1,980 research outputs found

    GRAMPAL: A Morphological Processor for Spanish implemented in Prolog

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    A model for the full treatment of Spanish inflection for verbs, nouns and adjectives is presented. This model is based on feature unification and it relies upon a lexicon of allomorphs both for stems and morphemes. Word forms are built by the concatenation of allomorphs by means of special contextual features. We make use of standard Definite Clause Grammars (DCG) included in most Prolog implementations, instead of the typical finite-state approach. This allows us to take advantage of the declarativity and bidirectionality of Logic Programming for NLP. The most salient feature of this approach is simplicity: A really straightforward rule and lexical components. We have developed a very simple model for complex phenomena. Declarativity, bidirectionality, consistency and completeness of the model are discussed: all and only correct word forms are analysed or generated, even alternative ones and gaps in paradigms are preserved. A Prolog implementation has been developed for both analysis and generation of Spanish word forms. It consists of only six DCG rules, because our {\em lexicalist\/} approach --i.e. most information is in the dictionary. Although it is quite efficient, the current implementation could be improved for analysis by using the non logical features of Prolog, especially in word segmentation and dictionary access.Comment: 11 page

    A framework for lexical representation

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    In this paper we present a unification-based lexical platform designed for highly inflected languages (like Roman ones). A formalism is proposed for encoding a lemma-based lexical source, well suited for linguistic generalizations. From this source, we automatically generate an allomorph indexed dictionary, adequate for efficient processing. A set of software tools have been implemented around this formalism: access libraries, morphological processors, etc.Comment: 9 page

    Study of alkaline hydrothermal activation of belite cements by thermal analysis

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    The effect of alkaline hydrothermal activation of class-C fly ash belite cement was studied using thermal analysis (TG/DTG) by determining the increase in the combined water during a period of hydration of 180 days. The results were compared with those obtained for a belite cement hydrothermally activated in water. The two belite cements were fabricated via the hydrothermal-calcination route of class-C fly ash in 1 M NaOH solution (FABC-2-N) or demineralised water (FABC-2-W). From the results, the effect of the alkaline hydrothermal activation of belite cement (FABC-2-N) was clearly differentiated, mainly at early ages of hydration, for which the increase in the combined water was markedly higher than that of the belite cement that was hydrothermally activated in water. Important direct quantitative correlations were obtained among physicochemical parameters, such as the combined water, the BET surface area, the volume of nano-pores, and macro structural engineering properties such as the compressive mechanical strength

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    Formulación de cementos bioactivos mediante la adición de sales de Hidroxiapatita-Estroncio

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    Se han formulado cementos óseos acrílicos inyectables para su uso en vertebroplastia (VP) y se les ha proporcionado bioactividad mediante la incorporación de sales de hidroxiapatita estroncio (HASr). El objetivo es combinar la fijación inmediata que proporciona el cemento acrílico, con la fijación a largo plazo que proporciona la HASr. Además, la presencia de Sr en la carga proporciona radiopacidad, con lo cual se evita la adición de agentes radiopacos adicionales. Así, se estudió el efecto de la incorporación de la HASr en las propiedades del cemento óseo. La adición se realizó en la fase sólida de 2 modos diferentes: en polvo, tal como se obtiene tras la síntesis y después de un sencillo tratamiento superficial con monómero. Los resultados muestran que el tratamiento mejora la mojabilidad de las partículas, lo que mejora la inyección de estos cementos y proporciona propiedades mecánicas superiores, sin perjudicar al contenido de monómero residual. La formulación de cemento idónea para VP sería la que contiene un 20% de HASr tratada, ya que presenta una inyectabilidad mejorada, elevada radiopacidad, la mayor bioactividad y además, la mejora de propiedades mecánicas es significativa

    Formulación de cementos bioactivos mediante la adición de sales de hidroxiapatita-estroncio

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    Se han formulado cementos óseos acrílicos inyectables para su uso en vertebroplastia (VP) y se les ha proporcionado bioactividad mediante la incorporación de sales de hidroxiapatita estroncio (HASr). El objetivo es combinar la fijación inmediata que proporciona el cemento acrílico, con la fijación a largo plazo que proporciona la HASr. Además, la presencia de Sr en la carga proporciona radiopacidad, con lo cual se evita la adición de agentes radiopacos adicionales. Así, se estudió el efecto de la incorporación de la HASr en las propiedades del cemento óseo. La adición se realizó en la fase sólida de 2 modos diferentes: en polvo, tal como se obtiene tras la síntesis y después de un sencillo tratamiento superficial con monómero. Los resultados muestran que el tratamiento mejora la mojabilidad de las partículas, lo que mejora el mezclado de estos cementos y proporciona propiedades mecánicas superiores. La formulación de cemento idónea para VP sería la que contiene un 20% de HASr tratada, ya que presenta una elevada radiopacidad, la mayor bioactividad y además, la mejora de propiedades mecánicas es significativa.Bioactive and injectable bone cements designed to perform vertebroplasty (VP) have been prepared by adding strontium hydroxyapatite (SrHA) to a formulation based on methylmethacrylate. Thus, the cement combines the immediate support given by the setting of the acrylic matrix, with the long term integration due to the incorporation of the SrHA. Moreover, the presence of Strontium makes this filler highly radiopaque, which avoids the undesirable and extended practice of the addition of more radiopaque substances by the surgeon. For that purpose, the effect of the addition of SrHA particles, incorporated ‘as synthetised’ and after a surface treatment with the monomer, was studied on various properties of the cement. Results showed that the surface treatment improved the wettability of the SrHA particles, and, as a consequence, the mixing and the mechanical properties. The best formulation to perform VP is 20%-treated SrHA containing formulation, which shows enhanced mechanical properties compared with control formulations, along with high radiopacity and the higher bioactivity

    Early stages of LDL oxidation: apolipoprotein B structural changes monitored by infrared spectroscopy.

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    Changes in the conformation of apoliprotein B-100 in the early stages of copper-mediated low density lipoprotein oxidation have been monitored by infrared spectroscopy. During the lag phase no variation in structure is observed, indicating that copper binding to the protein does not significantly affect its structure. In the propagation phase, while hydroperoxides are formed but the protein is not modified, no changes in secondary structure are observed, but the thermal profile of the band corresponding to alpha-helix is displaced in frequency, indicating changes in tertiary structure associated with this conformation but not with beta-sheet components. When aldehyde formation starts, a decrease of approximately 3% in the area of bands corresponding to alpha-helix and beta-sheet is produced, concomitantly with an increase in beta-turns and unordered structure. The two bands corresponding to beta-turns vary as well under these conditions, indicating changes in these structures. Also at this stage the thermal profile shows variations in frequency for the bands corresponding to both alpha-helix and beta-sheet.The results are consistent with the hypothesis that as soon as the polyunsaturated fatty acids from the particle core are modified, this change is reflected at the surface, in the alpha-helical components contacting the monolayer.Fil: Chehin, Rosana Nieves. Consejo Superior de Investigaciones Científicas; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Universidad del País Vasco; EspañaFil: Rengel, David. Consejo Superior de Investigaciones Científicas; España. Universidad del País Vasco; EspañaFil: Milicua, José Carlos G.. Universidad del País Vasco; España. Consejo Superior de Investigaciones Científicas; EspañaFil: Goñi, Félix M.. Universidad del País Vasco; España. Consejo Superior de Investigaciones Científicas; EspañaFil: Arrondo JL. Consejo Superior de Investigaciones Científicas; España. Universidad del País Vasco; EspañaFil: Pifat, Greta. Rudjer Bošković Institute; Croaci
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