Dynamics of a self--gravitating magnetized source

We consider a magnetized degenerate gas of fermions as the matter source of a homogeneous but anisotropic Bianchi I spacetime with a Kasner--like metric. We examine the dynamics of this system by means of a qualitative and numerical study of Einstein-Maxwell field equations which reduce to a non--linear autonomous system. For all initial conditions and combinations of free parameters the gas evolves from an initial anisotropic singularity into an asymptotic state that is completely determined by a stable attractor. Depending on the initial conditions the anisotropic singularity is of the ``cigar'' or ``plate'' types.Comment: 7 pages, 1 figur

Remarks on propagating waves in non-linear vacuum electrodynamics

Using the quadratic expansion in the photon fields of Euler-Heisemberg (EH) non-linear electrodynamics (NLED) Lagrangian model we study relevant vacuum properties in a scenario involving the propagation of a photon probe in the presence of a background constant and static magnetic field, $B_e$. We compute the gauge invariant, symmetric and conserved energy-momentum tensor (EMT) and the angular momentum tensor (AMT) for arbitrary magnetic field strength using the Hilbert method under the soft-photon approximation. We discuss how the presence of magneto-electric terms in the EH Lagrangian is a source of anisotropy and induce the non-zero trace in the EMT, the latter being connected to the non-conformal anomaly of the non-linear Lagrangian and with the non-conservation of the light cone in Minkowski space-time inducing birefringence. From the EMT we analyze some quantities of interest such as the energy density, pressures, Poynting vector, and angular momentum vector and we compare them with those obtained from the Noether method. The magnetized vacuum properties are also studied showing that a photon-effective magnetic moment can be defined for different polarization modes. The calculations are done in terms of derivatives of the two scalar invariants of electrodynamics hence, extension to other NLED Lagrangian is straightforward. We discuss further physical implications and experimental strategies to test magnetization, photon pressure and efective magnetic moment.Comment: 24 pages, 3 figure

Performance Of The High Speed Rail In Spain In The Context Of The New Regulation Framework. Evidence From The Madrid-Seville Hsr Corridor

The ambitious planned development of the high-speed rail (HSR) network in Spain requires the implementation of new sector regulations to fully achieve its objectives, namely to make the sector more competitive and to promote a more balanced and efficient transport system. For this purpose, the Spanish administration recently launched the new Rail Sector Act (39/2003), on a national regulatory framework. The planned liberalisation process foresees the end of the monopoly of the Spanish state operator RENFE, opening up passenger transport to new rail operators by 2010. On a European level, this new regulatory framework comes in line with EU’s concerns both on transport service performance and on infrastructure development. On the one hand, European regulations have focused in measures to guarantee quality of service, equal access and effective competition market rules. On the other, the relevance of the development of HSR projects in the Iberian peninsula is proved with their inclusion among the priority projects of the trans-European networks (TEN).Institute of Transport and Logistics Studies. Faculty of Economics and Business. The University of Sydne

Effect of filler nature and content on the bituminous mastic behaviour under cyclic loads

The role of the filler in asphalt mixtures is particularly important because of its influence on mastic behaviour. The filler improves the resistance properties of bitumen against the action of traffic loads and temperature. However, the filler can also adversely affect bitumen in mastics excessively brittle and stiff due to inappropriate design. For these reasons, it is interesting to investigate the effect of filler type and content on mastic composition. This paper presents results from a strain sweep test applied to bituminous mastics prepared with different filler types and contents at several temperatures. The obtained stiffness modulus and failure strain results provide information to assess the fatigue behaviour of the analysed mastics.Peer ReviewedPostprint (author's final draft