Asymptotic analysis of queues in multiple-access computer networks

The paper considers local-area computer networks with a protocol that supports carrier-sense multiple access with instantaneous conflict detection and is a generalization of slotted ALOHA. An approach based on recurrent processes is applied to analyze the asymptotic behavior of the number of waiting calls under conditions of low retrial rate.Translated from Kibernetika i Sistemnyi Analiz, No. 4, pp. 54–61, July–August, 1991.     

The carcinogenic effect of 5-bromodeoxyuridine and its amplification by x-rays in rats

5-bromodeoxyuridine (BUdR) injected to rats in the neonatal period is shown to produce a pronounced carcinogenic effect which brings about the appearance of various benign and malignant tumours. Exposure of females to X-ray total-body irradiation (1.5 Gy) was followed by intensification of the carcinogenic effect of BUdR. Assuming that this pyrimidine analog reacts solely with DNA substituting thymidine during DNA synthesis and induces point mutations due to tautomerization, the data obtained demonstrate the possibility of tumour induction by a selective DNA perturbation.     

Transport properties of critical dilute solutions

On the basis of the isomorphism of critical phenomena, the behavior of transport properties of binary mixtures in the vicinity of the vapor-liquid critical line is considered. In particular, the renormalization of the singularity of the thermal conductivity in dilute critical solutions has been analyzed in detail. It is shown that the behavior of the thermal conductivity is determined by the critical background, i.e., the fluctuation-induced regular part, which diverges at the critical point of a solvent.     

Encoding Trees by Linear Recurrence Sequences

A unified encoding of ordered binary trees with integer-valued labels at their vertices is proposed using linear forms of neighboring members of linear recursive sequences of the form P_{n + 2} = a_{n + 2} P_{n + 1} + P, where P₁ = P₂ = 1; a₃ and a₄ … are natural numbers. Encoding and decoding procedures are simply implemented and use the recursive technique of direct pre-order depth-first tree traversal. A brief review of possible applications of the proposed encoding in problems of tree processing and cryptographic symmetric encryption is presented.     

Heuristic Algorithms for Determination of Canonical Forms and Grammatical Characteristics of Words

Algorithms are developed that determine canonic forms and grammar categories from individual words and the vocabulary of a text. Algorithms are proved to be highly efficient. The accuracy of determination directly depends on the length of the text.     

Indices of the effectiveness of information protection in an information interaction system for controlling complex distributed organizational objects

In this paper, we present some indices for evaluating the effectiveness of information protection in an information interaction system when controlling complex distributed organizational objects and proposing a technique for determining these indices. The technique is based on a stochastic representation of the flow of destructive actions that affect the information interactions among controllers of the elements of a distributed organizational object.     

W-band Imaging Detector with Incoherent Illumination

A single-pixel imaging detector operating in W-band is described. It is based on a wideband receiving module using direct detecting circuitry and a transmitting unit with a pulse-modulated wideband noise source. The detector consists of a single transmit / receive channel mounted on a programmable scanner in an X-Y plane configuration. A LabView interface integrated with MatLab is employed allowing image continues reconstruction line-by-line. The application of incoherent illumination generated by a frequency-limited noise source improves image quality compared with conventional coherent sources used in active imagers. An image processing algorithm using a binary threshold level is considered with some examples of image reconstruction employing the detector.