Efflux of Osmolyte Amino Acids during Isovolumic Regulation in Hippocampal Slices

The efflux of potassium (K+) and amino acids from hippocampal slices was measured after sudden exposure to 10% (270 mOsm), 25% (225 mOsm) or 50% (150 mOsm) hyposmotic solutions or after gradual decrease (22.5 mOsm/min) in external osmolarity. In slices suddenly exposed to 50% hyposmotic solutions, swelling was followed by partial (74%) cell volume recovery, suggesting regulatory volume decrease (RVD). With gradual hyposmotic changes, no increase in cell water content was observed even when the solution at the end of the experiment was 50% hyposmotic, showing the occurrence of isovolumic regulation (IVR). The gradual decrease in osmolarity elicited the efflux of 3H-taurine with a threshold at –5 mOsm and D-[3H]aspartate (as marker for glutamate) and at –20 mOsm for [3H]GABA. The efflux rate of [3H]taurine was always notably higher than those of [3H]GABA and D-[3H]aspartate, with a maximal increase over the isosmotic efflux of about 7-fold for [3H]taurine and 3- and 2-fold for [3H]GABA and D-[3H]aspartate, respectively. The amino acid content in slices exposed to 50% hyposmotic solutions (abrupt change) during 20 min decreased by 50.6% and 62.6% (gradual change). Taurine and glutamate showed the largest decrease. An enhancement in 86Rb efflux and a corresponding decrease in K+ tissue content was seen in association with RVD but not with IVR. These results demonstrate the contribution of amino acids to IVR and indicate their involvement in this mechanism of cell volume control

Efflux of Osmolyte Amino Acids during Isovolumic Regulation in Hippocampal Slices

The efflux of potassium (K+) and amino acids from hippocampal slices was measured after sudden exposure to 10% (270 mOsm), 25% (225 mOsm) or 50% (150 mOsm) hyposmotic solutions or after gradual decrease (22.5 mOsm/min) in external osmolarity. In slices suddenly exposed to 50% hyposmotic solutions, swelling was followed by partial (74%) cell volume recovery, suggesting regulatory volume decrease (RVD). With gradual hyposmotic changes, no increase in cell water content was observed even when the solution at the end of the experiment was 50% hyposmotic, showing the occurrence of isovolumic regulation (IVR). The gradual decrease in osmolarity elicited the efflux of 3H-taurine with a threshold at –5 mOsm and D-[3H]aspartate (as marker for glutamate) and at –20 mOsm for [3H]GABA. The efflux rate of [3H]taurine was always notably higher than those of [3H]GABA and D-[3H]aspartate, with a maximal increase over the isosmotic efflux of about 7-fold for [3H]taurine and 3- and 2-fold for [3H]GABA and D-[3H]aspartate, respectively. The amino acid content in slices exposed to 50% hyposmotic solutions (abrupt change) during 20 min decreased by 50.6% and 62.6% (gradual change). Taurine and glutamate showed the largest decrease. An enhancement in 86Rb efflux and a corresponding decrease in K+ tissue content was seen in association with RVD but not with IVR. These results demonstrate the contribution of amino acids to IVR and indicate their involvement in this mechanism of cell volume control

Óscar Wilde (1854-1900): del arte por el arte a una cena con panteras.

En este artículo se intenta hacer un balance de la herencia política, humanística y estética del brillante escritor irlandés Óscar Wilde (1854-1900). El año pasado (2000) se recordaron cien años de su muerte y con este artículo el autor quiso contribuir a rescatar esa herencia invaluable de tolerancia, espíritu de sacrificio y solidaridad que se expresan en toda la obra de Wilde. Dramaturgo, ensayista, poeta, narrador y crítico, Óscar Wilde es un ejemplo de hasta donde puede llegar un hombre, un intelectual, para defender, incluso bajo amenaza de cárcel y muerte, su derecho a la libertad y a tener vida privada

Influence of track modelling in modal parameters of railway bridges composed by single-track adjacent decks

