It is established that, when determining the relationship between the contributions from the various possible mechanisms of suppression of birth of $J/\Psi$ charmonium in collisions of heavy ions, it is necessary to consider, along with the $J/\Psi$ dissociatiqn in the quark-gluon plasma, the competitive recombination process $3g \to J/\Psi$ of the three-gluon annihilation.
Show AbstractA new approach is suggested to least-squares treatment of the problem of reproducing functional dependences from measurement data with errors in the values of the function and its argument.
Show AbstractA system of equations is derived for Bogolyubov statistical particle operators on connected clusters that makes it possible to construct a unified perturbation theory for the homogeneous and the ordered phases irrespective of the type of symmetry of a many-particle system.
Show AbstractExact homogeneous isotropic open cosmological solutions to the Einstein equations of the six-dimensional Kaluza-Klein theory are found. Their analysis is presented and a comparison with analogous cosmological solutions in the five-imensional Kaluza-Klein model and the four-dimensional Fridman model is carried out.
Show AbstractThe focusing effect of ionospheric plasma waves on the probabilistic properties of the short-wave signal envelope is studied. It is shown that if only one envelope time realization is available, effective statistical characteristics should be used. Effective differential and integral probability distributions for the Rayleigh-Rice laws are obtained and analyzed. The role of effective statistical distribution moments is studied in a specific problem. The main conclusion made in the study is that the focusing effect is very important in processing fast fluctuations of the short-wave signal envelope, with standard probability distributions undergoing considerable distortions.
Show AbstractThe spectral and luminescence properties of acridine yellow and acridine orange in polyvinyl alcohol matrices were studied. The concentration dependences of the relative quantum yield of fluorescence show that in the systems studied the dye molecules form dimers and more complex associates. The quantwn yield of fluorescence from acridine yellow dimers is higher than that from monomers. The quantum yields and fluorescence decay times of various acridine molecular forms were determined, and the patterns of excitation energy transfer between these forms were studied. The critical radii of nonradiative energy transfer were calculated. The kinetic data show that excited monomeric acridines undergo rotational relaxation while excited associates do not.
Show AbstractConcentration dependences of the spectral and energy parameters of the lasing action by aqueous and ethanol solutions of Rhodamine 6G were studied. It was found that aqueous solutions of this dye generate two-band radiation.
Show AbstractLuminescence spectra of $Ce^{3+}$ in $Ca_{1-x}Sr_xS$ ($0 < x <1$) have been measured following excitations in the activator's band and at the fundamental absorption edge. It is shown that the model of a crystal field of cubic symmetry can be used to explain, in general, the spectrum evolution with changing concentration upon activator's excitation (with the exception of $x$ = 0.05 and 0.9), but this model cannot account for the peculiarities of the spectra arising upon excitation at the fundamental absorption edge. It is suggested that with band-to-band excitation a radiation-induced distortion of part of cerium luminescence centers occurs. A step-like variation of the luminescence parameters was detected as $x$ changed from 0 to 1, which seems to indicate that solid solutions are locally inhomogeneous.
Show AbstractThe mechanisms of the effect of natural illuminance on the initial $(\Phi^0)$ and maximum $(\Phi^{max})$ quantum yields of phytoplankton fluorescence and the efficiency of the initial stages of photosynthesis were studied. Remote measurements of $\Phi^0$ and $\Phi^{max}$ in phytoplankton samples were performed using the double-beam laser method. It was found that the principal mechanisms of control of the fluorescence yield by the light are the "energy-dependent" fluorescence quenching that occurs at illuminances about 5-20 klx and the photoinhibition of the initial stages of photosynthesis at illuminances of 30-100 klx.
Show AbstractThe influence of small losses in layers of thin-layer interference filters (containing two layers of the same thickness in the period) on their optical parameters was analyzed. Analytical expressions were obtained that help determine possible refractive indices of the medium to be matched and the wavelengths of matching as dependent on the losses. With a large number of periods of the filters, these parameters were shown to be independent of the number of periods and be determined only by the magnitude of specific losses.
Show AbstractThe theory of Raman laser is extended to the case of strong nonmonochromatic fields when the width of the pumping frequency spectrum is arbitrary and a transition saturation becomes possible. The resonator is assumed to include a selective element that narrows the spectrum of the generated Stokes wave. The conditions are determined at which the lasing efficiency may be made close to 100%.
Show AbstractApproximate dynamic equations for light wave power have been derived which describe the process of stimulated Raman backscattering with allowance for the inertia of molecular vibrations and the focusing of the pumping beam. The numerical calculation results agree well with experimental data on stimulated Raman scattering in hydrogen.
Show AbstractThe transverse Lorentz magnetoresistance of a one-zone model of a disordered crystalline alloy has been calculated within the framework of the coherent-potential approximation for the case of arbitrary scattering intensity. When the scattering is strong and the law of dispersion is isotropic, the magnetoresistance is proportional to the damping of the electronic states at the Fermi level.
Show AbstractA new method for estimating spin relaxation times in magnetic materials by ultrasound damping is considered. A description is given of a phenomenological theory of the relaxation mechanism of sound damping in a single-domain perfect crystal with consideration for a nonhomogeneous internal field. Numerical estimates of spin relaxation times in a Mn-Zn spinel single crystal are presented that use data on damping of a 30-MHz transverse wave. A possibility of separating the spin-spin and the spin-lattice relaxaton times is discussed.
Show AbstractThe polarization parameters of stationary states of the field in a nonlinear medium have been studied. These parameters are found to change only slightly when deviations of the refractive index of the mirror from unity are small.
Show Abstract
