102 research outputs found

    Foundations for the Design of a Creative System Based on the Analysis of the Main Techniques that Stimulate Human Creativity

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    This work presents the design of a computational system with creative capacity, based on the synthesis of the main methods that stimulate human creativity. When analyzing each method, a set of characteristics that the computer system must have in order to emulate a creative capacity has been suggested. In this way, by integrating all the suggestions in a structured way, it is possible to design the general architecture and functioning strategy of a computer system that has the incremental creative capacity of well-known creative methods. This computational system is designed as a multi-agent system, made up of two groups of agents, the problem solving group and the creative group, the first one exploring and evaluating paths for suitable solutions, the second implementing creative methods to generate new paths that are provided to the first group

    Renormalization group equations in resonance chiral theory

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    The use of the equations of motion and meson field redefinitions allows the development of a simplified resonance chiral theory lagrangian: terms including resonance fields and a large number of derivatives can be reduced into corresponding O(p2) resonance operators, containing the lowest possible number of derivatives. This is shown by means of the explicit computation of the pion vector form-factor up to next-to-leading order in 1/Nc. The study of the renormalization group equations for the corresponding couplings demonstrates the existence of an infrared fixed point in the resonance theory. The possibility of developing a perturbative 1/Nc expansion in the slow running region around the fixed point is shown here.Comment: 6 pages, 3 figures. Final version as published. References added. Extended explanations. The interrelation between the IR fixed point and the UV constraints has been further studie

    Tracing sulfate recycling in the hypersaline Pétrola lake (SE Spain): A combined isotopic and microbiological approach

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    Sulfur (S) plays a significant role in saline environments, and sulfate (SO4 2−) is an important component of the biogeochemical S-cycle since it acts as the main electron acceptor in anoxic sediments. The purpose of this paper is to evaluate the fate of S, its origin, and processes affecting sulfate outcome in the hypersaline Pétrola Lake in the Castilla-La Mancha region (High Segura Basin, SE Spain). The lake is the terminal discharge zone of an endorheic basin with considerable anthropogenic pressures. Anthropogenic activities (mainly agricultural inputs and wastewater discharge), together with bedrock leaching of sulfate and sulfide-rich sediments, increase dissolved SO4 2− in surface and groundwater up to 123,000 mg/L. The source and fate of sulfate in this environment was investigated coupling hydrochemistry, including hydrogen sulfide (H2S) microprofiles, isotopic analyses (δ34S, δ18OSO4, δ2HH2O, δ18OH2O, and tritium), mineralogical determinations, and molecular biology tools (16S rDNA amplification and sequencing). The origin of dissolved SO4 2− in water is related to pyrite oxidation from Lower Cretaceous sediments, and secondary gypsum dissolution. Under the lake, dissolved SO4 2− decreases with depth, controlled by three main processes: (1) seasonal evaporation cycles, (2) hydrodynamic instability caused by the different density-driven groundwater flow, and (3) sulfate-reduction processes, i.e. dissimilatory bacterial sulfate reduction (BSR). These processes control the continuous recycling of sulfur in the system. Lake water and groundwater are in hydraulic connection, and a density-driven flow (DDF) is able to transport reactive organic matter and dissolved SO4 2− towards the underlying aquifer. Hydrochemical evolution in depth, H2S production (up to 0.024 nmol/cm3·s) and the presence of sulfate-reducing bacteria suggest the existence of BSR processes. However, isotope techniques are insufficient to elucidate BSR processes since their isotopic effect is masked by low isotope fractionation and high SO4 2− concentrations. The pattern here described may be found in other saline basins worldwide

    A Multi-isotopic approach to investigate the influence of land use on nitrate removal in a highly saline lake-aquifer system

