Nonlinear increase in the energy input into a medium at the fusion of regularized femtosecond filaments

We consider dark matter consisting of long-living particles with masses 10⁷ GeV ? M ?10¹⁶ GeV decaying through hadronic channel as a source of high-energy neutrino. Using recent data on high-energy neutrino from IceCube and Pierre Auger experiments, we derive the upper-limits on neutrino flux from dark matter decay and constraints on dark matter parameter space. For the dark matter masses of order 10⁸ GeV the constraints derived are slightly stronger than those obtained for the same dark matter model using the highenergy gamma-ray limits.     

Observation of filamentation-induced continuous self-frequency down shift in air

We observed a new filamentation nonlinear process: continuous self-frequency down shift inside the filament zone during the propagation of a femtosecond laser pulse in air. The frequency shift depends strongly on the length of the self-guided column (filament). PACS 42.65.Dr; 42.65.Jx; 52.35.Mw     

Bis-arylsulfonamide Derivatives of 2-Amino-5(6)-(4-aminophenylthio)benzimidazole

Three different procedures have been developed for the preparation of bis-arylsulfonamide derivatives of 2-amino-5(6)-(4-aminophenylthio)benzimidazole, and biological activity of the products have been studied.     

Effect of beam diameter on the propagation of intense femtosecond laser pulses

This paper describes the effects observed during the propagation of intense femtosecond laser pulses in air following the modification of the laser beam diameter with a pair of convex–concave lenses placed/mounted in a telescopic configuration. We observed that by reducing the diameter of the beam the detected back-scattered nitrogen fluorescence from the filaments becomes more stable on a shot-to-shot basis while, for a larger beam size, greater fluctuations are observed that are not correlated to shot-to-shot fluctuations in the laser pulse energy. This result leads to a new method to control the fluorescence signal which can be very important in remote-sensing applications. PACS 42.65.Jx; 42.68.Ay; 42.68.Wt     

Structural reasons for the perpendicular anisotropy in ferrospinel single-crystal films

Results of investigations into the perpendicular anisotropy of ferrospinel single crystal films are analyzed. The exchange interaction constants and the contribution of the exchange energy, energy of crystallographic anisotropy, and perpendicular anisotropy to the domain wall energy density are estimated. It is demonstrated that the parameters characterizing the perpendicular anisotropy depend on the chemical composition, degree of structure imperfection, and technological conditions of synthesis. The conclusion is drawn that the perpendicular anisotropy is caused by the magnetic constants of the material, macro- and microstresses, and anisotropy of the crystal shapes.     

Modern state of underground storage of liquid radioactive waste

Underground storage of liquid radioactive waste (LRW) has been successfully carried out in Russia over the past 40 years. Stages of development of the technology, its realization and chemical transformations of LRW components are considered and discussed, as well as the modern approach to underground storage. Control of the state of waste products and migration radionuclides and toxic compounds remains the key issue of providing safety of LRW storage. Radiation thermal and biochemical transformations of components of waste form new chemical compounds and, first of all, gases. The formation of gases is one of the important factors determining the safety of underground LRW storage.     

Investigation of the transformation of the spectrum of femtosecond laser radiation on filamentation in gas medium

The dependence of the parameters of femtosecond laser radiation (55 fs, 3.7 mJ, 800 nm) in a filament on the distance along the filament propagation axis, the diaphragm diameter, and the type and pressure of gas used for filamentation has been studied experimentally.     

3D Raman bullet formed under filamentation of femtosecond laser pulses in air and nitrogen

Complex experimental study of spectral, spatial and temporal behaviors of the IR shifted component observed under filamentation of the collimated femtosecond laser beam (80 GW, 50 fs, 805 nm) in molecular gases showed that this component behaves like a Raman soliton. Namely, it is confined in all domains: (a) it propagates within the filament core, (b) it has a stable duration of 30 fs along the filament, and (c) its spectrum shifts as a whole from 820 to 870 nm on the distance of 2 m from the filament start. A simple model explaining the origin of anomalous group velocity dispersion in the plasma channel of a filament is suggested.