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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.

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.

Kudryk Ya.Ya.,Institute of Semiconductor Physics of Ukraine | Tkachenko A.K.,Zhytomyr State University | Zinovchuk A.V.,Zhytomyr State University
Semiconductor Science and Technology | Year: 2012

Temperature-dependent internal quantum efficiency (IQE) of multiple quantum well InGaN/GaN light-emitting diodes (LEDs) has been investigated. IQE versus current relation is analysed using the modified rate equation model that takes into account the current crowding effect at different temperatures. The results of calculations are consistent with the fact that droop in IQE at higher currents originates from Auger recombination increased by current crowding. It is shown that unusual experimentally observed temperature dependence of the efficiency droop can be explained by stronger lateral nonuniformity of carrier injection at low temperatures without any assumptions about carrier delocalization from In-rich regions in quantum wells. © 2012 IOP Publishing Ltd.

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

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.

Palkovskii Y.,Zhytomyr State University | Belov A.,Zhytomyr State University
CEUR Workshop Proceedings | Year: 2014

This paper describes approaches used for the Plagiarism Detection task during PAN 2014 International Competition on Uncovering Plagiarism, Authorship, and Social Software Misuse, that scored 1-st place with plagdet score (0.907) for test corpus no.3 and 3-rd place score (0.868) for test corpus no. 2. In this work we aggregated all the previously researched experience from PAN12 and PAN 13 research works [2] and thus further improved previously developed methods of detecting plagiarism [8], with the help of: contextual n-grams, surrounding context n-grams, named entity based n-grams, odd-even skip n-grams, functional words frame based n-grams, TF-IDF sentence level similarity index and noise sensitive clusterization algorithm, focused summary type detection heuristics, combined into a single model to mark similarity sections and thus effectively detect different types of obfuscation techniques.

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.

Zinovchuk A.V.,Zhytomyr State University
Technical Physics Letters | Year: 2014

The process of Auger recombination in n-type nitride compounds InxGa1 − xN at T = 300 K has been numerically simulated. The recombination rate was calculated proceeding from the energy-band structure and wave functions determined using the empirical pseudopotential method. An indirect Auger process with the participation of phonons was analyzed using the second-order perturbation theory and the method of spectral-density functions. It is established that, for compounds emitting light in the visible spectral range, the Auger coefficient can vary from 3.1 × 10−30 to 2.0 × 10−32 cm6/s and indirect recombination plays a secondary role. © 2014, Pleiades Publishing, Ltd.

Pogorui A.A.,Zhytomyr State University | Rodriguez-Dagnino R.M.,Monterrey Institute of Technology
Journal of Statistical Physics | Year: 2011

We study uniformly distributed direction of motion at finite speed where the direction alternations occur according to the renewal epochs of a K-Erlang pdf. At first sight, our generalizations of previous Markovian results appears to be a small step, however, it must be seen as an important non-Markovian case where we have found closed-form expressions for the pdf and the conditional characteristic function of this semi-Markov transport process. We present detailed calculations of a three-dimensional example for the 2-Erlang case, which is important not only from physical applications point of view but also to understand more general models. For instance, in principle the example of the 2-Erlang case can be extended to a K-Erlang case (K=3,4,...) but some of the mathematical expressions may be cumbersome. © 2011 Springer Science+Business Media, LLC.

The influence of crystal-lattice oscillations on the spectrum of electron occurring in a cascade of several-nanometer-thick planar layers has been studied. It is shown which phonons affect the emission spectrum of a heterolaser based on this structure, depending on the layer thickness. © 2014 Pleiades Publishing, Ltd.

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