Izvestiya of Saratov University.
ISSN 1817-3020 (Print)
ISSN 2542-193X (Online)


Физика

Identification of Action Potentials of Small Neuron Ensembles Using Wavelet-Analysis and Neural Networks Method

A possibility to solve the problem of automatic identification of neuronal spikes in the extracellularly recorded electrical potentials is discussed that is based on a combined approach assuming application of neural networks and the discrete wavelet-transform. Efficiency of the combined approach is illustrated in the analysis of experimental data.

About Conditionality of Nonlinear Responce of Miogenic Response of Afferent Arteriola for Irregular Self-Sustained Oscillations of Nephron Proximal Pressure

By means of nonlinear dynamics and time series analysis we investigate the possible mechanisms for the onset of chaotic selfsustained dynamics in nephron tubular pressure that is observed experimentally. Our results suggests that the miogenic constriction mechanism of afferent arteriola plays the key role providing the nonlinear response on temporal variation of filtration rate.

Cryptography from the Physicist's Point of View

The results of treating of crypto algorithms such as DES (USA) and GOST 28147-89 (Russia) with the help of nonlinear dynamics methods are presented. Point maps which are generated by the blocks of substitutions (S-blocks) are investigated. The phenomenon of return is demonstrated. The ergodicity of these maps are treated. An estimation of quality of S-block could be made by maps of first return. The results of statistical treating of S-biocks are presented.

Structure-Dinamic Modeles of Cyclopropane and Cyclopentene

Fashionable calculations of geometric and vibrational spectra of cyciopentane and cyclopentene are carried out. Nonplanar conformation for five-member cycle of molecule is cofirmed.

The Vibrationai Spectra of 2-Biphenylmethanol and their Interpretation by Using of Molecul Structural-Dynamical Model Taking into Account Mechanical Anharmonicity

Using hybrid density functional (B3LYP/6-31 (d)) the calculation of the geometry, electro-optical parameters, quartic force field and vibrational spectra of the 2-biphenylmethanol molecule were performed. The vibrational analysis was implemented and the full interpretation of its IR (400-3800 cm^(-1)) and Raman (50-3600 cm^(-1)) spectra was given.

IR Spectrum of the Methyl-β-D-Glucopyranoside and its Interpretation on Basis Structural-Dynamic Model Construction

Structural-dynamic models of the methyl-β-D-glucopyranoside molecule are constructed by density functional method in bases 6-31 G(d), 6-31+G (d, p). Energies, structures, dipole moments, polarizabilities, frequencies of normal modes in harmonic approximation and IR intensities have been calculated. Interpretation of IR absorption spectrum is presented in range 400-3700 cm^(-1). Advantages of model, which was constructed, compared with model, which bases on using valence-force field method and valency-optical theory, are discussed.

Ballistic Auto-Correlation Interferometry

We propose the implementation of a ballistic auto-correlation interferometer (BAI) for the assessment of biological tissues. We develop the theory of the interferometric technique, and demonstrate that a method to isolate ballistic from forward-scattered contributions is of central importance. We, therefore, propose theoretically and experimentally a non-linear grating-based angular filter. A monochromatic source incident on a ruled grating, positioned at grazing diffraction, is followed by a narrow slit to conform the proposed system.

The Investigation of the Fine Shift to the Energy Levels in the Hydrogen–Like Atoms with Accuracy α^6 ln α^(-1) by Quasipotential Method

In the quasipotential approach the quantity of Logarifmic corrections to the fine shift increased but the sum result of α^6 ln α^(-1) is equal zero. The past of high order to a corrections is calculated.

Prospects of Perfecting the Parameters Small-Dimensioned X-Band Microtron

In paper presented results of the calculation of microwave and magnetic systems X-band microtron. Microwave system is expected to run for the base monoblock monoblock magnetron-accelerating cavity. The results of the analysis of stationary processes and transients in such system are presented. The requirements to parameters of coupling element in of the magnetron's anode block with accelerating cavity are determined. The calculations of magnetic system for 5 MeV X-band microtron on the base permanent magnets are executed.

On the Problem of Complete Synchronization in Beam-Plasma Systems

Complete chaotic synchronization phenomenon in the unidirectionally coupled beam-plasma systems with overcritical current has been found. The boundary value of the synchronous regime onset in this case is shown to exceed the analogous value of the coupling parameter in the case of the mutual type of coupling in approximately two times.

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