Enhanced rise of rogue waves in slant wave groups

Numerical simulations of fully nonlinear equations of motion for long-crested waves at deep water demonstrate that in elongate wave groups the formation of extreme waves occurs most intensively if in an initial state the wave fronts are oriented obliquely to the direction of the group. An “optimal” angle, resulting in the highest rogue waves, depends on initial wave amplitude and group width, and it is about 18–28 degrees in a practically important range of parameters.     

Effect of temperature on the elastic anisotropy of pure Fe and Fe0.9Cr0.1 random alloy

The elastic properties of pure iron and substitutionally disordered 10 at.?% Cr Fe-Cr alloy are investigated as a function of temperature by using first-principles electronic-structure calculations by the exact muffin-tin orbitals method. The temperature effects on the elastic properties are included via the electronic, magnetic, and lattice expansion contributions. We show that the degree of magnetic order in both pure iron and Fe(90)Cr(10) alloy mainly determines the dramatic change of the elastic anisotropy of these materials at elevated temperatures. The effect of lattice expansion is found to be secondary but also very important for quantitative modeling.     

Isolation of Chitin from a Variety of Raw Materials, Modification of the Material, and Interaction its Derivatives with Metal Ions

At the Institute of Polymer Chemistry and Physics we have investigated the isolation of chitin from a variety of raw materials—of Aral Sea crustaceans, the basidial fungus Pleurotus ostreatus, and waste from production of natural silk from the chrysalis of the silkworm Bombyx mori. The silk worm chrysalis, waste material from silk production, is a very valuable and readily available source of chitin, although new technology must be developed to enable use of the waste. Other raw materials suitable for isolation of chitin are also being investigated. Other subjects of interest are modification of chitin, preparation of chitosan from it, and interaction of these materials with transition metals ions, because water-soluble polymer–metal complexes of known metal-ion content have medical and agricultural applications. Formation of complexes between chitosan and transition metal ions (Co, Ni, Cu, Mn) has been investigated. Differences between the spectra of chitosan and its metal complexes are all in the region of the stretching and deformation vibrations of the amide bonds (amide-I, amide-II, and amide-III). This is because the synthesis of chitosan–metal complexes was conducted in acid media, in which the chitosan amino group is protonated, so the preferred interaction takes place with the amide bond of chitosan. Noticeable changes of amide-I and amide-II intensities are observed, depending on the metal ion content; this changes can be used for estimation of the metal content in the samples. It has been shown that in the samples synthesized the metal ions are distributed fairly uniformly along the polymer chains. The composition and structures of the complexes formed, the conditions needed to include the different functional groups of the polymer in the coordination process, and the dynamics of macromolecular tangling behavior in the process of metal-ion binding were determined. This enables prediction of the behavior of chitosan–metal-ion systems under conditions of use.     

Longitudinal-transverse interaction in a three-dimensional boundary layer

Three-dimensional flow is considered for an incompressible fluid in a boundary layer developing along a curved solid surface during interaction between it and a small uneven area (projection or depression) on the surface. It is shown that an important part in the formation of the flow round the uneven area may be played by the drop in the pressure across the boundary layer. Conditions are formulated under which this effect, which is connected with the action of centrifugal forces, is realized. On the assumption that the longitudinal dimension of the uneven area is of the order of Re^–3/14, its width of the order of O(Re^–3/7), and its height O(Re^–4/7), where Re is the Reynolds number, asymptotic equations are derived which describe the motion of the fluid in the neighborhood of the uneven area.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 42–50, May–June, 1987.     

Morphometric model of lymphocyte as applied to scanning flow cytometry

The peripheral blood lymphocytes of normal individuals are investigated by methods of specialized light microscopy. Lymphocytes as a whole and T-cell subpopulation are considered. Lymphocyte structure is characterized with reference to polarizing scanning flow cytometry. The lymphocyte and lymphocyte nucleus shapes are analyzed. Linear correlation dependence between sizes of lymphocyte and its nucleus is indicated. A morphometric model of a lymphocyte is constructed using the obtained data. The findings can be used, for instance, as input parameters to solve the direct and inverse light-scattering problems of turbidimetry, nephelometry, and flow cytometry.     

Conformal variables in the numerical simulations of long-crested rogue waves

The recently suggested theoretical model for highly nonlinear potential long-crested water waves is discussed, where weak three-dimensional effects are included as small corrections to exact two-dimensional equations written in terms of the conformal variables [V.P. Ruban, Phys. Rev. E 71, 055303(R) (2005)]. Some numerical results based on this theory are presented, which describe spontaneous formation of rogue waves on the deep water for different initial conditions. In particular, the given numerical examples describe: (i) nonlinear stage of the modulational instability, (ii) breathing rogue wave in a random wave field, and (iii) freak wave in a weakly crossing sea state.