Scattering anisotropy of cellular cultures of leukemia lines in the THz frequency range

The scattering anisotropy factors of splenocytes, thymocytes, and several leukemia cellular lines have been measured. It is shown that the scattering anisotropy factors of leukemia cellular lines exceed several times those of normal cells.     

Copolymers of 2-deoxy-2-methacrylamido-D-glucose and unsaturated acids

New copolymers of the vinyl saccharide 2-deoxy-2-methacrylamido-D-glucose (M₁) with acrylic and methacrylic (M₂) acids differing in composition and molecular mass have been synthesized by free-radical copolymerization. The relative activities of the comonomers are determined. It is found that, for acrylic acid, r ₁ = 3.03 ± 0.15 and r ₂ = 0.5 ± 0.08 and, for methacrylic acid, r ₁ = 1.070 ± 0.1 and r ₂ = 1.18 ± 0.13. As is evidenced by potentiometric and viscometric measurements, the vinyl saccharide and acid units are capable of interacting, a circumstance that affects the conformational states of macromolecules.     

Passages through resonance in weakly nonlinear systems

A method of determining asymptotic expansions for weakly couplednonlinearly perturbed systems of harmonic oscillators with slowlyvarying frequencies is presented. In an example with two oscillators,each one experiences a separate resonance passage that producesa first-order amplitude change. Simultaneously, second-orderadjustments occur to both oscillators. The determination isachieved by carrying the calculations to third order.     

ON THE IMPULSIVE BEVERTON–HOLT EQUATION AND EXTINCTION CONDITIONS IN POPULATION DYNAMICS

Abstract This paper is devoted to investigate extinction and nonextinction conditions of the extended Beverton–Holt equation (BHE) for dynamics of populations in Ecology when potential discontinuities at sampling points are included in the model. The proposed model is described by means of four sequences of parameters. Two of them are the intrinsic growth rate and the carrying capacity sequences which are included in the basic BHE model. The other two ones, namely, the harvesting (i.e., the hunting or fishing quota) and the internal consumption (which can include positive and negative migrations in the considered population habitat) sequences are included to parameterize the model discontinuities. Such discontinuities are related to impulses in the corresponding continuous‐time logistic equation. The obtained results establish how the harvesting quota and/or the internal consumption has to be fixed to guarantee the population nonextinction or, eventually, its extinction. Finally, some controllability results related to the search of a carrying capacity sequence such that the solution of the proposed impulsive BHE tracks a reference one are obtained.     

Morphological phase diagram of a spherical crystal growing under nonequilibrium conditions at the growth rate as a quadratic function of supersaturation

The complete morphological diagram of a spherical nucleus growing from a solution under nonequilibrium conditions at a local growth rate as a quadratic function of supersaturation is calculated for the first time on the basis of a linear analysis for morphological stability and the principle of maximum entropy production. The results of calculations are compared with those obtained previously for a spherical particle in the case of a linear dependence of the growth rate on the supersaturation.     

Resonance interaction of an edge-dislocation wall with a traveling sound wave

The dynamics of an infinite edge-dislocation wall and fragments of this wall in their interaction with a monochromatic sound wave with a nonzero wave vector has been investigated taking into account the mass of dislocations. It has been shown that the drift velocities of the wall fragments significantly increase when the sound wave frequency approaches the natural frequencies of small-amplitude vibrations, including zero frequency. For the infinite wall, a similar increase in the drift velocity is observed for low frequencies and for frequencies close to half the maximum frequency of small-amplitude vibrations of the edge-dislocation wall. The resonance increase in the drift velocity at low frequencies of the sound wave can be important for practical applications.