5,609 research outputs found
Assessment of geodiversity in the southern part of the Central Iberian Zone (Jaén Province): usefulness for delimiting and managing natural protected areas
To explore the relationship between geodiversity and borders of natural protected areas, we studied the northern part of Jaén Province (southern Spain), where the southern sector of the Central Iberian Massif, the Betic Cordillera and the Guadalquivir foreland basin come together. Moreover, several natural protected areas (NPAs) are located here. To approach the topic, we defined the geodiversity index as the sum of partial indices: lithological, geomorphological, palaeontological, pedological, minerals, hydrology and geosites. This made it possible to derive a map of the geodiversity index and a map of geodiversity gradient. Analysis of their distribution shows that almost 80% of the territory has values of medium, high and very high
geodiversity, but these zones are situated outside the borders of the NPAs. A similar study considering two biological indices (endangered species and biodiversity) shows a good correlation between the limits of NPAs and the higher values of these indices. Thus, an absence of correlation between the geodiversity index and biological indices is clearly detected. These results are not in agreement with the definition of NPAs in the current Spanish laws of nature conservation.This research was funded by the Project
Evaluación de la geodiversidad y del patrimonio geológico. Utilidad
para la delimitación y gestión de espacios naturales protegidos.
Aplicación en parques y monumentos naturales del norte de la
Provincia de Jaén (Centre for Advanced Studies in Earth Sciences,
University of Jaén, Spain) and by the Research Group RNM-200 (Junta
de AndalucÃa)
Far-infrared line spectra of active galaxies from the Herschel/PACS Spectrometer: the complete database
We present a coherent database of spectroscopic observations of far-IR
fine-structure lines from the Herschel/PACS archive for a sample of 170 local
AGN, plus a comparison sample of 20 starburst galaxies and 43 dwarf galaxies.
Published Spitzer/IRS and Herschel/SPIRE line fluxes are included to extend our
database to the full 10-600 spectral range. The observations are
compared to a set of CLOUDY photoionisation models to estimate the above
physical quantities through different diagnostic diagrams. We confirm the
presence of a stratification of gas density in the emission regions of the
galaxies, which increases with the ionisation potential of the emission lines.
The new [OIV]25.9/[OIII]88 vs [NeIII]15.6/[NeII]12.8 diagram is proposed as the best diagnostic to separate: AGN activity
from any kind of star formation; and low-metallicity dwarf galaxies from
starburst galaxies. Current stellar atmosphere models fail to reproduce the
observed [OIV]25.9/[OIII]88 ratios, which are much higher when
compared to the predicted values. Finally, the ([NeIII]15.6 +
[NeII]12.8)/([SIV]10.5 + [SIII]18.7) ratio is proposed as
a promising metallicity tracer to be used in obscured objects, where optical
lines fail to accurately measure the metallicity. The diagnostic power of mid-
to far-infrared spectroscopy shown here for local galaxies will be of crucial
importance to study galaxy evolution during the dust-obscured phase at the peak
of the star formation and black-hole accretion activity (). This
study will be addressed by future deep spectroscopic surveys with present and
forthcoming facilities such as JWST, ALMA, and SPICA.Comment: Accepted for publication in the ApJ
Propiedades de paneles geopoliméricos basados en ceniza volante y metacaolÃn bajo ensayos de resistencia al fuego
This paper presents the results of a study about the effect of fire on geopolymer paste composed of fly ashes, metakaolin and sodium silicate. 2 cm thick, 28 cm high and 18 cm wide panels were filled with the paste obtained. After 28 days of curing at 20 °C and 45% of relative humidity, different tests were carried out in the geopolymers: physico-chemical (density, water absorption, porosity), mechanical (flexural and compressive strength), fire resistance and environmental (leaching and radioactivity). The panels manufactured have been compared with other commercial panels in order to determine the recycling possibilities of fly ashes in manufacturing new fire-insulating geopolymers. The panels obtained can be utilized for the production of interior wall materials, with a good physical, mechanical, fire resistant properties without any environmental problem.Este documento presenta los resultados de un estudio sobre el efecto del fuego sobre pastas de geopolÃmeros compuestas de cenizas volantes, metacaolÃn y silicato sódico. Con la pasta obtenida se han rellenado paneles de dimensiones 2 cm de espesor, 28 cm de altura y 18 cm de ancho. Tras 28 dÃas de curado a 20 °C y un 45% de humedad relativa, diferentes ensayos fueron realizados en los geopolÃmeros obtenidos: fisicoquÃmicos (densidad, absorción de agua, porosidad), mecánicos (resistencia a compresión y a flexión), de resistencia al fuego y medioambientales (lixiviación y radioactividad). Los paneles fabricados han sido comparados con paneles comerciales para determinar las posibilidades de reciclaje de las cenizas volantes para la fabricación de nuevos productos geopoliméricos con propiedades aislantes al fuego. Los paneles obtenidos pueden ser utilizados para la producción de paredes interiores, con buenas propiedades fÃsicas, mecánicas y de resistencia al fuego sin ningún problema medioambiental
Service discovery
