144 research outputs found

    Aprovechamiento de barros procedentes de central de áridos para la elaboración de piezas cerámicas porosas

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    Aggregates (gravel and sand) are, after water, the Earth’s second most used natural resource, representing about 50% of all consumed mineral resources. Aggregate production generates a large quantity of waste from the aggregate washing process. This waste is made up of suspended solids – sludge – which has a great environmental impact. It is deposited in huge troughs because of the impossibility of discharging it directly into rivers. Many plants have incorporated decanters and filter presses to separate the solid from the liquid fraction. This paper evaluates the possibility of exploiting the solid fraction (i.e. sludge) in the manufacture of fired clay bricks. The added value of these bricks is, on the one hand, the exploitation of sludge as a currently useless waste product, and on the other, the use of this sludge to enhance the physical and mechanical properties of conventional fired clay bricks.Los áridos son la segunda materia prima más consumida en la Tierra después del agua, representando alrededor del 50% de todos los recursos minerales consumidos. El proceso de elaboración de estos áridos genera una gran cantidad de residuos procedentes de su lavado. Se trata de partículas sólidas en suspensión – lodos – de gran impacto ambiental, que se depositan en grandes charcas ante la imposibilidad de verterlos directamente al rio. Muchas empresas han incorporado decantadores y filtros de prensa para separar la fracción solida de la líquida. El presente trabajo evalúa la posibilidad de utilizar la fracción sólida, es decir el barro, para la fabricación de piezas cerámicas. El valor añadido de estas piezas es por un lado el aprovechamiento del barro como producto residual, que en estos momentos es desechable, y por otro, conseguir que este barro mejore las propiedades físico-mecánicas de la cerámica convencional

    Studying monogenetic volcanoes with a Terrestrial Laser Scanner: Case study at Croscat volcano (Garrotxa Volcanic Field, Spain)

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    Erosional processes (natural or anthropogenic) may partly destroy the relatively small-sized volcanic edifices characteristic of monogenetic volcanic zones, leaving their internal structure well exposed. Nevertheless, the study of these outcrops may be extremely challenging due to restricted accessibility or safety issues. Digital representations of the outcrop surface have been lately used to overcome such difficulties. Data acquired with terrestrial laser scanning instruments using Light Detection and Ranging technology enables the construction of such digital outcrops. The obtained high-precision 3-D terrain models are of greater coverage and accuracy than conventional methods and, when taken at different times, allow description of geological processes in time and space. Despite its intrinsic advantages and the proven satisfactory results, this technique has been little applied in volcanology-related studies. Here, we want to introduce it to the volcanological community together with a new and user-friendly digital outcrop analysis methodology for inexperienced users. This tool may be useful, not only for volcano monitoring purposes, but also to describe the internal structure of exposed volcanic edifices or to estimate outcrop erosion rates that may be helpful in terms of hazard assessment or preservation of volcanic landscapes. We apply it to the Croscat volcano, a monogenetic cone in the La Garrotxa Volcanic Field (Catalan Volcanic Zone, NE Spain), quarrying of which leads to a perfect view of its interior but restricts access to its uppermost parts. Croscat is additionally one of the most emblematic symbols of the La Garrotxa Volcanic Field Natural Park, and its preservation is a main target of the park administration

    Ancient DNA Analysis of 8000 B.C. Near Eastern Farmers Supports an Early Neolithic Pioneer Maritime Colonization of Mainland Europe through Cyprus and the Aegean Islands

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    The genetic impact associated to the Neolithic spread in Europe has been widely debated over the last 20 years. Within this context, ancient DNA studies have provided a more reliable picture by directly analyzing the protagonist populations at different regions in Europe. However, the lack of available data from the original Near Eastern farmers has limited the achieved conclusions, preventing the formulation of continental models of Neolithic expansion. Here we address this issue by presenting mitochondrial DNA data of the original Near-Eastern Neolithic communities with the aim of providing the adequate background for the interpretation of Neolithic genetic data from European samples. Sixty-three skeletons from the Pre Pottery Neolithic B (PPNB) sites of Tell Halula, Tell Ramad and Dja'de El Mughara dating between 8,700–6,600 cal. B.C. were analyzed, and 15 validated mitochondrial DNA profiles were recovered. In order to estimate the demographic contribution of the first farmers to both Central European and Western Mediterranean Neolithic cultures, haplotype and haplogroup diversities in the PPNB sample were compared using phylogeographic and population genetic analyses to available ancient DNA data from human remains belonging to the Linearbandkeramik-Alföldi Vonaldiszes Kerámia and Cardial/Epicardial cultures. We also searched for possible signatures of the original Neolithic expansion over the modern Near Eastern and South European genetic pools, and tried to infer possible routes of expansion by comparing the obtained results to a database of 60 modern populations from both regions. Comparisons performed among the 3 ancient datasets allowed us to identify K and N-derived mitochondrial DNA haplogroups as potential markers of the Neolithic expansion, whose genetic signature would have reached both the Iberian coasts and the Central European plain. Moreover, the observed genetic affinities between the PPNB samples and the modern populations of Cyprus and Crete seem to suggest that the Neolithic was first introduced into Europe through pioneer seafaring colonization

