632 research outputs found

    Conservation status and updated census of Patella ferruginea (Gastropoda, Patellidae) in Ceuta: distribution patterns and new evidence of the effects of environmental parameters on population structure

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    The Strait of Gibraltar has important populations of the highly endangered patellid limpet Patella ferruginea. Between 2006 and 2010, an exhaustive census was carried out in Ceuta. The total coastline was divided into 17 sectors. The coast of each sector was examined by using 10 m transects. For the case of those sectors composed of breakwaters, jetties or islets, no transects were used, and instead, the total number of individuals was recorded. Each individual was measured to the nearest millimetre using a calliper. Moreover, the complete rocky shore length where the species could potentially be present was calculated, and an estimation of the total number of individuals that each sector could host was made. Results indicate that Ceuta could be home to around 44,000 individuals. The species found in Point Benzú, its westernmost limit of distribution on the North African coasts. The largest populations were recorded on the South Bay, with higher Mediterranean influence. Our results indicate that substrate roughness (topographic heterogeneity) and the area’s accessibility highly influence the abundance and population structure. Those populations located on high topographic heterogeneity substrates show higher recruitment rates and lower percentages of larger individuals, while medium to low rugosity surfaces presented the opposite pattern. Additionally, easily accessible areas (and frequented by humans) presented smaller average shell sizes. Implications of the results for conservation purposes are discussed

    Ultrasonic, Molecular and Mechanical Testing Diagnostics in Natural Fibre Reinforced, Polymer-Stabilized Earth Blocks

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    The aim of this research study was to evaluate the influence of utilising natural polymers as a form of soil stabilization, in order to assess their potential for use in building applications. Mixtures were stabilized with a natural polymer (alginate) and reinforced with wool fibres in order to improve the overall compressive and flexural strength of a series of composite materials. Ultrasonic pulse velocity (UPV) and mechanical strength testing techniques were then used to measure the porous properties of the manufactured natural polymer-soil composites, which were formed into earth blocks. Mechanical tests were carried out for three different clays which showed that the polymer increased the mechanical resistance of the samples to varying degrees, depending on the plasticity index of each soil. Variation in soil grain size distributions and Atterberg limits were assessed and chemical compositions were studied and compared. X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), and energy dispersive X-ray fluorescence (EDXRF) techniques were all used in conjunction with qualitative identification of the aggregates. Ultrasonic wave propagation was found to be a useful technique for assisting in the determination of soil shrinkage characteristics and fibre-soil adherence capacity and UPV results correlated well with the measured mechanical properties

    Optimización de propiedades mecánicas y térmicas de un aglomerado sintético por el Método de Taguchi

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    In this work, the Taguchi Experimental Design model was applied for the optimization of the mechanical and thermal properties of an agglomerated composite material and to obtain the most appropriate parameters for its elaboration. The importance of the development of synthetic agglomerates is in the use of agricultural waste to give it a useful use when supplying high demand materials. Rice husk, clay, sand and aloe gel were used as raw materials. With the variation of the values ​​of the control factors: percentage of rice husk (R), temperature (T) and time of heat treatment (t), the different experimental combinations were performed. For the optimization of the mechanical and thermal properties according to the Taguchi methodology, the mechanical and thermal tests were selected: the modulus of elasticity, the energy absorbed in the impact, the modulus of maximum breakage and the initial decomposition temperature for each combination chipboard experimental. For the processing of this data, the software for the automatic design and analysis of Taguchi experiments, Qualitek-4, was used under the characteristic of higher-better quality. The optimal parameters obtained for each level of control were R = 15%, T = 120 C and t = 3 h. These results were validated with the performance of a confirmatory experiment, where properties similar to those of wood species were obtained for this agglomerate. The development of this prototype of alternative material will be useful as a substitute for wood and will contribute to the reduction of the environmental impact generated by waste products.En este trabajo se aplicó el modelo de Diseño Experimental de Taguchi para la optimización de las propiedades mecánicas y térmicas de un material compuesto aglomerado y obtener los parámetros más adecuados para su elaboración. La importancia del desarrollo de los aglomerados sintéticos está en el uso de desechos agrícolas para darle un empleo útil al suplir materiales de gran demanda. Se utilizaron la cáscara de arroz, arcilla, arena y gel de aloe como materias primas. Con la variación de los valores de los factores de control: porcentaje de cáscara de arroz (R), temperatura (T) y tiempo de tratamiento térmico (t), se realizaron las diferentes combinaciones experimentales. Para la optimización de las propiedades mecánicas y térmicas según la metodología de Taguchi, se seleccionaron de las pruebas mecánicas y térmicas: el módulo de elasticidad, la energía absorbida en el impacto, el módulo de rotura máximo y la temperatura inicial de descomposición para cada combinación experimental de aglomerado. Para el procesamiento de estos datos, se utilizó el software para el diseño automático y análisis de experimentos de Taguchi, Qualitek-4, bajo la característica de calidad mayor–mejor. Los parámetros óptimos obtenidos para cada nivel de control, fueron R = 15%, T = 120 C y t = 3 h. Estos resultados fueron validados con la realización de un experimento confirmatorio, donde se obtuvieron, para este aglomerado, propiedades similares a las de unas especies de madera. El desarrollo de este prototipo de material alternativo será útil como sustituyente de la madera y contribuirá a la reducción del impacto ambiental generado por los productos de desecho

