Showing papers by "Moscow State University published in 1996"
TL;DR: In this article, a green vegetation index, tailored on the concept of ARVI (Kaufman and Tanre, 1992), is developed and is expected to be as resistant to atmospheric effects as ARVI but more sensitive to a wide range of Chl-a concentrations.
1,907 citations
TL;DR: It is demonstrated that quality factor Q - (0.8 +/- 0.1) x 10(10) of whispering-gallery modes in fused-silica microspheres at 633 nm, close to the ultimate level determined by fundamental material attenuation as measured in optical fibers, is demonstrated.
Abstract: We demonstrate the quality factor Q - (0.8 +/- 0.1) x 10(10) of whispering-gallery modes in fused-silica microspheres at 633 nm, close to the ultimate level determined by fundamental material attenuation as measured in optical fibers. The lifetime of ultimate Q is limited by adsorption of atmospheric water. Monitoring of adsorption kinetics with submonolayer sensitivity by Q factors and frequencies of whispering-gallery modes is demonstrated. The possibility of supermaterial Q's owing to intrinsic suppression of scattering losses in micropheres is discussed.
986 citations
TL;DR: A model for collisions between particles of a granular material is proposed and it is found that the type of collision is determined by the impact velocity and by the surface properties of the colliding grains.
Abstract: We propose a model for collisions between particles of a granular material and calculate the restitution coefficients for the normal and tangential motion as functions of the impact velocity from considerations of dissipative viscoelastic collisions. Existing models of impact with dissipation as well as the classical Hertz impact theory are included in the present model as special cases. We find that the type of collision (smooth, reflecting or sticky) is determined by the impact velocity and by the surface properties of the colliding grains. We observe a rather nontrivial dependence of the tangential restitution coefficient on the impact velocity. \textcopyright{} 1996 The American Physical Society.
725 citations
TL;DR: In this article, the spectral properties of plant leaves were investigated to develop spectral indices more sensitive to chlorophyll concentration than the presently widely used Notmalized Difference Vegetation Index.
724 citations
TL;DR: In this article, a concept is put forward that non-phosphorylating (uncoupled or non-coupled) respiration takes part in maintenance of low levels of both O2 and the O2 reductants when the normal respiration fails to do this job due to lack of ADP.
Abstract: To proceed at a high rate, phosphorylating respiration requires ADP to be available. In the resting state, when the energy consumption is low, the ADP concentration decreases so that phosphorylating respiration ceases. This may result in an increase in the intracellular concentrations of O2 as well as of one-electron O2 reductants such as These two events should dramatically enhance non-enzymatic formation of reactive oxygen species, i.e. of , and OH, and, hence, the probability of oxidative damage to cellular components. In this paper, a concept is put forward proposing that non-phosphorylating (uncoupled or non-coupled) respiration takes part in maintenance of low levels of both O2 and the O2 reductants when phosphorylating respiration fails to do this job due to lack of ADP.In particular, it is proposed that some increase in the H+ leak of mitochondrial membrane in State 4 lowers , stimulates O2 consumption and decreases the level of which otherwise accumulates and serves as one-electron O2 reductant. In this connection, the role of natural uncouplers (thyroid hormones), recouplers (male sex hormones and progesterone), non-specific pore in the inner mitochondrial membrane, and apoptosis, as well as of non-coupled electron transfer chains in plants and bacteria will be considered.
668 citations
TL;DR: In this paper, high spectral resolution reflectance measurements were acquired for spring, summer and autumn maple and chestnut leaves covering a wide range of chlorophyll content and consistent and diagnostic differences in the red edge range (680-750 nm) of the reflectance spectrum were obtained for the various leaf samples of both species studied.
447 citations
TL;DR: It is proposed that ROS‐induced pore opening lowers ROS production due to maximal stimulation of mitochondrial O2 consumption and, hence, intracellular [O2] lowering and (b) complete dissipation of mitochondrial membrane potentials and, as a consequence, maximal oxidation of such respiratory chain carriers as CoQ.
383 citations
TL;DR: The East European Craton was affected by rift phases during Early, Middle and Late Riphean, early Vendian, early Palaeozoic, Early Devonian and Middle-Late Devonian times and again at the transition from the Carboniferous to the Permian and the permian to the Triassic as discussed by the authors.
