663 research outputs found

    Galactic conformity and central/satellite quenching, from the satellite profiles of M* galaxies at 0.4 < z < 1.9 in the UKIDSS UDS

    Get PDF
    We explore the redshift evolution of a curious correlation between the star formation properties of central galaxies and their satellites (‘galactic conformity') at intermediate to high redshift (0.4 9.7, around central galaxies at the characteristic Schechter function mass, M ∼ M*. We fit the radial profiles of satellite number densities with simple power laws, finding slopes in the range −1.1 to −1.4 for mass-selected satellites, and −1.3 to −1.6 for passive satellites. We confirm the tendency for passive satellites to be preferentially located around passive central galaxies at 3σ significance and show that it exists to at least z ∼ 2. Meanwhile, the quenched fraction of satellites around star-forming galaxies is consistent with field galaxies of equal stellar masses. We find no convincing evidence for a redshift-dependent evolution of these trends. One simple interpretation of these results is that only passive central galaxies occupy an environment that is capable of independently shutting off star formation in satellite galaxies. By examining the satellites of higher stellar mass star-forming galaxies (log(M*/M⊙) > 11), we conclude that the origin of galactic conformity is unlikely to be exclusively due to the host dark matter halo mass. A halo-mass-independent correlation could be established by either formation bias or a more physical connection between central and satellite star formation histories. For the latter, we argue that a star formation (or active galactic nucleus) related outburst event from the central galaxy could establish a hot halo environment which is then capable of quenching both central and satellite galaxie

    Major mergers are not significant drivers of star formation or morphological transformation around the epoch of peak cosmic star formation

    Get PDF
    We investigate the contribution of major mergers (mass ratios > 1:5) to stellar mass growth and morphological transformations around the epoch of peak cosmic star formation (z ~ 2). We visually classify a complete sample of massive (M > 1010M_) galaxies at this epoch, drawn from the CANDELS survey, into late-type galaxies, major mergers, spheroids and disturbed spheroids which show morphological disturbances. Given recent simulation work, which indicates that recent (<0.3-0.4 Gyr) major-merger remnants exhibit clear tidal features in such images, we use the fraction of disturbed spheroids to probe the role of major mergers in driving morphological transformations. The percentage of blue spheroids (i.e. with ongoing star formation) that show morphological disturbances is only 21 +- 4 per cent, indicating that major mergers are not the dominant mechanism for spheroid creation at z ~ 2 - other processes, such as minor mergers or cold accretion are likely to be the main drivers of this process. We also use the rest-frame U-band luminosity as a proxy for star formation to show that only a small fraction of the star formation budget (~3 per cent) is triggered by major mergers. Taken together, our results show that major mergers are not significant drivers of galaxy evolution at z ~ 2

    Program Management versus Portfolio Management in Defense Acquisition

    Get PDF
    Program Management / Faculty ReportAcquisition Research Program Sponsored Report SeriesSponsored Acquisition Research & Technical ReportsThis research performed a gap analysis on the existing Department of Defense (DoD) program management competency standards to determine if changes are required to fully adopt product portfolio management (PPM) strategies in defense acquisition. Current DoD program management standards are compared to the Project Management Institute's Portfolio Management Professional certification standards to analyze alignment and gaps between the standards. Barrier to Implementation (BTI) scores are assigned to address the identified gaps in the DoD standard. The study found that the DoD program management competencies are on average 41% aligned with portfolio management industry standards. The DoD program management competencies are least aligned with the portfolio management domains of governance and strategic alignment. The composite BTI score indicates low to medium level of implementation barriers for most of the gaps. Results indicate that the DoD is capable of conducting PPM, and further research is needed to fully align the current competency standards with industry best practices. Defense acquisition senior leaders should consider formulating DoD portfolio management career field functional competencies to address congressional mandates for portfolio management implementation within the DoD.Approved for public release; distribution is unlimited

    Current status of and future opportunities for digital agriculture in Australia

    Get PDF
    In Australia, digital agriculture is considered immature and its adoption ad hoc, despite a relatively advanced technology innovation sector. In this review, we focus on the technical, governance and social factors of digital adoption that have created a disconnect between technology development and the end user community (farmers and their advisors). Using examples that reflect both successes and barriers in Australian agriculture, we first explore the current enabling technologies and processes, and then we highlight some of the key socio-technical factors that explain why digital agriculture is immature and ad hoc. Pronounced issues include fragmentation of the innovation system (and digital tools), and a lack of enabling legislation and policy to support technology deployment. To overcome such issues and increase adoption, clear value propositions for change are necessary. These value propositions are influenced by the perceptions and aspirations of individuals, the delivery of digitally-enabled processes and the supporting legislative, policy and educational structures, better use/conversion of data generated through technology applications to knowledge for supporting decision making, and the suitability of the technology. Agronomists and early adopter farmers will play a significant role in closing the technology-end user gap, and will need support and training from technology service providers, government bodies and peer-networks. Ultimately, practice change will only be achieved through mutual understanding, ownership and trust. This will occur when farmers and their advisors are an integral part of the entire digital innovation system

