Showing papers by "Russian Academy of Sciences published in 1989"
TL;DR: The greater the distraction frequency, the better the outcome, and osteogenesis within the distraction gap of an elongating bone is unique, providing numerous applications in clinical traumatology, orthopedics, and other medical disciplines.
Abstract: To assess the influence of both the rate and the frequency of distraction on osteogenesis during limb elongation, a canine tibia was used with various combinations of distraction rates (0.5 mm, 1.0 mm, or 2.0 mm per day) and distraction frequencies (one step per day, four steps per day, 60 steps per day). The distractions were performed after both open osteotomy and closed osteoclasis. Histomorphic and biochemical studies were conducted on the elongated osseous tissue, fascia, skeletal muscle, smooth muscle, blood vessels, nerves, and skin. It was determined that distraction at a rate of 0.5 mm per day often led to premature consolidation of the lengthening bone, while a distraction rate of 2.0 mm per day often resulted in undesirable changes within elongating tissues. A distraction rate of 1.0 mm per day led to the best results. It was also observed that the greater the distraction frequency, the better the outcome. With optimum preservation of periosseous tissues, bone marrow, and blood supply at the time of osteotomy, stability of external fixation, and 1.0 mm per day of distraction in four steps, osteogenesis within the distraction gap of an elongating bone takes place by the formation of a physislike structure, in which new bone forms in parallel columns extending in both directions from a central growth zone. The growth plate that forms under the influence of tension-stress has features of both physeal and intramembranous ossification, yet is neither; instead, the distraction regenerated bone is unique, providing numerous applications in clinical traumatology, orthopedics, and other medical disciplines.
1,690 citations
TL;DR: A detailed survey of perturbation theory for nearly integrable systems, based upon the inverse scattering transform, and a minute account of results obtained by means of that technique and alternative methods are given in this paper.
Abstract: A detailed survey of the technique of perturbation theory for nearly integrable systems, based upon the inverse scattering transform, and a minute account of results obtained by means of that technique and alternative methods are given. Attention is focused on four classical nonlinear equations: the Korteweg-de Vries, nonlinear Schr\"odinger, sine-Gordon, and Landau-Lifshitz equations perturbed by various Hamiltonian and/or dissipative terms; a comprehensive list of physical applications of these perturbed equations is compiled. Systems of weakly coupled equations, which become exactly integrable when decoupled, are also considered in detail. Adiabatic and radiative effects in dynamics of one and several solitons (both simple and compound) are analyzed. Generalizations of the perturbation theory to quasi-one-dimensional and quantum (semiclassical) solitons, as well as to nonsoliton nonlinear wave packets, are also considered.
1,286 citations
TL;DR: In this paper, the authors show that the density distribution arising at the nonlinear stage of gravitational instability is similar to intermittency phenomena in acoustic turbulence, and that late nonlinear stages of density perturbation growth can be described by the Burgers equation, which is well known in the theory of turbulence.
Abstract: The density distribution arising at the nonlinear stage of gravitational instability is similar to intermittency phenomena in acoustic turbulence. Initially small-amplitude density fluctuations of Gaussian type transform into thin dense pancakes, filaments, and compact clumps of matter. It is perhaps surprising that the motion of self-gravitating matter in the expanding universe is like that of noninteracting matter moving by inertia. A similar process is the distribution of light reflected or refracted from rippled water. The similarity of gravitational instability to acoustic turbulence is highlighted by the fact that late nonlinear stages of density perturbation growth can be described by the Burgers equation, which is well known in the theory of turbulence. The phenomena discussed in this article are closely related to the problem of the formation of large-scale structure of the universe, which is also discussed.
780 citations
TL;DR: In this article, the Dubinin-Stoeckli equation for micropores of carbon adsorbents of the most probable slit-like, limited-size type lie the dispersion interactions between the adsorbate and adsorbent atoms as well as between the atoms of the adsorbed substance themselves.
601 citations
United States Geological Survey1, Stanford University2, Geological Survey of Canada3, University of São Paulo4, Massachusetts Institute of Technology5, British Geological Survey6, Karlsruhe Institute of Technology7, Cochin University of Science and Technology8, Russian Academy of Sciences9, Columbia University10, University of Paris-Sud11, University of South Carolina12, Luleå University of Technology13, National Autonomous University of Mexico14, Complutense University of Madrid15
TL;DR: In this article, the authors used regional patterns of present-day tectonic stress to evaluate the forces acting on the lithosphere and to investigate intraplate seismicity, and found that most intraplate regions are characterized by a compressional stress regime; extension is limited almost entirely to thermally uplifted regions.
