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

Nonlinear photonic lattices in anisotropic nonlocal self-focusing media

We analyze theoretically and generate experimentally two-dimensional nonlinear periodic lattices in a photorefractive medium. We demonstrate that the light-induced periodically modulated nonlinear refractive index is highly anisotropic and nonlocal, and it depends on the lattice orientation relative to the crystal axis. We discuss stability of such induced photonic structures and their guiding properties.Comment: 3 pages, 3 figure

Induced Coherence and Stable Soliton Spiraling

We develop a theory of soliton spiraling in a bulk nonlinear medium and reveal a new physical mechanism: periodic power exchange via induced coherence, which can lead to stable spiraling and the formation of dynamical two-soliton states. Our theory not only explains earlier observations, but provides a number of predictions which are also verified experimentally. Finally, we show theoretically and experimentally that soliton spiraling can be controled by the degree of mutual initial coherence.Comment: 4 pages, 5 figure

Innate and acquired immunity indices in assessing the clinical severity of patients with childhood schizophrenia

The results of previous studies suggest pathogenetic role of immune system in the development of schizophrenia. Examination of adolescent and young adult schizophrenic patients showed that the activity/ level of distinct parameters of innate and acquired immunity correlates with acuity and severity of pathological process in the brain. Presumably, evaluation of immune system characteristics in patients with childhood schizophrenia, concerning severity of their clinical symptoms, along with potential therapeutic aspect, may be the basis for early diagnosis of these conditions, and monitoring and prognosis of the further progression of the disease. The objective of our study was to compare clinical and immunological indices in children with schizophrenia to analyze the possibility of using these parameters for determination of the degree of activity of the pathological process. Sixty-two patients (39 boys and 23 girls) from 4 to 17 years of age with childhood schizophrenia were examined. Psychopathological and psychometric methods (PANSS and CGI-S scales) were used to assess mental state of the patients. Immunological parameters were determined in blood serum taken by fingerprick. Activity of leukocyte elastase (LE) and a1-proteinase inhibitor (a1-PI) was determined by spectrophotometric method. To determine the level of autoantibodies to S-100B and MBP, we used enzyme immunoassay. The study revealed activation of innate (by activity of LE and a1-PI) and acquired (by the level of autoantibodies to S-100B and MBP neuroantigens) immunity markers in blood serum of children with schizophrenia. Correlation analysis showed the significant positive correlation between complex evaluation of activation level of the immune system and severity of the patients’ state on the CGI-S scale (r = 0.64, p < 0.0001), as well as severity of negative symptoms according to the PANSS scale (r = 0.34, p = 0.0077). The revealed correlations suggest an opportunity for using immunological parameters (LE and a1-PI activity, and antibodies to neuroantigens), as the additional laboratory criteria for the assessment of clinical state in patients with childhood schizophrenia

Observation of dipole-mode vector solitons

We report on the first experimental observation of a novel type of optical vector soliton, a {\em dipole-mode soliton}, recently predicted theoretically. We show that these vector solitons can be generated in a photorefractive medium employing two different processes: a phase imprinting, and a symmetry-breaking instability of a vortex-mode vector soliton. The experimental results display remarkable agreement with the theory, and confirm the robust nature of these radially asymmetric two-component solitary waves.Comment: 4 pages, 8 figures; pictures in the PRL version are better qualit

Constrictive pericarditis in a patient with inherited factor VII deficiency

Constrictive pericarditis (CP) is the final stage of a chronic inflammatory process characterized by fibrous thickening and calcification of the pericardium that impairs diastolic filling, reduces cardiac output, and ultimately leads to heart failure. We present a clinical case of CP in a patient with rare inherited bleeding disorder - factor VII deficiency. Heart failure due to CP was suspected based on clinical symptoms, results of ultrasonic and radiological investigations. The diagnosis was verified by the results of cardiac magnetic resonance imaging. Pericardectomy was performed resulting in significant improvement in the patient’s condition

Literature review and clinical observation of acquired idiopathic hemophilia with a new missense mutation in the factor VIII gene (His2026Arg)

The article provides review of possible mechanisms of inhibitor coagulopathies, in particular of acquired hemophilia A. This pathology is an extremely rare disease occurring in 1-2 cases in 1 million per year. In the present study we provide data for two clinical cases of hemophilia A in women. These cases had different development mechanisms, although both women have a newly discovered missense mutation His2026Arg in the VIII factor gene. The matter of main interest is the description of the disease development in the patient with an acquired idiopathic hemophilia A with a possible disease occurrence due to an asymmetric X-chromosome inactivation (lyonization). In this particular case lyonization led to the late manifestation of the hemophilia A carrier’s state and development of severe form of the inhibitor-associated acquired hemophilia A. We also discuss therapeutic approaches to these forms of the disease, considering there are no concise protocols for case management due to an extreme rarity of the pathology. Acquainting the clinical personnel working it the different areas of medicine with suchlike inhibitor coagulopathies has a major practical importance

Modulational instability of bright solitary waves in incoherently coupled nonlinear Schr\"odinger equations

We present a detailed analysis of the modulational instability (MI) of ground-state bright solitary solutions of two incoherently coupled nonlinear Schr\"odinger equations. Varying the relative strength of cross-phase and self-phase effects we show existence and origin of four branches of MI of the two-wave solitary solutions. We give a physical interpretation of our results in terms of the group velocity dispersion (GVD) induced polarization dynamics of spatial solitary waves. In particular, we show that in media with normal GVD spatial symmetry breaking changes to polarization symmetry breaking when the relative strength of the cross-phase modulation exceeds a certain threshold value. The analytical and numerical stability analyses are fully supported by an extensive series of numerical simulations of the full model.Comment: Physical Review E, July, 199

On the Properties of Two Pulses Propagating Simultaneously in Different Dispersion Regimes in a Nonlinear Planar Waveguide

Properties of two pulses propagating simultaneously in different dispersion regimes, anomalous and normal, in a Kerr-type planar waveguide are studied in the framework of the nonlinear Schroedinger equation. Catastrophic self-focusing and spatio-temporal splitting of the pulses is investigated. For the limiting case when the dispersive term of the pulse propagating in the normal dispersion regime can be neglected an indication of a possibility of a stable self-trapped propagation of both pulses is obtained.Comment: 18 pages (including 15 eps figures