    Empleo de herramientas virtuales para la creación de material didáctico de acceso libre

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    [SPA]Potenciar el aprendizaje autónomo del alumno siguiendo un determinado itinerario es uno de los postulados del denominado Plan Bolonia; en este contexto, además de otras funciones, el profesor ha de actuar como guía, enseñando y ayudando a alcanzar las habilidades y competencias marcadas como objetivos en cada materia. En algunos casos, esto significa la introducción paulatina de cambios en la metodología docente y la introducción de nuevas herramientas para facilitar el trabajo autónomo del alumno. Como profesores responsables de la experiencia piloto de adaptación al EEES de la materia Citología e Histología Vegetal y Animal iniciada en el año 2007 en la Universidad de Vigo, consideramos oportuno crear una herramienta propia para nuestro ámbito de conocimiento: un atlas histológico virtual. Asimismo, creímos que dicho atlas debía cumplir una serie de requisitos, tales como: abarcar la mayor parte de los aspectos relacionados con la Citología e Histología, disponer de gran cantidad de ilustraciones originales, ser fácil de usar, intuitivo y ameno, ser interactivo y potenciar el autoaprendizaje, diseñarse mediante programas de software libre, y ser de acceso y uso libre. [ENG]Promoting the autonomous learning of the students following a specific itinerary is one of the postulates of the so called Bologna Process; in this context, besides other functions, the professor should act as a guide, teaching and helping 2078 students to achieve the skills and competences marked like objectives in each subject. In some cases, this means a gradual introduction of changes in the teaching methodology and the introduction of new tools to facilitate the autonomous work of the students. As the responsible professors for the pilot experience of adaptation to the EEES of the matter Cytology and Animal and Plant Histology started in 2007 at the University of Vigo, we considered opportune to create our own tool for cell biology teaching: a virtual histological atlas. Likewise, we believed that the atlas should meet a series of requirements, such as: to cover most aspects of Cytology and Histology, to include a high number of original illustrations, to be easy to use, intuitive and mild (fun) pleasant, to be interactive and encourage self-learning, to be designed by free software, and to be of free access and use.Campus Mare Nostrum, Universidad Politécnica de Cartagena, Universidad de Murcia, Región de Murci

    Modeling magmatic accumulations in the upper crust: Metamorphic implications for the country rock

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    Field exposures of magma chambers tend to reveal contact metamorphic aureoles in the surrounding crust, which width varies from few centimeters to kilometers. The igneous accumulation not only increases the temperature around it, but also weakens its surrounding country rock beyond the brittle-ductile transition temperature. The formation of a ductile halo around the magmatic reservoir may significantly impact into the stability and growth of the magma chamber, as well as into potential dyke injections and processes of ground deformation. In this paper, we examine how a magmatic accumulation affects the country rock through the combination of petrologic and thermal perspectives. For this, we numerically modeled (i) the conductive cooling of an instantaneously emplaced magma chamber within compositionally representative pelitic and carbonate upper crusts, and (ii) the corresponding changes in the viscosity of the host rock potentially leading to ductile regimes. We consider basaltic to rhyolitic magma chambers at different depths with oblate, prolate and spherical geometries. The resulting temperature field distribution at different time steps is integrated with crustal metamorphic effects through phase diagram modeling. Our results indicate that the geometry of the magma accumulations plays a dominant role in controlling the local metamorphic and thermal effects on the country rocks. They conclude that (i) the combination of relatively simple geothermal models with petrologic datasets can generate first order predictions for the maximum metamorphic grade and geometry of magma chamber aureoles; (ii) the possible changes in the mechanical properties of the country rock are not necessarily linked to the petrological changes in contact aureoles; and (iii) the present rheologic outcomes may be used in further studies of magma chamber stability and integrity, which may favor the understanding of the melt transfer throughout the crust. © 2016 Elsevier B.V.AG is grateful for her Ramón y Cajal contract (RYC-2012-11024). A-V thanks the assistance of the “Ramón y Cajal” research program (RYC-2011-07584) and Programa Propio I (USal-2014). MD acknowledges the MISTI program (Massachusetts Institute of Technology [MIT] International Science and Technology Initiative) for fundingwork at the University of Salamanca in 2014.Peer reviewe

    Mitochondrial DNA genetic relationships at the ancient Neolithic site of Tell Halula

