Phantom inflation and the "Big Trip"

Primordial inflation is regarded to be driven by a phantom field which is here implemented as a scalar field satisfying an equation of state $p=\omega\rho$, with $\omega<-1$. Being even aggravated by the weird properties of phantom energy, this will pose a serious problem with the exit from the inflationary phase. We argue however in favor of the speculation that a smooth exit from the phantom inflationary phase can still be tentatively recovered by considering a multiverse scenario where the primordial phantom universe would travel in time toward a future universe filled with usual radiation, before reaching the big rip. We call this transition the "big trip" and assume it to take place with the help of some form of anthropic principle which chooses our current universe as being the final destination of the time transition.Comment: 23 pages, 5 figures, LaTex, Phys. Lett. B (in press

Dynamics of magnetized relativistic tori oscillating around black holes

We present a numerical study of the dynamics of magnetized, relativistic, non-self-gravitating, axisymmetric tori orbiting in the background spacetimes of Schwarzschild and Kerr black holes. The initial models have a constant specific angular momentum and are built with a non-zero toroidal magnetic field component, for which equilibrium configurations have recently been obtained. In this work we extend our previous investigations which dealt with purely hydrodynamical thick discs, and study the dynamics of magnetized tori subject to perturbations which, for the values of the magnetic field strength considered here, trigger quasi-periodic oscillations lasting for tens of orbital periods. Overall, we have found that the dynamics of the magnetized tori analyzed is very similar to that found in the corresponding unmagnetized models. The spectral distribution of the eigenfrequencies of oscillation shows the presence of a fundamental p mode and of a series of overtones in a harmonic ratio 2:3:.... These simulations, therefore, extend the validity of the model of Rezzolla et al.(2003a) for explaining the high-frequency QPOs observed in the spectra of LMXBs containing a black-hole candidate also to the case of magnetized discs with purely toroidal magnetic field distribution. If sufficiently compact and massive, these oscillations can also lead to the emission of intense gravitational radiation which is potentially detectable for sources within the Galaxy.Comment: 10 pages,7 figures, submitted to MNRA

Business Processes and Flexibility: A Theoretical Perspective

We address the intractable problem of flexibility in business process management: how to deal with variations, unique cases and exceptions? We identify and characterise five conceptualisations of business process. We discuss the main elements and relationships, contracts, and existential and representational properties established by each conceptualisation. For each conceptualisation, we analyse how it impacts flexibility and discuss different strategies for increasing flexibility. Finally, we synthesise our findings in an integrated framework, which helps by relating different conceptualisations of business process with strategies to increase flexibility. This paper makes several conceptual and practical contributions. Considering the former, we disentangle various notions of business process, considering in particular differences between ex ante and ex post, and class and instance. We also highlight that flexibility requires integrating variety and a multi-view over the events defined by a process. Regarding contributions to practice, we propose a framework for organisations to analyse how business processes can be related to flexibility