Tourmaline 40Ar/39Ar chronology of tourmaline-rich rocks from Central Iberia dates the main Variscan deformation phases

During crustal thickening, metapelites taken to depth release boron-bearing hydrothermal fluids because of progressive heating and dehydration. These fluids swiftly percolate upwards, especially if the crust is being actively deformed, to form tourmaline where the PT conditions and the chemical composition of the host-rock are favorable. The age of the so-formed tourmaline would record the age of the upward admittance of B-bearing fluids and, presumably, the age of the deformation. This process has been documented in the Martinamor Antiform of Central Iberia, a region where tourmaline-bearing rocks are particularly abundant. Metasomatic tourmaline from the Late Cambrian San Pelayo orthogneisses (zircon U-Pb age of 496 ± 5 Ma) yielded 40Ar/39Ar plateau ages at 370 ± 5 Ma and 342 ± 5 Ma. The first value represents the crystallization age of the tourmaline and is so far the most precise estimation of the age of crustal thickening in Central Iberia (D1). The second value reflects a partial loss of Ar caused by the second deformation phase (D2). Tourmaline from mylonitized and folded tourmalinites developed above D2 shear zones yield perturbed spectra with mean "plateau" ages of 347 ± 9 Ma and 342 ± 9 Ma which may represent either the resetting of older tourmaline or the formation of new tourmaline by focused boron metasomatism. After the metamorphic peak and simultaneously with the emplacement of the main granitoids of the Avila Batholith (310-315 Ma), another episode of boron metasomatism precipitated a new generation of tourmaline, which appears either concentrated in fine-layered tourmalinites (318 ± 2 Ma) or disseminated within Ediacaran-Cambrian metasediments (316 ± 2 Ma). The source of boron was the breakdown of previously formed tourmaline during melting reactions. Lastly, tourmaline from a leucogranitic body yielded a saddle-shaped age spectrum with a minimum age of ca. 296 Ma, roughly coeval with the youngest leucograni - tes. Although further work is required, our results suggest that tourmaline can be a useful chronological marker for dating deformation and magmatism

A white dwarf catalogue from Gaia-DR2 and the Virtual Observatory

We present a catalogue of 73¿221 white dwarf candidates extracted from the astrometric and photometric data of the recently published Gaia-DR2 catalogue. White dwarfs were selected from the Gaia Hertzsprung–Russell diagram with the aid of the most updated population synthesis simulator. Our analysis shows that Gaia has virtually identified all white dwarfs within 100¿pc from the Sun. Hence, our sub-population of 8555 white dwarfs within this distance limit and the colour range considered, -0.52<(GBP-GRP)<0.80¿, is the largest and most complete volume-limited sample of such objects to date. From this sub-sample, we identified 8343 CO-core and 212 ONe-core white dwarf candidates and derived a white dwarf space density of 4.9±0.4×10-3pc-3¿. A bifurcation in the Hertzsprung–Russell diagram for these sources, which our models do not predict, is clearly visible. We used the Virtual Observatory SED Analyzer tool to derive effective temperatures and luminosities for our sources by fitting their spectral energy distributions, that we built from the ultraviolet to the near-infrared using publicly available photometry through the Virtual Observatory. From these parameters, we derived the white dwarf radii. Interpolating the radii and effective temperatures in hydrogen-rich white dwarf cooling sequences, we derived the surface gravities and masses. The Gaia 100¿pc white dwarf population is clearly dominated by cool (~8000¿K) objects and reveals a significant population of massive (¿M~0.8M¿¿) white dwarfs, of which no more than ~30--40 per cent can be attributed to hydrogen-deficient atmospheres, and whose origin remains uncertain.Peer ReviewedPreprin

Object classification using bimodal perception data extracted from single-touch robotic grasps