379 citations
TL;DR: In this paper, block ionomer complexes formed between the block copolymers containing poly(sodium methacrylate) (PMANa) and poly(ethylene oxide) (PEO) segments and poly (N-ethyl-4-vinylpyridinium bromide) (PEVP) were investigated.
Abstract: Block ionomer complexes formed between the block copolymers containing poly(sodium methacrylate) (PMANa) and poly(ethylene oxide) (PEO) segments and poly(N-ethyl-4-vinylpyridinium bromide) (PEVP) were investigated. The data obtained suggest that (i) these systems form water-soluble stoichiometric complexes; (ii) these complexes are stable in a much broader pH range compared to the polyelectrolyte complexes prepared from homopolymers; (iii) they self-assemble to form the core of a micelle comprised of neutralized polyions, surrounded by the PEO corona; (iv) they are salt sensitive since they fall apart as the salt concentration increases beyond a critical value; and (v) they can participate in the cooperative polyion substitution reactions. Therefore, these complexes represent a new class of hybrid materials which combine properties of polyelectrolyte complexes and block copolymer micelles.
370 citations
TL;DR: In this paper, an airborne radio-echo survey of ice depths over central East Antarctica led to the discovery of a sub-ice lake of unknown depth and composition, with an area of about 10,000km2 and lying beneath ∼4km of ice.
Abstract: IN 1974–75, an airborne radio-echo survey of ice depths over central East Antarctica led to the discovery of a sub-ice lake of unknown depth and composition, with an area of about 10,000km2 and lying beneath ∼4km of ice1. In 1993, altimetric data from satellite measurements2 provided independent evidence of the lake's areal extent, thus confirming it to be the largest known sub-ice lake by an order of magnitude. Here we analyse new altimetric and radio-echo data, along with existing seismic data3, to show that the lake is deep (mean depth of 125 m or more) and fresh, and that it has an area that exceeds previous estimates by about 50%—dimensions comparable with those of Lake Ontario. We estimate that the residence time of the water in the lake is of the order of tens of thousands of years, and that the mean age of water in the lake, since deposition as surface ice, is about one million years. Regional ice-dynamics can be explained in terms of steady-state ice flow along and over the lake.
342 citations
TL;DR: The history of the theory of quantum nondemolition (QND) measurements from the 1920s until today is reviewed in this paper, where the definition and main principles of QND measurements are outlined.
Abstract: The history of the theory of quantum nondemolition (QND) measurements from the 1920s until today is reviewed. The definition and main principles of QND measurements are outlined. Achievements in the experimental realization of QND measurements and several new promising schemes of QND measurements are described. A list of the most important problems (from the authors' point of view) in the area of QND measurements is presented. The problem of measurement of a quantum oscillator phase is considered. A new method of phase measurement is proposed. Examples of possible solutions of fundamental physical problems using QND methods are given.
TL;DR: The authors' experience with the application of the needle optimization technique to the design of optical coating is summarized and a physical interpretation of the technique is provided.
Abstract: The authors' experience with the application of the needle optimization technique to the design of optical coating is summarized. A physical interpretation of the technique is provided, and its main features are identified. Guidelines on the application of the needle optimization technique to various types of design problems are given.
TL;DR: In this paper, the authors observed giant double-stranded DNA chains by fluorescence microscopy in an aqueous environment and found that the coil-globule transition of T4DNA, 166kbp, induced by spermidine is markedly discrete for individual chains, and continuous for their ensemble average.
Abstract: We observed giant double-stranded DNA chains by fluorescence microscopy in an aqueous environment. We found that the coil-globule transition of T4DNA, 166kbp, induced by spermidine is markedly discrete for individual chains, and continuous for their ensemble average. Simple theoretical consideration is given taking account of the hierarchy of the system. It is suggested that the unique characteristics of the transition for long DNA has a general significance for the coil-globule transition in other biological and synthetic ``stiff polymers.''
06 May 1996
TL;DR: In this article, the authors demonstrate the quality factor Q = (08 plus or minus 1) multiplied by 1010 whispering gallery modes in fused silica microspheres at 633 nm, close to the limit determined by fundamental material attenuation.
