Faculty of Physics
M.V.Lomonosov Moscow State University
Physics of Earth, atmosphere, and hydrosphere

## Numerical tsunami modelling and the bottom relief

### E.A. Kulikov, V.K. Gusiakov, A.A. Ivanova, B.V. Baranov

Moscow University Physics Bulletin 2016. 71. N 6. P. 527

This work deals with effect of the bathymetry data quality on accuracy of the tsunami wave field calculations. It demonstrates that current digital bathymetry maps (i.e. GEBCO) do not ensure adequate accuracy in reproducing the bottom topography for numerical modeling of wave propagation which can result in significant errors in assessment of tsunami runup at the coast.

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## About influence of electrons velocities spread in the beam on the mechanism of Cherenkov beam-plasma interaction

### I.N. Kartashov, M.V. Kuzelev

Moscow University Physics Bulletin 2016. 71. N 6. P. 537

In linear potential approach instability of an electron beam in cold plasma for various distribution functions of electrons of a beam on velocities is considered. It is shown that at increase in spread of electrons of a beam on velocities there is a transformation of the mechanism of beam instability in plasma: the hydrodynamic one-particle mode of instability transforms into the hydrodynamic collective mode, or into the one-particle kinetic mode. Analytically and numerically instability growth rates in various modes are defined.

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Condensed matter physics

## Effects 2D-dissipative tunneling system combined AFM/STM

### V.Ch. Zhukovsky$^1$, V.D. Krevchik$^2$, M.B. Semenov$^2$, P.V. Krevchik$^2$, R.V. Zaitsev$^2$, I.A. Egorov$^2$

Moscow University Physics Bulletin 2016. 71. N 6. P. 545

In frames of the one-instanton approximation the field and temperature dependence of the 2D - dissipative tunneling probability for the model double-oscillator potential in the conditions of an external electric field at a finite temperature with the influence of two local phonon modes for the quantum dots in the system of combined atomic force / scanning tunneling microscope, have been theoretically investigated. It is shown that in synchronous mode, the parallel transfer of tunneling particles from the cantilever tip to a quantum dot with account of the two local phonon modes influence leads to appearance of two stable peaks on the field dependence of the 2D - dissipative tunneling probability. A qualitative comparison of the theoretical curve in the limit of weak dissipation with the experimental tunneling current-voltage characteristics for growing quantum dots of colloidal gold under the cantilever tip at the initial stage of the quantum dot formation, when the size of quantum dots does not exceed 10 nm, has been fulfilled. It was found that on the temperature dependence of the 2D- dissipative tunneling probability one of two stable peaks, corresponding to interaction of the tunneling particle with two local phonon modes, can be splitted into two peaks, which is associated with mechanism of the tunneling channels interference. It has been found, that near the bifurcation point the theoretically predicted and experimentally observed a quantum-beat mode, can be realized.

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Biophysics and medical physics

## Slow variations of electroconductivity of distilled water

### I.M. Ageev, Yu.M. Rybin, G.G. Shishkin

Moscow University Physics Bulletin 2016. 71. N 6. P. 556

Experimental studies on the measurement of the conductivity of distilled water in a slowly changing its temperature were performed. We detected periodic variations in the electrical conductivity of the water, in observed rate of change of the temperature $dT/dt<0.1$ K/h. Period is more than a day, variations in the amplitude range from + 2.7% to - 2.3%. Possible reasons for the observed phenomena is discussed.

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## Autowave self-organization in heterogeneity naturally-anthropogenic ecosystems

### A.E. Sidorova, N.T. Levashova, A.A. Melnikova, N.N. Deryugina, A.E. Semina

Moscow University Physics Bulletin 2016. 71. N 6. P. 562

The article considers the spatio-temporal model of natural and man-made ecosystems, such as conjugated active media, taking into account the heterogeneity of anthropogenic and natural factors. The approach aims to identify the threshold values of the control parameters. The theoretical basis of the system analysis of the sustainability of ecosystems are synergistic idea of auto-wave of self-organization in active media. The mathematical model is based on a modified system of Fitz-Hugh-Nagumo equations.

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