482 research outputs found

    Antiferromagnetism in four dimensions: search for non-triviality

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    We present antiferromagnetism as a mechanism capable of modifying substantially the phase diagram and the critical behaviour of statistical mechanical models. This is particularly relevant in four dimensions, due to the connection between second order transition points and the continuum limit as a quantum field theory. We study three models with an antiferromagnetic interaction: the Ising and the O(4) Models with a second neighbour negative coupling, and the \RP{2} Model. Different conclusions are obtained depending on the model.Comment: 4 pages LateX. Contribution to Lat9

    A unified approach to Poisson-Hopf deformations of Lie-Hamilton systems based on sl(2)

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    Producción CientíficaBased on a recently developed procedure to construct Poisson-Hopf deformations of Lie–Hamilton systems, a novel unified approach to nonequivalent deformations of Lie–Hamilton systems on the real plane with a Vessiot–Guldberg Lie algebra isomorphic to sl(2) is proposed. This, in particular, allows us to define a notion of Poisson–Hopf systems in dependence of a parameterized family of Poisson algebra representations. Such an approach is explicitly illustrated by applying it to the three non-diffeomorphic classes of sl(2) Lie–Hamilton systems. Our results cover deformations of the Ermakov system, Milne–Pinney, Kummer–Schwarz and several Riccati equations as well as of the harmonic oscillator (all of them with t-dependent coefficients). Furthermore t-independent constants of motion are given as well. Our methods can be employed to generate other Lie–Hamilton systems and their deformations for other Vessiot–Guldberg Lie algebras and their deformations

    Nanostructures liquids based on octanoic acid vesicles to extract PAHs in food

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    II Encuentro sobre nanociencia y nanotecnología de investigadores y tecnólogos de la Universidad de Córdoba. NANOUC

    Influence of process variables on the kinetic parameters of a Langmuir-Hinshelwood expression for E.coli inactivation during the photocatalytic disinfection of water

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    This research describes the effect of the photocatalyst concentration, irradiation power, concentration of inorganic salts and the initial pH on the three parameters of a Langmuir-Hinshelwood-model: inactivation kinetic constant; k, dimensionless interaction coefficient; K*, and inhibition coefficient; n, which was applied to the photocatalytic disinfection of water with TiO2. In general, there is a qualitative finding in the effects on parameters of some variables since an increase in k was always related to a decrease in K*. Such relation was observed for the amount of TiO2, the irradiation power and the increase in concentration of inorganic salts: NaCl and CaCO3. Moreover, increase in MgSO4 concentration do not cause a tendency of change on the described parameters. As for pH of the reaction media, an increasing effect on k is observed when its value promotes proximity between bacteria and TiO2 particles. Finally, small changes were observed for n with the studied variables, but indeed significant for mathematical fitting. Thus, these findings led to the formulation of a mathematical description of the effects of the most important variables and their interactions on the kinetic parameters. This last hypothesis was validated by comparison of experimental and predicted data with high correlations

    Analysing the impact of climate change on hydrological ecosystem services in laguna del sauce (Uruguay) using the swat model and remote sensing data

