Showing papers by "Moscow State University published in 1986"
TL;DR: In this article, a microscopic approach to the theory of small, current-biased tunnel junctions is developed, which yields a natural account of the secondary quantization of both the single-electron (quasiparticle) and Cooper-pair (Josephson) current components.
Abstract: A microscopic approach to the theory of small, current-biased tunnel junctions is developed. This approach yields a natural account of the “secondary” quantization of both the single-electron (quasiparticle) and Cooper-pair (Josephson) current components. The theory shows that the current of the single electrons is blocked by their Coulomb interaction at low temperatures within a considerable range of the junction voltage. As a result of the blockade, coherent oscillations of the voltage can arise even in the absence of Josephson coupling, e.g., for single-electron tunneling (SET) between normal metal electrodes. The most significant features of these “SET” oscillations and their coexistence with Bloch oscillations in Josephson junctions are studied in detail. Prospects of experimental verification of the predicted effects and of their possible applications are discussed.
836 citations
TL;DR: It is proposed that central regulation of stretch reflex thresholds governs voluntary control over muscle force and length and concluded that voluntary movements are effected by the central nervous system with the help of the mechanisms that underlie the variability and modifiability of innate motor patterns.
Abstract: The following factors underlying behavioral plasticity are discussed: (1) reflex adaptability and its role in the voluntary control of movement, (2) degrees of freedom and motor equivalence, and (3) the problem of the discrete organization of motor behavior. Our discussion concerns a variety of innate motor patterns, with emphasis on the wiping reflex in the frog.It is proposed that central regulation of stretch reflex thresholds governs voluntary control over muscle force and length. This suggestion is an integral part of the equilibrium-point hypothesis, two versions of which are compared.Kinematic analysis of the wiping reflex in the spinal frog has shown that each stimulated skin site is associated with a group of different but equally effective trajectories directed to the target site. Such phenomena reflect the principle of motor equivalence -the capacity of the neuronal structures responsible for movement to select one or another of a set of possible trajectories leading to the goal. Redundancy of degrees of freedom at the neuronal level as well as at the mechanical level of the body's joints makes motor equivalence possible. This sort of equivalence accommodates the overall flexibility of motor behavior.An integrated behavioral act or a single movement consists of dynamic components. We distinguish six components for the wiping reflex, each associated with a certain functional goal, specific body positions, and motor-equivalent movement patterns. The nervous system can combine the available components in various ways in forming integrated behavioral sequences. The significance of command neuronal organization is discussed with respect to (1) the combinatory strategy of the nervous system and (2) the relation between continuous and discrete forms of motor control. We conclude that voluntary movements are effected by the central nervous system with the help of the mechanisms that underlie the variability and modifiability of innate motor patterns.
429 citations
TL;DR: To purify this protein from bovine brain, the ability of kinesin to bind to taxol-stabilized microtubules in the presence of inorganic tripolyphosphate was used, which indicates that this molecule is most probably a complex of these polypeptides.
Abstract: Recently, a protein called kinesin was described, which is capable of inducing movement of inert particles along microtubules. To purify this protein from bovine brain, we used the ability of kinesin to bind to taxol-stabilized microtubules in the presence of inorganic tripolyphosphate. The brain kinesin preparation contained one major polypeptide of 135 kDa and four minor polypeptides of 45-70 kDa. The minor polypeptides were eluted from a gel-permeation chromatography column at the same position as the major component. All the polypeptides of the preparation were capable of binding to the microtubules under identical conditions. The kinesin molecule is most probably a complex of these polypeptides. Brain kinesin had a very low ATPase activity (0.06-0.08 mumol X min-1 X mg-1 in 3 mM Mg2+ at pH 6.7). ATPase activity was strongly stimulated by microtubules (Vmax = 4.6 mumol per min per mg of kinesin). Microtubule-activated kinesin ATPase had a Km for ATP between 10 and 12 X 10(-6) M and a Kapp for microtubules (i.e., polymerized tubulin concentration required for a half-maximal activation) of 12-14 X 10(-6) M. Kinesin had a significant ATPase activity even without microtubules if 2 mM Ca2+ was substituted for Mg2+ (Vmax = 1.6 mumol X min-1 X mg-1; Km = 800 X 10(-6) M). Kinesin is therefore a mechanochemical ATPase that is activated by microtubules.
