129 research outputs found

    Recent progress in the quantitative validation of JOREK simulations of ELMs in JET

    Get PDF
    Future devices like JT-60SA, ITER and DEMO require quantitative predictions of pedestal density and temperature levels, as well as inter-ELM and ELM divertor heat fluxes, in order to improve global confinement capabilities while preventing divertor erosion/melting in the planning of future experiments. Such predictions can be obtained from dedicated pedestal models like EPED, and from non-linear MHD codes like JOREK, for which systematic validation against current experiments is necessary. In this paper, we show progress in the quantitative validation of the JOREK code using JET simulations. Results analyse the impact of diamagnetic terms on the dynamics and size of the ELMs, and evidence is provided that the onset of type-I ELMs is not governed by linear MHD stability alone, but that a nonlinear threshold could be responsible for large MHD events at the plasma edgeEURATOM 633053RCUK Energy Programme EP/I501045Plasma HEC Consortium EPSRC EP/L000237/

    An outflow in the Seyfert ESO 362-G18 revealed by Gemini-GMOS/IFU Observations

    Get PDF
    We present two-dimensional stellar and gaseous kinematics of the inner 0.7 ×\times 1.2 kpc2^{2} of the Seyfert galaxy ESO 362-G18, derived from optical spectra obtained with the GMOS/IFU on the Gemini South telescope at a spatial resolution of ≈\approx170 pc and spectral resolution of 36 km s−1^{-1}. ESO 362-G18 is a strongly perturbed galaxy of morphological type Sa or S0/a, with a minor merger approaching along the NE direction. Previous studies have shown that the [OIII] emission shows a fan-shaped extension of ≈\approx 10\arcsec\ to the SE. We detect the [OIII] doublet, [NII] and Hα{\alpha} emission lines throughout our field of view. The stellar kinematics is dominated by circular motions in the galaxy plane, with a kinematic position angle of ≈\approx137∘^{\circ}. The gas kinematics is also dominated by rotation, with kinematic position angles ranging from 122∘^{\circ} to 139∘^{\circ}. A double-Gaussian fit to the [OIII]λ\lambda5007 and Hα{\alpha} lines, which have the highest signal to noise ratios of the emission lines, reveal two kinematic components: (1) a component at lower radial velocities which we interpret as gas rotating in the galactic disk; and (2) a component with line of sight velocities 100-250 km s−1^{-1} higher than the systemic velocity, interpreted as originating in the outflowing gas within the AGN ionization cone. We estimate a mass outflow rate of 7.4 ×\times 10−2^{-2} M⊙_{\odot} yr−1^{-1} in the SE ionization cone (this rate doubles if we assume a biconical configuration), and a mass accretion rate on the supermassive black hole (SMBH) of 2.2 ×\times 10−2^{-2} M⊙_{\odot} yr−1^{-1}. The total ionized gas mass within ∌\sim84 pc of the nucleus is 3.3 ×\times 105^{5} M⊙_{\odot}; infall velocities of ∌\sim34 km s−1^{-1} in this gas would be required to feed both the outflow and SMBH accretion.Comment: 18 pages, 14 figure

    Desalination effects on macroalgae (part A): Laboratory-controlled experiments with Dictyota spp. from the Pacific Ocean and Mediterranean Sea

