On the radiative lifetime of free-moving two-dimensional excitons

A simple microscopic mechanism explaining the linear dependence of the radiative lifetime of free-moving two-dimensional excitons on their effective temperature is suggested. It is shown that there exists a characteristic effective temperature (of about few Kelvin) defined by the exciton-acoustic phonon interaction at which the radiative lifetime is minimal. Below this temperature the lifetime starts to increase with decreasing temperature. The correspondence with previous theoretical and experimental results is discussed.Comment: 5 pages, 3 figures. Final versio

Asymptotic properties of Lp-estimators

Some sufficient conditions for consistency and asymptotic normality of a non-linear regression parameter Lp-estimator are presented for a continuous time regression model with Gaussian stationary noise possessing the long-range dependence or weak dependence property

Суспільно-політична та культурно-просвітницька діяльність наукових осередків української діаспори в США

Досліджується та аналізується питання діяльності українських наукових осередків на території США. Особливу увагу приділено головним центрам науки української діаспори, а саме: Науковому товариству ім. Т. Шевченка, Українській вільній академії наук та Українському інституту Америки.The activity of Ukrainian scientific center on the area of U.S.A. is explorer and analyzed. The special attention is considered on three main centre of science of Ukrainian. Diaspora, and exactly on Scientific Society of name T. Shevchenko, Ukrainian free academy of science and Ukrainian institute of America

Conformal properties of hypermultiplet actions in six dimensions

We consider scale-invariant interactions of 6D N=1 hypermultiplets with the gauge multiplet. If the canonical dimension of the matter scalar field is assumed to be 1, scale-invariant lagrangians involve higher derivatives in the action. Though scale-invariant, all such lagrangians are not invariant with respect to special conformal transformations and their superpartners. If the scalar canonical dimension is assumed to be 2, conformal invariance holds at the classical, but not at the quantum level.Comment: 14 pages, 1 figur

Роль очагов инфекции при различных кожных заболеваниях

Reviewed scientific publications that define the location of foci of chronic infections in dermatology. Indicated by the currently existing problematic issues and their solutions.Проанализированы научные публикации, определяющие место очагов хронической инфекции в дерматологии. Обозначены существующие на данный момент проблемные вопросы и пути их решения

Nonlocal field correlators on the lattice in HP^1 sigma-model

Connected two-point field strength correlators have been measured on the lattice in quaternionic projective sigma-model of pure SU(2) Yang-Mills theory. The correlation lengths, extracted from the exponential fit for these correlators, are found to be lambda_1^{-1} = 1.40(3) GeV and lambda^{-1} = 1.51(3) GeV in good agreement with other existing calculations. The dependence of bilocal functions on the connector shape was studied.Comment: 11 pages, 9 figures, to be published in JETP Letter

Chiral anomalies in higher-derivative supersymmetric 6D gauge theories

We show that the recently constructed higher-derivative 6D SYM theory involves an internal chiral anomaly breaking gauge invariance. The anomaly is cancelled when adding to the theory an adjoint matter hypermultiplet.Comment: A missed contribution added. The article is rather essentially reshuffle

Parameter estimators of nonlinear quantile regression

We have obtained the asymptotic normality of parameter estimators of a nonlinear quantile regression with nonsymmetric random noise