Looking at a soliton through the prism of optical supercontinuum

A traditional view on solitons in optical fibers as robust particle-like structures suited for informa- tion transmission has been significantly altered and broadened over the past decade, when solitons have been found to play the major role in generation of octave broad supercontinuum spectra in photonic-crystal and other types of optical fibers. This remarkable spectral broadening is achieved through complex processes of dispersive radiation being scattered from, emitted and transformed by solitons. Thus solitons have emerged as the major players in nonlinear frequency conversion in optical fibers. Unexpected analogies of these processes have been found with dynamics of ultracold atoms and ocean waves. This colloquium focuses on recent understanding and new insights into physics of soliton-radiation interaction and supercontinuum generation.Comment: http://rmp.aps.org/abstract/RMP/v82/i2/p1287_1 (some figures have been deleted due to space limits imposed by archive

Completely integrable models of non-linear optics

The models of the non-linear optics in which solitons were appeared are considered. These models are of paramount importance in studies of non-linear wave phenomena. The classical examples of phenomena of this kind are the self-focusing, self-induced transparency, and parametric interaction of three waves. At the present time there are a number of the theories based on completely integrable systems of equations, which are both generations of the original known models and new ones. The modified Korteweg-de Vries equation, the non- linear Schrodinger equation, the derivative non-linear Schrodinger equation, Sine-Gordon equation, the reduced Maxwell-Bloch equation, Hirota equation, the principal chiral field equations, and the equations of massive Thirring model are gradually putting together a list of soliton equations, which are usually to be found in non-linear optics theory.Comment: Latex, 17 pages, no figures, submitted to Pramana

Nonlinear surface waves in left-handed materials

We study both linear and nonlinear surface waves localized at the interface separating a left-handed medium (i.e. the medium with both negative dielectric permittivity and negative magnetic permeability) and a conventional (or right-handed) dielectric medium. We demonstrate that the interface can support both TE- and TM-polarized surface waves - surface polaritons, and we study their properties. We describe the intensity-dependent properties of nonlinear surface waves in three different cases, i.e. when both the LH and RH media are nonlinear and when either of the media is nonlinear. In the case when both media are nonlinear, we find two types of nonlinear surface waves, one with the maximum amplitude at the interface, and the other one with two humps. In the case when one medium is nonlinear, only one type of surface wave exists, which has the maximum electric field at the interface, unlike waves in right-handed materials where the surface-wave maximum is usually shifted into a self-focussing nonlinear medium. We discus the possibility of tuning the wave group velocity in both the linear and nonlinear cases, and show that group-velocity dispersion, which leads to pulse broadening, can be balanced by the nonlinearity of the media, so resulting in soliton propagation.Comment: 9 pages, 10 figure

МОДЕЛИРОВАНИЕ КАК МЕТОД НАУЧНОГО ПОЗНАНИЯ СЛОЖНЫХ МЯСНЫХ СИСТЕМ

The paper examines the issues associated with the integration of knowledge in meat product technology + computers + mathematical methods. The possibilities to use a computer system and mathematical methods for an optimal solution to tasks in the field of food biotechnology and meat product technology are demonstrated.The applied software program SSS Bio realized in the computer system was developed and described. Using the one-way analysis of variance, which is one of the system modules, a comprehensive amount of statistical data for interpretation of the results was obtained. The program modules (correlation and regression analysis) allow establishing the model structure and parameters that link quantitative resulting and factorial variables, as well as assessing a degree of their correspondence with the experimental data. This kind of statistical analysis makes it possible to solve the main task of an experiment when the observed and resulting variables are quantitative.Based on the experimental data obtained with the use of the computer system SSS Bio, the mathematical models of moisture binding capacity (MBC), moisture holding capacity (MHC) and fat binding capacity (FBC) in sausage meat were calculated for sausages with isolated soya protein depending on the fat and protein content using the module of multiple regression of the computer system.The obtained stochastic dependence of changes in MBC (Y) on the total protein (X1) and fat (X2) content in sausage meat shows that at the constant level of fat, an increase in total protein favors a growth in MBC of sausage meat. However, a growth in MBC per unit of protein decreases with an increase in the fat amount.В статье рассмотрены вопросы, связанные с  интеграцией знаний «технология мясных продуктов + компьютеры + математические методы». Показаны возможности использования компьютерной системы и математических методов для оптимального решения задач в  области пищевой биотехнологии и технологии мясных продуктов.Разработана и описана прикладная программа SSS Bio, реализованная в  компьютерной системе. При помощи однофакторного дисперсионного анализа, являющегося одним из модулей системы, получены исчерпывающее количество статистических данных для интерпретации результатов. Модули программы (корреляционный и  регрессионный анализ) позволяют установить структуру и  параметры модели, связывающей количественные результирующую и факторные переменные, и оценить степень ее согласованности с экспериментальными данными. Этот вид статистического анализа позволяет решать главную задачу эксперимента в  случае, если наблюдаемые и  результирующие переменные являются количественными.На основе экспериментальных данных при помощи компьютерной системы SSS Bio рассчитаны математические модели влагосвязывающей (ВСС), влагоудерживающей (ВУС) и жиросвязывающей (ЖСС) способностей в фарше для колбасных изделий с использованием соевого изолированного белка в зависимости от содержания жира и белка с использованием модуля множественной регрессии компьютерной системы.Полученная стохастическая зависимость изменения ВСС (Y) от содержания общего белка (X1) и жира (X2) в колбасном фарше показывает, что при постоянном уровне жира увеличение общего содержания белка способствует росту ВСС фарша. Однако рост ВСС на единицу белка уменьшается с увеличением количества жира

