Biomedical subjects

D Mugnai

Publications and source records attributed to D Mugnai.

14 recordsLinked to original sources

PubMed2006

Superluminal X-wave propagation: energy localization and velocity.

The electromagnetic propagation of a Bessel-X wave is analyzed on the basis of a vectorial treatment in order to obtain information about the propagation of energy flux and the velocity of the energy. Knowledge of these quantities is of great interest since they are connected to the production of localized electromagnetic energy and to the topic of superluminality, respectively. The electric and magnetic fields are obtained in the far-field approximation by considering a realistic situation able to generate a Bessel-X wave. The vectorial treatment confirms the capability of this kind of wave to localize energy, while, quite surprisingly, even if the group velocity is superluminal, the energy velocity is equal to the light speed.

Journal Article↗

PubMed2004

Real-time analysis of the telegrapher's equation for tunneling processes.

Based on a close analogy with an RLC circuit, a model for interpreting delay times in forbidden regimes (tunneling) is formulated, avoiding the analytical continuation into imaginary time. In this way, a reasonable description of experimental data, which were previously reported for a waveguide propagation below the cutoff frequency at approximately 9.5 GHz, is obtained.

Journal Article↗

PubMed2004

Unexpected behavior of crossing microwave beams.

An anomalous effect in the near field of crossed microwave beams, consisting in an unexpected transfer of modulation from one beam to the other, cannot be fully interpreted, at least not in a simple way, in terms of the usual electromagnetic or related framework. It is hypothesized that a local breaking of the Lorentz invariance, already invoked for an alternative interpretation of superluminal behaviors in these kinds of systems, could provide a partial explanation of the present results, although other interpretations cannot be completely ruled out.

Journal Article↗

PubMed2003

Tunneling as a stochastic process: a path-integral model for microwave experiments.

Delay time results obtained in microwave experiments at frequencies above and below the cutoff frequency of different waveguide sections are interpreted on the basis of wave propagation in the presence of dissipative effects. Kac's original suggestion was the starting point for the formulation of a stochastic model, which has now been substantially improved, also in relation to the transition-elements theory of Feynman-Hibbs. In this way, an approach to the problem is provided, which is completely distinct from the ones formulated elsewhere.

Journal Article↗

PubMed2000

Observation of superluminal behaviors in wave propagation

The possibility of observing superluminal behavior in the propagation of localized microwaves over distances of tens of wavelengths is experimentally demonstrated. These types of waves, better than the evanescent modes of tunneling, can contribute to answering the question on the luminal limit of the signal velocity.

Journal Article↗

PubMed1996