Showing papers by "Moscow State University published in 1994"
TL;DR: The signature analysis ofreflectance spectra indicated that in the green to yellow leaves of both species the maximal standard deviation of reflectance coincided with the red absorption maximum of Chl a .
1,029 citations
TL;DR: In this article, the signature analysis of reflectance spectra of autumn Aesculus hippocastanum L and Acer platanoides L leaves revealed spectral bands maximally (near 550 and 705 nm) and minimally (at more than 750 nm) sensitive to variation in chlorophyll content, which can serve as sensitive indicators of early stages of leaf senescence.
Abstract: The signature analysis of reflectance spectra of autumn Aesculus hippocastanum L and Acer platanoides L leaves revealed spectral bands maximally (near 550 and 705 nm) and minimally (at more than 750 nm) sensitive to variation in chlorophyll content, which can serve as sensitive indicators of early stages of leaf senescence Several functions of reflectance directly proportional to chlorophyll-a have been found These make it possible to determine chlorophyll accurately with a background of high pigment concentration
601 citations
TL;DR: In this paper, the principles underlying the observed effects of applied pressure on biological systems, and the current and potential application of pressure in biotechnological processes are discussed. But the authors focus on applying pressure to biological systems and processes to modify the properties of biological materials to preserve or improve their qualities.
302 citations
TL;DR: From a review of the physiological and psychological evidence, it is concluded that no subtraction, compensation, or evaluation need take place and the problem for which these solutions were developed turns out to be a false one.
Abstract: We identify two aspects of the problem of maintaining perceptual stability despite an observer's eye movements. The first, visual direction constancy, is the (egocentric) stability of apparent positions of objects in the visual world relative to the perceiver. The second, visual position constancy, is the (exocentric) stability of positions of objects relative to each other. We analyze the constancy of visual direction despite saccadic eye movements.Three information sources have been proposed to enable the visual system to achieve stability: the structure of the visual field, proprioceptive inflow, and a copy of neural efference or outflow to the extraocular muscles. None of these sources by itself provides adequate information to achieve visual direction constancy; present evidence indicates that all three are used.Our final question concerns how information processing operations result in a stable world. The three traditionally suggested means have been elimination, translation, or evaluation. All are rejected. From a review of the physiological and psychological evidence we conclude that no subtraction, compensation, or evaluation need take place. The problem for which these solutions were developed turns out to be a false one. We propose a “calibration” solution: correct spatiotopic positions are calculated anew for each fixation. Inflow, outflow, and retinal sources are used in this calculation: saccadic suppression of displacement bridges the errors between these sources and the actual extent of movement.
293 citations
TL;DR: In this paper, high-Q optical whispering-gallery modes TE(TM)lmq in spheroidal dielectric microresonators are shown to be equivalent to precessing circular modes with the rate of precession depending on the value of the residual resonator nonsphericity.
250 citations
TL;DR: In this paper, the authors analyzed the properties of damage-resistant LiNbO3 crystals doped with Mg, Zn, or In. Damage resistance is due to an essential increase in the photoconductivity σp.
Abstract: We analyzed the properties of damage-resistant LiNbO3 crystals doped with Mg, Zn, or In. Damage resistance is due to an essential increase in the photoconductivity σp. In the first two compounds the increase in σp is most pronounced at concentrations exceeding certain thresholds (5.5 mol. % MgO or 7 mol. % ZnO in the congruent melt), whereas in In-doped crystals it occurs at any In concentration. The increase in σp is directly related to the reduction of the intrinsic defects NbLi because of their substitution by damage-resistant impurities. If an iron impurity is present, then an abrupt decrease in the capture cross section of Fe3+ acceptors at Mg or Zn concentrations higher than the threshold is responsible for the observed increase in σp.
231 citations
TL;DR: In this article, a molecular model consistent with theoretical predictions on how to connect cylindrical tubule segments is provided, which is probably caused by the occurrence along the helix of pairs of pentagon-heptagon carbon rings in the hexagonal network.
Abstract: The growth of micron-size carbon fibres from thermal decomposition of hydrocarbons catalyzed by a metal has been widely studied. Coil-shaped fibres often grow among straight or twisted filaments. Their internal structure has not been studied in detail as yet. In the present work, the thermal cracking of acetylene on Co nanoparticles dispersed on porous silica has produced relatively well graphitized hollow nanotubules, including straight filaments and regular helices. The small diameter of the coiled tubules and the absence of an amorphous coating allowed a determination of their texture by transmission electron microscopy (TEM). The coiled tubules consist of regularly polygonized, coaxial graphene tubes whose angular bends are aligned. The bends are probably caused by the occurrence along the helix of pairs of pentagon-heptagon carbon rings in the hexagonal network. Such a structure was recently predicted to be a thermodynamically stable topology for helical, single-sheet carbon tubes. A molecular model, consistent with theoretical predictions on how to connect cylindrical tubule segments, is provided.
