Regular accelerating Universe without dark energy

Homogeneous isotropic cosmological models with two torsion functions filled with scalar fields and usual gravitating matter are built and investigated in the framework of the Poincar\'e gauge theory of gravity. It is shown that by certain restrictions on indefinite parameters of gravitational Lagrangian the cosmological equations at asymptotics contain an effective cosmological constant that can explain observable acceleration of cosmological expansion. The behavior of inflationary cosmological solutions at extremely high energy densities is analyzed, regular bouncing solutions are obtained. The role of the space-time torsion provoking the acceleration of cosmological expansion is discussed.Comment: 15 pages, 16 figures, iopart class file, some additions mad

Analysis of piece by piece methods of round wood measurements and volume estimation

Based on literature review piece by piece methods of round wood measurements employed in different countries are briefly discussed. The main working method of upper diameter (STB 1667-2012, GOST 2708–75) was researched (in comparison with the control data of formulas Smaliana and a truncated cone). An analysis of round wood volume tables from GOST 2708–75 in comparison with control data showed positive values of deviations that indicates larger values in standard volumes (GOST 2708–75) (up to 13% for medium-sized (24 cm) and large (over 24 cm) round wood). However, for logs with taper coefficient more than 1 cm/m) negative deviations are characterized, which, in turn, suggests an underestimation of wood volume in the standard tables in relation to the control data of formulas Smaliana and truncated cone (–18%). Formula Smaliana versus frustoconical formula underestimates the timber volume (however, not more than 1%). Obviously, both of these formulas can be used to determine the amount of measurement errors by the method of upper diameter. In our view, it is advisable to clarify the method of upper diameter based on the average value of taper coefficient in stacked batches of round wood (entering of amendments to the volumes from GOST 2708–75 on a log taper coefficient of real value)

Description of x-ray reflection and diffraction from periodical multilayers and superlattices by the eigenwave method

The analytical solution of recurrent equations for amplitudes of electromagnetic field is found for description of x-ray reflection and diffraction from periodical multilayered media. The method proposed uses the Bloch eigenwaves approach for periodical structure, which reduces considerably the computer time required for simulation of diffracted/reflected x-ray intensity and, therefore, accelerates the fitting trial-and-error procedure for sample model parameters. Numerical examples and fit results for experimental x-ray data are provided to demonstrate the effectiveness of method. A new parameter describing the fluctuation of superlattice period is introduced and its influence on experimental data interpretation is discussed

К 85-летию со дня рождения Ивана Никандровича Шестова

The information on activity of the Chair of the Dynamic Geology and Hydrogeology Department of the Perm State University, Dr. I.N. Shestov is presented.Приведены сведения о деятельности кандидата геолого-минералогических наук, доцента кафедры динамической геологии и гидрогеологии Пермского государственного национального исследовательского университета Ивана Никандровича Шестова

Nondestructive three-dimensional imaging of crystal strain and rotations in an extended bonded semiconductor heterostructure

International audienceWe report the 3D mapping of strain and tilts of crystal planes in an extended InP nanostructured layer bonded onto silicon, measured without sample preparation. Our approach takes advantages of 3D x-ray Bragg ptychography combined to an optimized inversion process. The excellent agreement with the sample nominal structure validates the reconstruction while the evidence of spatial fluctuations hardly observable by other means, underlines the specificities of Bragg ptychography