Multimode fiber bandwidth prediction based on preform profile

A new technique is suggested for multimode fiber bandwidth prediction based on a preform profile. It allows one to calculate the output pulse distortion and allows the bandwidth of a fiber to be drawn dependent on the excitation conditions under which it will operate. It is shown that the accuracy of the bandwidth prediction for 1.5- to 2.5-km fibers is about 10%, the bandwidth being 1-1.5 GHz/km. To achieve this accuracy it is necessary that the excitation conditions and differential mode attenuation be exactly reproduced in the calculation. The profile variations along the length should not be considerable. The prediction technique was adapted to the P101 Preform Analyser (York Technology) and can replace alpha-approximation curve-fitting during routine manufacture of multimode preforms.     

The Kurosh problem,height theorem,nilpotency of the radical,and algebraicity identity

This paper is devoted to relations between the Kurosh problem and the Shirshov height theorem. The central point and main technical tool is the identity of algebraicity. The main result of this paper is the following. Let A be a finitely generated PI-algebra and Y be a finite subset of A. For any Noetherian associative and commutative ring {ie125-01}, let any factor of R ⊗ A such that all projections of elements from Y are algebraic over π(R) be a Noetherian R-module. Then A has bounded essential height over Y. If, furthermore, Y generates A as an algebra, then A has bounded height over Y in the Shirshov sense. This paper also contains a new proof of the Razmyslov-Kemer-Braun theorem on radical nilpotence of affine PI-algebras. This proof allows one to obtain some constructive estimates. The main goal of the paper is to develop a “virtual operator calculus.” Virtual operators (pasting, deleting, and transfer) depend not only on an element of the algebra but also on its representation. __________ Translated from Fundamentalnaya i Prikladnaya Matematika, Vol. 13, No. 2, pp. 3–29, 2007.     

Catalytic syntheses of poly cyclic compounds based on norbornadiene-2,5 in the presence of nickel complexes: III. Cyclic dimerization of norbornadiene-2,5 in the presence of organophosphorus additives

The cyclodimerization of norbornadiene-2,5 (NBD) catalyzed by the systems formed on the basis of bis(ηy³-allyl)nickel and organophosphorus compounds and the process kinetics are studied. The formation rate of all products follows the overall second-order rate law: first order with respect to the catalyst and NBD. The addition of phosphines and phosphites substantially decreases the reaction rate compared to that in nickel systems containing no organophosphorus additives. The influence of the phosphine ligand structure and temperature on the ratio of the reaction products is studied. The blocking of one coordination site on the nickel atom changes the process kinetics. The loss of two vacancies results in the loss of the catalytic activity of the system. A mechanism explaining the stoichiometry and composition of the reaction products is proposed.     

An efficient data format for mass spectrometry-based proteomics

The diverse range of mass spectrometry (MS) instrumentation along with corresponding proprietary and nonproprietary data formats has generated a proteomics community driven call for a standardized format to facilitate management, processing, storing, visualization, and exchange of both experimental and processed data. To date, significant efforts have been extended towards standardizing XML-based formats for mass spectrometry data representation, despite the recognized inefficiencies associated with storing large numeric datasets in XML. The proteomics community has periodically entertained alternate strategies for data exchange, e.g., using a common application programming interface or a database-derived format. However, these efforts have yet to gain significant attention, mostly because they have not demonstrated significant performance benefits over existing standards, but also due to issues such as extensibility to multidimensional separation systems, robustness of operation, and incomplete or mismatched vocabulary. Here, we describe a format based on standard database principles that offers multiple benefits over existing formats in terms of storage size, ease of processing, data retrieval times, and extensibility to accommodate multidimensional separation systems.     

Growth of KTiOPO<Subscript>4</Subscript> crystals doped with zinc and studies of their physical properties and specific structural features

A series of potassium titanyl phosphate single crystals doped with zinc (KTP: Zn) is grown by spontaneous flux crystallization. Their properties and the way the additive is implanted in the crystal lattice are studied. The inclusion of zinc atoms in the KTP structure is evidenced by the data of chemical analysis and the results of studies of electrophysical properties (the growth of conductivity and increase of relaxation anomalies). Precision X-ray diffraction studies of KTP: Zn single crystals reveal changes in the channel of the structure which correlate with the physical properties of this crystal series. No substitution of zinc atoms for titanium, phosphorus, or potassium atoms is found in the structure. Zinc atoms can be located at structural defects, domain walls, and the crystal surface.     

Thermal oxidation and photo- and biodestruction of the statistical copolymer of ethylene with carbon monoxide

Thermal and photooxidation of the statistical copolymer of ethylene containing 1.5% carbonyl units -C(O)- by molecular O₂ was studied at 160–200°C in the presence and absence of phenyl-β-naphthylamine (PNA) antioxidant. The incorporation of a small number of -C(O)- groups into the polyethylene chain insignificantly decreased the rate of thermal (dark) oxidation but substantially accelerated oxidation under the action of light. At the same time, the oxidation of the copolymer occurred at a lower rate than the oxidation of pure polyethylene (PE), which was evidence of an important role played by intramolecular oxidation chain propagation in PE, which is disturbed already at a comparatively low fraction of foreign units. Phenyl-β-naphthylamine noticeably decelerated oxidation. The rate of polymer biodestruction was much higher than the rate of PE biodestruction. The influence of biodestruction on the physicomechanical properties of samples was studied by ultrasonic microscopy. The velocity of sound propagation in PE was somewhat lower compared with the ethylene-carbon monoxide copolymer (ECO). Clearly, the introduction of a small amount of CO molecules into the polyethylene chain changed the microstructure of PE. The structure of ECO was more ordered and denser because of plasticization by metabolites.     

The problem of controlling resources on network graphs as an optimal control problem

The problem of optimal distribution of resources dedicated to a certain complex of inter-related tasks according to the criterion of minimum execution time of all tasks is described. A reenterable (reusable) resource is considered instead of a traditional separable-type resource supposing a fixed distribution among tasks. The problem is formalized in direct static and dynamic settings. The latter is a classical performance optimal control problem. The correctness of the formalization is substantiated.     

q-Deformation of the Virasoro algebra and lattice conformal theories

A natural definition of the q-deformation of the Virasoro and superconformal algebras is suggesteded. New Liealgebraic symmetries describe a lattice version of the continual theory. A close link between the deformation constructed in this paper and the lattice version of the Faddeev-Takhtadjian-Volkov Virasaro algebra is shown. 18 titles. Published inZapiski Nauchnykh Seminarov POMI, Vol. 235, 1900, pp. 217–227.