The selection of the mutation strategy for differential evolution (DE) algorithm plays an important role in the optimization performance, such as exploration ability, convergence accuracy and ...convergence speed. To improve these performances, an improved differential evolution algorithm with neighborhood mutation operators and opposition-based learning, namely NBOLDE, is developed in this paper. In the proposed NBOLDE, the new evaluation parameters and weight factors are introduced into the neighborhood model to propose a new neighborhood strategy. On this basis, a new neighborhood mutation strategy based on DE/current-to-best/1, namely DE/neighbor-to-neighbor/1, is designed in order to replace large-scale global mutation by local neighborhood mutation with high search efficiency. Then, a generalized opposition-based learning is employed to optimize the initial population and select the better solution between the current solution and reverse solution in order to approximate global optimal solution, which can amend the convergence direction, accelerate convergence, improve efficiency, enhance the stability and avoid premature convergence. Finally, the proposed NBOLDE is compared with four state-of-the-art DE variants by 12 benchmark functions with low-dimension and high-dimension. The experiment results indicate that the proposed NBOLDE has a faster convergence speed, higher convergence accuracy, and better optimization capabilities in solving high-dimensional complex functions.
All multicellular organisms keep a balance between sink and source activities by controlling nutrient transport at strategic positions. In most plants, photosynthetically produced sucrose is the ...predominant carbon and energy source, whose transport from leaves to carbon sink organs depends on sucrose transporters. In the model plant Arabidopsis thaliana, transport of sucrose into the phloem vascular tissue by SUCROSE TRANSPORTER 2 (SUC2) sets the rate of carbon export from source leaves, just like the SUC2 homologs of most crop plants. Despite their importance, little is known about the proteins that regulate these sucrose transporters. Here, identification and characterization of SUC2-interaction partners revealed that SUC2 activity is regulated via its protein turnover rate and phosphorylation state. UBIQUITIN-CONJUGATING ENZYME 34 (UBC34) was found to trigger turnover of SUC2 in a light-dependentmanner. The E2 enzyme UBC34 could ubiquitinate SUC2 in vitro, a function generally associated with E3 ubiquitin ligases. ubc34 mutants showed increased phloem loading, as well as increased biomass and yield. In contrast, mutants of another SUC2-interaction partner, WALLASSOCIATED KINASE LIKE 8 (WAKL8), showed decreased phloem loading and growth. An in vivo assay based on a fluorescent sucrose analog confirmed that SUC2 phosphorylation byWAKL8 can increase transport activity. Both proteins are required for the up-regulation of phloemloading in response to increased light intensity. The molecular mechanism of SUC2 regulation elucidated here provides promising targets for the biotechnological enhancement of source strength.
Pseudomonas aeruginosa is a highly pathogenic bacterium known for its ability to sense and coordinate the production of virulence factors in response to host immune responses. However, the regulatory ...mechanisms underlying this process have remained largely elusive. In this study, we investigate the two-component system CprRS in P. aeruginosa and unveil the crucial role of the sensor protein CprS in sensing the human host defense peptide LL-37, thereby modulating bacterial virulence. We demonstrate that CprS acts as a phosphatase in the presence of LL-37, leading to the phosphorylation and activation of the response regulator CprR. The results prove that CprR directly recognizes a specific sequence within the promoter region of the HigBA toxin-antitoxin system, resulting in enhanced expression of the toxin HigB. Importantly, LL-37-induced HigB expression promotes the production of type III secretion system effectors, leading to reduced expression of proinflammatory cytokines and increased cytotoxicity towards macrophages. Moreover, mutations in cprS or cprR significantly impair bacterial survival in both macrophage and insect infection models. This study uncovers the regulatory mechanism of the CprRS system, enabling P. aeruginosa to detect and respond to human innate immune responses while maintaining a balanced virulence gene expression profile. Additionally, this study provides new evidence and insights into the complex regulatory system of T3SS in P. aeruginosa within the host environment, contributing to a better understanding of host-microbe communication and the development of novel strategies to combat bacterial infections.
In recent years, the artificial ground freezing (AGF) method has been widely used in subway construction, and the engineering properties of soil have changed significantly after freezing and thawing. ...In this paper, a series of dynamic triaxial tests were used to investigate the pore pressure development of freeze-thaw soft clay under different cyclic dynamic stress ratios, loading frequencies and freezing temperatures. The test results show that the types of normalization pore pressure development include developmental and stable. An empirical model, considering the effects of cyclic dynamic stress ratio, loading frequency, freezing temperature and number of cyclic loading, was proposed and compared with three representative models proposed by the predecessors to validate that the proposed method has the best estimation on the development of the pore pressure.
•The type of pore pressure development in frozen-thawed clay contains two parts.•An empirical model for predicting pore pressure development is proposed.•Freeze-thaw cycle plays an important role on the pore pressure development.•The model can be used for stable and developmental type of pore pressure development.
is a grave nosocomial pathogen that persistently inhabits the lungs of patients with cystic fibrosis (CF) and causes various chronic infections. The bacterial toxin-antitoxin (TA) system is ...associated with latent and long-term infections, but the underlying mechanisms remain to be fully characterized.
We here investigated the diversity and function of five genomic type II TA systems widely distributed among
clinical isolates. We also examined the distinct structural features of the toxin protein from different TA systems and characterized their contributions to persistence, invasion ability, and intracellular infection caused by
.
ParDE, PA1030/PA1029, and HigBA could modulate persister cell formation under treatment with specific antibiotics. Furthermore, cell-based transcriptional and invasion assays revealed that PA1030/PA1029 and HigBA TA systems were critical for intracellular survival.
