Modeling of Isotropic Backward-Wave Materials Composed of Resonant Spheres

A possibility to realize isotropic artificial backward-wave materials is theoretically analyzed. An improved mixing rule for the effective permittivity of a composite material consisting of two sets of resonant dielectric spheres in a homogeneous background is presented. The equations are validated using the Mie theory and numerical simulations. The effect of a statistical distribution of sphere sizes on the increasing of losses in the operating frequency band is discussed and some examples are shown.Comment: 15 pages, 7 figure

Experiments on wave turbulence : the evolution and growth of second sound acoustic turbulence in superfluid 4He confirm self-similarity.

We report our experiments on the formation of second sound acoustic turbulence in superfluid 4He. The initial growth in spectral amplitude follows power laws that steepen rapidly with increasing harmonic number n, corresponding to a propagating front in frequency space. The lower growth exponents agree well with analytic predictions and numerical modeling. The observed increase in the formation delay with n validates the concept of selfsimilarity in the growth of wave turbulence

Parametric generation of second sound in superfluid helium: linear stability and nonlinear dynamics

We report the experimental studies of a parametric excitation of a second sound (SS) by a first sound (FS) in a superfluid helium in a resonance cavity. The results on several topics in this system are presented: (i) The linear properties of the instability, namely, the threshold, its temperature and geometrical dependencies, and the spectra of SS just above the onset were measured. They were found to be in a good quantitative agreement with the theory. (ii) It was shown that the mechanism of SS amplitude saturation is due to the nonlinear attenuation of SS via three wave interactions between the SS waves. Strong low frequency amplitude fluctuations of SS above the threshold were observed. The spectra of these fluctuations had a universal shape with exponentially decaying tails. Furthermore, the spectral width grew continuously with the FS amplitude. The role of three and four wave interactions are discussed with respect to the nonlinear SS behavior. The first evidence of Gaussian statistics of the wave amplitudes for the parametrically generated wave ensemble was obtained. (iii) The experiments on simultaneous pumping of the FS and independent SS waves revealed new effects. Below the instability threshold, the SS phase conjugation as a result of three-wave interactions between the FS and SS waves was observed. Above the threshold two new effects were found: a giant amplification of the SS wave intensity and strong resonance oscillations of the SS wave amplitude as a function of the FS amplitude. Qualitative explanations of these effects are suggested.Comment: 73 pages, 23 figures. to appear in Phys. Rev. B, July 1 st (2001

Ore-forming Сonditions of the Blagodat Gold Deposit in the Riphean Metamorphic Rocks of the Yenisey Ridge According to Geochemical and Isotopic Data

Neodymium and strontium isotopic composition and rare earth elements (REE) distribution pattern have been determined in whole rocks and minerals were separated from host metamorphic rocks and disseminated sulfide ores of the Blagodat gold deposit. Isotopic data are given to construct few isochrones that could be reflected an age of main stages of metamorphic and metasomatic alteration in rocks varieties during a successive accumulation of gold in structural traps. The significant temporal range in the forming of the studied rocks can be interpreted as an evidence of multi-stage tectonic destruction accompanying with trust-folding processes, shear deformations and development of local fracture zones that had place from the Late Riphean to Middle Paleozoic time. According to isotopic data basic ore-forming processes were realized in the relatively narrow interval from 690 to 750 Ma that correspond to a beginning of continental rifting on the western margin of Siberian craton. Chemistry and trace element distribution are closed for host and auriferous schists and mainly showed differences in the composition initial sedimentary units. The middle negative value εNd (from -14 to -16) and very high positive value εSr (from +570 to +725) are mostly corresponded to that of upper continental crust matter. The role of synchronic granite intrusions in the studied area can be only estimated due to a generation of thermal energy and crustal fluids

Methods of estimation of dissipative properties of steels at low temperatures

Use of the methodology of multifractal parameterization of structures, for conducting an estimate of habits of change in micromechanisms of shattering of steel at different temperatures of the testings, reflecting to dynamic loudspeaker of the latent dissipative processes. This method allows to present quantitatively not only an over-all configuration of structure for actual natural materials, but also inhomogeneity of allocation geometrical, physical, chemical, etc. characteristics, according to the nature of investigated structure that cannot be reached ordinary methods

Методология расчета и анализа интегральных оценок показателей поляризации денежных доходов населения

