NEREA: Named entity recognition and disambiguation exploiting local document repositories

In this work, we describe the design, development, and deployment of NEREA (Named Entity Recognizer for spEcific Areas), an automatic Named Entity Recognizer and Disambiguation system, developed in collaboration with professional documentalists. The aim of NEREA is to keep accurate and current information about the entities mentioned in a local repository, and then support building appropriate infoboxes, setting out the main data of these entities. It achieves a high performance thanks to the use of classification resources belonging to the local database. With this aim, the system performs tasks of named entity recognition and disambiguation by using three types of knowledge bases: local classification resources, global databases like DBpedia, and its own catalog created by NEREA. The proposed method has been validated with two different datasets and its operation has been tested in English and Spanish. The working methodology is being applied in a real environment of a media with promising results

Fabrication and characterization of Cu reinforced with Y-enriched particles following a novel powder metallurgy route

Dispersion strengthened copper alloys have been produced following an innovative powder metallurgy route. Copper and yttrium acetate powders have been mechanically alloyed and posteriorly thermal treated at 923 K for 3 h and 15 h under a hydrogen atmosphere in order to transform the yttrium acetate into Y2O3. Subsequently, the powders were consolidated by hot isostatic pressing. It has been concluded that the duration of the thermal treatment of the powder is a determining factor in the degree of densification of the alloy. The study of the microstructure by Scanning Electron Microscopy and Electron Backscatter Diffraction has revealed the presence of micrometer and submicrometer grains and nanometric Y-O enriched Cu particles embedded in the copper matrix, the mean grain size being smaller for the sample produced from the powder thermal treated for 15 h. Transmission Electron Microscopy investigations concluded that the nanoparticles exhibit a spherical shape with a size up to 25 nm and correspond to monoclinic Y2O3. Annealing twins have been also observed, especially in the material produced from thermal treated powder for longer. The mechanical properties have been inferred from Vickers microhardness measurements and compression tests. Below 473 K the yield strengths of the produced materials are greater than that of pure copper and above 473 K are close to them. From the study of the thermal properties of the densest material it has been found that its thermal conductivity remains nearly constant in the temperature range 300–773 K, and its value is around 85% the thermal conductivity of CuCrZr, the reference material for ITER.The present work has been supported by the Agencia Estatal de Investigación (PID2019-105325RB-C33 / AEI / 10.13039/501100011033) and by the Regional Government of Madrid through the program TECHNOFUSIÓN(III)CM (S2018/EMT-4437). The support of the Regional Government of Madrid through the multi-annual agreement with UC3M ("Excelencia para el Profesorado Universitario"- EPUC3M14) - Fifth regional research plan 2016-2020 is acknowledge

Microstructure and mechanical properties of hot rolled ODS copper

Dispersion strengthened copper alloys have been produced by following a powder metallurgy route that have consisted of milling copper and yttrium acetate powders in a planetary ball milling and subsequently sintering by hot isostatic pressing (HIP). In order to increase the degree of densification of the materials, they were subjected to a thermal treatment in vacuum and to a hot rolling process at 1173 K. The decomposition of the yttrium acetate during the thermal treatments resulted in the formation of voids, with a loss of densification that could not be satisfactorily improved with the hot rolling processing. The microstructure and the mechanical and thermal properties of the alloys were analyzed by scanning electron microscopy, electron backscattering diffraction, micro and nanohardness measurements, and compression tests and thermal conductivity measurements, both in the range 300–780 K. The best mechanical properties were obtained for the as-HIP material, with a mean grain size of 0.3 ± 0.3 μm and a yield strength value at room temperature of 520 MPa. In contrast, the material with the highest thermal conductivity for the entire range of temperature was found to be the alloy thermal treated in vacuum at 1273 K and later subjected to the hot rolling processing. The different microstructural characteristics of the alloys such as grain size, defects present in the grains and size of voids seems to be responsible of the differences on their thermal conductivity values.The present work has been supported by the Ministerio de Economía y Competitividad of Spain (ENE2015-70300-C3-2-R MINECO/FEDER) and by the Regional Government of Madrid through the program TECHNOFUSIÓN(III)CM (S2018/EMT-4437)

