1,280 research outputs found

    Analysis of a Celtiberian protective paste and its possible use by Arevaci warriors

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    This article presents an infrared spectroscopy and X-ray diffraction analysis of residue adhering to a Celtiberian pottery sherd of late Iron Age date from the Arevacian site of Cerro del Castillo, in AyllĂłn (Segovia, Spain). This residue may be a paste used since antiquity for protective aims. Orange-sepia in colour, made from crushed bones and glue, the paste was used by Greeks and Romans and later in the construction of the cathedrals and monasteries of Europe to confer a warm colour to the stone and to protect it against environmental deterioration. In this article we also suggest a possible ritual use of this paste in the protection of the skin of the Arevaci and Edetani warriors, and the previously unreported pleasant aroma of this material is highlighted. The possible nutritional use of this paste is also considered

    Sobre las aguas minerales naturales de España: Asociaciones entre su composición química y localización geográfica

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    A comparative study of the natural mineral waters of Spain, accomplished through the chemical composition of the packed waters, it has carried us to warn  a series of observations that put on relationship the composition of the water with the geographical situation of the springs. Of special interest are the latitude-salinity and longitude-mineralization associations, not reported previouslyUn estudio comparativo de las aguas minerales naturales de España, realizad oa través de la composición de las aguas envasadas, nos ha llevado a advertir una serie de observaciones que ponen en relación dichas composiciones con la situación geográfica de los manantiales. De especial interés son las asociaciones latitud-salinidad y longitud-mineralización, no referidas anteriormente

    Physico-chemical study of an exogenic fulgurite from a thunderstorm on 10th August 2013 in Dallas, TX

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    Droplet-like exogenic fulgurites comprise a minor grouplet of natural glasses resulting from powerful lightning strikes. Reports on such type-V fulgurites are scarce in the literature. In this work, a fulgurite specimen from the thunderstorm that took place on 10th August 2013, in Dallas, TX, USA, has been analyzed using X-ray powder diffraction, X-ray fluorescence, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and infrared and Raman spectroscopy techniques. X-ray diffraction revealed the amorphous nature of the exofulgurite, and X-ray fluorescence showed a high Si, Al and Ca content. Infrared and Raman spectroscopy were key in revealing clear Si–O modes related signatures and a very significant presence of water (OH/H2O). A parallel with glassy silicate materials, but also with opal-A, was essential in the understanding of the fulgurite’s characteristics. In particular, Raman data evidenced the exofulgurite to have a high degree of depolymerization

    Potential control of forest diseases by solutions of chitosan oligomers, propolis and nanosilver

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    There is a growing necessity to replace chemical agents with ecofriendly materials, arising from the impact on the environment and/or human health, which calls for the design of new broad-spectrum fungicides. In this work, chitosan oligomers (COs), propolis (Ps) and silver nanoparticles (AgNPs) mixtures in solution were assessed to control the growth of different phytopathogenic fungi and oomycetes in vitro. Binary solutions of COs-Ps and COs-AgNPs evinced the highest antifungal effect against Fusarium circinatum and Diplodia pinea fungi, respectively, with a ca. 80% reduction in their mycelial growth. The COs solution by itself also proved to be greatly effective against Gremmeniella abietina, Cryphonectria parasitica and Heterobasidion annosum fungi, causing a reduction of 78%, 86% and 93% in their growth rate, respectively. Likewise, COs also attained a 100% growth inhibition on the oomycete Phytophthora cambivora. On the other hand, Ps inhibited totally the growth of Phytophthora Ă—alni and Phytophthora plurivora. The application of AgNPs reduced the mycelial growth of F. circinatum and D. pinea. However, the AgNPs in some binary and ternary mixtures had a counter-productive effect on the anti-fungal/oomycete activity. In spite of the fact that the anti-fungal/oomycete activity of the different treatments showed a dependence on the particular type of microorganism, these solutions based on natural compounds can be deemed as a promising tool for control of tree diseases

