Generation, amplification, frequency conversion, and reversal of propagation of THz photons in nonlinear hyperbolic metamaterial.

We propose metamaterial (MM) that supports a mixture of three or more normal and backward electromagnetic modes with equal co-directed phase velocities and mutually contra-directed energy fluxes. This enables extraordinary three-wave mixing, greatly enhanced optical parametric amplification, and frequency-changing generation of entangled photons in the reflection direction. Proof-of-principle numerical simulation of such processes is presented based on the particular example of the wave-guided terahertz waves contra-propagating in the MM made of carbon nanotubes.

[Spectral Analysis of Sway of Human Body When Standing on Firm and Compliant Surfaces under Different Visual Conditions.].

The influence of different visual conditions on maintenance of vertical posture when standing on a firm and a compliant surface were compared. Motionless visual environment (MVE), closed eyes (CE) and virtual visual environment (VVE) were used as visual conditions. Displayed VVE included foreground and background.

Three-wave mixing of ordinary and backward electromagnetic waves: extraordinary transients in the nonlinear reflectivity and parametric amplification.

Three-wave mixing of ordinary and backward electromagnetic waves in a pulsed regime is investigated in the metamaterials that enable the coexistence and phase-matching of such waves. It is shown that the opposite direction of phase velocity and energy flux in backward waves gives rise to extraordinary transient processes due to greatly enhanced optical parametric amplification and frequency up- and down-shifting nonlinear reflectivity. The differences are illustrated through comparison with the counterparts in ordinary, co-propagating settings.

Negative group velocity and three-wave mixing in dielectric crystals.

We investigate extraordinary features of optical parametric amplification of Stokes electromagnetic waves that originate from the three-wave mixing of a backward phonon wave with negative group velocity and two ordinary electromagnetic waves. Such properties were earlier shown to exist only in plasmonic negative-index metamaterials that are very challenging to fabricate. Nonlinear optical photonic devices with properties similar to those predicted for negative-index metamaterials are proposed.

Microscopic mirrorless negative-index optical parametric oscillator.

The feasibility and extraordinary properties of mirrorless optical parametric oscillations in a microscopic strongly absorbing slab of negative-index metamaterial are shown. They stem from the backwardness of electromagnetic waves inherent with this type of metamaterial.

Coherence-controlled transparency and far-from-degenerate parametric gain in a strongly absorbing Doppler-broadened medium.

An inversionless gain of anti-Stokes radiation above the oscillation threshold in an optically dense far-from-degenerate double- ? Doppler-broadened medium accompanied by Stokes gain is predicted. The outcomes are illustrated with numerical simulations applied to sodium dimer vapor. Optical switching from absorption to gain via transparency controlled by a small variation of the medium and of the driving radiation parameters, which are at a level of less than one photon per molecule, is shown.

Four-wave mixing, quantum control, and compensating losses in doped negative-index photonic metamaterials.

The possibility of compensating absorption in negative-index metamaterials (NIMs) doped by resonant nonlinear-optical centers is shown. The role of quantum interference and the extraordinary properties of four-wave parametric amplification of counterpropagating electromagnetic waves in NIMs are discussed.

Compensating losses in negative-index metamaterials by optical parametric amplification.

Optical parametric amplification controlled by the auxiliary electromagnetic field enables transparency, amplification, and oscillation with no cavity in strongly absorbing negative-index metamaterials. The opposite directions of the wave vector and the Poynting vector in such materials result in extraordinary optical properties, including "backward" phase matching and the generation of entangled pairs of left- and right-handed counterpropagating photons.

Inversionless amplification by anisotropic molecules.

Switching from opaque via transparent to a strongly amplifying state is shown to be possible for molecular media without a change in the noninverted population of their energy levels.

[A surgical method for treating mandibular fractures].

The authors analyze the results of treatment of 60 patients with mandibular fractures, in whose treatment an improved V. V. Donskoĭ's method was used.

[Pathogenesis of Marcus Gunn palpebro-mandibular synkinesis].

Three patients with Marcus Gunn's synkinesis were examined. The clinical variants and time-course of synkinesis are offered. Factors provoking synkinesis manifestations are considered.

[Use of chromatography on a poly U-cellulose column for isolating eukaryote messenger RNAs].

The methods are described for increasing the flow rate of the column. The data are aduced, permitting to determine the capacity of the column, and optimal conditions for specific sorbtion with individual rabbit globin mRNA as an example.