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    Endorheic or closed drainage basins in arid and semi-arid regions are vulnerable to pollution. Nonetheless, in the freshwater-saltwater interface of endorheic saline lakes, oxidation-reduction (redox) reactions can attenuate pollutants such as nitrate (NO3- ). This study traces the ways of nitrogen (N) removal in the Pétrola lake- aquifer system (central Spain), an endorheic basin contaminated with NO3- (up to 99.2 mg/L in groundwater). This basin was declared vulnerable to NO3- pollution in 1998 due to the high anthropogenic pressures (mainly agriculture and wastewaters). Hydrochemical, multi-isotopic (δ18ONO3, δ15NNO3, δ13CDIC, δ18OH2O, and δ2HH2O) and geophysical techniques (electrical resistivity tomography) were applied to identify the main redox processes at the freshwater-saltwater interface. The results showed that the geometry of this interface is influenced by land use, causing spatial variability of nitrogen biogeochemical processes over the basin. In the underlying aquifer, NO3- showed an average concentration of 38.5 mg/L (n = 73) and was mainly derived from agricultural inputs. Natural attenuation of NO3- was observed in dryland farming areas (up to 72%) and in irrigation areas (up to 66%). In the Pétrola Lake, mineralization and organic matter degradation in lake sediment play an important role in NO3- reduction. Our findings are a major step forward in understanding freshwater-saltwater interfaces as reactive zones for NO3- attenuation. We further emphasize the importance of including a land use perspective when studying water quality-environmental relationships in hydrogeological systems dominated by density- driven circulation

    Denitrification in a hypersaline lake–aquifer system (Pétrola Basin, Central Spain): The role of recent organic matter and Cretaceous organic rich sediments

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    Agricultural regions in semi-arid to arid climates with associated saline wetlands are one of the most vulnerable environments to nitrate pollution. The Pétrola Basin was declared vulnerable to NO3 − pollution by the Regional Government in 1998, and the hypersaline lake was classified as a heavily modified body of water. The study assessed groundwater NO3 − through the use of multi-isotopic tracers (δ15N, δ34S, δ13C, δ18O) coupled to hydrochemistry in the aquifer connected to the eutrophic lake. Hydrogeologically, the basin shows two main flow components: regional groundwater flow from recharge areas (Zone 1) to the lake (Zone 2), and a density-driven flow from surface water to the underlying aquifer (Zone 3). In Zones 1 and 2, δ15NNO3 and δ18ONO3 suggest that NO3 − from slightly volatilized ammonium synthetic fertilizers is only partially denitrified. The natural attenuation of NO3 − can occur by heterotrophic reactions. However, autotrophic reactions cannot be ruled out. In Zone 3, the freshwater–saltwater interface (down to 12–16 m below the ground surface) is a reactive zone for NO3 − attenuation. Tritium data suggest that the absence of NO3 − in the deepest zones of the aquifer under the lake can be attributed to a regional groundwater flow with long residence time. In hypersaline lakes the geometry of the density-driven flow can play an important role in the transport of chemical species that can be related to denitrification processes.Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUECastilla–La Mancha GovernmentSpanish GovernmentCatalan Governmentpu

    Quantum Loops in the Resonance Chiral Theory: The Vector Form Factor

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    We present a calculation of the Vector Form Factor at the next-to-leading order in the 1/N_C expansion, within the framework of Resonance Chiral Theory. The calculation is performed in the chiral limit, and with two dynamical quark flavours. The ultraviolet behaviour of quantum loops involving virtual resonance propagators is analyzed, together with the kind of counterterms needed in the renormalization procedure. Using the lowest-order equations of motion, we show that only a few combinations of local couplings appear in the final result. The low-energy limit of our calculation reproduces the standard Chiral Perturbation Theory formula, allowing us to determine the resonance contribution to the chiral low-energy couplings, at the next-to-leading order in 1/N_C, keeping a full control of their renormalization scale dependence.Comment: 27+1 pages, 9 figure

    Spin-1 Correlators at Large NC: Matching OPE and Resonance Theory up to O(alpha_s)

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    The relation between the quark-gluon description of QCD and the hadronic picture is studied up to order alpha_s. The analysis of the spin-1 correlators is developed within the large NC framework. Both representations are shown to be equivalent in the euclidean domain, where the Operator Product Expansion is valid. By considering different models for the hadronic spectrum at high energies, one is able to recover the alpha_s running in the correlators, to fix the rho(770) and a1(1260) couplings, and to produce a prediction for the values of the condensates. The Operator Product Expansion is improved by the large NC resonance theory, extending its range of validity. Dispersion relations are employed in order to study the minkowskian region and some convenient sum rules, specially sensitive to the resonance structure of QCD, are worked out. A first experimental estimate of these sum rules allows a cross-check of former determinations of the QCD parameters and helps to discern and to discard some of the considered hadronical models. Finally, the truncated resonance theory and the Minimal Hadronical Approximation arise as a natural approach to the full resonance theory, not as a model.Comment: 36 pages, 19 figures. Minor changes (added reference,...). Paper as finally appeared in pres

