Parallel tracks as quasi-steady states for the magnetic boundary layers in neutron-star low-mass X-ray binaries

The neutron stars in low-mass X-ray binaries (LMXBs) are usually thought to be weakly magnetized objects accreting matter from their low-mass companions in the form of a disk. Albeit weak as compared to those in young neutron-star systems, the neutron-star magnetospheres in LMXBs can play an important role in determining the correlations between spectral and temporal properties. Parallel tracks appearing in the plane of kilohertz (kHz) quasi-periodic oscillation (QPO) frequency versus X-ray flux can be used as a tool to study the magnetosphere-disk interaction in neutron-star LMXBs. For dynamically important weak fields, the formation of a non-Keplerian magnetic boundary layer at the innermost disk truncated near the surface of the neutron star is highly likely. Such a boundary region may harbor oscillatory modes of frequencies in the kHz range. We generate parallel tracks using the boundary region model of kHz QPOs. We also present the direct application of our model to the reproduction of the observed parallel tracks of individual sources such as 4U 1608--52, 4U 1636--53, and Aql X-1. We reveal how the radial width of the boundary layer must vary in the long-term flux evolution of each source to regenerate the parallel tracks. The run of the radial width looks similar for different sources and can be fitted by a generic model function describing the average steady behavior of the boundary region in the long term. The parallel tracks then correspond to the possible quasi-steady states the source can occupy around the average trend.Comment: 16 pages, 15 figures, accepted for publication in Ap

EU Integration and the Change of Spatial Organization in Turkey

After 1980, economic agenda changed and international trade and integration to global and regional systems gained more importance in Turkey, like in many countries. As a candidate of the EU Turkey as well has experienced a change in the spatial organization. It has been shown by many other studies that integration process leads to a change in the industrial structure and spatial organization. The effect of the removal or lowering of trade barriers and its effects on the industrial location has been widely investigated in the New Economic Geography literature. These effects are of great importance for some essential grounds of European Integration, such as a balanced regional development and decreasing inequalities among regions to increase overall competitiveness, since they may cause an increase in the regional disparities and conflict with main targets of integration. This paper analyses the change of spatial organization in Turkey through the integration process to the EU by using location quotient, dissimilarity index and some other indicators and tries to show whether if spatial organization changed in favour of existing centres or if new centres have emerged.

Regional Integration in the Black Sea Region: the Case of Two Sisters, Istanbul and Odessa

The political change in the 1980’es and 1990’es in the Black Sea Region has introduced many questions regarding its future as the region faces massive problems like conflicts on territory, drop of production levels in the 1990’es and related poverty, and last but not the least, environmental problems. The size of the region also blurs the picture. However, briefly there are three major influences that mark the future development of the region: globalization, regionalization and Euro-Asian integration. We propose that under these three influences, a new global integration zone, consisting of multiple networks between cities of the Black Sea Region is emerging. Our proposition that a new global integration zone is emerging within the Black Sea Region depends on three assumptions: Our first assumption is that neo-liberal globalization and regionalization (and particularly Euro-Asian integration) lead to development of similar political changes in the region. Our second assumption is that neo-liberal globalization and regionalization lead to development of similar spatial socio-economic developments within the Black Sea Region which brings some cities to the fore to gain power in the national and global organization of production. Our third assumption is that there is increasing trans-national integration between subject cities. Emergence of such a zone is perhaps most important for policy makers at the local level who have to face either positive or negative on-site effects of globalization and regionalization. Increasing socio-economic inequalities, excessive agglomeration of economic activities and population, diversification of population and increasing complexity of problems cripple traditional city management and planning practices in these countries which have a strong central planning and administration background. Due to practical reasons, we limit our study to integration of two sub-national regions, the province of Istanbul, and the province of Odessa which are also sister cities. Province of Istanbul may be recalled as Greater Istanbul, or Istanbul Metropolitan City since at 2004 due to change in the administrative legislation. Province of Odessa includes the city of Odessa as well as other cities within the province. We may conclude that there is progressive convergence in the political grounds between Turkey-Ukraine and Istanbul-Odessa, mainly in the framework of the global structures that are predominantly part of the Euro-Atlantic supra-structure. Though there is not much evidence of similarity in spatial development of Istanbul and Odessa, particularly due to political inclarity and problems of administrative decentralization in Ukraine, there is evidence of economic and social integration, between Turkey-Ukraine and Istanbul-Odessa, which experiences slow development, and negative side effects like informal activities. As a conclusion we may argue that integration of two regions might heavily depend on the Ukrainian foreign and domestic policies, and the decisions of supra-national structures like the World Trade Organization and EU. We may expect a progress in economic integration by the removal of trade barriers, where Istanbul and Odessa would be direct beneficiaries as both production and transfer centres. Further administrative decentralization in Ukraine might lead to a re-population in Odessa Region, as happened in Istanbul after the 1980 period.

Auctions with Anticipated Regret

This paper demonstrates theoretically and experimentally that in first price auctions, overbidding with respect to risk neutral Nash equilibrium might be driven from anticipated loser regret (felt when bidders lose at an affordable price). Different information structures are created to elicit regret: bidders know they will learn the winning bid if they lose (loser regret condition); or the second highest bid if they win (winner regret condition); or no information regarding the other bids. Bidders only in loser regret condition anticipated regret and significantly overbid; in the other conditions bidders did not anticipate regret and hence did not overbid.overbidding, first price auction, anticipated regret

The Impact of Corporate Restructuring and Downsizing on the Managerial Careers of Minorities and Women: Lessons Learned from Nine Companies

Glass Ceiling ReportGlassCeilingBackground6ImpactofCorporateDownsizing.pdf: 1346 downloads, before Oct. 1, 2020.0-Pages_from_ImpactofCorporateRestructuringDownsizing.pdf: 87 downloads, before Oct. 1, 2020.1-Appendixfrom_ImpactofCorporateRestructuringDownsizing.pdf: 2958 downloads, before Oct. 1, 2020

On the high-frequency quasi-periodic oscillations from black holes

We apply the global mode analysis, which has been recently developed for the modeling of kHz quasi-periodic oscillations (QPOs) from neutron stars, to the inner region of an accretion disk around a rotating black hole. Within a pseudo-Newtonian approach that keeps the ratio of the radial epicyclic frequency $\kappa$ to the orbital frequency $\Omega$ the same as the corresponding ratio for a Kerr black hole we determine the innermost disk region where the hydrodynamic modes grow in amplitude. We find that the radiation flux emerging from the inner disk has the highest values within the same region. Using the flux weighted averages of the frequency bands over this region we identify the growing modes with highest frequency branches $\Omega +\kappa$ and $\Omega$ to be the plausible candidates for the high-frequency QPO pairs observed in black hole systems. The observed frequency ratio around 1.5 can therefore be understood naturally in terms of the global free oscillations in the innermost region of a viscous accretion disk around a black hole without invoking a particular resonance to produce black hole QPOs. Although the frequency ratio $/$ is found to be not sensitive to the black hole's spin which is good for explaining the high-frequency QPOs it may work as a limited diagnostic of the spin parameter to distinguish black holes with very large spin from the slowly rotating ones. Within our model we estimate the frequency ratio of a high-frequency QPO pair to be greater than 1.5 if the black hole is a slow rotator. For fast rotating black holes, we expect the same ratio to be less than 1.5.Comment: 11 pages, 11 figures, already published in The Astrophysical Journa