Hollow core Bragg fiber with antiresonant intermediate layer

By means of the transfer matrix method, the optical properties of fibers with a distinct intermediate layer between a hol-low core and periodic cladding are calculated. The periodic cladding consists of two types of the alternating layers. The intermediate layer has distinct thickness and refractive index. Depending on these parameters, the fiber can work in the single-mode or multi-mode regimes. In the multi-mode regime, the optical loss of the smallest loss mode can be de-creased by increasing the thickness of the layer. In the single-mode regime, the optical loss falls with a rise in the refrac-tive index of the intermediate layer. The optical properties of the fiber are determined by the antiresonance reflection from the intermediate layer and the Bragg reflection from the periodic cladding. Selecting the parameters of the interme-diate layer, the optical loss of the fiber in the single-mode regime can be reduced by an order of magnitude over the loss of the traditional Bragg fiber.Comment: 9 pages, 4 figure

Standards Maturity Variance Regarding the TCP MD5 Signature Option (RFC 2385) and the BGP-4 Specification

The IETF Standards Process requires that all normative references for a document be at the same or higher level of standardization. RFC 2026 section 9.1 allows the IESG to grant a variance to the standard practices of the IETF. This document explains why the IESG is considering doing so for the revised version of the BGP-4 specification, which refers normatively to RFC 2385, "Protection of BGP Sessions via the TCP MD5 Signature Option". RFC 2385 will remain at the Proposed Standard level

Effective techniques for the formation of reader competence and their application in the classroom

In this article, we consider a number of basic principles that underlie the development of techniques for the formation of reader competence among students in the lessons of the Russian language and literature

An Improved Ultrasonic Technique for Three Dimensional Inclusions

Conventional C-scan ultrasonic techniques are excellent for imaging two dimensional defects such as delaminations, cracks, and plate type inclusions [1]. This technique is most effective when these defects are oriented parallel to the scanning plane. However, for three-dimensional inclusions difficulties are encountered when the conventional scanning technique is adopted. If one wants to reconstruct the three dimensional inclusion from generated C-scan images at different depths a significant amount of error is introduced in its size and shape. Even for a simple 3D object such as a sphere it is often difficult to accurately estimate its size and location from its C-scan generated image

Theoretical foundations of the formation of communicative competence among students in the process of teaching the Russian language and culture of speech

The article discusses the theoretical foundations of the formation of communicative competence among students-bunning students in the process of teaching the Russian language and speech culture

Magnetocaloric properties of Gd(Co1-xFex)2 compounds, with x ≤ 0.60

In this paper the results of specific magnetization and magnetocaloric effect (MCE) measurements for Gd(Co1-xFex)2 system upon the Co substitution by Fe for the x = 0 ÷ 0.60 range are presented. Phase composition was controlled by X-ray diffraction analysis. MCE has been studied within the temperature range of 300-850 K in magnetic fields up to 17 kOe by the magnetic entropy change calculation (ΔSm). It was found that in contrast to the previously studied R(Co-Fe)2 compounds where R = Dy, Ho, Er, an ordinary symmetrical peak of ΔSm(T) in the vicinity of TC is observed for presented samples. Additionally, the MCE comparison of Gd(Co0.88Fe0.12)2 with that for the isostructural Gd(Ni0.88Fe0.12)2 compound having a plateau-like ΔSm temperature dependence is given. The obtained results are discussed. © 2018 The Authors, published by EDP Sciences.This work has been supported by the State contracts No. 3.6121.2017/8.9 between U FU and the Ministry of Education and Science of Russian Federation

Ueber die copulirten Harnstoffe

n/

Quality and safety problems of sports nutrition products

The purpose of this work was to study the quality and safety of some sports nutrition products. The objects of study were sports nutrition products: protein bars of ‘ProteinBar’ (Russia) and ‘Bombbar’ (Russia); capsule forms of dietary supplements ω–3, ω–6, ω–9 firms ‘Sportline’ (Russia), ‘Multipower’ (Germany) and ‘Maxler’ (USA). According to the research results, the normalized safety indicators of the fat component of the studied products for sports nutrition (acid number and peroxide) are within acceptable values. The standardized safety indicators of the fat component do not fully reflect the safety requirements for the fat component of sports nutrition products, since there are no standards for the most important indicators of fat safety – the content of secondary oxidation products – copolymers insoluble in petroleum ether and epoxides. The results obtained in the course of the work showed that in almost all of the studied samples are content of epoxides (7.5–47.6 g -1 ) and secondary oxidation products – 1% or more