Continuity theorems for the M/M/1/nM/M/1/n queueing system

In this paper continuity theorems are established for the number of losses during a busy period of the $M/M/1/n$ queue. We consider an $M/GI/1/n$ queueing system where the service time probability distribution, slightly different in a certain sense from the exponential distribution, is approximated by that exponential distribution. Continuity theorems are obtained in the form of one or two-sided stochastic inequalities. The paper shows how the bounds of these inequalities are changed if further assumptions, associated with specific properties of the service time distribution (precisely described in the paper), are made. Specifically, some parametric families of service time distributions are discussed, and the paper establishes uniform estimates (given for all possible values of the parameter) and local estimates (where the parameter is fixed and takes only the given value). The analysis of the paper is based on the level crossing approach and some characterization properties of the exponential distribution.Comment: Final revision; will be published as i

Stochastic inequalities for single-server loss queueing systems

The present paper provides some new stochastic inequalities for the characteristics of the $M/GI/1/n$ and $GI/M/1/n$ loss queueing systems. These stochastic inequalities are based on substantially deepen up- and down-crossings analysis, and they are stronger than the known stochastic inequalities obtained earlier. Specifically, for a class of $GI/M/1/n$ queueing system, two-side stochastic inequalities are obtained.Comment: 17 pages, 11pt To appear in Stochastic Analysis and Application

Large closed queueing networks in semi-Markov environment and its application

The paper studies closed queueing networks containing a server station and $k$ client stations. The server station is an infinite server queueing system, and client stations are single-server queueing systems with autonomous service, i.e. every client station serves customers (units) only at random instants generated by a strictly stationary and ergodic sequence of random variables. The total number of units in the network is $N$. The expected times between departures in client stations are $(N\mu_j)^{-1}$. After a service completion in the server station, a unit is transmitted to the $j$th client station with probability $p_{j}$ $(j=1,2,...,k)$, and being processed in the $j$th client station, the unit returns to the server station. The network is assumed to be in a semi-Markov environment. A semi-Markov environment is defined by a finite or countable infinite Markov chain and by sequences of independent and identically distributed random variables. Then the routing probabilities $p_{j}$ $(j=1,2,...,k)$ and transmission rates (which are expressed via parameters of the network) depend on a Markov state of the environment. The paper studies the queue-length processes in client stations of this network and is aimed to the analysis of performance measures associated with this network. The questions risen in this paper have immediate relation to quality control of complex telecommunication networks, and the obtained results are expected to lead to the solutions to many practical problems of this area of research.Comment: 35 pages, 1 figure, 12pt, accepted: Acta Appl. Mat

Prevention of autonomic disadaptation in service members

The autonomic nervous system (ANS) is the main regulator of maintaining homeostasis and organism adaptation to changes in the environment. Most often, autonomic dysfunction occurs under the conditions of chronic psychoemotional stress. To prevent emotion dysregulation and stress-related disorders in service members, the state of the autonomic nervous system was assessed by examining 145 military servicemen, considering the initial autonomic tone, autonomic reactivity and autonomic support of the individual. In most subjects there was tension and dysfunction of the ANS, which allowed us to recommend a more thorough study of its three main components in order to identify autonomic disorders and the allocation of these persons to the risk group for psychosomatic pathology. Вегетативна нервова система (ВНС) є головним регулятором підтримки гомеостазу та пристосування організму до змін зовнішнього середовища. Найбільш часто вегетативна дисфункція виникає в умовах хронічного психо-емоційного стресу. Для запобігання виникнення дизрегуляції та стрес-асоційованих розладів у військових було проведено оцінку стану вегетативної нервової системи шляхом обстеження 145 військових з урахуванням вихідного вегетативного тонусу, вегетативної реактивності та вегетативного забезпечення діяльності особи. У більшості досліджуваних осіб відзначалися напруженість і дисфункція ВНС, що дозволяє рекомендувати більш ретельне дослідження трьох її основних складових з метою виявлення вегетативних порушень і виділенню цих осіб в групу ризику по виникненню психосоматичної патології. Вегетативная нервная система (ВНС) является главным регулятором поддержания гомеостаза и приспособления организма к изменениям внешней среды. Наиболее часто вегетативная дисфункции возникает в условиях хронического психо-эмоционального стресса. Для предотвращения возникновения дизрегуляции и стрессассоциированных расстройств у военных была проведена оценка состояния вегетативной нервной системы путем обследования 145 военных с учетом исходного вегетативного тонуса, вегетативной реактивности и вегетативного обеспечения деятельности человека. В большинстве исследуемых лиц отмечались напряженность и дисфункции ВНС, что позволяет рекомендовать более тщательное исследование трех ее основных составляющих с целью выявления вегетативных нарушений и выделению этих лиц в группу риска по возникновению психосоматической патологии

The effective bandwidth problem revisited

The paper studies a single-server queueing system with autonomous service and $\ell$ priority classes. Arrival and departure processes are governed by marked point processes. There are $\ell$ buffers corresponding to priority classes, and upon arrival a unit of the $k$th priority class occupies a place in the $k$th buffer. Let $N^{(k)}$, $k=1,2,...,\ell$ denote the quota for the total $k$th buffer content. The values $N^{(k)}$ are assumed to be large, and queueing systems both with finite and infinite buffers are studied. In the case of a system with finite buffers, the values $N^{(k)}$ characterize buffer capacities. The paper discusses a circle of problems related to optimization of performance measures associated with overflowing the quota of buffer contents in particular buffers models. Our approach to this problem is new, and the presentation of our results is simple and clear for real applications.Comment: 29 pages, 11pt, Final version, that will be published as is in Stochastic Model

