Stability of constant retrial rate systems with NBU input*

We study the stability of a single-server retrial queueing system with constant retrial rate, general input and service processes. First, we present a review of some relevant recent results related to the stability criteria of similar systems. Sufficient stability conditions were obtained by Avrachenkov and Morozov (2014), which hold for a rather general retrial system. However, only in the case of Poisson input is an explicit expression provided; otherwise one has to rely on simulation. On the other hand, the stability criteria derived by Lillo (1996) can be easily computed but only hold for the case of exponential service times. We present new sufficient stability conditions, which are less tight than the ones obtained by Avrachenkov and Morozov (2010), but have an analytical expression under rather general assumptions. A key assumption is that interarrival times belongs to the class of new better than used (NBU) distributions. We illustrate the accuracy of the condition based on this assumption (in comparison with known conditions when possible) for a number of non-exponential distributions

Poetical understanding of posttraumatic syndrome

В статье рассматривается пример заимствования контркультурных понятий, их трансформации и «возвращения» через произведения актуального искусства. Автором исследуются особенности перевода песенных текстов и их адаптация к традициям иноязычной аудитории.The article is focused on an example of countercultural concepts borrowing, transformation and recurrence of these concepts through the contemporary artworks. The authors analyze distinctive features of song texts translation and adaptation of them to traditions of an audience speaking another language

Melatonin in Th17/Treg differentiation: the contribution of the hormone's own production by T lymphocytes

The hormone melatonin is involved in regulation of functioning of almost all organs and systems of the organism. In the immune system, T lymphocytes are an important target of melatonin: they express specific melatonin receptors with different affinities – membrane MT1 and MT2 and nuclear RORa, as well as intracellular molecules that nonspecifically bind melatonin at high concentrations. Moreover, many in vitro studies reveal their own production of melatonin by T lymphocytes in response to polyclonal activation and its involvement as autocrine or paracrine factor in the induction of IL-2 and IL-2 receptor (IL-2R) synthesis by T cells, with melatonin receptors involvement in implementation of these effects. Since IL-2/IL-2R-dependent signal is a key event in T lymphocytes proliferative response induction, intrinsic melatonin seems to be directly involved at least in the clonal expansion of these cells. In this work, we investigated the contribution of T cells’ melatonin to regulation of the next stage of T lymphocyte activation, namely, the differentiation of T helper populations Th17 and Treg. It was shown that blockade of both membrane and nuclear melatonin receptors did not cause statistically significant changes in Th17 differentiation, although the trend was fixed for a decrease. Simultaneously, CD4+FoxP3+Т cells level decreased under the nonselective blockade of membrane hormone receptors, and Treg-associated cytokine TGF-b concentration in activated cultures supernatants decreased both in case of MT1/MT2 nonselective blockade and MT2 selective blockade. The data indicate that melatonin produced by T lymphocytes in culture can contribute to the control of naive CD4+T cell differentiation into Treg in vitro, and the hormone effects are mediated by membrane melatonin receptors. The presence of a large number targets with different affinities for melatonin in T lymphocytes determines the key role of the hormone concentration in its effects on these cells. And when interpreting data on melatonin-dependent regulation of Treg, it is important to take into account the hormone’s own production by lymphocytes, since T cells’ melatonin can mask the exogenous hormone effects or interfere with its action due to competitive binding to hormone receptors

Developing a modern thermal strengthening technique for regulated fishplate cooling

A modern ecologically friendly technique for fishplate (joint bar) thermal strengthening by regulated water cooling is proposed. The proposed technique can successfully replace the conventional one - oil quenching - due to making the cooling process more controlled by obtaining a uniform temperature distribution over fishplate elements with a different mass such as heads and the wet. The oil quenching process is an out of control fire hazardous one and requires controlling the permanent cooling capability, fishplate flushing after the operation. It is necessary to utilize the oil and to have a special ventilation system. As a mineral oil substitute, the usage of polymer media has been investigated. Within the time, the polymer solution needs to be recycled; the high cost of polymer concentrates also plays an important role. Quenching by water spraying is the most ecological and controlled type of thermal strengthening. The technique was validated by a test bench experiment and implemented in the metallurgical industry. The mechanical properties have been obtained to meet the GOST 4133-73 technical requirements. Moreover, the analysis made showed that when the controlled cooling device is fitted into the line existing due to exclusion of the hardening tank and washing machine from the processing flow it is possible to save energy, exclude the expenditures for acquisition, the preparation of oil and washing mixtures as well as for regeneration of the oils used and washing solutions. © 2014 WIT Press.International Journal of Safety and Security Engineering;International Journal of Sustainable Development and Planning;WIT Transactions on Ecology and the Environmen

Cryptic Diversity in Paramecium multimicronucleatum Revealed with a Polyphasic Approach

