179 research outputs found

    Evolved galaxies in high-density environments across 2.0z<4.22.0\leq z<4.2 using the ZFOURGE survey

    Full text link
    To explore the role environment plays in influencing galaxy evolution at high redshifts, we study 2.0z<4.22.0\leq z<4.2 environments using the FourStar Galaxy Evolution (ZFOURGE) survey. Using galaxies from the COSMOS legacy field with log(M/M)9.5{\rm log(M_{*}/M_{\odot})}\geq9.5, we use a seventh nearest neighbour density estimator to quantify galaxy environment, dividing this into bins of low, intermediate and high density. We discover new high density environment candidates across 2.0z<2.42.0\leq z<2.4 and 3.1z<4.23.1\leq z<4.2. We analyse the quiescent fraction, stellar mass and specific star formation rate (sSFR) of our galaxies to understand how these vary with redshift and environment. Our results reveal that, across 2.0z<2.42.0\leq z<2.4, the high density environments are the most significant regions, which consist of elevated quiescent fractions, log(M/M)10.2{\rm log(M_{*}/M_{\odot})}\geq10.2 massive galaxies and suppressed star formation activity. At 3.1z<4.23.1\leq z<4.2, we find that high density regions consist of elevated stellar masses but require more complete samples of quiescent and sSFR data to study the effects of environment in more detail at these higher redshifts. Overall, our results suggest that well-evolved, passive galaxies are already in place in high density environments at z2.4z\sim2.4, and that the Butcher-Oemler effect and SFR-density relation may not reverse towards higher redshifts as previously thought.Comment: 11 pages, 5 figures, final version published in PAS

    ZFIRE: A KECK/MOSFIRE Spectroscopic Survey of Galaxies in Rich Environments at z~2

    Get PDF
    We present an overview and the first data release of ZFIRE, a spectroscopic redshift survey of star-forming galaxies that utilizes the MOSFIRE instrument on Keck-I to study galaxy properties in rich environments at 1.5<z<2.51.5<z<2.5. ZFIRE measures accurate spectroscopic redshifts and basic galaxy properties derived from multiple emission lines. The galaxies are selected from a stellar mass limited sample based on deep near infra-red imaging (KAB<25\mathrm{K_{AB}<25}) and precise photometric redshifts from the ZFOURGE and UKIDSS surveys as well as grism redshifts from 3DHST. Between 2013--2015 ZFIRE has observed the COSMOS and UDS legacy fields over 13 nights and has obtained 211 galaxy redshifts over 1.57<z<2.661.57<z<2.66 from a combination of nebular emission lines (such as \Halpha, \NII, \Hbeta, \OII, \OIII, \SII) observed at 1--2\micron. Based on our medium-band NIR photometry, we are able to spectrophotometrically flux calibrate our spectra to \around10\% accuracy. ZFIRE reaches 5σ5\sigma emission line flux limits of \around3×1018 erg/s/cm2\mathrm{3\times10^{-18}~erg/s/cm^2} with a resolving power of R=3500R=3500 and reaches masses down to \around109^{9}\msol. We confirm that the primary input survey, ZFOURGE, has produced photometric redshifts for star-forming galaxies (including highly attenuated ones) accurate to Δz/(1+zspec)=0.015\Delta z/(1+z\mathrm{_{spec})}=0.015 with 0.7%0.7\% outliers. We measure a slight redshift bias of <0.001<0.001, and we note that the redshift bias tends to be larger at higher masses. We also examine the role of redshift on the derivation of rest-frame colours and stellar population parameters from SED fitting techniques. The ZFIRE survey extends spectroscopically-confirmed z2z\sim 2 samples across a richer range of environments, here we make available the first public release of the data for use by the community.\footnote{\url{http://zfire.swinburne.edu.au}}Comment: Published in ApJ. Data available at http://zfire.swinburne.edu.au, Code for figures at https://github.com/themiyan/zfire_survey, 31 pages, 24 figure

    ZFOURGE: Using Composite Spectral Energy Distributions to Characterize Galaxy Populations at 1<z<4