Stellar population and the origin of intra-cluster stars around brightest cluster galaxies: the case of NGC 3311

Context. We investigate the stellar population and the origin of diffuse light around brightest cluster galaxies. Aims. We study the stellar population of the dynamically hot stellar halo of NGC 3311, the brightest galaxy in the Hydra I cluster, and that of photometric substructures in the diffuse light to constrain the origin of these components. Methods. We analyze absorption lines in medium-resolution, long-slit spectra in the wavelength range 4800-5800 angstrom obtained with FORS2 at the Very Large Telescope. We measure the equivalent width of Lick indices out to 20 kpc from the center of NGC 3311 and fit them with stellar population models that account for the [alpha/Fe] overabundance. Results. Stars in the dynamically hot halo of NGC 3311 are old (age > 13 Gyr), metal-poor ([Z/H] ~ -0.35), and alpha-enhanced ([alpha/Fe] ~ 0.48). Together with the high velocity dispersion, these measurements indicate that the stars in the halo were accreted from the outskirts of other early-type galaxies, with a possible contribution from dwarf galaxies. We identify a region in the halo of NGC 3311 associated with a photometric substructure where the stellar population is even more metal-poor ([Z/H] ~ -0.73). In this region, our measurements are consistent with a composite stellar population superposed along the line of sight, consisting of stars from the dynamically hot halo of NGC 3311 and stars stripped from dwarf galaxies. The latter component contributes < 28% to the local surface brightness. Conclusions. The build-up of diffuse light around NGC 3311 is on-going. Based on the observed stellar population properties, the dominant part of these stars may have come from the outskirts of bright early-type galaxies, while stars from stripped dwarf galaxies are presently being added.Comment: 8 pages, 4 figures. Accepted for publication in Astronomy & Astrophysic

Medium-resolution Isaac Newton Telescope library of empirical spectra - II. The stellar atmospheric parameters

We present a homogeneous set of stellar atmospheric parameters (T-eff, log g, [Fe/H]) for MILES, a new spectral stellar library covering the range lambda lambda 3525-7500 angstrom at 2.3 angstrom (FWHM) spectral resolution. The library consists of 985 stars spanning a large range in atmospheric parameters, from super-metal-rich, cool stars to hot, metal-poor stars. The spectral resolution, spectral type coverage and number of stars represent a substantial improvement over previous libraries used in population synthesis models. The atmospheric parameters that we present here are the result of a previous, extensive compilation from the literature. In order to construct a homogeneous data set of atmospheric parameters we have taken the sample of stars of Soubiran, Katz & Cayrel, which has very well determined fundamental parameters, as the standard reference system for our field stars, and have calibrated and bootstrapped the data from other papers against it. The atmospheric parameters for our cluster stars have also been revised and updated according to recent metallicity scales, colour-temperature relations and improved set of isochrones

Measurement of the Stray Light in the Advanced Virgo Input Mode Cleaner Cavity using an instrumented baffle

A new instrumented baffle was installed in Spring 2021 at Virgo surrounding the suspended mirror in the input mode cleaner triangular cavity. It serves as a demonstrator of the technology designed to instrument the baffles in the main arms in the near future. We present, for the first time, results on the measured scattered light distribution inside the cavity as determined by the new device using data collected between May and July 2021, with Virgo in commissioning phase and operating with an input laser power in the cavity of 28.5~W. The sensitivity of the baffle is discussed and the data is compared to scattered light simulations.Comment: 4 pages, 5 figures, 1 tabl

A multiwavelength approach to the SFR estimation in galaxies at intermediate redshifts

