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Search: WFRF:(Holstein N.)

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1.
  • Rieth, M., et al. (author)
  • Review on the EFDA programme on tungsten materials technology and science
  • 2011
  • In: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 417:1-3, s. 463-467
  • Journal article (peer-reviewed)abstract
    • All the recent DEMO design studies for helium cooled divertors utilize tungsten materials and alloys, mainly due to their high temperature strength, good thermal conductivity, low erosion, and comparably low activation under neutron irradiation. The long-term objective of the EFDA fusion materials programme is to develop structural as well as armor materials in combination with the necessary production and fabrication technologies for future divertor concepts. The programmatic roadmap is structured into four engineering research lines which comprise fabrication process development, structural material development, armor material optimization, and irradiation performance testing, which are complemented by a fundamental research programme on "Materials Science and Modeling". This paper presents the current research status of the EFDA experimental and testing investigations, and gives a detailed overview of the latest results on fabrication, joining, high heat flux testing, plasticity, modeling, and validation experiments.
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3.
  • Paton, A., et al. (author)
  • Plant and fungal collections: Current status, future perspectives
  • 2020
  • In: Plants People Planet. - : Wiley. - 2572-2611. ; 2:5, s. 499-514
  • Journal article (peer-reviewed)abstract
    • Societal Impact Statement Plant and fungal specimens provide the auditable evidence that a particular organism occurred at a particular place, and at a particular point in time, verifying past occurrence and distribution. They also document the aspects of human exploration and culture. Collectively specimens form a global asset with significant potential for new uses to help address societal and environmental challenges. Collections also serve as a platform to engage and educate a broad range of stakeholders from the academic to the public, strengthening engagement and understanding of plant and fungal diversity-the basis of life on Earth. SummaryWe provide a global review of the current state of plant and fungal collections including herbaria and fungaria, botanic gardens, fungal culture collections, and biobanks. The review focuses on the numbers of collections, major taxonomic group and species level coverage, geographical representation and the extent to which the data from collections are digitally accessible. We identify the major gaps in these collections and in digital data. We also consider what collection types need to be further developed to support research, such as environmental DNA and cryopreservation of desiccation-sensitive seeds. Around 31% of vascular plant species are represented in botanic gardens, and 17% of known fungal species are held in culture collections, both these living collections showing a bias toward northern temperate taxa. Only 21% of preserved collections are available via the Global Biodiversity Information Facility (GBIF) with Asia, central and north Africa and Amazonia being relatively under-represented. Supporting long-term collection facilities in biodiverse areas should be considered by governmental and international aid agencies, in addition to short-term project funding. Institutions should consider how best to speed up digitization of collections and to disseminate all data via aggregators such as GBIF, which will greatly facilitate use, research, and community curation to improve quality. There needs to be greater alignment between biodiversity informatics initiatives and standards to allow more comprehensive analysis of collections data and to facilitate linkage of extended information, facilitating broader use. Much can be achieved with greater coordination through existing initiatives and strengthening relationships with users.
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4.
  • Rieth, M., et al. (author)
  • A brief summary of the progress on the EFDA tungsten materials program
  • 2013
  • In: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 442:1-3, s. S173-S180
  • Journal article (peer-reviewed)abstract
    • The long-term objective of the European Fusion Development Agreement (EFDA) fusion materials programme is to develop structural and armor materials in combination with the necessary production and fabrication technologies for reactor concepts beyond the International Thermonuclear Experimental Reactor. The programmatic roadmap is structured into four engineering research lines which comprise fabrication process development, structural material development, armor material optimization, and irradiation performance testing, which are complemented by a fundamental research programme on "Materials Science and Modeling." This paper presents the current research status of the EFDA experimental and testing investigations, and gives a detailed overview of the latest results on materials research, fabrication, joining, high heat flux testing, plasticity studies, modeling, and validation experiments.
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5.
  • Rieth, M., et al. (author)
  • Recent progress in research on tungsten materials for nuclear fusion applications in Europe
  • 2013
  • In: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 432:1-3, s. 482-500
  • Research review (peer-reviewed)abstract
    • The current magnetic confinement nuclear fusion power reactor concepts going beyond ITER are based on assumptions about the availability of materials with extreme mechanical, heat, and neutron load capacity. In Europe, the development of such structural and armour materials together with the necessary production, machining, and fabrication technologies is pursued within the EFDA long-term fusion materials programme. This paper reviews the progress of work within the programme in the area of tungsten and tungsten alloys. Results, conclusions, and future projections are summarized for each of the programme's main subtopics, which are: (1) fabrication, (2) structural W materials, (3) W armour materials, and (4) materials science and modelling. It gives a detailed overview of the latest results on materials research, fabrication processes, joining options, high heat flux testing, plasticity studies, modelling, and validation experiments.
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6.