    Cyttaria hariotii E.Fisch. as a promising source of pullulan and Mn(II)-pullulan complexes for Mn-deficiency remediation in winter cereals

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    Pullulan, a water-soluble polysaccharide consisting of maltotriose units used in the preparation of edible films and drug delivery, is generally produced from starch by Aureobasidium pullulans (de Bary & Löwenthal) G.Arnaud fungus. In this article, the characterisation of an alternative pullulan source - the stromata of Cyttaria hariotii E.Fisch. fungus - by elemental analysis, infrared spectroscopy and thermal analysis techniques is reported. With a view to a possible valorisation of this pullulan and its derivatives as bioactive formulations in agriculture, low-molecular-weight pullulan (<7 kDa) complexes with Mn(II), suitable for the remediation of Mn-deficiencies in winter cereal by foliar application, were synthesised and characterised by mass spectrometry

    Research on nonlinear and quantum optics at the photonics and quantum information group of the University of Valladolid

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    We outline the main research lines in Nonlinear and Quantum Optics of the Group of Photonics and Quantum Information at the University of Valladolid. These works focus on Optical Solitons, Quantum Information using Photonic Technologies and the development of new materials for Nonlinar Optics. The investigations on optical solitons cover both temporal solitons in dispersion managed fiber links and nonparaxial spatial solitons as described by the Nonlinear Helmholtz Equation. Within the Quantum Information research lines of the group, the studies address new photonic schemes for quantum computation and the multiplexing of quantum data. The investigations of the group are, to a large extent, based on intensive and parallel computations. Some associated numerical techniques for the development of the activities described are briefly sketched

    Accurate circuit analysis of resonant-type left handed transmission lines with inter-resonator coupling

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    In this paper, a circuit model for the description of left handed transmission lines based on complementary split rings resonators CSRRs is proposed. As compared to previous models, coupling between adjacent resonators is included in the present work. The conditions that make this coupling significant are discussed. Specifically, it will be shown that it is barely present when circular CSRRs are used to implement the left handed transmission line. However, if the line is loaded with rectangular CSRRs separated by a small distance, inter-resonator coupling is important and it significantly influences the electromagnetic behavior of the structures. It will be also shown that under low or moderate coupling, it is possible to describe the structures by means of a simplified model with modified parameters. Several prototype devices with different CSRR topologies and coupling levels have been fabricated to illustrate the phenomenology associated with these structures and the accuracy of their model descriptions. The results of this work can be of interest for the design of planar microwave circuits based on CSRR left handed lines.Ministerio de Economía y Ciencias de España-TEC2004-04249-C02-01 y TEC2004-04249-C02-02Comisión Europea (Red de Excelencia)-E 500252-2 METAMORPHOS

    Anderson localization in a periodic photonic lattice with a disordered boundary

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    We investigate experimentally the light evolution inside a two-dimensional finite periodic array of weakly- coupled optical waveguides with a disordered boundary. For a completely localized initial condition away from the surface, we find that the disordered boundary induces an asymptotic localization in the bulk, centered around the initial position of the input beam.Comment: 3 pages, 4 figure

    UtilizaciĂłn de metil jasmonato para la inducciĂłn de resistencia ante Fusarium oxysporum, F. circinatum y Ophiostoma novo-ulmi

