1,140 research outputs found

    Somatic embryogenesis in explants of adult wild olive trees

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    In this investigation, somatic embryogenesis in explants of adult wild olive trees, using the protocol developed by Mazri et al. (2013, Sci. Hort. 159: 88-95), was induced. Four genotypes differring in the level of resistance to the fungal pathogen Verticillium dahliae were used: Ac18, StopVert and OutVert (symptomless resistant genotypes, Jiménez-Fernández et al. 2015, Plant Pathology, in press) and Ac15 (susceptible genotype, Jiménez-Díaz, IAS-CSIC, Córdoba, personal communication). Three types of explants from actively growing cultures were used: first pair of leaves, petioles and shoot apex. Firstly, all explants were cultured on a liquid induction medium with MS mineral elements at 0.5X and 30 μM TDZ-0.5 μM NAA, for 4 days at 80rpm. Afterwards, explants were transferred to basal MS with 0.5X macroelements, for 8 weeks. Finally, calli were cultured on expression ECO medium supplemented with 0.25 μM IBA, 0.5 μM 2ip and 0.44 μM BA, for several subcultures. Cultures were incubated under darkness at 25 degrees. Embryogenic calli were observed on shoot apex (StopVert) or leaf primordia (Ac18) explants.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Distributed Energy Resources Parameter Monitoring in Microgrids Using Blockchain and Edge Computing

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    An increased share of distributed renewable energy sources requires flexible tools for providing reliable and cheap electricity. Smart meters provide information at the consumer level, which could be used as the main source for real-time energy micro-transactions, however, one of the main concerns about direct transactions is information security. Conventional electricity markets rely on centralized information exchange, nevertheless, when intra-day, distributed, electricity consumption and production exchanges are required between customers, this approach might not be enough. This paper presents a proof-of-concept for using Blockchain as a tool for managing the operational transactions in a DC microgrid. The distributed nature of this technology provides an inherently safer approach, by providing an immutable database for transaction history. One of the challenges of using this technology, however, is the required computing power at the nodes and the limited capacity available in the smart meter. To overcome these issues, the authors used a distributed computing technology,-edge computing-, where computation and storage are located closer to the customer, to improve response times by handling the required computational tasks of the Blockchain tool. This approach proved not only to be practically viable but also, offers important insights about the scalability and capabilities of the technology. © 2020 IEEE

    NiO/CaAl2O4 as active oxygen carrier for low temperature chemical looping applications

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    The implementation of CO2 capture systems in conventional processes has been proposed by the IPCC as an effective way to reduce anthropogenic CO2 emissions. However, these capture systems may represent an important decrease in the global efficiency for conventional processes. Chemical Looping has already been demonstrated as a promising technology for more efficient CO2 capture. Novel reactor concepts have been proposed in the literature, in which the reactions take place at lower temperatures with increased overall energy efficiency. However, few investigations have been carried out regarding the behaviour of oxygen carriers at relatively low operating temperatures. In this work, an active Ni-based oxygen carrier supported on CaAl2O4 inert material has been tested and characterized. The oxygen carrier has shown a promising behaviour for low temperature applications. However, it has been demonstrated that the oxygen carrier has to be pre-treated because of an interesting activation process which takes place only at high reduction temperatures. Oxygen carrier activation is caused by a reorganization of superficial nickel. Fresh oxygen carrier is covered by a layer of nickel with a strong interaction with the support. However, once the sample is reduced at high temperatures Ni is reorganized into small grains with reduced interaction with the support. This results in an enhancement in the reactivity and a higher oxygen transport capacity. After about 200 redox cycles, a small decrease in the solid conversion is observed due to agglomeration of the NiO grains. Nevertheless, the redox kinetics is still sufficiently fast for low temperature applications, provided that the oxygen carrier is pre-activated. The kinetics rates for the gas–solid reactions and gas-phase catalytic reactions have been determined, which can be used to predict the performance of the activated NiO/CaAl2O4 oxygen carrier for low temperature chemical looping applications

    Deterioration modeling of sewer pipes via discrete-time Markov chains: A large-scale case study in the Netherlands