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    The extent of racemization of aspartic acid (Asp) -expressed as D/L ratio- has been used as a marker of biomolecular degradation in ancient remains. However, Asp racemization rate is highly variable, and depends on biochemical and geochemical factors. In this paper we aim to determine to which extent the fraction analyzed and the kind of sample used may influence the D/L Asp ratios. Other factors, such as burial site and sample preservation conditions, are also considered. D/L Asp ratios were obtained in 38 ancient human samples from 30 different individuals in which Real Time PCR quantification and amplification of short mtDNA fragments had been previously achieved. Four samples were taken from bones, 16 from whole teeth and 18 from dentine. In 7 cases whole tooth and dentine fractions from the same individual were analyzed. The samples belonged to 8 archaeological sites from Pre-pottery Neolithic B (PPNB), Cardial Neolithic and Chalcolithic time periods. Results show significant differences between the D/L Asp ratios obtained in dentine and whole tooth fractions from the same tooth and individual, as well as among dentine samples from the same archaeological site and among samples of the same age from different, though nearby, archaeological sites. Ancient DNA (aDNA) could be characterized in the majority of the samples, independently from their racemization values, which suggests that other factors, apart from the sample preservation stage, are more significantly affecting the racemization rate. A generalized use of the Asp racemization ratio as a threshold value for ancient DNA preservation needs to be questioned until further methodological standardization is considered

    Les ocupacions prehistòriques a les Coves de l'Aumediella (Benifallet) : una visió sintètica

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    Les coves de l'Aumediella, situades en un dels meandres del riu Ebre a l'alçada de Benifallet (Baix Ebre), han estat fruit de diverses troballes d'interès arqueològic, ben documentades des d'inicis del segle XX. El treballs centrats en el reestudi dels materials arqueològics recuperats, principalment ceràmica, lític i macrolític, ha aportat noves dades relacionades amb les activitats de freqüentació i ús d'aquest conjunt de 6 cavitats. En aquest sentit, el present article es centra en sintetitzar i contextualitzar les principals aportacions dels materials arqueològics recuperats amb l'objectiu contribuir al coneixement de les comunitats del VI-II mil·lenni al tram baix del riu Ebre.The Aumediella's caves, located in a meander of the Ebro River in its passage by Benifallet (Baix Ebre), have generated several findings of archaeological interest, well documented from the early twentieth century. This work is centered on the revision and restudying of this recovered archaeological remains, being them mainly pottery, lithic implements and grinding stones, and has provided new data related to the activities of frequentation and use of this set of six cavities. In this sense, this article is focused on synthetizing and contextualizing the main contributions of this archaeological remains in order to contribute to the knowledge of the 6th to 2n Millennium communities in the lower stretch of the Ebro River

    Podoplanin drives dedifferentiation and amoeboid invasion of melanoma

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    Melanoma is an aggressive skin cancer developing from melanocytes, frequently resulting in metastatic disease. Melanoma cells utilize amoeboid migration as mode of local invasion. Amoeboid invasion is characterized by rounded cell morphology and high actomyosin contractility driven by Rho GTPase signalling. Migrastatic drugs targeting actin polymerization and contractility are therefore a promising treatment option for metastatic melanoma. To predict amoeboid invasion and metastatic potential, biomarkers functionally linked to contractility pathways are needed. The glycoprotein podoplanin drives actomyosin contractility in lymphoid fibroblasts and is overexpressed in many cancers. We show that podoplanin enhances amoeboid invasion in melanoma. Podoplanin expression in murine melanoma drives rounded cell morphology, increasing motility, and invasion in vivo. Podoplanin expression is increased in a subset of dedifferentiated human melanoma, and in vitro is sufficient to upregulate melanoma-associated marker Pou3f2/Brn2. Together, our data define podoplanin as a functional biomarker for dedifferentiated invasive melanoma and a promising migrastatic therapeutic target

    Hedgehog Pathway Inhibition Hampers Sphere and Holoclone Formation in Rhabdomyosarcoma

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    Altres ajuts: This work was supported by grants from Institut Català d'Oncologia (ICO), Instituto de Salud Carlos III (RTICC-RD12/0036/0016 and RD12/0036/0027; PI11/00740 and PI14/00647), Fundació A. BOSCH, and ajuts predoctorals VHIR.Rhabdomyosarcoma (RMS) is the most common type of soft tissue sarcoma in children and can be divided into two main subtypes: embryonal (eRMS) and alveolar (aRMS). Among the cellular heterogeneity of tumors, the existence of a small fraction of cells called cancer stem cells (CSC), thought to be responsible for the onset and propagation of cancer, has been demonstrated in some neoplasia. Although the existence of CSC has been reported for eRMS, their existence in aRMS, the most malignant subtype, has not been demonstrated to date. Given the lack of suitable markers to identify this subpopulation in aRMS, we used cancer stem cell-enriched supracellular structures (spheres and holoclones) to study this subpopulation. This strategy allowed us to demonstrate the capacity of both aRMS and eRMS cells to form these structures and retain self-renewal capacity. Furthermore, cells contained in spheres and holoclones showed significant Hedgehog pathway induction, the inhibition of which (pharmacologic or genetic) impairs the formation of both holoclones and spheres. Our findings point to a crucial role of this pathway in the maintenance of these structures and suggest that Hedgehog pathway targeting in CSC may have great potential in preventing local relapses and metastases
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