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    Damping off is probably the most common disease affecting seedlings in forest nurseries. In south-western Europe, the pitch canker and the Dutch elm disease cause relevant economic looses in forests, mostly in adult trees. The ability of the chemical plant elicitor methyl jasmonate (MeJA) to induce resistance in Pinus pinaster against Fusarium oxysporum and F. circinatum, and in Ulmus minor against Ophiostoma novo-ulmi was examined. In a first experiment, an aqueous solution of MeJA 5 mM was applied to P. pinaster seeds by immersion or spray, and different concentrations of MeJA (0, 0.1, 0.5, 1, 5 and 10 mM) were tested in seedlings before inoculations with F. oxysporum (105 and 107 spores mL–1). In a second experiment, 6-months-old P. pinaster seedlings were sprayed with 0 and 25 mM of MeJA, and later challenged with mycelium of F. circinatum. Finally, 4-year-old U. minor trees were sprayed with 0, 50 and 100 mM of MeJA and subsequently inoculated with O. novo-ulmi (106 spores mL–1). MeJA did not protect P. pinaster seeds and seedlings against F. oxysporum, probably because plants were too young for the physiological mechanisms responsible for resistance to be induced. Based on the morphological changes observed in the treated 6-months-old P. pinaster seedlings (reduction of growth and increased resin duct density), there is evidence that MeJA could have activated the mechanisms of resistance. However, 25 mM MeJA did not reduce plant mortality, probably because the spread of the virulent F. circinatum strain within the tree tissues was faster than the formation of effective defense responses. Based on the lack of phenological changes observed in the treated elms, there is no evidence that MeJA would cause induction of resistance. These results suggest that the use of MeJA to prevent F. oxysporum and F. circinatum in P. pinaster seedlings in nurseries and O. novo-ulmi in U. minor trees should be discarded.El “damping off” es una de las enfermedades más comunes en los viveros forestales. En árboles adultos del suroeste de Europa, el chancro resinoso y la grafiosis del olmo son enfermedades que están causando importantes pérdidas económicas en los bosques. Se ha estudiado la capacidad del metil jasmonato (MeJA), un elicitador químico de plantas, para inducir resistencia en Pinus pinaster ante Fusarium oxysporum y F. circinatum, y en Ulmus minor ante Ophiostoma novo-ulmi. En un primer experimento se aplicó una solución acuosa de MeJA 5 mM a semillas de P. pinaster mediante inmersión o pulverización de las mismas, y diferentes concentraciones de MeJA (0, 0.1, 0.5, 1, 5 and 10 mM) fueron pulverizadas en plántulas de P. pinaster antes de las inoculaciones con F. oxysporum (105 y 107 esporas mL–1). En un segundo experimento, plántulas de P. pinaster de 6 meses de edad fueron pulverizadas con MeJA 0 y 25 mM, y posteriormente inoculadas con micelio de F. circinatum. Por último, brinzales de U. minor de 4 años de edad fueron pulverizados con MeJA a 0, 50 y 100 mM e inmediatamente inoculados con O. novo-ulmi (106 esporas mL–1). El MeJA no protegió a las semillas ni a las plántulas de P. pinaster ante F. oxysporum, quizá debido a que las plántulas eran demasiado jóvenes para inducir los mecanismos fisiológicos responsables de la resistencia. Basándonos en los cambios morfológicos observados en las plántulas de 6 meses de P. pinaster (reducción del crecimiento e incremento de la densidad de los canales resiníferos), hay evidencia de que el MeJA pudo haber activado los mecanismos de resistencia. El MeJA a 25 mM no consiguió reducir la mortalidad probablemente porque la dispersión de F. circinatum en el interior de los tejidos fue más rápida que la formación de respuestas defensivas efectivas. Basándonos en la falta de cambios fenológicos de los olmos tratados, no hay evidencias de que el MeJA pueda haber causado una inducción de resistencia. Los resultados sugieren que el uso del MeJA para prevenir los patógenos F. oxysporum y F. circinatum en plántulas de P. pinaster en viveros y O. novo-ulmi en brinzales de U. minor debe ser descartado

    Universal Conductance Distributions in the Crossover between Diffusive and Localization Regimes

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    The full distribution of the conductance P(G)P(G) in quasi-one-dimensional wires with rough surfaces is analyzed from the diffusive to the localization regime. In the crossover region, where the statistics is dominated by only one or two eigenchannels, the numerically obtained P(G) is found to be independent of the details of the system with the average conductance as the only scaling parameter. For < e^2/h, P(G) is given by an essentially ``one-sided'' log-normal distribution. In contrast, for e^2/h <= 2e^2/h, the shape of P(G) remarkable agrees with those predicted by random matrix theory for two fluctuating transmission eigenchannels.Comment: Accepted for publication in Phys. Rev. Let
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