    Get PDF
    Desalination brines from direct seawater intake that get discharged to coastal areas may produce stress responses on benthic marine communities, mostly due to its excess salinity, and especially on sessile organisms; in this context, macroalgae have been understudied in desalination ecotoxicological investigations. In this study, we assessed the short- and long-term cellular tolerance responses in two brown species of the macroalgae genus Dictyota through controlled laboratory conditions. Dictyota kunthii was collected from the eastern Pacific Ocean (average salinity, ~34 psu), whereas Dictyota dichotoma was from the Mediterranean Sea (average salinity, ~37 psu). Each macroalgae species was exposed for up to 7 days to two conditions with increased salinity values: +2 and +7 psu above their natural average salinity. Photosynthetic parameters and oxidative stress measurements were determined. The results showed that, in both Dictyota species, high salinity values induced reduced photoinhibition (Fv/Fm) but increased the primary productivity (ETRmax) and light requirement (EkETR) especially after 7 days. Conversely, the photosynthetic efficiency (αETR) decreased in hypersalinity treatments in D. dichotoma, while there were no changes in D. kunthii. The reactive oxygen species hydrogen peroxide (H2O2) was greater at high salinity values at 3 days for D. dichotoma and after 7 days in D. kunthii, while lipid peroxidation decreases under hypersalinity with time in both species. Despite the evident H2O2 accumulation in both species against hypersalinity, it did not produce oxidative damage and important impairment in the photosynthetic apparatus. These results contribute to understanding the tolerance strategies at the cellular level of Dictyota spp., which may be considered as potential candidates for biomonitoring of desalination impacts in the field.We gratefully thank the financial support from ANID FONDECYT Postdoctoral fellowship #3180394, European Commission Marie SkƂodowska-Curie Actions #888415, and ANID INES I+D # INID210013. Financial support for mobility was granted from SEGIB Scholarship and FundaciĂłn Carolina of Spain to PM. We also thank TESPOST 04/19 PhD scholarship granted by Universidad de Playa Ancha to PM. The initiative was also funded by Universidad de Playa Ancha through the Concurso Regular de InvestigaciĂłn 2019 no. CEA 19-20

    Desalination effects on macroalgae (part b): Transplantation experiments at brine-impacted sites with Dictyota spp. from the Pacific Ocean and Mediterranean Sea

    Get PDF
    Desalination residual brines are mostly discharged to marine environments, which can produce osmotic stress on sensitive benthic organisms. In this investigation, we performed transplantation experiments nearby desalination plants using two brown macroalgae species from a cosmopolitan genus: Dictyota kunthii (Chile) and Dictyota dichotoma (Spain). Parameters related to photosynthetic activity and oxidative stress were evaluated at 3 and 7 days for D. kunthii, and 3 and 6 days for D. dichotoma; each at 2 different impacted sites and 1 control. We observed that brine exposition at both impacted sites in Chile generated a marked stress response on D. kunthii, reflected in a decrease of primary productivity (ETRmax), light requirement (EkETR), and an excessive thermal dissipation (NPQmax), especially at 7 days. In D. dichotoma, similar impaired photosynthetic activity was recorded but only at the highest brine influence site during day 3. Regarding oxidative stress, both species displayed high levels of H2O2 when exposed to brine-influenced sites. Although in D. kunthii H2O2 content together with lipid peroxidation was higher after 3 days, these returned to baseline values towards day 7; instead, D. dichotoma H2O2 levels increased only at day 6. This easy and practical approach has proven to provide valuable data to address potential impacts of brine discharges at global scale coastal ecosystems.We gratefully thank financial support to ANID FONDECYT Postdoctoral fellowship #3180394, European Commission Marie SkƂodowska-Curie Actions #888415, and ANID INES I+D # INID210013. Financial support for mobility granted from SEGIB Scholarship and Fundación Carolina of Spain to PM. Also, we thank TESPOST 04/19 PhD scholarship granted by Universidad de Playa Ancha to PM

    Assessment of the Requirements within the Environmental Monitoring Plans Used to Evaluate the Environmental Impacts of Desalination Plants in Chile

