Torus breakdown in noninvertible maps.

We propose a criterion for the destruction of a two-dimensional torus through the formation of an infinite set of cusp points on the closed invariant curves defining the resonance torus. This mechanism is specific to noninvertible maps. The cusp points arise when the tangent to the torus at the point of intersection with the critical curve L(0) coincides with the eigendirection corresponding to vanishing eigenvalue for the noninvertible map. Further parameter changes lead typically to the generation of loops (self-intersections of the invariant manifolds) followed by the transformation of the torus into a complex chaotic set.

Influence of the nature of the pasting liquid on the accumulation of nitroanilines at carbon paste electrode during determination by absorptive stripping voltammetry.

ABSTRACT. The accumulation of ortho-, para-nitroanilines, 2,4-dimetyl-6-nitroaniline, and meta-nitrobenzoic acid at carbon paste electrode (CPE) has been studied. For the preparation of CPE different pasting liquids have been used: esters, aromatic hydrocarbons, saturated hydrocarbons, and polymethylsiloxane. Distribution ratios of o- and p-nitroanilines between the pasting liquid and water have been determined. Correlation between peak current constants and distribution ratios has been found. It has been demonstrated that during the determination of analyte on the CPE with aromatic hydrocarbons, the main influence on nitro-compound accumulation is executed by the extraction into the pasting liquids, and on the CPE with saturated hydrocarbons - by the process of depolarizer sorption onto the graphite. The selective determination of nitroanilines in the presence of hindering compounds with adsorptive stripping voltammetry has been carried out.

Desynchronization of chaos in coupled logistic maps.

When identical chaotic oscillators interact, a state of complete or partial synchronization may be attained in which the motion is restricted to an invariant manifold of lower dimension than the full phase space. Riddling of the basin of attraction arises when particular orbits embedded in the synchronized chaotic state become transversely unstable while the state remains attracting on the average. Considering a system of two coupled logistic maps, we show that the transition to riddling will be soft or hard, depending on whether the first orbit to lose its transverse stability undergoes a supercritical or subcritical bifurcation. A subcritical bifurcation can lead directly to global riddling of the basin of attraction for the synchronized chaotic state. A supercritical bifurcation, on the other hand, is associated with the formation of a so-called mixed absorbing area that stretches along the synchronized chaotic state, and from which trajectories cannot escape. This gives rise to locally riddled basins of attraction. We present three different scenarios for the onset of riddling and for the subsequent transformations of the basins of attraction. Each scenario is described by following the type and location of the relevant asynchronous cycles, and determining their stable and unstable invariant manifolds. One scenario involves a contact bifurcation between the boundary of the basin of attraction and the absorbing area. Another scenario involves a long and interesting series of bifurcations starting with the stabilization of the asynchronous cycle produced in the riddling bifurcation and ending in a boundary crisis where the stability of an asynchronous chaotic state is destroyed. Finally, a phase diagram is presented to illustrate the parameter values at which the various transitions occur.

[The use of ground mollusks in the evaluation of environmental pollution with heavy metals in the city of Ufa]. / Primenenie nazemnykh molluskov dlia otsenki zagriazneniia territorii g. Ufy tiazhelymi metallami.

The authors analyzed soil and cochleae of bush snails in Ufa for heavy metals (Zn, Cu, Pb, Cd) content. Zn and Cu content of the soil exceeds the background levels and approaches the MACs. Pb and Cd content corresponds to their usual content of soil. The coefficients of Zn, Cu, Pb and Cd pass from soil to cochleae of bush snails increase in the row Pb < Zn < Cu < Cd and never outnumber 1.

[Concentration of imidazolines in the air]. / Kontsentrirovanie imidazolinov iz vozdukha.

Using chamber for adjustable mode and dosing apparatus, the authors studied conditions of imidazolines' condensation from the air into 60% ethanol, to paper filters of "white tape" type, to analytic filters of AFA-HP type, into a shell with ultrathin layer of sorbent (2.7% sulfuric acid in 20% solution of glycerine in water). The best results were provided by experiments using the paper filter of "white tape" type and absorbing objects filled with 60% ethanol and containing spongy plate. Rate of the air pumping equalled 2-3 l/min and 0.5 l/min respectively.