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    Assessing how climate change will affect hydrological ecosystem services (HES) provision is necessary for long-term planning and requires local comprehensive climate information. In this study, we used SWAT to evaluate the impacts on four HES, natural hazard protection, erosion control regulation and water supply and flow regulation for the Laguna del Sauce catchment in Uruguay. We used downscaled CMIP-5 global climate models for Representative Concentration Pathways (RCP) 2.6, 4.5 and 8.5 projections. We calibrated and validated our SWAT model for the periods 2005 2009 and 2010 2013 based on remote sensed ET data. Monthly NSE and R2 values for calibration and validation were 0.74, 0.64 and 0.79, 0.84, respectively. Our results suggest that climate change will likely negatively affect the water resources of the Laguna del Sauce catchment, especially in the RCP 8.5 scenario. In all RCP scenarios, the catchment is likely to experience a wetting trend, higher temperatures, seasonality shifts and an increase in extreme precipitation events, particularly in frequency and magnitude. This will likely affect water quality provision through runoff and sediment yield inputs, reducing the erosion control HES and likely aggravating eutrophication. Although the amount of water will increase, changes to the hydrological cycle might jeopardize the stability of freshwater supplies and HES on which many people in the south-eastern region of Uruguay depend. Despite streamflow monitoring capacities need to be enhanced to reduce the uncertainty of model results, our findings provide valuable insights for water resources planning in the study area. Hence, water management and monitoring capacities need to be enhanced to reduce the potential negative climate change impacts on HES. The methodological approach presented here, based on satellite ET data can be replicated and adapted to any other place in the world since we employed open-access software and remote sensing data for all the phases of hydrological modelling and HES provision assessment. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.This work has received funding from the European Union’s Horizon 2020 research and innovation programme within the framework of the project SMARTLAGOON under grant agreement No. 101017861. This study was also supported by the State Research Agency of Spain through the excellence certification María de Maeztu (Ref. MDM-2017-0714). Celina Aznarez was supported by the Doctoral INPhINIT–INCOMING program, fellowship code (LCF/BQ/DI20/11780004), from “la Caixa” Foundation (ID 100010434). Javier Senent-Aparicio was supported by the training grant (21201/EE/19) awarded by the Séneca Foundation in the framework of the Jimenez de la Espada Mobility, Cooperation and Internationalization Program. Adrián López-Ballesteros was supported by the Spanish Ministerio de Educación, Cultura y Deporte with an FPU grant (FPU17/00923). Juan Pablo Pacheco was supported by the Sino-Danish Center–Aarhus University, the University of the Chinese Academy of Sciences and the University of the Republic, Uruguay. This work has received funding from the European Union?s Horizon 2020 research and innovation programme within the framework of the project SMARTLAGOON under grant agreement No. 101017861. This study was also supported by the State Research Agency of Spain through the excellence certification Mar?a de Maeztu (Ref. MDM-2017-0714). Celina Aznarez was supported by the Doctoral INPhINIT?INCOMING program, fellowship code (LCF/BQ/DI20/11780004), from ?la Caixa? Foundation (ID 100010434). Javier Senent-Aparicio was supported by the training grant (21201/EE/19) awarded by the S?neca Foundation in the framework of the Jimenez de la Espada Mobility, Cooperation and Internationalization Program. Adri?n L?pez-Ballesteros was supported by the Spanish Ministerio de Educaci?n, Cultura y Deporte with an FPU grant (FPU17/00923). Juan Pablo Pacheco was supported by the Sino-Danish Center?Aarhus University, the University of the Chinese Academy of Sciences and the University of the Republic, Uruguay. The authors acknowledge Paper Check Proofreading and Editing Services for proofreading the manuscript

    Particle release fromrefit operations in shipyards: Exposure, toxicity and environmental implications

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    European harbours are known to contribute to air quality degradation.While most of the literature focuses on emissions from stacks or logistics operations, ship refit and repair activities are also relevant aerosol sources in EU harbour areas. Main activities include abrasive removal of filler and spray painting with antifouling coatings/primers/topcoats. This work aimed to assess ultrafine particle (UFP) emissions from ship maintenance activities and their links with exposure, toxicity and health risks for humans and the aquatic environment. Aerosol emissions were monitored during mechanical abrasion of surface coatings under real-world operating conditions in two scenarios in the Mallorca harbour (Spain). Different types of UFPs were observed: (1) highly regular (triangular, hexagonal) engineered nanoparticles (Ti-, Zr-, Fe-based), embedded as nano-additives in the coatings, and (2) irregular, incidental particles emitted directly or formed during abrasion. Particle number concentrationsmonitored were in the range of industrial activities such as drilling or welding (up to 5 ∗ 105/cm3, mean diameters <30 nm). The chemical composition of PM4 aerosols was dominated by metallic tracers in the coatings (Ti, Al, Ba, Zn). In vitro toxicity of PM2 aerosols evidenced reduced cell viability and a moderate potential for cytotoxic effects. While best practices (exhaust ventilation, personal protective equipment, dust removal) were in place, it is unlikely that exposures and environmental release can be fully avoided at all times. Thus, it is advisable that health and safety protocols should be comprehensive to minimise exposures in all types of locations (near- andfar-field) and periods (activity and non-activity). Potential release to coastal surface waters of metallic engineered and incidental nanomaterials, as well as fine and coarse particles (in the case of settled dust), should be assessed and avoided

