Caracterización y análisis de la señal climática en cronologías de Fagus sylvatica L. y Quercus robur L. en la región central de la Cornisa Cantábrica

In this work, the climatic responses of three beech (Fagus sylvatica L.) and three oak (Quercus robur L.) tree-ring chronologies in the central Cantabrian region, were analyzed. Regional temperature and precipitation data, and the climatic teleconnection indices of the North Atlantic Oscillation (NAO), were used as climatic predictors. Very similar interannual ring-width variability among chronologies of different species and localities was displayed. Chronologies of the same species and similar altitudes showed the highest cross-correlations, which were significant at widest timescales. Periodic signals of a variety of frequencies that coincided with signals characteristic of NAO indices, were discovered in the chronologies. Between 52 to 64% of growth variance was explained by regional climate, while 13 to 27% was related to monthly NAO indices. High summer temperatures in the year prior to ring formation and low winter temperatures limited beech growth at altitudes over 700 m. Oak radial growth at lower altitudes was limited by high spring temperatures in the previous year and summer drought in the year the ring was formed. Growth of both species displayed negative relationship with winter NAO indices, in the previous year for beech and in the current year for oak. Moreover, oak exhibited a negative correlation with NAO indices in the late summer of previous year. The obtained results suggest that more exhaustive research, regarding the characterization of radial growth and the analysis of its climatic response along the complete Cantabrian region, is required.En este trabajo se analizaron las respuestas climáticas de tres cronologías de haya (Fagus sylvatica L.) y tres de roble (Quercus robur L.) en la región central de la Cornisa Cantábrica. Se utilizaron datos climáticos regionales y el índice de Oscilación del Atlántico Norte (NAO) como indicativo de la señal macroclimática. Las cronologías presentaron una variabilidad interanual similar entre especies y localidades. Las correlaciones mayores y más extensas en el tiempo se obtuvieron entre cronologías de la misma especie y similar altitud. Las cronologías presentaron señales de distinta frecuencia coincidentes con señales características de los índices NAO. El 52-64% de la variación del crecimiento fue explicada por el clima regional, mientras que la NAO explicó un 13-27%. La elevada temperatura estival del año previo al crecimiento y la baja temperatura invernal fueron factores limitantes para el haya por encima de 700 m de altitud. El crecimiento del roble a baja altitud estuvo limitado por la elevada temperatura primaveral del año previo y por la sequía estival del año de crecimiento. Ambas especies mostraron una relación negativa con los índices NAO invernales, del año previo al crecimiento en el haya y del mismo año de crecimiento en el roble. En el roble se manifestó además una relación negativa con la NAO de final del verano del año previo. Estos resultados sugieren la necesidad de investigaciones más extensas sobre la caracterización del crecimiento radial y su respuesta climática a lo largo de la Cornisa Cantábrica

Cytocentrifugation as an additional method to study echinoderm coelomocytes: A comparative approach combining living cells, stained preparations, and energy-dispersive x-ray spectroscopy

Introduction: Echinoderm coelomocytes have traditionally been investigated through a morphological approach using light microscopy, which relies on the idea of constant cell shape as a stable character. However, this can be affected by biotic or abiotic conditions. Objective: To analyze if the consistency in cell morphology offered by the cytocentrifugation method, might be used as a convenient tool to study echinoderm coelomocytes. Methods: Cells of Echinaster (Othilia) brasiliensis (Asteroidea), Holothuria (Holothuria) tubulosa (Holothuroidea), Eucidaris tribuloides, Arbacia lixula, Lytechinus variegatus, and Echinometra lucunter (Echinoidea) were spread on microscope slides by cytocentrifugation, stained, and analyzed through light microscopy. Additionally, fluorescence microscopy, scanning electron microscopy, and energy-dispersive x-ray spectroscopy were applied to cytospin preparations, to complement the analysis of granular and colorless spherulocytes of Eucidaris tribuloides. Results: Altogether, 11 cell types, including phagocytes, spherulocytes, vibratile cells, and progeni-tor cells were identified in the samples analyzed. The granular spherulocyte, a newly-described cell type, was observed in all Echinoidea and was very similar to the acidophilic spherulocytes of Holothuria (Holothuria) tubulosa. Conclusions: Cytocentrifugation proved to be versatile, either as the main method of investigation in stained preparations, or as a framework on which other procedures may be performed. Its ability to maintain a constant morphology allowed accurate correspondence between live and fixed/stained cells, differentiation among similar spherulocytes as well as comparisons between similar cells of Holothuroidea and Echinoidea