Abstract: We demonstrate the quality factor Q equals (08 plus or minus 01) multiplied by 1010 of whispering-gallery modes in fused silica microspheres at 633 nm, close to the limit determined by fundamental material attenuation The lifetime of ultimate Q is limited by adsorption of atmospheric water Optical effects of adsorption are investigated and conditions for fabrication of long-lifetime microspheres are clarified© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering Downloading of the abstract is permitted for personal use only
TL;DR: In this article, the influence of the glacial anticyclonic circulation attenuated through the late glacial period, and the Westerlies gradually shifted northward, such that drier conditions south of the ice sheet were confined to a progressively narrower zone and the Mediterranean became drier.
TL;DR: A significant increase in lifespan and inhibition of tumour growth inhibition was observed in animals with Sp2/0 tumours with EPI/P85 and DOX/L61 compositions and the data suggest that higher activity is associated with more hydrophobic copolymers.
Abstract: The chemosensitising effects of poly(ethylene oxide)-poly(propylene oxide)-poly-(ethylene oxide) (PEO-PPO-PEO) block copolymers (Pluronic) in multidrug-resistant cancer cells has been described recently (Alakhov VY, Moskaleva EY, Batrakova EV, Kabanov AV 1996, Biocon. Chem., 7, 209). This paper presents initial studies on in vivo evaluation of Pluronic copolymers in the treatment of cancer. The anti-tumour activity of epirubicin (EPI) and doxorubicin (DOX), solubilised in micelles of Pluronic L61, P85 and F108, was investigated using murine leukaemia P388 and daunorubicin-sensitive Sp2/0 and -resistant Sp2/0(DNR) myeloma cells grown subcutaneously (s.c.). The study revealed that the lifespan of the animals and inhibition of tumour growth were considerably increased in mice treated with drug/copolymer compositions compared with animals treated with the free drugs. The anti-tumour activity of the drug/copolymer compositions depends on the concentration of the copolymer and its hydrophobicity, as determined by the ratio of the lengths of hydrophilic PEO and hydrophobic PPO segments. The data suggest that higher activity is associated with more hydrophobic copolymers. In particular, a significant increase in lifespan (T/C> 150%) and tumour growth inhibition (> 90%) was observed in animals with Sp2/0 tumours with EPI/P85 and DOX/L61 compositions. The effective doses of these compositions caused inhibition of Sp2/0 tumour growth and complete disappearance of tumour in 33-50% of animals. Future studies will focus on the evaluation of the activity of Pluronic-based compositions against human drug-resistant tumours.
TL;DR: In this article, a significant correlation between the magnetic and rotational moments for a sample of 112 lower main-sequence stars was found, with a Pearson correlation coefficient of about + 0.5-0.6.
Abstract: We find a significant correlation between the magnetic and rotational moments for a sample of 112 lower main-sequence stars. The rotational moment is calculated from measurements of the rotation period in most of the stars (not from the projected rotational velocity inferred from Doppler broadening). The magnetic moment is computed from a database of homogeneous measurements of the mean level of Ca II H and K emission fluxes sampled for most of the stars over an interval of 25 yr. The slope connecting the logarithm of the magnetic moment and the logarithm of the rotational moment is about +0.5-0.6, with a Pearson correlation coefficient of about +0.9. The scatter of points from the mean relation has a component that is natural and caused by decade-long surface variability.
TL;DR: A new biosensor for the direct detection of organophosphorus (OP) neurotoxins has been developed utilizing cryoimmobilized, recombinant E. coli cells capable of hydrolyzing a wide spectrum of OP pesticides and chemical warfare agents.
TL;DR: In this paper, the theory of laser excitation of acoustic waves by absorbing of light in particles, dispersed in transparent, light-absorbing or scattering media, is developed and the distribution of light absorption can be obtained from the temporal course of acoustic pressure.
Abstract: The methods of time-resolved laser optoacoustic tomography of inhomogeneous media and related problems are reviewed. Time-resolved laser optoacoustic tomography allows one to measure the distribution of light absorption in turbid media with depth resolution up to several microns in real time. The theory of laser excitation of acoustic waves by absorbing of light in particles, dispersed in transparent, light-absorbing or scattering media, is developed. The distribution of light absorption can be obtained from the temporal course of acoustic pressure. Two schemes of acoustic wave detection — in the medium under testing (direct detection) and in transparent medium, coupled to the investigated one (indirect detection) — are discussed. In both cases the reconstruction of light absorption can be made by simple calculations. Test experiments with homogeneous and layered media confirm the proposed theoretical models and the possibility of using the proposed experimental schemes. Light absorption in homogeneous, inhomogeneous media and in absorbing particles dispersed in turbid media was investigated. The experimental setup allows one to measure the absorption coefficients over the range 1-500 cm−1 with the depth resolution 10–15 μm over the depth 1–1.5 mm.
