Compound orbits break-up in constituents: an algorithm

In this paper decomposition of periodic orbits in bifurcation diagrams are derived in unidimensional dynamics system $x_{n+1}=f(x_{n};r)$, being $f$ an unimodal function. We proof a theorem which states the necessary and sufficient conditions for the break-up of compound orbits in their simpler constituents. A corollary to this theorem provides an algorithm for the computation of those orbits. This process closes the theoretical framework initiated in (Physica D, 239:1135--1146, 2010)

High--Resolution 3D Simulations of Relativistic Jets

We have performed high-resolution 3D simulations of relativistic jets with beam flow Lorentz factors up to 7, a spatial resolution of 8 cells per beam radius, and for up to 75 normalized time units to study the morphology and dynamics of 3D relativistic jets. Our simulations show that the coherent fast backflows found in axisymmetric models are not present in 3D models. We further find that when the jet is exposed to non-axisymmetric perturbations, (i) it does not display the strong perturbations found for 3D classical hydrodynamic and MHD jets (at least during the period of time covered by our simulations), and (ii) it does propagate according to the 1D estimate. Small 3D effects in the relativistic beam give rise to a lumpy distribution of apparent speeds like that observed in M87. The beam is surrounded by a boundary layer of high specific internal energy. The properties of this layer are briefly discussed.Comment: 15 pages, 4 figures. Accepted to be publish in the ApJ Letters. Tar+gzip documen

Ressenyes

Obra ressenyada: Margaret BENT, Magister Jacobus de Ispania, Author of the «Speculum musicae». Farnham: Ashgate, 2015

La situación de la venta de contenidos on line en España: un estudio del lector de prensa digital

Actualmente es una realidad la dificultad del cobro por servicios on line. Sobre todo si estos servicios son de carácter generalista y se reproducen en muchos sitios web. Las actuales iniciativas de algunos periódicos para cobrar no tienen todavía el suficiente valor añadido para que los usuarios paguen. Muchas veces el tráfico que pierden, y por lo tanto los ingresos de publicidad on line que dejan de ingresar, representan una mayor cantidad económica que el dinero que les suponen las nuevas suscripciones. En el presente trabajo se pretende estudiar el comportamiento de los lectores de diarios on line, identificando cuales son los principales elementos que este tipo de lectores valoran para posteriormente realizar una buena estrategia de contenidos de pago