Search

The article considers multi-component and multi-stage mathematical models of queuing systems (QS) with the distribution of the incoming flow simultaneously between the system components, which consist of a certain number of service channels and waiting places in the queue. The maintenance of requirements with a lack of time to stay in the service channel and waiting is considered, while the service process in the QS of each component consists of several stages with the corresponding duration, and the full-service period is equal to the sum of such time intervals. The number of components and their parameters correspond to the similar characteristics of the production divisions of the repair enterprise. The study of the effectiveness of the operation of the repair enterprise as a multi-component and multi-stage QS consists in determining the values of the initial parameters of the QS components, taking into account the restrictions imposed on them, in order to obtain the largest values of the probabilities of servicing the requirements of the QS components and the system as a whole. The model is implemented using Any Logic University Researcher, which allows you to combine the principles of system dynamics with the paradigms of agent and discrete-event modelling. The proposed approach to the modelling of maintenance and repair processes by production divisions of the enterprise as a multi-component and multi-phase QS allows to determine the effectiveness of the functioning of such a QS and to obtain arguments for increasing the efficiency of its operation. [ABSTRACT FROM AUTHOR]

The purpose of the work is to build, on the basis of multi-component and multi-phase models of queuing systems (QS), mathematical models of maintenance and repair of vehicles by repair enterprises to increase the efficiency of their use. Results. The article considers multi-component and multi-stage mathematical models of QSs with the distribution of the arrival flow simultaneously between the system components, which consist of a certain number of service channels and waiting places in the queue. The same service channels can have different performance depending on the type of customers which they serve. Customers go through several stages of service and waiting. Considered are service of customers without a lack of time to stay in the service channel and waiting and with a lack of such time. The service process in the QS of each component consists of several (ke) stages with the corresponding duration, the full-service period will be equal to the sum of such time intervals. Stage durations have certain probability distributions with appropriate parameters, then the total duration of the service process will have a generalized Erlang distribution with parameters of probability distributions of stages of order ke. The number of components and their parameters correspond to the similar characteristics of the production divisions of the repair enterprise. The study of the effectiveness of the repair enterprise operation as a multi-component and multi-stage QS consists in determining the probability of service and the probability of failure of QS components and the system as a whole, the number of service channels, the number of customers in components, the number of customers in component queues, the duration of maintenance of customers in components and the system, the duration of being customers in queues of components and QSs, duration of stay of requirements in QSs and duration of customer waiting in QS queues. The model is implemented using Any Logic University Researcher. The AnyLogic University Researcher development environment allowed to combine the principles of system dynamics with the paradigms of agent and discrete-event modeling. In addition, thanks to the built-in Java SE compiler, a library of ready-made solutions is available, including generators of random variables, which significantly expands the possibilities of developing and implementing experiments. In particular, experiments on optimization (relative to a defined criterion), sensitivity of the model, stability of the model, etc. are available. [ABSTRACT FROM AUTHOR]

The article presents a simulation model of a queuing system (QS) with a queue and relative priority, which can be used to manage the reliability of transport systems under resource constraints. The developed simulation model combines agent and discrete-event simulation principles and allows studying queuing systems in terms of establishing regularities: probabilities (service, failure, pushout), time delays (waiting in a queue, under service), queue sizes, order of queue formation upon arrival of consumers of different priority. As a result of the research, dependencies were obtained for the probability of servicing higher priority consumers depending on the intensities of their arrival and service; probabilities of servicing lower priority consumers depending on the intensity of service and servicing of higher priority consumers; the probability of "pushing out" lower priority consumers from the QS by higher priority consumers depending on service intensities and the arrival of high priority consumers. [ABSTRACT FROM AUTHOR]

The article discusses some common mathematical models of counterterrorism and acts of unlawful interference with protected objects. The use of methods of queuing theory of Markov and nonMarkov types for modeling the counteraction of security personnel by a malicious group with a random number of criminals in a group and different ways of organizing the actions of such personnel is proposed. [ABSTRACT FROM AUTHOR]

An obituary for economist, statistician and financier Ivan Stanislavovich Blioh is presented.

The article discusses the use of decision support systems (DSS) for the effective management of forces for fire departments in Ukraine. It mentions on the creation of mathematical models to evaluate the use of DSS and the process for its recommendation. It states on the use of the method of production systems to create an information model of emergency.

Salmonella enterica is one of the most common human pathogens associated with fresh produce outbreaks. The present study suggests that expression of BcsZ, one of the proteins in the bcs complex, enhances the survival of Salmonella Typhimurium on parsley. BcsZ demonstrated glucanase activity with the substrates carboxymethylcellulose and crystalline cellulose, and was responsible for a major part of the S . Typhimurium CMCase activity. Moreover, there was constitutive expression of BcsZ, which was also manifested after exposure to plant polysaccharides and parsley-leaf extract. In an in-planta model, overexpression of BcsZ significantly improved the epiphytic and endophytic survival of S . Typhimurium on/in parsley leaves compared with the wild-type strain and bcsZ null mutant. Interestingly, necrotic lesions appeared on the parsley leaf after infiltration of Salmonella overexpressing BcsZ, while infiltration of the wild-type S . Typhimurium did not cause any visible symptoms. Infiltration of purified BcsZ enzyme, or its degradation products also caused symptoms on parsley leaves. We suggest that the BcsZ degradation products trigger the plant's defense response, causing local necrotic symptoms. These results indicate that BcsZ plays an important role in the Salmonella -plant interactions, and imply that injured bacteria may take part in these interactions., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Fratty, Shachar, Katsman and Yaron.)