Abstract: Regional patterns of present-day tectonic stress can be used to evaluate the forces acting on the lithosphere and to investigate intraplate seismicity. Most intraplate regions are characterized by a compressional stress regime; extension is limited almost entirely to thermally uplifted regions. In several plates the maximum horizontal stress is subparallel to the direction of absolute plate motion, suggesting that the forces driving the plates also dominate the stress distribution in the plate interior.
587 citations
University of Arizona1, California Institute of Technology2, New Mexico State University3, Russian Academy of Sciences4, Jet Propulsion Laboratory5, NASA Headquarters6, Cornell University7, Ames Research Center8, RAND Corporation9, University of Toronto10, Logica11, University of Wisconsin-Madison12, State University of New York System13, Stanford University14, University of Hawaii15
TL;DR: New Voyager 2 images of Neptune reveal a windy planet characterized by bright clouds of methane ice suspended in an exceptionally clear atmosphere above a lower deck of hydrogen sulfide or ammonia ices, dominated by a large anticyclonic storm system that has been named the Great Dark Spot.
Abstract: Voyager 2 images of Neptune reveal a windy planet characterized by bright clouds of methane ice suspended in an exceptionally clear atmosphere above a lower deck of hydrogen sulfide or ammonia ices. Neptune's atmosphere is dominated by a large anticyclonic storm system that has been named the Great Dark Spot (GDS). About the same size as Earth in extent, the GDS bears both many similarities and some differences to the Great Red Spot of Jupiter. Neptune's zonal wind profile is remarkably similar to that of Uranus. Neptune has three major rings at radii of 42,000, 53,000, and 63,000 kilometers. The outer ring contains three higher density arc-like segments that were apparently responsible for most of the ground-based occultation events observed during the current decade. Like the rings of Uranus, the Neptune rings are composed of very dark material; unlike that of Uranus, the Neptune system is very dusty. Six new regular satellites were found, with dark surfaces and radii ranging from 200 to 25 kilometers. All lie inside the orbit of Triton and the inner four are located within the ring system. Triton is seen to be a differentiated body, with a radius of 1350 kilometers and a density of 2.1 grams per cubic centimeter; it exhibits clear evidence of early episodes of surface melting. A now rigid crust of what is probably water ice is overlain with a brilliant coating of nitrogen frost, slightly darkened and reddened with organic polymer material. Streaks of organic polymer suggest seasonal winds strong enough to move particles of micrometer size or larger, once they become airborne. At least two active plumes were seen, carrying dark material 8 kilometers above the surface before being transported downstream by high level winds. The plumes may be driven by solar heating and the subsequent violent vaporization of subsurface nitrogen.
587 citations
TL;DR: It was found that cellular uptake of oligodeoxynucleotide derivatives is achieved by an endocytosis mechanism, which suggests the involvement of specific receptor proteins in binding of oligomers to mammalian cells.
Abstract: We have investigated the interaction of oligonucleotides and their alkylating derivatives with mammalian cells. In experiments with L929 mouse fibroblast and Krebs 2 ascites carcinoma cells, it was found that cellular uptake of oligodeoxynucleotide derivatives is achieved by an endocytosis mechanism. Uptake is considerably more efficient at low oligomer concentration (less than 1 microM), because at this concentration a significant percentage of the total oligomer pool is absorbed on the cell surface and internalized by a more efficient absorptive endocytosis process. Two modified proteins were detected in mouse fibroblasts that were treated with the alkylating oligonucleotide derivatives. The binding of the oligomers to the proteins is inhibited by other oligodeoxynucleotides, single- and double-stranded DNA, and RNA. The polyanions heparin and chondroitin sulfates A and B do not inhibit binding. These observations suggest the involvement of specific receptor proteins in binding of oligomers to mammalian cells.
519 citations
TL;DR: The available biochemical evidence is compatible with the proposal that viral proteins in which the NTP-binding pattern is evolutionarily conserved might all be NTPases involved in: i) duplex unwinding during DNA and RNA replication, transcription, recombination and repair, and possibly mRNA translation; ii) DNA packaging, and iii) dNTP generation.
Abstract: A compilation is presented of viral proteins containing the NTP-binding sequence pattern, and criteria are suggested for assessment of the functional significance of the occurrence of this pattern in protein sequences. It is shown that the distribution of NTP-binding pattern-containing proteins through the viral kingdom is strongly non-random. Sequence comparisons led to delineation of several families of these proteins, some of which could be brought together into superfamilies including also cellular proteins. The available biochemical evidence is compatible with the proposal that viral proteins in which the NTP-binding pattern is evolutionarily conserved might all be NTPases involved in: i) duplex unwinding during DNA and RNA replication, transcription, recombination and repair, and possibly mRNA translation; ii) DNA packaging, and iii) dNTP generation.
