1,075 research outputs found

    Combining VIVO and Google Scholar data as sources for CERIF linked data: a case in the agricultural domain

    Get PDF
    The needs of global science have fostered open access to the results and contextual information of research organizations at an international scale. This requires the use of standards or shared data models to exchange information preserving its semantics when transferred between systems. In that direction, standards as CERIF or projects as VIVO were developed to exchange or expose the scientific knowledge. Also, there are other sources of scientific information in the Web that are useful to complement institutional repositories and CRISes. The heterogeneity of data models behind each source in turn raises the need for mappings between them to ease interchange and aggregate information. In this paper, we present a tool that integrates three sources of research information and enables their aggregating and export into both VIVO and CERIF models. We present a case study in agriculture using OpenAGRIS, a bibliographic database linked to Web sources with more than 7 million records. Concretely, we describe the methods to combine Google Scholar data for the scholarly content indexed in OpenAGRIS and aggregating new information provided by the first one, using our tool. Finally the information is stored in a VIVO instance and then translated into CERIF using a conversion process mapping both data models. The case demonstrates the possibilities of mapping tools to aggregate and translate CRIS information

    Wide-Field Survey of Emission-line Stars in IC 1396

    Full text link
    We have made an extensive survey of emission-line stars in the IC 1396 HII region to investigate the low-mass population of pre-main sequence (PMS) stars. A total of 639 H-alpha emission-line stars were detected in an area of 4.2 deg^2 and their i'-photometry was measured. Their spatial distribution exhibits several aggregates near the elephant trunk globule (Rim A) and bright-rimmed clouds at the edge of the HII region (Rim B and SFO 37, 38, 39, 41), and near HD 206267, which is the main exciting star of the HII region. Based on the extinction estimated from the near-infrared (NIR) color-color diagram, we have selected pre-main sequence star candidates associated with IC 1396. The age and mass were derived from the extinction corrected color-magnitude diagram and theoretical pre-main sequence tracks. Most of our PMS candidates have ages of < 3 Myr and masses of 0.2-0.6 Mo. Although it appears that only a few stars were formed in the last 1 Myr in the east region of the exciting star, the age difference among subregions in our surveyed area is not clear from the statistical test. Our results may suggest that massive stars were born after the continuous formation of low-mass stars for 10 Myr. The birth of the exciting star could be the late stage of slow but contiguous star formation in the natal molecular cloud. It may have triggered to form many low-mass stars at the dense inhomogeneity in and around the HII region by a radiation-driven implosion.Comment: 48 pages, 12 figures, 5 tables, accepted for publication in A

    Spitzer IRS Spectroscopy of the 10 Myr-old EF Cha Debris Disk: Evidence for Phyllosilicate-Rich Dust in the Terrestrial Zone

    Get PDF
    We describe Spitzer IRS spectroscopic observations of the 10 Myr-old star, EF Cha. Compositional modeling of the spectra from 5 {\mu}m to 35 {\mu}m confirms that it is surrounded by a luminous debris disk with LD/L\star ~ 10-3, containing dust with temperatures between 225 K and 430 K characteristic of the terrestrial zone. The EF Cha spectrum shows evidence for many solid-state features, unlike most cold, low-luminosity debris disks but like some other 10-20 Myr-old luminous, warm debris disks (e.g. HD 113766A). The EF Cha debris disk is unusually rich in a species or combination of species whose emissivities resemble that of finely powdered, laboratory-measured phyllosilicate species (talc, saponite, and smectite), which are likely produced by aqueous alteration of primordial anhydrous rocky materials. The dust and, by inference, the parent bodies of the debris also contain abundant amorphous silicates and metal sulfides, and possibly water ice. The dust's total olivine to pyroxene ratio of ~ 2 also provides evidence of aqueous alteration. The large mass volume of grains with sizes comparable to or below the radiation blow-out limit implies that planetesimals may be colliding at a rate high enough to yield the emitting dust but not so high as to devolatize the planetesimals via impact processing. Because phyllosilicates are produced by the interactions between anhydrous rock and warm, reactive water, EF Cha's disk is a likely signpost for water delivery to the terrestrial zone of a young planetary system.Comment: 21 pages, 10 figures, accepted for publication in The Astrophysical Journa

    Integrating descriptions of knowledge management learning activities into large ontological structures: A case study

    Get PDF
    Ontologies have been recognized as a fundamental infrastructure for advanced approaches to Knowledge Management (KM) automation, and the conceptual foundations for them have been discussed in some previous reports. Nonetheless, such conceptual structures should be properly integrated into existing ontological bases, for the practical purpose of providing the required support for the development of intelligent applications. Such applications should ideally integrate KM concepts into a framework of commonsense knowledge with clear computational semantics. In this paper, such an integration work is illustrated through a concrete case study, using the large OpenCyc knowledge base. Concretely, the main elements of the Holsapple & Joshi KM ontology and some existing work on e-learning ontologies are explicitly linked to OpenCyc definitions, providing a framework for the development of functionalities that use the built-in reasoning services of OpenCyc in KM ctivities. The integration can be used as the point of departure for the engineering of KM-oriented systems that account for a shared understanding of the discipline and rely on public semantics provided by one of the largest open knowledge bases available

    Young stars in Epsilon Cha and their disks: disk evolution in sparse associations

