Nonlinear problems of complex natural systems: Sun and climate dynamics.

The universal role of the nonlinear one-third subharmonic resonance mechanism in generation of strong fluctuations in complex natural dynamical systems related to global climate is discussed using wavelet regression detrended data. The role of the oceanic Rossby waves in the year-scale global temperature fluctuations and the nonlinear resonance contribution to the El Niño phenomenon have been discussed in detail. The large fluctuations in the reconstructed temperature on millennial time scales (Antarctic ice core data for the past 400,000 years) are also shown to be dominated by the one-third subharmonic resonance, presumably related to the Earth's precession effect on the energy that the intertropical regions receive from the Sun.

Chaos from turbulence: stochastic-chaotic equilibrium in turbulent convection at high Rayleigh numbers.

It is shown that the correlation function of the mean wind velocity generated by a turbulent thermal convection (Rayleigh number Ra ∼ 10(11)) exhibits exponential decay with a very long correlation time, while the corresponding largest Lyapunov exponent is certainly positive. These results together with the reconstructed phase portrait indicate the possible presence of chaotic component in the examined mean wind. Telegraph approximation is also used to study the relative contribution of the chaotic and stochastic components to the mean wind fluctuations and an equilibrium between these components has been studied in detail.

Fluctuations of temperature gradients in turbulent thermal convection.

Broad theoretical arguments are proposed to show, formally, that the magnitude G of the temperature gradients in turbulent thermal convection at high Rayleigh numbers obeys the same advection-diffusion equation that governs the temperature fluctuation T , except that the velocity field in the new equation is substantially smoothed. This smoothed field leads to a -1 scaling of the spectrum of G in the same range of scales for which the spectral exponent of T lies between -7/5 and -5/3 . This result is confirmed by measurements in a confined container with cryogenic helium gas as the working fluid for Rayleigh number Ra=1.

Intermittency and the passive nature of the magnitude of the magnetic field.

It is shown that the statistical properties of the magnitude of the magnetic field in turbulent electrically conducting media resemble, in the inertial range, those of passive scalars in fully developed three-dimensional fluid turbulence. This conclusion, suggested by the data from the Advanced Composition Explorer, is supported by a brief analysis of the appropriate magnetohydrodynamic equations.

"Clusterization" and intermittency of temperature fluctuations in turbulent convection.

Temperature time traces are obtained in turbulent thermal convection at high Rayleigh numbers. Measurements are made in the midplane of the apparatus, near the sidewall but outside the boundary layer. A telegraph approximation for temperature traces is generated by setting the fluctuation amplitude to 1 or 0 depending on whether or not it exceeds the mean value.

Multiscaling of galactic cosmic ray flux.

Multiscaling analysis of the differential flux dissipation rate of galactic cosmic rays (carbon nuclei) is performed in the energy ranges 56.3-73.4 MeV/nucleon and 183.

Anomalous three-dimensional symmetries of solar-wind plasma.

An example of a combination of Kolmogorov three-dimensional properties with Alfvén two-dimensional properties in solar-wind plasma is given using recent data obtained with the Advanced Composition Explorer satellite at the L1 libration point. Both spectral and moments scaling analyses are used to demonstrate the possibility of such a combination. Two-decade scaling and the large number of the scaling exponents under consideration indicate the robustness of this observation.

Mean wind and its reversal in thermal convection.

Properties of the mean wind in thermal convection, especially the abrupt reversal of its direction at high Rayleigh numbers, are studied. Measurements made in a closed cylindrical container of aspect ratio 1 are analyzed, and both the long-term and short-term behaviors of the direction reversals are discussed. A first look at the data suggests a Brownian-type process in action, but a closer look suggests the existence of hierarchical features with time scales extending roughly over a decade and a half.

Some properties of multifractality at solid-on-solid growth processes.

It is shown that multifractality of large deposition probabilities observed in a simple model of crystal growth (the Das Sarma model with neglected surface diffusion, desorption, and hop) corresponds to another type of statistical distribution: multifractal Bernoulli distribution. Lognormal distribution is also discussed in this context.

Probabilistic properties of wavelets in kinetic surface roughening.

Using the data of a recent numerical simulation [M. Ahr and M. Biehl, Phys.

Local properties of extended self-similarity in three-dimensional turbulence.

Using a generalization of extended self-similarity we have studied local scaling properties of incompressible homogeneous isotropic three-dimensional turbulence in a direct numerical simulation. We have found that these properties are consistent with log-normal-like behavior of the velocity increments with moderate amplitudes for space scales r beginning from Kolmogorov length eta up to the largest scales, and in the whole range of the Reynolds numbers: 50 < or = R(lambda) < or = 459. The locally determined intermittency exponent mu(r) varies with r; it has a maximum at scale r=14 eta, independent of R(lambda).

