Asymptotic analysis of MMPP/M/1 retrial queueing system with unreliable server

In this paper, we study a single-server retrial queueing system with arrival Markov Modulated Poisson Process and an exponential law of the service time on an unreliable server. If the server is idle, an arrival customer occupies it for the servicing. When the server is busy, a customer goes into the orbit and waits a random time distributed exponentially. It is assumed that the server is unreliable, so it may fail. The server’s repairing and working times are exponentially distributed. The method of asymptotic analysis is proposed to find the stationary distribution of the number of customers in the orbit. It is shown that the asymptotic probability distribution under the condition of a long delay has the Gaussian form with obtained parameters

Stem-technologies: mathematics and informatics

Algorithms solutions of tasks in the field of the theory of numbers within implementation of the STEM project are proposed and realized. Calculations in a package of computer algebra on an open code in the environment of Linux DebianПредложены и реализованы алгоритмы решения задач в области теории чисел в рамках реализации проекта STEM. Вычисления в пакете компьютерной алгебры на открытом коде в среде Linux Debia

Experimental (computing) theory of numbers

Carrying out numerical experiments with Euler's function. Specification of the theorem of Mertens. Calculations in a package of computer algebra on an open code in the environment of Linux DebianПроведение численных экспериментов с функцией Эйлера. Уточнение теоремы Мертенса. Вычисления в пакете компьютерной алгебры на открытом коде в среде Linux Debia

Plagiarism and “self-plagiarism” in scientific works in the age of digital technologies

As well as streamlining academic research activities, contemporary technologies provide opportunities to infringe on the intellectual property of others through plagiarism. However, plagiarism has yet to be adequately dealt with in national legislations, which either do not contain any provision in this connection or fail to adequately define the relevant terms. Moreover, there continues to be much discussion as to what plagiarism is, as well as how and in what cases it should be punishable. The situation is further complicated by the various approaches to plagiarism and the lack of consensus on whether so-called “self-plagiarism” should be treated separately from the intentional infringement of other people’s intellectual property or be deemed as a form of plagiarism. With the aim of clarifying these questions, the authors of the present paper compare different approaches taken to the problem of plagiarism and consider some contemporary approaches to plagiarism detection

Engineering robust cellulases for tailored lignocellulosic degradation cocktails

Lignocellulosic biomass is a most promising feedstock in the production of second-generation biofuels. Efficient degradation of lignocellulosic biomass requires a synergistic action of several cellulases and hemicellulases. Cellulases depolymerize cellulose, the main polymer of the lignocellulosic biomass, to its building blocks. The production of cellulase cocktails has been widely explored, however, there are still some main challenges that enzymes need to overcome in order to develop a sustainable production of bioethanol. The main challenges include low activity, product inhibition, and the need to perform fine-tuning of a cellulase cocktail for each type of biomass. Protein engineering and directed evolution are powerful technologies to improve enzyme properties such as increased activity, decreased product inhibition, increased thermal stability, improved performance in non-conventional media, and pH stability, which will lead to a production of more efficient cocktails. In this review, we focus on recent advances in cellulase cocktail production, its current challenges, protein engineering as an efficient strategy to engineer cellulases, and our view on future prospects in the generation of tailored cellulases for biofuel production. © 2020 by the authors. Licensee MDPI, Basel, Switzerland

Simple method for sub-diffraction resolution imaging of cellular structures on standard confocal microscopes by three-photon absorption of quantum dots

This study describes a simple technique that improves a recently developed 3D sub-diffraction imaging method based on three-photon absorption of commercially available quantum dots. The method combines imaging of biological samples via tri-exciton generation in quantum dots with deconvolution and spectral multiplexing, resulting in a novel approach for multi-color imaging of even thick biological samples at a 1.4 to 1.9-fold better spatial resolution. This approach is realized on a conventional confocal microscope equipped with standard continuous-wave lasers. We demonstrate the potential of multi-color tri-exciton imaging of quantum dots combined with deconvolution on viral vesicles in lentivirally transduced cells as well as intermediate filaments in three-dimensional clusters of mouse-derived neural stem cells (neurospheres) and dense microtubuli arrays in myotubes formed by stacks of differentiated C2C12 myoblasts

Cellulases from Mycelial fungi <em>Penicillium verruculosum</em> as a Real Alternative to Trichoderma Enzymes in Industrial Hydrolysis of Cellulosic Biomass

Abstract The possibility of using the recipient strain Penicillium verruculosum B1-537 (ΔniaD) as a producer of laboratory and industrial enzymes was considered. The advantage of this strain is its ability to secrete a basic cellulase complex consisting of cellobiohydrolases, endoglucanases, and β-glucosidase, which exceeds in its hydrolytic ability the enzyme complex of Hypocrea (Trichoderma) strains. Using the expression system, the basic complex of cellulases of the recipient strain Piptochaetium verruculosum B1-537 (ΔniaD) was supplemented with new (booster) enzymes that are necessary to increase its hydrolytic activity. Enzyme preparations adapted to the processing of various types of renewable plant biomass were obtained