    Get PDF
    Seawater desalination represents an alternative solution to face the challenge of water scarcity in Chile. However, the uncertainty toward potential environmental impacts of desalination plants represent a barrier to achieving water sustainability and socioeconomic development in Chile. This study aimed to assess the quality of environmental monitoring plans (EMP) and determine the aspects to be improved within it, in order to enhance the management of desalination plants during the operation phase and guarantee a sustainable development of the activity. The Environmental Impact Assessments (EIAs) and Environmental Impact Studies for seawater desalination projects published in the Environmental Impact Evaluation System (SEIA) in Chile between 1997 and 2018 were reviewed. The results of the brine production from desalination plants showed a significant increase in the last decade (about 1.6 Mm3 per year estimated according to the projects approved or under implementation). The EMPs data show heterogeneity and increasing requirements over time, which can be attributed to the governmental effort to improve environmental protection. Furthermore, a high frequency of irrelevant descriptors was identified in the current EMPs. The study thus recommended standardizing the environmental requirements included in EMPs based on empiric scientific knowledge to enhance the environmental protection programs in Chile.I.S. has a grant funded by University of Alicante and Sacyr Agua S.L. Also, P.T.M. and C.A.S were funded by project CEA 01-1819 from Convenio Desempeño UPA 1795 granted to Universidad de Playa Ancha

    MAPK Pathway under Chronic Copper Excess in Green Macroalgae (Chlorophyta): Involvement in the Regulation of Detoxification Mechanisms

    Get PDF
    Following the physiological complementary/parallel Celis-Plå et al., by inhibiting extracellular signal regulated kinases (ERK), c-Jun N-terminal kinases (JNK), and cytokinin specific binding protein (p38), we assessed the role of the mitogen-activated protein kinases (MAPK) pathway in detoxification responses mediated by chronic copper (10 ”M) in U. compressa. Parameters were taken at 6, 24, and 48 h, and 6 days (d). H2O2 and lipid peroxidation under copper and inhibition of ERK, JNK, or p38 alone increased but recovered by the sixth day. By blocking two or more MAPKs under copper, H2O2 and lipid peroxidation decayed even below controls. Inhibition of more than one MAPK (at 6 d) caused a decrease in total glutathione (reduced glutathione (GSH) + oxidised glutathione (GSSG)) and ascorbate (reduced ascorbate (ASC) + dehydroascorbate (DHA)), although in the latter it did not occur when the whole MAPK was blocked. Catalase (CAT), superoxide dismutase (SOD), thioredoxin (TRX) ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), and glutathione synthase (GS), were downregulated when blocking more than one MAPK pathway. When one MAPK pathway was blocked under copper, a recovery and even enhancement of detoxification mechanisms was observed, likely due to crosstalk within the MAPKs and/or other signalling processes. In contrast, when more than one MAPK pathway were blocked under copper, impairment of detoxification defences occurred, demonstrating that MAPKs were key signalling mechanisms for detoxification in macroalgae.</jats:p

    MAPK Pathway under Chronic Copper Excess in Green Macroalgae (Chlorophyta): Influence on Metal Exclusion/Extrusion Mechanisms and Photosynthesis

    Get PDF
    There is currently no information regarding the role that whole mitogen activated protein kinase (MAPK) pathways play in counteracting environmental stress in photosynthetic organisms. To address this gap, we exposed Ulva compressa to chronic levels of copper (10 ”M) specific inhibitors of Extracellular Signal Regulated Kinases (ERK), c-Jun N-terminal Kinases (JNK), and Cytokinin Specific Binding Protein (p38) MAPKs alone or in combination. Intracellular copper accumulation and photosynthetic activity (in vivo chlorophyll a fluorescence) were measured after 6 h, 24 h, 48 h, and 6 days of exposure. By day 6, when one (except JNK) or more of the MAPK pathways were inhibited under copper stress, there was a decrease in copper accumulation compared with algae exposed to copper alone. When at least two MAPKs were blocked, there was a decrease in photosynthetic activity expressed in lower productivity (ETRmax), efficiency (αETR), and saturation of irradiance (EkETR), accompanied by higher non-photochemical quenching (NPQmax), compared to both the control and copper-only treatments. In terms of accumulation, once the MAPK pathways were partially or completely blocked under copper, there was crosstalk between these and other signaling mechanisms to enhance metal extrusion/exclusion from cells. Crosstalk occurred among MAPK pathways to maintain photosynthesis homeostasis, demonstrating the importance of the signaling pathways for physiological performance. This study is complemented by a parallel/complementary article Rodríguez-Rojas et al. on the role of MAPKs in copper-detoxification.</jats:p

