Abstract
The main objective of this work is to investigate the correlation between meditation stages and the hypnagogic stages of sleep and awakening. It reports the study on the brain electric activity during Yôga Svásthya meditation stages. These data were obtained by means of scalp electroencephalograms (EEGs), and confronted with the stages of meditation and hypnagogic EEG stages. The latter were based on established criteria through the study of the duration of individual occurrences of each of the nine considered hypnagogic EEG stages. Analysis made concerns time, frequency, power and signal amplitude. The results show that meditation stages reach only the first two hypnagogic EEG stages, and the spectral analysis of the EEG confirmed a dominance of rapid rhythms (beta) while the presence of lower ones (delta and theta) are not significant.

Abstract
We describe a new regime of operation where sub-10-fs ultrashort laser pulses with symmetric spectra centered at 800 nm can be directly generated from a prism-dispersion-controlled modelocked Ti:sapphire oscillator that only uses commercially available standard optics.

Abstract
We report on simulation studies of thin plasma foils explosions upon interacting with high-intensity, ultra-short laser pulses. By using a fully relativistic Particle-in-cell code we describe the time-resolved position, momentum and energy of electrons and ions, for laser pulses with durations of tens of fs and intensities ranging from 10(20) W/cm(2) to 10(23) W/cm(2). Results show the generation of a Mev electron beam as well as supra-Mev ions. Ponderomotive Boost and Colombic Explosions are mechanisms used to explain the results.

Abstract
The effect of photon beam splitting in a time-varying medium is described by classical and quantum theoretical models. It generalizes the concept of time refraction, introduced recently by the authors as a natural extrapolation of the usual concepts of refraction and reflection into the time domain. Total time reflection is shown to exist. A sequence of time refraction processes is shown to lead to temporal interference effects. The concept of temporal beam splitter is introduced. Bogoliubov transformations for the temporal beam splitter are derived. Resonant amplification of light by change in time in the optical medium is shown to exist.

Abstract
In this work a wavelength multiplexing concept was demonstrated for frequency based self-referenced fibre optic intensity sensors relying on the utilisation of Bragg gratings and WDM couplers. The experimental results obtained showed a fairly good agreement with those predicted from the theory. It turned out that the system had negligible crosstalk between the two sensors. The resolution obtained for the sensors was found to be ˜0.05 dBvHz. It should be emphasised, that the sensing concept described in this work is particularly favourable in terms of the minimisation of system noise. This happens because what is monitored is the amplitude of two sinewaves, i.e., the detection bandwidth can be made as narrow as practically feasible, with the consequent decrease of the system noise level. The power budget of the sensing network can be improved if shorter lengths of delay fibre are used, with the penalty, however, of working with higher frequencies. On the other hand, if the reflectivity of the FBGs is optimised, the power received by the detectors will increase correspondingly. Finally, a proper choice of the coupling coefficient of the couplers in the reflective ladder topology will have a strong impact on the optical power levels reaching the detector unit. © 2002 IEEE.

Abstract
Theoretical and experimental results were presented which validated a new dual interferometric configuration with serrodyne processing for the remote sensing of electrical current. Linearity and waveform reproduction at 50 Hz were observed and a current resolution (˜22.4 ArmsHz- 1/2) was obtained. The utilization of the proposed interferometric concept to simultaneously perform metering and relaying current measurements was also addressed. © 2002 IEEE.