Threshold Resonant Structure of the 232Th Neutron-Induced Fission Cross Section

The structures observed in the sub-threshold neutron-induced fission of ^{232}Th were investigated employing a recent developed model. Theoretical single-particle excitations of a phenomenological two-humped barrier are determined by solving a system of coupled differential equations for the motion along the optimal fission path. A rather good agreement with experimental data was obtained using a small number of independent parameters. It is predicted that the structure at 1.4 and 1.6 MeV is mainly dominated by spin 3/2 partial cross-section with small admixture of spin 1/2, while the structure at 1.7 MeV is given by a large partial cross section of spin 5/2.Comment: 17 pages 11 figure

Dispersion of Waves in Relativistic Plasmas with Isotropic Particle Distributions

The dispersion laws of Langmuir and transverse waves are calculated in the relativistic non-magnetized formalism for several isotropic particle distributions: thermal, power-law, relativistic Lorentzian $\kappa,$ and hybrid $\beta$. For Langmuir waves the parameters of superluminal undamped, subluminal damped principal and higher modes are determined for a range of distribution parameters. The undamped and principal damped modes are found to match smoothly. Principal damped and second damped modes are found not to match smoothly. The presence of maximum wavenumber is discovered above that no longitudinal modes formally exist. The higher damped modes are discovered to be qualitatively different for thermal and certain non-thermal distributions. Consistently with the known results, the Landau damping is calculated to be stronger for non-thermal power-law-like distributions. The dispersion law is obtained for the single undamped transverse mode. The analytic results for the simplest distributions are provided.Comment: 8 pages, 12 figures, accepted by Physics of Plasma

Bionic models for identification of biological systems

This article proposes a clinical decision support system that processes biomedical data. For this purpose a bionic model has been designed based on neural networks, genetic algorithms and immune systems. The developed system has been tested on data from pregnant women. The paper focuses on the approach to enable selection of control actions that can minimize the risk of adverse outcome. The control actions (hyperparameters of a new type) are further used as an additional input signal. Its values are defined by a hyperparameter optimization method. A software developed with Python is briefly described

Measurement of the 236^{236}U fission cross section and angular distributions of fragments from fission of 235^{235}U and 236^{236}U in the neutron energy range of 0.3-500 MeV

The $^{236}$U fission cross section and the angular distributions of fragments from fission of $^{235}$U and $^{236}$U were measured for incident neutron energies from 0.3 MeV to 500 MeV on the time-of-flight spectrometer of the neutron complex GNEIS at the NRC "Kurchatov Institute" -- PNPI. Fission fragments were registered using position-sensitive low-pressure multiwire counters. In the neutron energy range above 20 MeV, the angular distributions of $^{236}$U fission fragments were measured for the first time. The fission cross section of $^{236}$U$(n,f)$ was measured relative to the fission cross section of $^{235}$U$(n,f)$, which is an accepted international standard. The obtained data are compared with the results of other experimental works. Theoretical calculations of the fission cross section and the anisotropy of angular distribution of fission fragments for the $^{236}$U$(n,f)$ reaction performed within the framework of our approach are presented and discussed.Comment: 21 pages, 22 figures, revised version accepted for publication in Phys. Rev.

Critical Dynamics of Self-Organizing Eulerian Walkers

The model of self-organizing Eulerian walkers is numerically investigated on the square lattice. The critical exponents for the distribution of a number of steps ($\tau_l$) and visited sites ($\tau_s$) characterizing the process of transformation from one recurrent configuration to another are calculated using the finite-size scaling analysis. Two different kinds of dynamical rules are considered. The results of simulations show that both the versions of the model belong to the same class of universality with the critical exponents $\tau_l=\tau_s=1.75\pm 0.1$.Comment: 3 pages, 4 Postscript figures, RevTeX, additional information available at http://thsun1.jinr.dubna.su/~shche

Outlier detection and classification in sensor data streams for proactive decision support systems

A paper has a deal with the problem of quality assessment in sensor data streams accumulated by proactive decision support systems. The new problem is stated where outliers need to be detected and to be classified according to their nature of origin. There are two types of outliers defined; the first type is about misoperations of a system and the second type is caused by changes in the observed system behavior due to inner and external influences. The proposed method is based on the data-driven forecast approach to predict the values in the incoming data stream at the expected time. This method includes the forecasting model and the clustering model. The forecasting model predicts a value in the incoming data stream at the expected time to find the deviation between a real observed value and a predicted one. The clustering method is used for taxonomic classification of outliers. Constructive neural networks models (CoNNS) and evolving connectionists systems (ECS) are used for prediction of sensors data. There are two real world tasks are used as case studies. The maximal values of accuracy are 0.992 and 0.974, and F1 scores are 0.967 and 0.938, respectively, for the first and the second tasks. The conclusion contains findings how to apply the proposed method in proactive decision support systems

