580 research outputs found

    The Opacity of Spiral Galaxy Disks VIII: Structure of the Cold ISM

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    The quantity of dust in a spiral disk can be estimated using the dust's typical emission or the extinction of a known source. In this paper, we compare two techniques, one based on emission and one on absorption, applied on sections of fourteen disk galaxies. The two measurements reflect, respectively the average and apparent optical depth of a disk section. Hence, they depend differently on the average number and optical depth of ISM structures in the disk. The small scale geometry of the cold ISM is critical for accurate models of the overall energy budget of spiral disks. ISM geometry, relative contributions of different stellar populations and dust emissivity are all free parameters in galaxy Spectral Energy Distribution (SED) models; they are also sometimes degenerate, depending on wavelength coverage. Our aim is to constrain typical ISM geometry. The apparent optical depth measurement comes from the number of distant galaxies seen in HST images through the foreground disk. We measure the IR flux in images from the {\it Spitzer} Infrared Nearby Galaxy Survey in the same section of the disk that was covered by HST. A physical model of the dust is fit to the SED to estimate the dust surface density, mean temperature, and brightness in these disk sections. The surface density is subsequently converted into the average optical depth estimate. The two measurements generally agree. The ratios between the measured average and apparent optical depths of the disk sections imply optically thin clouds in these disks. Optically thick disks, are likely to have more than a single cloud along the line-of-sight.Comment: 31 pages, 5 figures, 4 tables, accepted for publication in A

    The four or more medicines (FOMM) support service:results from an evaluation of a new community pharmacy service aimed at over-65s

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    Background: 57% of all prescriptions dispensed in the UK in 2003 were for people aged ≥60, where ≥20% of them were prescribed ≥ five medicines. Inappropriate prescribing and non-adherence have a significant impact on hospital admissions and patient quality of life. The English government has identified that community pharmacy could make a significant contribution to reducing non-adherence and improving the quality of prescribing, reducing both hospital admissions and medicines wastage. Objective: To evaluate a community pharmacy service aimed at patients over the age of 65 years prescribed four or more medicines. Method: Patients were invited to participate in the service by the community pharmacy team. The pharmacist held regular consultations with the patient and discussed risk of falls, pain management, adherence and general health. They also reviewed the patient’s medication using STOPP/START criteria. Data wereas analysed for the first six months of participation in the service. Key findings: 620 patients were recruited with 441 (71.1%) completing the six month study period. Pharmacists made 142 recommendations to prescribers in 110 patients largely centred on potentially inappropriate prescribing of NSAIDs, PPIs or duplication of therapy. At follow-up there was a significant decrease in the total number of falls (mean -0.116 (-0.217 - -0.014)) experienced and a significant increase in medicines adherence (mean difference in MMAS-8: 0.513 (0.337 – 0.689)) and quality of life. Cost per QALY estimates ranged from £11,885 to £32,466 depending on the assumptions made. Conclusion: By focussing on patients over the age of 65 years with four or more medicines, community pharmacists can improve medicines adherence and patient quality of life

    Gaps in the cloud cover? Comparing extinction measures in spiral disks

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    Dust in galaxies can be mapped by either the FIR/sub-mm emission, the optical or infrared reddening of starlight, or the extinction of a known background source. We compare two dust extinction measurements for a set of fifteen sections in thirteen nearby galaxies, to determine the scale of the dusty ISM responsible for disk opacity: one using stellar reddening and the other a known background source. In our earlier papers, we presented extinction measurements of 29 galaxies, based on calibrated counts of distant background objects identified though foreground disks in HST/WFPC2 images. For the 13 galaxies that overlap with the Spitzer Infrared Nearby Galaxies Survey (SINGS), we now compare these results with those obtained from an I-L color map. Our goal is to determine whether or not a detected distant galaxy indicates a gap in the dusty ISM, and hence to better understand the nature and geometry of the disk extinction. We find that distant galaxies are predominantly in low-extinction sections marked by the color maps, indicating that their number depends both on the cloud cover of {\it Spitzer}-resolved dust structures --mostly the spiral arms--and a diffuse, unresolved underlying disk. We note that our infrared color map (E[I-L]) underestimates the overall dust presence in these disks severely, because it implicitly assumes the presence of a dust screen in front of the stellar distribution.Comment: 22 pages, 2 figures, 3 tables, accepted for publication in A

    From Ideas to Practice, Pilots to Strategy: Practical Solutions and Actionable Insights on How to Do Impact Investing

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    This report is the second publication in the World Economic Forum's Mainstreaming Impact Investing Initiative. The report takes a deeper look at why and how asset owners began to include impact investing in their portfolios and continue to do so today, and how they overcame operational and cultural constraints affecting capital flow. Given that impact investing expertise is spread among dozens if not hundreds of practitioners and academics, the report is a curation of some -- but certainly not all -- of those leading voices. The 15 articles are meant to provide investors, intermediaries and policy-makers with actionable insights on how to incorporate impact investing into their work.The report's goals are to show how mainstream investors and intermediaries have overcome the challenges in the impact investment sector, and to democratize the insights and expertise for anyone and everyone interested in the field. Divided into four main sections, the report contains lessons learned from practitioner's experience, and showcases best practices, organizational structures and innovative instruments that asset owners, asset managers, financial institutions and impact investors have successfully implemented

    The stellar content, metallicity and ionization structure of HII regions

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    Observations of infrared fine-structure lines provide direct information on the metallicity and ionization structure of HII regions and indirectly on the hardness of the radiation field ionizing these nebulae. We have analyzed a sample of Galactic and Magellanic Cloud HII regions observed by the Infrared Space Observatory (ISO) to examine the interplay between stellar content, metallicity and the ionization structure of HII regions. The observed [SIV]10.5/[SIII]18.7 mum and [NeIII]15.5/[NeII]12.8 mum line ratios are shown to be highly correlated over more than two orders of magnitude. We have compared the observed line ratios to the results of photoionization models using different stellar energy distributions. The derived characteristics of the ionizing star depend critically on the adopted stellar model as well as the (stellar) metallicity. We have compared the stellar effective temperatures derived from these model studies for a few well-studied HII regions with published direct spectroscopic determinations of the spectral type of the ionizing stars. This comparison supports our interpretation that stellar and nebular metallicity influences the observed infrared ionic line ratios. We can explain the observed increase in degree of ionization, as traced by the [SIV]\[SIII] and [NeIII]\[NeII] line ratios, by the hardening of the radiation field due to the decrease of metallicity. The implications of our results for the determination of the ages of starbursts in starburst galaxies are assessed.Comment: 9 pages; accepted for publication in A&A; figure 3 modifie

    Visual Similarity Perception of Directed Acyclic Graphs: A Study on Influencing Factors

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    While visual comparison of directed acyclic graphs (DAGs) is commonly encountered in various disciplines (e.g., finance, biology), knowledge about humans' perception of graph similarity is currently quite limited. By graph similarity perception we mean how humans perceive commonalities and differences in graphs and herewith come to a similarity judgment. As a step toward filling this gap the study reported in this paper strives to identify factors which influence the similarity perception of DAGs. In particular, we conducted a card-sorting study employing a qualitative and quantitative analysis approach to identify 1) groups of DAGs that are perceived as similar by the participants and 2) the reasons behind their choice of groups. Our results suggest that similarity is mainly influenced by the number of levels, the number of nodes on a level, and the overall shape of the graph.Comment: Graph Drawing 2017 - arXiv Version; Keywords: Graphs, Perception, Similarity, Comparison, Visualizatio
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