[EN] A significant number of railway bridges composed by simply-supported (SS) spans are present in existing railway lines. Special attention must be paid to short to medium span length structures, as they are prone to experience high vertical acceleration levels at the deck, due to their low weight and damping, compromising the travelling comfort and the structural integrity. The accurate prediction of the dynamic response of these bridges is a complex issue since it is affected by uncertain factors such as structural damping and complex interaction mechanisms such as vehicle-bridge, soil-structure or track-bridge interaction. Concerning track-bridge interaction, experimental evidences of a dynamic coupling exerted by the ballasted track between subsequent SS spans and also between structurally independent single-track twin adjacent decks have been reported in the literature [1, 2]. Nevertheless, this phenomenon is frequently disregarded due to the computational cost of models including the track and due to the uncertainties in the mechanical parameters that define the track system. The present work contributes to the study of the coupling effect exerted by the ballasted track between independent structures in railway bridges. With this purpose two 3D finite element (FE) track-bridge interaction models are implemented. The former includes a continuous representation of the track components meshing the sleepers, ballast and sub-ballast with solid FE. In the latter, the track is represented as a 2D discrete three-layer model where the mass, stiffness and damping of the components are concentrated at the sleepers locations. The numerical models are updated with experimental measurements performed on an existing railway bridge in a view to evaluate (i) the influence of the track continuity on the bridge modal parameters and on the train-induced vibrations; (ii) the adequacy of the implemented numerical models and (iii) the importance of the track-bridge interaction for an accurate prediction of the vertical acceleration levels under operating conditions.The authors would like to acknowledge the financial support provided by the Spanish Ministry of Science and Innovation under research project PID2019-109622RB; FEDER Andalucía 2014-2020 Operational Program for project US-126491; Generalitat Valenciana and Universitat Jaume I under research projects AICO2019/175 and UJI/A2008/06; and the Andalusian Scientific Computing Centre (CICA).Sánchez Quesada, J.; Moliner, E.; Romero, A.; Galvín, P.; Martínez-Rodrigo, M. (2022). Influence of track modelling in modal parameters of railway bridges composed by single-track adjacent decks. En Proceedings of the YIC 2021 - VI ECCOMAS Young Investigators Conference. Editorial Universitat Politècnica de València. 278-287. https://doi.org/10.4995/YIC2021.2021.12283OCS27828

Spectral properties of muscle activation during incremental cycling test

It is uncertain whether fatigue and workload would affect muscle recruitment during cycling. To infer on changes in priority for recruitment of motor units, we assessed the combined effects of fatigue and workload during an incremental cycling test to exhaustion on frequency components of lower limbs muscle activation. Competitive cyclists performed an incremental maximal cycling test while muscle activations were recorded from the right and left vastus lateralis, biceps femoris and gastrocnemius medialis. Muscle activation signals were assessed using frequency band analyses and decomposed into overall, high and low frequency bands. Combined effects from workload/fatigue were assessed using t tests and Cohen¿s effect sizes (ES). There were increases in the overall muscle activation due to increased workload/fatigue for biceps femoris (40% vs. 90%, p<0.01 and ES = 1.85) and vastus lateralis (40% vs. 70%, p=0.01 and ES = 0.96, and 40% vs. 90%, p<0.01 and ES = 2.03, and 70% vs. 90%, p<0.01 and ES = 0.96), but not for gastrocnemius medialis. There was also greater contribution from low frequency component for biceps femoris (40% vs. 90%, p = 0.01 and ES = 1.12). Similar workload/fatigue effects have been observed between lower limbs. In conclusion, incremental cycling test lead to an increase in activation of main knee joint flexors and extensors but not in plantar flexors during cycling. Biceps femoris changes its recruitment profile due to increases in low frequency content

Un método numérico híbrido para capturar los choques en leyes de conservación escalares

En este trabajo se estudia numéricamente la aproximación del problema de Cauchy para una ley de conservación escalar, utilizando una técnica mixta que combina los principios de volúmenes finitos y de conjuntos de nivel para capturar con alto orden la solución entrópica a lo largo de las discontinuidades. La ley de conservación se aproxima por un esquema de volúmenes finitos de segundo orden que evita el incremento de la difusión numérica en las discontinuidades incorporando estados fantasmas a ambos lados de las curvas de choque, las cuales son consideradas como una curva implícita que es calculada mediante el método de conjuntos de nivel. Se presentan ejemplos numéricos de aplicación del método híbrido y que ilustran la buenas propiedades de aproximación de este método en los sectores en los cuales existen discontinuidades.

