs, below -43 dB and the stop bandwidths to specific normalized values of ±0.15 and ±0.3, with zero dispersion at one output. Improvement of the interleaver order and dispersion below ±50 ps/nm at both outputs are also reported.This work was partially supported in part by the Spanish CICYT under Grants TEC2009-14718-C03-03 and TEC2012-37983-C03-02 and in part by CAM under Grant S2009/ESP-1781.Publicad

Broadband 1×2 liquid crystal router with low thermal dependence for polymer optical fiber networks

A 1×2 optical router based on an achromatic liquid crystal polarization rotator has been designed and experimentally tested. The router can work in the spectral range used in step-index polymer optical fiber networks (400-700 nm) with low wavelength and temperature dependences. The theoretical design is fast and simple and has good agreement with experimental results. Experimental crosstalk is lower than -18.68 dB for both outputs, even with thermal variations of 10 °C. Performance improvement with respect to previously reported devices with similar structure has also been analyzed.This paper was supported by the Spanish Economy and Education Ministries through grants (Refs.TEC2012-37983-C03-02 and PRX12/00007).Publicad

Spectral method for fast measurement of twisted nematic liquid crystal cell parameters

We present an experimental approach for the fast measurement of twisted nematic (TN) liquid crystal (LC) cells' parameters. It is based on the spectral measurements of the light transmitted by the system polarizer-reference wave plate-LC cell-analyzer. The cell parameters are obtained by fitting the theoretical model to the experimental data. This method allows determining the rubbing angle, the twist angle and its sense, and the spectral dispersion of the LC cell retardation, simultaneously, with few measurements and without the need of applying voltage or any specific analytical conditions. The method is validated by characterizing two different TN cells with retardations of about 0.91 and 1.85 mum. The birefringence relative error is less than 1.3%.This work was supported in part by the Ministerio de Economía y Competitividad of Spain under Grant TEC2012–37983–C03–02Publicad

INVESTIGACIÓN ACADÉMICA Y TRANSFERENCIA DE CONOCIMIENTO SOBRE COMPUTACIÓN GRID EN LA “UNIVERSIDAD DISTRITAL - FRANCISCO JOSÉ DE CALDAS”

Este artículo presenta experiencias innovadoras en el ámbito nacional, resultado de la preparación e realización de un  curso  en  Sistemas  de  Información  Avanzados  para  Ciencia  con base en computación grid (mallas computacionales). A  tal efecto, se concibió, diseñó e implementó una malla computacional de propósito específico, con base en GlobusTool- kit 4, una red ad hoc, una infraestructura virtual y un modelo  pedagógico avanzado apoyado en conceptos constructivistas  y de aprendizaje virtual cooperativo

Reconfigurable 1 x 2 wavelength selective switch using high birefringence nematic liquid crystals

This paper was published in Applied Optics and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/AO.51.005960 Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.A reconfigurable 1 x 2 wavelength selective switch, based on a Lyot filter and high birefringence nematic liquid crystals, is proposed. Simulations and experimental results of a reconfigurable switch are reported. Insertion losses from 3.4 dB and rejection ratios up to 15 dB are obtained in a two input channel system at 560 and 621 nm. Control voltages of 0 to 3 VRMS are used.This work was partially supported by the Spanish CICYT (grant No. TEC2009-14718-C03-03) and CAM (grant No. S2009/ESP-1781).Publicad