1,760 research outputs found

    Refining historical burned area data from satellite observations

    Get PDF
    • The burned area reported by global satellite products is largely biased. •We aimed to correct burned area biases before Sentinel-2 era. •A solution is to combine coarse resolution burned area with environmental data. •Validations in independent sites and years demonstrate that our tool is operational. Sentinel-2 imagery has revealed a substantial underestimation of burned area (BA) compared with earlier satellite products with coarser spatial resolution. In this context, we investigate the predictability of biases between the reference Sentinel-2 BA product developed for Sub-Saharan Africa (FireCCISFD) in 2019 and commonly used global coarse resolution BA products (MCD64, Fire CCI and C3S), providing tools to refine historical annual BA data before the Sentinel-2 era. To do so, we built a comprehensive dataset of environmental predictors of BA biases, with variables or proxies of (I) the annual BA estimated from the coarse-resolution product, (II) BA sizes, (III) the persistence and strength of BA signals, (IV) the maximum potential BA, and (V) the obstruction of land surface observation from satellites. Full and parsimonious random forest models were performed and validated through out-of-bag (OOB) estimations, and reconstructed BAs were validated with external data over space, and over time. The explained variance in BA biases was ≥78.58% (OOB) for all full and parsimonious models. The reconstructed BA data showed a high correspondence with the reference BA in the validation sites over space (≥91.15% var. explained) and time (≥90.37% var. explained), notably reducing biases of coarse resolution products. As an example of the model applicability, the spatial patterns of Madagascar’s BA were reconstructed for 2005, 2010, 2015 and 2020, revealing a burned extent between two and four times higher than previous estimations. The proposed models are operational solutions to obtain regional and global virtually unbiased BA estimates since 2000

    Organocatalytic strategies for the development of the enantioselective inverse-electron-demand hetero-Diels-Alder reaction

    Full text link
    Cycloaddition reactions, in particular Diels-Alder reactions, have attracted a lot of attention from organic chemists since they represent one of the most powerful methodologies for the construction of carbon-carbon bonds. In particular, inverse-electron-demand hetero-Diels-Alder reactions have been an important breakthrough for the synthesis of heterocyclic compounds. Among all their variants, the organocatalytic enantioselective version has been widely explored since the asymmetric construction of diversely functionalized scaffolds under reaction conditions encompassed within the green chemistry field is of great interest. In this review, a profound revision on the latest advances on the organocatalytic asymmetric inverse-electron demand hetero-Diels-Alder reaction is shownWe are grateful to the Spanish Government (CTQ2015-64561-R and RTI2018-095038-B-I00), “Comunidad de Madrid” and European Structural Funds (S2018/NMT-4367). J.A.F.-S. thanks the Spanish Government for a Ramón y Cajal contract. V.L.-M. thanks Universidad Autónoma de Madrid for a predoctoral fellowship (FPI-UAM

    Water-Covered Roof Versus Inverted Flat Roof on the Mediterranean Coast: A Comparative Study of Thermal and Energy Behavior

    Get PDF
    Reservoir, or water-collecting roofs present greater thermal inertia than inverted flat roofs due to the mass of water they contain. This feature gives them better thermal performance and leads to greater stability in the indoor air temperature Ti and the wall surface temperatures. In the summer, they can dampen the effect of solar radiation and regulate external thermal loads thanks to their greater effusivity and thermal capacity. This research compares the thermal behavior of the roofs of two buildings located in Alicante on the Spanish Mediterranean coast: a loft flat in the city center and a water-covered roof in the Museum of the University of Alicante (MUA). Values for effusivity, diffusivity, thermal capacity, decrement factor, time lag and internal, as well as external thermal admittance were obtained. After monitoring both roofs during 2014, behavior simulations were performed in Design Builder using 6 different scenarios reflecting different combinations in both buildings of water-covered, inverted and conventional roofs and marble or terrazzo paving. The water-covered roof led to a higher decrement factor and time lag, as well as to a reduction of annual energy demands between 8.86% and 9.03%.This research was funded by the Vice-rectorate of Campus and Technology of the University of Alicante, in grants awarded by the Own Programme in 2014

    Lighting up G protein-coupled purinergic receptors with engineered fluorescent ligands

    Get PDF
    The use of G protein-coupled receptors fluorescent ligands is undergoing continuous expansion. In line with this, fluorescent agonists and antagonists of high affinity for G protein-coupled adenosine and P2Y receptors have been shown to be useful pharmacological probe compounds. Fluorescent ligands for A1R, A2AR, and A3R (adenosine receptors) and P2Y2R, P2Y4R, P2Y6R, and P2Y14R (nucleotide receptors) have been reported. Such ligands have been successfully applied to drug discovery and to GPCR characterization by flow cytometry, fluorescence correlation spectroscopy, fluorescence microscopy, fluorescence polarization, fluorescence resonance energy transfer and scanning confocal microscopy. Here we summarize recently reported and readily available representative fluorescent ligands of purinergic receptors. In addition, we pay special attention on the use of this family of fluorescent ligands revealing two main aspects of purinergic receptor biology, namely ligand binding and receptor oligomerization

