1,618 research outputs found

    Intrinsic AGN SED & black hole growth in the Palomar--Green quasars

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    We present a new analysis of the PG quasar sample based on Spitzer and Herschel observations. (I) Assuming PAH-based star formation luminosities (L_SF) similar to Symeonidis et al. (2016, S16), we find mean and median intrinsic AGN spectral energy distributions (SEDs). These, in the FIR, appear hotter and significantly less luminous than the S16 mean intrinsic AGN SED. The differences are mostly due to our normalization of the individual SEDs, that properly accounts for a small number of very FIR-luminous quasars. Our median, PAH-based SED represents ~ 6% increase on the 1-243 micron luminosity of the extended Mor & Netzer (2012, EM12) torus SED, while S16 find a significantly larger difference. It requires large-scale dust with T ~ 20 -- 30 K which, if optically thin and heated by the AGN, would be outside the host galaxy. (II) We also explore the black hole and stellar mass growths, using L_SF estimates from fitting Herschel/PACS observations after subtracting the EM12 torus contribution. We use rough estimates of stellar mass, based on scaling relations, to divide our sample into groups: on, below and above the star formation main sequence (SFMS). Objects on the SFMS show a strong correlation between star formation luminosity and AGN bolometric luminosity, with a logarithmic slope of ~ 0.7. Finally we derive the relative duty cycles of this and another sample of very luminous AGN at z = 2 -- 3.5. Large differences in this quantity indicate different evolutionary pathways for these two populations characterised by significantly different black hole masses.Comment: Accepted for publication in MNRA

    Job and Worker Turnover in German Establishments

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    We use a simple regression-based approach to measure the relationship between employment growth, hirings and separations in a large panel of German establishments over the period 1993-2009. Although the average level of hiring and separation is much lower in Germany than in the US, as expected, we find that the relationship between employment growth and worker flows in German establishments is very similar to the behaviour of US establishments described in Davis, Faberman & Haltiwanger (2006, 2011), and quite different to the behaviour of French establishments described in Abowd, Corbel & Kramarz (1999). The relationship is very stable over time, even during the most recent economic crisis, and across different types of establishment.job turnover, worker turnover, hirings and separations

    Cyclic sums, network sharing and restricted edge cuts in graphs with long cycles

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    Cyclic Sums, Network Sharing and Restricted Edge Cuts in Graphs with Long Cycles Dieter Rautenbach , Lutz Volkmann Preprint series: 07-06, 8 MSC 2000 05A17 Partitions of integers 05C40 Connectivity Abstract We study graphs G = (V,E) containing a long cycle which for given integers a1, a2, ..., ak 2 N have an edge cut whose removal results in k components with vertex sets V1, V2, ..., Vk such that |Vi| ai for 1 i k. Our results closely relate to problems and recent research in network sharing and network reliability. Keywords: restricted edge connectivity, arbitrarily vertex decomposable graph, network reliability, network sharin

    On Ī±rĪ³s(k)-perfect graphs

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    AbstractFor some integer kā©¾0 and two graph parameters Ļ€ and Ļ„, a graph G is called Ļ€Ļ„(k)-perfect, if Ļ€(H)āˆ’Ļ„(H)ā©½k for every induced subgraph H of G. For rā©¾1 let Ī±r and Ī³r denote the r-(distance)-independence and r-(distance)-domination number, respectively. In (J. Graph Theory 32 (1999) 303ā€“310), I. Zverovich gave an ingenious complete characterization of Ī±1Ī³1(k)-perfect graphs in terms of forbidden induced subgraphs. In this paper we study Ī±rĪ³s(k)-perfect graphs for r,sā©¾1. We prove several properties of minimal Ī±rĪ³s(k)-imperfect graphs. Generalizing Zverovich's main result in (J. Graph Theory 32 (1999) 303ā€“310), we completely characterize Ī±2rāˆ’1Ī³r(k)-perfect graphs for rā©¾1. Furthermore, we characterize claw-free Ī±2Ī³2(k)-perfect graphs

    Selection of research fellowship recipients by committee peer review. Reliability, fairness and predictive validity of Board of Trustees' decisions

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    Summary: In science, peer review is the best-established method of assessing manuscripts for publication and applications for research fellowships and grants. However, the fairness of peer review, its reliability and whether it achieves its aim to select the best science and scientists has often been questioned. The paper presents the first comprehensive study on committee peer review for the selection of doctoral (Ph.D.) and post-doctoral research fellowship recipients. We analysed the selection procedure followed by the Boehringer Ingelheim Fonds (B.I.F.), a foundation for the promotion of basic research in biomedicine, with regard to the reliability, fairness and predictive validity of the procedure - the three quality criteria for professional evaluations. We analysed a total of 2,697 applications, 1,954 for doctoral and 743 for post-doctoral fellowships. In 76% of the cases, the fellowship award decision was characterized by agreement between reviewers. Similar figures for reliability have been reported for the grant selection procedures of other major funding agencies. With regard to fairness, we analysed whether potential sources of bias, i.e., gender, nationality, major field of study and institutional affiliation, could have influenced decisions made by the B.I.F. Board of Trustees. For post-doctoral fellowship applications, no statistically significant influence of any of these variables could be observed. For doctoral fellowship applications, we found evidence of an institutional, major field of study and gender bias, but not of a nationality bias. The most important aspect of our study was to investigate the predictive validity of the procedure, i.e., whether the foundation achieves its aim to select as fellowship recipients the best junior scientists. Our bibliometric analysis showed that this is indeed the case and that the selection procedure is thus highly valid: research articles by B.I.F. fellows are cited considerably more often than the “average' paper (average citation rate) published in the journal sets corresponding to the fields “Multidisciplinary', “Molecular Biology & Genetics', and “Biology & Biochemistry' in Essential Science Indicators (ESI) from the Institute for Scientific Information (ISI, Philadelphia, Pennsylvania, USA). Most of the fellows publish within these field

    The validity of staff editors' initial evaluations of manuscripts: a case study of Angewandte Chemie International Edition

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    This paper investigates the extent to which staff editors' evaluations of submitted manuscriptsā€”that is, internal evaluations carried out before external peer reviewingā€”are valid. To answer this question we utilized data on the manuscript reviewing process at the journal Angewandte Chemie International Edition. The results of this study indicate that the initial internal evaluations are valid. Further, it appears that external review is indispensable for the decision on the publication worthiness of manuscripts: (1) For the majority of submitted manuscripts, staff editors are uncertain about publication worthiness; (2) there is a statistically significant proportional difference in "Rejectionā€ between the editors' initial evaluation and the final editorial decision (after peer review); (3) three-quarters of the manuscripts that were rated negatively at the initial internal evaluation but accepted for publication after the peer review had far above-average citation count

    Does the h -index for ranking of scientists really work?

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    Summary: Hirsch (2005) has proposed the h-index as a single-number criterion to evaluate the scientific output of a researcher (Ball, 2005): A scientist has index h if h of his/her Np papers have at least h citations each, and the other (Np āˆ’ h) papers have fewer than h citations each. In a study on committee peer review (Bornmann & Daniel, 2005) we found that on average the h-index for successful applicants for post-doctoral research fellowships was consistently higher than for non-successful applicant
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