On the fine structure of the quiet solar \Ca II K atmosphere

We investigate the morphological, dynamical, and evolutionary properties of the internetwork and network fine structure of the quiet sun at disk centre. The analysis is based on a $\sim$6 h time sequence of narrow-band filtergrams centred on the inner-wing \Ca II K$_{\rm 2v}$ reversal at 393.3 nm. The results for the internetwork are related to predictions derived from numerical simulations of the quiet sun. The average evolutionary time scale of the internetwork in our observations is 52 sec. Internetwork grains show a tendency to appear on a mesh-like pattern with a mean cell size of $\sim$4-5 arcsec. Based on this size and the spatial organisation of the mesh we speculate that this pattern is related to the existence of photospheric downdrafts as predicted by convection simulations. The image segmentation shows that typical sizes of both network and internetwork grains are in the order of 1.6 arcs.Comment: 8 pages, 9 figure

Kinematics of massive star ejecta in the Milky Way as traced by 26^26Al

Context. Massive stars form in groups and their winds and supernova explosions create superbubbles up to kpc in size. The fate of their ejecta is of vital importance for the dynamics of the interstellar medium, for chemical evolution models, and the chemical enrichment of galactic halos and the intergalactic medium. However, ejecta kinematics and the characteristic scales in space and time have not been explored in great detail beyond ~10 Ka. Aims: Through measurement of radioactive 26Al with its decay time constant at ~106 years, we aim to trace the kinematics of cumulative massive-star and supernova ejecta independent of the uncertain gas parameters over million-year time scales. Our goal is to identify the mixing time scale and the spatio-kinematics of such ejecta from the pc to kpc scale in our Milky Way. Methods: We use the SPI spectrometer on the INTEGRAL observatory and its observations along the Galactic ridge to trace the detailed line shape systematics of the 1808.63 keV gamma-ray line from 26Al decay. We determine line centroids and compare these to Doppler shift expectations from large-scale systematic rotation around the Galaxy centre, as observed in other Galactic objects. Results: We measure the radial velocities of gas traced by 26Al, averaged over the line of sight, as a function of Galactic longitude. We find substantially higher velocities than expected from Galactic rotation, the average bulk velocity being ~200 km s-1 larger than predicted from Galactic rotation. The observed radial velocity spread implies a Doppler broadening of the gamma-ray line that is consistent with our measurements of the overall line width. We can reproduce the observed characteristics with 26Al sources located along the inner spiral arms, when we add a global blow-out preference into the forward direction away from arms into the inter-arm region, as is expected when massive stars are offset towards the spiral-arm leading edge. With the known connection of superbubbles to the gaseous halo, this implies angular-momentum transfer in the disk-halo system and consequently also radial gas flows. The structure of the interstellar gas above the disk affects how ionizing radiation may escape and ionize intergalactic gas.Peer reviewe

Effects of Interstellar Dust Scattering on the X-ray Eclipses of the LMXB AX J1745.6-2901 in the Galactic Center

AX J1745.6-2901 is an eclipsing low mass X-ray binary (LMXB) in the Galactic Centre (GC). It shows significant X-ray excess emission during the eclipse phase, and its eclipse light curve shows an asymmetric shape. We use archival XMM-Newton and Chandra observations to study the origin of these peculiar X-ray eclipsing phenomena. We find that the shape of the observed X-ray eclipse light curves depends on both photon energy and the shape of the source extraction region, and also shows differences between the two instruments. By performing detailed simulations for the time-dependent X-ray dust scattering halo, as well as directly modelling the observed eclipse and non-eclipse halo profiles of AX J1745.6-2901, we obtained solid evidence that its peculiar eclipse phenomena are indeed caused by the X-ray dust scattering in multiple foreground dust layers along the line-of-sight (LOS). The apparent dependence on the instruments is caused by different instrumental point-spread-functions. Our results can be used to assess the influence of dust scattering in other eclipsing X-ray sources, and raise the importance of considering the timing effects of dust scattering halo when studying the variability of other X-ray sources in the GC, such as Sgr A*. Moreover, our study of halo eclipse reinforces the existence of a dust layer local to AX J1745.6-2901 as reported by Jin et al. (2017), as well as identifying another dust layer within a few hundred parsecs to Earth, containing up to several tens of percent LOS dust, which is likely to be associated with the molecular clouds in the Solar neighbourhood. The remaining LOS dust is likely to be associated with the molecular clouds located in the Galactic disk in-between.Comment: 25 pages, 18 figures, 5 tables, accepted by MNRA

