The Evolution of High-Intensity Light Pulses in a Nonlinear Medium Taking into Account the Raman Effect

Optics and Spectroscopy - Detection systems with deferred registration of luminescence signals are promising for performing complex tasks of imaging of biological objects due to their simplicity...     

Exact Solutions to the Problem of Dynamics of a Liquid with a Free Surface between Two Approaching Vertical Walls

Doklady Physics - Exact solutions of the classical problem of a plane unsteady potential flow of an ideal incompressible fluid with a free boundary are presented. The fluid occupies a semi-infinite...     

Kinetics of CO Molecules Taking into Account Resonant VE Exchanges in a Nonequilibrium Nozzle Flow

The kinetics of CO molecules with excited electronic levels for a nonequilibrium flow in nozzles is studied. Three electronic energy levels are taken into account; the VV exchanges of the vibrational energy within each electronic energy level, VT transitions from the vibrational energy to the translational energy, and VE exchanges between the vibrational energy and the electronic terms occur in the system. The system of equations of vibrational level kinetics and gasdynamics, which is written in the zeroth approximation of the Chapman–Enskog method, is solved numerically. Special attention is paid to estimating the effect of the VE exchanges of the vibrational energy on the formation of nonequilibrium populations of the vibrational levels. It is shown that resonant VE transitions considerably affect the relaxation process and noticeably change the population of the upper vibrational levels even in the absence of recombination and dissociation processes; VE exchanges also affect the time dependence of the vibrational temperature.     

Self-Similarity in the Problem of Laminar Film Boiling on a Vertical Surface Submerged in a Large Volume of a Liquid

Technical Physics - Using the methods of self-similarity for a laminar free-convective film boiling on a vertical finite-length surface submerged into a large volume of an arbitrarily subcooled...     

Kinetic Equation for the Density Matrix of Atoms in the Field of a Broadband One-Photon Packet Taking into Account the Non-Wiener Dynamics

We have derived the quantum master kinetic equation for the density matrix of an atomic system in the field of a narrow-beam one-photon broadband packet in the conditions when the latter plays the role of a thermostat. This equation takes into account the Stark interaction of atoms with the broadband field of surroundings of the system, which are in the state with zero photon number density, as well as the interaction of broadband fields at the atomic system.     

Letter: The Force of Gravity from a Lagrangian Containing Inverse Powers of the Ricci Scalar

We determine the gravitational response to a diffuse source, in a locally de Sitter background, of a class of theories which modify the Einstein-Hilbert action by adding a term proportional to an inverse power of the Ricci scalar. We find a linearly growing force which is not phenomenologically acceptable.     

Covariant Description of the Interaction of an Electromagnetic Field with Hadrons, Taking into Account Spin Polarizabilities

The covariant Lagrangian of the interaction of an electromagnetic field with polarizable spin hadrons has been constructed invoking sequentially the principle of correspondence between relativistic electrodynamics of moving media and relativistic quantum field theory and taking into account the cross-symmetry condition. It has been shown that for 1/2-spin hadrons, to the third order in radiation frequency, the contribution to the effective Lagrangian is from the spin polarizabilities.     

Millimeter-Wave Spectrum of CF(2)Cl(2), Taking into Account the Hyperfine Structure

A new investigation of the CF(2)(35)Cl(2) ground state rotational spectrum in the 50-100 GHz frequency range gave an opportunity to improve the accuracy of rotational and quartic distortion parameters by an order of magnitude and to determine values of six sextic centrifugal distortion parameters. A special technique was used to process line profiles of unresolved or partially resolved hyperfine structures of rotational transitions. It allowed us to improve significantly values for the diagonal parameters of quadrupole coupling chi(aa), (chi(bb)-chi(cc)) and to determine the off-diagonal parameter chi(ab). Copyright 2000 Academic Press.     

Improvement of the Accuracy of Measuring the Spectral and Integral Characteristics of Photodiodes by Taking into Account Their Nonlinearity

We suggest a method for improving the accuracy of measurement of the spectral and integral characteristics of photodetectors (in particular, photodiodes with current-to-voltage converters) in the range of powers for which the nonlinearity parameter determined by the double-aperture method is independent of the irradiation power. We show that in this case it is possible to obtain analytical expressions for both the calibration characteristic of the indicated devices and the correction coefficients which minimize the systematic error in the measurements of the coefficients of transmission and reflection of specimens and also to analytically couple the integral and spectral parameters of nonlinearity.     

Some Remarks on a Nongeometrical Interpretation of Gravity and the Flatness Problem

In a nongeometrical interpretation of gravity,the metric g(x) = + (x)is interpreted as an effective metric, whereas(x) is interpreted as afundamental gravitational field, propagated in spacetime which isactually flat. Some advantages and disadvantages of suchan interpretation are discussed. The main advantage isa natural resolution of the flatness problem.     

Simulation of Fission Product Release from Microfuel Particles Taking into Account the Effects of Trapped Fraction and Concentration Jumps at the Interfaces

A modification of the FP Kinetics code [1] has been performed to calculate the fission product release from HTGR microfuel particles, allowing for chemical binding, limited solubility effects, and component concentration jumps at the interfaces of the coating layers. A comparison is made of the release curves of Cs from microfuel particles calculated using the FP Kinetics and PARFUME codes [2]. It is shown that taking into account the concentration jumps at the interfaces of the silicon carbide layer makes it possible to give a noncontradictory explanation of the experimental data obtained for Cs release in post-reactor thermal testing. The need for performing experiments to determine the limits of solubility in coating materials is noted.