The Poynting vector, energy density and energy velocity of light pulses propagating in anomalous dispersion medium (used in WKD-like experiments) are calculated. Results show that a negative energy density in the medium propagates along opposite of incident direction with such a velocity similar to the negative group velocity while the direction of the Poynting vector is positive. In other word...

background: an imbalance of the cerebrovascular response during functional activation of the brain has been postulated as a factor in the pathophysiology of migraine. the purpose of this study was to determine the transcranial doppler sonography (tds) diagnostic value for the cerebral flow velocity changes in the interictal phase of classic migraine. methods: this study was carried out on 46 pa...

The phase velocity of plane waves propagating in an isotropic chiral medium can be simultaneously positive for left–circularly polarized light and negative for right–circularly polarized light (or vice versa). The constitutive parameter regimes supporting this phenomenon are established for nondissipative and dissipative mediums. The boundary between positive and negative phase velocity is char...

Any charged particle moving faster than light through a medium emits Cherenkov radiation. We show that charged particles moving faster than light through the vacuum emit Cherenkov radiation. How can a particle move faster than light? The weak speed of a charged particle can exceed the speed of light. By definition, the weak velocity ^v&w is ^C f inuvuC in&/^C f inuC in&, where v is the velocity...

Any charged particle moving faster than light through a medium emits Cherenkov radiation. We show that charged particles moving faster than light through the vacuum emit Cherenkov radiation. How can a particle move faster than light? The weak speed of a charged particle can exceed the speed of light. By definition, the weak velocity v w is Ψ f in |v|Ψ in /Ψ f in |Ψ in , where v is the velocity ...

Imaging Laser Doppler Velocimetry (ILDV) is a flow measurement technique which facilitates the measurement of one velocity component of a flow field in an imaging plane. It is an evolution of Heterodyne Doppler Global Velocimetry and may be regarded as the planar extension of the classical dual beam LDV by crossing two light sheets in the flow instead of focused laser beams. With different ligh...

Ability to control the velocity of light is usually referred to as slow or fast light depending on whether the group velocity of light is reduced or increased. The slowing of light as it passes through the glass to 2/3 rd its original value is a well known phenomenon. This slowing down happens due to the interaction of light with the electrons in the medium. As a general principle, stronger the...

We report the simulation results for impact of nonlinear Kerr effect on band structures of a ‎two dimensional photonic crystal (2D-PhC) with no defect, a PhC based W1-waveguide ‎‎(W1W), and also Coupled-Cavity Waveguides (CCWs). All PhC structres are assumed to a ‎square lattice of constant a made of GaAs rods of radius r=0.2a, in an air background. The ‎numerical simulation was performed using...

Conventional velocity analysis applied to images produced by wave-equation migration with a cross-correlation imaging condition makes use either of moveout information from space-lags or of focusing information from time-lags. However, more robust velocity estimation methods can be designed to take advantage simultaneously of the moveout and focusing information provided by the migrated images....