199 citations
TL;DR: In this paper, the average step growth rate v = R/p has been determined as a function of relative supersaturation σ, demonstrating the unimportance of surface and bulk diffusion.
122 citations
TL;DR: The phase transitions are of displacive type and nearly of second order as mentioned in this paper. But the phase transitions were not of the second order in the case of KTiOPO4 with Curie points of 934, 789, and 581 °C.
Abstract: Crystals of KTiOPO4, RbTiOPO4, and TlTiOPO4 are grown, studied, and found to be ferroelectrics with Curie points of 934, 789, and 581 °C, respectively. The phase transitions are of displacive type and nearly of second order. These crystals have also a high ionic conductivity and can exhibit a strong low-frequency dielectric relaxation.
[Russian Text Ignored].
114 citations
TL;DR: A model of recombination between picornaviral RNA genomes has been proposed and the essence of this model consists in bringing together homologous regions of two recombining RNA genomes via formation of intermolecular duplexes.
113 citations
TL;DR: In this paper, a relativistic theory of gravitation (RTG) is constructed on the basis of the special relativity and geometrization principle, which leads to an exceptionally strong prediction: the universe is not closed but just flat.
Abstract: In the present paper a relativistic theory of gravitation (RTG) is unambiguously constructed on the basis of the special relativity and geometrization principle. In this a gravitational field is treated as the Faraday--Maxwell spin-2 and spin-0 physical field possessing energy and momentum. The source of a gravitational field is the total conserved energy-momentum tensor of matter and of a gravitational field in Minkowski space. In the RTG the conservation laws are strictly fulfilled for the energy-moment and for the angular momentum of matter and a gravitational field. The theory explains the whole available set of experiments on gravity. By virtue of the geometrization principle, the Riemannian space in our theory is of field origin, since it appears as an effective force space due to the action of a gravitational field on matter. The RTG leads to an exceptionally strong prediction: The universe is not closed but just ''flat.'' This suggests that in the universe a ''missing mass'' should exist in a form of matter.
104 citations
102 citations
TL;DR: In this paper, cross sections and charged multiplicity distributions for π+p, K+p andpp interactions at 250 GeV/c are presented and compared to each other as well as to earlier (for π +p and K +p lower energy) data.
Abstract: Cross sections and charged multiplicity distributions for π+p,K+p andpp interactions at 250 GeV/c are presented and compared to each other as well as to earlier (for π+p andK+p lower energy) data. Consistently, the meson-proton (M+p) data have narrower multiplicity distributions and higher average multiplicity thanpp data. Up to our energy, generalized KNO functions describe the energy dependence of the shape of the multiplity distribution with one parameter forM+p and one forpp collisions. If interpreted in terms of negative binomials, the parameter 1/k tends to be slightly lower forM+p than forpp data. For both types of hadron-hadron collision, 1/k is larger than fore+e− andlp collisions.
101 citations
TL;DR: In this paper, the three-body α + 2N model was generalized to describe the spectrum of the low-lying states of the A = 6 nuclei and the levels of the nuclei were shown to be differently sensitive to the various Nα interaction components.
97 citations
TL;DR: The TUNDE-M energetic particle instrument aboard the Vega 1 spacecraft detected intense fluxes of energetic (≥40 keV) ions in the vicinity of comet Halley, starting at a distance of 107 km from closest approach.
Abstract: The TUNDE-M energetic particle instrument aboard the Vega 1 spacecraft detected intense fluxes of energetic (≥40 keV) ions in the vicinity of comet Halley, starting at a distance of 107 km from closest approach. Three regions of differing ion characteristics have been identified. An outer region, several million kilometers in extent, contains pick-up ions in the solar wind. A second region, inside the bow shock (several hundred thousand kilometres in extent), contains the most intense fluxes, whereas the innermost region (several tens of thousands of kilometres) is characterized by lower intensities and sharp spikes near closest approach (∼8,900 km from the nucleus).
TL;DR: In this paper, a mathematical model of nonstationary melting processes of ice including particles of morainic material is presented, where the problem is treated as a Stephen-type one with the phase boundary of ice melting being located under the debris cover.
