Resonant nonstationary amplification of polychromatic laser pulses and conical emission in an optically dense ensemble of neon metastable atoms

Experimental and numerical investigation of single-beam and pump-probe interaction with a resonantly absorbing dense extended medium under strong and weak field-matter coupling is presented. Significant probe beam amplification and conical emission were observed. Under relatively weak pumping and high medium density, when the condition of strong coupling between field and resonant matter is fulfilled, the probe amplification spectrum has a form of spectral doublet. Stronger pumping leads to the appearance of a single peak of the probe beam amplification at the transition frequency. The greater probe intensity results in an asymmetrical transmission spectrum with amplification at the blue wing of the absorption line and attenuation at the red one. Under high medium density, a broad band of amplification appears. Theoretical model is based on the solution of the Maxwell-Bloch equations for a two-level system. Different types of probe transmission spectra obtained are attributed to complex dynamics of a coherent medium response to broadband polychromatic radiation of a multimode dye laser.Comment: 9 pages, 13 figures, corrected, Fig.8 was changed, to be published in Phys. Rev.

Rigottotomy and lipofilling in the treatment of post-burn deformations in children: our experience

Actuality: rigottotomy and lipofillingis a method of surgical correction of post-burn deformities and scars. Rigottotomy increases the area of the reconstructed segment, which in the future, when performing lipofilling, allows to restore the contours and volume. The purpose of the study: evaluation of the advantages of this method compared to classical surgical operations. Patients and methods: we evaluated the results of treatment of 25 children with post-traumatic deformities and post burn scars and deformities of various localization. The stages of surgical correction: the first stage - the actual liposuction (tumescent). The second stage (primary) - preparing a donor bed to transplant fat cells. Implementation of rigottotomy (formation of channels crossing the scarred tissue in different planes) which are filled with lipoaspirates.The third stage – subcutaneous and/ or intradermal injection oflipografts to fill the volume with contour deformities. Patients divided into groups: the first group is about 10 children with a contoured deformation (post-burn and post-traumatic). The treatment was performed in several stages (at least 3). The first step is to fill no more than 20-30% of the area of the defect. For surgical correction of patients of this group were mainly used fat grafting. The second group of 9 children with hypertrophic scars and contractures of large joints. First stage is aggressive rigottotomy and subsequent intradermal injection of litografts to correct contractures. The third group is a group of 6 children with post-burn scars, violations of the structural composition of the skin. All patients have necessitated the 1-2 stages of lipofilling in combination with rigottotomy that helped to improve the quality of the skin and partly to eliminate cosmetic defect. All patients have received a good cosmetic and functional result. There were not any complications. Conclusion: advantages of this technique are: reducing the time of hospitalization; elimination of cosmetic defects and deformities; formation and recovery of the subcutaneous fat layer; improve the elasticity of the skin

Electrostatic interactions and stability of dusty plasmas and the multicomponent Ornstein-Zernike equation

[EN] Using the Ornstein-Zernike integral fluid equation for multi-component plasma, the dielectric properties and thermodynamical stability of dusty plasmas are studied. For the most non-ideal dust plasma subsystem, a transition to the one-component approximation is carried out. It is shown that the effective pseudopotential for determining the correlation functions in the selected subsystem should not include the contribution of this subsystem to the screening constant but also take into account the condition of total plasma quasineutrality. It is demonstrated that when the coupling parameter of the dust subsystem is smaller than unity, Gamma(00) 1, the static dielectric function in the long wavelength domain becomes negative, and this domain expands when Gamma(00) increases. This leads to the appearance of attraction of particles with charges of the same sign and repulsion of particles with charges of the opposite sign. In this case, both the total pressure and the isothermal compressibility in the entire studied range of the coupling parameter Gamma(00) 2 is thermodynamically unstable.This study was developed within Project No. 16-12-10424 supported by the grant from the Russian Science Foundation, and the numerical simulations were carried out as a part of the State assignment financed by the Ministry of Science and Higher Education of the Russian Federation (Project No. 0038-2019-0005).Tkachenko Gorski, IM.; Filippov, A.; Fortov, VE.; Reshetniak, V.; Starostin, A. (2020). Electrostatic interactions and stability of dusty plasmas and the multicomponent Ornstein-Zernike equation. AIP Advances. 10(4):1-14. https://doi.org/10.1063/1.514490111410