210 citations
TL;DR: In this article, the electropolymerization of substituted anilines (anthranilic acid, m-aminobenzoic acid and m-ammonobenzenesulphonic acid) was studied.
208 citations
191 citations
TL;DR: It is concluded that the CtpA protein is a processing enzyme that cleaves off the C-terminal extension of the D1 protein, which shows significant sequence similarity to the interphotoreceptor retinoid-binding proteins in the bovine, human, and insect eye systems.
Abstract: The D1 protein of the photosystem II (PSII) complex in the thylakoid membrane of oxygenic photosynthetic organisms is synthesized as a precursor polypeptide (pD1) with a C-terminal extension. Posttranslational processing of the pD1 protein is essential to establish water oxidation activity of the PSII complex. We have recently identified a gene, ctpA, a mutation in which resulted in a loss of PSII activity in the cyanobacterium Synechocystis sp. PCC 6803. To study the function of the CtpA protein, we inactivated the ctpA gene by inserting a kanamycin-resistance gene into its coding sequence. The resultant mutant strain, T564, had no PSII-mediated water oxidation activity, but it had normal cytochrome b6f and photosystem I activities. Measurements of thermoluminescence profiles and rates of reduction of 2,6-dichlorophenolindophenol indicated that PSII complexes in the mutant cells had functional reaction centers that were unable to accept electrons from water. Immunoblot analysis showed that D1, D2, CP47, CP43, and the alpha subunit of cytochrome b559, five integral membrane proteins of PSII, were present in T564 cells. Interestingly, the D1 protein in the mutant cells was 2 kDa larger than that in wild-type cells, due to the presence of a C-terminal extension. We conclude that the CtpA protein is a processing enzyme that cleaves off the C-terminal extension of the D1 protein. Interestingly, the CtpA protein shows significant sequence similarity to the interphotoreceptor retinoid-binding proteins in the bovine, human, and insect eye systems.
191 citations
TL;DR: ' If the temperature T and the junction capacitances C& (j = 1,2 } are small enough, then the tunneling events become correlated.
Abstract: The paper is devoted to calculation of the ``classical'' (thermal and/or shot) intrinsic noise of the single-electron transistor (SET) caused by the stochastic character of electron tunneling. Exact solution of the master equation describing the dynamics of the SET is obtained in the frequency representation. The low-frequency limit for the spectral calculations is considered in detail.
TL;DR: In this article, the authors measured the elastic light vector meson cross sections at an average υp center of mass energy of 180 GeV with the ZEUS detector at HERA.
Abstract: Photon proton cross sections for elastic light vector meson production, σelνp, inelastic diffractive production, σndνp, non-diffractive production, σdνp, as well as the total cross section, σtotνp, have been measured at an average υp center of mass energy of 180 GeV with the ZEUS detector at HERA. The resulting values are σelνp = 18 ± 7 μb, σdνp = 33 ± 8 μb, σndνp = 91 ± 11 μb, and σtotνp 143 ± 17 μb, where the errors include statistical and systematic errors added in quadrature.
TL;DR: In this paper, a first generation amperometric glucose biosensor based on Prussian Blue modified electrodes was developed, which exhibited linear response dependence on analyte concentration in a range of 10−6 − 5·10−3 M glucose.
Abstract: A first generation amperometric glucose biosensor based on Prussian Blue modified electrodes was developed. Besides exception of noble metals (platinum as usual) the developed biosensor possessed high sensitivity. Linear response dependence on analyte concentration was observed in a range of 10−6 − 5·10−3 M glucose. The current density produced by addition of 10−6 M glucose was 0.18 μ A/cm2. Hydrogen peroxide produced via enzyme reaction was detected by electroreduction. Owing to that reason the biosensor response became independent of the presence of reductants (ascorbate for example). The developed amperometric biosensor was expected to obey requirements for non-invasive diagnostics. There are not principle limits of using other oxidases for Prussian Blue based amperometric biosensor development. Thus one can develop such biosensors for cholesterol, alcohol, glycerol, amino acids ets.
TL;DR: The 348K protein of BYV is longer than the putative replicases of the most closely related viruses by about 1300 amino acids distributed between two unique regions, one at the N-terminus, and the other in the central portion.
