Search Results - (Author, Cooperation:A. Frolov)

2013-03-23

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Biocatalysis ; Dynamin I/*chemistry/*metabolism ; Guanosine Triphosphate/metabolism ; Hydrolysis ; Lipid Bilayers/chemistry/*metabolism ; Models, Biological ; Nanotubes ; Protein Conformation ; Protein Multimerization ; Protein Structure, Tertiary ; Thermodynamics

2018-12-02

Institute of Physics (IOP)

1757-8981

1757-899X

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

2012-12-04

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Animals ; COUP Transcription Factor II/deficiency/genetics/*metabolism ; Cell Cycle Checkpoints ; Cell Line, Tumor ; *Cell Transformation, Neoplastic ; Disease Models, Animal ; Disease Progression ; Gene Deletion ; Humans ; Male ; Mice ; Neoplasm Metastasis ; PTEN Phosphohydrolase/deficiency/genetics ; Proportional Hazards Models ; Prostate/metabolism/pathology ; Prostatic Neoplasms/*metabolism/*pathology ; *Signal Transduction ; Smad4 Protein/deficiency/genetics/metabolism ; Transforming Growth Factor beta/*antagonists & inhibitors/metabolism

2015-07-01

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

2014-10-31

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Animals ; Biological Transport ; CHO Cells ; Cell Membrane/*chemistry/*metabolism ; Cell Survival ; Cricetulus ; DNA/metabolism ; HEK293 Cells ; Humans ; Ion Channels/metabolism ; Lipid Bilayers/*chemistry/*metabolism ; Liposomes ; *Nanotubes, Carbon/ultrastructure ; Porins/chemistry/*metabolism ; *Stochastic Processes

article

1985

Bildungstheorie ; Biografie ; Makarenko, Anton Semjonowitsch

Vergleichende Pädagogik, Bd. 21 (1985) H. 2, S. 150-156, 0042-3920

0505-3072

facet.language.fre, facet.language.ger, facet.language.eng, facet.language.rus

Literaturangaben

article

2002

Erziehung ; Historische Pädagogik ; Erziehungsmittel ; Bildungsgeschichte ; Schule ; Lebensnähe ; Russland

Pedagogika (Moskau), (2002) H. 6, S. 71-77, 0869-561X

Russian

Literaturangaben 7

2018-12-11

The Company of Biologists

0950-1991

1477-9129

Biology

1089-7666

AIP Digital Archive

Physics

It is demonstrated that the magnetization current, which arises from the interaction of high-frequency electromagnetic waves with hot collisionless, unmagnetized electron plasmas, can be derived by means of the ten-moment system of hydrodynamic equations. It is pointed out that the magnetization current is solely associated with the thermal motion of the electrons, and that it therefore does not appear in cold plasmas. This expression for the magnetization current agrees with those derived previously from kinetic theory. The present derivation provides, however, a comparatively much clearer physical picture of the origin of this current. In the limit where the phase velocity is much larger than the electron thermal velocity, a new result for the high-frequency induced vorticity of the plasma is obtained. It is also shown that the magnetization current in this paper is responsible for a novel scattering mechanism in which the high-frequency electromagnetic waves are scattered off vortex motions.

Electronic Resource

1570-1468

Springer Online Journal Archives 1860-2000

Energy, Environment Protection, Nuclear Power Engineering

Conclusions 1. More effective storage of industrial wastes and clarification of water is realized on hydraulic-fill dumps of the thermally loaded type, and at the same time subsequent excavation of these dumps for using the wastes in the economy is facilitated. 2. Since the estimates obtained characterizing the thermal regime of the structure take into account the relationship between the incoming and dissipated heat regardless of the type of solid phase and its consistency, by means of the developed classification it is possible to substantiate the construction not only of dumps but also, by using various measures to maintain a thermally loaded state, hydraulic-fill structures in various climatic regions of the Soviet Union with consideration, of course, of the differences in the specific heat of the materials being placed.

