Crystal structure of C17H20FN3O 32+ ·CuBr 42? ·H2O

A new compound C₁₇H₂₀FN₃O₃²⁺·CuBr₄²⁻·H₂O is synthesized in the crystal form, where C₁₇H₁₈FN₃O₃ (CfH, ciprofloxacin) is 4-oxo-7-(1-piperazinyl)-6-fluoro-1-cyclopropyl-1,4-dihydroquinoline-3-carboxylic acid. Crystallographic data of ciprofloxacinium tetrabromocuprate(II) monohydrate, C₁₇H₂₂Br₄CuFN₃O₄: a = 8.214(1) ?, b = 10.781(2) ?, c = 13.703(2) ?, α = 85.144(2)°, β = 79.119(2)°, γ = 84.018(2)°, V = 1182.5(4) ?³, P [`1]\bar 1 space group, Z = 2. Supramolecular architecture of the crystal differs from that established for C₁₇H₂₀FN₃O₃²⁺·CuCl₄²⁻·H₂O by the absence of π-π interactions of the aromatic rings of CfH₃²⁺ ions and also the structural motifs formed by intermolecular hydrogen bonds.     

High-intensity femtosecond laser systems based on coherent combining of optical fields

The basic design principles of high-intensity laser systems based on coherent combining of radiation of multichannel laser facilities are considered. The influence of the instability of parameters of individual beams on coherent combining efficiency is analyzed, and requirements on their values for realization of high-efficiency coherent combining are determined. The fundamental possibility of coherent combining of parametrically amplified femtosecond pulses is experimentally demonstrated for the first time. Combining pulses with an energy of ～1 mJ (pulse duration of 25–30 fs) with an efficiency exceeding 83% is realized by using a spherical mirror and a specially developed high-precision electro-optical relative time jitter stabilization scheme, which ensures its stability at ～170 as level. The analysis conducted and the experimental data confirm that there are no fundamental limitations on intensity scaling of the high-intensity laser system based on coherent combining being developed at the Institute of Laser Physics of the Siberian Branch of the Russian Academy of Sciences.     

Studying liquid-crystal systems with impurities using matrix-formalism methods

We use the matrix formalism to investigate a liquid-crystal system containing impurities. As an example, we calculate correlation functions for fluctuations of the director orientation and of the order parameter, which characterizes an isotropic subsystem. __________ Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 147, No. 2, pp. 323–327, May, 2006.     

Future of low-x forward physics at RHIC

Comparisons of particle production from high-energy ion collisions with next-to-leading order perturbative QCD calculations show good agreement down to moderate transverse momentum values. Distributions of azimuthal angle differences between coincident hadrons in these collisions support a partonic origin to the particle production, again down to moderate transverse momentum values. The rapidity dependence of inclusive and coincident particle production can therefore be used to probe parton distribution functions down to small momentum fractions where theory anticipates that parton saturation could be present. This paper describes how such experiments could be completed.Arrival of the final proofs: 27 July 2005PACS: 12.38 Qk, 13.88. + e, 24.85. + p     

Hamiltonian formalism,quantization and S matrix for supergravity

The canonical formalism for supergravity is constructed. The algebra of canonical constraints is found. The correct expression for the S matrix is obtained. Usual “covariant methods” lead to an incorrect S matrix in supergravity, since a new four-particle interaction of ghostfields survives in the Lagrangian expression of the S matrix.     

Frustrated exchange interactions formation at low temperatures and high hydrostatic pressures in La<Subscript>0.70</Subscript>Sr<Subscript>0.30</Subscript>Mn<Subscript>O2.85</Subscript>

The magnetic and thermal properties of the anion-deficient La_0.70Sr_0.30MnO_2.85 manganite are investigated in wide temperature (4–350 K) range, including under hydrostatic pressure (0–1.1 GPa). Throughout the pressure range investigated, the sample is spin glass with diffused phase transition into paramagnetic state. It is established, that spin glass state is a consequence of exchange interaction frustration of the ferromagnetic clusters embeded into antiferromagnetic clusters. The magnetic moment freezing temperature T _f of ferromagnetic clusters increases under pressure, freezing temperature dependence on pressure is characterized by derivative value ∼4.5 K/GPa, while the magnetic ordering T _MO temperature dependence is characterized by derivative value ∼13 K/GPa. The volume fraction of sample having ferromagnetic state is V _fer ∼ 13% and it increases under a pressure of 1.1 GPa by ΔV _fer ≈ 6%. Intensification of ferromagnetic properties of the anion-deficient La_0.70Sr_0.30MnO_2.85 manganite under hydrostatic pressure is a consequence of oxygen vacancies redistribution and unit cell parameters decrease. The most likely mechanism of frustrated exchange interactions formation is discussed.     

Truncated Estimation of Ratio Statistics with Application to Heavy Tail Distributions

The problem of estimation of the heavy tail index is revisited from the point of view of truncated estimation. A class of novel estimators is introduced having guaranteed accuracy based on a sample of fixed size. The performance of these estimators is quantified both theoretically and in simulations over a host of relevant examples. It is also shown that in several cases the proposed estimators attain — within a logarithmic factor — the optimal parametric rate of convergence. The property of uniform asymptotic normality of the proposed estimators is established.     

Behaviour of Nematic Liquid Crystals in Inhomogeneous Electric Fields

The behaviour of homogeneously aligned nematic liquid crystal layers in inhomogeneous electric fields has been theoretically and experimentally investigated. The variation of the phase retardation of monochromatic light along nematic liquid crystal layer at the edges of a cell electrode has been obtained. Anisotropic character of the resolution of liquid crystal devices is shown.     

Pressure-induced transformation of metals into dense plasma

Abstract

The pressure-induced transformation of metals into dense plasma is considered. It is shown, that the change in dependence of resistance from external pressure allows one to find out this transition.     

Optical nutation in the exciton range of spectrum

Optical nutation in the exciton range of spectrum is studied in the mean field approximation taking into account exciton-photon and elastic exciton-exciton interactions. It is shown that the features of nutation development are determined by the initial exciton and photon densities, the resonance detuning, the nonlinearity parameter, and the initial phase difference. For nonzero initial exciton and photon concentrations, three regimes of temporal evolution of excitons and photons exist: periodic conversion of excitons to photons and vice versa, aperiodic conversion of photons to excitons, and the rest regime. In the rest regime, the initial exciton and photon densities are nonzero and do not change with time. The oscillation amplitudes and periods of particle densities determined by the system parameters are found. The exciton self-trapping and photon trapping appearing in the system at threshold values of the nonlinearity parameter were predicted. As this parameter increases, the oscillation amplitudes of the exciton and photon densities sharply change at the critical value of the nonlinearity parameter. These two phenomena are shown to be caused by the elastic exciton-exciton interaction, resulting in the dynamic concentration shift of the exciton level.