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The amplification of ultrashort signals in the range 2.7-3 um in active tellurite glass fibres with high Kerr nonlinearity and high concentration of erbium ions in the core is theoretically investigated under diode pumping at a wavelength of 0.975 um. The possibility of producing pulses with the energy [?]10 nJ and the duration smaller than 100 fs with [?]20 dB gain is shown. Moreover, using a specially developed iterative computer algorithm, the possibility of determining the intensity and phase of the generated pulses by measuring their fundamental spectra and two additional spectra obtained by means of nonlinear-optical conversion in short pieces of these optical fibres is demonstrated. Optical fibre samples are made of high-purity TeO2 - ZnO - La2O - Na2O glasses with 1021 cm-3 concentration of erbium ions in the core and a low content of hydroxyl groups that causes small losses in the spectral range under consideration. The group velocity dispersions, effective mode fields, nonlinear coefficients and field overlap integrals of the LP01 fundamental modes with a doped core for optical fibres with different core diameters are calculated, and the emission and absorption cross sections are calculated basing on the experimental luminescence spectrum. The optimal parameters of the amplifier are determined by numerically modelling the dynamics of ultrashort pulses using the measured and calculated characteristics.

A simple design of a fiber laser system for generating high-quality pulses with a duration of order 100 fs with ultrabroad wavelength tunability in the 2–5 μm range is discussed. This design incorporates conventional fs near-IR lasers and specially developed tungstate–tellurite fibers with two zero-dispersion wavelengths (ZDW) and relies on nonlinear wavelength conversion via either soliton self-frequency shift (SSFS) or red-shifted dispersive wave (DW) generation. The fiber parameters needed for such optical conversion have been scanned numerically and showed a possibility of SSFS beyond 4 μm and of DW generation beyond 5 μm. We have also studied and prepared tungstate–tellurite glasses and preforms that are highly stable against crystallization, exhibit extremely low level of hydroxyl groups absorption, and from which the suspended-core two-ZDW fibers can be manufactured.

A turnkey fiber laser source generating high-quality pulses with a spectral sech shape and Fourier transform-limited duration of order 100 fs widely tunable in the 1.6–2.65 μm range is presented. It is based on Raman soliton self-frequency shifting in the suspended-core microstructured TeO_2-WO_3-La_2O_3 glass fiber pumped by a hybrid Er/Tm fiber system. Detailed experimental and theoretical studies, which are in a very good agreement, of nonlinear pulse dynamics in the tellurite fiber with carefully measured and calculated parameters are reported. A quantitatively verified numerical model is used to show Raman soliton shift in the range well beyond 3 μm for increased pump energy.

We report the preparation of a high-purity optical-quality four-component glass of composition 68TeO2 -- 22WO3 -- 8La2O3 -- 2Bi2O3, containing (2.7+-0.5)x10-5 mol % OH groups. Its refractive index has been determined in the range 0.9 -- 5.45 mm using interference refractometry. The data are used to assess the dispersion and guidance characteristics of microstructured optical fibres potentially attractive for supercontinuum generation in the range 1 -- 5 mm

Objectives.Investigation was carried out within the framework of the large-scale international project “Persistent Toxic Substances (PTS), Food Security and Indigenous People of the Russian North” under RAIPON/AMAP/GEF aegis. Objectives of the project are to obtain comprehensive information on exposure of indigenous populations to contaminants through food chains (and other sources), and to investigate the possible health effects connected to this exposure. Four regions of Russia are involved in the project: Kola Peninsula (Murmansk oblast), Nenetsk okrug (Pechora river basin), Taimyr Peninsula, Chukotka Peninsula. Methods.Questionnaire and paired sampling of maternal/cord blood among indigenous women at childbirth (more than 250 persons) as well as among general indigenous population (more than 1,400 persons), additionally breast milk sampling of lactating women (more than 50 persons) in Chukotka was conducted. About 700 blood samples have been analyzed at the Center for Environmental Chemistry, SPA “Typhoon” (Obninsk, Russia), the Regional Center “Monitoring of the Arctic”, RCMA (St. Petersburg, Russia), the Norwegian Institute for Air Research, NILU (Tromso, Norway) and at INSPQ (Sainte-Foy, Quebec, Canada). Results and Conclusions.On the whole, PTS in human blood of the Russian Arctic natives are similar to those in the coastal areas of Greenland and Canada, and for some POPs such as toxaphenes and mirex, these levels are lower.

Ellipsometric data on titanium oxide nanolayers synthesized by molecular layer deposition technique on oxidized Si(100) surface are discussed.

ZnTe and Cd1 – yZnyTe epilayers were grown on GaAs(111)Band GaAs(100) substrates by metalorganic chemical vapor deposition. The structural perfection and surface morphology of the layers were investigated by double-crystal x-ray diffraction and scanning electron microscopy. The effect of deposition conditions on the growth rate, zinc content (y), surface morphology, and structural perfection of the epilayers was studied. The results suggest that the optimal structures for depositing HgCdTe(111)Band HgCdTe(100) are CdTe(111)B/GaAs(111)Band CdTe(100)/ZnTe(100)/GaAs(100), respectively.

