Stokes polarimeters based on Liquid Crystals

Tesina final de master realitzada en col.laboració amb el Departament de Física, Universitat Autònoma de BarcelonaMàster oficial realitzat en col·laboració amb Universitat Autònoma de Barcelona (UAB), Universitat de Barcelona (UB) i Institut de Ciències Fotòniques (ICFO)In this work, we present a study of different Stokes polarimeters where liquid crystal devices are fundamental elements of the design. These anisotropic materials act as variable retarders controlled electronically. Therefore, it leads to a versatile setup where an optimization of some parameters of the design is essential to minimize the noise propagation. On the one hand, a polarimeter based on two parallel aligned liquid crystal is proposed. Since we can perform any polarization analyzer with this system, we achieve as optimal configuration a set of four analyzers with equispaced distribution in the Poincaré sphere, forming a regular tetrahedron. On the other hand, we analyze a second polarimeter formed by one twisted nematic liquid crystal. Although the optimum configuration is limited by the characteristic curve, we achieve a well-conditioned system with a simpler design. Once the design optimization is done, we carry out an experimental calibration to know exactly the real polarization analyzers used in the laboratory. Finally, we test and compare the two implemented polarimeters and their results are verified with a commercial Stokes polarimete

El urbanismo comercial

Treball Final de Grau en Dret. Codi: DR1052. Curs acadèmic 2013/201

Genomic Instability in Newborn with Short Telomeres

Telomere length is considered to be a risk factor in adults due to its proved association with cancer incidence and mortality. Since newborn present a wide interindividual variation in mean telomere length, it is relevant to demonstrate if these differences in length can act also as an early risk indicator. To answer this question, we have measured the mean telomere length of 74 samples of cord blood from newborns and studied its association with the basal genetic damage, measured as the frequency of binucleated cells carrying micronuclei. In addition, we have challenged the cells of a subgroup of individuals (N = 35) against mitomycin-C (MMC) to establish their sensitivity to induced genomic instability. Results indicate that newborn with shorter telomeres present significantly higher levels of genetic damage when compared to those with longer telomeres. In addition, the cellular response to MMC was also significantly higher among those samples from subjects with shorter telomeres. Independently of the causal mechanisms involved, our results show for the first time that telomere length at delivery influence both the basal and induced genetic damage of the individual

Del código técnico de la edificación al estándar Passivhaus. Análisis de la envolvente de una vivienda unifamiliar

Este trabajo surge por el interés y la importancia que hoy en día tiene la eficiencia energética en todos los ámbitos y fundamentalmente en el de la construcción, el cual supone en Europa un 40% de su consumo energético total. Por esta razón, nuestra profesión tiene un papel muy importante en las estrategias de ahorro de energía.Se propone conocer el Código Técnico de la Edificación, que es la normativa de ahorro de energía vigente en España y el estándar de certificación energética internacional Passivhaus, que nace en Alemania. A través de un ejemplo práctico de un caso real, se investigan los indicadores que componen cada norma para poder hacer una comparación contrastada que nos ayude a comprender las estrategias que se están siguiendo en la actualidad.<br /

Acquisition et renseignement de l’indicateur espèces thermophobes: État des populations de la gorgone blanche Eunicella singularis dans le Parc national de Port-Cros dans le cadre de OBi_1. (2016). Rapport final. Contrat Parc national de Port-Cros & Universitat de Barcelona

Étude réalisée par l’Universitat de Barcelona, dans le cadre d’un Partenariat Scientifique avec le Parc National de Port-Cros. Contrat n°: 16-010 - 83400 P

Clinical validation of eye vergence as an objective marker for diagnosis of ADHD in children

Objective: ADHD youth show poor oculomotor control. Recent research shows that attention-related eye vergence is weak in ADHD children. Method: To validate vergence as a marker to classify ADHD, we assessed the modulation in the angle of vergence of children (n = 43) previously diagnosed with ADHD while performing an attention task and compared the results with age-matched clinical controls (n = 19) and healthy peers (n = 30). Results: We observed strong vergence responses in healthy participants and weak vergence in the clinical controls. ADHD children showed no significant vergence responses. Machine-learning models classified ADHD patients (n = 21) from healthy controls (n = 21) with an accuracy of 96.3% (false positive [FP]: 5.12%; false negative [FN]: 0%; area under the curve [AUC]: 0.99) and ADHD children (n = 11) from clinical controls (n = 14) with an accuracy of 85.7% (FP: 4.5%; FN: 19.2%, AUC: 0.90). Conclusion: In combination with an attention task, vergence responses can be used as an objective marker to detect ADHD in children.Peer ReviewedPostprint (author's final draft

Graphene Reflectarray Metasurface for Terahertz Beam Steering and Phase Modulation

We report a THz reflectarray metasurface which uses graphene as active element to achieve beam steering, shaping and broadband phase modulation. This is based on the creation of a voltage controlled reconfigurable phase hologram, which can impart different reflection angles and phases to an incident beam, replacing bulky and fragile rotating mirrors used for terahertz imaging. This can also find applications in other regions of the electromagnetic spectrum, paving the way to versatile optical devices including light radars, adaptive optics, electro-optical modulators and screens

Long-term monitoring of temperate macroalgal assemblages inside and outside a No take marine reserve

Macroalgal communities have an essential role in the shallow benthic habitats of temperate seas, where changes in their composition can resonate through entire coastal ecosystems. As all major ecosystems on Earth, algal beds have already been affected by multiple disturbances. Passive conservation tools, such as marine protected areas or No-take zones, have the potential to reduce some of the anthropogenic impacts by limiting human activity. However, without a good knowledge of the natural community dynamics, it is not easy to discern between changes fruit of the intrinsic variability of biological communities and the ones caused by human-related stressors. In this study, we evaluated the natural variability of macroalgal communities' composition inside and outside a Mediterranean No-Take marine reserve during 15 years. We described their temporal dynamics considering their main drivers and we tested the effect of protection in seaweed beds. We did not find differences either in the composition of the macroalgal assemblages or the total algal cover between protected and nonprotected locations over the fifteen years of study. Nevertheless, we observed a positive effect of the protection increasing the cover of some specific species, such as the canopy-forming Treptacantha elegans. Our results highlight the importance of obtaining long-term data in ecological studies to better understand the natural variability of marine communities. Accordingly, a robust understanding of the community dynamics would help us to avoid misinterpretations between 'impacted' or 'in-recovery' communities when recovery times are longer than the study periods