Análisis de la sensibilidad del ensayo de resonancia por impacto como herramienta para determinar las propiedades elásticas de materiales bituminosos

The modulus value of bituminous materials is a key factor in the design of road pavements and the estimation of their life service. This parameter can be measured in laboratory but, unfortunately, this requires the deterioration of the pavement so as the consumption of time and resources. Therefore, this study analyses the feasibility of using impact resonance frequency tests as an alternative to traditional methods for determining the dynamic modulus of bituminous mixtures. The sensitivity of this technique has been studied by analyzing its repeatability and reproducibility, studying the variations in the values measured by modifying the dimensions of the specimens, test temperatures and types of mixture tested. In addition, this non-destructive technique has been compared with other traditional tests used to determine the elastic properties of bituminous materials. The results show that this test could be an interesting tool to characterize the properties and damage state of asphalt layers.El valor de módulo de los materiales bituminosos es un factor clave en el diseño de pavimentos y la estimación de su vida de servicio. Este parámetro puede ser medido en laboratorio pero, desafortunadamente, esto requiere deteriorar el pavimento así como el consumo de tiempo y recursos. Por ello, este estudio analiza la viabilidad de usar el ensayo de frecuencia de resonancia mediante impacto como alternativa a los métodos tradicionales para determinar el módulo dinámico de mezclas bituminosas. La sensibilidad de esta técnica se ha estudiado analizando su repetibilidad y reproducibilidad, estudiando variaciones en los valores medidos al modificar dimensiones de probetas, temperaturas y tipos de mezcla ensayados. Además, esta técnica no destructiva se ha comparado con otros ensayos tradicionales empleados para determinar propiedades elásticas de materiales bituminosos. Los resultados muestran este ensayo como una herramienta interesante para caracterizar las propiedades y estado de daño de las capas de asfalto

Identification of electroactive sites in Prussian Yellow films

Prussian Blue films were electrogenerated on the surface of the transparent ITO electrodes. The electrochemical oxidation to the Prussian Yellow form was investigated by means of in situ voltammetry and vis–NIR spectroscopic techniques. Changes of the whole spectra between 400 and 950 nm were analyzed and three characteristic wavelengths were selected to in situ follow the electrochemical changes of the films. Voltammetric peaks and absorbance derivative curves at these three wavelengths were deconvoluted and were interpreted such as the overlapping of different electrochemical processes. The correlation between these overlapped processes has allowed proposing three different electrochemical processes for the interpretation of the whole electrochemical response. One of these processes corresponds to the oxidation of View the MathML source units where the electrical charge is balanced by the exchange of neighbor potassium cations. The second one is associated to the oxidation of View the MathML source trapped sites and the third one also to the oxidation of View the MathML source units but in this last case, the absence of neighbor potassium cations causes that the electrical charge balance takes place by the exchange of some anions such as the chloride. These processes have been identified on the basis of previous results and on the interesting information provided by the coupling voltammetry and absorbance derivative curves at these characteristic wavelengths

Diachronic analiysis of motor comunication in traditional games and sports of the canary island

Se realiza un análisis diacrónico de la comunicación motriz en tres grupos de juegos y deportes tradicionales canarios ('juegos aborígenes', 'juegos tradicionales', y 'deportes tradicionales') para deducir pautas sociales que encierran estas prácticas. Se analizan y categorizan la red de comunicación motriz y la interacción motriz siguiendo criterios de la praxiología motriz. Bajo el significado del enfrentamiento como función lúdica principal, la estructura dualista se muestra de manera hegemónica, en detrimento de otras formas de comunicación motriz. También, se desvela que la diversificación de la interacción motriz del grupo 'juegos tradicionales' no es equivalente en los otros grupos estudiados, mostrando aquel grupo significados etnomotores hetereogéneos para una misma actividad. Las prácticas motrices estudiadas dan idea de la complejidad de la construcción de la tradición lúdica canariaA diachronic analysis of motor communication in three groups of traditional Canary Island games (‘aboriginal games’, ‘traditional games’, and ‘traditional sports’) was carried out in order to detect and define their social models. Both motor communication and motor interaction were analyzed and categorized according to motor praxeology criteria. When confrontation was the main function of the game, the dual structure was dominant over other forms of motor communication. The motor interaction diversification in the ‘traditional games’ group was not comparable to the other two groups due to the various ethno-motor modes used for the same activity. The motor study allows us to form an idea of the complexity of the construct of traditional Canary game