Semi-Decoupled Second-Order Consistency Correction for Smoothed Particle Hydrodynamics

We present an approximate second-order consistent smoothed particle hydrodynamics method which uses the 1D solutions to approximate the 2D second order derivatives. The numerical tests of the analytic functions show that the method is exact for regular arrangements of interpolation points, while in the disordered areas the accuracy is lower than the exact solution of the second-order consistent modified smoothed particle hydrodynamics, but still better that the standard version or the so-called decoupled finite particle method. We applied the new model to the flow of a fluid around a circular solid obstacle and found that the use of a corrected semi-decoupled second-order consistent SPH gives better accuracy for lower resolutions allowing for a more efficient numerical model and also easier to extend to 3D

Goal-Oriented p-Adaptivity using Unconventional Error Representations for a 1D Steady State Convection-Diffusion Problem

This work proposes the use of an alternative error representation for Goal-Oriented Adaptivity (GOA) in context of steady state convection dominated diffusion problems. It introduces an arbitrary operator for the computation of the error of an alternative dual problem. From the new representation, we derive element-wise estimators to drive the adaptive algorithm. The method is applied to a one dimensional (1D) steady state convection dominated diffusion problem with homogeneous Dirichlet boundary conditions. This problem exhibits a boundary layer that produces a loss of numerical stability. The new error representation delivers sharper error bounds. When applied to a $p$-GOA Finite Element Method (FEM), the alternative error representation captures earlier the boundary layer, despite the existing spurious numerical oscillations.Basque Government Consolidated Research Group Grant IT649-13 Spanish Ministry under Grant No. FPDI- 2013-17098 ICERMAR Project KK-2015/0000097 CYTED 2011 project 712RT0449 FONDECYT project 116077

Crecimiento radial de las principales especies arbóreas de la isla de Cortegada (Parque Nacional de las Islas Atlánticas) en relación con la historia y el clima

Radial growth patterns of Quercus robur L., Quercus pyrenaicaWilld., Pinus pinaster Ait., Pinus pinea L. y Laurus nobilis L., the dominant tree species in the Cortegada island, Parque Nacional de la Islas Atlánticas de Galicia, were studied. The main objective was to determine the repercussion that land-use changes that occurred during the last century in the island, had on tree growth. The influence of the climatic variables mean monthly temperature and monthly precipitation on high frequency radial growth variation was also studied. The results show that the chronologies derived from all studied species reflect the succession of events that happened in the island in the XX century, with a gradual tree establishment along the first half of the century, a progressive canopy closure and the recent apparition of canopy gaps due to disturbances. The correlations between the climatic parameters and the year-to-year growth variations also reveal a higher tolerance of Q. pyrenaica and P. pinea to water shortage in spring and summer.Se realizó un estudio de los patrones de crecimiento radial de Quercus robur L., Quercus pyrenaica Willd., Pinus pinaster Ait., Pinus pinea L. y Laurus nobilis L., especies dominantes en la isla de Cortegada, perteneciente al Parque Nacional de las Islas Atlánticas de Galicia. El objetivo principal fue determinar la repercusión que han tenido sobre el crecimiento los cambios de uso del terreno ocurridos en el último siglo en la isla. También se estudió la influencia de algunas variables climáticas (temperatura media mensual y precipitación mensual) sobre las variaciones de alta frecuencia del crecimiento radial. Los resultados indican que las cronologías derivadas de todas las especies estudiadas reflejan la sucesión de acontecimientos acaecidos en la isla en el s. XX, con un gradual establecimiento del arbolado a lo largo de la primera mitad del siglo, un progresivo cierre del dosel y la reciente apertura de huecos en el mismo debido a perturbaciones. Las correlaciones obtenidas entre los parámetros climáticos y las variaciones interanuales del crecimiento manifiestan la mayor tolerancia de las especies Q. pyrenaica y P. pinea a la escasez de agua en los meses de primavera y verano

