Spiral attractors as the root of a new type of "bursting activity" in the Rosenzweig-MacArthur model

We study the peculiarities of spiral attractors in the Rosenzweig-MacArthur model, that describes dynamics in a food chain "prey-predator-superpredator". It is well-known that spiral attractors having a "teacup" geometry are typical for this model at certain values of parameters for which the system can be considered as slow-fast system. We show that these attractors appear due to the Shilnikov scenario, the first step in which is associated with a supercritical Andronov-Hopf bifurcation and the last step leads to the appearance of a homoclinic attractor containing a homoclinic loop to a saddle-focus equilibrium with two-dimension unstable manifold. It is shown that the homoclinic spiral attractors together with the slow-fast behavior give rise to a new type of bursting activity in this system. Intervals of fast oscillations for such type of bursting alternate with slow motions of two types: small amplitude oscillations near a saddle-focus equilibrium and motions near a stable slow manifold of a fast subsystem. We demonstrate that such type of bursting activity can be either chaotic or regular

Herpes Simplex Virus Type 1 Clinical Isolates Respond to UL29-Targeted siRNA Swarm Treatment Independent of Their Acyclovir Sensitivity

Acyclovir is the drug of choice for the treatment of herpes simplex virus (HSV) infections. Acyclovir-resistant HSV strains may emerge, especially during long-term drug use, and subsequently cause difficult-to-treat exacerbations. Previously, we set up a novel treatment approach, based on enzymatically synthesized pools of siRNAs, or siRNA swarms. These swarms can cover kilobases-long target sequences, reducing the likelihood of resistance to treatment. Swarms targeting the UL29 essential gene of HSV-1 have demonstrated high efficacy against HSV-1 in vitro and in vivo. Here, we assessed the antiviral potential of a UL29 siRNA swarm against circulating strains of HSV-1, in comparison with acyclovir. All circulating strains were sensitive to both antivirals, with the half-maximal inhibitory concentrations (IC50) in the range of 350-1911 nM for acyclovir and 0.5-3 nM for the UL29 siRNA swarm. Additionally, we showed that an acyclovir-resistant HSV-1, devoid of thymidine kinase, is highly sensitive to UL29 siRNA treatment (IC50 1.0 nM; I-max 97%). Moreover, the detected minor variations in the RNAi target of the HSV strains had no effect on the potency or efficacy of UL29 siRNA swarm treatment. Our findings support the development of siRNA swarms for the treatment of HSV-1 infections, in order to circumvent any potential acyclovir resistance

CONCEPTUAL AND FRAME ORGANIZATION OF THE FAMILY OF WORDS WITH THE PEAK OF PR

The author of the article suggest a conceptual and frame approach to the description of a family of words. The author study the concept of PR. The concept of PR includes 114 derived words. All vocabulary is structured according to the levels of logical classification. The upper tier of the superframe includes semes: 1) the material world; 2) the organic world; 3) the person; 4) a person in society; 5) work activity rights. On the lower tier, we select 6 subframes: 1) action, PR activity; 2) association, the structure that carries out the activities of public relations; 3) characteristics, inherent, characteristic for PR; 4) event, PR event; 5) the situation of PR; 6) relations in the field of PR

Sequential switching activity in ensembles of inhibitory coupled oscillators

The heteroclinic cycles and channels are mathematical images of a sequential switching activity in neural ensembles. In this paper we present a phenomenological model of such activity. The model is based on coupled Poincaré systems. The existence of heteroclinic cycles and channels is shown

Characteristics of bifidobacteria biological properties in gut microflora disorders in HIV-infected children

Aim is to evaluate the biological properties of bifidobacteria in HIV-infected children with different degrees of gut microflora disorders to determine the direction for correction of bifidobacterium in HIV infection.Materials and methods. 58 selected cultures of bifidobacteria from HIV-infected children, 45 children in the comparison group. In bifidobacteria studied adhesion index of microorganisms (IAM), hydrophobicity (H), acid formation, antioxidant activity (AOA), delayed antagonism to opportunistic microorganisms.Results. In HIV-infected children at I degree of gut microflora disorders biological properties of bifidobacteria did not differ from the comparison group (p>0.05). At II degree of gut microflora disorders hydrophobicity of bifidobacteria was 45,75% (33; 58.8), IaM — 2.5 (2,0; 2.9), acid formation 67,30 T (53,0; 97,4), AOA — 0.8 Eaoa (0,6; 1.0). At III degree of gut microflora disorders H — 22,7% (15.8; 46,6), iAm — 2.4 (1,92; 3,69), acid formation — 66,3 T (48,9; 94,9), AOA-0.4 Eaoa (0,3; 0,6). Value biological properties at II and III degrees of gut microflora disorders were lower than in bifidoflora from HIV-negative children (p<0.01).Conclusion. At the I degree of gut microflora disorders in HIV infection it is necessary to correct the quantitative level of bifidobacteria. At II and III degree it is necessary to correct the surface properties, antioxidant and fermentation of carbohydrates activity of bifidobacteria