[Mutagenesis, directed by artificial oligonucleotide analogs. I. Participation of ribonucleotide fragments in DNA replication and repair]. / Mutagenez, napravlennyi neprirodnymi analogami oligonukleotidov. I. Uchastie ribonukleotidnykh zven'ev v reparatsii i replikatsii DNK.

The mutation system has been developed to study the mutagenic properties of modified oligonucleotide analogs. The mutagenic properties of oligonucleotides containing one ribonucleotide have been examined. The presence of a ribonucleotide is shown not to induce any mutations. But when the oligonucleotide induces two marker deletions detached by 6 nucleotides they may be repaired separately, in this case the deletion bordering with the ribonucleotide is predominantly repaired.

[Substrate specificity of T4 RNA-ligase. The effect of the nucleotide sequence of the minimum phosphate acceptor on the efficacy of intermolecular ligation]. / Substratnaia spetsifichnost' RNK-ligazy T4. Vliianie nukleotidnoi posledovatel'nosti minimal'nogo aktseptora fosfata na éffektivnost' mezhmolekuliarnogo ligirovaniia.

The 2' (3'),5'-diphosphates of cytidine, uridine, adenosine and the trinucleoside diphosphates, such as NpCpC, NpCpU, NpUpC, NpUpU and ApNpC (where N = U, C, A, G), were used to study the substrate specificity of the T4 RNA ligase. The outcome of ligating various phosphate acceptors to a common phosphate donor was governed not only by nucleotide composition but also the nucleotide sequence of a phosphate acceptor. The effect of the changes in a single position of the phosphate acceptor on the efficiency of the intermolecular ligation cannot be defined independently of the other nucleotide residues. For four examined groups of phosphate acceptors and pCp as a donor, four different ranks were obtained (in order of decreasing reactivity): C greater than A greater than greater than U greater than G (for NpCpC); G greater than U approximately equal to A greater than C (NpCpU); A greater than U greater than C greater than G (NpUpC) and A greater than G greater than C greater than U (NpUpU). The yield of ligation products with various phosphate donors and a common phosphate acceptor significantly depends on the donor structure: pyrimidine phosphate donors are more effective than pAp, while pCp is more effective than pUp.

[Isolation of highly purified RNA ligase from bacteriophage T4]. / Vydelenie vysokoochishchennoi RNK-ligazy bakteriofaga T4.

A technique for isolation of RNA-ligase of bacteriophage T4 was proposed. It is mainly based on the using of Soviet materials and sorbents and includes seven purification stages. The technique enables to isolate about 80 000 units of active enzyme from 100 g of E. coli B cells infected with the phage. T4am N82; that makes up 20% of the activity of the cell extract. The obtained preparations of RNA-ligase are homogeneous by the data of electrophoresis and practically, free of endo- and exonuclease admixtures.

[Restoration of enzyme induction, reduced as a result of long-term cortisol administration, in rat liver]. / Vosstanovlenie fermentativnoi induktsii, snizhennoi v rezul'tate dlitel'nogo vvedeniia kortizola, v pecheni krys.

Restoration of tyrosinamine transferase (TAT) with cortisol in the rat hepatocytes after the cessation of prolonged (for many days) administration of this hormone was investigated. The effect of the liver regeneration and insulin administration on this process was also studied. In single cortisol administration the TAT activity rose 5-fold; the induction response decreased after 21 days of daily administration. The TAT induction in response to cortisol administration was restored completely only on the 25th--30th day after the cessation of this hormone injection. A three-day insulin administration led to the restoration of TAT induction in response to cortisol administration. The process of the liver regeneration during the first 24 hours after partial hepatectomy induced TAT in the cells of both control animals and those given cortisol for prolonged periods; besides, it aided restoration of the induction response to cortisol administration.