The radio source B 1834+620: A double-double radio galaxy with interesting properties

We present a study of the peculiar radio galaxy B 1834+620. It is characterised by the presence of a 420-kpc large edge-brightened radio source which is situated within, and well aligned with, a larger (1.66 Mpc) radio source. Both sources apparently originate in the same host galaxy, which has a R_s-magnitude of 19.7 and a redshift of 0.5194, as determined from the strong emission-lines in the spectrum. We have determined the rotation measures towards this source, as well as the radio spectral energy distribution of its components. The radio spectrum of the large outer source is steeper than that of the smaller inner source. The radio core has a spectrum that peaks at a frequency of a few GHz. The rotation measures towards the four main components are quite similar, within $\sim\!2$ rad m$^{-2}$ of 58 rad m$^{-2}$. They are probably largely galactic in origin. We have used the presence of a bright hotspot in the northern outer lobe to constrain the advance velocity of the inner radio lobes to the range between 0.19c and 0.29c, depending on the orientation of the source. This corresponds to an age of this structure in the range between 2.6 and 5.8 Myr. We estimate a density of the ambient medium of the inner lobes of \la 1.6 \times 10^{-30} gr\,cm$^{-3}$ (particle density \la 8 \times 10^{-7} cm$^{-3}$). A low ambient density is further supported by the discrepancy between the large optical emission-line luminosity of the host galaxy and the relatively low radio power of the inner lobes.Comment: Accepted for publication in MNRA

Exploring differences in social disclosures internationally: A stakeholder perspective

Country of origin is considered to be an important determinant of the level and type of corporate social disclosure. In this paper, we use stakeholder theory to explain differ- ences in social disclosure among countries. We argue that the manner in which the role of a corporation and its stakeholders is defined in a society will affect the extent and quality of corporate social disclosure (CSD) in annual reports. Our findings based on a content analysis of 1998 and 1999 annual reports for 32 Norwegian/Danish companies and 26 US companies in the electric power generation industry, lend support to the stakeholder explanation for observed international differences in CSD

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Does the adoption of IFRS affect corporate social disclosure in annual reports?

In this exploratory study we investigate the impact of the implementation of IFRS on corporate social disclosures (CSD) within the context of stakeholder theory. We measure the level of CSD in annual reports using a disclosure instrument based on the United Nations Conference on Trade and Development report “Guidance on Corporate Responsibility Indicators in Annual Reports”. We find that IFRS adoption had a differential effect on CSD based on a firm\u27s institutional setting i.e., the stakeholder–management relationship prevalent in their institutional environment. Firms in the stakeholder countries did not have a significant change in the level of CSD following the mandatory adoption of IFRS while firms from the shareholder countries experienced a significant increase over the same period resulting in shareholder countries providing an overall higher level of CSD after IFRS adoption than stakeholder countries. These findings suggest that firms\u27 reactions to the requirements of IFRS and the stakeholder pressure to provide additional CSD are influenced by institutional environment. Further, our results provide support for the use of stakeholder theory to predict the level of CSD

Synchrotron Radiation Techniques and their Application to Actinide Materials

Research on actinide materials, both basic and applied, has been greatly advanced by the general techniques available from high-intensity photon beams from x-ray synchrotron sources. The most important single reason is that such x-ray sources can work with minute (e.g., microgram) samples, and at this level, the radioactive hazards of actinides are much reduced. We start by discussing the form and encapsulation procedures used for different techniques, then discuss the basic theory for interpreting the results. By reviewing a selection of x-ray diffraction (XRD), resonant elastic x-ray scattering (REXS), x-ray magnetic circular dichroism (XMCD), resonant and non-resonant inelastic scattering (RIXS, NIXS), dispersive inelastic x-ray scattering (IXS), and conventional and resonant photoemission experiments, we demonstrate the potential of synchrotron radiation techniques in studying lattice and electronic structure, hybridization effects, multipolar order, and lattice dynamics in actinide materials.Comment: To be published in Reviews of Modern Physics; 57 pages, 36 figures, 475 reference

Inferring Rn-222 soil fluxes from ambient Rn-222 activity and eddy covariance measurements of CO2

We present a new methodology, which we call Single Pair of Observations Technique with Eddy Covariance (SPOT-EC), to estimate regional-scale surface fluxes of 222Rn from tower-based observations of 222Rn activity concentration, CO2 mole fractions and direct CO2 flux measurements from eddy covariance. For specific events, the regional (222Rn) surface flux is calculated from short-term changes in ambient (222Rn) activity concentration scaled by the ratio of the mean CO2 surface flux for the specific event to the change in its observed mole fraction. The resulting 222Rn surface emissions are integrated in time (between the moment of observation and the last prior background levels) and space (i.e. over the footprint of the observations). The measurement uncertainty obtained is about ±15 % for diurnal events and about ±10 % for longer-term (e.g. seasonal or annual) means. The method does not provide continuous observations, but reliable daily averages can be obtained. We applied our method to in situ observations from two sites in the Netherlands: Cabauw station (CBW) and Lutjewad station (LUT). For LUT, which is an intensive agricultural site, we estimated a mean 222Rn surface flux of (0.29 ± 0.02) atoms cm−2 s−1 with values  > 0.5 atoms cm−2 s−1 to the south and south-east. For CBW we estimated a mean 222Rn surface flux of (0.63 ± 0.04) atoms cm−2 s−1. The highest values were observed to the south-west, where the soil type is mainly river clay. For both stations good agreement was found between our results and those from measurements with soil chambers and two recently published 222Rn soil flux maps for Europe. At both sites, large spatial and temporal variability of 222Rn surface fluxes were observed which would be impractical to measure with a soil chamber. SPOT-EC, therefore, offers an important new tool for estimating regional-scale 222Rn surface fluxes. Practical applications furthermore include calibration of process-based 222Rn soil flux models, validation of atmospheric transport models and performing regional-scale inversions, e.g. of greenhouse gases via the SPOT 222Rn-tracer method

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Uitgebreide tekst van het afscheidscollege, uitgesproken op vrijdag 2 november 2001