Two dimensional modulational instability in photorefractive media

We study theoretically and experimentally the modulational instability of broad optical beams in photorefractive nonlinear media. We demonstrate the impact of the anisotropy of the nonlinearity on the growth rate of periodic perturbations. Our findings are confirmed by experimental measurements in a strontium barium niobate photorefractive crystal.Comment: 8 figure

Effects of oil extraction and recreational load on forest bird communities during the post-nesting period

Effects of recreational load and oil extraction on forest bird communities during the post-nesting period are considered in the article. Ornithocomplexes from recreation areas, places of oil extraction and ecosystems with lower anthropogenic press (Nizhnyaya Kama National Park, Republic of Tatarstan, Russia) were compared based on several indices. The lowest values of Shannon's index, Berger-Parker's index, species diversity, total density of population and maximum species density were observed in the forest bird communities of undisturbed areas. The highest values of the above-said indices were found in the forest areas, suffering from active recreation. The places of oil extraction occupy an intermediate position when their values for each of the indices are considered. The evenness index was highest for bird communities, inhabiting undisturbed areas. It was demonstrated that the effect of recreational load and oil extraction on forest ecosystems can be retraced from the basic indices calculated for bird communities during the post-nesting period. © IDOSI Publications, 2013

Modulational instability in nonlocal Kerr-type media with random parameters

Modulational instability of continuous waves in nonlocal focusing and defocusing Kerr media with stochastically varying diffraction (dispersion) and nonlinearity coefficients is studied both analytically and numerically. It is shown that nonlocality with the sign-definite Fourier images of the medium response functions suppresses considerably the growth rate peak and bandwidth of instability caused by stochasticity. Contrary, nonlocality can enhance modulational instability growth for a response function with negative-sign bands.Comment: 6 pages, 12 figures, revTeX, to appear in Phys. Rev.

Fusion in the entwined category of Yetter--Drinfeld modules of a rank-1 Nichols algebra

We rederive a popular nonsemisimple fusion algebra in the braided context, from a Nichols algebra. Together with the decomposition that we find for the product of simple Yetter-Drinfeld modules, this strongly suggests that the relevant Nichols algebra furnishes an equivalence with the triplet W-algebra in the (p,1) logarithmic models of conformal field theory. For this, the category of Yetter-Drinfeld modules is to be regarded as an \textit{entwined} category (the one with monodromy, but not with braiding).Comment: 36 pages, amsart++, times, xy. V3: references added, an unnecessary assumption removed, plus some minor change

Discrete instability in nonlinear lattices

The discrete multiscale analysis for boundary value problems in nonlinear discrete systems leads to a first order discrete modulational instability above a threshold amplitude for wave numbers beyond the zero of group velocity dispersion. Applied to the electrical lattice [Phys. Rev. E, 51 (1995) 6127 ], this acurately explains the experimental instability at wave numbers beyond 1.25 . The theory is also briefly discussed for sine-Gordon and Toda lattices.Comment: 1 figure, revtex, published: Phys. Rev. Lett. 83 (1999) 232

Pattern generation by dissipative parametric instability

Nonlinear instabilities are responsible for spontaneous pattern formation in a vast number of natural and engineered systems, ranging from biology to galaxy buildup. We propose a new instability mechanism leading to pattern formation in spatially extended nonlinear systems, which is based on a periodic antiphase modulation of spectrally dependent losses arranged in a zigzag way: an effective filtering is imposed at symmetrically located wave numbers k and -k in alternating order. The properties of the dissipative parametric instability differ from the features of both key classical concepts of modulation instabilities, i.e., the Benjamin-Feir instability and the Faraday instabiltyity. We demonstrate how the dissipative parametric instability can lead to the formation of stable patterns in one- and two-dimensional systems. The proposed instability mechanism is generic and can naturally occur or can be implemented in various physical systems

Comparison of liquid chromatography-mass spectrometry and direct infusion microchip electrospray ionization mass spectrometry in global metabolomics of cell samples

In this study, the feasibility of direct infusion electrospray ionization microchip mass spectrometry (chip-MS) was compared to the commonly used liquid chromatography-mass spectrometry (LC-MS) in non-targeted metabolomics analysis of human foreskin fibroblasts (HFF) and human induced pluripotent stem cells (hiPSC) reprogrammed from HFF. The total number of the detected features with chip-MS and LC-MS were 619 and 1959, respectively. Approximately 25% of detected features showed statistically significant changes between the cell lines with both analytical methods. The results show that chip-MS is a rapid and simple method that allows high sample throughput from small sample volumes and can detect the main metabolites and classify cells based on their metabolic profiles. However, the selectivity of chip-MS is limited compared to LC-MS and chip-MS may suffer from ion suppression.Peer reviewe

Fibrocystic disease and breast cancer risk (а review of literature)

The article discusses the relationship between etiology and risk factors of fibrocystic disease (FCD) and breast cancer (BC), pathogenesis of FCD in connection with increasing risk of BC, assessment of BC risk in patients with FCD; pathogenetic treatment of FCD aimed for preventing BC; the use of the drug progestogel for the treatment of FCD and prevention of BC. FCD and BC have general etiology and the most risk factors are identical for the both pathologies. Multiple risk factors disturb hormonal balance in the organism of a woman, cause hyperestrogenism and epithelium hyperproliferation in the mammary tissue that results in the development of FCD and at presenceof congenital or acquired gene damage results in the development of BC. Decision value for the estimation of degree of a BC risk in patients with FCD has morphological research of mammary tissue got at a biopsy. The risk of developing BC for non-proliferative FCD does not rise or is minimal. Proliferative FCD without atypia or with atypia was associated with significantly increased BC risk in 2 or 4 times, correspondingly. The risk of developing BC for FCD with ductal or lobular carcinoma in situ is maximal and may be increased in 12 times. Progestogel is hormonal medicinal drug containing progesterone for local application. Results of undertaken studies and supervisions allow to conclude that progestogel is not only effective and safe drug for pathogenetic treatment of FCD and thus could be regarded as indirect factor to decrease BC risk

Investigation of interaction femtosecond laser pulses with skin and eyes mathematical model

We present a mathematical model of linear and nonlinear processes that takes place under the action of femtosecond laser radiation on the cutaneous covering. The study is carried out and the analytical solution of the set of equations describing the dynamics of the electron and atomic subsystems and investigated the processes of linear and nonlinear interaction of femtosecond laser pulses in the vitreous of the human eye, revealed the dependence of the pulse duration on the retina of the duration of the input pulse and found the value of the radiation power density, in which there is a self-focusing is obtained. The results of the work can be used to determine the maximum acceptable energy, generated by femtosecond laser systems, and to develop Russian laser safety standards for femtosecond laser systems

Modulational instability and nonlocality management in coupled NLS system

The modulational instability of two interacting waves in a nonlocal Kerr-type medium is considered analytically and numerically. For a generic choice of wave amplitudes, we give a complete description of stable/unstable regimes for zero group-velocity mismatch. It is shown that nonlocality suppresses considerably the growth rate and bandwidth of instability. For nonzero group-velocity mismatch we perform a geometrical analysis of a nonlocality management which can provide stability of waves otherwise unstable in a local medium.Comment: 15 pages, 12 figures, to be published in Physica Script