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Zhytomyr, Ukraine

Modern methods for obtaining metaphase plates from the somatic cells of fish, most effective in the study of polyploid species, were selected and tested. The technique with CoCl2and colchicine treatment is recommended on the basis of empirical data for representatives of the genera Carassius and Cobitis. Th e detailed description of this modified technique and characteristics of metaphase plates of Carassius auratus Linnaeus, 1758, Carassius carassius Linnaeus, 1758 and triploid form of Cobitis taenia Linnaeus, 1758 received under tested method is presented in the paper. © by P. P. Pukhtayevych. Source

Propagation processes of indigenous mussels of water reservoirs and water currents of Ukraine proceed inadequately. In Anodonta anatina (Linnaeus, 1758), 100 % of female mussels reproduced in about 60 % of collection points, in the rest of collection points only 17-90 % of female mussels appeared to be pregnant, and in A. cygnea (Linnaeus, 1758) this number was about 50 %. In almost 70 % of collection points, A. cygnea and Pseudanodonta complanata Rossmassler, 1835 female mussels' marsupia were not completely filled with reproductive products. On the other hand, invasive Chinese mussel, Sinanodonta woodiana (Lea, 1834), had multiple ovipositions during the whole year, its hemibranchs were completely filled with reproductive products. © 2015 by L. M. Yanovych. Source

Zinovchuk A.V.,Zhytomyr State University
Optical and Quantum Electronics | Year: 2015

Direct and phonon-assisted mechanisms of Auger recombination in bulk (Formula presented.)-(Formula presented.) wurtzite alloys are numerically investigated. The matrix elements of electron–electron and electron–phonon interaction are calculated using the band structure and wave functions obtained by the empirical pseudopotential method. Phonon-assisted Auger process is analyzed by the spectral density functions approach. The dependences of Auger recombination coefficient on the energy band gap of (Formula presented.)-(Formula presented.) alloys, temperature and carrier concentration are presented. The calculated Auger coefficients for alloys corresponding to the visible spectrum exhibit strong reduction at high carrier concentration. © 2015 Springer Science+Business Media New York Source

Kudryk Y.Y.,Institute of Semiconductor Physics of Ukraine | Zinovchuk A.V.,Zhytomyr State University
Semiconductor Science and Technology | Year: 2011

We demonstrate that the efficiency droop phenomenon in multiple quantum well InGaN/GaN light-emitting diodes (LEDs) may be connected to the current crowding effect. A numerical model of internal quantum efficiency calculation is presented that takes into account nonuniform lateral carrier injection in the active region. Based on this model, we examine the effect of current crowding on the efficiency droop using comparison of simulated internal quantum efficiency of InGaN LEDs with low and high uniformity of current spreading. The results of simulations and measurements show that the devices with low uniformity of current spreading exhibit higher efficiency droop and lower roll-off current value. © 2011 IOP Publishing Ltd. Source

Pogorui A.A.,Zhytomyr State University | Rodriguez-Dagnino R.M.,Monterrey Institute of Technology
Journal of Statistical Physics | Year: 2012

In this paper we deal with uniformly distributed direction of motion or isotropic motion at random speed or velocity where the direction alternations occur according to the renewal epochs of a general distribution. We derive the renewal equation for the characteristic function of the transition density of the multidimensional motion. Then, by using the renewal equation, we study the behavior of the transition density near the sphere of its singularity for one-, two-, three-, and four-dimensional cases. To illustrate our solution methodology we present detailed calculations of many solvable examples. © 2012 Springer Science+Business Media, LLC. Source

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