Transverse-momentum spectra in Au+Au and d+Au collisions at sqrt[s(NN)]=200 GeV and the pseudorapidity dependence of high-p(T) suppression

We present spectra of charged hadrons from Au+Au and d+Au collisions at sqrt[s(NN)]=200 GeV measured with the BRAHMS experiment at RHIC. The spectra for different collision centralities are compared to spectra from p+(-)p collisions at the same energy scaled by the number of binary collisions. The resulting ratios (nuclear modification factors) for central Au+Au collisions at eta=0 and eta=2.2 evidence a strong suppression in the high p(T) region (>2 GeV/c). In contrast, the d+Au nuclear modification factor (at eta=0) exhibits an enhancement of the high p(T) yields. These measurements indicate a high energy loss of the high p(T) particles in the medium created in the central Au+Au collisions. The lack of suppression in d+Au collisions makes it unlikely that initial state effects can explain the suppression in the central Au+Au collisions.     

Parametric continuation of the solitary traveling pulse solution in the reaction-diffusion system using the Newton-Krylov method

The matrix-free Newton-Krylov method that uses the GMRES algorithm (an iterative algorithm for solving systems of linear algebraic equations) is used for the parametric continuation of the solitary traveling pulse solution in a three-component reaction-diffusion system. Using the results of integration on a short time interval, we replace the original system of nonlinear algebraic equations by another system that has more convenient (from the viewpoint of the spectral properties of the GMRES algorithm) Jacobi matrix. The proposed parametric continuation proved to be efficient for large-scale problems, and it made it possible to thoroughly examine the dependence of localized solutions on a parameter of the model.     

Common Sections with Given Properties for a Finite Set of Convex Compacta

Let be convex compacta and let O be their common interior point. It is proved that there exists a 2-plane H through O such that for in–2 an affine image of a given centrally symmetric hexagon is inscribed in K_iH and has center at O. Furthermore, there exist n–3 2-planes H₁,...,H_n-3 through O lying at the same time in a 3-plane such that for in–3 an affine image of a regular octagon is inscribed in H_iK_i and has center at O. Bibliography: 9 titles.     

To the Theory of Quasi-Phase-Matched Parametric Amplification in Periodically Poled Optical Nonlinear Crystals

A theory of optical parametric amplification at high-frequency pumping in crystals with regular space modulation of the sign of the nonlinear coupling coefficient of interacting waves is developed. By applying the matrix method, the theory is based on a step-by-step approach. It is shown that, in the case where the pumping intensity is less than some critical value, the spatial dynamics of the signal intensity inside a separate layer with a constant nonlinear coefficient has an oscillatory behavior and the change of the signal intensity from layer to layer is defined, in general, by a polynomial dependence. The same law is valid for the change of variance of the signal's quadrature components. With a large number of layers, these dependences can be reduced to the well-known ones for homogeneous nonlinear optical crystals.     

Synthesis,crystal and molecular structure of 3,7-ditosyl-1,5-diphenyl-3,7-diazabicyclo[3.3.1]nonane

3,7-Ditosyl-1,5-diphenyl-3,7-diazabicyclo[3.3.1]nonane has been found to adopt a chair–chair conformation in the crystalline state in contrast to 3,7-ditosyl-1,5-diphenyl-3,7-diazabicyclo[3.3.1]nonan-9-one, which had been previously found to exist in a chair-boat conformation.     

Some exact solutions of the equations of the mechanics of nonhomogeneous media

We consider problems of the torsion of nonhomogeneous prismatic rods and the oscillation of plats of variable thickness operating in shear. We obtain an inequality characterizing the dependence of the maximum tangential stress on the shear modulus. An estimate from below is obtained for the torsional moment. An optimization problem for plates of variable thickness for a specified class of thicknesses is reduced to a problem on characteristic values for the Helmholtz equation.Translated from Matematicheskie Metody i Fiziko-Mekhanicheskie Polya, No. 25, pp. 87–90, 1987.     

Eigen electromagnetic oscillations in the waveguide-dielectric resonator with two-layer filling

The method of the solution problem on the eigen oscillations spectrum of electromagnetic field in the waveguide-dielectric resonator with the two-layer dielectric element was presented. The numerical calculations of the resonance frequencies for theHE ₁₁₁-,E ₀₁₁- andH ₀₁₁-oscillations types in the investigated structure were performed. The calculation results were correlated with experimental data.