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    [For the latest version of this repository go to: https://gitlab.utwente.nl/fmt/degradation-models/dtmc_sewer_pipes.git] Sewer pipe network systems are an important part of civil infrastructure, and in order to find a good trade-off between maintenance costs and system performance, reliable sewer pipe degradation models are essential. In this paper, we present a large-scale case study in the city of Breda in the Netherlands. Our dataset has information on sewer pipes built since the 1920s and contains information on different covariates. We also have several types of damage, but we focus our attention on infiltrations, surface damage, and cracks. Each damage has an associated severity index ranging from 1 to 5. To account for the characteristics of sewer pipes, we defined 6 cohorts of interest. Two types of discrete-time Markov chains (DTMC), which we called Chain `Multi' and `Single' (where Chain `Multi'contains additional transitions compared to Chain `Single'), are commonly used to model sewer pipe degradation at the pipeline level, and we want to evaluate which suits better our case study. To calibrate the DTMCs, we define an optimization process using Sequential Least-Squares Programming to find the DTMC parameter that best minimizes the root mean weighted square error. Our results show that for our case study there is no substantial difference between Chain `Multi' and `Single', but the latter has fewer parameters and can be easily trained. Our DTMCs are useful to compare the cohorts via the expected values, e.g., concrete pipes carrying mixed and waste content reach severe levels of surface damage more quickly compared to concrete pipes carrying rainwater, which is a phenomenon typically identified in practice.This research has been partially funded by NWO under the grant PrimaVera (https://primavera-project.com) number NWA.1160.18.238, and has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 101008233

    Milk production of lacaune sheep with different degrees of crossing with manchega sheep in a commercial flock in Spain

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    The objective of the present study was to evaluate the effect of the grade of crossbreeding (Lacaune x Manchega) and environmental factors on milk production in a commercial flock in Spain. A total of 5769 milk production records of sheep with different degrees of purity of the Lacaune breed crossed with Manchega were used as follows: 100% Lacaune (n = 2960), 7/8 Lacaune (n = 502), 13/16 Lacaune (n = 306), 3/4 (n = 1288), 5/8 Lacaune (n = 441) and 1/2 Lacaune: Manchega (n = 272). Additional available information included the number of parity (1 to 8), litter size (single or multiple), and the season of the year of lambing (spring, summer, autumn and winter). A mixed model was used to evaluate the level of crossbreeding and environmental factors on milk production. The 100% Lacaune sheep presented the highest milk production with respect to the F1 Lacaune x Manchega sheep (p < 0.01), showing that as the degree of gene absorption increases with the Manchega breed, it presents lower milk yield. The 100%, 13/16, and 3/4 Lacaune genotypes had the highest milk yields with respect to the 1/2 Lacaune/Manchega breed (p < 0.001). The Lacaune registered on average 181.1 L in a period adjusted to 160 days of lactation (1.13 L/ day). Likewise, the parity number, litter size, and season of lambing effects showed significant differences (p < 0.01). It was concluded that 13/16 and 3/4 Lacaune/Manchega ewes presented the highest milk yields with respect to the other crosses

    Cosmic Chronometers: Constraining the Equation of State of Dark Energy. I: H(z) Measurements

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    We present new determinations of the cosmic expansion history from red-envelope galaxies. We have obtained for this purpose high-quality spectra with the Keck-LRIS spectrograph of red-envelope galaxies in 24 galaxy clusters in the redshift range 0.2 < z < 1.0. We complement these Keck spectra with high-quality, publicly available archival spectra from the SPICES and VVDS surveys. We improve over our previous expansion history measurements in Simon et al. (2005) by providing two new determinations of the expansion history: H(z) = 97 +- 62 km/sec/Mpc at z = 0.5 and H(z) = 90 +- 40 km/sec/Mpc at z = 0.8. We discuss the uncertainty in the expansion history determination that arises from uncertainties in the synthetic stellar-population models. We then use these new measurements in concert with cosmic-microwave-background (CMB) measurements to constrain cosmological parameters, with a special emphasis on dark-energy parameters and constraints to the curvature. In particular, we demonstrate the usefulness of direct H(z) measurements by constraining the dark- energy equation of state parameterized by w0 and wa and allowing for arbitrary curvature. Further, we also constrain, using only CMB and H(z) data, the number of relativistic degrees of freedom to be 4 +- 0.5 and their total mass to be < 0.2 eV, both at 1-sigma.Comment: Submitted to JCA
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