    Biología molecular de la asimilación de nitrato en algas

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    El alga verde eucariótica Chlamydomonas reinhardtii es un organismo modelo para el estudio de la biología molecular de la asimilación de nitrato. Este sistema biológico presenta excelentes cualidades para estudios bioquímicos, fisiológicos, genéticos y moleculares. Estas investigaciones han permitido los siguientes logros: i) generación de una colección de mutantes; ii) identificación y caracterización de genes para el transporte de amonio; iii) caracterización de genes del transporte biespecífico de bicarbonato/nitrito; iv) clonación y caracterización del gen que codifica la proteína portadora de cofactor de molibdeno (MCP), determinación de la estructura cristalina de la misma y de sus residuos funcionales en la unión del cofactor; v) utilización de una nueva estrategia para identificar mutantes del cofactor de molibdeno; y vi) identificación de un nuevo LTR-retrotransposón de la familia gypsy

    Compilation of parameterized seismogenic sources in Iberia for the SHARE European-scale seismic source model.

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    Abstract: SHARE (Seismic Hazard Harmonization in Europe) is an EC-funded project (FP7) that aims to evaluate European seismic hazards using an integrated, standardized approach. In the context of SHARE, we are compiling a fully-parameterized active fault database for Iberia and the nearby offshore region. The principal goal of this initiative is for fault sources in the Iberian region to be represented in SHARE and incorporated into the source model that will be used to produce seismic hazard maps at the European scale. The SHARE project relies heavily on input from many regional experts throughout the Euro-Mediterranean region. At the SHARE regional meeting for Iberia, the 2010 Working Group on Iberian Seismogenic Sources (WGISS) was established; these researchers are contributing to this large effort by providing their data to the Iberian regional integrators in a standardized format. The development of the SHARE Iberian active fault database is occurring in parallel with IBERFAULT, another ongoing effort to compile a database of active faults in the Iberian region. The SHARE Iberian active fault database synthesizes a wide range of geological and geophysical observations on active seismogenic sources, and incorporates existing compilations (e.g., Cabral, 1995; Silva et al., 2008), original data contributed directly from researchers, data compiled from the literature, parameters estimated using empirical and analytical relationships, and, where necessary, parameters derived using expert judgment. The Iberian seismogenic source model derived for SHARE will be the first regional-scale source model for Iberia that includes fault data and follows an internationally standardized approach (Basili et al., 2008; 2009). This model can be used in both seismic hazard and risk analyses and will be appropriate for use in Iberian- and European-scale assessments

    Analysis of norfloxacin ecotoxicity and the relation with its degradation by means of electrochemical oxidation using different anodes

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    [EN] In this work, ecotoxicological bioassays based on Lactuca sativa seeds and bioluminescent bacterium (Vibrio fischeri) have been carried out in order to quantify the toxicity of Norfloxacin (NOR) and sodium sulfate solutions, before and after treating them using electrochemical advanced oxidation. The effect of some process variables (anode material, reactor configuration and applied current) on the toxicity evolution of the treated solution has been studied. A NOR solution shows an EC50 (5 days) of 336 mg L-1 towards Lactuca sativa. This threshold NOR concentration decreases with sodium sulfate concentration, in solutions that contain simultaneously Norfloxacin and sodium sulfate. In every case considered in this work, the electrochemical advanced oxidation process increased the toxicity (towards both Lactuca sativa and Vibrio fischeri) of the solution. This toxicity increase is mainly due to the persulfate formation during the electrochemical treatment. From a final solution toxicity point of view, the best results were obtained using a BDD anode in a divided reactor applying the lowest current intensity.The authors are very grateful to the Ministerio de Economia y Competitividad (Projects CTQ2015-65202-C2-1-R and RTI2018-101341-B-C21) for their economic support.Montañés, M.; García Gabaldón, M.; Roca-Pérez, L.; Giner-Sanz, JJ.; Mora-Gómez, J.; Pérez-Herranz, V. (2020). Analysis of norfloxacin ecotoxicity and the relation with its degradation by means of electrochemical oxidation using different anodes. Ecotoxicology and Environmental Safety. 188:1-10. https://doi.org/10.1016/j.ecoenv.2019.109923S110188Banks, M. K., & Schultz, K. E. (2005). Comparison of Plants for Germination Toxicity Tests in Petroleum-Contaminated Soils. Water, Air, and Soil Pollution, 167(1-4), 211-219. doi:10.1007/s11270-005-8553-4Barreto, J. P. d. P., Araujo, K. C. d. F., de Araujo, D. M., & Martinez-Huitle, C. A. (2015). 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