Treatment of recurrent aphtous stomatitis: A systematic review

Background: Recurrent Aphtous Stomatitis (RAS) is the most common process affecting the oral mucosa. It is painful, multifactorial and generally recurrent. The aim of this systematic review is to know the last treatment approaches and their effectivity.Material and Methods: we compared the outcome of different kind of treatments in terms of the improvement of the lesions, reduction of the size of those lesions and the time needed for their healing. Inclusion criteria were: clinical trials, articles written in English or Spanish and published less than 5 years ago.Results: we used the following keywords: treatment, aphtous stomatitis, canker sores; combined with Bool-ean operators AND y OR. We selected 28 articles for reading the whole text, and after applying the eligibility criteria, we selected 17 articles for our revision. Among all the treatments, we emphasize the barrier method based in compound of cellulose rubber and a calcium/sodium copolymer PVM/MA, with which the difference in the 3rd and 7th day was of-6,29 +/- 0,14 points in the pain score. The treatment with insulin and chitosan gel, brought a pain suppression on the third day, with no reactivation of the pain during the whole study. The application of a film composed of polyurethane and sesame oil with chitosan, brought a reduction in the size of the lesions of 4,54 +/- 2,84mm on the 6th day compared with the situation before the beginning of the treatment. The different kinds of laser, which produced a reduction in the pain score just at the beginning of the treatment up to 8,1 +/- 1,6 points, and a reduction of the size of the lesions of 4,42 +/- 1,02mm on the 7th day.Conclusions: Besides the classic treatments for RAS, we have to take into account other treatment modalities, above all the different kinds of laser

Evaluación del comportamiento mecánico de capas bituminosas ultra delgadas como una adecuada estrategia para la rehabilitación de pavimentos urbanos

Very Thin Asphalt Overlay (VTAO) has been introduced as an alternative to traditional thick overlays, seal coats, and micro-surfacings. Nonetheless, there are some challenges that still remain regarding the application of VTAOs (such as mixture type, cohesiveness, wear resistance, cracking and durability), particularly in heavy traffic urban areas. Therefore, this paper presents an extensive comparative evaluation of the mechanical performance, durability and safety issues (cohesiveness, adhesiveness, ageing, cracking, plastic deformation, permeability, macrotexture, skid and wear resistance, and fuel resistance) of a VTAO (20 mm thick) and a high performance BBTM 11B (35 mm thick), commonly used as an open-graded mixture for pavement overlays. The results demonstrated that VTAO is an appropriate material for urban pavements as it provides good durability and resistance to the propagation of defects. Nonetheless, further studies are required to improve its behavior under distresses related to plastic deformations and safety properties.Las capas bituminosas ultra delgadas para rehabilitación superficial de carreteras son una alternativa a las tradicionales capas asfálticas, riegos bituminosos y micro-aglomerados. No obstante, aún son numerosos los aspectos a estudiar para la generalización de su uso, particularmente en zonas urbanas con elevado tráfico. Así, este artículo recoge un análisis comparativo del comportamiento mecánico, durabilidad y factores de seguridad (evaluando parámetros como cohesividad, adhevisvidad, envejecimiento, fisuración, deformaciones, permeabilidad, macrotextura, y resistencia al deslizamiento, al desgaste y a los combustibles) entre una capa delgada de 20 mm de espesor, y una mezcla discontinua de altas prestaciones (BBTM-11B con 35 mm), comúnmente utilizada en capas de rodadura. Los resultados indican que puede ser una adecuada solución para pavimentos urbanos dada su durabilidad y resistencia a la propagación de fallos. No obstante, se requieren futuros estudios centrados en la mejora de parámetros de seguridad y de su resistencia a las deformaciones permanentes

Affine convex body semigroups

In this paper we present a new kind of semigroups called convex body semigroups which are generated by convex bodies of R^k. They generalize to arbitrary dimension the concept of proportionally modular numerical semigroup of [7]. Several properties of these semigroups are proven. Affine convex body semigroups obtained from circles and polygons of R^2 are characterized. The algorithms for computing minimal system of generators of these semigroups are given. We provide the implementation of some of them

Comparación entre las historias completas y truncadas de nacimientos para medir la fecundidad y la mortalidad de la niñez

Incluye BibliografíaComparación entre las técnicas de recopilación de datos de fecundidad a través de historias truncadas y de historias completas de nacimientos, en la experiencia en Perú, 1986