The bacterial chemotaxis in a one-dimensional system with a repellent has been considered. The process of bacterial redistribution in the system is analyzed, and a corresponding phenomenological model is proposed, which makes allowance for the diffusion of bacteria and their motion caused by the repellent gradient. The repellent injection into the system is governed by boundary conditions. In the framework of this model, the chemotaxis sensitivity function, a numerical characteristic, which describes the nonuniformity in the bacterial distribution, is calculated. A dependence of the chemotaxis sensitivity function on the repellent concentration at the system boundaries is obtained. A relation between the bacterial distribution and the parameters of repellent distribution is found.

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Thermodynamic properties of a system of an interacting boson particles and antiparticles at high tem­peratures are studied within the framework of the thermodynamically consistent Skyrme-­like mean-­field model. The mean field contains both attractive and repulsive terms. Self­-consistency relations between the mean field and thermodynamic functions are derived. We assume a conservation of the isospin density for all temperatures. It is shown that, independently of the strength of the attractive mean field, at the critical tem­perature Tc the system undergoes the phase transition of second order to the Bose­-Einstein condensate, which exists in the temperature interval 0 ≤ T ≤ Tc . It is obtained that the condensation represents a discontinuity of the derivative of the specific heat at T = Tc .