Study on the process of Fe (III) oxide fluorination

The article deals with a fundamentally new fluoride technology for obtaining fluoride materials, provides data on the kinetics of the process of fluorination of Fe oxide with fluorine, fluoride and ammonium bifluoride. The physical and chemical properties of obtained fluorides are shown: a study of the elemental composition, grain-size composition using the method of scanning electron microscopy and laser diffraction

Dissecting X-ray-emitting Gas around the Center of our Galaxy

Most supermassive black holes (SMBHs) are accreting at very low levels and are difficult to distinguish from the galaxy centers where they reside. Our own Galaxy's SMBH provides a uniquely instructive exception, and we present a close-up view of its quiescent X-ray emission based on 3 mega-second of Chandra observations. Although the X-ray emission is elongated and aligns well with a surrounding disk of massive stars, we can rule out a concentration of low-mass coronally active stars as the origin of the emission based on the lack of predicted Fe Kalpha emission. The extremely weak H-like Fe Kalpha line further suggests the presence of an outflow from the accretion flow onto the SMBH. These results provide important constraints for models of the prevalent radiatively inefficient accretion state.Comment: 18 pages, 5 PDF figures, pdflatex format; Final version, published in Scienc

On the observation of unusual high concentration of small chain-like aggregate ice crystals and large ice water contents near the top of a deep convective cloud during the CIRCLE-2 experiment

During the CIRCLE-2 experiment carried out over Western Europe in May 2007, combined in situ and remote sensing observations allowed to describe microphysical and optical properties near-top of an overshooting convective cloud (11 080 m/−58 °C). The airborne measurements were performed with the DLR Falcon aircraft specially equipped with a unique set of instruments for the extensive in situ cloud measurements of microphysical and optical properties (Polar Nephelometer, FSSP-300, Cloud Particle Imager and PMS 2-D-C) and nadir looking remote sensing observations (DLR WALES Lidar). Quasi-simultaneous space observations from MSG/SEVIRI, CALIPSO/CALIOP-WFC-IIR and CloudSat/CPR combined with airborne RASTA radar reflectivity from the French Falcon aircraft flying above the DLR Falcon depict very well convective cells which overshoot by up to 600 m the tropopause level. Unusual high values of the concentration of small ice particles, extinction, ice water content (up to 70 cm<sup>−3</sup>, 30 km<sup>−1</sup> and 0.5 g m<sup>−3</sup>, respectively) are experienced. The mean effective diameter and the maximum particle size are 43 μm and about 300 μm, respectively. This very dense cloud causes a strong attenuation of the WALES and CALIOP lidar returns. The SEVIRI retrieved parameters confirm the occurrence of small ice crystals at the top of the convective cell. Smooth and featureless phase functions with asymmetry factors of 0.776 indicate fairly uniform optical properties. Due to small ice crystals the power-law relationship between ice water content (IWC) and radar reflectivity appears to be very different from those usually found in cirrus and anvil clouds. For a given equivalent reflectivity factor, IWCs are significantly larger for the overshooting cell than for the cirrus. Assuming the same prevalent microphysical properties over the depth of the overshooting cell, RASTA reflectivity profiles scaled into ice water content show that retrieved IWC up to 1 g m<sup>−3</sup> may be observed near the cloud top. Extrapolating the relationship for stronger convective clouds with similar ice particles, IWC up to 5 g m<sup>−3</sup> could be experienced with reflectivity factors no larger than about 20 dBZ. This means that for similar situations, indication of rather weak radar echo does not necessarily warn the occurrence of high ice water content carried by small ice crystals. All along the cloud penetration the shape of the ice crystals is dominated by chain-like aggregates of frozen droplets. Our results confirm previous observations that the chains of ice crystals are found in a continental deep convective systems which are known generally to generate intense electric fields causing efficient ice particle aggregation processes. Vigorous updrafts could lift supercooled droplets which are frozen extremely rapidly by homogeneous nucleation near the −37 °C level, producing therefore high concentrations of very small ice particles at upper altitudes. They are sufficient to deplete the water vapour and suppress further nucleation as confirmed by humidity measurements. These observations address scientific issues related to the microphysical properties and structure of deep convective clouds and confirm that particles smaller than 50 μm may control the radiative properties in convective-related clouds. These unusual observations may also provide some possible insights regarding engineering issues related to the failure of jet engines commonly used on commercial aircraft during flights through areas of high ice water content. However, large uncertainties of the measured and derived parameters limit our observations