I. M. Gel'fand, M. I. Graev, Z. Ya. Shapiro
This paper formulates and solves an integral geometry problem for a pair of oriented real Grassmann manifolds, the spaces of l-dimensional and k-dimensional subspaces of Euclidean n-space, under the assumptions l < k, l + k ≤ n, and even k minus l. It defines a transform from homogeneous smooth func…
D. P. Shashkin, M. A. Simonov, N. V. Belov
The paper determines the crystal structure of the mineral calciborite and evaluates its chemical formula in light of earlier analytical and synthetic-polymorph data. Using Weissenberg X-ray diffraction intensities, Patterson methods, electron-density syntheses, and least-squares refinement in the or…
Yu. V. Matiyasevich
This paper proves that every enumerable predicate is Diophantine, thereby establishing the algorithmic unsolvability of Hilbert’s tenth problem for Diophantine equations. Building on results of Davis, Putnam, and Robinson, the argument reduces the problem to showing that a Diophantine predicate with…
I. I. Parovichenko
The paper studies the partially ordered set of equivalence classes of H-closed extensions of a Hausdorff space, ordered by admissible continuous maps. It proves that every nonempty family of such extensions has a supremum, using products of representative extensions, the diagonal copy of the origina…
V. E. Zakharov, R. Z. Sagdeev
This paper analyzes the spectrum of acoustic turbulence in a compressible potential flow represented as an ensemble of interacting sound waves. Using normal wave variables, resonance considerations, and dimensional Kolmogorov-type arguments, it estimates the nonlinear interaction cone and interactio…
A. J. Lovater
The paper studies boundary behavior of the derivative of a function analytic and univalent in the unit disk, focusing on radial and angular limiting values on the unit circle. Using Koebe distortion estimates, it first establishes that such derivatives are normal analytic functions, and then proves …
Yu. I. Kulakov
The paper formulates a mathematical principle intended to express the equivalence of physical objects with respect to a physical law, called phenomenological symmetry. It defines physical structures on two sets through analytic functional relations invariant under permutations of selected elements, …
G. Sh. Rubinshtein
The paper studies an intrinsic characterization of relatively open convex subsets of real vector spaces through abstract axial structures, formalizing order-theoretic notions of lines, segments, convexity, dimension, and parallelism. It introduces a Euclidean condition for generalized vector spaces …
EDWIN HEWITT, DUSA McDUFF
This note studies maximal two-sided ideals in the Banach algebra of regular complex Borel measures on a compact group, addressing whether every simple homomorphic image of this algebra must be finite-dimensional. The authors construct maximal ideals in products of finite-dimensional operator algebra…
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This note studies universal polynomial iterative processes for solving linear operator equations with self-adjoint positive definite operators in a Hilbert space, assuming the spectrum lies in a fixed interval. Using the spectral representation of the error and orthogonal polynomials with appropriat…
A. L. Rukhin
This note studies shift families on the real line for which the optimal homogeneous estimator is essentially independent of the chosen symmetric loss or quality criterion. It defines strongly symmetric densities through a zero set condition and shows that, under regularity assumptions, such laws are…
A. M. EZHOV, S. P. PUL'KIN
The paper studies a Tricomi boundary value problem for a class of mixed type equations with parameter \(\lambda\), aiming to obtain estimates without assuming smallness of the coefficient or of the transition interval. By introducing an exponential substitution based on a Riccati equation and applyi…
E. N. Treushnikov, V. V. Ilyukhin, N. V. Belov
The paper reports a single-crystal X-ray determination of the crystal structure of sodium zirconium oxyorthosilicate, Na2ZrSiO5, a compound of interest in alkali zirconia silica systems used for heat-resistant materials and adsorbents. Using Patterson and electron-density syntheses followed by least…
E. Ya. VILKOVISKIĬ
The paper examines whether impurity ions of higher charge in a plasma carrying a strong electric current can attain directed energies sufficient for nuclear synthesis with the principal ions. Using Gurevich’s two stationary states of impurity ion motion under Coulomb conductivity, it estimates react…
E. F. Afanas'ev, G. P. Cherepanov
This paper studies self-similar dynamic plane-strain elasticity problems for an infinite isotropic body containing a rectilinear crack that begins at a point source and expands at constant subsonic velocity. Using displacement potentials and the Smirnov-Sobolev transformation, the boundary condition…
Sh. A. Alimov
The paper studies Fourier expansions of functions in Besov classes with respect to an arbitrary complete orthonormal system of eigenfunctions of a nonnegative self-adjoint extension of the Laplace operator in a star-shaped domain. It establishes estimates for dyadic blocks of Fourier coefficients of…
M. G. Kuz'mina
The paper treats the Milne problem for linearly polarized radiation in a semi-infinite plane atmosphere with Rayleigh scattering, constant total flux, and no incident external radiation at the boundary. It formulates the transfer equation for two polarization components, derives moment equations and…