Paramecium (Ciliophora) systematics is well studied, and about twenty morphological species have been described. The morphological species may include several genetic species. How-ever, molecular phylogenetic analyses revealed that the species diversity within Paramecium could be even higher and has raised a problem of cryptic species whose statuses remain uncertain. In the present study, we provide the morphological and molecular characterization of two novel Paramecium species. While Paramecium lynni n. sp., although morphologically similar to P. multimicronucleatum, is phylogenetically well separated from all other Paramecium species, Paramecium fokini n. sp. appears to be a cryptic sister species to P. multimicronucleatum. The latter two species can be distinguished only by molecular methods. The number and structure of micronuclei, traditionally utilized to discriminate species in Paramecium, vary not only between but also within each of the three studied species and, thus, cannot be considered a reliable feature for species identification. The geographic distribution of the P. multimicronucleatum and P. fokini n. sp. strains do not show defined patterns, still leaving space for a role of the geographic factor in initial speciation in Paramecium. Future findings of new Paramecium species can be predicted from the molecular data, while morphological characteristics appear to be unstable and overlapping at least in some species

Применение гуселькумаба при псориатическом артрите: данные реальной клинической практики

Psoriatic arthritis (PsA) is a chronic inflammatory disease of the joints, spine and enthesis from the group of spondyloarthritis that develops in patients with psoriasis. Guselkumab is a biologic disease-modifying antirheumatic drug, an inhibitor of interleukin 23, which has been shown to be effective in the treatment of plaque psoriasis and PsA.Objective: to evaluate the effectiveness of guselkumab treatment in PsA patients.Patients and methods. The study included 16 patients with PsA. All patients received 100 mg of guselkumab subcutaneously at weeks 0, 4, 12, 20. Disease activity and treatment efficacy were assessed at weeks 0, 12 and 24 using the DAS28, ASDAS, BASDAI, DAPSA activity indices, the index of the extent and severity of psoriasis PASI.Results and discussion. During treatment, patients with PsA showed a pronounced positive dynamics of the indices of disease activity and an improvement in the skin condition. Before the treatment with guselkumab, the mean value of the DAS28 index was 4.26±0.64, DAPSA – 37.94±9.45, ASDAS – 2.7±0.65, and BASDAI – 5.49±1.39, after 12 weeks of treatment these indicators decreased to 3.03±0.49; 17.06±4.58; 1.64±0.33 and 3.48±0.66, respectively, and after 24 weeks (after the 4th injection) – to 2.32±0.18; 11.31±2.18; 1.22±0.27 and 2.62±0.78, respectively (p<0.05 for all cases). Before treatment, the average PASI index reached 30.99±15.43, after 12 weeks – 4.55±4.82, and after 24 weeks – 1.05±1.46 (p<0.05). During treatment, a significant improvement in the main manifestations of the disease was noted: regression of peripheral arthritis, spondylitis, and skin rashes.The treatment was well tolerated during the 24 weeks of the study, and no serious adverse events were reported.Conclusion. The data from real clinical practice indicate that guselkumab is highly effective and safe in the treatment of PsA.Псориатический артрит (ПсА) – хроническое воспалительное заболевание суставов, позвоночника и энтезисов из группы спондилоартритов, развивающееся у больных псориазом. Гуселькумаб – генно-инженерный биологический препарат, ингибитор интерлейкина 23, показавший эффективность в терапии бляшечного псориаза и ПсА.Цель исследования – оценка эффективности лечения гуселькумабом больных ПсА.Пациенты и методы. В исследование включено 16 пациентов с ПсА. Все пациенты получали гуселькумаб в дозе 100 мг подкожно на неделях 0, 4, 12, 20. Оценка активности заболевания и эффективности лечения осуществлялась на неделях 0, 12 и 24 с применением индексов активности DAS28, ASDAS, BASDAI, DAPSA, индекса распространенности и тяжести псориаза – PASI.Результаты и обсуждение. В ходе лечения у больных ПсА наблюдались выраженная положительная динамика индексов активности заболевания и улучшение состояния кожи. Если до начала лечения гуселькумабом среднее значение индекса DAS28 составляло 4,26±0,64, DAPSA – 37,94±9,45, ASDAS – 2,7±0,65 и BASDAI – 5,49±1,39, то через 12 нед произошло снижение этих показателей до 3,03±0,49; 17,06±4,58; 1,64±0,33 и 3,48±0,66 соответственно, а через 24 нед (после 4-й инъекций) – уже до 2,32±0,18; 11,31±2,18; 1,22±0,27 и 2,62±0,78 соответственно (p<0,05 для всех случаев). До начала лечения среднее значение индекса PASI достигало 30,99±15,43, через 12 нед – 4,55±4,82 и через 24 нед – 1,05±1,46 (p<0,05). На фоне лечения отмечено значительное улучшение основных проявлений заболевания: регресс периферического артрита, спондилита и кожных высыпаний.На протяжении 24 нед исследования переносимость терапии была хорошей, серьезных нежелательных явлений не зарегистрировано.Заключение. Данные, полученные в условиях реальной клинической практики, свидетельствуют о высокой эффективности и безопасности гуселькумаба при лечении ПсА

