166 research outputs found

    Mineralogía y ceramicidad de las arcillas del yacimiento de Sitjar, Onda (Castellón)

    Get PDF
    Este trabajo tiene por objeto la caracterización mineralógica y físico-química de las arcillas terciarias explotadas en el yacimiento de Sitjar, cercano a la localidad de Onda (Castellón), utilizadas comomateria prima por la industria ceramica castellonense. Se estudian también algunas propiedades ceramicas de estas arcillas, incidiendo en el comportamiento térmico, para su correcta aplicación. a composición química y mineralógica posibilita su utilización como aditivo para la fabricaci6n de materiales porosos y refractarios

    Resistencia mecánica y porosidad de soportes para pavimentos y revestimientos cerámicos obtenidos con arcillas de Castellón

    Get PDF
    We have tried to establish a relationship between the raw material and the mechanical properties of ceramic pieces subjected to different firing processes, so under the determinant of the thermal process we have done a follow up on the petrogenetic process that the manufacture of ceramics represents. This is evaluated in terms of the mechanical behaviour of the ceramic tile bodies, which have been normalised and submitted to tests for flexion. The principal objective is to be able to indicate what the optimum firing temperature for each sample is, and to determine what it is in the ceramic body which offers the greatest resistance when a specific force is applied. The study of the texture of the ceramic body will be considered mainly in relation to the existent porosity, as well as its distribution, which conditions its characteristics and specifications. The relation between porosity and the parameters that describe the porous texture of the ceramic tile pieces studied is complicated because of the fact that these have many pores with a complex and irregular spatial disposition, with a broad distribution of forms and sizes, and as such they do not fit into established empirical equations.Se ha tratado de establecer la relación entre materia prima y propiedades mecánicas de piezas cerámicas sometidas a procesos de cocción diversos. Bajo el condicionante del proceso térmico se realiza un seguimiento del proceso petrogenético que representa la fabricación cerámica y se evalúa a través del comportamiento mecánico de probetas cerámicas normalizadas y sometidas a ensayos de flexión. El objetivo principal es poder indicar cuál es la temperatura óptima de cocción para cada muestra y determinar cuál es aquélla en que la probeta cerámica ofrece una mayor resistencia al aplicarle una determinada carga. El estudio de la textura de la matriz cerámica es de gran interés en relación con la porosidad, asi como su distribución, que condiciona sus características y aplicaciones. La relación existente entre la porosidad y los parámetros relacionados con la textura porosa es muy compleja debido a la distribución irregular de formas y tamaños de poro, que no se ajusta a ninguna ecuación empírica establecida, pero aun así hay aproximaciones teóricas que pueden permitir prevenir la relación entre la porosidad y las propiedades mecánicas

    Graph edit distance or graph edit pseudo-distance?

    Get PDF
    Graph Edit Distance has been intensively used since its appearance in 1983. This distance is very appropriate if we want to compare a pair of attributed graphs from any domain and obtain not only a distance, but also the best correspondence between nodes of the involved graphs. In this paper, we want to analyse if the Graph Edit Distance can be really considered a distance or a pseudo-distance, since some restrictions of the distance function are not fulfilled. Distinguishing between both cases is important because the use of a distance is a restriction in some methods to return exact instead of approximate results. This occurs, for instance, in some graph retrieval techniques. Experimental validation shows that in most of the cases, it is not appropriate to denominate the Graph Edit Distance as a distance, but a pseudo-distance instead, since the triangle inequality is not fulfilled. Therefore, in these cases, the graph retrieval techniques not always return the optimal graph

    Graph similarity through entropic manifold alignment

    Get PDF
    In this paper we decouple the problem of measuring graph similarity into two sequential steps. The first step is the linearization of the quadratic assignment problem (QAP) in a low-dimensional space, given by the embedding trick. The second step is the evaluation of an information-theoretic distributional measure, which relies on deformable manifold alignment. The proposed measure is a normalized conditional entropy, which induces a positive definite kernel when symmetrized. We use bypass entropy estimation methods to compute an approximation of the normalized conditional entropy. Our approach, which is purely topological (i.e., it does not rely on node or edge attributes although it can potentially accommodate them as additional sources of information) is competitive with state-of-the-art graph matching algorithms as sources of correspondence-based graph similarity, but its complexity is linear instead of cubic (although the complexity of the similarity measure is quadratic). We also determine that the best embedding strategy for graph similarity is provided by commute time embedding, and we conjecture that this is related to its inversibility property, since the inverse of the embeddings obtained using our method can be used as a generative sampler of graph structure.The work of the first and third authors was supported by the projects TIN2012-32839 and TIN2015-69077-P of the Spanish Government. The work of the second author was supported by a Royal Society Wolfson Research Merit Award

    MicroRNA-335-5p suppresses voltage-gated sodium channel expression and may be a target for seizure control

    Get PDF
    There remains an urgent need for new therapies for treatment-resistant epilepsy. Sodium channel blockers are effective for seizure control in common forms of epilepsy, but loss of sodium channel function underlies some genetic forms of epilepsy. Approaches that provide bidirectional control of sodium channel expression are needed. MicroRNAs (miRNA) are small noncoding RNAs which negatively regulate gene expression. Here we show that genome-wide miRNA screening of hippocampal tissue from a rat epilepsy model, mice treated with the antiseizure medicine cannabidiol, and plasma from patients with treatment-resistant epilepsy, converge on a single target-miR-335-5p. Pathway analysis on predicted and validated miR-335-5p targets identified multiple voltage-gated sodium channels (VGSCs). Intracerebroventricular injection of antisense oligonucleotides against miR-335-5p resulted in upregulation of Scn1a, Scn2a, and Scn3a in the mouse brain and an increased action potential rising phase and greater excitability of hippocampal pyramidal neurons in brain slice recordings, consistent with VGSCs as functional targets of miR-335-5p. Blocking miR-335-5p also increased voltage-gated sodium currents and SCN1A, SCN2A, and SCN3A expression in human induced pluripotent stem cell-derived neurons. Inhibition of miR-335-5p increased susceptibility to tonic-clonic seizures in the pentylenetetrazol seizure model, whereas adeno-associated virus 9-mediated overexpression of miR-335-5p reduced seizure severity and improved survival. These studies suggest modulation of miR-335-5p may be a means to regulate VGSCs and affect neuronal excitability and seizures. Changes to miR-335-5p may reflect compensatory mechanisms to control excitability and could provide biomarker or therapeutic strategies for different types of treatment-resistant epilepsy
    corecore