Interaction of quasilocal harmonic modes and boson peak in glasses

The direct proportionality relation between the boson peak maximum in glasses, $\omega_b$, and the Ioffe-Regel crossover frequency for phonons, $\omega_d$, is established. For several investigated materials $\omega_b = (1.5\pm 0.1)\omega_d$. At the frequency $\omega_d$ the mean free path of the phonons $l$ becomes equal to their wavelength because of strong resonant scattering on quasilocal harmonic oscillators. Above this frequency phonons cease to exist. We prove that the established correlation between $\omega_b$ and $\omega_d$ holds in the general case and is a direct consequence of bilinear coupling of quasilocal oscillators with the strain field.Comment: RevTex, 4 pages, 1 figur

Voronoi-Delaunay analysis of normal modes in a simple model glass

We combine a conventional harmonic analysis of vibrations in a one-atomic model glass of soft spheres with a Voronoi-Delaunay geometrical analysis of the structure. ``Structure potentials'' (tetragonality, sphericity or perfectness) are introduced to describe the shape of the local atomic configurations (Delaunay simplices) as function of the atomic coordinates. Apart from the highest and lowest frequencies the amplitude weighted ``structure potential'' varies only little with frequency. The movement of atoms in soft modes causes transitions between different ``perfect'' realizations of local structure. As for the potential energy a dynamic matrix can be defined for the ``structure potential''. Its expectation value with respect to the vibrational modes increases nearly linearly with frequency and shows a clear indication of the boson peak. The structure eigenvectors of this dynamical matrix are strongly correlated to the vibrational ones. Four subgroups of modes can be distinguished

Identification of DNA binding proteins in vaccinia virus by DNA-protein crosslinking

AbstractDNA binding proteins of vaccinia virus (VV) virions, strain LIVP, have been studied by their covalent crosslinking to DNA, using two-dimensional gel retardation electrophoresis of crosslinked DNA and proteins as well as the ‘protein image’ hybridization assay. Five proteins with molecular masses of 16, 25, 27, 41 and 54 kDa, respectively, associated with all analysed DNA sequences, including early and late genes and their promoters, have been identified

Rapid Polarized Emission Variability of Blazar S5 0716+714 in Optical Range

© 2020, Pleiades Publishing, Ltd. Abstract—: The results of polarimetric observations of blazar S5 0716+714, carried out with the 6-meter BTA telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences, are presented. The polarized emission microvariability of blazar S5 0716+714 was observed in the R band with an initial time resolution of 3–5 seconds. Exposures were integrated at 1-minute intervals with a total observation time of several hours over two nights. Microvariability of the polarization degree with amplitude of 3–4% was detected during 7–11 minutes and flux oscillations within 9–10% during 25 minutes. A partial synchronism of the flux oscillations and the polarization degree of this blazar was found. Possible interpretations of the detected microvariability are briefly described