Development of a formalism of movable cellular automaton method for numerical modeling of fracture of heterogeneous elastic-plastic materials

A general approach to realization of models of elasticity, plasticity and fracture of heterogeneousmaterials within the framework of particle-based numerical methods is proposed in the paper. It is based onbuilding many-body forces of particle interaction, which provide response of particle ensemble correctlyconforming to the response (including elastic-plastic behavior and fracture) of simulated solids. Implementationof proposed approach within particle-based methods is demonstrated by the example of the movable cellularautomaton (MCA) method, which integrates the possibilities of particle-based discrete element method (DEM)and cellular automaton methods. Emergent advantages of the developed approach to formulation of manybodyinteraction are discussed. Main of them are its applicability to various realizations of the concept ofdiscrete elements and a possibility to realize various rheological models (including elastic-plastic or visco-elasticplastic)and models of fracture to study deformation and fracture of solid-phase materials and media.Capabilities of particle-based modeling of heterogeneous solids are demonstrated by the problem of simulationof deformation and fracture of particle-reinforced metal-ceramic composites

Nonlinear focusing of Terahertz laser beam using layered superconductor

We theoretically study the propagation of a Terahertz (THz) Gaussian beam through a thin sample of layered superconductor. We consider the beam axis and the superconducting layers to be perpendicular to the sample interface, while the electric field in the beam is perpendicular to the layers. We show that, in such a geometry, the Josephson current between the superconducting layers supports lensing of the beam instead of divergence on the Rayleigh range. Moreover, due to the nonlinearity, the focal length and waist of the transmitted beam depend on the incident beam intensity. These dependences demonstrate nontrivial hysteresis behavior that can be observed in experiments with THz lasers

Synthesis of nitroxyl radical by direct nucleophilic functionalization of a C-H bond in the azadiene systems

Cyclic dinitrones underwent nucleophilic substitution of the hydrogen atom in the reaction with a paramagnetic carbanion, the lithium derivative of 4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-oxyl 3-oxide, to give polyfunctional nitronyl nitroxyls. © 2012 Springer Science+Business Media New York

Kudoa unicapsula n. sp. (Myxosporea: Kudoidae) a parasite of the Mediterranean mullets Liza ramada and L. aurata (Teleostei: Mugilidae)

A new multivalvulid myxozoan parasite, Kudoa unicapsula n. sp., is described from the intestinal mesentery, intestine and pyloric caeca of the thin-lipped grey mullet Liza ramada (Risso 1826) and the golden grey mullet L. aurata (Risso, 1810) from the Mediterranean coastal waters of Spain. It is characterized by the presence of elongated, rice corn-like white cysts of 0.47–0.56×0.18–0.38 mm, filled with tetracapsulate, slightly asymmetric spores, rectangular in apical view and tear-shaped in lateral view with four polar capsules of considerably different size and slightly unequal spore valves with rounded edges, overlapping each other on the apex of the spore. One large polar capsule includes a polar filament coiled in two to three turns, and the other three polar capsules, which are very small, posses only a rudimental filament. Both light and electron microscopy data showed that this species differs from all previously described Kudoa spp. with unequal polar capsules. The molecular analysis based on 18S and 28S ribosomal deoxyribonucleic acid DNA sequence data of K. unicapsula n. sp. indicates a close relationship and thus phylogenetic clustering together with K. trifolia, a myxozoan from the same host and the same geographical location

Design and development of undercarriage systems for agricultural tractors with replaceable half-tracks

The need to use such propulsion devices in mobile agricultural power units is substantiated. The relevance of this development based on global trends is shown. The purpose of the research is to develop the design, to evaluate strain-stress state and functional characteristics of undercarriages of agricultural tractors with replaceable half-tracks. An experimental design of the replaceable tracked undercarriage was developed and manufactured, modeling of loading modes was performed, calculations were carried out by the finite element method of the stress-strain state of structural elements according to 6 load schemes – tractor parking on a flat horizontal surface; movement with maximum traction force; parking across a 30° slope for the upper track; parking across a 30° slope for the lower caterpillar; driving into an obstacle with a deviation of 15°; driving over obstacles based on the central rollers. It was determined that the selected structural material, by the above mentioned loading modes ensure the operability of replaceable tracked undercarriage. Calculations were carried out to check the adequacy of the developed mathematical model using field tests in testing ground of FSAC VIM. It was determined that the maximum stress-strain state of the frame structure of a replaceable tracked undercarriage for all types of loading did not exceed 100 MPa. This provides a two-fold margin of safety in terms of fluidity of the structure, taking into account the characteristics of the selected material. In the maximum loaded state - parking across a slope of 30° - the highest stress on the upper track is 161 MPa, which corresponds to a safety margin of 1.45. The deformation of the bearing assembly was no more than 4 mm, which is allowed by the design of the drive assembly and the caterpillar

Withdrawal of inhaled corticosteroids in COPD patients: rationale and algorithms

COPD; Treatment algorithm; Guideline adherenceEPOC; Algoritmo de tratamiento; Adherencia a la guía clínicaMPOC; Algoritme de tractament; Adherència a la guia clínicaObservational studies indicate that overutilization of inhaled corticosteroids (ICS) is common in patients with chronic obstructive pulmonary disease (COPD). Overprescription and the high risk of serious ICS-related adverse events make withdrawal of this treatment necessary in patients for whom the treatment-related risks outweigh the expected benefits. Elaboration of an optimal, universal, user-friendly algorithm for withdrawal of ICS therapy has been identified as an important clinical need. This article reviews the available evidence on the efficacy, risks, and indications of ICS in COPD, as well as the benefits of ICS treatment withdrawal in patients for whom its use is not recommended by current guidelines. After discussing proposed approaches to ICS withdrawal published by professional associations and individual authors, we present a new algorithm developed by consensus of an international group of experts in the field of COPD. This relatively simple algorithm is based on consideration and integrated assessment of the most relevant factors (markers) influencing decision-making, such a history of exacerbations, peripheral blood eosinophil count, presence of infection, and risk of community-acquired pneumonia