Semantic service discovery is the process of locating Web Services based on the description of their functional and non-functional semantics. Both service oriented computing and the semantic Web envision intelligent agents to proactively pursue this task on behalf of their clients. Service discovery can be performed in different ways depending on the service description framework, on means of service selection, and on its coordination through assisted mediation or in a peer-to-peer fashion.info:eu-repo/semantics/publishedVersio
Production of new neutron-rich isotopes of heavy elements in fragmentation reactions of U projectiles at 1 A GeV
The production of heavy neutron-rich nuclei has been investigated using cold
fragmentation reactions of U projectiles at relativistic energies. The
experiment performed at the high-resolving-power magnetic spectrometer FRS at
GSI allowed to identify 45 new heavy neutron-rich nuclei: Pt,
Au, Hg, Tl, Pb, Bi,
Po, At, Rn and Fr. The production
cross sections of these nuclei were also determined and used to benchmark
reaction codes that predict the production of nuclei far from stability.Comment: 5 pages, 2 figure
Production of medium-mass neutron-rich nuclei in reactions induced by 136Xe projectiles at 1 A GeV on a beryllium target
Production cross sections of medium-mass neutron-rich nuclei obtained in the
fragmentation of 136Xe projectiles at 1 A GeV have been measured with the
FRagment Separator (FRS) at GSI. 125Pd was identified for the first time. The
measured cross sections are compared to 238U fission yields and model
calculations in order to determine the optimum reaction mechanism to extend the
limits of the chart of the nuclides around the r-process waiting point at N=82.Comment: 9 pages, 6 figure
Evaporation residues produced in spallation of 208Pb by protons at 500A MeV
The production cross sections of fragmentation-evaporation residues in the
reaction Pb+p at 500A MeV have been measured using the inverse-kinematics
method and the FRS spectrometer (GSI). Fragments were identified in nuclear
charge using ionisation chambers. The mass identification was performed
event-by-event using the B-rho - TOF - Delta-E technique. Although
partially-unresolved ionic charge states induced an ambiguity on the mass of
some heavy fragments, production rates could be obtained with a high accuracy
by systematically accounting for the polluting ionic charge states. The
contribution of multiple reactions in the target was subtracted using a new,
partly self-consistent code. The isobaric distributions are found to have a
shape very close to the one observed in experiments at higher energy. Kinematic
properties of the fragments were also measured. The total and the isotopic
cross sections, including charge-pickup cross sections, are in good agreement
with previous measurements. The data are discussed in the light of previous
spallation measurements, especially on lead at 1 GeV
Pressure dependence of the Griffiths-like phase in 5:4 intermetallics
We report a study of the effect of hydrostatic pressure (P) on the Griffiths-like phase in selected compounds of
the R5(SixGe1 ? x)4 family of alloys (Tb4.925La0.075Si2Ge2 and Gd5Ge4) which present either the Gd5Si2Ge2-type (monoclinic, M) or the Sm5Ge4-type [orthorhombic-II, O(II)] structural phases at room temperature. The downward deviation in the inverse low-field dc susceptibility ??1 dc from the Curie-Weiss law below a characteristic temperature TG indicates that the Griffiths-like phase exists at pressures up to 10 kbar. From the obtained T-P phase diagrams, the pressure coefficient of the Griffiths-like temperature, dT G/dP, has been determined. These results are compared with those obtained in Dy5Si3Ge in a previous work. The dT G/dP coefficient is strongly dependent on the nature (first or second order) of the long-range order (FM or AFM) transition. This effect can be ascribed to a different structural character of the clusters within the Griffiths phase. A ratio of ?0.5 between the dT G/dP and the pressure coefficient of long-range magnetic ordering temperatures, dTC,N/dP (TC, ferromagnetic; TN , antiferromagnetic), is found in all the studied compounds.Work at the University of Zaragoza is supported by the Spanish Ministerio de Ciencia, Innovación y Universidades through Project No. MAT2017-82970-C2-2-R and the Aragon Regional Government (Grant No. E28_20R). Work at the University of Cantabria is supported by the Spanish Ministerio de Ciencia, Innovación y Universidades through Project No. MAT2017-83631-C3-R
Hardware-efficient entangled measurements for variational quantum algorithms
Variational algorithms have received significant attention in recent years due to their potential to solve practical problems in noisy intermediate-scale quantum (NISQ) devices. A fundamental step of these algorithms is the evaluation of the expected value of Hamiltonians, and hence, efficient schemes to perform this task are required. The standard approach employs local measurements of Pauli operators and requires a large number of circuits. An alternative is to make use of entangled measurements, which significantly reduces the number of circuits but involves entangling gates between non-physically connected qubits, introducing intermediate entangling operations that increase the depth of the circuits. As a solution to this problem we propose hardware-efficient entangled measurements (HEEM), that is, measurements that only permit entanglement between physically connected qubits. We show that this strategy enhances the evaluation of molecular Hamiltonians in NISQ devices, reducing the number of circuits required without increasing their depth. We provide quantitative metrics of how this approach offers better results than only local measurements and arbitrarily entangled ones. We estimate with classical simulators and quantum hardware the ground state energy of the H2O molecule by the variational quantum eigensolver using HEEM
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