TL;DR: The pattern of the present results suggests that sensory-memory traces, as reflected by the MMN, integrate information about two closely spaced stimuli into a unitary sensory event.
TL;DR: Brownian motion is a familiar classroom demonstration as mentioned in this paper and it was discovered as early as 1827 by a British botanist called Robert Brown who was the first to report incessant chaotic movement of pollen particles suspended in liquid.
Abstract: Brownian motion is a familiar classroom demonstration. This phenomenon was discovered as early as 1827 by a British botanist called Robert Brown who was the first to report incessant chaotic movement of pollen particles suspended in liquid.
TL;DR: The primary radiobiological effects connected with irradiation of organisms are considered and secondary disturbances due to changes of ecological bonds between the components of irradiated forest ecosystem are discussed.
TL;DR: In this article, Nafion polyelectrolyte electrodes were used for the electrocatalytic oxidation of NADH and achieved an optimal working potential of 0 to 100 mV (vs. SCE) and operation stability.
Abstract: Poly(methylene blue) (PMB)-modified electrodes show excellent properties for the electrocatalytic oxidation of NADH concerning the optimal working potential of 0 to 100 mV (vs. SCE)and their operation stability. By means of dehydrogenases entrapped within a Nafion film on top of the PMB layer, new amperometric biosensors for glucose, lactate, malate, and ethanol could be obtained with improved integration of the enzyme and the electrocatalyst directly on the electrode surface. Coentrapment of the negatively charged NAD+ within the negatively charged Nafion Polyelectrolyte leads to reagentless dehydrogenase electrodes for one-shot or short-term applications.
TL;DR: A new family of iterative methods for solving symmetric positive definite systems based on B-reducing strategies is described, and numerical results are presented for the new algorithms and compared with several well-known preconditioned CG methods.
Abstract: Instead of the standard estimate in terms of the spectral condition number we develop a new CG iteration number estimate depending on the quantity B = 1/ntr M/(det M)1/n, where M is an n × n preconditioned matrix. A new family of iterative methods for solving symmetric positive definite systems based on B-reducing strategies is described. Numerical results are presented for the new algorithms and compared with several well-known preconditioned CG methods.
TL;DR: In this paper, the coefficient functions of the gluon condensate in the correlators of heavy-quark vector, axial, scalar and pseudoscalar currents, are obtained analytically, to two loops, for all values of z = q 2 4m 2.
TL;DR: In this paper, the theory of collapse of weakly charged polyelectrolyte gels is generalized by taking into account the possibility of counter ion trapping with the formation of ion pairs, which becomes progressively important as the gel shrinks and the dielectric constant of the gel medium decreases.
Abstract: The theory of collapse of weakly charged polyelectrolyte gels is generalized by taking into account the possibility of counter ion trapping with the formation of ion pairs, which becomes progressively important as the gel shrinks and the dielectric constant of the gel medium decreases. A phenomenon well known in the theory of ionomers, namely the aggregation of ion pairs due to dipole-dipole interactions with the formation of multiplets, is also taken into account. These multiplets act as additional physical cross-links. It is shown that accounting for the two effects mentioned above generally leads to an increase of the region of stability of the collapsed phase and to an increase of the jump in volume at the transition point. The most important, qualitatively new effect is the possibility of existence of a new supercollapsed state of a polymer gel which is very close to the densely packed dry gel. The reason for the thermodynamic stability of the supercollapsed state is a loop of positive feedback: the decrease of the volume of the gel leads to a decrease of the dielectric constant and hence to progressive formation of ion pairs, thus the concentration of mobile counter ions and the corresponding osmotic pressure decrease, the gel shrinks further etc. It is possible to realize the phase transitions between all three states of a polymer gel: swollen, ordinary collapsed and supercollapsed.
TL;DR: In this article, the effect of light-induced modification of the optical properties of photochromic liquid crystalline (side-group) polymers (LCPs) containing azobenzene moieties was studied.
Abstract: The light-induced modification of the optical properties of photochromic liquid crystalline (side-group) polymers (LCPs) containing azobenzene moieties was studied. Films of such polymers were irradiated with unpolarized and linearly polarized light. Unpolarized irradiation results in a modification of the order parameter, whereas the director orientation remains constant. The light-induced disturbance of the supramolecular order is strongly dependent on the structure of the polymer. A correlation with the enthalpic stability of the liquid crystalline phases is given. Linearly polarized irradiation causes a modification of the order parameter and a reorientation of the side-groups towards a direction perpendicular to the electric vector of the actinic light. This reorientation process is caused by an angular-dependent photoselection within the steady state of the photoisomerization of the azobenzene units. The amount and kinetic of the reorientation differ considerably as a function of certain structural features of the polymers, such as the content of photochromic moieties and the lengths of the spacer chains between the polymeric backbone and the rod-like moieties. It is shown that under certain circumstances the angular-dependent photoselection process may cause a reorientation of the non-photochromic moieties by a cooperative process. The result is a light-induced rotation of the optical axis of the LCP and thus an efficient modification of the birefringent and dichroic properties. This effect can be used in optical data storage.
