10 papers
A Home Experiment in Elasticity
J. M. Aguirregabiria, A. Hernández, M. Rivas
We analyze a simple problem in elasticity: the \emph{initial} motion of an elastic bar that after being hanged from an end is suddenly released. In a second problem a point mass is…
Order Reductions of "Predictive Dynamical Systems"
J. M. Aguirregabiria
It has been recently pointed out that dynamical systems depending on future values of the unknowns may be useful in different areas of knowledge. We explore in this context the ext…
Quintessence as k-essence
Juan M. Aguirregabiria, Luis P. Chimento, Ruth Lazkoz
Quintessence and k-essence have been proposed as candidates for the dark energy component of the universe that would be responsible of the currently observed accelerated expansion.…
Linear Momentum Density in Quasistatic Electromagnetic Systems
J. M. Aguirregabiria, A. Hernandez, M. Rivas
We discuss a couple of simple quasistatic electromagnetic systems in which the density of electromagnetic linear momentum can be easily computed. The examples are also used to illu…
A note on the structural stability of tachyonic inflation
J. M. Aguirregabiria, Ruth Lazkoz
We study the structural stability of tachyonic inflation against changes in the shape of the potential. Following Lidsey (Gen. Rel. Grav. 25 (1993) 399), the concepts of rigidity a…
Phantom k-essence cosmologies
Juan M. Aguirregabiria, Luis P. Chimento, Ruth Lazkoz
We devise a method to obtain a phantom version of FRW k-essence cosmologies with homogeneous k-fields by applying form-invariance transformations. It can be seen that the transform…