Abstract: A mathematical model is presented of non-stationary melting processes of ice including particles of morainic material. The problem is treated as a Stephen-type one with the phase boundary of ice melting being located under the debris cover. The main terms of the heat-balance equation for a glacier surface are solar radiation and convective heat transfer. The quantitative relationships characterizing the effect of glacier run-off augmentation from under a thin layer of debris cover are obtained for different bulk moraine concentrations inside the ice. The concept of equivalent time is introduced. It is defined as the time elapsed until the moment the sub-moraine ice-ablation rate becomes equal to the ablation rate of clean ice. This moment signifies the beginning of the shielding stage. Thus, a glacier can be considered as a self-controlling system with respect to its summer run-off. A series of numerical tests for Djankuat glacier, Central Caucasus, has been carried out. The dynamics of moraine-cover growth and alterations of seasonal ablation rate under debris show perfect agreement between the computed data and the results of 14 years of direct observations. Some practical recommendations concerning artificial blackening of a glacier surface for augmentation of liquid run-off are presented. Conditions promoting increase of run-off are: relatively high albedo, relatively low summer air temperature, and relatively small convective heat transfer between the air and the ice surface. The method of artificially blackening a glacier surface is by means of a durable thin dark polymer film. In conclusion, some further aspects of the problem are discussed.
TL;DR: A significant result is that the phase transition from one liquid-crystalline structure to another entails, as a rule, a reversible change in the catalytic activity of the solubilized enzyme.
Abstract: Instead of aqueous solutions, universally recognized in enzymology, ternary systems of the water/organic solvent/surfactant type are suggested as liquid-crystalline media for enzymatic reactions. Two systems, water/octane/Aerosol OT and water/cyclohexane/Brij 96, have been used to solubilize acid and alkaline phosphatases and peroxidase. The enzymes under study do function in liquid-crystalline mesophases having lamellar, cylindrical (reversed hexagonal) and ball-shaped (reversed cubic) packing of the surfactant molecules. A significant result is that the phase transition from one liquid-crystalline structure to another entails, as a rule, a reversible change in the catalytic activity of the solubilized enzyme.
TL;DR: In this paper, the multiplicity distributions of all charged and of negative particles for non-single-diffractive events in π+p and pp collisions at 250 GeV/c (s=22 GeV) are presented for various rapidity intervals.
TL;DR: A series of novel I(III) containing reagents have been developed and their electrophilic reactions with olefins giving vic-disubstituted derivatives (including vic -ditriflates) are described.
TL;DR: In this paper, the negative absorption coefficients of electromagnetic waves were calculated for non-relativistic and ultra-relatio-tivistic cases for the ring of charged particles circling in the equatorial plane of Kerr black holes.
Abstract: The mechanism of the energy extraction from charged particles moving in the vicinity of black holes due to the negative absorption of electromagnetic waves is considered. It is shown that there exist a number of resonant frequencies for which the ring of particles circling in the equatorial plane of Kerr black holes amplifies the incident electromagnetic waves. The negative absorption coefficients are calculated both for non-relativistic and ultrarelativistic cases.
TL;DR: In this paper, the properties of Bi2WO6 and Bi2MoO6 have been studied and discussed and some physical properties of single crystals and single-crystal ceramics are discussed.
Abstract: At low temperatures the compounds Bi2WO6 and Bi2MoO6, like many other related layered ferro-electrics, are electrically polar and transform to nonpolar state on heating. These phase transitions, however, are not ordinary ferroelectric ones and have a reconstructive nature. The two compounds undergo also additional phase transitions which are not accompanied with any noticeable changes in structure or polarization. Some physical properties of Bi2WO6 single crystals and Bi2MoO6 ceramics are studied and discussed.
TL;DR: In this paper, the present-day status of the giant dipole resonance (GDR) in light nuclei is discussed with main emphasis on the supermultiplet and configurational splitting of GDR, which are its most important features.
TL;DR: In this paper, a solution du probleme du champ magnetique dans la gaine magnetospherique pour une conductivite finie, ainsi que les valeurs du champ electrique soumis a l'effet du plasma du vent solaire, was determined.
Abstract: On determine une solution du probleme du champ magnetique dans la gaine magnetospherique pour une conductivite finie, ainsi que les valeurs du champ electrique soumis a l'effet du plasma du vent solaire
TL;DR: The efficiency and specificity of RNA-protein cross-linking in the 30S subunit of Escherichia coli ribosomes, induced by low-intensity and high-intensity ultraviolet radiation, are studied.