TL;DR: Explicit formulas for the solutions of the recurrence relations for 3-loop vacuum integrals are suggested in this paper, which can also be used for direct calculations and demonstrate a high efficiency.
TL;DR: In this paper, the use of the intensive mass transfer reactor (IMTR) for enzymatic saccharification of cellulose, where the reaction mixture is intensively stirred by ferromagnetic particles (FMP), enhances the process rate and productivity drastically.
Abstract: The use of the intensive mass transfer reactor (IMTR) for enzymatic saccharification of cellulose, where the reaction mixture is intensively stirred by ferromagnetic particles (FMP), enhances the process rate and productivity drastically. The most significant enhancement of the process was observed when microcrystalline cellulose was used as a substrate. A concentration of sugars up to 5% was obtained after 1 h of cellulose hydrolysis using a cellulase activity level of 2 filter paper units (FPU)/mL (20 FPU/g substrate). In the hydrolysis of two types of industrial cellulosic wastes, the enhancement effects were less pronounced. Parameters related to the IMTR design, such as the shape, dimensions, and mass of FMP, as well as the magnetic field strength, strongly affected the process of hydrolysis. Among various kinds of FMP tested, the most efficient were found to be cylindrical particles (0.25 x 4 mm). In general, the hydrolysis rate enhanced when the magnetic field strength increased from 26,000 to 64,000 A/m. An optimal FMP loading existed at each level of the field strength. Hydrolyzates obtained in the IMTR under the action ofTrichoderma reesei andPenicillium verruculosum cellulases contained glucose and cellobiose as soluble products, cellobiose being predominant (> 50%). Only when a high level of extra Β-glucosidase was added to the IMTR (10 CBU/mL), did glucose made up more than 90% of the products. Owing to extreme shear conditions in the IMTR, significant enzyme inactivation took place.
TL;DR: In this paper, it was shown that and are algebraically independent and Bertrand's conjecture on algebraic independence over of the values at algebraic points of a modular function and its derivatives.
Abstract: We prove results on the transcendence degree of a field generated by numbers connected with the modular function . In particular, we show that and are algebraically independent and we prove Bertrand's conjecture on algebraic independence over of the values at algebraic points of a modular function and its derivatives.
TL;DR: In this article, analytical solutions of the equations for the radiation force induced by nonlinear focused ultrasound in a dissipative medium are considered. And the initiation of acoustical streaming by radiation force is considered, and the spatial and temporal characteristics of induced flow are discussed.
Abstract: Based on asymptotic methods recently developed in nonlinear acoustics, analytical solutions of the equations for the radiation force induced by nonlinear focused ultrasound in a dissipative medium are considered. Equations describing spatial structure of the radiation force field in the paraxial region of the ultrasound beam and the spatial–temporal behavior of the induced nonlinear streaming are derived. The equations enable analytical investigation of dependencies of radiation pressure and resulting streaming on the acoustic field and medium parameters. Estimates have shown that nonlinearity of medium can significantly enhance radiation force in the focal region at the intensities lower than those used in ultrasound devices for medical imaging. The initiation of acoustical streaming by radiation force is considered, and the spatial and temporal characteristics of induced flow are discussed. Both acoustic and hydrodynamic nonlinearities are taken into account. The paper concludes by discussing possible m...
TL;DR: Results of phylogenetic analyses provide very strong bootstrap support for monophyly of both spermatophytes and angiosperms and for a basal position for the aquatic angiosperm Nymphaea among angios perms studied was observed.
