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Odessa, Ukraine

The Odessa I. I. Mechnikov National University , located in Odessa, Ukraine, is one of the country's major universities, named after the scientist Élie Metchnikoff , a Nobel prizewinner in 1908. The university was founded in 1865, by an edict of Tsar Alexander II of Russia reorganizing the Richelieu Lyceum of Odessa into the new Imperial Novorossiya University. In the Soviet era, the University was renamed Odessa I. I. Mechnikov National University .During the century and a half of its existence, the University has earned the reputation of being one of the best educational institutions in the Ukraine. The excellence of the University is also recognized outside the Ukraine; Odessa National University is one of the highest-ranked universities in the world, occupying 48th place in one rating of universities worldwide.Odessa I. I. Mechnikov National University comprises four institutes, ten faculties, and seven specialized councils. The University is famous for its scientific library, the largest and oldest of any university in the Ukraine . Wikipedia.

Chepizhko O.,Odessa I I Mechnikov National University | Chepizhko O.,University of Nice Sophia Antipolis | Peruani F.,University of Nice Sophia Antipolis
Physical Review Letters | Year: 2013

We study the transport properties of a system of active particles moving at constant speed in a heterogeneous two-dimensional space. The spatial heterogeneity is modeled by a random distribution of obstacles, which the active particles avoid. Obstacle avoidance is characterized by the particle turning speed γ. We show, through simulations and analytical calculations, that the mean square displacement of particles exhibits two regimes as function of the density of obstacles ρo and γ. We find that at low values of γ, particle motion is diffusive and characterized by a diffusion coefficient that displays a minimum at an intermediate obstacle density ρo. We observe that in high obstacle density regions and for large γ values, spontaneous trapping of active particles occurs. We show that such trapping leads to genuine subdiffusive motion of the active particles. We indicate how these findings can be used to fabricate a filter of active particles. © 2013 American Physical Society. Source

Kulinskii V.L.,Odessa I I Mechnikov National University
Journal of Chemical Physics | Year: 2010

The interpretation of the linear character of the observable classic rectilinear diameter law and the linear character of the Zeno-line (unit compressibility line Z=1) on the basis of global isomorphism between Ising model (lattice gas) and simple fluid is proposed. The correct definition of the limiting nontrivial Zeno state is given and its relation to the locus of the critical point is derived within this approach. We show that the liquid-vapor part of the phase diagram of the molecular fluids can be described as the isomorphic image of the phase diagram of the lattice gas. It is shown how the position of the critical points of the fluids of the Lennard-Jones type can be determined based on the scaling symmetry. As a sequence, the explanation of the well-known fact about "global" cubic character of the coexistence curve of the molecular fluids is proposed. © 2010 American Institute of Physics. Source

Kulinskii V.L.,Odessa I I Mechnikov National University
Journal of Chemical Physics | Year: 2010

We analyze the interrelation between the coexistence curve of the Lennard-Jones fluid and the Ising model in two and three dimensions within the global isomorphism approach proposed earlier [V. L. Kulinskii, J. Phys. Chem. B 114, 2852 (2010)]. In case of two dimensions, we use the exact Onsager result to construct the binodal of the corresponding Lennard-Jones fluid and compare it with the results of the simulations. In the three-dimensional case, we use available numerical results for the Ising model for the corresponding mapping. The possibility to observe the singularity of the binodal diameter is discussed. © 2010 American Institute of Physics. Source

Bekshaev A.Y.,Odessa I I Mechnikov National University
Central European Journal of Physics | Year: 2010

A ray-optics model is proposed to describe the vector beam transformation in a strongly focusing optical system. In contrast to usual approaches based on the focused field distribution near the focal plane, we use the beam pattern formed immediately after the exit aperture. In this cross section, details of the output field distribution are of minor physical interest but proper allowance is made for transformation of the beam polarization state. This enables the spin and orbital angular momentum representations to be obtained, which are valid for any cross section of the transformed beam. Simple analytical results are available for a transversely homogeneous, circularly polarized incident beam confined by a circular aperture. Variations of the spin and orbital angular momenta of the output beam with change of the focusing strength are analyzed. The analytical results are in good qualitative and reasonable quantitative agreement with the results of numerical calculations performed for the Gaussian and Laguerre-Gaussian beams. The model supplies an efficient and physically transparent means for qualitative analysis of the spin-to-orbital angular momentum conversion. It can be generalized to incident beams with complex spatial and polarization structure. © 2010 Versita Warsaw and Springer-Verlag Berlin Heidelberg. Source

Bekshaev A.Ya.,Odessa I I Mechnikov National University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

We analyze the paraxial beam transformation upon reflection and refraction at a plane boundary. In contrast to the usual approach dealing with the beam angular spectrum, we apply the continuity conditions to explicit spatial representations of the electric and magnetic fields on both sides of the boundary. It is shown that the polarization-dependent distortions of the beam trajectory (in particular, the "longitudinal" Goos-Hänchen shift and the "lateral" Imbert-Fedorov shift of the beam center of gravity) are directly connected to the incident beam longitudinal component and appear due to its transformation at the boundary. © 2012 American Physical Society. Source

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