151 research outputs found

    Niebla, de Oppidum a Madina

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    In this paper we study excavation results and studies carried out in the Niebla Ar-chaeological Urban Proyect. The relationship between the Niebla (Huelva province, southwest Spain) settlement and the configuration of an urban model from the Late Bronze Age to Medieval Time, explains the importance that the urban concept have been througth the time in the Huelva Countryside, and we analize the diferent eco-nomic interactive models beetwen the city and its territory.En este trabajo se estudian los resultados de las excavaciones y estudios realizados en el Proyecto de Arqueología Urbana en Niebla (Huelva). El papel desempeñado por el asentamiento de Niebla en la configuración de un modelo de ciudad con orígenes en el Bronce Final y su evolución a lo largo de las etapas preromana, romana y medieval, explica el rango que el concepto urbano ha tenido a lo largo de este periodo en la campiña de Huelva, y se analizan las causas que provocan los dis­tintos modelos por la interacción de relaciones económicas y sociales entre mundo urbano y su territorio

    Symmetrical Pyridinium-Phanes and –Diazacyclophanes — Promising Heterocyclic Scaffolds for the Development of Anti-Leishmanial Agents

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    There is an urgent need for better drugs for a more successful fight against leishmaniasis, one of the most important neglected diseases caused by the parasite Leishmania. We have recently synthesized several symmetrical pyridinium compounds belonging to two different series: bis-pyridinium and bis-quinolinium acyclic structures and bis-pyridinium diazacyclophanes derivatives. The first series of bis-pyridinium derivatives have been found to display activity against promastigotes and intracellular amastigotes of Leishmania donovani and Leishmania major, with EC50 values lower than 1 μM. The majority of compounds show a similar behavior in both Leishmania species, being slightly more active against intracellular amastigotes of L. major. The series of bis-pyridinium diazacyclophanes can be considered as rigid analogues of the previous bis-cationic ones. The activity of these compounds has also been evaluated against promastigotes and intracellular amastigotes of L. donovani and L. major. All the diazacyclophanes are more active against L. major, with EC50 values of between 1 and 17 μM in intracellular amastigotes, and in some cases they present a higher selectivity index than the reference anti-leishmanial drugs such as amphotericin B and miltefosine. In conclusion, these bis-quaternary compounds represent promising candidates as potential therapeutic agents against leishmaniasis

    Influencia del tamaño de pigmento en la distancia de detección del sparkle

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    XI Reunión Nacional de Óptica Día de la Luz; Facultad de Ciencias • Universidad de Salamanca 1 - 4 Septiembre, 2015; http://rno11.usal.es/programaSe diseñó un experimento psicofísico para evaluar la influencia del tamaño del pigmento de efecto en la distancia de detección del sparkle. Los resultados mostraron que a mayor tamaño de pigmento, mayor distancia de detección. Además, la correlación visual e instrumental (distancia de detección vs. grado de sparkle (SG)) sigue una relación lineal, sin embargo, no existe una relación lineal con el tamaño de pigmento: la distancia es máxima para un tamaño inferior al tamaño máximo.Peer Reviewe

    Conductance and application of organic molecule pairs as nanofuses

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    We propose that a pair of organic molecules can mimic the behavior of a macroscopic fuse at nanoscale, one component of the pair being the on state and the other the off state. For this task wemake use of density-functional theory to calculate the physical properties of selected molecules, which have also been synthesized by our team. By this means we obtain the transmission spectra and the current of the proposed devices, which allows us to compare the behavior of the on and off states.Of particular interest is the on/off switch ratios, defined as the current ratios of the on and off structures at the corresponding bias voltage. In a first stage, we examine the best linker between the device and the electrode for high on/off switch ratios. Once this is determined, we test the influence of the electron richness of the system to provide a high on/off switch ratio. The entire analysis is also supported by the molecular projected self-consistent Hamiltonian, which provides a good way of understanding the molecular behavior. All the calculations support that interesting on/off switch ratios of two orders of magnitude could be obtained with these prototypical nanofusesWe thank the Regional Government of Andalucía for financial support (Projects No. P06-FQM-01726 and No. P09-FQM-04571), the “Centro de Supercomputación de la Universidad de Granada,” and the “Centro de Computación Científica-UAM” for computation time. The authors are also grateful to the Spanish Secretaría de Estado de Universidades e Investigación, Ministerio de Educación y Ciencia, for financial support within research projects TEC2007-66812 and TEC2010-16211. N.F. thanks the Regional Government of Andalucía for her research contract, and LAC thanks the University of Granada for his research contrac

    A new roman fish-salting workshop in the Saltes Island (Tinto-Odiel Estuary, SW Spain): La Cascajera and its archaeological and geological context