Pharmacodynamics of the Glutamate Receptor Antagonists in the Rat Barrel Cortex

Epipial application is one of the approaches for drug delivery into the cortex. However, passive diffusion of epipially applied drugs through the cortical depth may be slow, and different drug concentrations may be achieved at different rates across the cortical depth. Here, we explored the pharmacodynamics of the inhibitory effects of epipially applied ionotropic glutamate receptor antagonists CNQX and dAPV on sensory-evoked and spontaneous activity across layers of the cortical barrel column in urethane-anesthetized rats. The inhibitory effects of CNQX and dAPV were observed at concentrations that were an order higher than in slices in vitro, and they slowly developed from the cortical surface to depth after epipial application. The level of the inhibitory effects also followed the surface-to-depth gradient, with full inhibition of sensory evoked potentials (SEPs) in the supragranular layers and L4 and only partial inhibition in L5 and L6. During epipial CNQX and dAPV application, spontaneous activity and the late component of multiple unit activity (MUA) during sensory-evoked responses were suppressed faster than the short-latency MUA component. Despite complete suppression of SEPs in L4, sensory-evoked short-latency multiunit responses in L4 persisted, and they were suppressed by further addition of lidocaine suggesting that spikes in thalamocortical axons contribute ∼20% to early multiunit responses. Epipial CNQX and dAPV also completely suppressed sensory-evoked very fast (∼500 Hz) oscillations and spontaneous slow wave activity in L2/3 and L4. However, delta oscillations persisted in L5/6. Thus, CNQX and dAPV exert inhibitory actions on cortical activity during epipial application at much higher concentrations than in vitro, and the pharmacodynamics of their inhibitory effects is characterized by the surface-to-depth gradients in the rate of development and the level of inhibition of sensory-evoked and spontaneous cortical activity

Phylogenetic analysis of variants of the Puumala virus (Hantaviridae: <i>Orthohantavirus</i>) circulating in the Saratov region

The objective is to determine the complete nucleotide sequence and conduct a phylogenetic analysis of genome variants of the Puumala virus isolated in the Saratov region. Materials and methods. The samples for the study were field material collected in the Gagarinsky (formerly Saratovsky), Engelssky, Novoburassky and Khvalynsky districts of the Saratov region in the period from 2019 to 2022. To specifically enrich the Puumala virus genome in the samples, were used PCR and developed a specific primer panel. Next, the resulting PCR products were sequenced and the fragments were assembled into one sequence for each segment of the virus genome. To construct phylogenetic trees, the maximum parsimony algorithm was used. Results. Genetic variants of the Puumala virus isolated in the Saratov region have a high degree of genome similarity to each other, which indicates their unity of origin. According to phylogenetic analysis, they all form a separate branch in the cluster formed by hantaviruses from other subjects of the Volga Federal District. The virus variants from the Republics of Udmurtia and Tatarstan, as well as from the Samara and Ulyanovsk regions, are closest to the samples from the Saratov region. Conclusion. The data obtained show the presence of a pronounced territorial confinement of strains to certain regions or areas that are the natural biotopes of their carriers. This makes it possible to fairly accurately determine the territory of possible infection of patients and/or the circulation of carriers of these virus variants based on the sequence of individual segments of their genome

Estimation of signal delay when the parameters of the modulating interference are unknown

The variances of the quasi-optimal estimate and of the maximum-likelihood estimate of the signal delay for reception on a background of white noise are obtained