We present the first simultaneous spectral energy distribution (SED) of M87 core at a scale of 0.4 arcsec ( ∼ 32 pc) across the electromagnetic spectrum. Two separate, quiescent, and active states ...are sampled that are characterized by a similar featureless SED of power-law form, and that are thus remarkably different from that of a canonical active galactic nuclei or a radiatively inefficient accretion source. We show that the emission from a jet gives an excellent representation of the core of M87 core covering ten orders of magnitude in frequency for both the active and the quiescent phases. The inferred total jet power is, however, one to two orders of magnitude lower than the jet mechanical power reported in the literature. The maximum luminosity of a thin accretion disc allowed by the data yields an accretion rate of < 6 × 10− 5 M⊙ yr− 1, assuming 10 per cent efficiency. This power suffices to explain M87 radiative luminosity at the jet frame, it is however two to three order of magnitude below that required to account for the jet's kinetic power. The simplest explanation is variability, which requires the core power of M87 to have been two to three orders of magnitude higher in the last 200 yr. Alternatively, an extra source of power may derive from black hole spin. Based on the strict upper limit on the accretion rate, such spin power extraction requires an efficiency an order of magnitude higher than predicted from magnetohydrodynamic simulations, currently in the few hundred per cent range.
Spectral energy distributions (SEDs) of the central few tens of parsec region of some of the nearest, most well-studied, active galactic nuclei (AGN) are presented. These genuine AGN-core SEDs, ...mostly from Seyfert galaxies, are characterized by two main features: an infrared (IR) bump with the maximum in the 2–10 μm range and an increasing X-ray spectrum with frequency in the 1 to ∼200 keV region. These dominant features are common to Seyfert type 1 and 2 objects alike. In detail, type 1 AGN are clearly distinguished from type 2 by their high spatial resolution SEDs: type 2 AGN exhibit a sharp drop shortwards of 2 μm, with the optical to UV region being fully absorbed; type 1s instead show a gentle 2 μm drop ensued by a secondary, partially absorbed optical to UV emission bump. On the assumption that the bulk of optical to UV photons generated in these AGN is reprocessed by dust and re-emitted in the IR in an isotropic manner, the IR bump luminosity represents ≳70 per cent of the total energy output in these objects, and the second energetically important contribution is the high energies above 20 keV. Galaxies selected by their warm IR colours, i.e. presenting a relatively flat flux distribution in the 12–60 μm range, have often being classified as AGN. The results from these high spatial resolution SEDs question this criterion as a general rule. It is found that the intrinsic shape of the infrared SED of an AGN and inferred bolometric luminosity largely depart from those derived from large aperture data. AGN luminosities can be overestimated by up to two orders of magnitude if relying on IR satellite data. We find these differences to be critical for AGN luminosities below or about 1044 erg s−1. Above this limit, AGN tend to dominate the light of their host galaxy regardless of the integration aperture size used. Although the number of objects presented in this work is small, we tentatively mark this luminosity as a threshold to identify galaxy-light-dominated versus AGN-dominated objects.
A novel balanced differential bandpass filter implemented in coplanar waveguide (CPW) technology is presented. The filter is based on the use of two magnetically coupled CPW folded-stepped impedance ...resonators. The use of magnetic coupling, instead of the more common electric coupling, provides inherent common-mode rejection. Measured and simulated results demonstrate the benefits of the proposed balanced filter.
Ni phytomining is a promising technology for Ni recovery from low-grade ores such as ultramafic soils. Metal-hyperaccumulators are good candidates for phytomining due to their extraordinary capacity ...for Ni accumulation. However, many of these plants produce a low biomass, which makes the use of agronomic techniques for improving their growth necessary.