Features of lecture preparation from the subject “Child's surgery, orthopaedy and traumatology” in the Ukrainian high medical institutions

In the article review discusses topical issues towards numerous forms of presentation as well as lecture in the course from “Child’s surgery, orthopaedy and traumatology”: basic principles of lecture material preparing, basic points of the lecture standardization, modern technological capabilities providing while preparing lectures, motivational capabilities of lectures for students. High requirements for professional training on the subject, the information technologies accelerated development, ability for scientific and pedagogical activity - such requirements should be carried out for University lecturer. Today should be appointed the skills focused on a foreign language and a communication with native speakers. Lecture from “Child’s surgery, orthopaedy and traumatology” should be focused on an audience's attention for a long period of time. Therefore, careful preparation on the lecture, accumulation of new scientific data, choice of modern technologies for presentation, adaptation of lectures in order to suit the audience, connection between theoretical topics with practical assignment should be carried out on the practical clinical activities, individual approach of the lecturer as well as themes presentation are key components for teachers’ activity during lecture preparation and presentation of material

Influence of Sanitary – Domestic Conditions in the Rural Settlements of Dnepropetrovsk Region on the Peasants’ Healh

Purpose of research: implementation results of sociological survey to the practice of hygienic researches at the subjective estimation of the drinking water quality and sanitary conditions of people’s life. Materials and methods. At our study was used standardized "Questionnaire survey about quality of piped drinking water, which enters to the building (apartment)", which contained 25 questions. In the sociological survey were participated 150 respondents. Results. Peasants of Dnepropetrovsk region considered that the following indicators of drinking water quality impact on their health: deterioration quality of piped drinking water, smell – 22.6%, color – 14.6 %, rust – 13.3 %, precipitate – 8.0 %, turbidity and suspended solids – 10.6 %, taste and aftertaste – 13.3 %, foam and impurities – 10.6 % (p<0.05). Some of peasants (14.6 %) have unsatisfactory sanitary conditions, living on 5 – 6 persons in 1 rooms flat (p<0.05). Conclusions. Results of sociological survey shown that among rural residents increased the demand for a consumption of pre-treated drinking water, due to the deterioration quality of tap water in the rural area. It was determined, that increased frequency of use the bottled drinking water – daily it was used by 13 rural respondents (17.3%), once a week – 21 respondents (28%), 2-3 times a week – 8 respondents (10.6%)

Scientifical-methodical background system of medical students’ education from discipline child's surgery, orthopaedy and traumatology in Ukraine

Improvement preparation of specialists is a national task, standing before specialists of a higher school. In the conditions of the higher medical education reformation and innovative transformations of the society in Ukraine increasing requirements to the quality of doctors’ preparation. Requirements to a quality of preparation doctors increasing constantly, that carried out to the search of new forms and methodologies of educational process. Standartization of educational process, using different forms of educating, should be focused on the maximal realization of self-preparation activity and initiativeness of students, which are laying on a basis of Bologna process. Future doctor is, foremost, a specialist, which must be able to make a decision oriented on the life and health of his patients. The important task at the creation of any program is development the system of estimation knowledge and skills of students in points. Current, intermediate and final control is documented in the individual plan of educational process of student. In this document, converting the amount of points is carried out estimations by a scale ECT. Fungal development in the area of medical knowledge and proposes of an innovative transformations of society should provide a new system of requirements and education tasks. Perfection of the teaching methods, development and progress of new forms of teaching, acquire on a modern stage an important value in the student preparation. On the condition of observance all enumerated requirements, after graduation from the institution, government should get a formed skilled specialist capable independently and together with colleagues to accept the self-weighted decisions in a certain real situation, using in their professional activity those high spiritual qualities, which chould formed and developed his teachers in the process of educating, taking into account changes in our society

Production Asymmetry Measurement of High Xt Hadrons in pp Collisions at 40 GeV

Single-spin asymmetries for hadrons have been measured in collisions of transversely-polarized 40 GeV/c proton beam with an unpolarized liquid hydrogen target. The asymmetries were measured for pi+-, K+-, protons and antiprotons, produced in the central region (0.02 < Xf < 0.10 and 0.7 < Pt < 3.4 GeV/c). Asymmetries for pi+-, K+- and antiprotons show within measurement errors the linear dependence on Xt and change a sign near 0.37. For protons negative asymmetry, independent of Xt has been found. The results are compared with those of other experiments and SU(6) model predictions.Comment: 25 pages (Latex), 12 Postscript figure

Scattering theory and ground-state energy of Dirac fermions in graphene with two Coulomb impurities

We study the physics of Dirac fermions in a gapped graphene monolayer containing two Coulomb impurities. For the case of equal impurity charges, we discuss the ground-state energy using the linear combination of atomic orbitals (LCAO) approach. For opposite charges of the Coulomb centers, an electric dipole potential results at large distances. We provide a nonperturbative analysis of the corresponding low-energy scattering problem