Structural disorder versus chiral magnetism in Cr1/3_{1/3}NbS2_2

The crystal structure of a disordered form of Cr$_{1/3}$NbS$_2$ has been characterized using diffraction and inelastic scattering of synchrotron radiation. In contrast to the previously reported symmetry (P6$_3$22), the crystal can be described by a regular twinning of an average P6$_3$ structure with three disordered positions of the Cr ions. Short-range correlations of the occupational disorder result in a quite intense and structured diffuse scattering; a static nature of the disorder was unambiguously attributed by the inelastic x-ray scattering. The diffuse scattering has been modeled using a reverse Monte-Carlo algorithm assuming a disorder of the Cr sub-lattice only. The observed correlated disorder of the Cr sub-lattice reduces the temperature of the magnetic ordering from 130 K to 88 K and drastically modifies the field dependence of the magnetization as it is evidenced by the SQUID magnetometery. We conclude, that in contrast to the helicoidal spin structure assumed for P6$_3$22 form, the compound under study is ferromagnetically ordered with a pronounced in-plane anisotropy

Chiral criticality in doped Mn1−y_{1-y}Fey_ySi compounds

The critical spin fluctuations in doped compounds Mn$_{1-y}$Fe$_y$Si have been studied by means of ac-susceptibility measurements, polarized neutron small angle scattering and spin echo spectroscopy. It is shown that these compounds undergo the transition from the paramagnetic to helimagnetic phase through continuous, yet well distinguishable crossovers: (i) from paramagnetic to partially chiral, (ii) from partially chiral to highly chiral fluctuating state. The crossover points are identified on the basis of combined analysis of the temperature dependence of ac-susceptibility and polarized SANS data. The whole transition is marked by two inflection point of the temperature dependence of ac-susceptibility: the upper one corresponds to the crossover to partially chiral state at $T^*$, where the inverse correlation length $\kappa \approx 2 k$, the lower one corresponds to the transition to the spin helix structure. The intermediate crossover to the highly chiral phase is observed at the inflection point $T_k$ of the first derivative of ac-susceptibility, where $\kappa \approx k$. The temperature crossovers to the highly chiral fluctuating state is associated with the enhancing influence of the Dzyaloshinskii-Moria interaction close to $T_c$.Comment: 5 pages, 5 figures, 1 table, 13 cite

Toolkit for Simulation Modeling of Logistics Warehouse in Distributed Computing Environment

We address an important problem of an automation of logistics warehouses simulation modeling in distributed service-oriented computing environments. To this end, we propose new approach for adjusting management system parameters of real warehouse in production use. It is based on the integration of the conceptual, wireframe and service-oriented programming used to develop parameter sweep applications and data analysis in the simulation modeling process. We develop a toolkit for supporting modeling of warehouse logistics. The practical experiments are focused upon the refrigerated warehouse. The developed application demonstrates high efficiency and scalability for optimizing nine criteria to cope with different production demands.The study was supported by the Russian Foundation of Basic Research, projects no. 15-29-07955 and no. 16-07-00931, and Program 1.33P of fundamental research of Presidium RAS, project “Development of new approaches to creation and study of complex models of information-computational and dynamic systems with applications”

Магнитно-резонансная диагностика жидкостных скоплений при остром интерстициальном панкреатите

The article analyses MR examinations of 160 patients with interstitial acute pancreatitis, in absence of MR signs of necrosis of pancreatic parenchyma; the incidence of fluid collections and their outcomes are estimated. Small single fluid collections in the first day after an attack of acute pancreatitis were revealed in 27.5% of cases, multiple and large fluid collections without signs of parenchymal necrosis were revealed in 15.6%. Follow-up MR examinations showed full resolution of peripancreatic fluid collections in 78.7% of cases. Resistant unencapsulated and partially encapsulated collections were found in 7 of 47 patients (14.9%). Local complications requiring surgical intervention developed exclusively in patients with fluid collections and amounted to 1.9% of the whole group of 160 patients, and 6.4% of patients with acute pancreatitis without signs of necrosis of pancreas and peripancreatic fat, but with fluid collections.The authors came to the conclusion that routine MR examinations of patients with interstitial acute pancreatitis were indicated for patients with fluid collections to estimate the dynamics of changes (resolution of collections or development of complications).В статье проанализированы магнитно-резонансные (МР) исследования 160 пациентов с легкой формой острого панкреатита при отсутствии МР-признаков некроза паренхимы поджелудочной железы, оценена частота жидкостных скоплений и их исходы. Одиночные, небольших размеров жидкостные скопления в первые сутки после атаки острого панкреатита выявлены в 27,5% случаев, множественные и большие скопления жидкости выявлены в 15,6%. Контрольные МР-исследования показали полное рассасывание ретроперитонеальных скоплений жидкости в 78,7% случаев. Стойкие неинкапсулированные и частично инкапсулированные скопления определены у 7 (14,9%) пациентов из 47. Локальные осложнения, потребовавшие хирургического вмешательства, развились исключительно у пациентов с жидкостными скоплениями, и составили 1,9% на всю группу, а у больных с жидкостными скоплениями — 6,4%.Авторы исследования пришли к выводу, что стандартные МР-исследования у пациентов с легкими интерстициальными формами острого панкреатита показаны больным со скоплениями жидкости для определения динамики развития изменений (рассасывание или развитие осложнений)