    Towards a Synthetic Chloroplast

    Get PDF
    The evolution of eukaryotic cells is widely agreed to have proceeded through a series of endosymbiotic events between larger cells and proteobacteria or cyanobacteria, leading to the formation of mitochondria or chloroplasts, respectively. Engineered endosymbiotic relationships between different species of cells are a valuable tool for synthetic biology, where engineered pathways based on two species could take advantage of the unique abilities of each mutualistic partner.We explored the possibility of using the photosynthetic bacterium Synechococcus elongatus PCC 7942 as a platform for studying evolutionary dynamics and for designing two-species synthetic biological systems. We observed that the cyanobacteria were relatively harmless to eukaryotic host cells compared to Escherichia coli when injected into the embryos of zebrafish, Danio rerio, or taken up by mammalian macrophages. In addition, when engineered with invasin from Yersinia pestis and listeriolysin O from Listeria monocytogenes, S. elongatus was able to invade cultured mammalian cells and divide inside macrophages.Our results show that it is possible to engineer photosynthetic bacteria to invade the cytoplasm of mammalian cells for further engineering and applications in synthetic biology. Engineered invasive but non-pathogenic or immunogenic photosynthetic bacteria have great potential as synthetic biological devices

    NEK1 variants confer susceptibility to amyotrophic lateral sclerosis

    Get PDF
    To identify genetic factors contributing to amyotrophic lateral sclerosis (ALS), we conducted whole-exome analyses of 1,022 index familial ALS (FALS) cases and 7,315 controls. In a new screening strategy, we performed gene-burden analyses trained with established ALS genes and identified a significant association between loss-of-function (LOF) NEK1 variants and FALS risk. Independently, autozygosity mapping for an isolated community in the Netherlands identified a NEK1 p.Arg261His variant as a candidate risk factor. Replication analyses of sporadic ALS (SALS) cases and independent control cohorts confirmed significant disease association for both p.Arg261His (10,589 samples analyzed) and NEK1 LOF variants (3,362 samples analyzed). In total, we observed NEK1 risk variants in nearly 3% of ALS cases. NEK1 has been linked to several cellular functions, including cilia formation, DNA-damage response, microtubule stability, neuronal morphology and axonal polarity. Our results provide new and important insights into ALS etiopathogenesis and genetic etiology

    Overview of JET results for optimising ITER operation

    Get PDF
    The JET 2019–2020 scientific and technological programme exploited the results of years of concerted scientific and engineering work, including the ITER-like wall (ILW: Be wall and W divertor) installed in 2010, improved diagnostic capabilities now fully available, a major neutral beam injection upgrade providing record power in 2019–2020, and tested the technical and procedural preparation for safe operation with tritium. Research along three complementary axes yielded a wealth of new results. Firstly, the JET plasma programme delivered scenarios suitable for high fusion power and alpha particle (α) physics in the coming D–T campaign (DTE2), with record sustained neutron rates, as well as plasmas for clarifying the impact of isotope mass on plasma core, edge and plasma-wall interactions, and for ITER pre-fusion power operation. The efficacy of the newly installed shattered pellet injector for mitigating disruption forces and runaway electrons was demonstrated. Secondly, research on the consequences of long-term exposure to JET-ILW plasma was completed, with emphasis on wall damage and fuel retention, and with analyses of wall materials and dust particles that will help validate assumptions and codes for design and operation of ITER and DEMO. Thirdly, the nuclear technology programme aiming to deliver maximum technological return from operations in D, T and D–T benefited from the highest D–D neutron yield in years, securing results for validating radiation transport and activation codes, and nuclear data for ITER
    • 

    corecore