    Software público, libre, abierto, gratuito, privativo y comercial para la innovación y mejora de la calidad en la docencia, investigación, gestión y asistencia

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    The public free software (now renamed as open software) is the basis of the open source software (OSS) project. This initiative promotes the use of open standards and platform-independent accessibility. Many OSS products are free or low cost, which allows their deployment even in the absence of large economic resources (developing countries, schools, etc.). Besides, their source code can be modified, adapted and optimized by anyone, since it is public. Nevertheless, the OSS may also have drawbacks. Thus, its development may not be as orderly and hierarchical as the privative software is, and may not have an appropriate funding. This may jeopardize the ease of use and coherence of the final product, increasing the transition, training and technical support costs. Besides, it must be taken into account that there is also commercial open software, as well as free privative software. In any case, the excellence of the software may be independent of such variables. Thus, the best strategy is the coexistence and free competition of all kinds of software. This will allow a quality improvement and an innovation enhancement, which will benefit the education, research, management and assistance at the university in particular and at the whole society in general.El software público libre es el fundamento del movimiento de software de fuente abierta (OSS). Éste puede facilitar el uso de estándares abiertos, con accesibilidad independiente de plataforma informática. El bajo coste o gratuidad de muchos productos OSS permite su implantación cuando los recursos económicos son escasos (países en desarrollo, escuelas, etc.). Además, su código se puede modificar, adaptar y mejorar por cualquiera, ya que es público. No obstante, el OSS también puede presentar inconvenientes. Así, su desarrollo puede no ser tan ordenado y jerárquico como el del software privativo y puede no tener una financiación apropiada. De este modo, puede verse comprometida la facilidad de uso y coherencia del producto final. Ello puede incrementar los costes de transición, entrenamiento y soporte técnico. Por otra parte, conviene recordar que existe software libre comercial y software privativo gratuito. En cualquier caso, la excelencia del software puede ser independiente de dichas variables. Por tanto, la mejor estrategia es la coexistencia y libre competencia de todo tipo de software. Así se puede conseguir una mejora de calidad y una potenciación de la innovación, que beneficie a la docencia, investigación, gestión y asistencia universitarias en particular, así como a la sociedad en general

    Transition period between vegetation growth and senescence controls interannual variability of C fluxes in a Mediterranean reed wetland

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    Wetlands are crucial ecosystems modulating climate change due to their great potential to capture carbon dioxide (CO2), emit methane (CH4) and regulate local climate through evapotranspiration (ET). Common reed wetlands are particularly interesting given their high productivity, abundance and highly efficient internal gas-transport mechanism. However, little is known about the interannual behavior and dominant controlling factors of Mediterranean reed wetlands, characterized by seasonal flooding and remarkable weather variability. After 6 years of ecosystem carbon and ET flux measurements by eddy covariance (3 years for CH4 fluxes), this study shows the functional vulnerability of such wetlands to climate variability, switching between carbon (CO2+CH4) sink (660 g CO2-eeq m-2 y -1 , in 2014) and source (360 g CO2-eq m-2 y -1 , in 2016) in short periods of time. According to our analyses, the great interannual variability appeared to mainly depend on the behavior of reed growth dynamics during the transition to senescence period, what is confirmed through the Enhanced Vegetation Index as a proxy of photosynthetic activity. Additionally, a similar behavior of seasonal and daily patterns of carbon fluxes and ET was found compared with other wetlands under different climates
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