126 research outputs found

    Assessing the impact of LAI data assimilation on simulations of the soil water balance and maize development using MOHID-Land

    Get PDF
    Hydrological modeling at the catchment scale requires the upscaling of many input parameters for better characterizing landscape heterogeneity, including soil, land use and climate variability. In this sense, remote sensing is often considered as a practical solution. This study aimed to access the impact of assimilation of leaf area index (LAI) data derived from Landsat 8 imagery on MOHID-Land’s simulations of the soil water balance and maize state variables (LAI, canopy height, aboveground dry biomass and yield). Data assimilation impacts on final model results were first assessed by comparing distinct modeling approaches to measured data. Then, the uncertainty related to assimilated LAI values was quantified on final model results using a Monte Carlo method. While LAI assimilation improved MOHID-Land’s estimates of the soil water balance and simulations of crop state variables during early stages, it was never sufficient to overcome the absence of a local calibrated crop dataset. Final model estimates further showed great uncertainty for LAI assimilated values during earlier crop stages, decreasing then with season reaching its end. Thus, while model simulations can be improved using LAI data assimilation, additional data sources should be considered for complementing crop parameterizationinfo:eu-repo/semantics/publishedVersio

    Modeling soil water dynamics and pasture growth in the montado ecosystem using MOHID land

    Get PDF
    The southern Iberian Peninsula is characterized by evergreen oak woodlands (locally known as montado), which constitute an important savanna-type agro-silvo-pastoral ecosystem. This ecosystem is facing a progressive decline for several reasons, with the foremost being overgrazing. Better management tools are necessary to accurately quantify the systems’ carrying capacity and the sustainable stocking rates that prevent land degradation. The purpose of this study was to determine whether the MOHID-Land model could adequately simulate soil water dynamics and pasture growth in the montado ecosystem. The study area was located in the Alentejo region of southern Portugal. The model successfully simulated soil water contents and aboveground biomass during the 2010–2011 and 2011–2012 growing seasons, producing acceptable errors of the estimates (0.015 RMSE 0.026 cm3 cm3; 279 RMSE 1286.5 kg ha1), and relatively high modeling efficiencies (0.481 EF 0.882). The model was further used to simulate the same variables for a longer period (1979/2009 seasons), to account for the effect of climate variability on model estimates. Water balance and dry biomass estimates were found to be significantly different between rainfed and irrigated pastures, as well as between the ten driest and ten wettest seasons, with the model responding well to climate variability. The results showed the potential of using the MOHID-Land model for improving pasture management in the montado ecosysteminfo:eu-repo/semantics/publishedVersio

    Release of acyclovir from polymeric nanofibers: comparing aqueous versus membrane-water interfaces kinetics

    Get PDF
    We are very thankful to Labesfal Genericos, S.A. for kindly providing acyclovir. We also thank PARALAB for the SEM-EDS analysis and Sr. Azevedo for the X-ray analysis. This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2013. Marlene LĂșcio acknowledges the exploratory project funded by FCT with the reference IF/00498/2012The objective of this study is to develop a novel system for acyclovir (ACV) controlled release after cutaneous application through the encapsulation of the drug into polymeric nanofibers of policaprolactone (PCL) produced by the electrospinning technique to overcome the limitations of the conventional topical formulations.info:eu-repo/semantics/publishedVersio

    Fucoidan immobilized at the surface of a fibrous mesh presents toxic effects over melanoma cells, but not over non-cancer skin cells

    Get PDF
    The use of fucoidan, a marine-origin bioactive polymer, is herein proposed as a component of an innovative and effective strategy against melanoma, one of the most aggressive skin cancers. First, fucoidan antitumor activity, in its soluble form, was assessed presenting increased cytotoxicity over melanoma cells when compared to human dermal fibroblasts and keratinocytes. After this antitumor activity validation and trying to develop a more targeted and local strategy aiming to diminish the cytotoxic effects over noncancer cells, fucoidan was immobilized at the surface of an electrospun nanofiber mesh (NFM_Fu), envisioning the development of a therapeutic patch. The maximum immobilization concentration was 1.2 mg mLĂą 1, determined by the Toluidine Blue Assay and confirmed by XPS. Furthermore, NFM_Fu is more hydrophilic than NFM, presenting a contact angle of 36°, lower than the 121° of the control condition. NFM_Fu was able to reduce human melanoma cell viability by 50% without affecting human dermal fibroblasts and keratinocytes. Taken together, these results set the basis for a valuable approach for melanoma treatment.This work was developed under the scope of the Structured Projects for R&D&I NORTE-01-0145-FEDER-000021 and NORTE-01-0145-FEDER-000023 supported by the Northern Portugal Regional Operational Programme (NORTE 2020),under the Portugal 2020 Partnership Agreement. The authors would like also to thank NORTE 2020 for financing the Ph.D.scholarship of C.O.“Norte-08-5369-000037”and the Portuguese Foundation for Science and Technology for the Investigator Grant of A.M. (IF/00376/2014). Dr. Luísa Rodrigues is acknowledged by the XPS analysis

    Control release of acyclovir nanocristals from electrospun nanofibers: comparison of two polymeric matrices

    Get PDF
    The objective of this study is to develop a novel system for cutaneous application of ACV that is capable of a controlled release of the drug overcoming the limitations of the conventional topical formulations.We are thankful to Labesfal Genericos, S.A. for kindly providing acyclovir. We also thank PARALAB for the SEM-EDS analysis and Dr. A. S. Azevedo for the X-ray analysis. This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2013. Marlene LĂșcio acknowledges the exploratory project funded by FCT with the reference IF/00498/2012.info:eu-repo/semantics/publishedVersio

