Electron Mass Operator in a Strong Magnetic Field and Dynamical Chiral Symmetry Breaking

The electron mass operator in a strong magnetic field is calculated. The contribution of higher Landau levels of virtual electrons, along with the ground Landau level, is shown to be essential in the leading log approximation. The effect of the electron dynamical mass generation by a magnetic field is investigated. In a model with N charged fermions, it is shown that some critical number N_{cr} exists for any value of the electromagnetic coupling constant alpha, such that the fermion dynamical mass is generated with a doublet splitting for N < N_{cr}, and the dynamical mass does not arise at all for N > N_{cr}, thus leaving the chiral symmetry unbroken.Comment: 4 pages, REVTEX4, 3 figure

Electron mass operator in a strong magnetic field

The electron mass operator in a strong magnetic field is calculated by summation of the leading log contributions in all orders of the perturbation theory. An influence of the strong field on the virtual photon polarization operator is taken into account. The contribution of higher Landau levels of virtual electrons, along with the ground Landau level, is shown to be essential in the leading log approximation.Comment: 7 pages, LATEX, 1 PS figure, submitted to Modern Physics Letters

Study of Viscosity-temperature Properties of Oil and Gas-condensate Mixtures in Critical Temperature Ranges of Phase Transitions

Transport of oil and gas-condensate mixtures of various compositions is found to be accompanied by a slight increase in viscosity in the coldest period when ground temperatures at depth of a condensate pipeline reach 0 – minus 4°С. Fall in temperature of oil fluids under study to minus 10 – minus 30°С is accompanied by a sharp increase in all structural and rheological parameters of the mixture. Even a slight amount of oil added to a gas-condensate mixture causes a significant decrease in viscosity in the negative temperature range. As a result, cloud and pour point of a mixture falls, its amount decreases, the structure of paraffin deposits changes

Polarization change due to fast winds from accretion disks

A fraction of the radiation produced by an accretion disk may be Thomson scattered by a wind flowing away from the disk. Employing a simple plane-parallel model of the wind, we calculate the polarization of the scattered radiation and find that its sign depends on the wind velocity, beta=v/c. In the case, 0.12 < beta < 0.78, the polarization is parallel to the disk normal, i.e., it is orthogonal to the standard Chandrasekhar's polarization expected from accretion disks. The velocity of an electron-positron wind is likely to saturate near the equilibrium value beta_* of order 0.5 for which the accelerating radiation pressure is balanced by the Compton drag. Then the change of polarization by the wind is most pronounced. This may help to reconcile the standard accretion disk model with the optical polarimetric observations of non-blazar AGNs.Comment: accepted for publication in ApJ Letter

On the anniversary of Academician of the Russian Academy of Sciences Olga Silvestrovna Afanasenko

In December 2023, the leading mycologist-phytopathologist of the Russian Federation, head of the laboratory of plant immunity to diseases of the All-Russian Research Institute of Plant Protection (VIZR), Doctor of Biological Sciences, Professor, Academician of the Russian Academy of Sciences Olga Silvestrovna Afanasenko celebrates her anniversary. The main direction of O.S. Afanasenko’s work is a comprehensive study of the mechanisms of variability in populations of phytopathogenic fungi, race-forming processes and interorganismal genetics in the pathosystems “cereal crops - hemibiotrophic pathogens”. In cooperation with colleagues from VIR, as well as from specialized institutions of the Russian Federation and foreign countries, research is being carried out to identify genes for resistance of grain crops to the most harmful pathogens

Breeding value of european oat accessions in the environments of Kuban experiment station of VIR