An hybrid numerical method to shock capturing in scalar conservation laws

In this paper we study numerically the approximation of the Cauchy problem for a scalar conservation law by using a mixed technique which combines the principles of finite volume and level sets methods to capture with high-order the entropy solution along discontinuities. The conservation law is approximated by a finite volume scheme of second order that prevents the increase of numerical diffusion on discontinuities by incorporating ghosts states on both sides of the shock curves, which are considered as a implicit curve that is computed via the method of level sets. We present some numerical examples with application of the hybrid method and illustrate the high order accuracy belong to shock curves.En este trabajo se estudia numéricamente la aproximación del problema de Cauchy para una ley de conservación escalar, utilizando una técnica mixta que combina los principios de volúmenes finitos y de conjuntos de nivel para capturar con alto orden la solución entrópica a lo largo de las discontinuidades. La ley de conservación se aproxima por un esquema de volúmenes finitos de segundo orden que evita el incremento de la difusión numérica en las discontinuidades incorporando estados fantasmas a ambos lados de las curvas de choque, las cuales son consideradas como una curva implícita que es calculada mediante el método de conjuntos de nivel. Se presentan ejemplos numéricos de aplicación del método híbrido y que ilustran la buenas propiedades de aproximación de este método en los sectores en los cuales existen discontinuidades. &nbsp

An hybrid numerical method to shock capturing in scalar conservation laws

In this paper we study numerically the approximation of the Cauchy problem for a scalar conservation law by using a mixed technique which combines the principles of finite volume and level sets methods to capture with high-order the entropy solution along discontinuities. The conservation law is approximated by a finite volume scheme of second order that prevents the increase of numerical diffusion on discontinuities by incorporating ghosts states on both sides of the shock curves, which are considered as a implicit curve that is computed via the method of level sets. We present some numerical examples with application of the hybrid method and illustrate the high order accuracy belong to shock curves.En este trabajo se estudia numéricamente la aproximación del problema de Cauchy para una ley de conservación escalar, utilizando una técnica mixta que combina los principios de volúmenes finitos y de conjuntos de nivel para capturar con alto orden la solución entrópica a lo largo de las discontinuidades. La ley de conservación se aproxima por un esquema de volúmenes finitos de segundo orden que evita el incremento de la difusión numérica en las discontinuidades incorporando estados fantasmas a ambos lados de las curvas de choque, las cuales son consideradas como una curva implícita que es calculada mediante el método de conjuntos de nivel. Se presentan ejemplos numéricos de aplicación del método híbrido y que ilustran la buenas propiedades de aproximación de este método en los sectores en los cuales existen discontinuidades. &nbsp

Structure and Expression of Bud Dormancy-Associated MADS-Box Genes (DAM) in European Plum

Bud dormancy in temperate perennials ensures the survival of growing meristems under the harsh environmental conditions of autumn and winter, and facilitates an optimal growth and development resumption in the spring. Although the molecular pathways controlling the dormancy process are still unclear, DORMANCY-ASSOCIATED MADS-BOX genes (DAM) have emerged as key regulators of the dormancy cycle in different species. In the present study, we have characterized the orthologs of DAM genes in European plum (Prunus domestica L.). Their expression patterns together with sequence similarities are consistent with a role of PdoDAMs in dormancy maintenance mechanisms in European plum. Furthermore, other genes related to dormancy, flowering, and stress response have been identified in order to obtain a molecular framework of these three different processes taking place within the dormant flower bud in this species. This research provides a set of candidate genes to be genetically modified in future research, in order to better understand dormancy regulation in perennial species