We present a numerical solution for complete population inversion in a four-level ladder system obtained by using a full π-pulse illumination scheme with resonant ultrashort phase-locked Gaussian laser pulses. We find that a set of pulse areas such as √ 3π, 2π, and √ 3π completely inverts the four-level system considering identical effective dipole coupling coefficients. The solution is consist...

Most natural populations of Drosophila pseudoobscura are mixtures of individuals homozygous and heterozygous for gene arrangements in the third chromosome. The relative frequencies of the gene arrangements in populations show geographical and temporal variations. On Mount San Jacinto and in the Sierra Kevada in California, and in some localities in Texas, the temporal variations are cyclic and ...

Puerperal uterine inversion is a severe but rare obstetric complication of yet unknown origin. In this two-year study we determine the incidence of this complication and we describe associated risk factors to expose its etiology. All cases of uterine inversion were included from a nationwide cohort study which contained all 98 hospitals with a maternity unit in the Netherlands. We reviewed the ...

Discrete choice models normally represent the utility values of a finite set of mutually exclusive and exhaustive choice alternatives in terms of an expected value and an error. Strong assumptions are introduced on the error term. A different approach is sketched here. We assume that each member of a population of decision makers has a utility function, and that these functions can be scaled to...

In this paper we investigate the usefulness of a new operator, inver-over, for an evolutionary algorithm for the TSP. Inver-over is based on simple inversion, however, knowledge taken from other individuals in the population in uences its action. Thus, on one hand, the proposed operator is unary, since the inversion is applied to a segment of a single individual, however, the selection of a seg...

Non-radiative (phonon scattering) lifetimes are calculated for asymmetric quantum well structures in the AlGaAs/GaAs materials system. Structures are designed in a 3-level optically pumped laser configuration, and tuned for emission in the terahertz frequency range. For emission frequencies below 8.7THz, the energy gap of the lasing levels is less than the LO phonon energy in GaAs, which leads ...

Periodical switching laser pulses with nanosecond pulse width and several kilowatts peak power from wideseparated multilongitudinal-mode oscillation were observed experimentally in laser-diode pumped passively Q-switched Yb:YAG microchip laser with Cr:YAG as saturable absorber. Pulses from different longitudinal modes oscillate alternatively. Periodical pulses oscillation dynamics induced by sp...

The intrinsic conformational and structural properties of the tropinone azabicycle have been investigated in a supersonic jet expansion using rotational spectroscopy. The spectrum revealed the presence of equatorial and axial conformers originated by the inversion of the N-methyl group, with the tropane motif adopting a distorted chair configuration. The determination of substitution and effect...

We have observed both superluminal and ultraslow light propagation in an alexandrite crystal at room temperature. Group velocities as slow as 91 meters per second to as fast as -800 meters per second were measured and attributed to the influence of coherent population oscillations involving chromium ions in either mirror or inversion sites within the crystal lattice. Namely, ions in mirror site...

Anopheles arabiensis, one of the two most potent malaria vectors of the gambiae complex, is characterized by the presence of chromosomal paracentric inversions. Elucidation of the nature and the dynamics of these inversions is of paramount importance for the understanding of the population genetics and evolutionary biology of this mosquito and of the impact on malaria epidemiology. We report he...