Goal-oriented adaptivity using unconventional error representations for the multi-dimensional Helmholtz equation

In goal‐oriented adaptivity, the error in the quantity of interest is represented using the error functions of the direct and adjoint problems. This error representation is subsequently bounded above by element‐wise error indicators that are used to drive optimal refinements. In this work, we propose to replace, in the error representation, the adjoint problem by an alternative operator. The main advantage of the proposed approach is that, when judiciously selecting such alternative operator, the corresponding upper bound of the error representation becomes sharper, leading to a more efficient goal‐oriented adaptivity. While the method can be applied to a variety of problems, we focus here on two‐ and three‐dimensional (2‐D and 3‐D) Helmholtz problems. We show via extensive numerical experimentation that the upper bounds provided by the alternative error representations are sharper than the classical ones and lead to a more robust p‐adaptive process. We also provide guidelines for finding operators delivering sharp error representation upper bounds. We further extend the results to a convection‐dominated diffusion problem as well as to problems with discontinuous material coefficients. Finally, we consider a sonic logging‐while‐drilling problem to illustrate the applicability of the proposed method.V. Darrigrand, A. Rodriguez-Rozas and D. Pardo were partially funded by the Projects of the Spanish Ministry of Economy and Competitiveness with reference MTM2013-40824-P, MTM2016-76329-R (AEI/FEDER, EU), MTM2016-81697-ERC and the Basque Government Consolidated Research Group Grant IT649- 13 on “Mathematical Modeling, Simulation, and Industrial Applications (M2SI)”. A. Rodriguez-Rozas and D.Pardo were also partially funded by the BCAM “Severo Ochoa” accreditation of excellence SEV-2013-0323 and the Basque Government through the BERC2014-2017 program. A. Rodriguez-Rozas acknowledges support from Spanish Ministry under Grant No. FPDI- 2013-17098. I. Muga was partially funded by the FONDECYT project 1160774. The first four authors were also partially funded by the European Union’s Horizon 2020, research and innovation program under the Marie Sklodowska-Curie grant agreement No 644202. Serge Prudhomme is grateful for the support by a Discovery Grant from the Natural Sciences and Engineering Research Council of Canada

Bcc crystal-fluid interfacial free energy in Yukawa systems

We determine the orientation-resolved interfacial free energy between a body-centered-cubic (bcc) crystal and the coexisting fluid for a many-particle system interacting via a Yukawa pair potential. For two different screening strengths, we compare results from molecular dynamics computer simulations, density functional theory, and a phase-field-crystal approach. Simulations predict an almost orientationally isotropic interfacial free energy of 0.12k B T/a 2 (with k B T denoting the thermal energy and a the mean interparticle spacing), which is independent of the screening strength. This value is in reasonable agreement with our Ramakrishnan-Yussouff density functional calculations, while a high-order fitted phase-field-crystal approach gives about 2−3 times higher interfacial free energies for the Yukawa system. Both field theory approaches also give a considerable anisotropy of the interfacial free energy. Our result implies that, in the Yukawa system, bcc crystal-fluid free energies are a factor of about 3 smaller than face-centered-cubic crystal-fluid free energies.Peer reviewe

Challenges and Technical Requirements for Integration of Renewable Energy Sources in Cuban Electric System

The decision of the Cuban Government to massively introduce Renewable Energy Sources (RES) as a way to change the energy matrix, and in particular, the electricity matrix, is presented as an opportunity to introduce not only sources of energy friendly with the environment, but also make the contributions that, without limiting the development of the country, respond to the UN Millennium Development Goals (UNMDG). However, the large-scale use of RESs in an electrical system such as Cuba, isolated and not interconnected to other systems, can have a group of challenges that must be taken into consideration when it is exploited, since it does not incorporate only new technologies, some of which depend on weather conditions such as solar, wind and hydro technology for the production of electricity, but allow us to think about the introduction of emerging technologies that can increase the penetration of RES in the electrical system and introduce new management concepts, both territorially and nationally. The present work reflects on this, from some experiences that have been analyzed in different research works carried out at CIPEL, plus other International experiences

Complicaciones a largo plazo de la parálisis cerebral espástica

Galería Fotográfica (sin resumen