European Principles Governing National Administrative Proceedings

It is critical that the process of developing general principles of Community administrative law continue, notwithstanding the marked diversity of supranational administrative proceedings. Because Community law has traditionally been focused on activities relevant to the common market, an asymmetry between the regulation of market-related administrative proceedings and other types of administrative proceedings has developed

Structural determination and electronic properties of 4d perovskite SrPdO3

The structure and ground state electronic structure of the recently synthesized SrPdO$_3$ perovskite [A. Galal {\em et al.}, J. Power Sources, {\bf 195}, 3806 (2010)] have been studied by means of screened hybrid functional and the GW approximation with the inclusion of electron-hole interaction within the test-charge/test-charge scheme. By conducting a structural search based on lattice dynamics and group theoretical method we identify the orthorhombic phase with $P_{nma}$ space group as the most stable crystal structure. The phase transition from the ideal cubic perovskite structure to the $P_{nma}$ one is explained in terms of the simultaneous stabilization of the antiferrodistortive phonon modes $R_4^+$ and $M_3^+$. Our results indicate that SrPdO$_3$ exhibits an insulating ground state, substantiated by a GW$_0$ gap of about 1.1 eV. Spin polarized calculations suggests that SrPdO$_3$ adopts a low spin state ($t_{2g}^{\uparrow\downarrow\uparrow\downarrow\uparrow\downarrow}e_g^0$), and is expected to exhibit spin excitations and spin state crossovers at finite temperature, analogous to the case of 3$d$ isoelectronic LaCoO$_3$. This would provide a new playground for the study of spin state transitions in 4$d$ oxides and new opportunity to design multifunctional materials based on 4$d$ $P_{nma}$ building block

The Frequency of Kozai–Lidov Disc Oscillation Driven Giant Outbursts in Be/X-Ray Binaries

Giant outbursts of Be/X-ray binaries may occur when a Be-star disc undergoes strong eccentricity growth due to the Kozai–Lidov (KL) mechanism. The KL effect acts on a disc that is highly inclined to the binary orbital plane provided that the disc aspect ratio is sufficiently small. The eccentric disc overflows its Roche lobe and material flows from the Be star disc over to the companion neutron star causing X-ray activity. With N-body simulations and steady state decretion disc models we explore system parameters for which a disc in the Be/X-ray binary 4U 0115+634 is KL unstable and the resulting time-scale for the oscillations. We find good agreement between predictions of the model and the observed giant outburst time-scale provided that the disc is not completely destroyed by the outburst. This allows the outer disc to be replenished between outbursts and a sufficiently short KL oscillation time-scale. An initially eccentric disc has a shorter KL oscillation time-scale compared to an initially circular orbit disc. We suggest that the chaotic nature of the outbursts is caused by the sensitivity of the mechanism to the distribution of material within the disc. The outbursts continue provided that the Be star supplies material that is sufficiently misaligned to the binary orbital plane. We generalize our results to Be/X-ray binaries with varying orbital period and find that if the Be star disc is flared, it is more likely to be unstable to KL oscillations in a smaller orbital period binary, in agreement with observations

Type I Outbursts in Low-eccentricity Be/X-Ray Binaries

Type I outbursts in Be/X-ray binaries are usually associated with the eccentricity of the binary orbit. The neutron star accretes gas from the outer parts of the decretion disk around the Be star at each periastron passage. However, this mechanism cannot explain type I outbursts that have been observed in nearly circular orbit Be/X-ray binaries. With hydrodynamical simulations and analytic estimates we find that in a circular orbit binary, a nearly coplanar disk around the Be star can become eccentric. The extreme mass ratio of the binary leads to the presence of the 3:1 Lindblad resonance inside the Be star disk and this drives eccentricity growth. Therefore the neutron star can capture material each time it approaches the disk apastron, on a timescale up to a few percent longer than the orbital period. We have found a new application of this mechanism that is able to explain the observed type I outbursts in low-eccentricity Be/X-ray binaries

Ab initio prediction of the high-pressure phase diagram of BaBiO3

BaBiO3 is a well-known example of a 3D charge density wave (CDW) compound, in which the CDW behavior is induced by charge disproportionation at the Bi site. At ambient pressure, this compound is a charge-ordered insulator, but little is known about its high-pressure behavior. In this work, we study from first principles the high-pressure phase diagram of BaBiO3 using phonon mode analysis and evolutionary crystal structure prediction. We show that charge disproportionation is very robust in this compound and persists up to 100 GPa. This causes the system to remain insulating up to the highest pressure we studied