Chaos-hyperchaos transition in three identical quorum-sensing mean-field coupled ring oscillators.

We investigate the dynamics of three identical three-dimensional ring synthetic genetic oscillators (repressilators) located in different cells and indirectly globally coupled by quorum sensing whereby it is meant that a mechanism in which special signal molecules are produced that, after the fast diffusion mixing and partial dilution in the environment, activate the expression of a target gene, which is different from the gene responsible for their production. Even at low coupling strengths, quorum sensing stimulates the formation of a stable limit cycle, known in the literature as a rotating wave (all variables have identical waveforms shifted by one third of the period), which, at higher coupling strengths, converts to complex tori. Further torus evolution is traced up to its destruction to chaos and the appearance of hyperchaos.

Features of a chaotic attractor in a quasiperiodically driven nonlinear oscillator.

Transition to chaos via the destruction of a two-dimensional torus is studied numerically using an example of the Hénon map and the Toda oscillator under quasiperiodic forcing and also experimentally using an example of a quasi-periodically excited RL-diode circuit. A feature of chaotic dynamics in these systems is the fact that the chaotic attractor in them has an additional zero Lyapunov exponent, which strictly follows from the structure of mathematical models. In the process of research, the influence of feedback is studied, in which the frequency of one of the harmonics of external forcing becomes dependent on a dynamic variable.

Cascade of torus birth bifurcations and inverse cascade of Shilnikov attractors merging at the threshold of hyperchaos.

We study the hyperchaos formation scenario in the modified Anishchenko-Astakhov generator. The scenario is connected with the existence of sequence of secondary torus bifurcations of resonant cycles preceding the hyperchaos emergence. This bifurcation cascade leads to the birth of the hierarchy of saddle-focus cycles with a two-dimensional unstable manifold as well as of saddle hyperchaotic sets resulting from the period-doubling cascades of unstable resonant cycles.

Scenarios of hyperchaos occurrence in 4D Rössler system.

The generalized four-dimensional Rössler system is studied. Main bifurcation scenarios leading to a hyperchaos are described phenomenologically and their implementation in the model is demonstrated. In particular, we show that the formation of hyperchaotic invariant sets is related mainly to cascades (finite or infinite) of nondegenerate bifurcations of two types: period-doubling bifurcations of saddle cycles with a one-dimensional unstable invariant manifold and Neimark-Sacker bifurcations of stable cycles.

Evolution of quasiperiodicity in quorum-sensing coupled identical repressilators.

The dynamics of three three-dimensional repressilators globally coupled by a quorum sensing mechanism was numerically studied. This number (three) of coupled repressilators is sufficient to obtain such a set of self-consistent oscillation frequencies of signal molecules in the mean field that results in the appearance of self-organized quasiperiodicity and its complex evolution over wide areas of model parameters. Numerically analyzing the invariant curves as a function of coupling strength, we observed torus doubling, three torus arising via quasiperiodic Hopf bifurcation, the emergence of resonant cycles, and secondary Neimark-Sacker bifurcation.

Cooperative maintenance of cellular identity in systems with intercellular communication defects.

The cooperative dynamics of cellular populations emerging from the underlying interactions determines cellular functions and thereby their identity in tissues. Global deviations from this dynamics, on the other hand, reflect pathological conditions. However, how these conditions are stabilized from dysregulation on the level of the single entities is still unclear.

Coexistence between silent and bursting states in a biophysical Hodgkin-Huxley-type of model.

Classification of the dynamical mechanisms that support bistability between bursting oscillations and silence has not yet been clarified in detail. The purpose of this paper is to demonstrate that the coexistence of a stable equilibrium point with a state of continuous bursting can occur in a slightly modified, biophysical model that describe the dynamics of pancreatic beta-cells. To realize this form of coexistence, we have introduced an additional voltage-dependent potassium current that is activated in the region around the original, unstable equilibrium point.

[Biologically active substances in grated cocoa and cocoa butter].

In the article results of comparative analysis of grated cocoa and cocoa butter samples are presented. The investigation was done by modern instrumental methods such as HPLC, GC, UV- VIS-spectroscopy, and also with application of titrimetric and grarimetric methods. In the analyzed samples contents of total phenolics changes in an interval 1,0-3,2%, including monomeric proantocyanidins 0,6-1,35%; pyrroloquinoline quinine (PQQ) 0,34-0,76 microg/g; phenyl ethylamine from 2,79 to 14,97 microg/g, tyramine from 9,56 to 71,68 microg/g, dopamine from 5,3 to 25,85 microg/g; theobromine from 3,3 to 8%, caffeine from 0,49 to 0,70%; among the amino acids at the greatest quantities were presented glutaminic and asparaginic acids, arginin and leucin; three main fatty acids were determined - palmitinic (31+/-2% rel.

[Digital roentgenographic systems based on photostimulated screens and their comparison with roentgenographic screen-film sets].

Parameters of images obtained using roentgenographic systems based on stimulated luminophores (computer roentgenography) were experimentally compared. It was shown that roentgenography based on the use of stimulated luminophores had several advantages over conventional film roentgenography.

[Targeting and adjustment systems].

Various targeting and positioning systems based on ultrasonic and X-ray techniques are discussed. Specifications of four models of lithotrites are described. The advantages of online positioning are demonstrated.

[Effects of local vibration on development of ischemic heart disease in miners of South Kuzbas].

The incidence of ischemic heart disease (IHD) and risk factors of its genesis have been studied in 380 miners of a control group non-exposed to industrial vibration. Constitution type and a number of phenotypic signs have been determined for all examined workers with hemostatic indices defined in 60 miners before and after the performance of vibrational load test. High incidence of IHD, arterial hypertension and hyperholesterolemia have been detected in the miners working with vibration instruments and hemostatic disorders predisposing to ischemic heart disease have been revealed.

[Constitutional-morphologic features of coal miners exposed to vibration and suffering from coronary heart disease].

Occurrence of coronary heart disease and its risk factors are studied in individuals working with vibration instruments--in drift miners, miners of breakage face--and in 390 reference group miners who never faced occupational vibration. Findings are higher incidence of coronary heart disease, arterial hypertension and hypercholesterole mia in the miners working with vibration instruments. The main group miners suffering from coronary heart disease demonstrated more frequent hypersthenic constitutional type.

[Coronary heart disease, its risk factors and somatic types in coal miners having chronic dust-related diseases of lungs].

Studies covered incidence of coronary heart disease, its risk factors and features of constitutional types among Kouzbass coal miners suffering from anthracosilicosis and chronic dust bronchitis. Findings are reliably higher incidence of coronary heart disease among coal miners having lung diseases caused by dust. Coronary heart disease among the miners with anthracosilicosis is favored by arterial hypertension, overweight and hypersthenic constitutional type, that among those with dust bronchitis is favored only by overweight.

[X-ray diagnostic complexes Medix-R and Telemedix-R with digital image recording].

The paper outlines X-ray diagnostic sets made in Russia, whose modular principle allows one to choose the optimum price and quality delivery at different financing levels. The sets are equipped with up-to-date high-frequency X-ray image generators and intensifiers with a charge communication device-matrix as a television signal transducer.