    SANS study of hybrid silica aerogels under "in situ" uniaxial compression

    Get PDF
    We have modified the inorganic silica network of aerogels with polydimethylsiloxane (PDMS), a hydroxyl-terminated polymer, to obtain an organic modified silicate (ORMOSIL). Reactions were assisted by high-power ultrasounds. The resulting gels were dried under supercritical conditions of the solvent to obtain a monolithic sono-aerogel. The mechanical behaviour of these aerogels can be tuned from brittle to rubbery as a function of the organic polymer content. In order to determine the links between the mechanical behaviour and modifications made to the microstructure, SANS (small-angle neutron scattering) experiments were carried out. To measure the intensities under "in situ" uniaxial compression of the aerogel, a specific sample-holder was built. Under uniaxial compression the 2D-diagrams were significantly anisotropic (butterfly pattern), indicating the rearrangement of the polymer. The form factor of these aerogels is described well by two correlation lengths, small microporous silica clusters surrounded by entangled polymer chains of 6 nm average size (blobs), which form a larger secondary level of agglomerates governed by the "frozen-in" elastic constraints.Comisión Interministerial de Ciencia y Tecnología MAT2005-1583European Commission CT-2003-50592

    Adenoma pleomorfo del septum nasal, dos casos clínicos y revisión del tema

    Get PDF
    Indexación: ScieloEl tumor benigno más frecuente de las glándulas salivales mayores es el adenoma pleomorfo. Además de las glándulas salivales mayores, también puede ocurrir en las glándulas salivales del paladar duro y blando. Raros casos se han reportado en la nasofaringe, orofaringe, hipofaringe y laringe. Adenomas pleomorfos intranasales son muy infrecuentes y pueden ser mal diagnosticados debido a que tienen mayor celularidad mioepitelial y poco estroma mixoide, en comparación con los que se localizan en otros lugares. Presentamos dos raros casos de adenomas pleomorfos del septum nasal y analizamos los hallazgos patológicos y el manejo clínico. Se revisa la literatura en relación al tema.The most common benign tumor of major salivary glands is the pleomorphic adenoma. In addition to the major salivary glands may also occur in the salivary glands of hard and soft palate. Rare cases have been reported in the nasopharynx, oropharynx, hypopharynx and larynx. Intranasal pleomorphic adenomas are very rare and can be misdiagnosed because they have greater myoepithelial cellularity and little myxoid stroma, compared with those located elsewhere. We report two rare cases of pleomorphic adenomas of the nasal septum and analyze the pathological findings and clinical management. We review the literature on the subject.http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-48162011000100010&nrm=is

    A critical-path based iterated local search for the green permutation flowshop problem

    Get PDF
    The permutation flowshop scheduling problem is a widely studied combinatorial optimization problem with several real-world applications. In this paper we address a green variant of the problem with controllable processing times and two objective functions: one related to the service level of the factory (makespan) and another one related to the total cost or the total energy/carbon consumption. For this problem we propose a novel Critical-Path based Iterated Local Search. This metaheuristic incorporates several theoretical results to accelerate the search of solutions in the intensification phase. The proposed algorithm has been compared on an extensive benchmark with the most promising algorithms in the literature. The computational results show the excellent performance of the proposal.Ministerio de Ciencia e Innovación PID2019-108756RB-I00Junta de Andalucía US-126451

    UTILIZACIÓN DEL ACRÍLICO DENTAL (metil metacrilato) COMO BARRA ESTABILIZADORA-CONECTORA PARA REDUCCIONES CERRADAS EN FRACTURAS DE TIBIA/PERONÉ O RADIO/CÚBITO EN CANINOS

    Get PDF
    El metil metacrilato (mmc) es una resina acrílica utilizada en moldes para fabricar prótesis dentales y puede cumplir la función de barra estabilizadora-conectora en la reducción de fracturas, permitiendo la colocación de clavos en planos múltiples. El presente trabajo tuvo como objetivo comprobar que el acrílico dental sirve como barra conectora en la fijación externa esquelética, y demostrar que es posible fijar las fracturas con un método poco traumático, alejado del foco fracturario, para evitar las complicaciones post operatorias de las técnicas tradicionales. Se realizó la reducción cerrada de fractura en 10 perros con edades entre 5 meses y 7 años que presentaron fracturas de los huesos tibia/ peroné y cúbito/radio. Los animales fueron intervenidos y se tomaron radiografías cada 16 días hasta la extracción de la fijación externa a las 6 semanas postcirugía. Se logró el recubrimiento de la línea de fractura y una adecuada osteosíntesis que permitió un callo oseo adecuado, logrando una buena alineación del hueso.The methyl metracrilate (mmc) is an acrylic resin used in molds for the manufacture of dental prothesis and may have the function of connective stabilizing bar in the reduction of bone fractures, allowing the insertion of pins in diffent planes. The objective of the present research was to demonstrate that the mmc may work like a external skeletal locking device to fix bone fractures, away from the fracture focus, and therefore, avoiding much of the usual complications observed when other techniques are used. A closed fracture reduction was performed in 10 dogs, with ages varying froms 5 months and 7 years that presented a fracture in the tibia, the fibula, the ulna or the radius bones. All animals were intervened and X rayed every 16 days until the extraction of the external fixation was done on the 6th week post surgery. The recovery of the fracture line was obtained as well as an adequate osteosynthesis that allowed the bone recuperation
    corecore