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    The southwestern Atlantic coast of the Iberian Peninsula presents an important Roman heritage that includes numerous fish-salting workshops, with an industrial activity that went on for almost a millennium (1st century BC-7th century AD). Nevertheless, a future broad research is still necessary to determine the geologic substratum on which they are based, their palaeoenvironmental evolution, their main economic objectives and the byproducts derived from their activities. This paper is focused on the geology, dating and the archaeological record of La Cascajera, a new site located in the Tinto-Odiel estuary (SW Spain). This new cetaria occupied the northwestern end of La Cascajera ridge (Saltés Island), constituted by sandy, bioclastic deposits of previous washover fans (1st-2th centuries AD). During the main period of activity (middle of 4th century AD-5th century AD), the existence of a certain typology of amphorae as well as the documentation of a shell deposit formed mostly by Glycymeris suggest that this factory was oriented to the production of mixed fish sauces and the handling of edible bivalves. The main features of this deposit (texture, paleontology, taphonomy) could be used to differentiate middens from natural shelly ridges.La costa suratlántica de la Península Ibérica posee un importante legado romano que incluye numerosos talleres halieúticos, con una actividad que se desarrolló durante casi un milenio (siglo I a.C.-siglo VII d.C.). Sin embargo, se precisan nuevas investigaciones que determinen el contexto geológico en el que se desarrollaron, su evolución paleoambiental, sus principales objetivos económicos y los subproductos derivados de sus actividades. Este trabajo se centra en la geología, datación y registro arqueológico de La Cascajera, un nuevo yacimiento localizado en el estuario de los ríos Tinto y Odiel (S.O. de España). Esta nueva cetaria ocupaba el extremo noroccidental de la cresta de La Cascajera (Isla de Saltés), constituida por depósitos bioclásticos arenosos de abanicos de derrame previos (siglos I-II d.C.). Durante su principal periodo de actividad (mitad del siglo IV d.C.-siglo V d.C.), la existencia de una cierta tipología de ánforas así como la existencia de un conchero formado principalmente por Glycymeris sugieren que esta factoría estaba dedicada a la producción de salsas mixtas de pescado y la extracción de bivalvos comestibles. Las principales características de este conchero (textura, paleontología, tafonomía) podrían ser usadas para diferenciar concheros de acumulaciones naturales de conchas.Ministerio de Innovación, Ciencia y Empresa de España. Plan Nacional de I+D+i DEATLANTIR II-HAR2017-89154-PJunta de Andalucía-HUM-132, RNM-238 y RNM-29

    Two-dimensional carbon-based conductive materials with dynamically controlled asymmetric Dirac cones

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    The design of two dimensional graphene-type materials with an anisotropic electron flow direction in the X- and Y-axes opens the door for the development of novel electronic materials with multiple functions in nanoelectronics. In the present work, we have studied the electronic transport properties of a new family of 2D graphene-graphyne hybrids presenting conformationally free phenylethylene subunits. This system ensures two different conductive pathways that are perpendicular to each other: an acene nanoribbon subunit, in the X-axis, with graphene-type conduction, and a free to rotate phenylethylene subunit, in the Y-axis, in which the magnitude of the conduction depends dynamically on the corresponding torsion angle. Our calculations have confirmed that this system presents two different conduction pathways, which are related to the presence of asymmetric Dirac-type cones. Moreover, the Dirac cones can be dynamically modified in the presence of an external gate electrode, which is unprecedented in the literatureWe thank the MICINN (project CTQ-2011.22455) and the Regional Government of Andalucía (project P09-FQM-04571) for financial support and the ‘Centro de Supercomputación de la Universidad de Granada (UGRGRID-CSIRC)’ for computation time. NF and DM thank MICINN for their research contract

    Modelling the mid-late Holocene evolution of the Huelva Estuary and its human colonization, South-Western Spain

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    The major changes that occurred in the southwestern estuaries of the Spanish Atlantic coast during the last 6500 yr BP were simultaneous to human settlement and therefore the understanding of their coastal evolution will help interpreting human patterns in these areas. The study of the morpho-sedimentary features of new outcrops appearing in the middle sector of Saltés Island (Huelva Estuary, Spain) has been used to develop a model to understand the complex evolution of sand barriers than can be applied to similar inlets along the Atlantic Iberian coast. The first human settlements (6000–4000 yr BP) in the early Huelva Estuary (Tinto and Odiel rivers) were located in the ancient coastal banks or in the nearby hills. From 4000 yr BP onwards, the estuarine sediments started to emerge as sand barriers and chenier plains, prograding towards the mouth. As the littoral strands stabilized morphologically, they were colonized by human settlements in successive periods, the oldest inland (Almendral) and more recent outward (Cascajera). The study of the upper sedimentary layers of La Cascajera barrier display a tempestitic sequence of landward progradational washover-fans. The calibrated and modelled AMS dates in marine shells provide a storminess time range between the second half of first century BCE and the entire first century CE. Sedimentary records are useful to evaluate environmental changes, either from natural or anthropogenic causes, such as global and climate change. The interrelationship between the archaeological findings (mainly salting fish factories and old ports) and the morpho sedimentary evolution at the mouth of the Tinto and Odiel rivers allows us to highlight not only the Huelva Estuary's dynamics evolution, but also the possible regional patterns of human habitation from the beginning of the present sea-level highstand (middle Holocene).Ministerio de Economía y Competitividad CGL2010-15810/BTEEuropean Union (UE) EU Excellence Project of the Andalusia Board SEJ-477