Vascular endothelial growth factor A (VEGF-A) is a secreted protein that stimulates angiogenesis in response to hypoxia. Under hypoxic conditions, a non-canonical long isoform called L-VEGF is concomitantly expressed with VEGF-A . Once translated, L-VEGF is proteolytically cleaved to generate N-VEGF and VEGF-A. Interestingly, while VEGF-A is secreted and affects the surrounding cells, N-VEGF is mobilized to the nucleus. This suggests that N-VEGF participates in transcriptional response to hypoxia. In this study, we performed a series of complementary experiments to examine the functional role of N-VEGF. Strikingly, we found that the mere expression of N-VEGF followed by its hypoxia-independent mobilization to the nucleus was sufficient to induce key genes associated with angiogenesis, such as Hif1α, VEGF-A isoforms, as well as genes associated with cell survival under hypoxia. Complementarily, when N-VEGF was genetically depleted, key hypoxia-induced genes were downregulated and cells were significantly susceptible to hypoxia-mediated apoptosis. This is the first report of N-VEGF serving as an autoregulatory arm of VEGF-A. Further experiments will be needed to determine the role of N-VEGF in cancer and embryogenesis.

Anticoagulant treatment for acute myocardial infarction (AMI) and pericardial effusion is controversial, since the treatment might cause hemopericardium and tamponade. On the other hand, anticoagulants are strongly indicated in many situations in AMI, including: left ventricular thrombus, unstable angina, severe heart failure, deep vein thrombophlebitis, pulmonary embolism, atrial fibrillation, as part of thrombolytic treatment, and during cardiac catheterization. We describe a 70-year-old man who presented with both pericardial effusion and a left ventricular thrombus 3 weeks after an extensive, anterior wall AMI. Anticoagulants and corticosteroids were administered simultaneously under hemodynamic and echocardiographic monitoring without complications. It is our impression that anticoagulant treatment is safe in patients with pericardial effusion.

Microsomal membranes from chick embryo epiphyseal cartilage were fractionated by equilibrium sucrose-density-gradient centrifugation and assayed for GlcA (glucuronic acid) transferase I (the enzyme that transfers GlcA from UDP-GlcA to Gal-Gal-Xyl of proteochondroitin linkage region), for comparison with GlcA transferase II (the GlcA transferase of chondroitin polymerization). Gal(beta1-3)Galbeta1-methyl (disaccharide) and GalNAc(beta1-4)GlcA(beta1-3)GalNAc(beta1-4) GlcA(beta1-3)GalNAc(pentasaccharide) were used respectively as acceptors of [14C]GlcA from UDP-[14C]GlcA. Distributions of the two GlcA transferase activities in the sucrose-density-gradient fractions were compared with each other and with the previously reported distribution of the activities of Gal transferases (UDP-Gal to ovalbumin, and to xylose of the proteochondroitin linkage region) and GalNAc (N-acetylgalactosamine) transferase II of chondroitin polymerization. The linkage-region GlcA transferase I had a dual Golgi distribution similar to that of chondroitin-polymerizing GlcA transferase II and distinctly different from the distribution of linkage-region Gal transferases I and II, which were found exclusively in the heavier fractions. Solubilized GlcA transferase I was partly purified by sequential use of Q-Sepharose, heparin-Sepharose and wheatgerm agglutinin-agarose and was accompanied at each step by some of the GlcA transferase II activity. Both GlcA transferase I and II bound to the Q-Sepharose as though they were highly anionic. However, treatment with chondroitin ABC lyase eliminated the binding while markedly decreasing enzyme stability. The enzyme activities could not be reconstituted by adding chondroitin or chondroitin pentasaccharide to the chondroitin ABC lyase-treated enzymes. Incubation of the partly purified enzymes with both UDP-GlcA and UDP-GalNAc resulted in a 40-fold greater incorporation than with just one sugar nucleotide, indicating the presence of bound, nascent proteochondroitin serving as the acceptor for chondroitin polymerization. These results, together with the membrane co-localization, indicate that GlcA transferase I and GlcA transferase II occur closely together with nascent proteochondroitin at the site of synthesis and that this complex with the nascent proteochondroitin stabilizes both enzymes during purification.

Mouse mastocytoma cells were cultured with brefeldin A in medium containing [35S]sulfate and [3H]glucosamine in order to determine the effects of this fungal metabolite on the formation of chondroitin 4-sulfate by these cells. There was a marked reduction in the incorporation of [35S]sulfate into the glycosaminoglycan which was approximately equal to the reduction in the incorporation of [3H]hexosamine into the same molecule. The chondroitin 4-sulfate chain size was greatly diminished, while the number of chains appeared to remain relatively constant, indicating that the brefeldin A partially disrupted the polymerizing system, but had little effect upon movement of the nascent proteochondroitin to the site for chondroitin polymerization and sulfation.

Kinetic description of the changes of free radical concentration in Geren tumour tissue and in the tissues of liver, lungs, brain at chemotherapeutic application of licopine, selenium and cyclophosphane was obtained by ESR method. Licopine application decreases free radical concentration in the tumour (after the stage of a short-time rise). Similar effects during some periods of the action of carotinoids and of a valuable inhibitor of oxidation--selenium, as well as the citostatics of cyclophosphane allow to suggest that the application of the drug of vitamine A group is expedient in tumour therapy.

Weekly consultations have been offered to general public at the Institute since 1982. This resulted in a spontaneous distribution of patients into high-risk groups on the basis of psychological considerations. The rate of neoplasm detection has grown to 4.2%, while that of gynecological malignancies--to 7.34%, which marks a considerable increase as compared to traditional screenings (0.03-0.06%). The said consultations have assured sizeable economic gains.