[ES] Este trabajo presenta un método para clasificar objetos agarrados con una mano robótica multidedo combinando en un descriptor híbrido datos propioceptivos y táctiles. Los datos propioceptivos se obtienen a partir de las posiciones articulares de la mano y los táctiles se extraen del contacto registrado por células de presión instaladas en las falanges. La aproximación propuesta permite identificar el objeto aprendiendo de forma implícita su geometría y rigidez usando los datos que facilitan los sensores. En este trabajo demostramos que el uso de datos bimodales con técnicas de aprendizaje supervisado mejora la tasa de reconocimiento. En la experimentación, se han llevado a cabo más de 3000 agarres de hasta 7 objetos domésticos distintos, obteniendo clasificaciones correctas del 95%con métrica F1, realizando una única palpación del objeto. Además, la generalización del método se ha verificado entrenando nuestro sistema con unos objetos y posteriormente, clasificando otros nuevos similar[EN] This work presents a method to classify grasped objects with a multi-fingered robotic hand combining proprioceptive and tactile data in a hybrid descriptor. The proprioceptive data are obtained from the joint positions of the hand and the tactile data are obtained from the contact registered by pressure cells installed on the phalanges. The proposed approach allows us to identify the grasped object by learning the contact geometry and stiness from the readings by sensors. In this work, we show that using bimodal data of different nature along with supervised learning techniques improves the recognition rate. In experimentation, more than 3000 grasps of up to 7 dierent domestic objects have been carried out, obtaining an average F1 score around 95 %, performing just a single grasp. In addition, the generalization of the method has been verified by training our system with certain objects and classifying new, similar ones without any prior knowledge.Este trabajo ha sido financiado con Fondos Europeos de Desarrollo Regional (FEDER), Ministerio de Economía, Industria y Competitividad a través del proyecto DPI2015-68087-R y la ayuda pre-doctoral BES-2016-078290, y también gracias al apoyo de la Comisión Europea y del programa Interreg V. Sudoe a través del proyecto SOE2/P1/F0638.Velasco, E.; Zapata-Impata, B.; Gil, P.; Torres, F. (2020). Clasificación de objetos usando percepción bimodal de palpación única en acciones de agarre robótico. Revista Iberoamericana de Automática e Informática industrial. 17(1):44-55. https://doi.org/10.4995/riai.2019.10923OJS4455171Bae, J., Park, S., Park, J., Baeg, M., Kim, D., Oh, S., Oct 2012. Development of a low cost anthropomorphic robot hand with high capability. 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Revista Iberoamericana de Automática e Informática Industrial 14 (1), 104-114. https://doi.org/10.1016/j.riai.2016.09.005Delgado, A., Corrales, J., Mezouar, Y., Lequievre, L., Jara, C., Torres, F., 2017. Tactile control based on gaussian images and its application in bi-manual manipulation of deformable objects. Robotics and Autonomous Systems 94, 148 - 161. https://doi.org/10.1016/j.robot.2017.04.017Glorot, X., Bordes, A., Bengio, Y., 11-13 Apr 2011. Deep sparse rectifier neural networks. In: Gordon, G., Dunson, D., Dudík, M. (Eds.), Proceedings of the Fourteenth International Conference on Artificial Intelligence and Statistics. Vol. 15 of Proceedings of Machine Learning Research. PMLR, Fort Lauderdale, FL, USA, pp. 315-323. URL: http://proceedings.mlr.press/v15/glorot11a.htmlGuo, D., Kong, T., Sun, F., Liu, H., May 2016. Object discovery and grasp detection with a shared convolutional neural network. 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In: 32nd International Conference on International Conference on Machine Learning. Vol. 15. JMLR, pp. 448-456.Kang, L., Ye, P., Li, Y., Doermann, D., June 2014. Convolutional neural networks for no-reference image quality assessment. In: 2014 IEEE Conference on Computer Vision and Pattern Recognition. pp. 1733-1740. https://doi.org/10.1109/CVPR.2014.224Kohavi, R., 1995. A study of cross-validation and bootstrap for accuracy estimation and model selection. In: Proceedings of the 14th International Joint Conference on Artificial Intelligence - Volume 2. IJCAI'95. Morgan Kaufmann Publishers Inc., San Francisco, CA, USA, pp. 1137-1143. URL: http://dl.acm.org/citation.cfm?id=1643031.1643047Krizhevsky, A., Sutskever, I., Hinton, G. E., 2012. Imagenet classification with deep convolutional neural networks. In: Proceedings of the 25th International Conference on Neural Information Processing Systems - Volume 1. NIPS'12. Curran Associates Inc., USA, pp. 1097-1105. 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Ros: an open-source robot operating system. In: IEEE International Conference on Robotics and Automation (ICRA): Workshop on Open Source Software. URL: http://www.willowgarage.com/papers/ros-open-source-robot-operating-systemReinecke, J., Dietrich, A., Schmidt, F., Chalon, M., May 2014. Experimental comparison of slip detection strategies by tactile sensing with the biotac on the dlr hand arm system. In: IEEE International Conference on Robotics and Automation (ICRA). pp. 2742-2748. https://doi.org/10.1109/ICRA.2014.6907252Rispal, S., Rana, A. K., Duchaine, V., 2017. Texture roughness estimation using dynamic tactile sensing. 2017 3rd International Conference on Control, Automation and Robotics, ICCAR 2017, 555-562. https://doi.org/10.1109/ICCAR.2017.7942759Sanchez, J., Corrales, J.-A., Bouzgarrou, B.-C., Mezouar, Y., 2018. Robotic manipulation and sensing of deformable objects in domestic and industrial applications: a survey. 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Infrared-excess white dwarfs in the Gaia 100 pc sample