436 citations
TL;DR: In this article, the long-term free evolution of wave packets formed by highly excited states of quantum systems performing regular periodic motion in the classical limit is considered, and the universal asymptotic scenario of the wave function temporal development is discovered which provides the generation of a certain sequence of initial wave packet fractional revivals.
412 citations
TL;DR: A special light-sensitive chemical system, a variant of the Belousov–Zhabotinskii medium, in which chemical reaction fronts ('chemical waves') can be modified by light to demonstrate contrast modification, discerning of contours, and smoothing of partially degraded pictures.
Abstract: Image processing is usually concerned with the computer manipulation and analysis of pictures1. Typical procedures in computer image-processing are concerned with improvement of degraded (low-contrast or noisy) pictures, restoration and reconstruction, segmenting of pictures into parts and pattern recognition of properties of the pre-processed pictures. To solve these problems, digitized pictures are processed by local operations in a sequential manner. Here we describe a special light-sensitive chemical system, a variant of the Belousov–Zhabotinskii medium, in which chemical reaction fronts ('chemical waves') can be modified by light. Projection of a half-tone image on such a medium initiates a very complex response. We are able to demonstrate contrast modification (contrast enhancement or contrast decrease up to contrast reversal from positive to negative and vice versa), discerning of contours (for example, segmenting of pictures up to the extreme case of skeletonizing) and smoothing of partially degraded pictures.
392 citations
TL;DR: In this paper, in situ ultrahigh vacuum reflection electron microscopy has been applied to the study of the clean Si(111) stepped surface during sublimation under heating by electric current through the crystal.
TL;DR: An analytical reflectance model for a statistically homogeneous plant canopy has been developed in this article, considering both the single and the multiple scattering of radiation in the canopy and on the soil and accounting for the specular reflection of radiation on leaves and canopy hot spot.
TL;DR: The entropy and the free energy associated with these degrees of freedom can be calculated with high precision for simple molecules in the gas phase under certain conditions to larger molecules and to proteins.
Abstract: Molecules in solution have degrees of freedom representing overall movements of translation and rotation, internal vibrations and rotations about single bonds. The entropy and the free energy associated with these degrees of freedom can be calculated with high precision for simple molecules in the gas phase. The calculation can be extended under certain conditions to larger molecules and to proteins
TL;DR: It is shown that the partialHeat capacity of denatured protein significantly exceeds the heat capacity of native protein, especially in the case of globular proteins, and is close to the value calculated for an extended polypeptide chain from the known heat capacities of individual amino acid residues.
TL;DR: Investigation of disruption of tight packing of side chains in protein core shows that this disruption is an “all‐or‐none” transition (independent of how compact is the denatured state of a protein and independent of the protein–solvent interactions) because expansion of a globule must exceed some threshold to release rotational isomerization of side Chains.
Abstract: A theory of equilibrium denaturation of proteins is suggested. According to this theory, a cornerstone of protein denaturation is disruption of tight packing of side chains in protein core. Investigation of this disruption is the object of this paper. It is shown that this disruption is an "all-or-none" transition (independent of how compact is the denatured state of a protein and independent of the protein-solvent interactions) because expansion of a globule must exceed some threshold to release rotational isomerization of side chains. Smaller expansion cannot produce entropy compensation of nonbonded energy loss; this is the origin of a free-energy barrier (transition state) between the native and denatured states. The density of the transition state is so high that the solvent cannot penetrate into protein in this state. The results obtained in this paper make it possible to present in the following paper a general phase diagram of protein molecule in solution.
TL;DR: It is shown that there exists a threshold value of chain heterogeneity which separates two qualitatively different types of behavior and the relation of these results to thermodynamic aspects of protein folding is discussed.
TL;DR: The key research problems of micellar enzymology and its relation to enzyme membranology are discussed.
TL;DR: In this paper, the authors presented a complete noble gas study of mid-oceanic ridge basalt glasses (MORB) from a small ridge segment, centered on an along-strike topographic elevation of the Mid-Atlantic Ridge at about 14°N.
TL;DR: In this article, it was established that various critical regimes may occur for a model of two-dimensional pure quantum gravity, where effective fields with scaling dimensions Δk=−γstr·k/2, k=1, 2, 3, 4... are the critical exponent of string susceptibility.
Abstract: It is established that various critical regimes may occur for a model of two-dimensional pure quantum gravity. These regimes correspond to the presence of effective fields with scaling dimensions Δk=−γstr·k/2, k=1, 2, 3 ..., where γstr=−1/m, m=2, 3, 4 ... is the critical exponent of “string susceptibility” (with respect to the cosmological constant). This behaviour is typical for unitary conformal fields with the central charge c=1−6/m(m+1) in the presence of 2D-quantum gravity. We use the framework of loop equations for the invariant boundary functional, which are exactly solvable in this case.