    Optimización de propiedades mecánicas y térmicas de un aglomerado sintético por el Método de Taguchi

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    In this work, the experimental design of Taguchi model was applied in order to obtain the most appropriate parameters to elaborate an agglomerate material which presents a good mechanical and thermal behavior. The raw materials used were rice husk, common clay, sand and aloe gel. The importance of the development of the synthetic agglomerates is in the use of agricultural wastes to give them an useful employment when replacing materials of great demand. The experimental combinations were done varying the control factors values: rice husk percentage (R), temperature (T) and thermal treatment time(t). Via to the optimization properties according Taguchi’s Methodology, the elasticity modulus, the absorbed energy in the impact, break maximum module and initial decomposition temperature to each experimental combination were selected. The Qualitek-4 software was used below the biggest the better quality characteristic. The optimum parameters obtained to each control level were: R = 15%, T = 120oC and t = 3 h. These results were confirmed with a new experiment, where similar properties to the wood species were obtained. The developing of this will be useful as substitute of the wood and could improve the environment impact due residual materials.PACS: 88.30.mj, 81.70.Bt, 82.35.PqMSC: 91B82En este trabajo se aplicó el modelo de Diseño Experimental de Taguchi para la optimización de las propiedades mecánicas y térmicas de un material compuesto aglomerado y obtener los parámetros más adecuados para su elaboración. La importancia del desarrollo de los aglomerados sintéticos está en el uso de desechos agrícolas para darle un empleo útil al suplir materiales de gran demanda. Se utilizaron la cáscara de arroz, arcilla, arena y gel de aloe como materias primas. Con la variación de los valores de los factores de control: porcentaje de cáscara de arroz (R), temperatura (T) y tiempo de tratamiento térmico (t), se realizaron las diferentes combinaciones experimentales. Para la optimización de las propiedades mecánicas y térmicas según la metodología de Taguchi, se seleccionaron de las pruebas mecánicas y térmicas: el módulo de elasticidad, la energía absorbida en el impacto, el módulo de rotura máximo y la temperatura inicial de descomposición para cada combinación experimental de aglomerado. Para el procesamiento de estos datos, se utilizó el software para el diseño automático y análisis de experimentos de Taguchi, Qualitek-4, bajo la característica de calidad mayor–mejor. Los parámetros óptimos obtenidos para cada nivel de control, fueron R = 15%, T = 120 C y t = 3 h. Estos resultados fueron validados con la realización de un experimento confirmatorio, donde se obtuvieron, para este aglomerado, propiedades similares a las de unas especies de madera. El desarrollo de este prototipo de material alternativo será útil como sustituyente de la madera y contribuirá a la reducción del impacto ambiental generado por los productos de desecho.PACS: 88.30.mj, 81.70.Bt, 82.35.PqMSC: 91B8

    Efectos inmunológicos de la vitamina D en COVID-19

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    El síndrome respiratorio severo o grave causado por el nuevo coronavirus (SARS-CoV-2) es una enfermedad de gran auge en la actualidad, que se ha propagado vertiginosamente a lo largo de los 5 continentes, siendo Norteamérica y algunos países europeos como Italia, España y Francia los más afectados por esta pandemia. En la actualidad, no se cuenta con una estrategia de prevención o tratamiento que logre mitigar de forma contundente las cifras de infectados y muertos a nivel mundial; sin embargo, se están estudiando alternativas que podrían impactar de forma positiva en el curso de la enfermedad. El déficit de 25 hidroxivitamina D (25OH D) ha mostrado ser un factor independiente de mortalidad por todas las causas, principalmente en enfermedades cardiovasculares y cáncer. La suplementación de esta también se ha asociado a beneficios en la prevención de enfermedades respiratorias; para el caso de la COVID-19, los mecanismos por los cuales la vitamina D podría ser útil para el tratamiento y la prevención se resumen en la actividad sobre las barreras físicas y la inmunidad natural celular y adaptativa, que disminuye la probabilidad de tormenta de citocinas. Algunos estudios realizados concluyeron que el pico de la infección por SARS-CoV-2 se presentó durante el invierno, tiempo donde los niveles de 25OH D son más bajos; además, estos niveles subóptimos se han relacionado con aumento en la incidencia de complicaciones tales como falla cardíaca, sepsis y progresión a síndrome de dificultad respiratoria del adulto (SDRA) y, por consiguiente, con un aumento en las tasas de mortalidad, lo cual respalda el papel de la vitamina D en la modificación del curso natural de la enfermedad. Sin embargo, también se prendieron las alarmas, ya que se ha demostrado una prevalencia alta de hipovitaminosis D en Bogotá, Villavicencio, Neiva, Barranquilla y Medellín, que podría exponer a la población colombiana a resultados adversos. La evidencia indica que la suplementación con vitamina D modula y reduce el riesgo de infección por SARS-CoV-2, pero se precisan más estudios para corroborar los efectos benéficos en la población

