1,035 research outputs found

    The WiFeS S7 AGN survey: Current status and recent results on NGC 6300

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    The Siding Spring Southern Seyfert Spectroscopic Snapshot Survey (S7) is a targeted survey probing the narrow-line regions (NLRs) of a representative sample of ~140 nearby (z<0.02) Seyfert galaxies by means of optical integral field spectroscopy. The survey is based on a homogeneous data set observed using the Wide Field Spectrograph WiFeS. The data provide a 25x38 arcsec2^2 field-of-view around the galaxy centre at typically ~1.5 arcsec spatial resolution and cover a wavelength range between ~3400 - 7100 A˚\AA at spectral resolutions of ~100 km s−1^{-1} and ~50 km s−1^{-1} in the blue and red parts, respectively. The survey is primarily designed to study gas excitation and star formation around AGN, with a special focus on the shape of the AGN ionising continuum, the interaction between radio jets and the NLR gas, and the nature of nuclear LINER emission. We provide an overview of the current status of S7-based results and present new results for NGC 6300.Comment: 5 pages, 1 figure, Refereed Proceeding of the "The Universe of Digital Sky Surveys" conference held at the INAF - Observatory of Capodimonte, Naples, on 25th-28th november 2014, to be published on Astrophysics and Space Science Proceedings, edited by Longo, Napolitano, Marconi, Paolillo, Iodic

    Mixed mode data clustering: an approach based on tectrachoric correlations

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    In this paper we face the problem of clustering mixedmode data by assuming that the observed binary variables aregenerated from latent continuous variables. We perform a principalcomponents analysis on the matrix of tetrachoric correlations and wethen estimate the scores of each latent variable and construct adata matrix with continuous variables to be used in fully Guassianmixture models or in the k-means cluster analysis. The calculationof the expected a posteriori (EAP) estimates may proceed by simplyconsidering a limited number of quadrature points. Results on asimulation study and on a real data set are reported

    Infrared-faint radio sources: A new population of high-redshift radio galaxies

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    We present a sample of 1317 Infrared-faint radio sources (IFRSs) that, for the first time, are reliably detected in the infrared, generated by cross-correlating the Wide-field Infrared Survey Explorer (WISE) all-sky survey with major radio surveys. Our IFRSs are brighter in both radio and infrared than the first-generation IFRSs that were undetected in the infrared by the Spitzer Space Telescope. We present the first spectroscopic redshifts of IFRSs, and find that all but one of the IFRSs with spectroscopy have z > 2. We also report the first X-ray counterparts of IFRSs, and present an analysis of radio spectra and polarization, and show that they include gigahertz peaked-spectrum, compact steep-spectrum and ultra-steep-spectrum sources. These results, together with their WISE infrared colours and radio morphologies, imply that our sample of IFRSs represents a population of radio-loud active galactic nuclei at z > 2. We conclude that our sample consists of lower redshift counterparts of the extreme first-generation IFRSs, suggesting that the fainter IFRSs are at even higher redshift

    Dual Routes from Social Identity to Collective Opposition against Criminal Organisations: Intracultural Appropriation Theory and the roles of Honour Codes and Social Change Beliefs

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    Italian criminal organisations (COs) are a serious global threat. Intracultural Appropriation Theory (ICAT) holds that such groups exploit cultural codes of masculinity and honour to legitimise and lower resistance to their actions. Such codes are an important feature of Southern Italian group membership. A large survey (N = 1173) investigated the role of two previously under-examined facets of honour cultures – personal concerns for reputation, and female honour ideology. In addition, drawing on social identity theory, and testing a dual route hypothesis, this research investigated the role of beliefs about the necessity of social change in the articulation between identification, honour, and collective action intentions. Consistent with ICAT, and with previous research, male-honour related values uniquely predicted collective action intentions against criminal organisations. In addition, consistent with the dual route hypothesis: a) regional identification positively predicted social change beliefs which in turn explained stronger intentions to oppose COs collectively, and, b) regional identification was also positively associated with masculine honour which in turn predicted weaker intentions to oppose COs. The evidence supports the idea that social identity can have opposing effects on collective action in the same context, depending on which beliefs are mobilised

    An Adaptive Interacting Wang-Landau Algorithm for Automatic Density Exploration

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    While statisticians are well-accustomed to performing exploratory analysis in the modeling stage of an analysis, the notion of conducting preliminary general-purpose exploratory analysis in the Monte Carlo stage (or more generally, the model-fitting stage) of an analysis is an area which we feel deserves much further attention. Towards this aim, this paper proposes a general-purpose algorithm for automatic density exploration. The proposed exploration algorithm combines and expands upon components from various adaptive Markov chain Monte Carlo methods, with the Wang-Landau algorithm at its heart. Additionally, the algorithm is run on interacting parallel chains -- a feature which both decreases computational cost as well as stabilizes the algorithm, improving its ability to explore the density. Performance is studied in several applications. Through a Bayesian variable selection example, the authors demonstrate the convergence gains obtained with interacting chains. The ability of the algorithm's adaptive proposal to induce mode-jumping is illustrated through a trimodal density and a Bayesian mixture modeling application. Lastly, through a 2D Ising model, the authors demonstrate the ability of the algorithm to overcome the high correlations encountered in spatial models.Comment: 33 pages, 20 figures (the supplementary materials are included as appendices

    Cooperation, Norms, and Revolutions: A Unified Game-Theoretical Approach

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    Cooperation is of utmost importance to society as a whole, but is often challenged by individual self-interests. While game theory has studied this problem extensively, there is little work on interactions within and across groups with different preferences or beliefs. Yet, people from different social or cultural backgrounds often meet and interact. This can yield conflict, since behavior that is considered cooperative by one population might be perceived as non-cooperative from the viewpoint of another. To understand the dynamics and outcome of the competitive interactions within and between groups, we study game-dynamical replicator equations for multiple populations with incompatible interests and different power (be this due to different population sizes, material resources, social capital, or other factors). These equations allow us to address various important questions: For example, can cooperation in the prisoner's dilemma be promoted, when two interacting groups have different preferences? Under what conditions can costly punishment, or other mechanisms, foster the evolution of norms? When does cooperation fail, leading to antagonistic behavior, conflict, or even revolutions? And what incentives are needed to reach peaceful agreements between groups with conflicting interests? Our detailed quantitative analysis reveals a large variety of interesting results, which are relevant for society, law and economics, and have implications for the evolution of language and culture as well
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