Lightning return stroke is a self-propagating discharge with path length measured in kilometres, which extends at high speeds, sometimes approaching a significant fraction of the speed of light. Usually one is interested in the electromagnetic fields produced by lightning several tens of meters to some kilometres away. In order to calculate fields from lightning, it is modelled as a linear trav...

Electric currents induced in conductive planetary interiors by time-varying magnetospheric and ionospheric current systems have a significant effect on electromagnetic (EM) field observations. Complete characterization of EM induction effects is difficult owing to nonlinear interactions between the three-dimensional electrical structure planet spatial complexity inducing systems. We present, ge...

We present a small-signal wave propagation theory on matter-wave superradiant scattering. We show, in a longitudinally excited condensate, that the backward-propagating, superradiantly generated optical field propagates with ultraslow group velocity and that the small-signal gain profile has a Bragg resonance. We further show a unidirectional suppression of optical superradiant scattering, and ...

abstract: the dust is one of the weather phenomena that have negative environmental effects and consequences. the central city of ahvaz in khuzestan province is one of cities that in every year witnessed the dust in its environment. in this study, after determining that the dust phenomena data are abnormal, using the sen's nonparametric model been proceed to modeling of changes and survey ...

We derive a correspondence between the contour integration of the Casimir stress tensor in the complex-frequency plane and the electromagnetic response of a physical dissipative medium in a finite real-frequency bandwidth. The consequences of this correspondence are at least threefold: First, the correspondence makes it easier to understand Casimir systems from the perspective of conventional c...

We use QCD sum rules for the three point function of a pseudoscalar and two nucleonic currents in order to estimate the charge dependence of the pion nucleon coupling constant gNNπ coming from isospin violation in the strong interaction. The effect can be attributed primarily to the difference of the quark condensates < ūu > and < d̄d >. Assuming that the π is a pure isostate we obtain for the s...

The development of time-resolved scanning tunnelling microscopy (STM), in particular, attempts to combine STM with ultrafast laser technology, is reviewed with emphasis on observed physical quantities and spatiotemporal resolution. Ultrashort optical pulse technology has allowed us to observe transient phenomena in the femtosecond range, which, however, has the drawback of a relatively low spat...

We propose a sequence of experiments with the goal of exploring electromagnetic induction phenomena and “magnetic friction” forces. The experiments have been tested with high school students in the context of a program of cooperation between our Physics Department and the Regional School District. The experiments involve permanent magnets and conductors (a coil of wire or an aluminium plate) in...