On the Column Density of AGN Outflows: the Case of NGC 5548

We re-analyze the HST high resolution spectroscopic data of the intrinsic absorber in NGC 5548 and find that the C IV absorption column density is at least four times larger than previously determined. This increase arises from accounting for the kinematical nature of the absorber and from our conclusion that the outflow does not cover the narrow emission line region in this object. The improved column density determination begins to bridge the gap between the high column densities measured in the X-ray and the low ones previously inferred from the UV lines. Combined with our findings for outflows in high luminosity quasars these results suggest that traditional techniques for measuring column densities: equivalent width, curve-of-growth and Gaussian modeling, are of limited value when applied to absorption associated with AGN outflows.Comment: Published ApJ version (566, 699), including a new figure with FUSE data and a useful algebraic expression for the optical depth solutio

Monitoring in beeld: een studie naar de doorwerking van monitors in interbestuurlijke relaties

Monitoring in the Dutch public sector An increasing stream of monitoring activities has entered the public sector. A lot of different monitors have been implemented in the Netherlands, like the police monitor, drugs monitor, integration monitor and the emancipation monitor. Although monitoring of policy processes is quite prevalent in the public sector, monitoring still remains an unexplored scientific theme, while most of the scientific attention is restricted to performance systems. In the current mode of monitoring is often approached in a rational way. Within the rational approach monitoring is seen as an objective search for facts in order to improve policy. The aim of this study however, is to widen this narrow focus and include two other perspectives as well, namely a political and cultural approach of monitoring. These three perspectives are not mutually exclusive. One of the assumptions of this study is that monitoring activities have impacts on intergovernmental relationships, this because monitors are used on different governmental levels. The impacts of monitors on intergovernmental relationships have not been studied as of yet. This is surprising, because in policy documents monitoring is connected with intergovernmental relationships. Research questions The main research question is formulated as followed: what are the impacts of monitors on intergovernmental relationships? This main question is divided into seven research questions

Integrale aanpak tegen emissie van bolontsmettingsmiddelen

Verschillende bolontsmettingsmiddelen worden in te hoge concentraties in het oppervlaktewater gevonden. Telen met toekomst ontwikkelde samen met een groot aantal toeleveranciers en adviseurs een integrale aanpak om de problemen op te lossen. Veel is al bereikt, maar er is ook nog veel te doen, zoals het verbeteren van inzicht in emissieroutes

Onderzoek Teelt de grond uit Bloembollen in 2011

In 2011 wordt het tweede jaar met proeven uitgevoerd in het kader van het project Teelt de grond uit. Op drie locaties wordt nagegaan welke alternatieve mogelijkheden er zijn voor de bloembollenteelt die niet afhankelijk is van teelt in de vollegrond. In dit artikel komen de plannen voor 2011 aan de orde

Accretion disk reversal and the spin-up/spin-down of accreting pulsars

We numerically investigate the hydrodynamics of accretion disk reversal and relate our findings to the observed spin-rate changes in the accreting X-ray pulsar GX~1+4. In this system, which accretes from a slow wind, the accretion disk contains two dynamically distinct regions. In the inner part viscous forces are dominant and disk evolution occurs on a viscous timescale. In the outer part dynamical mixing of material with opposite angular momentum is more important, and the externally imposed angular momentum reversal timescale governs the flow. In this outer region the disk is split into concentric rings of material with opposite senses of rotation that do not mix completely but instead remain distinct, with a clear gap between them. We thus predict that torque reversals resulting from accretion disk reversals will be accompanied by minima in accretion luminosity.Comment: 13 pages, 7 figures, accepted for publication in Ap