On the Issue of Universal Practical Skills of Teachers of Secondary Vocational Education

В условиях массовой цифровизации и четвертой промышленной революции перед системой среднего профессионального образования (СПО) в Российской Федерации стоят задачи по подготовке специалистов, готовых к будущим изменениям в профессиональной сфере. В статье рассматриваются универсальные навыки, необходимые педагогам СПО для создания эффективного образовательного процесса при подготовке специалистов рабочих профессий. Авторы выделяют такие ключевые фигуры процесса обучения как педагог теоретического обучения и мастер производственного обучения и обосновывают необходимость профессионального взаимодействия между специалистами.In the context of mass digitalization and the fourth industrial revolution, the system of secondary vocational education (SVE) in the Russian Federation is faced with the task of training specialists who are ready for future changes in the professional field. The article discusses the universal skills necessary for teachers of secondary vocational education to create an effective educational process in the preparation of blue-collar workers. The authors identify such key figures in the learning process as a teacher of theoretical training and a master of industrial training and substantiate the need for professional interaction between specialists

Patient with Jaundice, Dyspnea and Hyperferritinemia after COVID-19

The aim: to highlight the importance of considering hemophagocytic lymphohistiocytosis in patients with jaundice of unclear origin and systemic inflammatory manifestations after coronavirus infection.Key points. A 64-y.o. patient was admitted to the hospital with jaundice, pruritus, fatigue, weight loss. The complaints occurred 2 weeks after discharge from the hospital for treatment of patients with coronavirus infection. Laboratory tests revealed signs of hepatic insufficiency, markers of cholestasis and inflammation persisted in time. Upon instrumental examination no signs of hepatosplenomegaly, biliary tree changes, intra- and extrahepatic obstruction were found. S. aureus was identified in blood cultures, CT scan of the facial skull bones showcased the focus of infection in the area of the roots of teeth 2.4 and 2.5. Therefore, antibiotics were prescribed. Subsequently, the patient's condition was complicated by the development of two episodes of acute respiratory distress syndrome, which occurred during the withdrawal of glucocorticosteroid therapy. Liver biopsy was performed, morphological study revealed signs of “vanishing bile duct” syndrome, excessive activation of macrophages and hemosiderosis of sinusoidal cells. Identified lesions can be found in hemophagocytic lymphohistiocytosis (HLH), a life-threatening complication of coronavirus infection. Glucocorticosteroids therapy, transfusions of human immunoglobulin, albumin, and parenteral nutrition have led to patient's condition improvement.Conclusion. COVID-19 provokes the development of secondary HLH 10 times more often than other respiratory viral infections. The possibility of hemophagocytic syndrome development should be considered, including cases of overlap syndrome with sepsis, in patients with unresolved jaundice, hyperferritinemia after coronavirus infection. Routinely used scales and criteria for diagnosis of HLH (H-score, HLH 2004) in such cases lacks sensitivity, therefore, careful analysis of clinical picture and exclusion of other causes of jaundice are required

Dibenzo[ f,h]furazano[3,4- b]quinoxalines: Synthesis by Intramolecular Cyclization through Direct Transition Metal-Free C-H Functionalization and Electrochemical, Photophysical, and Charge Mobility Characterization

Herein, we describe the synthesis of unsymmetrically substituted dibenzo[f,h]furazano[3,4-b]quinoxalines by intramolecular cyclization through direct transition metal-free C-H functionalization. The electrochemical and photophysical properties for several polycycles have been measured. In thin films of the dibenzo[f,h]furazano[3,4-b]quinoxalines, hole mobility is in the order of 10-4 cm2 V-1 s-1. The results show that the HOMO and LUMO energy levels are appropriate for using the compounds as hole-transport materials in thin-film devices, in particular, organic and perovskite solar cells. Copyright © 2020 American Chemical Society.Russian Foundation for Basic Research, RFBR: 18-33-00103-mol_aRussian Science Foundation, RSF: 18-13-00409The research was financially supported by the Russian Science Foundation (project no. 18-13-00409). Y.A.K would like to acknowledge the financial support for the part of the synthetic section from the Russian Foundation for Basic Research (research project no. 18-33-00103-mol_a). The authors are grateful to Grigory A. Kim for carrying out the DFT calculations, which were performed by using “Uran” supercomputer of the Institute of Mathematics and Mechanics of the Ural Branch of the Russian Academy of Sciences. NMR experiments were carried out by using equipment of the Center for Joint Use “Spectroscopy and Analysis of Organic Compounds” at the Postovsky Institute of Organic Synthesis of the Ural Branch of the Russian Academy of Sciences