Exit, Voice, and Cyclicality: A Micro-Logic of Voting Behaviour in European Parliament Elections

Unlike other classics of political economy, “Exit, Voice, and Loyalty” (EVL) has not sparked many innovations in the field of electoral studies. This paper aims to demonstrate that scholars miss out on a powerful theory of political behaviour by leaving Hirschman’s ideas to other disciplines. To change this, I resolve several theoretical complications that have hampered the application of EVL to democratic elections. On this basis, I construct a model of voting behaviour through the electoral cycle to explain typical “second-order” effects in elections to the European Parliament (EP). Building on the parameters of EVL allows to unite such diverse phenomena as anti-government swings, declining turnout, protest voting, conversion and alienation in one theoretical framework. Testing the model with survey data from the European Election Studies of 1999 and 2004 reveals novel insights into the dynamics at work in EP elections. The role of strategic voting in the form of voice appears to be limited. Instead, processes of de- and realignment in the form of exit dominate a picture of EP elections that undermines the widespread conception of second-order irrelevance

Detecting Sunyaev-Zel'dovich clusters with PLANCK: III. Properties of the expected SZ-cluster sample

The PLANCK-mission is the most sensitive all-sky submillimetric mission currently being planned and prepared. Special emphasis is given to the observation of clusters of galaxies by their thermal Sunyaev-Zel'dovich (SZ) effect. In this work, the results of a simulation are presented that combines all-sky maps of the thermal and kinetic SZ-effect with cosmic microwave background (CMB) fluctuations, Galactic foregrounds (synchrotron emission, thermal emission from dust, free-free emission and rotational transitions of carbon monoxide molecules) and sub-millimetric emission from planets and asteroids of the Solar System. Observational issues, such as PLANCKs beam shapes, frequency response and spatially non-uniform instrumental noise have been incorporated. Matched and scale-adaptive multi-frequency filtering schemes have been extended to spherical coordinates and are now applied to the data sets in order to isolate and amplify the weak thermal SZ-signal. The properties of the resulting SZ-cluster sample are characterised in detail: Apart from the number of clusters as a function of cluster parameters such as redshift z and total mass M, the distribution n(sigma)d sigma of the detection significance sigma, the number of detectable clusters in relation to the model cluster parameters entering the filter construction, the position accuracy of an SZ-detection and the cluster number density as a function of ecliptic latitude beta is examined.Comment: 14 pages, 16 figures, 13 tables, submitted to MNRAS, 16.Feb.200

Exploring Enterprise Life Cycle: Differences in Informal and Formal Institutional Measures of Business Ethics Implementation

Since science recognizes the fact that an enterprise passes through different life cycle stages, and that life cycle stages differ in terms of management systems, formal structures, control systems, documentation of transactions, and number of procedural hurdles, our main research problem was focused on differences in informal and formal institutional measures of business ethics implementation. The case study research methodology was applied to explore the differences of informal and formal institutional measures of business ethics implementation at different stages of enterprise life cycle. The pre-designed questionnaire was used in conducting face-to-face interviews with 40 managers who were in most cases also owners of the studied enterprises.

Deployment and performance evaluation of a SNAP-based resource broker on the White Rose grid

Resource brokering is an essential component in building effective Grid systems. The aim of this paper is to evaluate the performance of a SNAP (Service Negotiation and Acquisition Protocol) based resource broker on a large distributed Grid infrastructure, the White Rose Grid. The broker uses a three-phase commit protocol to reserve resources on demand, as the traditional advance reservation facilities cannot cater for such needs due to the prior time that it requires to schedule reservations. Experiments are designed and carried out on the White Rose Grid. The experimental results show that the inclusion of the three-phase commit protocol provides a performance enhancement on a large distributed Grid Infrastructure, in terms of the time taken from submission of user requirements until a job begins execution. The results support those previously obtained through the use of mathematical modelling and simulation. The broker is a viable contender for use in future Grid resource brokering implementations