Background. For the present-day oat breeding, the task is to develop adaptive cultivars with high yield potential, high quality of products, fairly early-ripening habit, and resistance to lodging and diseases. Breeding new cultivars with a complex of valuable characters, high yield, and high quality of products under varied environmental conditions requires well-studied source material. Selection of sources according to the basic economically useful traits is one of the main objectives in the study of the global diversity preserved in the oat collection.Results and conclusion. The article presents the results of studying the oat accessions from Western and Central European countries, preserved in the VIR collection, under the conditions of Kuban Experimental Station of VIR (Krasnodar Terr.). Evaluation of the accessions in the field was targeted at such crop characters as the duration of the growing season, resistance to lodging, and field resistance to rust diseases. A structural analysis was performed in the laboratory to measure the weight of 1000 grains, the number of spikelets and grains per panicle, grain weight per panicle and per plant, and percentage of grain hullness. As a result of a three-year comprehensive field study of the newest oat cultivars bred in Western Europe in the environments of Kuban Experimental Station of VIR, sources of traits useful for breeding were identified, such as lodging resistance, field resistance to crown rust, high yield structure components (1000 grain weight, grain weight per panicle, number of grains per panicle, grain productivity). When using source materials in oat breeding practice, in addition to economically important traits, special attention should be paid to grain size, since this character, according to our data, has the most significant correlation with the grain yield of a cultivar. The identified sources of traits valuable for breeding may be included in breeding programs of Krasnodar Territory and other regions of the Russian Federation

Classical motion in force fields with short range correlations

We study the long time motion of fast particles moving through time-dependent random force fields with correlations that decay rapidly in space, but not necessarily in time. The time dependence of the averaged kinetic energy and mean-squared displacement is shown to exhibit a large degree of universality; it depends only on whether the force is, or is not, a gradient vector field. When it is, p^{2}(t) ~ t^{2/5} independently of the details of the potential and of the space dimension. Motion is then superballistic in one dimension, with q^{2}(t) ~ t^{12/5}, and ballistic in higher dimensions, with q^{2}(t) ~ t^{2}. These predictions are supported by numerical results in one and two dimensions. For force fields not obtained from a potential field, the power laws are different: p^{2}(t) ~ t^{2/3} and q^{2}(t) ~ t^{8/3} in all dimensions d\geq 1

Concentration dependences of solvent self-diffusion coefficients in solutions and heterogeneous systems

On the basis of the concepts of exchange processes the problem to interpret solvent self-diffusion coefficients measured by pulsed field gradient nuclear magnetic resonance in solutions of various nature and heterogeneous systems is discussed. The problem to choose the concentration scale for the interpretation of the concentration dependences of self-diffusion coefficients in such systems is discussed as well. © Springer-Verlag 2005

Bouncing trimer: a random self-propelled particle, chaos and periodical motions

A trimer is an object composed of three centimetrical stainless steel beads equally distant and is predestined to show richer behaviours than the bouncing ball or the bouncing dimer. The rigid trimer has been placed on a plate of a electromagnetic shaker and has been vertically vibrated according to a sinusoidal signal. The horizontal translational and rotational motions of the trimer have been recorded for a range of frequencies between 25 and 100 Hz while the amplitude of the forcing vibration was tuned for obtaining maximal acceleration of the plate up to 10 times the gravity. Several modes have been detected like e.g. rotational and pure translational motions. These modes are found at determined accelerations of the plate and do not depend on the frequency. By recording the time delays between two successive contacts when the frequency and the amplitude are fixed, a mapping of the bouncing regime has been constructed and compared to that of the dimer and the bouncing ball. Period-2 and period-3 orbits have been experimentally observed. In these modes, according to observations, the contact between the trimer and the plate is persistent between two successive jumps. This persistence erases the memory of the jump preceding the contact. A model is proposed and allows to explain the values of the particular accelerations for which period-2 and period-3 modes are observed. Finally, numerical simulations allow to reproduce the experimental results. That allows to conclude that the friction between the beads and the plate is the major dissipative process.Comment: 22 pages, 10 figure

Stochastic Nonlinear Programming System

This paper contains a detailed description of the Stochastic Nonlinear Programming System (SNLP) intended for solving stochastic optimization problems with simple recourse. This system is a result of collaboration between the Glushkov Institute of Cybernetics (Kiev, USSR) and the International Institute for Applied System Analysis (IIASA) within the framework of the Adaptation and Optimization Project in the System and Decision Sciences Program