Second harmonic generation in suspensions of spherical particles

We study the second harmonic generation (SHG) in a suspension of small spherical particles confined within a slab, assuming undepleted pump and applying (i) single scattering approximation and (ii) diffusion approximation. In the case (i), the angular diagram, the differential and total crossections of the SHG process, as well as the average cosine of SH scattering angle are calculated. In the case (ii), the average SH intensity is found to show no explicit dependence on the linear scattering properties of the suspension. The average intensity of SH wave scales as I_0 L / \Lambda_2 in both cases (i) and (ii), where I_0 is the intensity of the incident wave, L is the slab thickness, and \Lambda_2 is an intensity-dependent "SH scattering" length.Comment: PDF, 20 pages, 4 figure

Governor Baker's Public Schedule (2018-04-22)

<em>Over the past years, the role of physical education and sports in youth health improvement has deteriorated, the public status of physical training for purposes of health improvement and promotion has fallen. The article outlines the results of a study of attitudes to physical education and sports among 310 senior grades in secondary schools of the town of Zhukovsky in Moscow region under the program of research into health-saving behaviours in adolescents. Along with a low sports activity most adolescents of both sexes do not do morning exercises at all. At the same time, their overall motor performance is also at a very low level. The sedentary life style becomes a dominant feature in the development of younger generation.</em><br /><strong><em>Key words: adolescents, attitude to sports, motor performance.</em></strong

THEORETIC APPROACHES TO THE WORKING OUT PROGRAM (QUESTIONNAIRE) OF HEALTH-SAVING BEHAVIOR STUDY IN ADOLESCENTS OF 15–17 YEARS OLD

The article reflects basic stages of development of questionnaire studying peculiarities of health-saving behavior of adolescents of 15–17 years old, and factors influencing on it. Necessary condition to the questionnaires’ working out is to keep in mind the specific changes, taking place in this age. The results of questionnaire may be useful in distribution of adolescents into groups depending on criteria of psychological compatibility, primary behavioral risk factors, attitude, etc. It creates conditions for the optimization of work in the field of stable health-saving behavior.Key words: adolescents, health-saving, questionnaire.(Voprosy sovremennoi pediatrii — Current Pediatrics. 2009;8(4):23-25

Bistability and explosive transients in surface reactions: the role of fluctuations and spatial correlations

We study the dynamics of a class of catalytic surface reactions in which an adsorbed molecule undergoes dissociation giving oxygen, which then rapidly reacts with H adatoms to give water. The reaction-diffusion equations predict bistability and explosive transients similar to those observed in several low-pressure experiments. Kinetic Monte Carlo simulations reveal however that the dynamics can be strongly affected by spontaneous, inhomogeneous fluctuations of composition on the surface. In particular, bifurcation points can be displaced and the explosive character of the transients can be lost, depending on a subtle balance between the rate of reaction and the mobility of the decomposing species. These effects can be quantified on the basis of a stochastic formulation of the dynamics taking into account spatial correlations. This approach allows to better delimit the applicability of the traditional reaction-diffusion modelling in the case of reactions such as the reduction of NO x or SO x species on catalytic surfaces. © 2010 EDP Sciences, Società Italiana di Fisica, Springer-Verlag.SCOPUS: ar.jinfo:eu-repo/semantics/publishe