Modeling of continuous melting of quartz-feldspar raw materials of subsequent flow from the plasma heating

The problem of obtaining easy-flowing melt silicate-containing materials with the use of low-temperature plasma. A mathematical formulation of the evolution of the silicate-containing raw material to the melt. The analysis of the preliminary results

Verification of model of calculation of intra-chamber parameters in hybrid solid-propellant rocket engines

On the basis of obtained analytical estimate of characteristics of hybrid solid-propellant rocket engine verification of earlier developed physical and mathematical model of processes in a hybrid solid-propellant rocket engine for quasi-steady-state flow regime was performed. Comparative analysis of calculated and analytical data indicated satisfactory comparability of simulation results

Energy and propulsion optimization of solid-propellant grain of a hybrid power device

A method of distribution of an additional solid-phase component (oxidizer) providing uniformity of grain burning for the purpose of evaluation and optimization of energy and propulsion parameters of hybrid solid-propellant motor is proposed in the paper

Comparative analysis of two-dimensional and three-dimensional modeling of heat transfer during operation of a gas infrared heater indoor

Relevance. It is proposed to heat local work areas with systems based on gas infrared heaters, capable of directing radiative heat flow to reduce heating costs in large premises. However, the widespread use of gas infrared heaters is hampered by the existing difficulties with the preliminary assessment of convective-radiative heat flows movement, on which the number and location of heating devices depends. The preliminary assessment is complicated by the need in some cases for 3D modeling of complex physical processes. It is necessary to evaluate the possibility of replacing labor-intensive 3D modeling with a method for calculating a heating system using gas infrared emitters based on a 2D approach to reduce the time spent on calculations. Aim. To prove that the use of a two-dimensional model of the processes under consideration makes it possible to obtain the main characteristics of the thermal regime of the premises, making it possible to replace spatial modeling. Objects. Heating system with a light-type gas infrared heater and an air exchange system. Methods. Two-dimensional and three-dimensional mathematical modeling of conjugate heat transfer processes using the finite element method. Mathematical modeling was carried out in the COMSOL Multiphysics software environment using the modules: “Heat Transfer Interface in Liquids”, “Radiation between Surfaces” and “Turbulent Flow, k-ε Interface”. Results. The article presents the results of mathematical modeling performed in three-dimensional and two-dimensional formulations. The distribution of temperatures in the air and enclosing structures, as well as the flow lines of heated air and air, which was heating, in the volume of the premise are presented. The results of two-dimensional and three-dimensional modeling were compared. Satisfactory similarity of the calculated average air temperatures in the local working area was established based on the results. The difference was less than 2℃ for different spatial modeling approaches

НАБЛЮДЕНИЯ СЛАБЫХ ЗЕМЛЕТРЯСЕНИЙ ГИДРОФОННОЙ СТАНЦИЕЙ НА МЕЛКОВОДЬЕ ЮЖНЫХ КУРИЛЬСКИХ ОСТРОВОВ

Results of hydroacoustic observations of signals from weak earthquakes in natural conditions in the region of the Southern Kuril Islands are presented. Some earthquakes were registered by the the Yuzhno-Kurilsk Seismic Station, other were only recorded by hydrophone stations. The observations were specific as seismic signals were recorded in shallow waters, i.e. in high noise level conditions. Hydrophones were installed in Lake Lagunnoe (Kunashir) and Khromovaya Bay (Shikotan). Our analysis of hydroacoustic records received from the hydrophone stations revealed no evident precursory response of the geological medium to weak distant events. This means that neither before the period of earthquake preparation nor during the earthquake preparation period, any geoacoustic emission was not detected. It is shown that despite the unfavourable noise level conditions, even distant weak earthquakes can be confidently registered by hydrophone stations, and pending application of proper signal processing techniques, it can be possible to determine arrival times of seismic waves and to measure parameters of seismic waves. It is also established that the frequency spectrum of acoustic signals from the weak earthquakes recordable by the hydrophone stations is continuous and of noise type in the frequency range up to 90–100 Hz. It is revealed that in some cases, weak earthquakes and microearthquakes may be forerun by low frequency signals.Представлены результаты натурных гидроакустических наблюдений слабых землетрясений в районе Южных Курильских островов. Часть землетрясений была зарегистрирована и Южно-Курильской сейсмостанцией, а часть – только гидрофонной станцией. Особенностью наблюдений являлось то, что запись сейсмических сигналов проводилась на мелководье, т.е. в условиях повышенного уровня помех. Места постановки гидрофонов: озеро Лагунное (о. Кунашир) и бухта Хромовая (о. Шикотан). Анализ гидроакустических записей с гидрофонной станции показал, что заметной предваряющей реакции региональной геосреды на слабые отдаленные события не произошло, т.е. геоакустической эмиссии не наблюдалось ни до подготовки, ни в период подготовки событий. В работе показано, что, несмотря на неблагоприятную помеховую обстановку, даже отдаленные слабые землетрясения уверенно регистрируются гидрофонными станциями, а применение соответствующей обработки сигналов дает возможность выделять моменты вступления сейсмических волн и измерения их параметров. Установлено также, что частотный спектр акустических сигналов от слабых удаленных землетрясений, воспринимаемых гидрофонными станциями, носит непрерывный шумоподобный характер в диапазоне частот до 90–100 Гц. Обнаружено, что некоторым слабым землетрясениям и микроземлетрясениям может предшествовать низкочастотный упреждающий сигнал (НУС)

