Harvesting random embedding for high-frequency change-point detection in temporal complex systems.

Recent investigations have revealed that dynamics of complex networks and systems are crucially dependent on the temporal structures. Accurate detection of the time instant at which a system changes its internal structures has become a tremendously significant mission, beneficial to fully understanding the underlying mechanisms of evolving systems, and adequately modeling and predicting the dynamics of the systems as well. In real-world applications, due to a lack of prior knowledge on the explicit equations of evolving systems, an open challenge is how to develop a practical and model-free method to achieve the mission based merely on the time-series data recorded from real-world systems. Here, we develop such a model-free approach, named temporal change-point detection (TCD), and integrate both dynamical and statistical methods to address this important challenge in a novel way. The proposed TCD approach, basing on exploitation of spatial information of the observed time series of high dimensions, is able not only to detect the separate change points of the concerned systems without knowing, a priori, any information of the equations of the systems, but also to harvest all the change points emergent in a relatively high-frequency manner, which cannot be directly achieved by using the existing methods and techniques. Practical effectiveness is comprehensively demonstrated using the data from the representative complex dynamics and real-world systems from biology to geology and even to social science.

Study on degradation characteristics of imazamox by Streptomycetaceae.

The residues of imazamox (IMX) will cause phytotoxicity to subsequent crops after long-term use, and will also pollute the soil and its surrounding environment. This study isolates and identifies two strains of Streptomycetaceae JX02 and JX06 that can effectively degrade IMX. Use response surface method Box-Behnken design to optimize physicochemical parameters. The optimal degradation conditions of strains JX02 and JX06 are obtained and verified: IMX concentration is 150 mg L-1, the initial dosage is 9.9%, 9.1% (OD600 = 0.1), the temperature is 26.4 and 27.5 °C, and pH value is 7.0 and 7.7, respectively. The degradation rates of 150 mg L-1 IMX detected by HPLC within 4 d were 99 and 94%, respectively. After adding strains JX02 and JX06, the half-life of IMX in the soil is shortened to 11 d and 13 d, indicating that Streptomycetaceae had a positive effect on the remediation of soil. It is expected to provide scientific information for the rational use, environmental safety evaluation of IMX, and provide a basis for future research and development of microbial agents.

Plant-microbial remediation of chlorpyrifos contaminated soil.

With the development of modern agriculture, the pollution caused by the use of chemical fertilizers and pesticides has become a serious problem, posing a threat to human health and the living environment. The remediation of plant microorganisms has been seen as an economical, effective, and eco-friendly method of cleaning up soils contaminated with organophosphorus pesticides. In this study, white-rot fungi were immobilized by adsorption method, a plant-microbial remediation met was established. The data results show that after 30 days, the combined remediation system for corn microbes increased the rate of chlorpyrifos degradation by 18% compared to the single remediation of the plant, and the rate of combined remediation of ryegrass microbes increased by 23%. The effect of CPF content in soil on the combined remediation is mainly reflected in the significant difference in the number of microorganisms (P < 0.05). In this article, plant-microbial remediation were applied to soil contaminated by CPF, which provides a new idea for the remediation of pesticide-contaminated soil. Combined bioremediation may be a better alternative to mitigate the impact of high pollution on microorganisms at different pollutant concentrations compared to single microbial remediation or phytoremediation.