At present time there are two indicators which are mainly used for estimates of differentiation of incomes of the population -coefficient of funds and Gini index. Being informative to a certain extent they however have a number of drawbacks. The article examines methodology of calculation and analysis of differentiation of the money incomes of population (alongside with traditional indicators such as coefficient of funds and Gini index) on the basis of integral estimates of the polarization indices of money income of population. The author gives the methodology of the distribution parameters calculation according to reports of Federal State Statistics Service of Russian Federation for the log-normal distribution of population. Apart from the known indicators the article suggests using new ones for assessing the stratification of the population by the level of money income - indicators of income polarization. The average income in the distribution is taken for the polarization border. The author considers the number and incomes of population below and above the average. The specific values of income are calculated and compared with each other in each ofthese groups. The author provides definition, methods and examples of calculation for polarization indices. For the first time ever it was proved that for log-normal distribution of the population the share of incomes of the population with incomes below the average level exactly equals the share of population with incomes above the average level. The proof of this statement follows the validity of the converse - for log-normal distribution the share of incomes of the population with incomes above the average level exactly equals the share of population with incomes below the average level. The polarization index is determined by arithmetical operations with a single value of standard function which is - any share of population or money income with income below or above the average level. The author determines the trajectory of movement of this index in the coordinates «the shares of population - the shares of money income». Index of polarization differs from the Gini coefficient by clear economic interpretation, simplicity and accuracy of calculations. Moreover, the polarization index can be calculated taking into account the income of «disadvantaged» groups. It is shown that in addition to using the polarization index, one can use the reciprocal - the criterion of polarization.В настоящее время для оценок дифференциации денежных доходов населения используются в основном два показателя: коэффициент фондов и индекс Джини. Обладая определенной информативностью, они тем не менее не лишены недостатков. В статье описывается методология расчета и анализа дифференциации денежных доходов населения (наряду с традиционными показателями - коэффициентом фондов и индексом Джини) на основе интегральных оценок показателей поляризации денежных доходов населения. При гипотезе логарифмически нормального распределения населения методология расчета параметров модели распределения реализуется традиционно - по отчетным данным Росстата. Автор считает, что для измерения масштабов расслоения населения по уровню денежных доходов, наряду с известными показателями, целесообразно использовать показатели поляризации денежных доходов. В качестве границы поляризации принимается величина среднего дохода в распределении. Рассматриваются численность и доходы населения с доходами ниже и выше среднего уровня. В каждой из этих групп вычисляются удельные значения доходов и сравниваются между собой. В статье приведены определения показателей поляризации, методология и примеры их расчета. Впервые удалось показать, что для логарифмически нормального распределения доля доходов населения с доходами ниже среднего уровня в точности равна доле численности населения с доходами выше среднего уровня. Из доказательства этого утверждения следует справедливость обратного утверждения: для логарифмически нормального распределения доля доходов населения с доходами выше среднего уровня в точности равна доле численности населения с доходами ниже среднего уровня. Показатель - индекс поляризации - определяется арифметическими операциями с единственным значением стандартной функции - любой долей численности или доходов населения с доходами ниже или выше среднего уровня. Установлена траектория движения этого показателя в координатах: доли населения - доли доходов. Индекс поляризации отличается от индекса Джини ясностью экономической трактовки, простотой и точностью вычисления. Более того, индекс поляризации можно рассчитывать с учетом доходов «обездоленных» групп населения. Показано, что наряду с использованием индекса поляризации, имеет смысл рассчитывать обратную величину, интерпретируемую как критерий поляризации

Matter and physical anisotropy of ultramafites of the Barkhatny massif (Kuznetsk Alatau ridge, Western Siberia) as criteria of their mineral potential for geological prospecting works

A complex of petrographic, petrofabric, and paleomagnetic analyses that was carried out for rocks from an ultrabasic massif of the Barkhatnaya Mountain in the Northern part of the Kuznetsk Alatau allowed us to prove that internal anisotropy of mineral aggregates had deformation-type evolution, which indicates possible plastic exhumation of lithosphere mantle fragments into upper crust levels. Complete conformity of geophysical and petrofabric parameters points out high possibility of multistage model for obduction of ophiolite association segments proposed for this region. Taking into account specifics of minerageny for such complexes (chromite ores and noble metals, asbestos and nephrites), we offer a new technology for geological prospecting works at the stage of estimating mineral potential of such geological objects, which is based on the presence of differently oriented systems of mineral plane orientation.Проведенный нами комплекс структурно-петрологических и палеомагнитных исследований для ультрабазитов Бархатно- го массива на северном склоне Кузнецкого Алатау подтверждает, что внутренняя анизотропия минеральных агрегатов име- ла деформационную эволюцию, которая указывает на возможную пластическую эксгумацию фрагментов мантии литосферы в верхние горизонты земной коры. Полное соответствие геофизических и петроструктурных параметров отмечает высокую вероятность многостадийной обдукции фрагментов офиолитовой ассоциации, предлагаемой для этого региона. Принимая во внимание особенности минерагении (хромитовые руды и благородные металлы, асбест и нефрит) для таких комплексов мы предлагаем новые методы геологоразведочных работ на стадии оценки рудоносности геологических объектов, которые харак- теризуются дискретными вариациями пространственной ориентировки элементов текстурной анизотропии пород

Active Brownian Particles. From Individual to Collective Stochastic Dynamics

We review theoretical models of individual motility as well as collective dynamics and pattern formation of active particles. We focus on simple models of active dynamics with a particular emphasis on nonlinear and stochastic dynamics of such self-propelled entities in the framework of statistical mechanics. Examples of such active units in complex physico-chemical and biological systems are chemically powered nano-rods, localized patterns in reaction-diffusion system, motile cells or macroscopic animals. Based on the description of individual motion of point-like active particles by stochastic differential equations, we discuss different velocity-dependent friction functions, the impact of various types of fluctuations and calculate characteristic observables such as stationary velocity distributions or diffusion coefficients. Finally, we consider not only the free and confined individual active dynamics but also different types of interaction between active particles. The resulting collective dynamical behavior of large assemblies and aggregates of active units is discussed and an overview over some recent results on spatiotemporal pattern formation in such systems is given.Comment: 161 pages, Review, Eur Phys J Special-Topics, accepte