    Get PDF
    We investigate the properties of galaxies as they shut off star formation over the 4 billion years surrounding peak cosmic star formation. To do this we categorize 7000\sim7000 galaxies from 1<z<41<z<4 into 9090 groups based on the shape of their spectral energy distributions (SEDs) and build composite SEDs with R50R\sim 50 resolution. These composite SEDs show a variety of spectral shapes and also show trends in parameters such as color, mass, star formation rate, and emission line equivalent width. Using emission line equivalent widths and strength of the 4000\AA\ break, D(4000)D(4000), we categorize the composite SEDs into five classes: extreme emission line, star-forming, transitioning, post-starburst, and quiescent galaxies. The transitioning population of galaxies show modest Hα\alpha emission (EWREST40EW_{\rm REST}\sim40\AA) compared to more typical star-forming composite SEDs at log10(M/M)10.5\log_{10}(M/M_\odot)\sim10.5 (EWREST80EW_{\rm REST}\sim80\AA). Together with their smaller sizes (3 kpc vs. 4 kpc) and higher S\'ersic indices (2.7 vs. 1.5), this indicates that morphological changes initiate before the cessation of star formation. The transitional group shows a strong increase of over one dex in number density from z3z\sim3 to z1z\sim1, similar to the growth in the quiescent population, while post-starburst galaxies become rarer at z1.5z\lesssim1.5. We calculate average quenching timescales of 1.6 Gyr at z1.5z\sim1.5 and 0.9 Gyr at z2.5z\sim2.5 and conclude that a fast quenching mechanism producing post-starbursts dominated the quenching of galaxies at early times, while a slower process has become more common since z2z\sim2.Comment: Accepted for publication in The Astrophysical Journa

    Acquisition and loss of CTX-M plasmids in Shigella species associated with MSM transmission in the UK

    Get PDF
    Shigellosis in men who have sex with men (MSM) is caused by multidrug resistant Shigellae, exhibiting resistance to antimicrobials including azithromycin, ciprofloxacin and more recently the third-generation cephalosporins. We sequenced four bla (CTX-M-27)-positive MSM Shigella isolates (2018–20) using Oxford Nanopore Technologies; three S. sonnei (identified as two MSM clade 2, one MSM clade 5) and one S. flexneri 3a, to explore AMR context. All S. sonnei isolates harboured Tn7/Int2 chromosomal integrons, whereas S. flexneri 3a contained the Shigella Resistance Locus. All strains harboured IncFII pKSR100-like plasmids (67-83kbp); where present bla (CTX-M-27) was located on these plasmids flanked by IS26 and IS903B, however bla (CTX-M-27) was lost in S. flexneri 3a during storage between Illumina and Nanopore sequencing. IncFII AMR regions were mosaic and likely reorganised by IS26; three of the four plasmids contained azithromycin-resistance genes erm(B) and mph(A) and one harboured the pKSR100 integron. Additionally, all S. sonnei isolates possessed a large IncB/O/K/Z plasmid, two of which carried aph(3’)-Ib/aph(6)-Id/sul2 and tet(A). Monitoring the transmission of mobile genetic elements with co-located AMR determinants is necessary to inform empirical treatment guidance and clinical management of MSM-associated shigellosis

    'Focusing' in motivational interviewing: development of a training tool for practitioners

    Get PDF
    Rationale, aims and objectives: Motivational Interviewing (MI) is an individual-level approach to behaviour change that has been evaluated in over 600 randomised clinical trials across multiple settings. Increasingly, research efforts focus on how MI works and how it can best be integrated into public health and clinical programmes. As the application of MI expands, a key integration challenge involves specifying the focus of a conversation such that a practitioner might ignite and intensify a patient’s internal motivation for change related to that focus. At present, this challenge is poorly conceptualised. We aimed to clarify the construct of “focusing” and to develop a practical tool that can be used to develop and assess practitioner competence. Method: First we reviewed validated MI measures to elucidate current conceptualisations of focusing. Second, we identified practitioner speech acts that led to topic transitions. We then drafted the first version of MIFI. A gold standard rater, together with one expert MI and 3 non-expert MI raters, each used MIFI to coded 20 audio recordings from a feasibility study of MI and breastfeeding maintenance (n=170 observations). Internal consistency and inter-rater reliability analyses were conducted. Results: Published MI measures include ‘focusing’ as a strategy to agree a target change or to hold attention on that change target. We observed practitioners create or shift focus using 4 skills: questions, listening statements, giving information or meta-statements. Moderate to strong correlations were demonstrated between 4 of 5 global measures on the MIFI. Reliability estimates were good to excellent overall (5 coder ICCs>0.65), fair to excellent for the non-expert coding group (ICCs>0.55) and for the best coding pair (MI expert and non-expert ICCs >0.52). Conclusion: We offer conceptual clarity about focusing in MI and have developed a tool to train practitioners in “focusing” when integrating MI into healthcare and public health interventions

    Tracking counterpart signatures in Saturn's auroras and ENA imagery during large-scale plasma injection events

