477 research outputs found

    Full Counting Statistics of Superconductor--Normal-Metal Heterostructures

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    The article develops a powerful theoretical tool to obtain the full counting statistics. By a slight extension of the standard Keldysh method we can access immediately all correlation functions of the current operator. Embedded in a quantum generalization of the circuit theory of electronic transport, we are able to study the full counting statistics of a large class of two-terminal contacts and multi-terminal structures, containing superconductors and normal metals as elements. The practical use of the method is demonstrated in many examples.Comment: 35 pages, contribution to "Quantum Noise", ed. by Yu.V. Nazarov and Ya.M. Blanter, minor changes in text, references adde

    The kink-type instability of toroidal stellar magnetic fields with thermal diffusion

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    The stability of toroidal magnetic fields in rotating radiative stellar zones is studied for realistic values of both the Prandtl numbers. The two considered models for the magnetic geometry represent fields with odd and even symmetry with respect to the equator. In the linear theory in Boussinesq approximation the resulting complex eigenfrequency (including growth rate and drift rate) are calculated for a given radial wavenumber of a nonaxisymmetric perturbation with m=1. The ratio of the Alfven frequency, \Omega_A, to the rate of the basic rotation, \Omega, controls the eigenfrequency of the solution. For strong fields with \Omega_A > \Omega the solutions do not feel the thermal diffusion. The growth rate runs with \Omega_A and the drift rate is close to -\Omega so that the magnetic pattern will rest in the laboratory system. For weaker fields with \Omega_A < \Omega the growth rate strongly depends on the thermal conductivity. For fields with dipolar parity and for typical values of the heat conductivity the resulting very small growth rates are almost identical with those for vanishing gravity. For fields with dipolar symmetry the differential rotation of any stellar radiative zone (like the solar tachocline) is shown as basically stabilizing the instability independent of the sign of the shear. Finally, the current-driven kink-type instability of a toroidal background field is proposed as a model for the magnetism of Ap stars. The recent observation of a lower magnetic field treshold of about 300 Gauss for Ap stars is understood as corresponding to the minimum magnetic field producing the instability.Comment: 11 pages, 7 figures, acc. for publicatio

    Spike train statistics for consonant and dissonant musical accords in a simple auditory sensory model

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    The phenomena of dissonance and consonance in a simple auditory sensory model composed of three neurons are considered. Two of them, here so-called sensory neurons, are driven by noise and subthreshold periodic signals with different ratio of frequencies, and its outputs plus noise are applied synaptically to a third neuron, so-called interneuron. We present a theoretical analysis with a probabilistic approach to investigate the interspike intervals statistics of the spike train generated by the interneuron. We find that tones with frequency ratios that are considered consonant by musicians produce at the third neuron inter-firing intervals statistics densities that are very distinctive from densities obtained using tones with ratios that are known to be dissonant. In other words, at the output of the interneuron, inharmonious signals give rise to blurry spike trains, while the harmonious signals produce more regular, less noisy, spike trains. Theoretical results are compared with numerical simulations

    Regularity of Spike Trains and Harmony Perception in a Model of the Auditory System

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    Spike train regularity of the noisy neural auditory system model under the influence of two sinusoidal signals with different frequencies is investigated. For the increasing ratio m/n of the input signal frequencies (m, n are natural numbers) the linear growth of the regularity is found at the fixed difference (m - n). It is shown that the spike train regularity in the model is high for harmonious chords of input tones and low for dissonant ones

    Role of Superficial CD200 Marker in Differential Diagnosis of Malignant B-Cell Lymphoproliferative Diseases

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    Background & Aims. Flow cytometry is successfully used for diagnosis of malignant lymphoproliferative disorders. However, there are atypical cases that are difficult to interpret; thus, new markers relevant for the differential diagnosis are to be searched for. The aim is to analyze CD200 expression in patients with B-cell lymphoproliferative disorders. Materials & Methods. 187 patients with chronic lymphocytic leukemia (CLL), 14 patients with mantle cell lymphoma (MCL), 9 patients with marginal zone lymphoma (MZL), and 5 patients with hairy cell leukemia (HCL) were enrolled in the study. Neoplasm was not confirmed in 12 subjects. The patients underwent the following tests: CBC, immunophenotyping of peripheral blood or bone marrow lymphocytes, and a cytogenetic test. In some cases, an additional immunohistochemical test of bone marrow trepanobiopsy or lymph node biopsy samples was required. Results. In all cases of CLL and HCL, the CD200 expression was positive; mean fluorescence intensity was higher in these cases as compared to other groups. Negative expression of CD200 prevailed in MCL patients; however, at the same time 2 cases of intermediate and positive expression were reported, both showing moderate fluorescence intensity values. CD200 expression was heterogeneous in MZL patients. Conclusion. The CD200 negative expression excludes typical HCL and CLL. Additional cytogenetic and immunnohistoсhemical tests should be performed in such cases to verify the diagnosis, first of all, MCL or MZL

