A MODEL OF A DISTRIBUTED INFORMATION SYSTEM BASED ON THE Z39.50 PROTOCOL

Based on the analysis of typical scenarios of information servers, the tasks that should be solved when organizing an access control system for distributed information resources are formulated. The possibilities of the Z39.50 technologies as the most suitable for building such a system are considered. Within the framework of this technology, three access control models are discussed, which differ in the degree of integration of information server functions with the Z39.50 technologies.The creation and support of distributed information systems and electronic libraries that integrate heterogeneous information resources and operate in various software and hardware environments requires special approaches to managing these systems. If the resources or data themselves can be managed locally, even for distributed information systems, then the task of managing access to distributed resources cannot be solved within the framework of local administration. The justification of the last thesis can be seen when considering typical scenarios of the information server, which we will describe below

Development of queries using the Z39.50 protocol in distributed information systems to support scientific and educational activities

Distributed information systems that support scientific and educational activities can work with various information systems. The main goal of creating a distributed information system supporting scientific and educational activities is to accelerate the pace and improve the quality of information exchange in the scientific environment. The paper considers technological methods for constructing models of information systems designed to support scientific and educational activities. The model under consideration is that the developed model of an information system for working with scientific materials should solve the problems of long-term storage of information, organizing data search by attributes, accumulating and replacing metadata. Based on the analysis of typical scenarios of information servers, the tasks that should be solved when organizing an access control system for distributed information resources are formulated. Within the framework of this technology, three access control models are discussed, which differ in the degree of integration of information server functions with the Z39.50 technologies. The creation and support of distributed information systems and electronic libraries that integrate heterogeneous information resources and operate in various software and hardware environments require special approaches to managing these systems. If the resources or data themselves can be managed locally, even for distributed information systems, then the task of managing access to distributed resources cannot be solved within the framework of local administration. The justification of the last thesis can be seen when considering typical scenarios of the information server, which we will describe below

SCALING PROPERTIES OF QUEUES WITH TIME-VARYING LOAD PROCESSES: EXTENSIONS AND APPLICATIONS

New computing and communications paradigms will result in traffic loads in information server systems that fluctuate over much broader ranges of time scales than current systems. In addition, these fluctuation time scales may only be indirectly known or even be unknown. However, we should still be able to accurately design and manage such systems. This paper addresses this issue: we consider an M/M/1 queueing system operating in a random environment (denoted M/M/1(R)) that alternates between HIGH and LOW phases, where the load in the HIGH phase is higher than in the LOW phase. Previous work on the performance characteristics of M/M/1(R) systems established fundamental properties of the shape of performance curves. In this paper, we extend monotonicity results to include convexity and concavity properties, provide a partial answer to an open problem on stochastic ordering, develop new computational techniques, and include boundary cases and various degenerate M/M/1(R) systems. The basis of our results are novel representations for the mean number in system and the probability of the system being empty. We then apply these results to analyze practical aspects of system operation and design; in particular, we derive the optimal service rate to minimize mean system cost and provide a bias analysis of the use of customer-level sampling to estimate time-stationary quantities.

Using the capabilities of the information server “Your Choice” in nutrition as a tool for forming the right choice in school meals

The authors consider the possibilities of using the information server “Your Choice” in the nutrition of students as an electronic tool for the formation of the correct choice of school ration dishes, food culture, data on the taste preferences of Moscow schoolchildren, an assessment of the consumption of words from the school menu according to the pre-order system with using an electronic server. The school menu was assessed according to the “Your Choice” pre-order system, which retains the positions of the most consumed, favorite dishes by children, so that the child eats the proposed range at school in full at each meal. Parents may know how to feed the child at home to replenish the daily physiological needs for nutrients and energy. According to preliminary results, a hygienic assessment of the proposed alternative diet options and a hygienic assessment of the existing forms of ordering rations in general educational institutions using the innovative electronic system for choosing an alternative food ration “Your Choice” by Moscow schoolchildren showed a higher eatability of the selected dishes up to 89-90%. The authors recommend using the digital system “Your Choice” to completeness the eatability of the proposed dishes, formation of correct eating habits, and assessment of schoolchildren’s nutrition. A comparative analysis of catering and existing menus with new developments (alternative meals for schoolchildren) showed that equipping a school canteen with gadgets and tablets helps to pass identification much faster when schoolchildren receive lunch in an educational institutions, compared to the usual payment and catering system.

A Single Mutation Increases the Thermostability and Activity of Aspergillus terreus Amine Transaminase

Enhancing the thermostability of (R)-selective amine transaminases (AT-ATA) will expand its application in the asymmetric synthesis of chiral amines. In this study, mutual information and coevolution networks of ATAs were analyzed by the Mutual Information Server to Infer Coevolution (MISTIC). Subsequently, the amino acids most likely to influence the stability and function of the protein were investigated by alanine scanning and saturation mutagenesis. Four stabilized mutants (L118T, L118A, L118I, and L118V) were successfully obtained. The best mutant, L118T, exhibited an improved thermal stability with a 3.7-fold enhancement in its half-life (t1/2) at 40 °C and a 5.3 °C increase in T5010 compared to the values for the wild-type protein. By the differential scanning fluorimetry (DSF) analysis, the best mutant, L118T, showed a melting temperature (Tm) of 46.4 °C, which corresponded to a 5.0 °C increase relative to the wild-type AT-ATA (41.4 °C). Furthermore, the most stable mutant L118T displayed the highest catalytic efficiency among the four stabilized mutants.