2,617 research outputs found

    Finding bright <i>z</i> ≥ 6.6 Ly <i>α</i> emitters with lensing: prospects for <i>Euclid</i>

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    We model the z≥6.6z \geq 6.6 Lyα\alpha luminosity function to estimate the number of lensed high−z-z Lyα\alpha emitters that may be detected by the Euclid Deep Survey. To span the whole range of possible predictions we exploit two Lyα\alpha luminosity function models and two strong gravitational lensing models from the literature. We show that the planned Euclid Deep Survey observing 40 deg2^2 over the 920-1850 nm wavelength range down to a flux limit of Flim=5×10−17 F_{lim}=5\times10^{-17}\,erg s−1 ^{-1}\,cm−2^{-2} will enable us to find between ∼0.85\sim 0.85 and ∼1.82\sim 1.82 deg−2^{-2} lensed Lyα\alpha emitters at z≥6.6z \geq 6.6 depending on the adopted Lyα\alpha luminosity function and strong gravitational lensing model. The obvious [OII], [OIII] and Hβ\beta contaminants of the Lyα\alpha lensed population will be identified with the help of Euclid's spectral resolving power, while the SKA will enable the identification of the interloper population of Hα\alpha emitters. By combining Euclid and the SKA, we will thus be able to identify, for the first time, a sample of ∼34\sim 34 to ∼73\sim 73 lensed Lyα\alpha emitters at z≥6.6z \geq 6.6.Comment: Accepted for publication in MNRAS on 20 June 2017. (NEW: Amended Latex

    Evaluation of the phosphomannose isomerase-based selection system for gene transfer in grape

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    The suitability of the PMI-based system for efficient gene transfer in grape was assessed on V. vinifera ‘Brachetto’ and ‘Chardonnay’ and the rootstock '110 Richter'. The effect of mannose on non-transformed tissues was evaluated during a long culture period in the crucial stages of morphogenesis from callus to plantlet. Grape tissues of the genotypes used were affected by mannose as the carbohydrate source, damage, however, appeared after extremely long culture times. In addition, plantlets were regenerated from embryogenic calli after co-culture with Agrobacterium LBA 4404 carrying the manA gene in the PMI-GUS-Intron plasmid based on the pNOV2819 vector by Syngenta (Positech® system). Plants recovered after selection in the presence of mannose were found to be non-transgenic for the manA gene. Accordingly, PMI seems to be an unsuitable alternative to traditional marker gene selection for successful gene transfer in grape.

    Costs associated with the management of waste from healthcare facilities: an analysis at national and site level

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    Given rising spend on the provision of healthcare services, the sustainable management of waste from healthcare facilities is increasingly becoming a focus as a means of reducing public health risks and financial costs. Using data on per capita healthcare spend at the national level, as well as a case study of a hospital in Italy, this study examined the relationship between trends in waste generation and the associated costs of managing the waste. At the national level, healthcare spend as a percentage of gross domestic product positively correlated with waste arisings. At the site level, waste generation and type were linked to department type and clinical performance, with the top three highest generating departments of hazardous healthcare waste being anaesthetics (5.96 kg day-1 bed-1), paediatric and intensive care (3.37 kg day-1 bed-1) and gastroenterology-digestive endoscopy (3.09 kg day-1 bed-1). Annual overall waste management costs were US5,079,191,orapproximatelyUS5,079,191, or approximately US2.36 kg-1, with the management of the hazardous fraction of the waste being highest at $US3,707,939. In Italy, reduction in both waste arisings and the associated costs could be realised through various means, including improved waste segregation, and linking the TARI tax to waste generation

    The Stripe 82 1-2 GHz Very Large Array Snapshot Survey: Multiwavelength Counterparts

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    We have combined spectrosopic and photometric data from the Sloan Digital Sky Survey (SDSS) with 1.41.4 GHz radio observations, conducted as part of the Stripe 82 1−21-2 GHz Snapshot Survey using the Karl G. Jansky Very Large Array (VLA), which covers ∼100\sim100 sq degrees, to a flux limit of 88 μ\muJy rms. Cross-matching the 11 76811\,768 radio source components with optical data via visual inspection results in a final sample of 4 7954\,795 cross-matched objects, of which 1 9961\,996 have spectroscopic redshifts and 2 7992\,799 objects have photometric redshifts. Three previously undiscovered Giant Radio Galaxies (GRGs) were found during the cross-matching process, which would have been missed using automated techniques. For the objects with spectroscopy we separate radio-loud Active Galactic Nuclei (AGN) and star-forming galaxies (SFGs) using three diagnostics and then further divide our radio-loud AGN into the HERG and LERG populations. A control matched sample of HERGs and LERGs, matched on stellar mass, redshift and radio luminosity, reveals that the host galaxies of LERGs are redder and more concentrated than HERGs. By combining with near-infrared data, we demonstrate that LERGs also follow a tight K−zK-z relationship. These results imply the LERG population are hosted by population of massive, passively evolving early-type galaxies. We go on to show that HERGs, LERGs, QSOs and star-forming galaxies in our sample all reside in different regions of a WISE colour-colour diagram. This cross-matched sample bridges the gap between previous `wide but shallow' and `deep but narrow' samples and will be useful for a number of future investigations.Comment: 17 pages, 19 figures. Resubmitted to MNRAS after the initial comment