TL;DR: In this paper, the factors which determine the electrocatalytic activity of metals in the hydrogen reaction are described. The problems are formulated which arise when plotting the volcano relationship between the current density logarithm and the metal-hydrogen bond energy.
TL;DR: The ten-parametric internal symmetry group is found in the Einstein-Maxwell-dilaton-axion theory restricted to space-times admitting a Killing vector field and includes dilaton-AXion SL(2,[ital R]) duality and Harrison-type transformations which are similar to some target-space duality boosts, but act on a different set of variables.
Abstract: The ten-parametric internal symmetry group is found in the D=4 Einstein-Maxwell-dilaton-axion theory restricted to space-times admitting a Killing vector field. The group includes dilaton-axion SL(2,R) duality and Harrison-type transformations which are similar to some target-space duality boosts, but act on a different set of variables. A new symmetry is used to derive a seven-parametric family of rotating dilaton-axion Taub-NUT dyons.
TL;DR: In this paper, a new magnetic field induced phase transition between the space-modulated spin structure (SMSS) and the homogeneous antiferromagnetic state (HAFS) is reported.
Abstract: The discovery of a new magnetic field induced phase transition between the space-modulated spin structure (SMSS) and the homogeneous antiferromagnetic state (HAFS) is reported. This phase transition is accompanied by large magnetoelectric (ME) anomalies. It is well known that BiFeO, shows the ferroelectric ordering (T c = 1083 K) and antiferromagnetic ordering (T N = 673 K). ME properties of BiFeO3 so far remain a challenging experimental and theoretical problem. While the crystal symmetry of BiFeO3 allows a linear ME effect, it cannot be observed because the antiferromagnetic order of BiFeO3 is SMSS (cycloid). We show that there is a Lifshits invariant, which decreases the ground state energy and induces the SMSS. In a high magnetic field the energy of the HAFS decreases more rapidly than the energy of the SMSS. Hence the field induced phase transition between SMSS and HAFS is possible. We stress that a large variation of the ME effect is expected at the transition due to a rising linear ME cont...
TL;DR: In this paper, a theoretical investigation of heat and mass transfer during evaporation in a wet capillary structure in contact with a heating wall is presented, where the wall has grooves by which the vapour is removed.
TL;DR: The data strongly support the notion that the region of polypeptide 2C involved in the NTP utilization is affected by the guanidine mutations and by the presence of the drug itself, and allow us to propose that oligomerization ofpolypeptides 2C is an essential step in the replication of viral genome.
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TL;DR: In this paper, it was shown that any two isomorphic superalgebras with different Cartan matrices have isomorphic q-deformations and their standard comultiplications are connected by such twisting.
Abstract: We show that some factors of the universal R-matrix generate a family of twistings for the standard Hopf structure of any quantized contragredient Lie (super)algebra of finite growth. As an application we prove that any two isomorphic superalgebras with different Cartan matrices have isomorphic q-deformations (as associative superalgebras) and their standard comultiplications are connected by such twisting. We present also an explicit relation between the generators of the second Drinfeld's realization and Cartan-Weyl generators of quantized affine nontwisted Kac-Moody algebras. Further development of the theory of quantum Cartan-Weyl basis, closely related with this isomorphism, is discussed. We show that Drinfeld's formulas of a comultiplication for the second realization are a twisting of the standard comultiplication by factors of the universal R-matrix. Finally, properties of the Drinfeld's comultiplication are considered.
TL;DR: In this article, a walking vehicle with two telescopic legs was designed at the Institute of Mechanics at Moscow University, where a computer, hardware servosystems, and power amplifiers were used to control the vehicle.
Abstract: This article describes a walking vehicle with two telescopic legs that was designed at the Institute of Mechanics at Moscow University. The vehicle is driven by two DC drives. Its con trol system comprises a computer, hardware servosystems, and power amplifiers. An adaptive algorithm has been developed for control of vehicle locomotion. This algorithm is based on the tracking of the commanded path. A part of the path is planned by the computer in advance using a mathematical model of the vehicle. The rest is built up during walking of the vehicle based on the information on its state. In the ex periments, the designed control algorithm was successfully implemented.