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This note studies the asymptotic order, in the number of nodes, of the degree of exactness of Chebyshev’s equal-weight quadrature formula for a nonnegative summable weight on a finite interval. Using methods associated with Bernstein and Akhiezer, it derives local estimates from the behavior of the …
V. V. Barkovskii
The paper studies mixed boundary value problems for partial differential equations in which part of the boundary carries nonstationary conditions, reducing them to Cauchy problems for evolution equations in orthogonal sums of Hilbert spaces. It constructs an operator generated by an elliptic boundar…
V. I. Arnautov
This paper addresses whether infinite rings, in particular countable rings, can be endowed with a Hausdorff nondiscrete topology compatible with ring operations. It proves a criterion for such a topologization with a prescribed open ideal, formulated in terms of avoiding roots of finitely many polyn…
K. I. Gringauz, V. A. Troitskaya, È. K. Solomatina, R. V. Shchepetnov
This paper examines how solar wind parameters relate to the periods of steady micropulsations in the Earth’s electromagnetic field. Measurements of solar wind ion flux from Venera 2, Venera 4, Venera 5, Venera 6, and IMP 1 are compared with simultaneous telluric current observations from several geo…
A. I. Veksler
The paper studies closed P-sets in bicompact topological spaces, focusing on their role in quasiextremal, or basically disconnected, bicompacts and in the theory of partially ordered vector lattices. It translates earlier results on extended K-sigma spaces into topological terms, showing that for a …
V. A. Chernetskii
This note studies the Carleman boundary value problem with orientation reversing shift on the boundary of a finite multiply connected domain. It constructs a special conformal welding function that maps the problem to a Riemann boundary value problem on a contour consisting of open arcs, using integ…
I. A. Kipriyanov
This paper studies Green functions for a class of singular elliptic differential operators in a half-space, involving a Bessel-type operator in the normal variable and weighted Sobolev spaces adapted to the boundary singularity. It establishes coercive estimates for a shifted operator, constructs th…
L. P. Vinnik
This paper examines the origin of longitudinal waves observed in 4 to 6 second microseisms recorded in a quiet intracontinental region. Using wave-number decomposition of microseismic fields from a station group near Ust-Kamenogorsk, the study estimates apparent velocities, azimuths, and source loca…
S. I. Vainshtein
This paper examines whether weak magnetic fields can grow in a medium with acoustic turbulence, using the small parameter provided by the short correlation time of acoustic fluctuations. Treating the velocity field statistically and applying perturbation theory to the magnetic induction equation, it…
N. V. Vershinskii
This paper reports measurements of humidity pulsations in the near-surface marine atmosphere during the 1969 Soviet-French expedition in the Mediterranean Sea. Using a low-inertia quartz adsorption humidity sensor connected to digital recording equipment, the study obtained energy spectra under seve…
O. P. Pecherskii, A. M. Sidoruk, V. D. Tarasov, V. A. Tsukerman
This paper describes the design and testing of a pulsed high-voltage generator using purified water as the dielectric for producing short, intense pulses of fast electrons and hard bremsstrahlung X-rays. The apparatus combines a Marx pulse circuit with a coaxial water-dielectric storage line, which …
J. M. Barzdiņš
This paper studies whether algorithmically unsolvable mass problems can nevertheless be solved correctly on almost all instances along infinitely many initial segments. For recursively enumerable sets, it proves that for every positive error bound there is a general recursive predicate agreeing with…
Yu. I. Domshlak
The paper studies oscillation of vector-valued solutions of second-order differential equations in finite-dimensional Euclidean and real Hilbert spaces, proposing a coordinate-invariant definition based on zeros of all scalar projections. For equations of the form u''(t) + F(t,u(t))u(t)/||u(t)|| = 0…
A. A. Viktorova, S. A. Zhevakin
The paper refines earlier calculations of the microwave and far-infrared rotational absorption spectrum of the water-vapor dimer, using a linear rigid dimer model with hindered internal rotation about the hydrogen bond. Replacing the harmonic approximation for the torsional barrier by a cosine poten…
L. Yu. Kharchenko, P. V. Klevtsov, T. M. Polyanskaya
The study reports the synthesis and characterization of rare-earth oxytungstate chlorides of composition Ln3WO6Cl3, where Ln is Ce, Pr, or Nd, extending a previously identified group of tungstate chlorides containing chlorine anions. Single crystals were obtained by hydrothermal crystallization in c…
V. P. Luferenko, G. D. Suvorov
The paper studies families of one-to-one mappings between metric spaces equipped with two metrics, motivated by distortion estimates in relative metrics for conformal, quasiconformal, and related mappings. It proves that a uniform two-sided distortion estimate in one metric is equivalent to equicont…
Ya. S. Derbenev, A. M. Kondratenko,