The number of pseudoscalar mesons in the mass range from 1400 to 1500 MeV/c2has been a subject of considerable interest for many years, with several experiments having presented evidence for two closely spaced states. A new measurement of the reaction π−p→K+K−π0nhas been made at a beam energy of 18 GeV. A partial wave analysis of the K+K−π0system shows evidence for three pseudoscalar resonances, η(1295), η(1416), and η(1485), as well as two axial vectors, f1(1285), and f1(1420). Their observed masses, widths and decay properties are reported. No signal was observed for C(1480), an IGJPC=1+1−−state previously reported in φπ0decay.

Abstract: The evolution of an ensemble of intense vortices in the β-plane is numerically simulated. In the process of evolution, vortices interact either directly or by means of the Rossby waves emitted by them. We show that the mean displacements of vortices of the ensemble along the meridian and, as a result, their energy losses are lower than for the isolated vortices evolving in the β-plane. This means that they are more stable than the isolated vortices. In addition, for vortices in the ensemble, the theoretical dependence of the energy of a vortex on its displacement from the initial latitude obtained for the motion of an intense isolated vortex in the β-plane is in good agreement with the experimental data.

It is shown that a solution of the form R(ν)=0 (R is the space-time curvature) exists for a vacuum solution (the field fluctuations are assumed zero, and only the ground state with the minimum effective potential energy remains) in the initial stage with consideration of the effect of spontaneous symmetry breaking for a scalar field with the “wrong sign” of the mass term and the conformal factor. For a spherically symmetric metric in vacuum, a solution increasing as a square of the distance and proportional to the square of the Higgs boson mass exists.

Abstract: Within the framework of a two-layer model, we consider the process of, formation of livel in a closed basin under the action of a source with constant flow rate located on its boundary in the upper layer. The response of the level of the basin to the inflow of liquid is observed in the form of the baroclinic and barotropic modes. The baroclinic mode, has the form of an edge wave for which the deviation of level is positive for the upper layer and negative for the lower layer. The barotropic component of the level is almost spatially homogeneous and its intensity increases with time. The increase in the volume of the upper layer caused by the inflow of liquid on the boundary is almost completely attained in the barotropic mode. In the lower layer, the increase in the volume attained in the barotropic mode is completely compensated by the baroclinic edge wave.

Investigations were carried out into the materials for blanks of side milling cutters produced from high-speed steel powder by hot upsetting ring-shaped porous blanks with the centripetal flow of the material. A method of evaluating the quality of material on the basis of the density and specific work of failure of specimens, cut from the discs in different areas and in different directions, was developed and applied for this purpose. The use in the blank of a central insert produced from rolled structural steel results in higher properties (“the head” effect). The results of testing the durability of cutters with working elements produced from high-speed steel powder show that their durability decreases less rapidly with increasing cutting speed than that of the cutters made of rolled material.

The decayf1(1285)??0(770)? was studied at VES spectrometer of IHEP. Clear signal off1(1285) is seen in the effective mass spectrum of the p+p-? system in the reaction p-?N?p+p-p-?N at the momentum . The branching fraction of decayf1(1285)??0(770)? has been found to be $$BR(f_1 (1285) \to \rho ^0 (770)\gamma ) = (2.8 \pm 0.7(stat) \pm 0.6(syst)) \cdot 10^{ - 2} .$$ The ratio of the helicity amplitudes for ?0 meson in its rest frame was determined by the analysis of angular distributions: $$\rho _{00} /\rho _{11} = 3.9 \pm 0.9(stat) \pm 1.0(syst).$$

The radiative decayη′→π+π−γ has been studied with the statistics of ≃2000 events. Different ways of describingmππ distribution are considered. It is shown that if the dominating contribution to this process is made by the decay channel η′→ργ, then the generally accepted ways of describing the ρ peak do not agree with experimental data.

Abstract: The paper considers some general laws of the dynamics of an intensive isolated eddy interacting with background vorticity, namely, the latitudinally varying Coriolis parameter, bottom topography, and a mean inhomogeneous flow. Using experimentally derived numerical data, we show the eddy’s typical behaviour in three different situations.

The reactions of baryon diffractive productionp+N?(pK+K-)+N, p+N?(p?)+N, p+N?[?(1520)K+]+N p+N?[S(1385)oK+]+N in the 70 GeV proton beam were studied. Very sensitive upper limits for the production cross sections of heavy narrow cryptoexotic baryon resonances with hidden strangeness were obtained.

In the experiments at the SPHINX facility in the 70 GeV proton beam of the IHEP accelerator the diffractive production reactionsp+N→[Σ(1385)0K+] +N andp+N→[Σ(1385)0K+]+N+ (neutral particles) were studied. In the effective mass spectra of the [Σ(1385)0K+] system in these processes there were no signals from the anomalously narrow baryon stateNϕ (1960) which had been observed earlier in the measurement at the BIS-2 setup.

