24 research outputs found

    Retrieval of optical and microphysical properties of transported Saharan dust over Athens and Granada based on multi-wavelength Raman lidar measurements: Study of the mixing processes

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    In this paper we extract the aerosol microphysical properties for a collection of mineral dust cases measured by multi-wavelength depolarization Raman lidar systems located at the National Technical University of Athens (NTUA, Athens, Greece) and the Andalusian Institute for Earth System Research (IISTA-CEAMA, Granada, Spain). The lidar-based retrievals were carried out with the Spheroidal Inversion eXperiments software tool (SphInX) developed at the University of Potsdam (Germany). The software uses regularized inversion of a two-dimensional enhancement of the Mie model based on the spheroid-particle approximation with the aspect ratio determining the particle shape. The selection of the cases was based on the transport time from the source regions to the measuring sites. The aerosol optical depth as measured by AERONET ranged from 0.27 to 0.54 (at 500 nm) depending on the intensity of each event. Our analysis showed the hourly mean particle linear depolarization ratio and particle lidar ratio values at 532 nm ranging from 11 to 34% and from 42 to 79 sr respectively, depending on the mixing status, the corresponding air mass pathways and their transport time. Cases with shorter transport time showed good agreement in terms of the optical and SphInX-retrieved microphysical properties between Athens and Granada providing a complex refractive index value equal to 1.4 + 0.004i. On the other hand, the results for cases with higher transport time deviated from the aforementioned ones as well as from each other, providing, in particular, an imaginary part of the refractive index ranging from 0.002 to 0.005. Reconstructions of two-dimensional shape-size distributions for each selected layer showed that the dominant effective particle shape was prolate with diverse spherical contributions. The retrieved volume concentrations reflect overall the intensity of the episodes.Spanish Ministry of Sciences, Innovation and Universities through project CGL2016-81092,Spanish Ministry of Education, Culture and Sports through grant FPU14/0368

    Protection of 100kWp photovoltaic system against atmospheric overvoltages: A case study

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    Photovoltaic (PV) systems, due to their installation position, are exposed to direct and indirect lightning hits, which can damage the equipment of the system, resulting in interruption of the power supply, repair or/and replacement costs and dangers for the personnel. So, the implementation of an effective lightning protection system is a critical issue, in order to achieve safe and uninterrupted operation of photovoltaic installations. In the current work, the developed lightning surges in a 100kWp PV system are computed, by using appropriate computer tool; a sensitivity analysis is carried out in order to examine the impact of the soil resistivity, the lightning strike position and the connection of the grounding systems with the metallic frame of the PV on the arising surges. © 2016 IEEE

    Energy conservation strategies for sports centers: Part A. Sports halls

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    This paper summarizes the results from a number of energy audits and the analysis performed in order to improve indoor conditions and optimize energy use, in Hellenic sports halls, performed for the European Commission, in the framework of the SAVE program. The aim of this work was to investigate the technical, functional and administrative obstacles for energy conservation in sports centers (including swimming pools) and to propose practical and cost-effective solutions for improving their energy efficiency, indoor thermal and visual comfort throughout the year. The work concentrated on retrofitting of existing buildings, although the proposed design and management principles could also be followed in new projects in the area of sports and recreation facilities. © 1998 Elsevier Science S.A

    Energy conservation strategies for sports centers: Part B. Swimming pools

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    This paper summarizes the results from a number of energy audits and the analysis performed in order to improve indoor conditions and optimize energy use, in Hellenic indoor swimming pools, performed for the European Commission, in the framework of the SAVE program. The aim of this work was to investigate the technical, functional and administrative obstacles for energy conservation in sports centers (including sports halls) and to propose practical and cost-effective solutions for improving their energy efficiency, indoor thermal and visual comfort throughout the year. The work concentrated on retrofitting of existing buildings, although the proposed design and management principles could also be followed in new projects in the area of sports and recreation facilities. © 1998 Elsevier Science S.A

    Towards Elucidating Carnosic Acid Biosynthesis in Lamiaceae: Funtional Characterization of the Three First Steps of the Pathway in Slavia Fruicosa and Rosmarinus officinalis

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    Carnosic acid (CA) is a phenolic diterpene with anti-tumour, anti-diabetic, antibacterial and neuroprotective properties that is produced by a number of species from several genera of the Lamiaceae family, including Salvia fruticosa (Cretan sage) and Rosmarinus officinalis (Rosemary). To elucidate CA biosynthesis, glandular trichome transcriptome data of S. fruticosa were mined for terpene synthase genes. Two putative diterpene synthase genes, namely SfCPSand SfKSL, showing similarities to copalyl diphosphate synthase and kaurene synthase-like genes, respectively, were isolated and functionally characterized. Recombinant expression in Escherichia coli followed by in vitro enzyme activity assays confirmed that SfCPS is a copalyl diphosphate synthase. Coupling of SfCPS with SfKSL,both in vitro and in yeast, resulted in the synthesis miltiradiene, as confirmed by 1D and 2D NMR analyses (1H, 13C, DEPT, COSY H-H, HMQC and HMBC). Coupled transient in vivo assays of SfCPS and SfKSL in Nicotiana benthamiana further confirmed production of miltiradiene in planta. To elucidate the subsequent biosynthetic step, RNA-Seq data of S.fruticosa and R. officinalis were searched for cytochrome P450 (CYP) encoding genes potentially involved in the synthesis of the first phenolic compound in the CA pathway, ferruginol. Three candidate genes were selected, SfFS, RoFS1 and RoFS2. Using yeast and N. benthamiana expression systems, all three where confirmed to be coding for ferruginol synthases, thus revealing the enzymatic activities responsible for the first three steps leading to CA in two Lamiaceae genera

    Genomic innovations, transcriptional plasticity and gene loss underlying the evolution and divergence of two highly polyphagous and invasive Helicoverpa pest species

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    Background: Helicoverpa armigera and Helicoverpa zea are major caterpillar pests of Old and New World agriculture, respectively. Both, particularly H. armigera, are extremely polyphagous, and H. armigera has developed resistance to many insecticides. Here we use comparative genomics, transcriptomics and resequencing to elucidate the genetic basis for their properties as pests. Results: We find that, prior to their divergence about 1.5 Mya, the H. armigera/H. zea lineage had accumulated up to more than 100 more members of specific detoxification and digestion gene families and more than 100 extra gustatory receptor genes, compared to other lepidopterans with narrower host ranges. The two genomes remain very similar in gene content and order, but H. armigera is more polymorphic overall, and H. zea has lost several detoxification genes, as well as about 50 gustatory receptor genes. It also lacks certain genes and alleles conferring insecticide resistance found in H. armigera. Non-synonymous sites in the expanded gene families above are rapidly diverging, both between paralogues and between orthologues in the two species. Whole genome transcriptomic analyses of H. armigera larvae show widely divergent responses to different host plants, including responses among many of the duplicated detoxification and digestion genes. Conclusions: The extreme polyphagy of the two heliothines is associated with extensive amplification and neofunctionalisation of genes involved in host finding and use, coupled with versatile transcriptional responses on different hosts. H. armigera's invasion of the Americas in recent years means that hybridisation could generate populations that are both locally adapted and insecticide resistant
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