    Uncovering archaeological sites in airborne LiDAR data with data-centric artificial intelligence

    Get PDF
    Mapping potential archaeological sites using remote sensing and artificial intelligence can be an efficient tool to assist archaeologists during project planning and fieldwork. This paper explores the use of airborne LiDAR data and data-centric artificial intelligence for identifying potential burial mounds. The challenge of exploring the landscape and mapping new archaeological sites, coupled with the difficulty of identifying them through visual analysis of remote sensing data, results in the recurring issue of insufficient annotations. Additionally, the top-down nature of LiDAR data hinders artificial intelligence in its search, as the morphology of archaeological sites blends with the morphology of natural and artificial shapes, leading to a frequent occurrence of false positives. To address this problem, a novel data-centric artificial intelligence approach is proposed, exploring the available data and tools. The LiDAR data is pre-processed into a dataset of 2D digital elevation images, and the known burial mounds are annotated. This dataset is augmented with a copy-paste object embedding based on Location-Based Ranking. This technique uses the Land-Use and Occupation Charter to segment the regions of interest, where burial mounds can be pasted. YOLOv5 is trained on the resulting dataset to propose new burial mounds. These proposals go through a post-processing step, directly using the 3D data acquired by the LiDAR to verify if its 3D shape is similar to the annotated sites. This approach drastically reduced false positives, attaining a 72.53% positive rate, relevant for the ground-truthing phase where archaeologists visit the coordinates of proposed burial mounds to confirm their existence.This work was supported by the Project Odyssey: Platform for Automated Sensing in Archaeology Co-Financed by COMPETE 2020 and Regional Operational Program Lisboa 2020 through Portugal 2020 and FEDER under Grant ALG-01-0247-FEDER-070150.info:eu-repo/semantics/publishedVersio

    The African hind's (Cephalopholis taeniops, serranidae) use of artificial reefs off Sal Island (Cape Verde): a preliminary study based on acoustic telemetry

    Get PDF
    The African hind Cephalopholis taeniops (Valenciennes, 1828) is one of the most important commercial demersal species caught in the Cape Verde archipelago. The species is closely associated with hard substrate and is one of the main attractions for SCUBA divers. In January 2006 a former Soviet fishing vessel - the Kwarcit - was sunk off Santa Maria Bay (Sal Island). Young C. taeniops are commonly observed in this artificial reef (AR). In order to investigate the species' use of the AR, 4 specimens were captured and surgically implanted underwater with Vemco brand acoustic transmitters. The fish were monitored daily with an active telemetry receiver for one week after release. Simultaneously, an array of 3 passive VR2 / VR2W receivers was set for 63 days, registering data that allowed an analysis of spatial, daily and short term temporal activity patterns. The results showed site fidelity to the AR, with no migrations to the nearby natural reef. The method used allowed to register a consistent higher activity during daytime and a preference for the area opposite the dominant current

    How density functional theory surface energies may explain the morphology of particles, nanosheets, and conversion films based on layered double hydroxides

    Get PDF
    Conversion films based on layered double hydroxides constitute an important and environmentally friendly technology for the corrosion protection of aeronautical structures. Unfortunately, the morphology of layered double hydroxide (LDH) conversion films is still not well understood. In the present work, the structure and driving forces behind the morphology of zinc−aluminum LDH conversion films on aluminum alloy 2024 (AA2024) are explained from the perspective of molecular modeling. Since LDH particles are the core structures of LDH conversion films, the first step in this work was to understand the relation between structure and morphology of the particles themselves and the single-layer nanosheets that constitute them. Results regarding LDH’s crystallites, particles, and conversion films obtained using X-ray diffraction (XRD), dynamic light scattering (DLS), scanning electron microscopy (SEM), and atomic force microscopy (AFM) are interpreted using periodic model density functional theory (DFT) calculations. On the basis of the understanding of the formation of LDH particles and their exfoliation to obtain single-layer nanosheets, for the first time, LDH conversion films have been modeled using periodic model DFT. The results point to a preferential orientation of the cationic layers perpendicular to the surface, thus explaining the film morphology (SEM and AFM) and providing a rational for their crystallization process.publishe

    Facts and distortions in an endogenous growth model with physical capital, human capital and varieties

    Get PDF
    This article studies a model with physical and human capital accumulation and varieties. The model includes several distortions: duplication effects, spillovers, creative destruction, surplus appropriability, and an erosion effect. We show that the duplication effect in R&D is essential to make the model replicate several stylized facts linked with R&D. We evaluate the distance to the optimal solution, comparing the strength of each distortion.info:eu-repo/semantics/publishedVersio

    Prototype of an affordable pressure-controlled emergency mechanical ventilator for COVID-19

    Full text link
    We present a viable prototype of a simple mechanical ventilator intended as a last resort to ventilate COVID-19 patients. The prototype implements the pressure-controlled continuous mandatory ventilation mode (PC-CMV) with settable breathing rates, inspiration/expiration time ratios and FiO2 modulation. Although safe, the design aims to minimize the use of technical components and those used are common in industry, so its construction may be possible in times of logistical shortage or disruption or in areas with reduced access to technical materials and at a moderate cost, affordable to lower income countries. Most of the device can be manufactured by modest technical means and construction plans are provided.Comment: This version differs from version 2 in that it includes toxicological and bio-safety tests and updated electronic
    • 

    corecore