In this study, the Ni hyperaccumulators Alyssum serpyllifolium ssp. lusitanicum, A. serpyllifolium ssp. malacitanum, Alyssum bertolonii and Noccaea goesingense were evaluated for their Ni phytoextraction efficiency from a Ni-rich serpentine soil. Effects of soil inorganic fertilisation (100:100:125kgNPKha−1) and soil organic amendment addition (2.5, 5 or 10% compost) on plant growth and Ni accumulation were determined. All soil treatments greatly improved plant growth, but the highest biomass production was generally found after addition of 2.5 or 5% compost (w/w). The most pronounced beneficial effects were observed for N. goesingense. Total Ni phytoextracted from soils was significantly improved using both soil treatments (inorganic and organic), despite the decrease observed in soil Ni availability and shoot Ni concentrations in compost-amended soils. The most promising results were found using intermediate amount of compost, indicating that these types of organic wastes can be incorporated into phytomining systems.
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•The low biomass of most Ni-hyperaccumulator plants can limit the applicability of phytomining techniques at field scale•The use of traditional agronomic practises such as fertilisation can improve plant establishment and biomass production of these plant species•Changes in soil Ni availability, shoot biomass production and Ni accumulation by four Ni-hyperaccumulator species were evaluated after soil inorganic fertilisation (NPK) or compost amendment•Intermediate doses of compost amendment had a stronger effect on Ni yield, mainly due to the enhanced shoot biomass•The use of organic wastes as amendments in phytomining permits the recycling of these residues
The present work studied the uptake of 8:2 perfluoroalkyl phosphate diester (diPAP) by two different crops (lettuce and carrot) and two different amended soils. Firstly, the possible degradation of ...8:2 diPAP in the absence of crop was studied and 8:2 monoPAP (monophosphate), 8:2 FTCA (saturated fluorotelomer carboxylate), 8:2 FTUCA (unsaturated fluorotelomer carboxylate), 7:3 FTCA (saturated fluorotelomer carboxylate), PFHpA (perfluoroheptanoic acid), PFHxA (perfluorohexanoic acid) and PFOA (perfluorooctanoic acid) were detected. In the presence of crops, different degradation products were detected in the soil and, while PFNA (perfluorononanoic acid), PFHpA, PFHxA, PFPeA (perfluoropentacoic acid), PFBA (perfluorobutanoic acid), 7:3 FTCA and PFOA were determined in the cultivation media when carrot was grown, PFOA was the only degradation product detected in the case of lettuce experiments.
Regarding the uptake in carrot, all the degradation products except 7:3 FTCA were translocated from the soil to the carrot. Carrot core, peel and leaves bioconcentration factors, BCFs, were determined for 8:2 diPAP and its degradation products. Values lower than method detection limits for core and low BCFs in peel (0.025–0.042) and leaves (0.028–0.049) were achieved for 8:2 diPAP. Regarding to the degradation products, the higher their water solubility, the higher the plant translocation. In this sense, the lower the carbon chain length of PFCAs, the higher the BCFs determined (PFBA > PFHxA > PFHpA > PFOA > PFNA). In general, lower total BCFs were achieved when the total organic carbon of the soils increased. For lettuce experiments, 8:2 diPAP (0.04–0.18) and PFOA (0.28–1.57) were only determined in lettuce heart.
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•8:2 diPAP was degraded in the presence and absence of crops (lettuce and carrot).•PFOA was always the major metabolite both in the presence and absence of crops.•Low accumulation in carrot and lettuce of 8:2 diPAP was observed.•The higher the solubility of the metabolites, the higher the BCFs observed in carrot.•PFOA was the only metabolite detected in lettuce uptake experiments.
The current Web of Data is producing increasingly large RDF datasets. Massive publication efforts of RDF data driven by initiatives like the Linked Open Data movement, and the need to exchange large ...datasets has unveiled the drawbacks of traditional RDF representations, inspired and designed by a document-centric and human-readable Web. Among the main problems are high levels of verbosity/redundancy and weak machine-processable capabilities in the description of these datasets. This scenario calls for efficient formats for publication and exchange.