Abstract: This paper discusses the diffraction of a low-frequency Kelvin wave (having a frequency comparable to that of a baroclinic Rossby wave) at the apex angle. The problem is handled, with the Coriolis parameter being variable, by expanding into series over the minor parameter ε characteristic of the ratio between the deformation radius and the length of an incident wave travelling along a latitudinal shore. An analytical expression has been derived for a wave translating along meridional shore. It is demonstrated that when the latitudinal shore is located above the critical latitude, the energy flux through the horizontal cross-section transported by the wave coincides with the corresponding flux in the incident wave. If, on the other hand, it is situated below the critical latitude, then part of the energy is consumed by offshore Rossby waves.

The technological conditions of obtaining powder materials exert a decisive influence on the course of the processes of concrescence, and consequently on the properties of the obtained specimens. If cooling and oxidation in the transfer of compacts from the furnace to the forging die are reduced to a minimum, then the optimal medium for sintering and hot repressing is a reducing medium, e.g., sharply dried hydrogen or DA. The accompanying removal of admixtures from the surfaces of open pores facilitates the processes of concrescence.

The quality of concrescence is a factor determining the properties of powder material. High-quality concrescence of particles is promoted by shear strains, both at the stage of SCP and of HF. The highest indicates K1C are encountered in sintered and hotforged materials from reduced powder PZh2M3 with ramified shape of the particles.

The surfaces of macro-, micro-, and submicropores of specimens of all groups are more strongly enriched with impurity elements than the interparticle boundaries.

In the hot re-pressing of porous P/M preforms with elements of direct and reverse extrusion, in the initial stage work is expended mainly in the densification of the P/M material and then, after this has been completed, in extrusion. Initially, extrusion may take place both with and without the P/M material experiencing a loss of density. The probability of loss of density increases on passing from static to shock loading and from direct to reverse extrusion, and also with increasing D/d ratio. In the range of phase transformation temperatures stepwise reductions in the density of the material of the extruded element and its length are observed. The density of the bulk of the specimen is sensitive to temperature changes only at W < Wmax.

The technology of heat forming of powder products with lengthwise grooves has been developed, which consists of pressing the working elements of a tool in the body of a preheated porous blank. The influence of porosity, shape, the degree of preliminary plastic deformation, and the geometric parameters of the porous blank on the area of the textured zone of product lugs has also been examined. The maximum values are attained when blanks with a porosity of 15% (without preliminary compression) and 20–25% (with compression) are used.

A technology is developed for making monometallic and bimetallic compacts for the production of disk-type milling cutters based on powder high-speed steel. The main operation in the technology is the hot upsetting of porous ring-shaped semifinished products, with the material flowing toward the center of the product. The article describes the methods used to fabricate the compacts from powder high-speed steel and protect against oxidation during heating, as well as the design of a disk-type milling cutter with a replaceable bimetallic ring. The requirements of the main manufacturing operations are presented.

A study has been made of the character of the redistribution of volumes of a porous blank during hot forging with elements of extrusion; the feasibility is shown of controlling the process with the aim of ensuring that certain volumes of material occupy the required positions. It has been confirmed by experiment that the process of hot forging of porous materials with elements of extrusion involves more than one stage. The character of pressing pressure variation in various stages has been determined. In pressing in conical dies densification of central volumes of material lags slightly behind that of peripheral regions. For specimens of the geometric parameters investigated, the width of the peripheral blank zone, which in the steady-state extrusion stages moves parallel to the compressing part of the die, is (0.15–0.20)Dc. The degree of deformation and the redistribution of volumes of material in peripheral layers are affected mainly by the temperature conditions of the pressing process and to a much smaller extent by the starting blank porosity.

Results of the partial-wave analysis of the reactionπ−p→π+π−π0n, studied aton 2·105event statistics, are presented. Masses and widths ofa2(1320) andω3(1670) mesons are measured, as well as differential cross-sectionsdσ/dtin thea2andω3regions. It is shown that the relative phase between 2+and 3−is consistent with the two-resonance description. The estimated limits for theπ0(1300),π2(1670),ω1(1420) andω1(1600) cross sections are also presented.

Abstract: The motion of an intensive cyclonic eddy on a β-plane in the presence of a zonal non-uniform flow is studied numerically in the, framework of an equivalent-barotropic quasi-geostrophic model. The main aspects influencing the cyclone motion, namely, the velocity of the surrounding flow and the gradient of potential vorticity gradient, are analysed. The main types of trajectories of tropical cyclones are thence simulated.

Eight Triticum species are found in Armenia and due to their great diversity they can be divided into a number of subspecies and botanical varieties. This also holds true for agricultural properties such as yield, growth habit, winter hardiness, straw strength and resistance to fungal diseases.

Hybrids naturally arising between Triticum species and between Triticum species and species of Secale and Aegilops are found in wheat fields in Transcaucasia. This continuous exchange of genetic material will yield new genotypes which may be useful in breeding.