01 Jan 1989
TL;DR: In this article, the authors present a SchoonschIP program for analytical computation of arbitrary massless, scalar, one-, two-and three-loop Feynman diagrams of the propagator type within dimensional regularization.
TL;DR: Fluorescence studies indicate that the inactivation results from reversible conformational changes (denaturation) of the enzymes, and a quantitative criterion is suggested for the selection of organic cosolvents to be used for enzymatic reactions in homogeneous water/organic solvent media.
Abstract: The dependence of the catalytic activities of α-chymotrypsin and laccase on the concentration of organic cosolvents (alcohols, glycols and formamides) in mixed aqueous media has a pronounced threshold character: it does not change up to a critical concentration of the non-aqueous cosolvents added, yet further increase of the latter (by only a small percentage, by vol.) leads to an abrupt decrease in enzyme activity. Fluorescence studies indicate that the inactivation results from reversible conformational changes (denaturation) of the enzymes. There is a linear correlation between the critical concentration of residual water (at which the enzyme inactivation occurs in a threshold manner) and the hydrophobicity of the organic cosolvents added. A quantitative criterion is suggested for the selection of organic cosolvents to be used for enzymatic reactions in homogeneous water/organic solvent media.
TL;DR: A review of the science of crystal growth can be found in this paper, particularly with regard to kinetics of growth and defects in crystal lattices, as well as a discussion of recent data.
Abstract: Growth of high quality crystals has played an important role in sophisticated, modern- day technologies and in recent advances in physics. It has also provided examples in the study of self-organizing dissipative structures. This paper reviews the science of crystal growth and discusses recent data, particularly with regard to kinetics of growth and defects in crystal lattices.
TL;DR: In this paper, the apparent volumes of 14 amino acids in aqueous solutions at a concentration of 3 mg/ml were measured densitometrically within the temperature range 15-55° C. The accuracy of measurements was ± 0.3%.
TL;DR: In this article, it was shown that twistor variables can be incorporated into the Lagrangian of a massless relativistic particle together with the local supersymmetrization of its proper time leads to a lagrangian which is invariant under the space-time global supersymmetry.
Abstract: It is shown that an explicit incorporation of twistor variables into the lagrangian of a massless relativistic particle together with the local supersymmetrization of its proper time leads to a lagrangian which is invariant under the space-time global supersymmetry. The equivalence of the Siegel symmetry and the local proper-time supersymmetry with a complexified Grassmann parameter is established. The Siegel algebra is formed by an irreducible set of covariant constraints and is closed off-shell.
TL;DR: In this article, the electronic structure and geometry of alkoxy groups on the surface of zeolites with a high silica content were analyzed and the net positive charge of the alkyl fragments was found to be low and almost constant when passing from methoxyl to isopropoxyl substituents.
TL;DR: Giant cationic palladium clusters approximated as Pd561L60(OAc)180 (L = phen, bipy) and pd561phen60O60(PF6)60 were synthesized and characterized with high resolution TEM, SAXS, EXAFS, IR and magnetic susceptibility data as discussed by the authors.
TL;DR: By adiabatic amplification of a periodically modulated cw signal in an optical fiber, a train of approximately independent solitons can be generated at a high repetition rate (up to the terahertz range).
Abstract: By adiabatic amplification of a periodically modulated cw signal in an optical fiber, a train of approximately independent solitons can be generated at a high repetition rate (up to the terahertz range). These pulse trains can be produced with fibers having slowly varying dispersion as well.
TL;DR: The patch-clamp technique and fluorescence polarization analysis suggest that variations of the CHS content in the plasma membrane of smooth muscle cells affect the kinetic properties of Ca2+-dependent K+ channels presumably due to changes in plasma membrane fluidity.
Abstract: The patch-clamp technique and fluorescence polarization analysis were used to study the dependence of Ca2+-dependent K+ channel kinetics and membrane fluidity on cholesterol (CHS) levels in the plasma membranes of cultured smooth muscle rabbit aortic cells. Mevinolin (MEV), a potent inhibitor of endogenous CHS biosynthesis was used to deplete the CHS content. Elevation of CHS concentration in the membrane was achieved using a CHS-enriching medium. Treatment of smooth muscle cells with MEV led to a nearly twofold increase in the rotational diffusion coefficient of DPH (D) and to about a ninefold elevation of probability of the channels being open (Po). The addition of CHS to the cells membrane resulted in a nearly twofold decrease in D and about a twofold decrease in Po. Elementary conductance of the channels did not change under these conditions. These data suggest that variations of the CHS content in the plasma membrane of smooth muscle cells affect the kinetic properties of Ca2+-dependent K+ channels presumably due to changes in plasma membrane fluidity. Our results give a possible explanation for the reported variability of Ca2+-dependent K+ channels kinetics in different preparations.