[Changes in the organization of the intermediate filament system of human fibroblasts in lysosomal storage diseases and their modeling].

The organization of the system of the vimentin intermediate filaments (IFs) in human fibroblasts in lysosomal storage diseases (Fabry's disease, mannosidosis) and their modelling has been studied in vitro. It was shown that during accumulation of nonhydrolyzable compounds, hypertrophy of the lysosomal compartment is accompanied by formation of ring-shaped bundles IFs, surrounding apparently these increased organelles. The changed organization of IFs is characteristic of polarised pathological cells in monolayer, and after repassage it is retained only at the spreading state; on transition from the discoid to extended cellular form there occurred the centrifugal shift of ring-shaped structures of IFs to active cell border and gradual restoration of radial fibrillar state of IFs.

[The role of intermediate filaments in forming cellular processes induced in fibroblasts by the tumor promoter TPA].

A tumor promoter phorbol 12-myristate 13-acetate (PMA) induces characteristic reversible changes in the cell shape in certain fibroblastic lines. This reaction to PMA may be regarded as a prototype of reorganizations involving formation of stable cytoplasmic processes. Two specific drugs, Taxol and Colcemid, were used to study the role of microtubules and vimentin-containing intermediate filaments (IF) in the development of PMA-induced reorganizations.

[The normalization of tumor cell morphology related to an increase in their size: research on giant cells produced by mitomycin C treatment].

This study shows that artificial increase in cell site leads to morphological normalization of transformed fibroblasts. Mouse L cells (clone 171/5) were used. As most transformed cells, they were poorly spread on the substratum, made only dot-like focal contacts with it, rounded quickly at room temperature and did not contain prominent actin cables.

[Normalization of the phenotype of transformed Djungarian hamster cells during selection for colchicine resistance].

The range of the Djungarian hamster cell lines selected for colchicine resistance in high doses (from 7 to 200 micrograms/ml) was studied. These cell lines are characterized by the different levels of drug-resistance (1000- to 16000-fold). A positive correlation is found between the reversion rate of malignant phenotype and the cellular drug-resistance level.

[Formation of an actin cytoskeleton and adhesive structures during the spreading of cultured cells].

Fibroblast spreading was studied using immunofluorescent method that provided visualization of actin structures and adhesion contacts in the same cell. Four stages of actin system formation were observed. 1.

[Focal contacts and the cytoskeleton].

Cultured cells attach to the substratum by means of specialized domains of cell surface, called focal contacts. The inner side of the cell membrane is associated in these structures with cytoskeletal elements, while the outer side is connected with extracellular matrix. The present review describes both light and electron microscopic methods of studying the focal contacts and ultrastructure of adhesion plaque, that is the cytoskeletal domain of focal contact.

[Relation between the attachment of cells to a substrate and their proliferative characteristics].

17 cloned cell lines of transformed mouse fibroblasts were used for the evaluation of a correlation between three traits of malignancy: cloning efficiency in semisolid medium (CE); cell dose inducing tumours in 50% of inoculated animals (TD50); degree of cell attachment to a substrate (RT50--rounding time for 50% of the cells under moderate cooling, 18 degrees C). It is shown that an increase in RT50 (better attachment of the cells to the substrate) is accompanied by a decrease in CE and an increase in TD50 (coefficients of rank correlation p = -0.76 and p = 0.

[Structure of the cytoskeleton of embryonic muscle fibroblasts. Electron microscopic study of platinum replicas].

Cultured mouse embryo fibroblasts were extracted with 1% Triton X-100 at pH 6.7 in buffer containing EGTA and stabilizing supplements. Exposed during this extraction cytoskeletons were fixed, dried with the critical point technique, and shadowed with platinum.

[Cell rounding in variant sublines of the L line caused by a moderate decrease in temperature].

Several novel variants of mouse transformed L cells are described. A distinctive trait of these variants, isolated by different methods, is a rounding of the majority of cells under the influence of the moderate cooling (at 18 degrees C for 30-60 min). In the serum-free medium, no rounding occurs.

[Morphology of the microtubule system in mouse kidney epithelial cells].

The cultured mouse kidney cells forming epithelial sheets were studied using an indirect immunofluorescence microscopy with antibodies against tubulin. These cells, as well as fibroblasts, were found to contain a well developed microtubular system sensitive to colcemid. The assembly of microtubules after washing out of colcemid began from one or two perinuclear centers, associated with the cilium-like structure.