Current-voltage measurements in electrical impedance tomography (EIT) can be partially ordered with respect to definiteness of the associated self-adjoint Neumann-to-Dirichlet operators. With this ordering, a pointwise larger conductivity leads to smaller current-voltage measurements, and smaller conductivities lead to larger measurements. We present a converse of this simple monotonicity relat...

A hypothesis about what is the principal cognitive precondition of successful systematic acquainting children with computers is put forward. For this, the notion of the Thought-Producing Self of the child is introduced. It is stated that the System of Emotional-Imaginative Teaching (EIT-system) based on the Theory of Dynamic Conceptual Mappings allows for realizing the Thought-Producing Self of...

We suggest a technique for producing subfemtosecond pulses of radiation. The technique is based on using electromagnetically induced transparency to produce a strongly driven molecular coherence. This coherence results in a Raman spectrum with Bessel function amplitudes and phases corresponding to a frequency modulated signal, thereby allowing compression by the group velocity dispersion of the...

In this paper we show that rotational invariance can be improved in a neural network based EIT reconstruction approach by a suitably chosen permutation of the input data. The input space is partitioned to non-overlapping sectors, and the input signal is permuted so that it lies in one sector independent of the original rotation angle. We demonstrate the advantages of the method with computer si...

Calculating test validity as an instrument of educational achievement level determination, is one of the main research tasks, especially on a state level. The system of HEI admission must be based on the principles of fairness and openness. This can only be achieved by conducting systematic admission test result analysis both in the context of organization processes and within the assessment of...

We analyze both experimentally and theoretically the phase shift of a fixed coupling laser field in a L-type system induced by a tunable probe laser field. The measurements are performed with a heterodyne interferometer on a beam of cesium atoms in the D2 line. This system exhibits electromagnetically induced transparency with a rapidly varying refractive index. The parametric dispersion of the...

We have experimentally studied the optical bistable behavior in an optical ring cavity filled with a collection of three-level L-type rubidium atoms, interacting with two collinearly propagating laser beams. The bistability so observed is very sensitive to the induced atomic coherence in this electromagnetically induced transparency system or consequently to the altered nonlinearity in the syst...

Kevin Cox,1 Valery I. Yudin,2,3,4 Alexey V. Taichenachev,2,3,4 Irina Novikova,1 and Eugeniy E. Mikhailov1 1Department of Physics, College of William & Mary, Williamsburg, Virginia 23185, USA 2Institute of Laser Physics SB RAS, Novosibirsk RU-630090, Russia 3Novosibirsk State Technical University, Novosibirsk RU-630092, Russia 4Novosibirsk State University, Novosibirsk RU-630090, Russia (Receive...

The electromagnetically induced transparency (EIT) in an N configuration is studied under both resonant and off-resonant conditions. In a certain off-resonant condition the dark state of the four level system, which is almost the same as the resonant dark state in Λ configuration, is rebuilt. The actual system with damping is examined using optical Bloch equation, both numerically and analytica...