We show that the group delay in tunnelling is not a traversal time but a lifetime of stored energy or stored probability escaping through both ends of the barrier. Because it is a lifetime associated with both forward (transmitted) and backward (reflected) fluxes, it cannot be used to define a group velocity for forward transit in cases where a wavepacket is mostly reflected. For photonic tunne...

The echolocating bat, Eptesicus fuscus, perceives the distance to sonar targets from the delay of echoes and the shape of targets from the spectrum of echoes. However, shape is perceived in terms of the target's range proftle. The time separation of echo components from parts of the target located at different distances is reconstructed from the echo spectrum and added to the estimate of absolu...

We present a simple electronic circuit that produces negative delays. When a pulse is sent to the circuit as input, the output is a pulse with a similar wave form that is shifted forward in time. The advance time or negative delay can be increased to the order of seconds so that we can observe the advance with the naked eye by observing two light emitting diodes that are connected to the input ...

A method for performing waveform invariant time stretching and pitch shifting on a quasi harmonic and sinusoidally modeled sound is presented. The method is based on the relative phase delay representation of the phase, defined as the difference between the phase delay of the partials and the phase delay of the fundamental. This representation makes the waveform characterization independent fro...

The magnetostrictive guided wave sensor with a single induced winding cannot distinguish axially symmetric from non-axially symmetric features in a pipe, because it is impossible for the sensor to detect the non-axially symmetric mode waves. When we study the effect of the change of the magnetic field in the air zone for receiving the longitudinal guided wave mode, we find that the change of th...

We study ultrabroadband slow light in a warm rubidium vapor cell. By working between the D1 and D2 transitions, we find a several-nanometer window centered at 788:4 nm in which the group index is highly uniform and the absorption is small (<1%). We demonstrate that we can control the group delay by varying the temperature of the cell, and we observe a tunable fractional delay of 18 for pulses a...

Electromagnetic (EM) Metamaterials have specific EM properties that cannot be found in nature (Caloz & Itoh, 2006). These specific EM properties are obtained by the artificial structures, rather than the composition of the metamaterials, and affect the propagations of EM waves when the average structure sizes are much smaller than the guided wavelengths ┣g, i.e., at least smaller than ┣g/4. Sin...

We determined the separations of the radio sources in the triangle formed by the BL Lac objects 1803+784 and 2007+777, and the QSO 1928+738 from in-tercontinental interferometric observations carried out in November 1991 at the frequencies of 2.3 and 8.4 GHz. Difference phase-delay astrometry yielded the following separations: ∆α (1803+784)−(1928+738) =–1 h 27 m 2.

Traffic jam often occurs around the signalized intersection because each takes “stop-and-go cost” to pass through the intersection. Hence, traffic signal control has significant meanings in reducing the traffic jams efficiently. A modification method of traffic signal control management based on self-organizing is introduced. The self-organizing observed in non-linier coupled oscillators is ref...