Stress concentration in a spherical shell with two neighboring circular holes

We have solved analytically the problem of the stressed state in an isotropic shallow spherical shell with two circular holes. The cases of the close location of holes of both equal and unequal radii in the shell under the action of internal pressure have been investigated numerically. We have detected a considerable increase in stresses on the bulkhead between the holes at their approach.     

Formation mechanisms and structure of the luminescence spectra of a dense resonant medium

The purely thermal visible and infrared radiation emitted by a dense resonant medium (sodium vapor) heated nonuniformly to temperatures of 600–1200 K was investigated experimentally for the first time under conditions where the photon mean free path is comparable with the emission wavelength. The profile of the recorded spectra and the absolute luminescence intensities in the different spectral ranges show good agreement with the results of a numerical simulation using a previously developed theory of resonance radiation transport which assumes a Boltzmann spectral distribution of the resonant level population proportional to exp(−ℏω/T). The self-reversed resonant sodium line exhibited strong asymmetry and it was shown that under certain conditions, the luminescence spectrum of the medium may exhibit an additional broad peak on the far “red” limb of the resonance line. Calculations and measurements demonstrated that the intensity of the thermal emission of sodium vapor at this red peak is several orders of magnitude higher than that obtained from the standard theory of resonance radiation transport. This effect is arbitrarily termed an infrared “ catastrophe.” It is noted that in a solar corona plasma and in gas-discharge lamps, the far red limbs of the resonant lines may make a substantial contribution to the total luminescence intensity and in some cases, considerably exceed the intensity of the photorecombination and bremsstrahlung continuum. Zh. éksp. Teor. Fiz. 114, 135–154 (July 1998)     

Multiloop calculations inp-adic string theory and Bruhat-Tits trees

We treat the openp-adic string world sheet as a coset spaceF=T/, whereT is the Bruhat-Tits tree for thep-adic linear groupGL(2, _p ) and PGL(2, _p ) is some Schottky group. The boundary of this world sheet corresponds to ap-adic Mumford curve of finite genus. The string dynamics is governed by the local gaussian action on the coset spaceF. The tachyon amplitudes expressed in terms ofp-adic -functions are proposed for the Mumford curve of arbitrary genus. We compare them with the corresponding usual archimedean amplitudes. The sum over moduli space of the algebraic curves is conjectured to be expressed in the arithmetic surface terms. We also give the necessary mathematical background including the Mumford approach top-adic algebraic curves. The connection of the problem of closedp-adic strings with the considered topics is discussed.     

Determination of the secondary structures of proteins by circular dichroism spectra. Calculation of the protein basic circular dichroism spectra for antiparallel and parallel β-structures and β-bends

New “reference” circular dichroism spectra of α helix, β-structure (both parallel and antiparallel), β-bends, and the unordered form are obtained from circular dichroism spectra and x-ray data for six proteins (myoglobin, lysozyme, lactate dehydrogenase, papain, ribonuclease, and subtilisin BPN′). Circular dichroism spectra for α-helix and antiparallel β-structure are similar to those for poly(Llysine). The circular dichroism spectrum of the parallel β-structure is qualitatively similar to that theoretically calculated by Madison and Schellman. The circular dichroism spectrum of β-bends is qualitatively similar to that theoretically calculated by Woody. The spectrum of the unordered form is close to that of the denaturated proteins. These “reference” circular dichroism spectra used for the analysis of the secondary structure of ten globular proteins (besides the six reference proteins D-glyceraldehyde 3-phosphate dehydrogenase, concanavalin A, cytochrome c, and insulin).     

Calculation of stability of laminated composite coatings in tribotechnics

The stability of laminated coatings in tribotechnics under compression loads is investigated on the basis of the three-dimensional linearized theory of stability within the framework of a model of piecewise-homogeneous medium. The general formulation of the problem is given, and the solution of a particular example is considered. Translated from Mekhanika Kompozitnykh Materialov, Vol. 36, No. 2, pp. 229–236, 2000.