1,856 research outputs found

    High star formation rates as the origin of turbulence in early and modern disk galaxies

    Full text link
    High spatial and spectral resolution observations of star formation and kinematics in early galaxies have shown that two-thirds are massive rotating disk galaxies with the remainder being less massive non-rotating objects. The line of sight averaged velocity dispersions are typically five times higher than in today's disk galaxies. This has suggested that gravitationally-unstable, gas-rich disks in the early Universe are fuelled by cold, dense accreting gas flowing along cosmic filaments and penetrating hot galactic gas halos. However these accreting flows have not been observed, and cosmic accretion cannot power the observed level of turbulence. Here we report on a new sample of rare high-velocity-dispersion disk galaxies we have discovered in the nearby Universe where cold accretion is unlikely to drive their high star-formation rates. We find that the velocity dispersion is most fundamentally correlated with their star-formation rates, and not their mass nor gas fraction, which leads to a new picture where star formation itself is the energetic driver of galaxy disk turbulence at all cosmic epochs.Comment: 9 pages, 2 figures, Supplimentary Info available at: http://pulsar.swin.edu.au/~agreen/nature/sigma_mean_arXiv.pdf. Accepted for publication in Natur

    User centered ecological interface design (UCEID): A novel method applied to the problem of safe and user-friendly interaction between drivers and autonomous vehicles

    Get PDF
    © Springer International Publishing AG 2018. User Centered Ecological Interface Design (UCEID) is a novel Human Factors method that integrates relationships between Ecological Interface Design (EID) and inclusive Human Centered Design. It combines existing methodology from the Cognitive Work Analysis (CWA) framework [1–3] and Inclusive User Centered Design [4, 5]. This paper offers a practical guide to UCEID by providing a high-level summary for practitioners using the example of vehicle to driver handover in a BASt Level 3 autonomous vehicle

    Discursive positioning and planned change in organizations

    Get PDF
    This study uses discursive positioning theory to explore how planned change messages influence organizational members’ identity and the way they experienced organizational change. Based on an in-depth case study of a home healthcare and hospice organization that engaged in a multiyear planned change process, our analysis suggests that workers experienced salient change messages as constituting unfavorable identities, which were associated with the experiences of violation, recitation, habituation, or reservation. Our study also explores the way discursive and material contexts enabled and constrained the governing board’s change messages as they responded to external and internal audiences. We highlight the importance of viewing messaging as a process of information transfer as well as discursive construction, which has important implications for the way change agents approach issues of sense making, emotionality, resistance, and materiality during planned change processes.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

    Methanobactin and the Link Between Copper and Bacterial Methane Oxidation

    Get PDF
    Methanobactins (mbs) are low-molecular-mass (<1,200 Da) copper-binding peptides, or chalkophores, produced by many methane-oxidizing bacteria (methanotrophs). These molecules exhibit similarities to certain iron-binding siderophores but are expressed and secreted in response to copper limitation. Structurally, mbs are characterized by a pair of heterocyclic rings with associated thioamide groups that form the copper coordination site. One of the rings is always an oxazolone and the second ring an oxazolone, an imidazolone, or a pyrazinedione moiety. The mb molecule originates from a peptide precursor that undergoes a series of posttranslational modifications, including (i) ring formation, (ii) cleavage of a leader peptide sequence, and (iii) in some cases, addition of a sulfate group. Functionally, mbs represent the extracellular component of a copper acquisition system. Consistent with this role in copper acquisition, mbs have a high affinity for copper ions. Following binding, mbs rapidly reduce Cu2+ to Cu1+. In addition to binding copper, mbs will bind most transition metals and near-transition metals and protect the host methanotroph as well as other bacteria from toxic metals. Several other physiological functions have been assigned to mbs, based primarily on their redox and metal-binding properties. In this review, we examine the current state of knowledge of this novel type of metal-binding peptide. We also explore its potential applications, how mbs may alter the bioavailability of multiple metals, and the many roles mbs may play in the physiology of methanotrophs

    The hand of Homo naledi

    Get PDF
    A nearly complete right hand of an adult hominin was recovered from the Rising Star cave system, South Africa. Based on associated hominin material, the bones of this hand are attributed to Homo naledi. This hand reveals a long, robust thumb and derived wrist morphology that is shared with Neandertals and modern humans, and considered adaptive for intensified manual manipulation. However, the finger bones are longer and more curved than in most australopiths, indicating frequent use of the hand during life for strong grasping during locomotor climbing and suspension. These markedly curved digits in combination with an otherwise human-like wrist and palm indicate a significant degree of climbing, despite the derived nature of many aspects of the hand and other regions of the postcranial skeleton in H. naledi

    Wake up, wake up! It's me! It's my life! patient narratives on person-centeredness in the integrated care context: a qualitative study

    Get PDF
    Person-centered care emphasizes a holistic, humanistic approach that puts patients first, at the center of medical care. Person-centeredness is also considered a core element of integrated care. Yet typologies of integrated care mainly describe how patients fit within integrated services, rather than how services fit into the patient's world. Patient-centeredness has been commonly defined through physician's behaviors aimed at delivering patient-centered care. Yet, it is unclear how 'person-centeredness' is realized in integrated care through the patient voice. We aimed to explore patient narratives of person-centeredness in the integrated care context

    Questions on causality and responsibility arising from an outbreak of Pseudomonas aeruginosa infections in Norway

    Get PDF
    In 2002, Norway experienced a large outbreak of Pseudomonas aeruginosa infections in hospitals with 231 confirmed cases. This fuelled intense public and professional debates on what were the causes and who were responsible. In epidemiology, other sciences, in philosophy and in law there is a long tradition of discussing the concept of causality. We use this outbreak as a case; apply various theories of causality from different disciplines to discuss the roles and responsibilities of some of the parties involved. Mackie's concept of INUS conditions, Hill's nine viewpoints to study association for claiming causation, deterministic and probabilistic ways of reasoning, all shed light on the issues of causality in this outbreak. Moreover, applying legal theories of causation (counterfactual reasoning and the "but-for" test and the NESS test) proved especially useful, but the case also illustrated the weaknesses of the various theories of causation
    corecore