We analyse the 100¿pc Gaia white dwarf volume-limited sample by means of VOSA (Virtual Observatory SED Analyser) with the aim of identifying candidates for displaying infrared excesses. Our search focuses on the study of the spectral energy distribution (SED) of 3733 white dwarfs with reliable infrared photometry and GBP - GRP colours below 0.8 mag, a sample that seems to be nearly representative of the overall white dwarf population. Our search results in 77 selected candidates, 52 of which are new identifications. For each target, we apply a two-component SED fitting implemented in VOSA to derive the effective temperatures of both the white dwarf and the object causing the excess. We calculate a fraction of infrared-excess white dwarfs due to the presence of a circumstellar disc of 1.6 ± 0.2 per¿cent, a value that increases to 2.6 ± 0.3 per¿cent if we take into account incompleteness issues. Our results are in agreement with the drop in the percentage of infrared excess detections for cool (20¿000¿K) white dwarfs obtained in previous analyses. The fraction of white dwarfs with brown dwarf companions we derive is ¿0.1–0.2 per¿cent.Peer ReviewedPostprint (author's final draft

Searching for a Leptophilic Z' and a 3-3-1 symmetry at CLIC

We derive the discovery potential of a leptophilic Z', and a Z' rising from a $SU(3) \times SU(3)_L \times U(1)_N$ symmetry at the Compact Linear Collider (CLIC), which is planned to host $e^+e^-$ collisions with 3 TeV center-of-mass energy. We perform an optimized selection cut strategy on the transverse momentum, pseudorapidity, and invariant mass of the dileptons in order to enhance the collider sensitivity. We find that CLIC can potentially reach a $5\sigma$ signal of a $1-3$~TeV leptophilic Z' with less than $1fb^{-1}$ of integrated luminosity. As for the Z' belonging to a 3-3-1 symmetry, CLIC will offer a complementary probe with the potential to impose $M_{Z^\prime} > 3$~TeV with $\mathcal{L}=2fb^{-1}$.Comment: 8 pages, 4 figure

Reflection and transmission of waves in surface-disordered waveguides

The reflection and transmission amplitudes of waves in disordered multimode waveguides are studied by means of numerical simulations based on the invariant embedding equations. In particular, we analyze the influence of surface-type disorder on the behavior of the ensemble average and fluctuations of the reflection and transmission coefficients, reflectance, transmittance, and conductance. Our results show anomalous effects stemming from the combination of mode dispersion and rough surface scattering: For a given waveguide length, the larger the mode transverse momentum is, the more strongly is the mode scattered. These effects manifest themselves in the mode selectivity of the transmission coefficients, anomalous backscattering enhancement, and speckle pattern both in reflection and transmission, reflectance and transmittance, and also in the conductance and its universal fluctuations. It is shown that, in contrast to volume impurities, surface scattering in quasi-one-dimensional structures (waveguides) gives rise to the coexistence of the ballistic, diffusive, and localized regimes within the same sample.Comment: LaTeX (REVTeX), 12 pages with 14 EPS figures (epsf macro), minor change

Improving detection of surface discontinuities in visual-force control systms

In this paper, a new approach to detect surface discontinuities in a visual–force control task is described. A task which consists in tracking a surface using visual–force information is shown. In this task, in order to reposition the robot tool with respect to the surface it is necessary to determine the surface discontinuities. This paper describes a new method to detect surface discontinuities employing sensorial information obtained from a force sensor, a camera and structured light. This method has proved to be more robust than previous systems even in situations where high frictions occur