    Harmonic E/B decomposition for CMB polarization maps

    Full text link
    The full sky cosmic microwave background polarization field can be decomposed into 'electric' (E) and 'magnetic' (B) components that are signatures of distinct physical processes. We give a general construction that achieves separation of E and B modes on arbitrary sections of the sky at the expense of increasing the noise. When E modes are present on all scales the separation of all of the B signal is no longer possible: there are inevitably ambiguous modes that cannot be separated. We discuss the practicality of performing E/B decomposition on large scales with realistic non-symmetric sky-cuts, and show that separation on large scales is possible by retaining only the well supported modes. The large scale modes potentially contain a great deal of useful information, and E/B separation at the level of the map is essential for clean detection of B without confusion from cosmic variance due to the E signal. We give simple matrix manipulations for creating pure E and B maps of the large scale signal for general sky cuts. We demonstrate that the method works well in a realistic case and give estimates of the performance with data from the Planck satellite. In the appendix we discuss the simple analytic case of an azimuthally symmetric cut, and show that exact E/B separation is possible on an azimuthally symmetric cut with a finite number of non-intersecting circular cuts around foreground sources.Comment: Fixed numerical bug in tensor C_l: Planck detection probability results updated (supersedes PRD version). Sample code and additional examples available at http://cosmologist.info/polar

    Evidence for a correlation between the sizes of quiescent galaxies and local environment to z ~ 2

    Full text link
    We present evidence for a strong relationship between galaxy size and environment for the quiescent population in the redshift range 1 < z < 2. Environments were measured using projected galaxy overdensities on a scale of 400 kpc, as determined from ~ 96,000 K-band selected galaxies from the UKIDSS Ultra Deep Survey (UDS). Sizes were determined from ground-based K-band imaging, calibrated using space-based CANDELS HST observations in the centre of the UDS field, with photometric redshifts and stellar masses derived from 11-band photometric fitting. From the resulting size-mass relation, we confirm that quiescent galaxies at a given stellar mass were typically ~ 50 % smaller at z ~ 1.4 compared to the present day. At a given epoch, however, we find that passive galaxies in denser environments are on average significantly larger at a given stellar mass. The most massive quiescent galaxies (M_stellar > 2 x 10^11 M_sun) at z > 1 are typically 50 % larger in the highest density environments compared to those in the lowest density environments. Using Monte Carlo simulations, we reject the null hypothesis that the size-mass relation is independent of environment at a significance > 4.8 sigma for the redshift range 1 < z < 2. In contrast, the evidence for a relationship between size and environment is much weaker for star-forming galaxies.Comment: Accepted for publication in MNRAS. 16 pages, 11 figures, 6 table

    Global Analysis of Transcription Start Sites and Enhancers in Endometrial Stromal Cells and Differences Associated with Endometriosis.

    Get PDF
    Identifying tissue-specific molecular signatures of active regulatory elements is critical to understanding gene regulatory mechanisms. In this study, transcription start sites (TSS) and enhancers were identified using Cap analysis of gene expression (CAGE) across endometrial stromal cell (ESC) samples obtained from women with (n = 4) and without endometriosis (n = 4). ESC TSSs and enhancers were compared to those reported in other tissue and cell types in FANTOM5 and were integrated with RNA-seq and ATAC-seq data from the same samples for regulatory activity and network analyses. CAGE tag count differences between women with and without endometriosis were statistically tested and tags within close proximity to genetic variants associated with endometriosis risk were identified. Over 90% of tag clusters mapping to promoters were observed in cells and tissues in FANTOM5. However, some potential cell-type-specific promoters and enhancers were also observed. Regions of open chromatin identified using ATAC-seq provided further evidence of the active transcriptional regions identified by CAGE. Despite the small sample number, there was evidence of differences associated with endometriosis at 210 consensus clusters, including IGFBP5, CALD1 and OXTR. ESC TSSs were also located within loci associated with endometriosis risk from genome-wide association studies. This study provides novel evidence of transcriptional differences in endometrial stromal cells associated with endometriosis and provides a valuable cell-type specific resource of active TSSs and enhancers in endometrial stromal cells

    Altered differentiation of endometrial mesenchymal stromal fibroblasts is associated with endometriosis susceptibility.

    Get PDF
    Cellular development is tightly regulated as mature cells with aberrant functions may initiate pathogenic processes. The endometrium is a highly regenerative tissue, shedding and regenerating each month. Endometrial stromal fibroblasts are regenerated each cycle from mesenchymal stem cells and play a pivotal role in endometriosis, a disease characterised by endometrial cells that grow outside the uterus. Why the cells of some women are more capable of developing into endometriosis lesions is not clear. Using isolated, purified and cultured endometrial cells of mesenchymal origin from 19 women with (n = 10) and without (n = 9) endometriosis we analysed the transcriptome of 33,758 individual cells and compared these to clinical characteristics and in vitro growth profiles. We show purified mesenchymal cell cultures include a mix of mesenchymal stem cells and two endometrial stromal fibroblast subtypes with distinct transcriptomic signatures indicative of varied progression through the differentiation processes. The fibroblast subgroup characterised by incomplete differentiation was predominantly (81%) derived from women with endometriosis and exhibited an altered in vitro growth profile. These results uncover an inherent difference in endometrial cells of women with endometriosis and highlight the relevance of cellular differentiation and its potential to contribute to disease susceptibility
    • …
    corecore