  • Keppler, M., et al. (author)
  • Discovery of a planetary-mass companion within the gap of the transition disk around PDS 70
  • 2018
  • In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 617
  • Journal article (peer-reviewed)abstract
    • Context. Young circumstellar disks are the birthplaces of planets. Their study is of prime interest to understand the physical and chemical conditions under which planet formation takes place. Only very few detections of planet candidates within these disks exist, and most of them are currently suspected to be disk features.Aims. In this context, the transition disk around the young star PDS 70 is of particular interest, due to its large gap identified in previous observations, indicative of ongoing planet formation. We aim to search for the presence of an embedded young planet and search for disk structures that may be the result of disk-planet interactions and other evolutionary processes.Methods. We analyse new and archival near-infrared images of the transition disk PDS 70 obtained with the VLT/SPHERE, VLT/NaCo, and Gemini/NICI instruments in polarimetric differential imaging and angular differential imaging modes.Results. We detect a point source within the gap of the disk at about 195 mas (similar to 22 au) projected separation. The detection is confirmed at five different epochs, in three filter bands and using different instruments. The astrometry results in an object of bound nature, with high significance. The comparison of the measured magnitudes and colours to evolutionary tracks suggests that the detection is a companion of planetary mass. The luminosity of the detected object is consistent with that of an L-type dwarf, but its IR colours are redder, possibly indicating the presence of warm surrounding material. Further, we confirm the detection of a large gap of similar to 54 au in size within the disk in our scattered light images, and detect a signal from an inner disk component. We find that its spatial extent is very likely smaller than similar to 17 au in radius, and its position angle is consistent with that of the outer disk. The images of the outer disk show evidence of a complex azimuthal brightness distribution which is different at different wavelengths and may in part be explained by Rayleigh scattering from very small grains.Conclusions. The detection of a young protoplanet within the gap of the transition disk around PDS 70 opens the door to a so far observationally unexplored parameter space of planetary formation and evolution. Future observations of this system at different wavelengths and continuing astrometry will allow us to test theoretical predictions regarding planet-disk interactions, planetary atmospheres, and evolutionary models.
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7.
  • Olofsson, J., et al. (author)
  • Resolving faint structures in the debris disk around TWA 7 Tentative detections of an outer belt, a spiral arm, and a dusty cloud
  • 2018
  • In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 617
  • Journal article (peer-reviewed)abstract
    • Context. Debris disks are the intrinsic by-products of the star and planet formation processes. Most likely due to instrumental limitations and their natural faintness, little is known about debris disks around low mass stars, especially when it comes to spatially resolved observations. Aims. We present new VLT/SPHERE IRDIS dual-polarization imaging (DPI) observations in which we detect the dust ring around the M2 spectral type star TWA 7. Combined with additional angular differential imaging observations we aim at a fine characterization of the debris disk and setting constraints on the presence of low-mass planets. Methods. We modeled the SPHERE DPI observations and constrain the location of the small dust grains, as well as the spectral energy distribution of the debris disk, using the results inferred from the observations, and performed simple N-body simulations. Results. We find that the dust density distribution peaks at similar to 0.72 '' (25 au), with a very shallow outer power-law slope, and that the disk has an inclination of similar to 13 degrees with a position angle of similar to 91 degrees east of north. We also report low signal-to-noise ratio detections of an outer belt at a distance of similar to 1.5 '' (similar to 52 au) from the star, of a spiral arm in the southern side of the star, and of a possible dusty clump at 0.11 ''. These findings seem to persist over timescales of at least a year. Using the intensity images, we do not detect any planets in the close vicinity of the star, but the sensitivity reaches Jovian planet mass upper limits. We find that the SED is best reproduced with an inner disk at similar to 0.2 '' (similar to 7 au) and another belt at 0.72 '' (25 au). Conclusions. We report the detections of several unexpected features in the disk around TWA 7. A yet undetected 100 M-circle plus planet with a semi-major axis at 20-30 au could possibly explain the outer belt as well as the spiral arm. We conclude that stellar winds are unlikely to be responsible for the spiral arm.
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8.
  • Due, P., et al. (author)
  • Socioeconomic position, macroeconomic environment and overweight among adolescents in 35 countries
  • 2009
  • In: International Journal of Obesity. - : Springer Science and Business Media LLC. - 1476-5497 .- 0307-0565. ; 33:10, s. 1084-1093
  • Journal article (peer-reviewed)abstract
    • Objective: It is important to understand levels and social inequalities in childhood overweight within and between countries. This study examined prevalence and social inequality in adolescent overweight in 35 countries, and associations with macroeconomic factors. Design: International cross-sectional survey in national samples of schools. Subjects: A total of 11-, 13- and 15-year-olds from 35 countries in Europe and North America in 2001-2002 (N = 162 305). Measurements: The main outcome measure was overweight based on self-reported height and weight ( body mass index cut-points corresponding to body mass index of 25 kg/m(2) at the age of 18 years). Measures included family and school affluence (within countries), and average country income and economic inequality (between countries). Results: There were large variations in adolescent overweight, from 3.5% in Lithuanian girls to 31.7% in boys from Malta. Prevalence of overweight was higher among children from less affluent families in 21 of 24 Western and 5 of 10 Central European countries. However, children from more affluent families were at higher risk of overweight in Croatia, Estonia and Latvia. In Poland, Lithuania, Macedonia and Finland, girls from less affluent families were more overweight whereas the opposite was found for boys. Average country income was associated with prevalence and inequality in overweight when considering all countries together. However, economic inequality as measured by the Gini coefficient was differentially associated with prevalence and socioeconomic inequality in overweight among the 23-high income and 10-middle income countries, with a positive relationship among the high income countries and a negative association among the middle income countries. Conclusion: The direction and magnitude of social inequality in adolescent overweight shows large international variation, with negative social gradients in most countries, but positive social gradients, especially for boys, in some Central European countries. Macroeconomic factors are associated with the heterogeneity in prevalence and social inequality of adolescent overweight. International Journal of Obesity (2009) 33, 1084-1093; doi:10.1038/ijo.2009.128; published online 21 July 2009
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9.