    SEOM Clinical Guideline for the diagnosis and treatment of esophageal cancer (2016)

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    Esophageal cancer (EC) is an aggressive tumor that represents the 6th most common cause of cancer death worldwide. The estimated incidence in Spain is 2090 cases/year. Two main pathological subtypes exist, squamous cell carcinoma and adenocarcinoma. The main differences between them are localization and underlying factors which are the principal cause of the recent incidence changes observed in west countries. Staging techniques and treatment options which combine surgery, chemotherapy and radiotherapy, reflected the high complexity of the EC management. An undeniably multidisciplinary approach is, therefore, required. In this guide, we review the status of current diagnosis and treatment, define evidence and propose recommendations

    Descriptive analysis of histological types in women undergoing post mastectomy breast reconstruction

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    Background: Breast cancer is a pathological entity that widely compromises the life and quality of life of affected women; in addition to the great affectation to the current health services. Therefore, maintaining an accurate and complete cancer registry program is one of the most important factors in implementing national cancer control programs and evaluating the results of screening, diagnosis, and treatment. Among the current limitations in the studies, there is a gap in the study of the population undergoing breast reconstruction. Methods: A retrospective study was carried out at hospital general de México “Dr. Eduardo Licéaga” with the information from the clinical records of the period 2019-2020. Patients undergoing breast reconstruction after mastectomy with histological report were included. Through non-probabilistic sampling, a population of 138 women was formed. For data analysis, frequencies and percentages were calculated for the qualitative variables; while for the quantitative variables, mean and standard deviation were calculated. Results: 138 women who underwent breast reconstruction were included, the mean age was 49.9±10.85 years, the mean BMI was 26.80±4.62 kg/m2, the secondary educational level predominated (34.8%), radiotherapy was applied to 34.1%, reconstruction was late in 75.4%, the most frequent reconstruction technique was TRAM flap (44.2%), the histological type of invasive ductal carcinoma predominated (68.1%). Conclusions: In women undergoing post-mastectomy breast reconstruction, the histological type of invasive ductal carcinoma predominates.

    IFE Plant Technology Overview and contribution to HiPER proposal

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    HiPER is the European Project for Laser Fusion that has been able to join 26 institutions and signed under formal government agreement by 6 countries inside the ESFRI Program of the European Union (EU). The project is already extended by EU for two years more (until 2013) after its first preparatory phase from 2008. A large work has been developed in different areas to arrive to a design of repetitive operation of Laser Fusion Reactor, and decisions are envisioned in the next phase of Technology Development or Risk Reduction for Engineering or Power Plant facilities (or both). Chamber design has been very much completed for Engineering phase and starting of preliminary options for Reactor Power Plant have been established and review here

    Índices de anillos de crecimiento en dos coníferas del Centro de México

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    Se determinaron índices de anillo de crecimiento (IAC) en Abies religiosa (Kunth Schltdl. et Cham) (oyamel) y Pinus hartwegii (Lindl.) (pino) en un transecto sobre el Eje Neo-volcánico Transversal, en México. La toma de muestras de anillos se realizó en seis montañas que presenan condiciones climáticas, geología, edafología suelo y vegetación similares. Las montañas son: Nevado de Colima, Pico de Tancítaro, Nevado de Toluca, Cerro Tláloc, La Malinche y Pico de Orizaba. Se colectaron virutas de incremento de al menos 20 árboles longevos de cada especie en cada sitio; sin embargo, para fines de este estudio se seleccionaron los árboles más representativos quedando entre 6 y 17 árboles de cada especie en cada montaña (144 árboles en total). Los resultados mostraron tendencias diferentes entre especies y montañas. Sin embargo, estimando valores promedio de IAC para el transecto, se observa que en el año 1935 hubo una reducción de crecimiento para ambas especies. El Oyamel mostró mayor variación en los IAC. De las dos especies, sólo en Oyamel se observó relación significativa entre los índices de anillo y la precipitación
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