Paraneoplastic neurological syndrome: focus on the involvement of the peripheral nervous system

The information about epidemiology, pathogenesis and clinical heterogeneity of paraneoplastic neurological syndrome is summarized and based on Russian and foreign literature. The main attention is devoted to the affection of peripheral nervous systems in patients with oncological diseases. We report the information about anti-neuronal antibodies associated with paraneoplastic syndrome. The diagnostic criteria of paraneoplastic neurological syndromes are presented.</p

Wave kinetics of random fibre lasers

Traditional wave kinetics describes the slow evolution of systems with many degrees of freedom to equilibrium via numerous weak non-linear interactions and fails for very important class of dissipative (active) optical systems with cyclic gain and losses, such as lasers with non-linear intracavity dynamics. Here we introduce a conceptually new class of cyclic wave systems, characterized by non-uniform double-scale dynamics with strong periodic changes of the energy spectrum and slow evolution from cycle to cycle to a statistically steady state. Taking a practically important example—random fibre laser—we show that a model describing such a system is close to integrable non-linear Schrödinger equation and needs a new formalism of wave kinetics, developed here. We derive a non-linear kinetic theory of the laser spectrum, generalizing the seminal linear model of Schawlow and Townes. Experimental results agree with our theory. The work has implications for describing kinetics of cyclical systems beyond photonics

Large negative velocity gradients in Burgers turbulence

We consider 1D Burgers equation driven by large-scale white-in-time random force. The tails of the velocity gradients probability distribution function (PDF) are analyzed by saddle-point approximation in the path integral describing the velocity statistics. The structure of the saddle-point (instanton), that is velocity field configuration realizing the maximum of probability, is studied numerically in details. The numerical results allow us to find analytical solution for the long-time part of the instanton. Its careful analysis confirms the result of [Phys. Rev. Lett. 78 (8) 1452 (1997) [chao-dyn/9609005]] based on short-time estimations that the left tail of PDF has the form ln P(u_x) \propto -|u_x|^(3/2).Comment: 10 pages, RevTeX, 10 figure

Long-time dynamics of the infinite-temperature Heisenberg magnet

Infinite-temperature long-time dynamics of Heisenberg model ${\bf\hat{H}}=-\frac{1}{2}\sum_{i,j}J_{ij} \hat{\vec{S}}_{i}\hat{\vec{S}}_{j}$ is investigated. It is shown that the quantum spin pair-correlator is equal to the correlator of classically evaluated vector field averaged over the initial conditions with respect to the gaussian measure. In the continious limit case the scaling estimations allow one to find one-point correlator that turns out to be $C(\vec{r}=0;t)\propto const \times t^{-6/7}$. All results are obtained by straightforward procedure without any assumptions of the phenomenological character.Comment: 11 pages, RevTex 3.0, to be published in PRB Feb. 199

Hereditary neuropathies: systematization and diagnostics (clinical case of hereditary motor and sensor neuropathy of the IA type)

Aim: to study the value of routine methods (clinical symptoms, electrophysiological findings and results of DNA analysis) in diagnostics of hereditary motor sensory neuropathy type IA in outpatient clinics. Material and Methods. The review of foreign literature is represented. The phenotypic polymorphism, genetic heterogeneity and the difficulties of diagnostics are identified. A family with hereditary motor sensory neuropathy of lAtype is presented, which was diagnosed on the base of available methods in outpatient practice (clinical symptoms, genealogical method, electro-physiological findings and DNA analysis results). Results. Routine algorithm (consistent valuation of clinical symptoms, neurophysiologic findings and the results of DNA analysis) helped to verify the diagnosis of hereditary motor sensory neuropathy of lAtype in outpatient practice after more than 20 years of the onset of the disease. Conclusion. The neurologists of outpatient clinics and other specialists must be informed about the availability of diagnostics of hereditary diseases of nervous system

1d-disordered conductor with loops immersed in a magnetic field

We investigate the conductance of a 1-D disordered conducting loop with two contacts, immersed in a magnetic flux. We show the appearance in this model of the Al’tshuler-Aronov-Spivak behaviour. We also investigate the case of a chain of loops distributed with finite density: in this case we show that the interference effects due to the presence of the loops can lead to the delocalization of the wave function.

Polyneuropathy: clinical polymorphism and the algorithms of diagnostics

The information about epidemiology and clinical polymorphism of neuropathies is summarized on the base of Russian and foreign literature. The algorithm of clinical observation in patients with polyneuropathy is presented

Aristarchus Lewkowski — the founder of Saratov's Neurology (the 150th anniversary of his birth)

The article presents the information about the life, career and scientific work of Aristarchus Lewkowski — the founder of Saratov'sNeurological science school and the creator of outpatient neurological services