  • Engler, N., et al. (author)
  • The high-albedo, low polarization disk around HD 114082 that harbors a Jupiter-sized transiting planet Constraints from VLT/SPHERE completed with TESS, Gaia, and radial velocities
  • 2023
  • In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 672
  • Journal article (peer-reviewed)abstract
    • Aims. We present new optical and near-infrared images of the debris disk around the F-type star HD 114082 in the Scorpius-Centaurus OB association. We obtained direct imaging observations and analyzed the TESS photometric time series data of this target with the goal of searching for planetary companions to HD 114082 and characterizing the morphology of the debris disk and the scattering properties of dust particles. Methods. HD 114082 was observed with the VLT/SPHERE instrument in different modes - the IRDIS camera in the K band (2.0-2.3 mu m) together with the IFS in the Y, J, and H bands (0.95-1.66 mu m) using the angular differential imaging technique as well as IRDIS in the H band (1.5-1.8 mu m) and ZIMPOL in the I_PRIME band (0.71-0.87 mu m) using the polarimetric differential imaging technique. To constrain the basic geometrical parameters of the disk and the scattering properties of dust grains, scattered light images were fitted with a 3D model for single scattering in an optically thin dust disk using a Markov chain Monte Carlo approach. We performed aperture photometry to derive the scattering and polarized phase functions, the polarization fraction, and the spectral scattering albedo for the dust particles in the disk. This method was also used to obtain the reflectance spectrum of the disk and, in turn, to retrieve the disk color and study the dust reflectivity in comparison to the debris disk HD 117214. We also performed the modeling of the HD 114082 light curve measured by TESS using models for planet transit and stellar activity to put constraints on the radius of the detected planet and its orbit. Last, we searched for additional planets in the system by combining archival radial velocity data, astrometry, and direct imaging. Results. The debris disk HD 114082 appears as an axisymmetric debris belt with a radius of similar to 0.37 '' (35 au), an inclination of similar to 83 degrees, and a wide inner cavity. Dust particles in HD 114082 have a maximum polarization fraction of similar to 17% and a higher reflectivity when compared to the debris disk HD 117214. This high reflectivity results in a spectral scattering albedo of similar to 0.65 for the HD 114082 disk at near-infrared wavelengths. The disk reflectance spectrum exhibits a red color at the position of the planetesimal belt and shows no obvious features, whereas that of HD 117214 might indicate the presence of CO2 ice. The analysis of TESS photometric data reveals a transiting planetary companion to HD 114082 with a radius of similar to 1 R-Jup on an orbit with a semimajor axis of 0.7 +/- 0.4 au. No additional planet was detected in the system when we combined the SPHERE images with constraints from astrometry and radial velocity. We reach deep sensitivity limits down to similar to 5 M-Jup at 50 au and similar to 10 M-Jup at 30 au from the central star.
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10.
  • Merlone, Andrea, et al. (author)
  • A new challenge for meteorological measurements : The meteoMet project-Metrology for meteorology
  • 2013
  • In: AIP Conference Proceedings. - : AIP. - 0094-243X .- 1551-7616. - 9780735411784 ; , s. 1030-1035
  • Conference paper (peer-reviewed)abstract
    • Climate change and its consequences require immediate actions in order to safeguard the environment and economy in Europe and in the rest of world. Aiming to enhance data reliability and reduce uncertainties in climate observations, a joint research project called MeteoMet-Metrology for Meteorology started in October 2011 coordinated by the Italian Istituto Nazionale di Ricerca Metrologica (INRiM). The project is focused on the traceability of measurements involved in climate change: surface and upper air measurements of temperature, pressure, humidity, wind speed and direction, solar irradiance and reciprocal influences between measurands. This project will provide the first definition at the European level of validated climate parameters with associated uncertainty budgets and novel criteria for interpretation of historical data series. The big challenge is the propagation of a metrological measurement perspective to meteorological observations. When such an approach will be adopted the requirement of reliable data and robust datasets over wide scales and long terms could be better met.
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