Electronic Resource

1570-1468

Springer Online Journal Archives 1860-2000

Energy, Environment Protection, Nuclear Power Engineering

Conclusions 1. Treatment of the surfaces of construction joints is an expensive operation whose performance requires additional work by the concrete-placing equipment, which to some extent adversely affects the rate of concreting. 2. In recent years the surfaces of construction joints at foreign hydroprojects in the majority of cases have been treated by high-pressure (280–420 kg/cm2) water-air jets. Comparatively recently special concrete-setting retarders began to be used on foreign construction projects, thanks to which the time during which the concrete surfaces can be treated effectively by water-air jets is increased. 3. The spreading and brushing of a thin layer of sand-cement mortar onto the surface of horizontal construction joints for a long time was standard practice abroad in preparing the joints before placing the concrete in the next blocks. Investigations conducted in recent years did not confirm the superiority of a joint with an underlying layer of mortar with respect to cohesion and density over a joint on which the sand-cement mortar was not placed. In connection with this many design organizations in a number of countries and particularly in the U.S.A. do not include the placement of an underlying layer in the concreting technical specifications. This saves cement (about 2%) and reduces labor costs for preparing the blocks for concreting and increases the efficiency of concrete plants and concrete-placing equipment.

Electronic Resource

1432-5411

Springer Online Journal Archives 1860-2000

Physics

Abstract The best variational energies obtained to date for the ground states of all μ-mesomolecules are presented. The results are of rather high accuracy and can serve as a theoretical basis for the experimental study of three-body systems. The energies of thee − e + e −,∞H− and 11 S, 23 S, 23 P, 23 P states of∞He are calculated using the same method.

Electronic Resource

1090-6487

76.60.Lz ; 75.25.+z.466

Springer Online Journal Archives 1860-2000

Physics

Abstract The 57 Fe spin echo spectra were studied in local magnetic fields of a BiFeO3 ferroelectric antiferromagnet over the temperature range 77–304 K. The line shape analysis confirmed the presence of a spatially modulated, incommensurate cycloidal spin structure in BiFeO3 and allowed the actual spin distribution to be reproduced throughout the cycloid length. The distribution was found to be essentially anharmonic. The modulated structure is stable over the whole temperature range studied. The cycloid wave becomes more harmonic with temperature elevation.

Electronic Resource

1432-1106

Motor cortex ; Conditioned movement ; Posture ; Balance control ; Cat

Springer Online Journal Archives 1860-2000

Medicine

Summary The role of the sensorimotor cortex in the postural adjustments associated with conditioned paw lifting movements was investigated in the cat. Cats were trained to stand quietly on four strain gauge equipped platforms and to perform a lift-off movement with one forelimb when a conditioned tone was presented. The parameters recorded were the vertical forces exerted by the paws on each platform, the lateral and antero-posterior displacements of rods implanted on the T2, T12, L5 vertebrae as well as their rotation, and the EMG of triceps and biceps of both forelimbs. Before lesion, the postural adjustment consisted of a “nondiagonal” pattern where the CG was displaced laterally inside the triangle formed by the three remaining supporting limbs. Here a lateral bending of the thoracic column toward the supporting forelimb could be observed. The associated EMG pattern consisted of an early activation of the triceps lateral head in the moving limb which was probably responsible for the body displacement toward the opposite side, and a late biceps activation associated with the lift. In the supporting forelimb, a coactivation of the biceps and triceps was usually present. After contralateral sensorimotor lesion, the conditioned lifting movements were lost for 4–15 days after the lesion, before being subsequently recovered. The same lateral CG displacement and bending of the back was seen after lesion as before, which indicates that the goal of postural adjustment was preserved. However, the means of reaching it were modified. In most of the intact animals, the CG displacement was achieved in one step, whereas in the animals with lesions, the displacement was made either according to a slow ramp mode or in a discontinuous manner involving several steps. The mechanisms responsible for this disturbance are discussed.