Formality theorems for Hochschild complexes and their applications

We give a popular introduction to formality theorems for Hochschild complexes and their applications. We review some of the recent results and prove that the truncated Hochschild cochain complex of a polynomial algebra is non-formal.Comment: Submitted to proceedings of Poisson 200

Novel robust biomarkers for human bladder cancer based on activation of intracellular signaling pathways

Sherpa Romeo blue journal. Open access article. Creative Commons Attribution 3.0 License (CC BY 3.0) applies.We recently proposed a new bioinformatic algorithm called OncoFinder for quantifying the activation of intracellular signaling pathways. It was proved advantageous for minimizing errors of high-throughput gene expression analyses and showed strong potential for identifying new biomarkers. Here, for the first time, we applied OncoFinder for normal and cancerous tissues of the human bladder to identify biomarkers of bladder cancer. Using Illumina HT12v4 microarrays, we profiled gene expression in 17 cancer and seven non-cancerous bladder tissue samples. These experiments were done in two independent laboratories located in Russia and Canada. We calculated pathway activation strength values for the investigated transcriptomes and identified signaling pathways that were regulated differently in bladder cancer (BC) tissues compared with normal controls. We found, for both experimental datasets, 44 signaling pathways that serve as excellent new biomarkers of BC, supported by high area under the curve (AUC) values. We conclude that the OncoFinder approach is highly efficient in finding new biomarkers for cancer. These markers are mathematical functions involving multiple gene products, which distinguishes them from “traditional” expression biomarkers that only assess concentrations of single genes.Ye

Switches, Excitable Responses and Oscillations in the Ring1B/Bmi1 Ubiquitination System

In an active, self-ubiquitinated state, the Ring1B ligase monoubiquitinates histone H2A playing a critical role in Polycomb-mediated gene silencing. Following ubiquitination by external ligases, Ring1B is targeted for proteosomal degradation. Using biochemical data and computational modeling, we show that the Ring1B ligase can exhibit abrupt switches, overshoot transitions and self-perpetuating oscillations between its distinct ubiquitination and activity states. These different Ring1B states display canonical or multiply branched, atypical polyubiquitin chains and involve association with the Polycomb-group protein Bmi1. Bistable switches and oscillations may lead to all-or-none histone H2A monoubiquitination rates and result in discrete periods of gene (in)activity. Switches, overshoots and oscillations in Ring1B catalytic activity and proteosomal degradation are controlled by the abundances of Bmi1 and Ring1B, and the activities and abundances of external ligases and deubiquitinases, such as E6-AP and USP7

Cell-signalling dynamics in time and space

The specificity of cellular responses to receptor stimulation is encoded by the spatial and temporal dynamics of downstream signalling networks. Computational models provide insights into the intricate relationships between stimuli and responses and reveal mechanisms that enable networks to amplify signals, reduce noise and generate discontinuous bistable dynamics or oscillations. These temporal dynamics are coupled to precipitous spatial gradients of signalling activities, which guide pivotal intracellular processes, but also necessitate mechanisms to facilitate signal propagation across a cell