Germany's preferences on the freedom of movement provisions of the Ankara Agreement: the Wirtschaftswunder and opportunity and effort of Turkish diplomacy

Why did Germany support provisions on freedom of movement for Turkish workers in the Association Agreement between the European Economic Community (EEC) and Turkey, which was concluded in 1963? This is puzzling given that Germany was fervently opposed to other common EU measures on legal economic migration since immigration policy was communitarized by the Amsterdam Treaty in 1999. The papers test two hypotheses. First, that the a positive economic situation induces the German government to support common EU measures as in periods of strong growth Germany has more open immigration policies and there is a positive relationship between open national immigration policies and support for common EU measures. Second, a sending country (or a group of sending countries) needs to exert diplomatic pressure on the German government in order for it to support common EU measures on legal economic migration. For this to be successful there need to be two conditions in place, the sending country must have the opportunity to exert influence, due to strong historical ties with Germany or being important for geo-political reasons, and frame the need for common EU measures on legal migration in an effective manner. The hypotheses are confirmed for the case of Turkey and the Ankara Agreement and are used to assemble a theoretically eclectic and generally applicable framework able to explain Germany’s support for common EU measures on legal economic migration

Special coatings control temperature of structures

Special coatings in the form of paints that exhibit controlled ratios of sunlight absorptivity to grey-body emissivity control the temperature of structures in space flight. These finishes exhibit good resistance to ultraviolet radiation and do not discolor

Variability of black hole accretion discs: The cool, thermal disc component

We extend the model of King et al. (2004) for variability in black hole accretion discs, by taking proper account of the thermal properties of the disc. Because the degree of variability in the King et al. (2004) model depends sensitively on the ratio of disc thickness to radius, H/R, it is important to follow the time-dependence of the local disc structure as the variability proceeds. In common with previous authors, we develop a one-zone model for the local disc structure. We agree that radial heat advection plays an important role in determining the inner disc structure, and also find limit-cycle behaviour. When the stochastic magnetic dynamo model of King et al. (2004) is added to these models, we find similar variability behaviour to before. We are now better placed to put physical constraints on model parameters. In particular, we find that in order to be consistent with the low degree of variability seen in the thermal disc component of black hole binaries, we need to limit the energy density of the poloidal field that can be produced by local dynamo cells in the disc to less than a few percent of the energy density of the dynamo field within the disc itself.Comment: 18 pages, 17 figures, accepted by MNRA

Beyond Crisis Management: The Path Towards an Effective, Pro-active and Fair European Refugee Policy. Bertelsmann Study

Europe urgently needs an effective, pro-active and fair refugee policy. Short-sighted policy-making and a narrow focus on what seemed to be in the immediate national interests have led to a conglomerate of European refugee policies. These policies are clearly ineffective and resulted in a large and partially uncontrolled refugee movement to and within Europe in 2015. Refugee flows to Europe are unlikely to subside soon, as many conflicts persist and the average duration of protracted refugee situations worldwide is on the rise. In a reaction to these circumstances, the European Com-mission has proposed a number of initiatives to reform the Common European Asylum System (CEAS). Consensus is more likely on the introduction of restrictions and sanctions rather than, for example, fair distribution systems or pooling sovereignty on the EU level by establishing a strong EU Agency of Asylum. Yet, especially pro-active solutions that meet Europe’s humanitarian responsi-bilities are necessary. The paper puts forward policy-recommendations for a paradigm-shift from reactive to pro-active refugee policies. The overarching objective is to create further legal channels for refugees to seek protection in Europe. Measures include both national and EU-policies and are supposed to pave the way to a sustainable and coherent European refugee policy. The policy recommendations are clus-tered in five overarching themes: create safe passages to protection, improve national asylum processing and integration systems, establish further legal pathways for mixed migration, enable protection in the region of origin, and tackle the root causes of forced migration through a sustainable foreign, economic and trade policy. Finally, it has to be stressed that only if we can restore Europe’s political will to manage refugee flows together, there will be sustainable solutions in sight. Regular dialogue taking into account the different resources and histories of the countries are the way forward. If member states can incrementally alight their different national policies, a comprehensive European refugee policy may follow. Given the current political differences amongst member states, this will be a lengthy process – but certainly worth the effort

Birth of massive black hole binaries

If massive black holes (BHs) are ubiquitous in galaxies and galaxies experience multiple mergers during their cosmic assembly, then BH binaries should be common albeit temporary features of most galactic bulges. Observationally, the paucity of active BH pairs points toward binary lifetimes far shorter than the Hubble time, indicating rapid inspiral of the BHs down to the domain where gravitational waves lead to their coalescence. Here, we review a series of studies on the dynamics of massive BHs in gas-rich galaxy mergers that underscore the vital role played by a cool, gaseous component in promoting the rapid formation of the BH binary. The BH binary is found to reside at the center of a massive self-gravitating nuclear disc resulting from the collision of the two gaseous discs present in the mother galaxies. Hardening by gravitational torques against gas in this grand disc is found to continue down to sub-parsec scales. The eccentricity decreases with time to zero and when the binary is circular, accretion sets in around the two BHs. When this occurs, each BH is endowed with it own small-size (< 0.01 pc) accretion disc comprising a few percent of the BH mass. Double AGN activity is expected to occur on an estimated timescale of < 1 Myr. The double nuclear point-like sources that may appear have typical separation of < 10 pc, and are likely to be embedded in the still ongoing starburst. We note that a potential threat of binary stalling, in a gaseous environment, may come from radiation and/or mechanical energy injections by the BHs. Only short-lived or sub-Eddington accretion episodes can guarantee the persistence of a dense cool gas structure around the binary necessary for continuing BH inspiral.Comment: To appear in "2007 STScI Spring Symposium: Black Holes", eds. M. Livio & A. M. Koekemoer, Cambridge University Press, 25 pages, 12 figure

A physical model for downward burning

Elementary physical model for flammable materials combustion emphasizing downward burnin

Systematic search for high-energy gamma-ray emission from bow shocks of runaway stars

Context. It has been suggested that the bow shocks of runaway stars are sources of high-energy gamma rays (E > 100 MeV). Theoretical models predicting high-energy gamma-ray emission from these sources were followed by the first detection of non-thermal radio emission from the bow shock of BD+43^\deg 3654 and non-thermal X-ray emission from the bow shock of AE Aurigae. Aims. We perform the first systematic search for MeV and GeV emission from 27 bow shocks of runaway stars using data collected by the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope (Fermi). Methods. We analysed 57 months of Fermi-LAT data at the positions of 27 bow shocks of runaway stars extracted from the Extensive stellar BOw Shock Survey catalogue (E-BOSS). A likelihood analysis was performed to search for gamma-ray emission that is not compatible with diffuse background or emission from neighbouring sources and that could be associated with the bow shocks. Results. None of the bow shock candidates is detected significantly in the Fermi-LAT energy range. We therefore present upper limits on the high-energy emission in the energy range from 100 MeV to 300 GeV for 27 bow shocks of runaway stars in four energy bands. For the three cases where models of the high-energy emission are published we compare our upper limits to the modelled spectra. Our limits exclude the model predictions for Zeta Ophiuchi by a factor $\approx$ 5.Comment: 5 pages, 5 figures, 1 table, accepted by A&