    Full text link
    (abridge) The nearby young stellar association Epsilon Cha association has an estimated age of 3-5 Myr, making it an ideal laboratory to study the disk dissipation process and provide empirical constraints on the timescale of planet formation. We combine the available literature data with our Spitzer IRS spectroscopy and VLT/VISIR imaging data. The very low mass stars USNO-B120144.7 and 2MASS J12005517 show globally depleted spectral energy distributions pointing at strong dust settling. 2MASS J12014343 may have a disk with a very specific inclination where the central star is effectively screened by the cold outer parts of a flared disk but the 10 micron radiation of the warm inner disk can still reach us. We find the disks in sparse stellar associations are dissipated more slowly than those in denser (cluster) environments. We detect C_{2}H_{2} rovibrational band around 13.7 micron on the IRS spectrum of USNO-B120144.7. We find strong signatures of grain growth and crystallization in all Epsilon Cha members with 10 micron features detected in their IRS spectra. We combine the dust properties derived in the Epsilon Cha sample with those found using identical or similar methods in the MBM 12, Coronet cluster, Eta Cha associations, and in the cores to disks (c2d) legacy program. We find that disks around low-mass young stars show a negative radial gradient in the mass-averaged grain size and mass fraction of crystalline silicates. A positive correlation exists between the mass-averaged grain sizes of amorphous silicates and the accretion rates if the latter is above ~10^{-9} Msun/yr, possibly indicating that those disks are sufficiently turbulent to prevent grains of several microns in size to sink into the disk interior.Comment: 17 pages, 18 figures, 6 tables, language revised; accepted to A&

    Time-resolved photometry of the young dipper RX~J1604.3-2130A:Unveiling the structure and mass transport through the innermost disk

    Get PDF
    Context. RX J1604.3-2130A is a young, dipper-type, variable star in the Upper Scorpius association, suspected to have an inclined inner disk, with respect to its face-on outer disk. Aims. We aim to study the eclipses to constrain the inner disk properties. Methods. We used time-resolved photometry from the Rapid Eye Mount telescope and Kepler 2 data to study the multi-wavelength variability, and archival optical and infrared data to track accretion, rotation, and changes in disk structure. Results. The observations reveal details of the structure and matter transport through the inner disk. The eclipses show 5 d quasi-periodicity, with the phase drifting in time and some periods showing increased/decreased eclipse depth and frequency. Dips are consistent with extinction by slightly processed dust grains in an inclined, irregularly-shaped inner disk locked to the star through two relatively stable accretion structures. The grains are located near the dust sublimation radius (similar to 0.06 au) at the corotation radius, and can explain the shadows observed in the outer disk. The total mass (gas and dust) required to produce the eclipses and shadows is a few % of a Ceres mass. Such an amount of mass is accreted/replenished by accretion in days to weeks, which explains the variability from period to period. Spitzer and WISE infrared variability reveal variations in the dust content in the innermost disk on a timescale of a few years, which is consistent with small imbalances (compared to the stellar accretion rate) in the matter transport from the outer to the inner disk. A decrease in the accretion rate is observed at the times of less eclipsing variability and low mid-IR fluxes, confirming this picture. The v sin i = 16 km s(-1) confirms that the star cannot be aligned with the outer disk, but is likely close to equator-on and to be aligned with the inner disk. This anomalous orientation is a challenge for standard theories of protoplanetary disk formation.Science & Technology Facilities Council (STFC): ST/S000399/1. ESO fellowship. European Union (EU): 823 823. German Research Foundation (DFG): FOR 2634/1 TE 1024/1-1. French National Research Agency (ANR): ANR-16-CE31-0013. Alexander von Humboldt Foundation. European Research Council (ERC): 678 194. European Research Council (ERC): 742 095. National Aeronautics & Space Administration (NASA). National Science Foundation (NSF). National Aeronautics & Space Administration (NASA): NNG05GF22G. National Science Foundation (NSF): AST-0909182, AST-1 313 422

    Designing international public sector accounting standards: An analysis of constituents’ participation through comment letters

    Get PDF
    Harmonization of public sector accounting is attracting increasing attention from scholars and practitioners. A focal component of this phenomenon is the setting of accounting standards, whose legitimacy is paramount to their application. As participation by constituents is considered fundamental for ensuring this legitimacy, in this study, we focus on participation through comment letters in the due process. In particular, we explore the type of respondents, their geographical area, their agreement/disagreement with the documents prepared by the International Public Sector Accounting Standards Board (IPSASB) and the issues of importance to them, through an analysis of the comment letters submitted for six projects launched over the period 2017–2020 by the IPSASB. Furthermore, we analyze some factors that may affect countries’ participation in the due process. The analysis enriches our understanding of the IPSASB’s due process and provides relevant insights for the growing research into accounting standard-setting

    A comprehensive framework for the activation, management, and evaluation of Co-production in the public sector

    Get PDF
    Co-production analyses the practices in which state or firms and lay actors work together in any phase of the production cycle. In the public sector, citizens are not seen as mere recipients of services but as co-producers at different stages. Scholarly interest in co-production has grown steadily in the past years. However, the research has yet to integrate the many co-production concepts into a distinctive theoretical comprehensive framework able to strengthen the understanding of the interrelated dynamics at play. The article conducts a systematic in- depth qualitative review of the co-production literature for the public sector. The results highlight the main components into four pillars of a comprehensive theoretical framework to guide scholars and practitioners in the activation and management of co-production as well as in the evaluation of its outcomes. The article concludes by formulating a future research agenda for co-production in the public sector
    • 

    corecore