Devil's staircase and the absence of chaos in the dc- and ac-driven overdamped Frenkel-Kontorova model.

The devil's staircase structure arising from the complete mode locking of an entirely nonchaotic system, the overdamped dc+ac driven Frenkel-Kontorova model with deformable substrate potential, was observed. Even though no chaos was found, a hierarchical ordering of the Shapiro steps was made possible through the use of a previously introduced continued fraction formula. The absence of chaos, deduced here from Lyapunov exponent analyses, can be attributed to the overdamped character and the Middleton no-passing rule. A comparative analysis of a one-dimensional stack of Josephson junctions confirmed the disappearance of chaos with increasing dissipation. Other common dynamic features were also identified through this comparison. A detailed analysis of the amplitude dependence of the Shapiro steps revealed that only for the case of a purely sinusoidal substrate potential did the relative sizes of the steps follow a Farey sequence. For nonsinusoidal (deformed) potentials, the symmetry of the Stern-Brocot tree, depicting all members of particular Farey sequence, was seen to be increasingly broken, with certain steps being more prominent and their relative sizes not following the Farey rule.

Reaction of Lymphoid Organs to Injection of Iron-Carbon Nanoparticles.

The distribution of iron-carbon nanoparticles in FeC-DSPE-PEG-2000 modification (micellar particles with structure (Fe) core-carbon shell; PEG-based coating) is studied. The greater part of the nanoparticles accumulated in the spleen and liver, a small amount in the lungs, and the minimum amount in the thymus. The structural changes in the lymphoid organs were minor and involved only the microcirculatory bed. Analysis of the peripheral blood showed manifest anemia, thrombocytopenia, and leukocytosis.

[The influence of low-frequency pulsed electric and magnetic signals or their combination on the normal and modified fibroblasts (an experimental study)]. / Vliyanie nizkochastotnykh impul'snykh elektricheskogo, magnitnogo signalov i ikh sochetaniya na normal'nye i transformirovannye fibroblasty (eksperimental'noe issledovanie).

The results of clinical studies give evidence of the beneficial preventive and therapeutic effects of the «Tiline-EM¼ physiotherapeutic device designed for the combined specific treatment of the skin regions onto which both discomfort and pain sensations are directly projected, reflectively active sites and zones, as well as trigger zones with the use of low-frequency pulsed electric current and magnetic field. The efficient application of the device requires the understanding of the general mechanisms underlying such action on the living systems including those operating at the cellular and subcellular levels. The objective of the present study was the investigation of the specific and complex effects produced by the low-frequency pulses of electric current and magnetic field generated in the physiotherapeutic device «Tiline-EM¼ on the viability, proliferative activity, and morphofunctional characteristics of normal skin fibroblasts and the transformed fibroblast line K-22. It has been demonstrated that the biological effects of the electric and magnetic signals vary depending on the type of the cell culture and the mode of impact. The transformed fibroblasts proved to be more sensitive to the specific and complex effects of electric and magnetic pulses than the normal skin fibroblasts. The combined action of the electric and magnetic signals was shown to have the greatest influence on both varieties of fibroblasts. It manifests itself in the form of enhanced viability, elevated proliferative and synthetic activity in the cultures of transformed fibroblasts and as the acceleration of cell differentiation in the cultures of normal fibroblasts. The effect of stimulation of dermal fibroblast differentiation in response to the combined treatment by the electric and magnetic signals is of interest from the standpoint of the physiotherapeutic use of the «Tiline-EM¼ device for the purpose of obtaining fibroblasts cultures to be employed in regenerative therapy and the treatment of skin injuries in cosmetology, aesthetic and regenerative medicine.

Evaluation of Biodistribution of Functionalized Magnetic Core/Carbon-Shell Nanoparticles in Systemic Method of Administration.

We studied new magnetic nanocomposites consisting of a core(Fe) and carbon-shell inert to biological media. Iron-carbon nanoparticles circulate in the bloodstream for several minutes and are primarily accumulated in the liver; less intensive accumulation was found in the spleen and minimum in the lungs, kidneys, and heart. Accumulation of nanoparticles in the liver leads to the development of destructive processes and is accompanied by activation of compensatory-adaptive mechanisms. In the liver and spleen, structural changes are mild and mainly relate to changes in the microvasculature. In 6 months, the total content of nanoparticles in all tissues decreased due to their elimination from the body and the structure of the organs returned to normal.

Structured chaos in a devil's staircase of the Josephson junction.

The phase dynamics of Josephson junctions (JJs) under external electromagnetic radiation is studied through numerical simulations. Current-voltage characteristics, Lyapunov exponents, and Poincaré sections are analyzed in detail. It is found that the subharmonic Shapiro steps at certain parameters are separated by structured chaotic windows. By performing a linear regression on the linear part of the data, a fractal dimension of D = 0.868 is obtained, with an uncertainty of ±0.012. The chaotic regions exhibit scaling similarity, and it is shown that the devil's staircase of the system can form a backbone that unifies and explains the highly correlated and structured chaotic behavior. These features suggest a system possessing multiple complete devil's staircases. The onset of chaos for subharmonic steps occurs through the Feigenbaum period doubling scenario. Universality in the sequence of periodic windows is also demonstrated. Finally, the influence of the radiation and JJ parameters on the structured chaos is investigated, and it is concluded that the structured chaos is a stable formation over a wide range of parameter values.