    Efectos de diferentes tipos de fertilización sobre la alcachofa en reconversión a cultivo ecológico

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    En dos parcelas experimentales, una situada en el IVIA, en Moncada (Valencia) y otra en la fundación Caja Rural Valencia, en Paiporta (Valencia), hemos realizado sendos ensayos de fertilización. Los seis tratamientos del ensayo de Moncada han sido: testigo, dos de fertilización orgánica (a base de estiércol de ovino, y gallinaza, respectivamente), dos de fertilización organo- mineral y uno de fertilización mineral. Y en el de Paiporta hemos comparado tres tratamientos: fertilización orgánica (a base de estiércol de ovino), fertilización mineral y fertilización órgano-mineral. Las parcelas elementales con fertilización orgánica se han cultivado siguiendo técnicas de Agricultura Ecológica, mientras que en las de fertilización mineral y organo-mineral se han seguido prácticas de cultivo convencional. En la primera campaña de reconversión estudiada hemos constatado que la producción de capítulos de alcachofa resultó más baja con la fertilización orgánica que con la fertilización mineral u organo-mineral. El tipo de fertilización no afectó de forma significativa ni a la materia seca ni al contenido nutritivo de los capítulos. La variación temporal en el nivel de nitratos del suelo fue mayor que la debida al efecto tratamiento. La fertilización orgánica produjo una incidencia del barrenador de la alcachofa (Gortyna xanthenes ) más baja y un grado de parasitismo más alto que la fertilización mineral

    New strategies for colloidal-quantum-dot-based intermediate-band solar cells

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    The intermediate-band solar cell (IBSC) concept promises to increase the efficiency limit in a single-junction solar cell through the absorption of below-bandgap-energy photons. Despite their operating principle having been proposed over 20 years ago, IBSCs have not delivered on this promise yet, and the devices fabricated so far, mainly based on embedded epitaxial quantum dots, have instead operated with lower efficiency than conventional solar cells. A new paradigm, based on the exploitation as the intermediate band of the intragap states naturally occurring in the density functional theory description of colloidal (i.e., chemically synthesized) quantum dots, was suggested recently. Here, we revisit this intriguing concept unveiling its shortcomings and propose two alternative schemes: in the first, the localized electron surface trap states, ubiquitously found in commonly synthesized colloidal quantum dots, are used as intermediate bands in strongly coupled films made of small InAs nanocrystals and, in the second scheme, the intermediate band is provided by the conduction-band-minimum-derived miniband in films of larger InAs nanocrystals. Both schemes yield estimated limiting IBSC efficiencies exceeding Shockley-Queisser’s limit for a single absorber

    Ratones knock-out del receptor lpa1 de ácido lisofosfatídico presentan un acusado déficit de la isoenzima glutaminasa KGA (GLS) y una morfología alterada en las espinas dendríticas de hipocampo y corteza

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    Objectives: The objective of the present study was to utilize mice with knocked-down lysophosphatidic acid 1 (LPA1) receptor to ascertain changes in glutamatergic transmission that may help to explain part of the cognitive and memory deficits shown by these KO-LPA1 mice. Material & methods: A well characterized KO-LPA1 mouse strain was used as animal model and compared with wild-type (WT) and heterozygous animals. Expression studies were implemented by immunohistochemistry and Western analysis of mouse brain regions, real-time quantitative RT-PCR of GA isoforms, enzymatic analysis of regional GA activity and Golgi staining to assess dendritic spine morphology and density. Results: A strong reduction of KGA immunoreactivity was mostly revealed in cerebral cortex and hippocampus of KO-LPA1 mice versus WT and heterozygous animals. In contrast, neither mRNA levels nor enzyme activity were significantly altered in KO mice suggesting compensatory mechanisms for neurotransmitter Glu synthesis. Interestingly, Golgi staining of hippocampal and cortical neurons revealed a clear morphology change toward a less-mature undifferentiated spine phenotype, without changes in the total number of spines. Conclusions: The molecular mechanisms underlying KGA downregulation in null LPA1 mutant mice are unknown. However, LPA increases neuronal differentiation, arborization and neurite outgrowth of developing neurons, while Gln-derived Glu, through GA reaction, has been also involved in neuronal growth and differentiation. It is tempting to speculate that downregulation of KGA protein in KO-LPA1 mice induce morphological changes in dendritic spines of cortical and hippocampal neurons which, in turn, may account for memory and cognitive deficits shown by KO-LPA1 mice.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Acknowledgements: Red de Trastornos Adictivos, RTA, (RD12/0028/0013/) RETICS, ISCIII, y Consejería Innovación, Ciencia y Empresa, Junta de Andalucía (Proyecto de Excelencia CVI-6656)
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