The paper develops a general treatment of spin motion for particles in storage rings or accelerators with arbitrary electromagnetic fields, assuming the existence of a closed equilibrium orbit. It gives a physically transparent derivation of the spin precession equation including Thomas rotation, th…
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This paper examines the resolving power of three-dimensional holograms recorded in volume photosensitive media, where the usual aperture-based treatment of planar holograms is insufficient. Using the kinematic theory of diffraction by three-dimensional periodic structures, the authors derive an inte…
I. S. Ovchinnikov
The paper studies the existence of homeomorphic plane mappings between simply connected domains that solve first order elliptic systems whose ellipticity may degenerate. It develops an approximation approach, replacing the degenerate system or the domain by nondegenerate ones and passing to a limit …
V. I. Voitov, O. V. Kopelevich
This paper analyzes angular light scattering indicatrices measured in transparent waters of the northern Indian Ocean to test whether differences among seawater scattering curves can be explained solely by varying proportions of molecular and suspended-particle scattering. Using 163 measurements, th…
V. V. Shuleikin
This paper develops an approximate heat-engine model relating tropical hurricane power to the temperature of the underlying ocean surface water. Using earlier algebraic relations for hurricane structure, condensation heat release, pressure differences, wind parameters, and frictional dissipation at …
V. V. Vitkevich, Yu. P. Shitov
Observations of the pulsar CP 0808 at 60 to 110 MHz with the Pushchino DKR-1000 radio telescope are analyzed to characterize its meter-wave radio emission and short-period subpulse behavior. The study finds that pulses consist of one to three subpulses separated on average by 53.6 ms, forming a clas…
Academician B. N. PETROV, V. A. BODNER, K. B. ALEKSEEV
This paper derives an analytical attitude control law for a spatial rotational maneuver of a flying vehicle, formulated as a single rotation about a prescribed axis rather than as three successive body-axis rotations. Using Euler equations, inertia transformations, and the principle of extensive con…
A. I. Veksler
The paper studies when a commutative associative ring without nonzero nilpotents and with torsion-free additive group can be equipped with partial orders compatible with multiplication, especially orders stronger than those of partially ordered rings of functions. It introduces u-cones and phi-cones…
I. M. Rapoport
The paper treats the three-dimensional equilibrium problem for an elastic body bounded by two parallel planes and subjected to arbitrary surface and body forces. It reduces the loading to components satisfying integral balance conditions, formulates auxiliary equations for polynomial displacement te…
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The paper studies the computation of saddle points for twice continuously differentiable functions that are strictly convex in one variable and strictly concave in the other, when both variables are constrained to bounded polyhedra. It characterizes saddle points by the vanishing of distances from t…
L. G. Khazin, F. Kh. Tselman
This paper studies nonlinear interaction in resonant conservative Hamiltonian systems with multiple degrees of freedom, assuming a single resonance relation among distinct linear frequencies. Using a polynomial canonical transformation, the authors reduce the Hamiltonian to a resonant normal form up…
M. F. Shirokov
The paper examines special noncovariant coordinate conditions in general relativity defined by setting selected components of gravitational energy, momentum pseudotensors to zero. It argues that, although such conditions appear nonlinear and unusual, they are satisfied by several exact solutions and…
V. N. Logvinenko, I. V. Ostrovskii, L. I. Ronkin
The paper studies entire functions of several complex variables that are real on real vectors and transform a vector of independent standard normal variables into a standard normal variable. It strengthens a result of Linnik and Eidlin by proving that any such function is either a normalized real li…
V. V. Kerzhanovich, B. N. Andreev, V. M. Gotlib
This paper analyzes atmospheric wind dynamics on Venus using Doppler measurements from the descent vehicles of the Venera 5 and Venera 6 automatic interplanetary stations. Radial velocity variations during parachute descent are processed after accounting for planetary motion, parachuting velocity, o…
T. V. Terekhova
The paper studies a continuous function of three variables, vanishing outside a ball, through three notions of variation defined by the structure, planar sections, and area of its level sets. It proves comparison estimates for partial variations over disjoint balls and a geometric lemma relating loc…
V. A. Kazinskii
This paper examines temporal variations in the second derivatives of the gravitational potential, focusing on curvature differences and gravity gradients as possible indicators of tectonic processes. Continuous variometric measurements were conducted in 1967 at the Obninsk Observatory and in 1968 in…
I. G. Fikhtengol'ts
This paper examines gravitational pressure in a conformally flat Friedmann-Lobachevsky space with metric tensor proportional to the Minkowski tensor. It derives expressions for the Christoffel symbols, curvature tensor, and Einstein equations in terms of the conformal factor, then specializes to a d…