Non-minimal coupling influence on the deviation from de Sitter cosmological expansion

We investigate the models of cosmological inflation in generalized scalar-tensor gravity, which we consider as a source of deviation from de Sitter dynamics in the case of GR. Within the framework of the proposed approach, the exact equations of cosmological dynamics and parameters of cosmological perturbations are obtained.Comment: 14 page

The method of generating functions in exact scalar field cosmology

Exact solutions construction in scalar fields cosmology is of growing interest. In this work we review the results which obtained with the help of one of the most effective method. Namely, the method of generating functions for exact solutions construction in the scalar field cosmology. We also included into debate the superpotential method which may be considered as the bridge to slow roll approximation equations. Basing on the review, we suggested classification for the generating functions and found connection for all of them with the superpotential.Comment: 15 parge

Steering of Vortices by Magnetic Field Tilting in Open Superconductor Nanotubes

In planar superconductor thin films, the places of nucleation and arrangements of moving vortices are determined by structural defects. However, various applications of superconductors require reconfigurable steering of fluxons, which is hard to realize with geometrically predefined vortex pinning landscapes. Here, on the basis of the time-dependent Ginzburg–Landau equation, we present an approach for the steering of vortex chains and vortex jets in superconductor nanotubes containing a slit. The idea is based on the tilting of the magnetic field (Formula presented.) at an angle (Formula presented.) in the plane perpendicular to the axis of a nanotube carrying an azimuthal transport current. Namely, while at (Formula presented.), vortices move paraxially in opposite directions within each half-tube; an increase in (Formula presented.) displaces the areas with the close-to-maximum normal component (Formula presented.) to the close(opposite)-to-slit regions, giving rise to descending (ascending) branches in the induced-voltage frequency spectrum (Formula presented.). At lower B values, upon reaching the critical angle (Formula presented.), the close-to-slit vortex chains disappear, yielding (Formula presented.) of the (Formula presented.) type ((Formula presented.) : an integer; (Formula presented.) : the vortex nucleation frequency). At higher B values, (Formula presented.) is largely blurry because of multifurcations of vortex trajectories, leading to the coexistence of a vortex jet with two vortex chains at (Formula presented.). In addition to prospects for the tuning of GHz-frequency spectra and the steering of vortices as information bits, our findings lay the foundation for on-demand tuning of vortex arrangements in 3D superconductor membranes in tilted magnetic fields

Speckle dynamics under ergodicity breaking

Laser speckle contrast imaging (LSCI) is a well-known and versatile approach for the non-invasive visualization of flows and microcirculation localized in turbid scattering media, including biological tissues. In most conventional implementations of LSCI the ergodic regime is typically assumed valid. However, most composite turbid scattering media, especially biological tissues, are non-ergodic, containing a mixture of dynamic and static centers of light scattering. In the current study, we examined the speckle contrast in different dynamic conditions with the aim of assessing limitations in the quantitative interpretation of speckle contrast images. Based on a simple phenomenological approach, we introduced a coefficient of speckle dynamics to quantitatively assess the ratio of the dynamic part of a scattering medium to the static one. The introduced coefficient allows one to distinguish real changes in motion from the mere appearance of static components in the field of view. As examples of systems with static/dynamic transitions, thawing and heating of Intralipid samples were studied by the LSCI approach

Reconstruction of Scalar-Torsion Gravity Theories from the Physical Potential of a Scalar Field

We consider scalar-torsion gravity theories based on the exact solutions of a physical type of potential for cosmological inflationary models based on the non-minimal coupling of a scalar field and torsion. We analyzed the inflationary models with different types of inflationary dynamics and corresponding scalar field parameters. Such an approach allows us to consider different physical potentials and types of scalar-torsion gravity theories in the context of the realization of both stages of accelerated expansion of the universe. We also considered the correspondence surrounding the proposed inflationary models and the observational constraints on the parameters of cosmological perturbations

Relic gravitational waves in verified inflationary models based on the generalized scalar–tensor gravity

In this work, we consider the models of cosmological inflation based on generalized scalar–tensor theories of gravity with quadratic connection between the Hubble parameter and coupling function. For such a class of the models, we discuss the correspondence between well-known versions of the scalar–tensor gravity theories and physically motivated potentials of a scalar field. It is shown that this class of models corresponds to the Planck observational constraints on the cosmological perturbation parameters for an arbitrary potential of a scalar field and arbitrary version of a scalar–tensor gravity theory. The spectrum of relict gravitational waves is analyzed, and the frequency range corresponding to maximal energy density is determined. The possibility of direct detection of the relic gravitational waves, predicted in such a class of models, by satellite and ground-based detectors is discussed as well