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  • Author: D. Kuznetsov x
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Sequences of the second internal transcribed spacer of ribosomal DNA for three species of Trichostrongylus (Nematoda: Trichostrongylidae) from sheep in Russia

Abstract

For the first time, DNA sequence data were obtained for three species of Trichostrongylus from Russia. Internal transcribed spacer (ITS-2) of ribosomal DNA was sequenced for T. axei, T. colubriformis and T. probolurus from sheep from the Moscow region. ITS-2 rDNA length was estimated as 238 nucleotides for T. colubriformis and T. probolurus and 237 nucleotides for T. axei. The G+C content of the ITS-2 sequences of T. colubriformis, T. axei and T. probolurus were 31 %, 32 % and 34 % respectively. The level of interspecific differences in ITS-2 of rDNA of T. axei, T. probolurus and T. colubriformis ranged from 3 to 4 %. The ITS-2 sequences from the Russian specimens were compared with those of T. axei, T. probolurus and T. colubriformis from Australia and Germany. Intraspecific variation ranged from 0 % in T. colubriformis to 3.0 % in T. axei.

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Models and Algorithms for Estimation and Minimization of the Risks Associated with Dredging

Abstract

There are a lot of models and algorithms to minimize risks during dredging operations and they are not without drawbacks. The paper describes the authors’ approach to solving this problem. Mathematical models are proposed and on their basis software is developed. Methods of the risk theory are used to minimize the risks. In this paper a consequence of influence refers to the deviation from the goal expressed in the expected results and the deviation of certain criterion factors. In this case, we mean any measure of quality. In its turn, risk factors reduce criterion factors. These factors are divided into categories - general transportation risks and risks of transporting ground. In these categories, one may derive the following risks - incidents at transport resulting from the impact of a set of random factors including the human one. For risk analysis and management, in addition to identifying critical chains of risk situations, the stochastic model for evaluating the chains is set forth. In order to implement this algorithm, the mathematical package Maple is used, which allows for conducting the required calculations with a software package including the Graph Theory. The paper presents fragments of the code listing.

Open access
On gastrointestinal nematodes of Mongolian gazelle (Procapra gutturosa)

Abstract

The species composition of nematodes found at autopsy of abomasa and small intestines of 24 Mongolian gazelles in Eastern Mongolia is studied. Orloffia bisonis, Marshallagia mongolica, Nematodirus archari, N. andreevi, Trichostrongylus colubriformis, T. probolurus were registered. N. archari and N. andreevi were detected in Mongolian gazelle for the first time. All species of gastrointestinal nematodes found in Mongolian gazelles have already been registered in domestic ruminants of Mongolia. The validity of Orloffia genus is confirmed based on our own observations and literature data. Orloffia is monotypic genus with the only species O. bisonis represented by two morphs where “O. bisonis” is major and “O. kasakhstanica” is minor.

Open access