Abstract: The efficiency and specificity of RNA-protein cross-linking in the 30S subunit of Escherichia coli ribosomes, induced by low-intensity (1015 photons cm−2 s−1, 254 nm) and high-intensity [(1.6–6.8)×1024 photons cm−2 s−1, 266 nm, pulse duration 10−8 s] ultraviolet radiation, are studied. Under the former conditions proteins S4, S7 and S9/S11, and under the latter conditions these proteins together with S3, S18 and S20, are cross-linked to 16S RNA. Biphotonic processes operate in the latter case. In the presence of 2-mercaptoethanol cross-linking occurs either directly, via a higher excited state or via activated intermediates with life-times less than 25 ns. Crosslinks thus formed are specific, i.e. they are formed between regions of macromolecules which are in contact in the native (non-disturbed) complex prior to excitation. The efficiency of cross-linking (per photon absorbed) is 20–100 times higher upon two-step excitation as compared with single-step excitation and an analysable number of cross-links are produced in a single pulse. Only base U-1239 of 16S RNA is cross-linked to protein S7 by lowintensity radiation, whereas the adjacent base, G-1240 is also involved in laser-induced cross-linking. A transition from the former to the latter conditions allows one to reduce the duration of irradiation from several minutes to several nanoseconds.
TL;DR: The internal structure of the compact DNA particle in polymeric solvent is similar to that in the model of microcavity, where almost all added polymer is forced out from the globule.
Abstract: A theory of collapse of DNA considered as unifilar homopolymer is suggested. The collapse is interpreted as the coil-globule transition. Three reasons of the collapse such as the confinement in a m...
TL;DR: In this paper, a pseudocompact connected left-separated Tychonoff space with all subsets of cardinality ⩽τ closed and C ∗ -embedded is presented.
TL;DR: Cytochrome P‐450LM2 was isolated from rabbit liver microsomes in a form which was shown to be homogeneous in AcA‐22 Ultrogel and ultracentrifugation studies, and hexamer structure of the cytochrome was directly demonstrated by electron microscopic study.
TL;DR: The observed effects seem likely to reflect the existence of the potential-dependent regulation of the bacteriorhodopsin photocycle in intact purple membranes.
TL;DR: In this article, the EDA-resistant Anabaena variabilis (ED81, ED92) had low levels of glutamine synthetase (GS) biosynthetic activity compared with the wild type strain.
Abstract: Ethylenediamine (EDA) is toxic to the cyanobacterium Anabaena variabilis and inhibits nitrogenase activity. The inhibition of nitrogenase was prevented by pretreatment of cells with l-methionine-d,l-sulphoximine (MSX). Mutant strains of Anabaena variabilis (ED81, ED92), resistant to EDA, had low levels of glutamine synthetase (GS) biosynthetic activity compared with the wild type strain. ED92 had a low level of GS protein whereas ED81 had a similar level to that of the parent strain as estimated using antibodies against GS. Both strains fixed N2 and liberated NH4+ into the media. Following immobilization of the mutant strains, sustained photoproduction of NH4+ was obtained in air-lift reactors at rates of up to 50 μmol NH4+ mg chl a−1 h−1, which were comparable to the rates obtained when immobilized cyanobacteria were treated with MSX.
TL;DR: In this article, the main results for queueing systems with repeated calls obtained up to now only for single-line queuing systems have been given, and the results for repeated calls for multiple-line queues have been discussed.
Abstract: In the paper we give main results for queueing systems with repeated calls obtained up till now only for single-line queueing systems.
TL;DR: In this paper, the authors show that 2-naphthyl-substituted 1,3-diketoboronates exhibit high fluorescence quantum yields.
TL;DR: In this paper, the potential energy of the interaction of the molecules with the lattice of the Na-X zeolite was calculated in the atom-atom approximation and the resulting potential energy was obtained as a sum of the contributions of the dispersion, repulsion and polarization energy.
TL;DR: In this article, the authors describe diffraction focusing of the spherical X-ray radiation, experimentally discovered outside the crystal with a temperature gradient or ultrasound oscillations in it, and show that the focus distance decreases with the rise of the temperature gradient if it is antiparallel to the diffraction vector.
TL;DR: In this paper, a complete description of the Hamiltonian operators is given and a ⪡Darboux lemma for systems with infinite degrees of freedom is proved for some values of the parameters.