Experiments demonstrate a dramatic decrease in polarization-instability threshold as an optical pulse is tuned near the short-wavelength edge of the photonic bandgap formed by a fiber Bragg grating. These enhanced nonlinear interactions and birefringent effects are modeled with coupled-mode numerical simulations. Nonlinearities are shown to increase much more rapidly than the effective birefrin...

The aim of the study was to assess the effect of absence of atrial contraction during exercise. During the incremental ergometer exercise tests, heart rate, oxygen uptake, and oxygen pulse in patients with isolated atrial fibrillation were compared with those in control subjects at rest, at the exercise level of gas exchange anaerobic threshold, and at peak exercise. The study population consis...

The model of a flip-flop consisting of an interacting pair of completely equivalent chemical reaction systems (branches) is displayed. Beyond a critical threshold value of the influx to the apex substance of both branches the symmetric state (both brandies active to an equal extent) is unstable; so essentially only one will be active. A negative pulse in the influx beneath the threshold brings ...

We show that surface swelling is the first step in the interaction of a single femtosecond laser pulse with PMMA. This is followed by perforation of the swollen structure and material ejection. The size of the swelling and the perforated hole increases with pulse energy. After certain energy the swelling disappears and the interaction is dominated by the ablated hole. This behaviour is independ...

A theoretical study of super generation in photonic crystal fiber and its application to pulse compression is presented. The evolution of the spectrum can be divided into three stages: initial broadening below a certain threshold propagation distance, dramatic broadening to a supercontinuum at a threshold distance, and, finally, saturation of the spectral width on propagation. It is found that ...

In this paper, a novel statistical approach is presented for time-of-arrival (TOA) estimation based on first path (FP) pulse detection using a sub-Nyquist sampling ultra-wide band (UWB) receiver. The TOA measurement accuracy, which cannot be improved by averaging of the received signal, can be enhanced by the statistical processing of a number of TOA measurements. The TOA statistics are modeled...

Application of picosecond and femtosecond laser pulses to the controlled ablation of materials represents a relatively unexplored yet important topic in laser processing. Such ultrashort pulses are of potential value in areas of thin-film deposition, micromachining, and surgical procedures. We report here some early results of systematic studies being done from the femtosecond to the nanosecond...

We consider pulse formation dynamics in an actively mode-locked laser. We show that an amplitudemodulated laser is subject to large transient growth and we demonstrate that at threshold the transient growth is precisely the Petermann excess noise factor for a laser governed by a nonnormal operator. We also demonstrate an exact reduction from the governing PDEs to a low-dimensional system of ODE...

The effects of pulse rate on absolute threshold ~THS!, maximum acceptable loudness ~MAL!, and dynamic range ~DR! were evaluated in 15 Clarion cochlear implant users. A wider range of pulse rates was assessed than in previous studies, and subjects with both standard and perimodiolar electrode arrays were tested. THS and MAL decreased with pulse rate, and DR increased with pulse rate, for pulse r...

We use an interferometric time-resolved observation of a femtosecond-laser pulse (800 nm/45 fs) interaction with glass from 100 fs to 10 ns at spatial lateral resolution down to the wavelength of the pulse. The phase and amplitude images reveal sequence of events after the irradiation of a single ultra-short laser pulse at close-to-threshold intensity when permanent refractive index changes occ...