    Digital threats to democracy: comparative lessons and possible remedies

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    We introduce a special issue that collects eight articles, comprising research from twenty-three countries and four continents on the sources, impact on citizens, and possible remedies to various digital threats to democracy, ranging from disinformation to hate speech to state interference with online freedoms. We set these contributions against the backdrop of a profound change in how scholars think about the implications of digital media for democracy. From the utopianism that prevailed from the 1990s until the early 2010s, the post-2016 reckoning has led to a change in the kinds of questions scholars ask, with the focus gradually shifting to investigations of the threats, rather than the benefits, of the Internet. The eight contributions presented in this special issue employ a variety of disciplinary approaches and methods, often comparing different countries, to address some of the most pressing questions on how the Internet can hinder the feasibility and well-functioning of democracy around the world. We conclude by setting out three challenges for future research on digital media and politics: a growing but still partial understanding of the extent and impact of the main digital threats to democracy; the risk that the dominant approaches become overly pessimistic, or founded on weak normative grounds; and the risk that research overemphasizes direct and short-term implications of digital threats on individuals and specific groups at the expense of indirect and medium-term effects on collective norms and expectations of behavior

    SR-FTIR microscopy for the study of residues on Palaeolithic stone tools: Looking for a methodological protocol

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    In this paper, we use SR-FTIR microscopy to analyse residues identified on seven lithic artefacts from the Evolved Epigravettian layer 9c2 of the cave site of Grotta Paglicci (Apulia, southern Italy). Synchrotron radiation, thanks to its properties that particularly increase the sensitivity of FTIR microscopy, allows the analysis of samples of microscopic size and the characterisation of even highly degraded compounds, such as the residues of materials worked by Palaeolithic stone tools or complex compounds used for hafting. This pilot study has been carried out in the framework of a project concerning the reconstruction of hunting technologies between the Middle and Upper Palaeolithic. The preliminary results allowed us to focus on the issues of our methodological approach and to show the potential of the SR-FTIR microscopy for the analysis of residues on lithic implements

    Evolution of the far-infrared luminosity functions in the Spitzer Wide-area Infrared Extragalactic Legacy Survey

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    We present new observational determination of the evolution of the rest-frame 70 and 160 micron and total infrared (TIR) galaxy luminosity functions (LFs) using 70 micron data from the Spitzer Wide-area Infrared Extragalactic Legacy Survey (SWIRE). The LFs were constructed for sources with spectroscopic redshifts only in the XMM-LSS and Lockman Hole fields from the SWIRE photometric redshift catalogue. The 70 micron and TIR LFs were constructed in the redshift range 0<z<1.2 and the 160 micron LF was constructed in the redshift range 0<z<0.5 using a parametric Bayesian and the vmax methods. We assume in our models, that the faint-end power-law index of the LF does not evolve with redshifts. We find the the double power-law model is a better representation of the IR LF than the more commonly used power-law and Gaussian model. We model the evolution of the FIR LFs as a function of redshift where where the characteristic luminosity, L∗L^\ast evolve as \propto(1+z)^{\alpha_\textsc{l}}. The rest-frame 70 micron LF shows a strong luminosity evolution out to z=1.2 with alpha_l=3.41^{+0.18}_{-0.25}. The rest-frame 160 micron LF also showed rapid luminosity evolution with alpha_l=5.53^{+0.28}_{-0.23} out to z=0.5. The rate of evolution in luminosity is consistent with values estimated from previous studies using data from IRAS, ISO and Spitzer. The TIR LF evolves in luminosity with alpha_l=3.82^{+0.28}_{-0.16} which is in agreement with previous results from Spitzer 24 micron which find strong luminosity evolution. By integrating the LF we calculated the co-moving IR luminosity density out to z=1.2, which confirm the rapid evolution in number density of LIRGs and ULIRGs which contribute ~68^{+10}_{-07} % to the co-moving star formation rate density at z=1.2. Our results based on 70 micron data confirms that the bulk of the star formation at z=1 takes place in dust obscured objects.Comment: 17 pages, 14 figure

    Accidental exposure to politics on social media as online participation equalizer in Germany, Italy, and the United Kingdom

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    We assess whether and how accidental exposure to political information on social media contributes to citizens\u2019 online political participation in comparative perspective. Based on three online surveys of samples representative of German, Italian, and British Internet users in the aftermath of the 2014 European Parliament elections, we find that accidental exposure to political information on social media is positively and significantly correlated with online participation in all three countries, particularly so in Germany where overall levels of participation were lower. We also find that interest in politics moderates this relationship so that the correlation is stronger among the less interested than among the highly interested. These findings suggest that inadvertent encounters with political content on social media are likely to reduce the gap in online engagement between citizens with high and low interest in politics, potentially broadening the range of voices that make themselves heard
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