    Effect of IGHV Gene Mutation Status and BCR Structure Stereotypy on Effectiveness of BR Regimen in First-Line Therapy of Chronic Lymphocytic Leukemia

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    Background & Aims. The IGHV gene mutation status is a constant biological feature of tumor cells in chronic lymphocytic leukemia (CLL). This parameter is an important predictor of the efficacy of immunochemotherapy. It was included into the CLL international prognostic index CLL-IPI developed recently. The aim is to evaluate the prognostic significance of the BR regimen in patients with different variants of the B-cell receptor (BCR) structure. Methods. The study examined immediate and delayed treatment outcomes for 183 CLL patients included in a Russian, prospective, observational BEN-001 trial (NCT02110394). The median age was 61 years (range: 35–79); 53/179 (29.6 %) patients were older than 65; and 14/179 (7.8 %) patients were older than 75. Prevalence of males (110/179, 61.5 %) in the male/female ratio (1.6:1.0) was observed. Most patients had advanced disease: Binet B 116/173 (67 %) or Binet C 38/173 (22 %). The patients received the first-line therapy according to the BR regimen at standard doses in 36 hematological institutions in the Russian Federation over the period from 2012 until 2015. The genome DNA isolated from mononuclear leukocytes in the peripheral blood was used to assess the mutation status of the IGHV-genes. Results. The study demonstrated that unmutated CLL (≄ 98 % of homology to germline gene) is associated with worsening of the event-free and overall survival rates most of all; at that, the complete remission rate and the MRD-free survival rate were the same. Conclusion. It is reasonable to analyze the IGHV mutation status in all patients prescribed with the BR regimen as the first-line therapy

    FEATURES OF THE APPLICATION OF THE NEW METAL FIXATOR FOR OSTEOSYNTHESIS IN OSTEOPENIA IN POST-MORTEM EXAMINATION

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    Aim - to study the peculiarities of osteosynthesis in osteopenia with the application of the new metal fixator in post-mortem studies. Material and methods. New metal fixator for osteosynthesis in osteopenia has been developed. Measurements of the mechanical strength of osteosynthesis, and biomechanical tests of osteosynthesis stability with the application of this fixator were studied in 16 corpses (32 cases). Results. Biomechanical tests indicate that the new metal fixator is able to maintain the optimal position of anatomical reduction in 15 cases out of 16, while using a sponge screw AO type shows this result only in 6 cases out of 10. The mechanical strength of osteosynthesis with the use of the new metal fixator is 2,77 times greater than when using a sponge screw AO type. Conclusion. The carried out post-mortem examination testifies to the advantage of using the new metal fixator compared to the traditionally used sponge screw AO type for osteosynthesis in osteopenia

    Nuclear forward scattering in particulate matter: dependence of lineshape on particle size distribution

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    In synchrotron Moessbauer spectroscopy, the nuclear exciton polariton manifests itself in the lineshape of the spectra of nuclear forward scattering (NFS) Fourier-transformed from time domain to frequency domain. This lineshape is generally described by the convolution of two intensity factors. One of them is Lorentzian related to free decay. We derived the expressions for the second factor related to Frenkel exciton polariton effects at propagation of synchrotron radiation in Moessbauer media. Parameters of this Frenkelian shape depend on the spatial configuration of Moessbauer media. In a layer of uniform thickness, this factor is found to be a simple hypergeometric function. Next, we consider the particles spread over a 2D surface or diluted in non-Moessbauer media to exclude an overlap of ray shadows by different particles. Deconvolving the purely polaritonic component of linewidths is suggested as a simple procedure sharpening the experimental NFS spectra in frequency domain. The lineshapes in these sharpened spectra are theoretically expressed via the parameters of the particle size distributions (PSD). Then, these parameters are determined through least-squares fitting of the line shapes.Comment: 13 pages, 12 figure
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