If a pulsar orbits a supermassive black hole, the timing of pulses that pass close to the hole will show a variety of strong field effects. To compute the intensity and timing of pulses that have passed close to a nonrotating black hole we introduce here a simple formalism based on two “universal functions,” one for the bending of photon trajectories and the other for the photon travel time on ...

The paper presents a comparative study of electropermeabilization of cells in suspension by unipolar and symmetrical bipolar rectangular electric pulses. While the parameters of electropermeabilization by unipolar pulses have been investigated extensively both in cell suspensions and in tissues, studies using bipolar pulses have been rare, partly due to the lack of commercially available bipola...

We study the stability and interactions of chirped solitary pulses in a system of nonlinearly coupled cubic Ginzburg-Landau (CGL) equations with a group-velocity mismatch between them, where each CGL equation is stabilized by linearly coupling it to an additional linear dissipative equation. In the context of nonlinear fiber optics, the model describes transmission and collisions of pulses at d...

The space-time focusing of a (continuous) succession of localized X-shaped pulses is obtained by suitably integrating over their speed, i.e., over their axicon angle, thus generalizing a previous (discrete) approach. New superluminal wave pulses are first constructed and then tailored so that they become temporally focused at a chosen spatial point, where the wave field can reach very high inte...

Ultrafast pulses on the femtosecond time scale allow fundamental processes, such as atomic transitions, to be measured. To investigate the formation of optical pulses, an argon ion laser was used to pump a titanium-doped sapphire laser. The mode-locked output of this laser was measured with a spectrometer and an autocorrelator to find a frequency pulse width of σω = 86 ± 3 rad/ps and a temporal...

Recently, a real-time imaging system based on terahertz (THz) time-domain spectroscopy has been demonstrated. This technique offers a range of unique imaging modalities due to the broad bandwidth, sub-picosecond duration, and phase-sensitive detection of the THz pulses. This paper provides a brief introduction of the state-of-the art in THz imaging. It also focuses on expanding the potential of...

We present high-resolution multi-frequency single-pulse observations of the Vela pulsar, PSR B0833−45, aimed at studying micro-structure, phase-resolved intensity fluctuations and energy distributions at 1.41 and 2.30 GHz. We find micro-structure in about 80% of all pulses independent of observing frequency. The width of a micropulse seems to depend on its peak flux density, whilst quasi-period...

Resource pulses affect productivity and dynamics in a diversity of ecosystems, including islands, forests, streams, and lakes. Terrestrial and aquatic systems differ in food web structure and biogeochemistry; thus they may also differ in their responses to resource pulses. However, there has been a limited attempt to compare responses across ecosystem types. Here, we identify similarities and d...

Apical constriction is a cell shape change that promotes epithelial bending. Activation of nonmuscle myosin II (Myo-II) by kinases such as Rho-associated kinase (Rok) is important to generate contractile force during apical constriction. Cycles of Myo-II assembly and disassembly, or pulses, are associated with apical constriction during Drosophila melanogaster gastrulation. It is not understood...

[1] We analyzed high-speed video images and corresponding current records for eight upward lightning flashes initiated by the Peissenberg tower (160 m) in Germany. These flashes contained a total of 33 measurable initial stage (IS) current pulses, which are superimposed on steady IS currents. Seven IS pulses had relatively short (<8 ms) 10-to-90% risetimes and 26 IS pulses had relatively long (...