We determine the semiclassical coherent-state propagator for a particle going through one-dimensional evolution in a simple barrier potential. The described semiclassical method makes use of complex trajectories which, by its turn, enables the definition of (real) traversal times in the complexified phase space. We then discuss the behavior of this time for a wave packet whose average energy is below the barrier height.

In this paper we present thoughtful comments on the paper `Bessel beams and signal propagation' showing that the main claims of that paper are wrong. Moreover, we take the opportunity to show the non trivial and indeed surprising result that a scalar pulse (i.e., a wave train of compact support in the time domain) that is solution of the homogeneous wave equation (vector ($\vec{E},\vec{B}$) pulse that is solution of Maxwell equations) is such that its {\em wave front} in some cases does travel with speed {\em greater} than $c$, the speed of light . In order for a pulse to posses a front that travels with speed $c$, an additional condition must be satisfied, namely the pulse must have finite energy. When this condition is fulfilled the pulse still can show peaks propagating with superluminal (or subluminal) velocities, but now its wave front travels at speed $c$. These results are important because they explain several experimental results obtained in recent experiments, where superluminal velocities have been observed, without implying in any breakdown of the Principle of Relativity.Comment: 14 pages, 2 figures, misprints corrected, accepted for publication in Phys. Lett. A With some misprints correcte

This paper exposes initially the motivations for developing a TRL online calculator by AEB (Brazilian Space Agency; in Portuguese, Agência Espacial Brasileira). Such motivations demand the tool to be a way not only to assess the TRL condition of operational space missions and systems, but also as a method of evaluating and sharing proposals with new technological content. The TRL methodology and its relation to risk management are discussed. The development phases of the IMATEC Lite application are then described, with emphasis to the data handling structure capable of storing the user product model. A result of technology assessment using the software is detailed by presenting the PBS of the SERPENS 1 mission nanosatellite. The prospects of using the tool for judging the acceptability of new missions and projects are discussed, as well as some of the encountered difficulties.