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Dubkov A.,Lobachevsky State University of Nizhni Novgorod
Acta Physica Polonica B | Year: 2012

The stochastic Verhulst equation for the population density with fluctuating volume of resources is considered. Using the exact solution of this equation, the conditional probability density function is calculated for the excitation in the form of Lévy white noise with one-sided stable distribution. The phenomenon of transient bimodality and non-monotonic relaxation of mean population density for the white noise with Lévy-Smirnov stable distribution are found. An exact expression for the transitional time from bimodality to unimodality is obtained. It is interesting that for such a case the correlation function of population density in a steady state has a simple exponential form, and the correlation time does not depend on noise parameters.

Tokita M.,Lobachevsky State University of Nizhni Novgorod
Nanotechnologies in Russia | Year: 2015

This article describes recent trends in Spark Plasma Sintering (SPS) technology. The SPS method is widely recognized as a useful sintering technique to develop various kinds of attractive ceramics, metals, and composite materials due to its excellent features of rapid heating, electromagnetic field effect, and a well-controlled microstructure. © 2015, Pleiades Publishing, Ltd.

Fedoseev V.B.,Lobachevsky State University of Nizhni Novgorod
Physics of the Solid State | Year: 2015

Conditions for the formation and existence of stable and metastable thermodynamic states in a system with phase transformations have been considered. As the system decreases to nano- and submicron sizes, the degeneracy of the phase diagram in stratified mixtures is removed, due to which images of phase equilibria in the diagram has variants that substantially differ from the diagram of a macroscopic system by critical stratification temperatures, composition of coexisting solutions, and region of existence of metastable phases. This size effect is considered using the example of phase transformations in the Bi-Sb solid solution. © 2015, Pleiades Publishing, Ltd.

Dubkov A.A.,Lobachevsky State University of Nizhni Novgorod | Spagnolo B.,University of Palermo
European Physical Journal: Special Topics | Year: 2013

Using the method previously developed for ordinary Brownian diffusion, we derive a new formula to calculate the correlation time of stationary Lévy flights in a steep potential well. For the symmetric quartic potential, we obtain the exact expression of the correlation time of steady-state Lévy flights with index α = 1. The correlation time of stationary Lévy flights decreases with an increasing noise intensity and steepness of potential well. © 2013 EDP Sciences and Springer.

Chlorophyll and carotenoid content (ChCar), lipid peroxidation (LP) and growth parameters (GP) in plants are often used for environmental pollution estimation. However, the nonmonotonic dose-response dependences (hormesis and paradoxical effects) of these indices are insufficiently explored following exposure to different pollutants. In this experiment, we studied nonmonotonic changes in ChCar, LP, GP in wheat seedlings (Triticum aestivum L.) upon exposure to lead, cadmium, copper, manganese, formaldehyde, the herbicide glyphosate, and sodium chloride in a wide range from sublethal concentration to 102-105 times lower concentrations. 85.7% of dose-response dependences were nonmonotonic (of these, 5.5% were hormesis and paradoxical effects comprised 94.5%). Multiphasic dependences were the most widespread type of paradoxical effect. Hormesis was a part of some multiphasic responses (i.e. paradoxical effects), which indicates a relationship between these phenomena. Sublethal pollutant concentrations significantly increased LP (to 2.0-2.4 times, except for manganese and glyphosate) and decreased GP (to 2.1-36.6 times, except for glyphosate), while ChCar was reduced insignificantly, normalized or even increased. Lower pollutant concentrations caused a moderate deviation in all parameters from the control (not more than 62%) for hormesis and paradoxical effects. The seedling parameters could have different types of nonmonotonic responses upon exposure to the same pollutant. © 2014 University of Massachusetts.

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