5,294 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

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    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 Andalucía)

    Far-infrared line spectra of active galaxies from the Herschel/PACS Spectrometer: the complete database

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    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 μm\mu m 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]25.9μm\mu m/[OIII]88μm\mu m vs [NeIII]15.6μm\mu m/[NeII]12.8μm\mu m diagram is proposed as the best diagnostic to separate: i)i) AGN activity from any kind of star formation; and ii)ii) low-metallicity dwarf galaxies from starburst galaxies. Current stellar atmosphere models fail to reproduce the observed [OIV]25.9μm\mu m/[OIII]88μm\mu m ratios, which are much higher when compared to the predicted values. Finally, the ([NeIII]15.6μm\mu m + [NeII]12.8μm\mu m)/([SIV]10.5μm\mu m + [SIII]18.7μm\mu m) 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 (1<z<41 < z < 4). 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 metacaolín bajo ensayos de resistencia al fuego

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    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 geopolímeros compuestas de cenizas volantes, metacaolín 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 días de curado a 20 °C y un 45% de humedad relativa, diferentes ensayos fueron realizados en los geopolímeros obtenidos: fisicoquímicos (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 físicas, mecánicas y de resistencia al fuego sin ningún problema medioambiental

    Production of new neutron-rich isotopes of heavy elements in fragmentation reactions of 238^{238}U projectiles at 1 A GeV

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    The production of heavy neutron-rich nuclei has been investigated using cold fragmentation reactions of 238^{238}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: 205^{205}Pt, 207−210^{207-210}Au, 211−216^{211-216}Hg, 213−217^{213-217}Tl, 215−220^{215-220}Pb, 219−224^{219-224}Bi, 221−227^{221-227}Po, 224−229^{224-229}At, 229−231^{229-231}Rn and 233^{233}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

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    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

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    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

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    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

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    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

    Long-term follow-up of prophylactic mesh reinforcement after emergency laparotomy. A retrospective controlled study

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    Prevention of incisional hernias with a prophylactic mesh in emergency surgery is controversial. The present study aimed to analyze the long-term results of prophylactic mesh used for preventing incisional hernia after emergency midline laparotomies. This study was a registered (NCT04578561) retrospective analysis of patients who underwent an emergency midline laparotomy between January 2009 and July 2010 with a follow-up period of longer than 2 years. Long-term outcomes and risk factors for the development of incisional hernias between patients who received a prophylactic reinforcement mesh (Group M) and suture (Group S) were compared. From an initial 266 emergency midline laparotomies, 187 patients were included. The median follow-up time was 64.4 months (SD 35). Both groups had similar characteristics, except for a higher rate of previous operations (62 vs. 43.2%; P = 0.01) and operation due to a revision laparotomy (32.5 vs.13%; P = 0.02) in the M group. During follow-up, 29.9% of patients developed an incisional hernia (Group S 36.6% vs. Group M 14.3%; P = 0.002). Chronic mesh infections were diagnosed in 2 patients, but no mesh explants were needed, and no patient in the M group developed chronic pain. Long-term risk factors for incisional hernia were as follows: smoking (HR = 2.47; 95% CI 1.318-4.624; P = 0.05), contaminated surgery (HR = 2.98; 95% CI 1.142-7.8; P = 0.02), surgical site infection (SSI; HR = 3.83; 95% CI 1.86-7.86; P = 0.001), and no use of prophylactic mesh (HR = 5.09; 95% CI 2.1-12.2; P = 0.001). Incidence of incisional hernias after emergency midline laparotomies is high and increases with time. High-risk patients, contaminated surgery, and surgical site infection (SSI) benefit from mesh reinforcement. Prophylactic mesh use is safe and feasible in emergencies with a low long-term complication rate. Trial registration: NCT04578561
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