Parameters of ecosystem and interaction of man and nature in sand deserts during different prehistorical periods

The ecology and demography of ancient societies have created much current interest in natural-scientific and historical-archaeological investigations. The problem of palaeoclimatic changes, based on data from soil science (LV. Ivanov, V.A. Demkin, A.L. Alexandrovsky) and palynology (N.S. Bolikhovskaya, K.K. Kremenetsky, Ye.A. Spiridonova) in the steppe zone during different archaeological periods is still only partially understood. At the same time, progress achieved in studying modern ecosystems and establishing certain correlations between their components make it possible to reconstruct the basic parameters of the past, namely the phytoproduction of the ground, phytomass used and the number of wild mammals

Hopping Conductivity and Negative Magnetoresistance of the Bulk Nanograined Bi2Te3 Material

The bulk nanograined Bi2Te3 material was prepared by the microwave assisted solvothermal method and cold isostatic pressure method. It was found that above T* ≈ 190 K the temperature dependence of the specific electrical resistivity of material is of metallic type, while below this temperature a semiconductor conductivity takes place. Within the temperature ΔT ≈ 90 K-35 K interval the electrical conductivity of material can be described by the variable-range hopping conductivity mechanism. Negative magnetoresistance was observed at the same temperature interval

Age-Specific And Sexual Variability Of Morphological And Biomechanical Parameters Of Anterior Cerebral Artery Of Adults

In the experiment on monoaxonic longitudinal distension by tensile-testing machine Tira Test 28005 (Germany) with loading unit - 100 N the general rigidity, breaking point and relative lengthening of anterior cerebral artery (АСА) of adult people have been under study. Under the microscope on transverse sections the external diameter of the artery, its wall thickness have been measured and diameter of lumen have been calculated. In total 228 АСА (132 - from corpses of men, 92-from corpses of women) have been investigated. They have been received in 16 hours after autopsy of adult people whose cause of death has not been connected with vascular cerebral pathology. It has been revealed that right АСА is longer and narrower than left one. ACA's wall length and thickness predominate in men in comparison with women in average of 5,4 - 13,0%. With years АСА lengthens, its external diameter increases. Biomechanical parameters of ACA's wall do not have any authentic sexual differences, they don't depend on the side of the arterial ring. With years the rigidity of АСА decreases, especially in middle age. In old age its general rigidity increases. It is connected with the increase of ACA's wall thickness. The ability of АСА to lengthening doesn't depend upon age. Experimental findings may be used as criteria of age standard of morphological and biomechanical parameters of АС

Parameter estimators of nonlinear quantile regression

We have obtained the asymptotic normality of parameter estimators of a nonlinear quantile regression with nonsymmetric random noise

Consistency of M-estimates in general nonlinear regression models

Nonlinear regression model with continuous time and weak dependent or long-range dependent stationary noise is considered. Strong consistency suffient conditions of M-estimates of regression parameters are obtained

Analysis of Arc Processes in Multi-chamber Arrester for Lightning Protection at High-voltage Overhead Power Lines

Nowadays multi-chamber arresters are widely distributed as devices of lightning protection of overhead power lines. A mathematical modelling of processes in the discharge chamber of multichamber arrester is necessary to carry out in order to improve its breaking capacity. A three-dimensional mathematical transient model of thermal, gas-dynamic and electromagnetic processes taking place in the discharge chamber of multi-chamber arrester is presented in the article. Basic assumptions, model equations, a computational domain and the boundary conditions are described. Plasma turbulence is taken into account. The results of the calculation i.e. distributions of plasma temperature and overpressure in the discharge chamber at different time points are shown. The analysis of the results was carried out. It is shown that the presence of cavities in the electrodes design promotes electric arc extinction in the discharge chamber of multi-chamber arrester

Gauge invariance, causality and gluonic poles

We explore the electromagnetic gauge invariance of the hadron tensor of the Drell-Yan process with one transversely polarized hadron. The special role is played by the contour gauge for gluon fields. The prescription for the gluonic pole in the twist 3 correlator is related to causality property and compared with the prescriptions for exclusive hard processes. As a result of we get the extra contributions, which naively do not have an imaginary phase. The single spin asymmetry for the Drell-Yan process is enhanced by the factor of two.Comment: 9 pages, 2 figures; References and acknowledgements added

Coulomb Correlations and Magnetic Anisotropy in ordered L10L1_0 CoPt and FePt alloys

We present results of the magneto-crystalline anisotropy energy (MAE) calculations for chemically ordered $L1_0$ CoPt and FePt alloys taking into account the effects of strong electronic correlations and spin-orbit coupling. The local spin density + Hubbard U approximation (LSDA+U) is shown to provide a consistent picture of the magnetic ground state properties when intra-atomic Coulomb correlations are included for both 3$d$ and 5$d$ elements. Our results demonstrate significant and complex contribution of correlation effects to large MAE of these material.Comment: revised version; 4 pages, 2 figure

On the choice of heavy baryon currents in the relativistic three-quark model

We test the sensitivity of bottom baryon observables with regard to the choice of the interpolating three-quark currents within the relativistic three-quark model. We have found that the semileptonic decay rates are clearly affected by the choice of currents, whereas the asymmetry parameters show only a very weak dependence on the choice of current.Comment: revtex, 9 page

Hydrodynamic Features of Gas-Liquid Flow Movement in a Separation Device Plane Channel with an Oscillating Wall

In this paper, the movement of a gas-fluid flow in a plane channel with an oscillating wall was investigated. The aim of the research is to increase the efficiency of separation equipment by imposing the vibration impact on a gas-liquid flow. This purpose was achieved by applying the phenomenon of selective coagulation of a dropping liquid. The novelty of the proposed ap-proach concerns creating the mathematical model for determination of analytical dependences between the efficiency of the hydromechanical process and initial parameters of the separation device. As a result, quantitatively and qualitatively sufficient approximations for the scalar pres-sure and vector velocity fields were obtained with a permissible relative error in comparison with the results of numerical simulation. The presence of biharmonic fluctuation of particles was proved; besides, related dependencies for the calculation of vibration characteristics were ob-tained. Additionally, the paper presents the dependencies for identifying a range of thickness for a near-wall area. The system of dimensionless criteria was proposed for determining flow modes and relative trajectories of liquid droplets in a gas-fluid flow. The numerical simulation approach and related methodology of engineering calculations were proposed on the example of a plane channel of the separation device. Finally, the distance between adjacent zones of the pressure minimum was determined. As a result, it was found that this distance is equal to the wavelength of the vibrating impact to the flow that is an initial justification of further coagulation process of liquid droplets in a gas-liquid flow in a separation device