    Get PDF
    Saturn's morningside auroras consist mainly of rotating, transient emission patches, following periodic reconnection in the magnetotail. Simultaneous responses in global energetic neutral atom (ENA) emissions have been observed at similar local times, suggesting a link between the auroras and large‐scale injections of hot ions in the outer magnetosphere. In this study, we use Cassini's remote sensing instruments to observe multiple plasma injection signatures within coincident auroral and ENA imagery, captured during 9 April 2014. Kilometric radio emissions also indicate clear injection activity. We track the motion of rotating signatures in the auroras and ENAs to test their local time relationship. Two successive auroral signatures—separated by ~4 hr UT—form postmidnight before rotating to the dayside while moving equatorward. The first has a clear ENA counterpart, maintaining a similar local time mapping throughout ~9 hr observation. Mapping of the ionospheric equatorward motion post‐dawn indicates a factor ~5 reduction of the magnetospheric source region's radial speed at a distance of ~14‐20 RS, possibly a plasma or magnetic boundary. The second auroral signature has no clear ENA counterpart; viewing geometry was relatively unchanged, so the ENAs were likely too weak to detect by this time. A third, older injection signature, seen in both auroral and ENA imagery on the nightside, may have been sustained by field‐aligned currents linked with the southern planetary period oscillation system, or the re‐energization of ENAs around midnight local times. The ENA injection signatures form near magnetic longitudes associated with magnetotail thinning

    Epigenetic control of alternative mRNA processing at the imprinted Herc3/Nap1l5 locus

    Get PDF
    Alternative polyadenylation increases transcriptome diversity by generating multiple transcript isoforms from a single gene. It is thought that this process can be subject to epigenetic regulation, but few specific examples of this have been reported. We previously showed that the Mcts2/H13 locus is subject to genomic imprinting and that alternative polyadenylation of H13 transcripts occurs in an allele-specific manner, regulated by epigenetic mechanisms. Here, we demonstrate that allele-specific polyadenylation occurs at another im-printed locus with similar features. Nap1l5 is a retrogene expressed from the paternally inherited allele, is situated within an intron of a ‘host ’ gene Herc3, and overlaps a CpG island that is differen-tially methylated between the parental alleles. In mouse brain, internal Herc3 polyadenylation sites upstream of Nap1l5 are used on the pater-nally derived chromosome, from which Nap1l5 is expressed, whereas a downstream site is used more frequently on the maternally derived chromo-some. Ablating DNA methylation on the maternal allele at the Nap1l5 promoter increases the use of an internal Herc3 polyadenylation site and alters exon splicing. These changes demonstrate the influ-ence of epigenetic mechanisms in regulating Herc3 alternative mRNA processing. Internal Herc3 polyadenylation correlates with expression levels of Nap1l5, suggesting a possible role for transcrip-tional interference. Similar mechanisms may regulate alternative polyadenylation elsewhere in the genome

    Northern grazing carbon farming – integrating production and greenhouse gas outcomes 1 : Climate Clever Beef Final Report

    Get PDF
    This project targeted three large and diverse regions across northern Australia: the Queensland Gulf, the Queensland Fitzroy Basin and the Northern Territory (Victoria River District, Douglas Daly and Barkly Tableland regions). Eleven grazing businesses across three broad regions were engaged as case studies to undertake demonstrations and evaluations within their businesses. These businesses manage more than 1,281,000 ha and 97,600 cattle. The project provided an excellent opportunity to capitalize on established networks and genuine producer interest and participation built up in recent initiatives (e.g. CCRP Climate Clever Beef (Bray et al. 2014), Northern Grazing Systems project (Phelps et al. 2014), RELRP, SCaRP, SavannaPlan, CQ Beef). The project team included research and extension professionals with decades of combined experience working with northern beef producers. The knowledge and analytical tools developed during previous projects identified practices to: reduce the greenhouse gas emissions impact of beef businesses, manage climate variability, improve land condition and increase business profitability

    Northern grazing carbon farming – integrating production and greenhouse gas outcomes 1 : Climate Clever Beef Final Report

    Get PDF
    This project targeted three large and diverse regions across northern Australia: the Queensland Gulf, the Queensland Fitzroy Basin and the Northern Territory (Victoria River District, Douglas Daly and Barkly Tableland regions). Eleven grazing businesses across three broad regions were engaged as case studies to undertake demonstrations and evaluations within their businesses. These businesses manage more than 1,281,000 ha and 97,600 cattle. The project provided an excellent opportunity to capitalize on established networks and genuine producer interest and participation built up in recent initiatives (e.g. CCRP Climate Clever Beef (Bray et al. 2014), Northern Grazing Systems project (Phelps et al. 2014), RELRP, SCaRP, SavannaPlan, CQ Beef). The project team included research and extension professionals with decades of combined experience working with northern beef producers. The knowledge and analytical tools developed during previous projects identified practices to: reduce the greenhouse gas emissions impact of beef businesses, manage climate variability, improve land condition and increase business profitability
    corecore