Electronic Resource

1432-1106

Key words Posture maintenance ; Bimanual unloading ; Joint stiffness ; Equilibrium angle ; Invariant characteristics

Springer Online Journal Archives 1860-2000

Medicine

Abstract  In this study, the equilibrium-point hypothesis of muscle-torque generation is used to evaluate the changes in central control parameters in the process of postural-maintenance learning. Muscle torque is described by a linear spring equation with modifiable stiffness, viscosity, and equilibrium angle. The stiffness is considered to be the estimation of the central command for antagonist-muscle coactivation and the equilibrium angle to be the estimation of the reciprocal command for a shift of invariant characteristics of the joint. In the experiments, a load applied to the forearm was released. The subjects were instructed to maintain their forearm in the initial horizontal position. Five sessions of approximately twenty trials each were carried out by eight subjects. During two ”control” series, the load release was triggered by the experimenter. During three ”learning” series, the load supported by one forearm was released by the subject’s other hand. The elbow-joint angle, the angular acceleration, and the external load on the postural forearm were recorded. These recordings as well as anthropometric forearm characteristics were used to calculate the elbow-joint torque (which we called ”experimental”). Linear regression analysis was performed to evaluate the equilibrium angle, joint stiffness, and viscosity at each trial. The ”theoretical” torque was calculated using a linear spring equation with the found parameters. The good agreement observed between experimental and theoretical joint-torque time courses, apart from the very early period following unloading, argues in favor of the idea that the movement was mainly performed under a constant central command presetting the joint stiffness and the equilibrium angle. An overall increase in the stiffness occurred simultaneously with a decrease in the equilibrium angle during the ”learning” series in all the subjects. This suggests that subjects learn to compensate for the disturbing effects of unloading by increasing the joint stiffness. The mechanism possibly responsible for the presetting of the central control parameters is discussed.

Electronic Resource

1432-0770

Springer Online Journal Archives 1860-2000

Biology

Computer Science

Physics

Abstract. It has been widely claimed that linear models of the neuromuscular apparatus give very inaccurate approximations of human arm reaching movements. The present paper examines this claim by quantifying the contributions of the various non-linear effects of muscle force generation on the accuracy of linear approximation. We performed computer simulations of a model of a two-joint arm with six monarticular and biarticular muscles. The global actions of individual muscles resulted in a linear dependence of the joint torques on the joint angles and angular velocities, despite the great non-linearity of the muscle properties. The effect of time delay in force generation is much more important for model accuracy than all the non-linear effects, while ignoring this time delay in linear approximation results in large errors. Thus, the viscosity coefficients are rather underestimated and some of them can even be paradoxically estimated to be negative. Similarly, our computation showed that ignoring the time delay resulted in large errors in the estimation of the hand equilibrium trajectory. This could explain why experimentally estimated hand equilibrium trajectories may be complex, even during a simple reaching movement. The hand equilibrium trajectory estimated by a linear model becomes simple when the time delay is taken into account, and it is close to that actually used in the non-linear model. The results therefore provide a theoretical basis for estimating the hand equilibrium trajectory during arm reaching movements and hence for estimating the time course of the motor control signals associated with this trajectory, as set out in the equilibrium point hypothesis.

Electronic Resource

1090-6525

Springer Online Journal Archives 1860-2000

Physics

Abstract Planar n-p-n transistors are fabricated with various profiles of the base impurity distribution, and their electrical parameters are investigated. An equation for calculating the breakdown voltage of the collector-base junction is proposed on the basis of an experimental data analysis. It is shown that the use of a planar p-n junction raises the collector junction breakdown voltages of planar n-p-n transistors.

Electronic Resource

1090-6525

Springer Online Journal Archives 1860-2000

Physics

Electronic Resource

1573-9171

free-radical reactions ; carbohydrates ; chiral cyclopentanes

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Abstract The decisive influence of the carboxyl group on the methanolysis of 3-methoxy-4-methoxycarbonylmethyl-2-oxabicyclo[2.2.1.]heptanes was proved experimentally, and several routes of conversion of the latter to the corresponding cyclopentanes were found.

Electronic Resource

1573-9171

free radical reactions ; carbohydrates ; chiral cyclopentanes ; chiral tetrahydrofurans

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Abstract The benzyloxy group at C(4) of the pyranose ring in 3,4-disubstituted and 3-deoxy carbohydrate derivatives affects the direction of intramolecular free-radical C(2)-C(6) cyclization. A possible mechanism of the formation of the tetrahydrofuran ring was proposed.

Electronic Resource