A reaction-diffusion model predicts the intracellular length scale over which EGFR-initiated GAB1-SHP2 complexes persist

Activation of receptor tyrosine kinases (RTKs) leads to the assembly of multi-membered protein complexes connected by phosphotyrosine-SH2 domain linkages. However, these linkages are relatively weak and reversible, which allows complex disassembly to occur on a time scale that permits phosphatases to dephosphorylate complex members and thereby regulate complex persistence. Here, we generated a computational reaction-diffusion model to predict the length scale over which membrane-bound RTKs can regulate the maintenance of such protein complexes through the intermediary action of diffusible cytoplasmic kinases. Specifically, we show that the RTK EGFR can activate SRC family kinases (SFKs) to maintain the association of SHP2 with phosphorylated GAB1, which activates SHP2, throughout the entire cell volume. This finding is dependent on the ability of SFKs to be activated by EGFR at the plasma membrane and subsequently diffuse through the cytosol, as altering the model topology to permit only SFK activation at the plasma membrane reduces the length scale of GAB1-SHP2 association. Modifying the model topology to neglect GAB1 binding to cytosolic and EGFR-bound GRB2 had little effect on this length scale. Indeed, a model sensitivity analysis identified protein diffusion, SFK inactivation, and GAB1 dephosphorylation as the processes that most strongly control the distance over which GAB1-SHP2 persists distal from EGFR. A model scaling analysis likewise predicted that the length scale of GAB1-SHP2 association is greatly extended compared to that of SFK activation and that GAB1-SHP2 complexes persist throughout the cell volume. Furthermore, the same processes identified in the model sensitivity analysis appeared in the length scale estimate for GAB1-SHP2 association. In vitro experiments using proximity ligation assay and immunofluorescence against GAB1-SHP2 and EGFR, respectively, suggested that GAB1-SHP2 complexes are distributed throughout cells and exist distally from EGFR during EGF stimulation. Overall, our results suggest that GAB1-SHP2 complexes—and thus active SHP2—can persist distally from EGFR due to re-phosphorylation of GAB1 throughout the cytosol by EGFR-activated SFKs.

Improved Thevenin Equivalent Model of MMC Considering Pre-charge Conditions and DC Side Fault Conditions

The traditional Thevenin equivalent Modular Multilevel Converter (MMC) model has poor versatility for the two working conditions of pre-charging and DC-side faults. In this paper, an improved Thevenin equivalent MMC model considering pre-charge conditions and DC side fault conditions is proposed. The model divides the pre-charging condition into a Controllable charging stage and an Uncontrollable charging stage. The DC-side fault condition is divided into the pre-blocking and post-blocking conditions of the converter. The circuit characteristics are analyzed, and the equivalent model topology is comprehensively improved to make it suitable for full-condition simulation, and a control strategy suitable for the equivalent model is proposed. The detailed model and the proposed improved equivalent model were built in PSCAD/EMTDC for comparison and analysis. The simulation results shows that the improved equivalent model can be applied to various working conditions, and the versatility of the traditional Thevenin equivalent model is improved.

Interaction between atmospheric model resolution and energy system model topology

<p>With the increasing penetration of renewable energy capacities in the European energy system, the electricity generators have shifted from centralized power plants to decentralized, weather-dependent wind turbines and photovoltaic systems. Energy system models now rely on skillful weather data to estimate renewable energy feedins on electricity bus levels. These feedins are usually calculated by bilinearly interpolating the closest atmospheric model grid points to the electricity network bus locations. This comes to the cost of averaging multiple atmospheric model grid points reducing overall atmospheric model variability. In addition, electricity grids are often modeled in clustered representations in terms of number of lines and buses. The number of buses is usually much smaller than the number of atmospheric model grid points and therefore some grid points and their characteristics may not be taken into account in highly clustered networks. So far, this interconnection between atmospheric model resolution and electricity grid topology has not been widely investigated.</p><p>This study approaches the question if and to what extent the atmospheric model resolution affects the energy system model results. The regional reanalysis COSMO-REA6 is used as a reference data and its resolution is artificially reduced. This allows to compare the loss of information (mainly variability) due to a lower grid point resolution. The weather data is then used within different energy system network topologies to determine the corresponding renewable energy feedins at bus levels. A subsequent optimal power flow model estimates the impact on energy system metrics as storage usage and economic dispatch costs to further understand the relationship between atmospheric model resolution and energy system model topology. This study provides useful insights to choose the appropriate resolution of the atmospheric model input given an energy system model. </p>

Acoustic model topology optimization for large vocabulary speech recognition

Acoustic model topology selection work in constructing large vocabulary speech recognition systems is being done empirically or heuristically. In this paper, we propose two improved algorithms, which are based on Genetic Algorithm (GA) and Particle Swarm Optimization (PSO) respectively, on the basis of our previously proposed algorithms to select and optimize model topologies for small or medium vocabulary speech recognition systems. Our improved algorithms attain the goal of optimizing acoustic model topologies for large vocabulary speech recognition systems mainly through modifying the encoding schemes of our previously proposed algorithms. Experiments on the dialogue corpus of Inner Mongolia University show that, compared with the conventional acoustic model topology selection method, our newly proposed algorithms are able to bring much higher recognition performance for large vocabulary speech recognition systems by optimizing their acoustic model topologies.

Control of a stand-alone photovoltaic/battery bank system to supply energy to resistance load

<p><span lang="EN-US">In this paper, supervisor control for stand-alone hybrid power system to supply energy to resistance load is presented. The hybrid system is used to produce energy withoutinterruption and it consists of a photovoltaic generator (PV), and a battery bank. PV system work in parallel via DC/DC converter and the battery bank is used to store the excess of energy. The mathematical model topology, the identification of each subsystem and the control supervision of theglobal system are the contribution of this paper. Obtained results under Matlab/Simulink presented and discussed.</span></p>

Research on the GUI Testing Based on the Bayesian Network Model

Graphical User Interfaces (GUI) is becoming increasingly important in the software field, while GUI testing is becoming the key issues restricting GUI rapid development. GUI testing mainly serves two goals: to establish confidence in assessment of GUI and find more software defects in GUI testing. For this purpose, any testing method must be better at detecting defects. However, GUI testing is faced with many challenges due to the immense number of event interactions. In this paper, it introduces a Bayesian model guiding the process of GUI testing, discusses the Bayesian model topology and its issues encountered in the modeling process. In the end, a case reveals the validity of the GUI testing model.