We use a sample of 7 starburst galaxies at intermediate redshifts (z ~ 0.4 and z ~ 0.8) with observations ranging from the observed ultraviolet to 1.4 GHz, to compare the star formation rate (SFR) estimators which are used in the different wavelength regimes. We find that extinction corrected Halpha underestimates the SFR, and the degree of this underestimation increases with the infrared luminosity of the galaxies. Galaxies with very different levels of dust extinction as measured with SFR(IR)/SFR(Halpha, uncorrected for extinction) present a similar attenuation A[Halpha], as if the Balmer lines probed a different region of the galaxy than the one responsible for the bulk of the IR luminosity for large SFRs. In addition, SFR estimates derived from [OII]3727 match very well those inferred from Halpha after applying the metallicity correction derived from local galaxies. SFRs estimated from the UV luminosities show a dichotomic behavior, similar to that previously reported by other authors in galaxies at z <~ 0.4. Here we extend this result up to z ~ 0.8. Finally, one of the studied objects is a luminous compact galaxy (LCG) that may be suffering similar dust-enshrouded star formation episodes. These results highlight the relevance of quantifying the actual L(IR) of LCGs, as well as that of a much larger and generic sample of luminous infrared galaxies, which will be possible after the launch of SIRTF.Comment: Accepted for publication in The Astrophysical Journa

ProtoDESI: First On-Sky Technology Demonstration for the Dark Energy Spectroscopic Instrument

The Dark Energy Spectroscopic Instrument (DESI) is under construction to measure the expansion history of the universe using the baryon acoustic oscillations technique. The spectra of 35 million galaxies and quasars over 14,000 square degrees will be measured during a 5-year survey. A new prime focus corrector for the Mayall telescope at Kitt Peak National Observatory will deliver light to 5,000 individually targeted fiber-fed robotic positioners. The fibers in turn feed ten broadband multi-object spectrographs. We describe the ProtoDESI experiment, that was installed and commissioned on the 4-m Mayall telescope from August 14 to September 30, 2016. ProtoDESI was an on-sky technology demonstration with the goal to reduce technical risks associated with aligning optical fibers with targets using robotic fiber positioners and maintaining the stability required to operate DESI. The ProtoDESI prime focus instrument, consisting of three fiber positioners, illuminated fiducials, and a guide camera, was installed behind the existing Mosaic corrector on the Mayall telescope. A Fiber View Camera was mounted in the Cassegrain cage of the telescope and provided feedback metrology for positioning the fibers. ProtoDESI also provided a platform for early integration of hardware with the DESI Instrument Control System that controls the subsystems, provides communication with the Telescope Control System, and collects instrument telemetry data. Lacking a spectrograph, ProtoDESI monitored the output of the fibers using a Fiber Photometry Camera mounted on the prime focus instrument. ProtoDESI was successful in acquiring targets with the robotically positioned fibers and demonstrated that the DESI guiding requirements can be met.Comment: Accepted versio

Metal-THINGS: The association and optical characterization of SNRs with HI holes in NGC 6946

NGC~6946, also known as the `Fireworks' galaxy, is an unusual galaxy that hosts a total of 225 supernova remnant (SNR) candidates, including 147 optically identified with high [SII]/Ha line ratios. In addition, this galaxy shows prominent HI holes, which were analyzed in previous studies. Indeed, the connection between SNRs and HI holes together with their physical implications in the surrounding gas is worth of attention. This paper explores the connection between the SNRs and the HI holes, including an analysis of their physical link to observational optical properties inside and around the rims of the holes, using new integral field unit (IFU) data from the Metal-THINGS survey. We present an analysis combining previously identified HI holes, SNRs candidates, and new integral field unit (IFU) data from Metal-THINGS of the spiral galaxy NGC 6946. We analyze the distributions of the oxygen abundance, star formation rate surface density, extinction, ionization, diffuse ionized gas, and the Baldwin-Phillips-Terlevich classification throughout the galaxy. By analyzing in detail the optical properties of the 121 previously identify HI holes in NGC 6946, we find that the SNRs are concentrated at the rims of the HI holes. Furthermore, our IFU data shows that the star formation rate and extinction are enhanced at the rims of the holes. To a lesser degree, the oxygen abundance and ionization parameter show hints of enhancement on the rims of the holes. Altogether, this provides evidence of induced star formation taking place at the rims of the holes, whose origin can be explained by the expansion of superbubbles created by multiple supernova explosions in large stellar clusters dozens of Myr ago.Comment: Accepted by A&