Origin of second-harmonic generation in the incommensurate phase of K2SeO4

We show that a ferroelectric phase transition takes place in the incommensurate phase of the K2SeO4 crystal. The ferroelectric character of the IC phase explains the second-harmonic generation observed in the corresponding temperature range.Comment: 5 pages, 1 figur

Acoustic wave controlled X-ray diffraction and emission processes in crystals

Possibilities to exert control over electromagnetic processes in a crystal by an acoustic wave are considered. The influence of such a wave on the parametric X-ray radiation and coherent bremsstrahlung from relativistic electrons in a crystal are studied in this paper

Ablation and transmission of thin solid targets irradiated by intense extreme ultraviolet laser radiation

The interaction of an extreme ultraviolet (EUV) laser beam with a parylene foil was studied by experiments and simulation. A single EUV laser pulse of nanosecond duration focused to an intensity of 3 × 1010 W cm−2 perforated micrometer thick targets. The same laser pulse was simultaneously used to diagnose the interaction by a transmission measurement. A combination of 2-dimensional radiation-hydrodynamic and diffraction calculations was used to model the ablation, leading to good agreement with experiment. This theoretical approach allows predictive modelling of the interaction with matter of intense EUV beams over a broad range of parameters

Thunderstorm ground enhancements: Multivariate analysis of 12 years of observations

We present a survey of more than a half-thousand thunderstorm ground enhancements (TGEs, fluxes of electrons, and gamma rays associated with thunderstorms) registered in 2008–2022 at Aragats space environmental center (ASEC). We analyze correlations between various measured parameters characterizing TGEs measured on Aragats. Two special cases of TGE events are considered: one, terminated by nearby lightning flashes, and another one—with a sufficiently large ratio of electrons to gamma rays. On the basis of the analysis, we summarize the most important results obtained during 12 years of TGE study, which include the following statements: (i) TGEs originated from multiple relativistic runaway electron avalanches starting with seed electrons from the ambient population of cosmic rays, which enter an extended region of the electric field with strength exceeding the critical value; (ii) quite frequently, TGEs occur prior to lightning flashes and are terminated by them; (iii) the energy spectra of avalanche electrons observed on Aragats indicate that the strong electric field region can extend very low above the ground covering a large area on the earth’s surface

The Creation of Radiation Dominated Plasmas Using Laboratory X-Ray Lasers

When short wavelength extreme ultraviolet (EUV) and X-ray laser radiation is focused onto solid targets, narrow deep features are ablated and a dense, low-temperature plasma is formed. We examine the radiation dominated plasma formed by 46.9 nm laser radiation focused onto solids and show that ionisation can be significantly modified by electron degeneracy effects. Some experimental and theoretical considerations for investigating the interaction of capillary discharge lasers operating at 46.9 nm with solid and gas targets are presented

The Observed Correlations for the Strange Multibaryon States in Systems with Λ\Lambda-Hyperon from pa Collision at Momentum of 10 Gev/cc

he observed well-known resonances $\Sigma^0$ $\Sigma^{*+}$(1385) and $K^{*\pm}$(892) from PDG are good tests of this method. Exotic strange multibaryon states have been observed in the effective mass spectra of: $\Lambda \pi^{\pm}$,$\Lambda \gamma$, $\Lambda p$, $\Lambda p p$ subsystems. The mean value of mass for $\Sigma^{*-}(1385)$ resonance is shifted till mass of 1370 MeV/$c^2$ and width is two times larger than the same value from PDG. Such kind of behavior for width and invariant mass of $\Sigma^{*-}(1385)$ resonance is interpreted as extensive contribution from stopped $\Xi^-\to\Lambda\pi^-$ and medium effect with invariant mass. The mean value of mass for $\Sigma^{*+}(1385)$ from secondary interactions is also shifted till mass of 1370 MeV/$c^2$. The width of $\Sigma^0$ is $\approx$ 2 times larger than the experimental error. There are enhancement production for all observed hyperons.Comment: 4 pages, 6 figures, XXIst Rencontres de Blois "Windows on the Universe " Blois, France June 21st - June 26th, 200

Surgical treatment of wounded persons with complicated thoracic damages

Objective. To improve the results of complex surgical treatment of wounded and injured persons with thoracic trauma, complicated by bronchopleural fistulas, pleural empyema and defects in the thoracic wall soft tissues, basing on introduction of the proposed procedure of vacuum therapy in combination with bronchoscopic obturation of certain bronchus. Materials and methods. Analysis of results of the complex surgical help delivery for 54 wounded persons with defects of the thoracic wall soft tissues, broncho-pleural fistulas and pleural empyema, caused by the combat thoracic trauma, on ІІІ and ІV levels of medical support while conduction of the Antiterrorist operation/Operation of the Joined Forces (the main group) and 73 injured persons with thoracic trauma of the peace period (the comparison group) in the 2014 - 2019 yrs period was conducted. Results. Improvement of complex surgical treatment of the wounded and damaged persons with thoracic trauma and defects of the thoracic wall soft tissues have permitted to reduce the complications frequency by 6.7%, and lethality - by 9.2% in the main group. Conclusion. There was proposed a procedure of vacuum therapy, ultrasound cavitation together with bronchoscopic bronchial obturation for its fistula, which have proved its efficacy in complex surgical treatment of severely wounded persons with the gun-shot thoracic damages and presence of combination of pleural empyema, bronchial fistula and defects of soft tissues