1,630 research outputs found

    Clustering Measurements of broad-line AGNs: Review and Future

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    Despite substantial effort, the precise physical processes that lead to the growth of super-massive black holes in the centers of galaxies are still not well understood. These phases of black hole growth are thought to be of key importance in understanding galaxy evolution. Forthcoming missions such as eROSITA, HETDEX, eBOSS, BigBOSS, LSST, and Pan-STARRS will compile by far the largest ever Active Galactic Nuclei (AGNs) catalogs which will allow us to measure the spatial distribution of AGNs in the universe with unprecedented accuracy. For the first time, AGN clustering measurements will reach a level of precision that will not only allow for an alternative approach to answering open questions in AGN/galaxy co-evolution but will open a new frontier, allowing us to precisely determine cosmological parameters. This paper reviews the large-scale clustering measurements of broad line AGNs. We summarize how clustering is measured and which constraints can be derived from AGN clustering measurements, we discuss recent developments, and we briefly describe future projects that will deliver extremely large AGN samples which will enable AGN clustering measurements of unprecedented accuracy. In order to maximize the scientific return on the research fields of AGN/galaxy evolution and cosmology, we advise that the community develop a full understanding of the systematic uncertainties which will, in contrast to today's measurement, be the dominant source of uncertainty.Comment: referred review article, paper is in print in Acta Polytechnica, 7 pages, 3 figure

    The spatial clustering of ROSAT All-Sky Survey Active Galactic Nuclei IV. More massive black holes reside in more massive dark matter halos

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    This is the fourth paper in a series that reports on our investigation of the clustering properties of active galactic nuclei (AGN) identified in the ROSAT All-Sky Survey (RASS) and Sloan Digital Sky Survey (SDSS). In this paper we investigate the cause of the X-ray luminosity dependence of the clustering of broad-line, luminous AGN at 0.16<z<0.36. We fit the H-alpha line profile in the SDSS spectra for all X-ray and optically-selected broad-line AGN, determine the mass of the super-massive black hole (SMBH), M_BH, and infer the accretion rate relative to Eddington (L/L_EDD). Since M_BH and L/L_EDD are correlated, we create AGN subsamples in one parameter while maintaining the same distribution in the other parameter. In both the X-ray and optically-selected AGN samples we detect a weak clustering dependence with M_BH and no statistically significant dependence on L/L_EDD. We find a difference of up to 2.7sigma when comparing the objects that belong to the 30% least and 30% most massive M_BH subsamples, in that luminous broad-line AGN with more massive black holes reside in more massive parent dark matter halos at these redshifts. These results provide evidence that higher accretion rates in AGN do not necessarily require dense galaxy environments in which more galaxy mergers and interactions are expected to channel large amounts of gas onto the SMBH. We also present semi-analytic models which predict a positive M_DMH dependence on M_BH, which is most prominent at M_BH ~ 10^{8-9} M_SUN.Comment: 24 pages, 16 figures, 2015 ApJ, 815, 2

    Libraries, Linguistics and Artificial Intelligence: J. C. R. Licklider and the Libraries of the Future

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    In 1965, J. C. R. Licklider published a book regarding the “Libraries of the future”. This book was soon almost forgotten when a different paradigm of computing, partially created by Licklider himself, became dominant. However, a re-reading of the book, in hindsight, not only gives a glimpse of a seminal moment in the history human interaction with computers but allows a chance to see in a different light many issues still relevant to the field.In 1965, J. C. R. Licklider published a book regarding the “Libraries of the future”. This book was soon almost forgotten when a different paradigm of computing, partially created by Licklider himself, became dominant. However, a re-reading of the book, in hindsight, not only gives a glimpse of a seminal moment in the history human interaction with computers but allows a chance to see in a different light many issues still relevant to the field

    Functional changes during hospital stay in older patients admitted to an acute care ward : a multicenter observational study

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    Objectives: Changes in physical performance during hospital stay have rarely been evaluated. In this study, we examined functional changes during hospital stay by assessing both physical performance and activities of daily living. Additionally, we investigated characteristics of older patients associated with meaningful in-hospital improvement in physical performance. Methods: The CRiteria to assess appropriate Medication use among Elderly complex patients project recruited 1123 patients aged >= 65 years, consecutively admitted to geriatric or internal medicine acute care wards of seven Italian hospitals. We analyzed data from 639 participating participants with a Mini Mental State Examination score >= 18/30. Physical performance was assessed by walking speed and grip strength, and functional status by activities of daily living at hospital admission and at discharge. Meaningful improvement was defined as a measured change of at least 1 standard deviation. Multivariable logistic regression models predicting meaningful improvement, included age, gender, type of admission (through emergency room or elective), and physical performance at admission. Results: Mean age of the study participants was 79 years (range 65-98), 52% were female. Overall, mean walking speed and grip strength performance improved during hospital stay (walking speed improvement: 0.04 +/- 0.20 m/s, p<0.001; grip strength improvement: 0.43 +/- 5.66 kg, p = 0.001), no significant change was observed in activities of daily living. Patients with poor physical performance at admission had higher odds for in-hospital improvement. Conclusion: Overall, physical performance measurements show an improvement during hospital stay. The margin for meaningful functional improvement is larger in patients with poor physical function at admission. Nevertheless, most of these patients continue to have poor performance at discharge

    White paper on the future of plasma science and technology in plastics and textiles

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    This is the peer reviewed version of the following article: “Uros, C., Walsh, J., Cernák, M., Labay, C., Canal, J.M., Canal, C. (2019) White paper on the future of plasma science and technology in plastics and textiles. Plasma processes and polymers, 16 1 which has been published in final form at [doi: 10.1002/ppap.201700228]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."This white paper considers the future of plasma science and technology related to the manufacturing and modifications of plastics and textiles, summarizing existing efforts and the current state‐of‐art for major topics related to plasma processing techniques. It draws on the frontier of plasma technologies in order to see beyond and identify the grand challenges which we face in the following 5–10 years. To progress and move the frontier forward, the paper highlights the major enabling technologies and topics related to the design of surfaces, coatings and materials with non‐equilibrium plasmas. The aim is to progress the field of plastics and textile production using advanced plasma processing as the key enabling technology which is environmentally friendly, cost efficient, and offers high‐speed processingPeer ReviewedPostprint (author's final draft

    Taste, Information, and Asset Prices: Implications for the Valuation of CSR

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    Firms often undertake activities that do not necessarily increase cash flows (e.g., costly investments in corporate social responsibility or CSR), and some investors value these non cash activities (i.e., they have a “taste” for these activities). We develop a model to capture this phenomenon and focus on the asset-pricing implications of differences in investors’ tastes for firms’ activities and outputs. Our model shows that, first, investor taste differences provide a basis for investor clientele effects that are endogenously determined by the shares demanded by different types of investors. Second, because the market must clear at one price, investors’ demands are influenced by all dimensions of firm output even if their preferences are only over some dimensions. Third, information releases cause trading volume, even when all investors have the same information. Fourth, investor taste provides a rationale for corporate spin-offs that help firms better target their shareholder bases. Finally, individual social responsibility can lead to corporate social responsibility when managers care about stock price because price reacts to investments in CSR activities
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