This article presents a binary RDF representation addressing these issues. Based on a set of metrics that characterizes the skewed structure of real-world RDF data, we develop a proposal of an RDF representation that modularly partitions and efficiently represents three components of RDF datasets: Header information, a Dictionary, and the actual Triples structure (thus called HDT). Our experimental evaluation shows that datasets in HDT format can be compacted by more than fifteen times as compared to current naive representations, improving both parsing and processing while keeping a consistent publication scheme. Specific compression techniques over HDT further improve these compression rates and prove to outperform existing compression solutions for efficient RDF exchange.
Sewage sludge, which acts like a sink for many pollutants, including metals, pathogens and organic pollutants, that are not completely removed in waste water treatment plants (WWTPs), is applied as a ...nutrient rich organic fertilizer in many agricultural applications. In the present work, carrot and lettuce crops were grown in two different compost amended soils fortified with perfluorooctanoic acid (PFOA), perfluorosulfonate acid (PFOS) and perfluorosulfonamide (FOSA) and cultivated in a greenhouse. The plants were harvested and divided into root core, root peel and leaves in the case of carrots and into heart and leaves for lettuces. Concentrations for all the different compartments were determined to assess the bioconcentration factors (BCFs) and the plant distribution of the target analytes. The highest carrot BCFs for PFOA and PFOS were determined in the leaves (0.6–3.4), while lower values were calculated in the core (0.05–0.6) and the peel (0.05–1.9) compartments. However, PFOA was taken up in the translocation stream and accumulated more than PFOS in the edible part of lettuce.
FOSA was totally degraded in the presence of carrot; however, a lower FOSA degradation was observed in presence of the lettuce, which was dependent on the total organic carbon (TOC) content of the soil. The higher the TOC value, the higher the FOSA degradation observed. No degradation was observed in the crop absence.
In the case of the carrot experiments, different polymeric materials (polyethersulfone, PES, polyoxymethylene, and silicone rod) were tested to predict the concentration in the cultivation media. A high correlation (r2>0.63) was observed for the BCFs in the PES and in the carrot core and peel for PFOA and PFOS. It could be, concluded that the PES can be used as a first approach for the determination of the uptake of compounds such as PFOS and PFOA in carrot.
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•BCFLeaves>BCFPeel~BCFCore for PFOS and PFOA in carrot•Leaves PFOA concentrations were obtained higher than PFOS and FOSA.•In presence of crop FOSA was partially (lettuce) or totally (carrot) degraded.•Analytes presence in leaves was due to root uptake and not to foliar uptake.•Good correlation between BCF PES and BCF Peel was obtained for carrot.
Type 2 active galactic nuclei (AGN) are by definition nuclei in which the broad-line region and continuum light are hidden at optical/UV wavelengths by dust. Via accurate registration of infrared ...(IR) Very Large Telescope adaptive optics images with optical Hubble Space Telescope images we unambiguously identify the precise location of the nucleus of a sample of nearby, type 2 AGN. Dust extinction maps of the central few kpc of these galaxies are constructed from optical–IR colour images, which allow tracing the dust morphology at scales of few pc. In almost all cases, the IR nucleus is shifted by several tens of pc from the optical peak and its location is behind a dust filament, prompting to this being a major, if not the only, cause of the nucleus obscuration. These nuclear dust lanes have extinctions AV
≥ 3 − 6 mag, sufficient to at least hide the low-luminosity AGN class, and in some cases are observed to connect with kpc-scale dust structures, suggesting that these are the nuclear fueling channels. A precise location of the ionized gas Hα and Si vii 2.48 μ coronal emission lines relative to those of the IR nucleus and dust is determined. The Hα peak emission is often shifted from the nucleus location and its sometimes conical morphology appears not to be caused by a nuclear – torus – collimation but to be strictly defined by the morphology of the nuclear dust lanes. Conversely, Si vii 2.48 μ emission, less subjected to dust extinction, reflects the truly, rather isotropic, distribution of the ionized gas. All together, the precise location of the dust, ionized gas and nucleus is found compelling enough to cast doubts on the universality of the pc-scale torus and supports its vanishing in low-luminosity AGN. Finally, we provide the most accurate position of the NGC 1068 nucleus, located at the south vertex of cloud B.
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