Abstract: We developed PCR primers against highly conserved regions of the rRNA operon located within the inverted repeat of the chloroplast genome and used these to amplify the region spanning from the 3' terminus of the 23S rRNA gene to the 5' terminus of the 5S rRNA gene. The sequence of this roughly 500-bp region, which includes the 4.5S rRNA gene and two chloroplast intergenic transcribed spacer regions (cpITS2 and cpITS3), was determined from 20 angiosperms, 7 gymnosperms, and 16 ferns (21,700 bp). Sequences for the large subunit of ribulose bisphosphate carboxylase/oxygenase (rbcL) from the same or confamilial genera were analyzed in both separate and combined data sets. Due to the low substitution rate in the inverted repeat region, noncoding sequences in the cpITS region are not saturated with substitutions, in contrast to synonymous sites in rbcL, which are shown to evolve roughly six times faster than noncoding cpITS sequences. Several length polymorphisms with very clear phylogenetic distributions were detected in the data set. Results of phylogenetic analyses provide very strong bootstrap support for monophyly of both spermatophytes and angiosperms. No support for a sister group relationship between Gnetales and angiosperms in either cpITS or rbcL data was found. Rather, weak bootstrap support for monophyly of gymnosperms studied and for a basal position for the aquatic angiosperm Nymphaea among angiosperms studied was observed. Noncoding sequences from the inverted repeat region of chloroplast DNA appear suitable for study of land plant evolution.
TL;DR: In this article, a statistically significant decrease has been found in 60% of the time series of global radiation annual totals obtained from 160 actinometric stations in the former Soviet Union (FSU).
Abstract: Regular measurements of solar radiation carried out in the network of actinometric stations of the former Soviet Union (FSU) have shown a decreasing tendency in the time series of direct and global solar radiation during last decades. A statistically significant decrease has been found in 60% of the time series of global radiation annual totals obtained from 160 actinometric stations. Three large areas, where this decrease exceeded 2% per 10 years, were found (in the European part of the FSU, in West Siberia, and in the Far East). As the main reason for changes in solar radiation, increased cloudiness and atmospheric turbidity are considered. A more detailed analysis of long-term changes in radiation budget components obtained from two stations situated in rather different conditions (Moscow Meteorological Observatory in a large town and Toravere Actinometric Station in a rural area) allows us to point out the influence of a large town as a source of air pollution on the radiation transfer in the...
TL;DR: In this article, the influence of nine local, non-local and combined quantitative topographic characteristics on vegetation cover, altitude and density was studied in four areas of the Rudny Altai.
Abstract: We study the influence of nine local, non-local and combined quantitative topographic characteristics on vegetation cover, altitude and density. The objects under study are four areas of the Rudny Altai. Differentiation of plant properties is shown to depend on relief parameters which control migration and accumulation of water in landscape by gravity. These are landsurface curvatures, catchment area, topographic and stream power indexes. In some cases the phytocoenosis characteristics can have higher correlation with non-local and combined topographic variables than with local ones. This derives from the fact that non-local and combined relief attributes take into account a relative location of an area in a landscape, so they can better determine topographic prerequisites of substance motion. We demonstrate the advisability of the use of digital models and maps of indicated topographic characteristics in plant investigations.
TL;DR: An approach to the synthesis of a new class of liquid crystalline (LC) compounds, dendrimers of regular structure with terminal mesogenic groups, was elaborated in this article, based on the carbosilane dendritic matrix of first generation.
Abstract: An approach to the synthesis of a new class of liquid crystalline (LC) compounds, dendrimers of regular structure with terminal mesogenic groups, was elaborated. LC dendrimers based on the carbosilane dendritic matrix of first generation were synthesized. Cyanobiphenyl, methoxyphenyl benzoate and cholesteryl groups were used as mesogenic fragments. Individuality and structure of all compounds obtained was proved by GPC together with 1H- and 29Si NMR methods. The mesomorphic behaviour and structure of the LC dendrimers synthesized were investigated. It is argued that different mesophases of the smectic type are realized in all cases. It is shown that the mesophase type of these compounds essentially depends on the chemical nature of the mesogenic groups.
TL;DR: In this paper, it was shown that the collapse transition in weakly charged polyelectrolyte gels or single macromolecules can take place with an increase in the degree of ionization (e.g., during titration of a weak polyacid).
Abstract: Several experimental facts indicate that the collapse transition in weakly charged polyelectrolyte gels or single macromolecules can take place with an increase in the degree of ionization (e.g., during titration of a weak polyacid). This unusual behavior can be explained by the energy gain from the formation of ion pairs in the collapsed state of low polarity, which competes with the swollen state where most of the counterions are dissociated. An increasing degree of ionization increases the thermodynamic advantages of the collapsed state with an ionomeric multiplet structure over the swollen polyelectrolyte state. In some regimes, this effect can lead to reentrant phase transition behavior, i.e., to an initial decollapse of the gel upon charging with subsequent jumplike collapse at a higher fraction of charged monomer units.