Our results highlight the prevalence and diverse roles of type II TA systems in
and evaluate the possibility of using PA1030/PA1029 and HigBA TA pairs as targets for novel antibiotic treatments.
The artificial ground freezing (AGF) technique has been extensively employed in the construction of underground structures. Due to the existence of freeze-thaw cycle in the AGF technique, the ...properties of soft clay deteriorate and thus larger settlement is induced during its later operation phase. To investigate the strain behaviors of the soft clay undergoing freeze-thaw cycle and discuss the differences between the soft clay undergoing and without undergoing freeze-thaw cycle under dynamic cyclic loading, a series of dynamic triaxial tests with consideration of different influencing factors as dynamic stress amplitudes, freezing temperatures, and freezing temperatures were conducted. Based on the experimental data, an empirical model for predicting the accumulative plastic strain was proposed and validated. Besides, the microscopic structural characters of the artificially freeze-thaw soft clay were explored via mercury intrusion porosimetry (MIP) tests. The results show that the total accumulative plastic strain of specimens increases with the increase of the dynamic stress amplitude, while decrease with the increase of the loading frequency. The specimens undergoing freeze-thaw cycle produces larger plastic strain, and the lower the freezing temperature is, the larger the total accumulative plastic strain is. The empirical accumulative plastic strain model, which can synthetically reflect the effects of dynamic stress amplitudes, loading frequencies, freezing temperatures and number of cyclic loading is proposed and validated. The freeze-thaw cycle has a significant effect on the strain behavior of soft clay in a way decreasing the pore volume and increasing the pore size of the specimens. Results obtained in this paper may provide meaningful references for studying the deformation characteristics of the soft clay in engineering applications.
•The effects of dynamic stress amplitude and loading frequency on the accumulative plastic strain of soft clay were discussed.•The effects of freeze-thaw cycle as well as various freezing temperature on the accumulative plastic strain behaviour of soft clay was investigated.•An empirical model for predicting the long-term strain of soft clay, can synthetically reflect the effects of dynamic stress amplitudes, loading frequencies, freezing temperatures and number of cyclic loading was proposed and validated.•The microscopic structural mechanism of dynamic stress amplitude, loading frequency and freezing temperature on affecting the accumulative plastic strain of soft clay was analyzed.
In the past few decades, a lot of optimization methods have been applied in estimating the parameter of photovoltaic (PV) models and obtained better results, but these methods still have some ...deficiencies, such as higher time complexity and poor stability. To tackle these problems, an enhanced success history adaptive DE with greedy mutation strategy (EBLSHADE) is employed to optimize parameters of PV models to propose a parameter optimization method in this paper. In the EBLSHADE, the linear population size reduction strategy is used to gradually reduce population to improve the search capabilities and balance the exploitation and exploration capabilities. The less and more greedy mutation strategy is used to enhance the exploitation capability and the exploration capability. Finally, a parameter optimization method based on EBLSHADE is proposed to optimize parameters of PV models. The different PV models are selected to prove the effectiveness of the proposed method. Comparison results demonstrate that the EBLSHADE is an effective and efficient method and the parameter optimization method is beneficial to design, control, and optimize the PV systems.
In this paper, a theoretical estimation model of TBM thrust, torque, and power in the rock–soil interface (RSI) of mixed ground is developed, including a new force model for the drag cutter that ...accounts for chamber pressure and soil friction. A distribution model of the disc cutters and drag cutters on the cutterhead adaptable to different excavation surfaces is built in order to visualize the cutting process as the TBM cutterhead rotates, and a program is created and that runs smoothly using the Python version 3.8, which can recognize the numbers and calculate the forces of the disc cutters and drag cutters in the soft and hard strata, respectively. Then, combining with friction forces and chamber pressure calculated by the program, the variation in torque, thrust, and power are produced. Subsequently, a new index (MPPI), which considers both the thrust of the TBM and cutterhead torque, for forecasting TBM tunneling performance in composite strata is presented. The reliability of the index as well as the estimation model are validated using data from an actual project to offer recommendations for future tunneling projects.
Adult human mesenchymal stem cells (MSCs) hold promise for an increasing list of therapeutic uses due to their ease of isolation, expansion, and multi‐lineage differentiation potential. To maximize ...the clinical potential of MSCs, the underlying mechanisms by which MSC functionality is controlled must be understood. We have taken a deconstructive approach to understand the individual components in vitro, namely the role of candidate “stemness” genes. Our recent microarray gene expression profiling data suggest that interleukin‐6 (IL‐6) may contribute to the maintenance of MSCs in their undifferentiated state. In this study, we showed that IL‐6 gene expression is significantly higher in undifferentiated MSCs as compared to their chondrogenic, osteogenic, and adipogenic derivatives. Moreover, we found that MSCs secrete copious amounts of IL‐6 protein, which decreases dramatically during osteogenic differentiation. We further evaluated the role of IL‐6 for maintenance of MSC “stemness,” using a series of functional assays. The data showed that IL‐6 is both necessary and sufficient for enhanced MSC proliferation, protects MSCs from apoptosis, inhibits adipogenic and chondrogenic differentiation of MSCs, and increases the rate of in vitro wound healing of MSCs. We further identified ERK1/2 activation as the key pathway through which IL‐6 regulates both MSC proliferation and inhibition of differentiation. Taken together, these findings show for the first time that IL‐6 maintains the proliferative and undifferentiated state of bone marrow‐derived MSCs, an important parameter for the optimization of both in vitro and in vivo manipulation of MSCs. J. Cell. Biochem. 108: 577–588, 2009. Published 2009 Wiley‐Liss, Inc.
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