Game-Based Approximate Optimal Motion Planning for Safe Human-Swarm Interaction.

Safety as a fundamental requirement for human-swarm interaction has attracted a lot of attention in recent years. Most existing approaches solve a constrained optimization problem at each time step, which has a high real-time requirement. To deal with this challenge, this article formulates the safe human-swarm interaction problem as a Stackerberg-Nash game, in which the optimization is performed over the entire time domain. The leader robot is supposed to be in a dominant position, interacting directly with the human operator to realize trajectory tracking and responsible for guiding the swarm to avoid obstacles. The follower robots always take their best responses to leader's behavior with the purpose of achieving the desired formation. Following the bottom-up principle, we first design the best-response controllers, that is, Nash equilibrium strategies, for the followers. Then, a Lyapunov-like control barrier function-based safety controller and a learning-based formation tracking controller for the leader are designed to realize safe and robust cooperation. We show that the designed controllers can make the robotic swarms move in a desired geometric formation following the human command and modify their motion trajectories autonomously when the human command is unsafe. The effectiveness of the proposed approach is verified through simulation and experiments. The experiment results further show that safety can still be guaranteed even when there exists a dynamic obstacle.

Adaptive ELM-Based Security Control for a Class of Nonlinear-Interconnected Systems With DoS Attacks.

This article is concerned with the output feedback security control of a class of high-order nonlinear-interconnected systems with denial-of-service (DoS) attacks, nonlinear dynamics, and exogenous disturbances. First, extreme learning machine (ELM) and adaptive techniques are adopted to approximate the unknown nonlinearities. Then, novel adaptive ELM-based nonlinear state observers with adaptive compensation functions are developed to estimate the unmeasurable states during DoS attacks under the influence of the disturbances. Further, by combining with the backstepping control and filtering techniques, adaptive ELM-based controllers are proposed to achieve uniformly ultimately bounded results based on the observation and adaption control signals under the influence of DoS attacks, nonlinear dynamics, and exogenous disturbances. Comparative studies are carried out to validate the effectiveness of the developed ELM-based adaptive observation and control strategies for two interconnected power systems.

The Impact of Team Knowledge Heterogeneity on Entrepreneurial Opportunity Identification: A Moderated Mediation Model.

PURPOSE: Due to the low success rate of entrepreneurship, the correct identification of entrepreneurial opportunities is one of the important concerns in the field of entrepreneurship research. Therefore, this study focuses on the influence mechanism of entrepreneurial opportunity identification, so as to enrich the influence path of entrepreneurial opportunity identification and provide suggestions for improving the success rate of entrepreneurship. METHODS: After screening and judging the quality of the questionnaires, the valid questionnaires were numbered and matched with 106 team samples. The researchers carried out telephone communication with participants to ask for their attendance, and then took samples on-site at the appointed time and place. RESULTS: The results show that: (1) team knowledge heterogeneity has a significant positive impact on entrepreneurial opportunity identification. (2) Social capital plays a mediating role between team knowledge heterogeneity and entrepreneurial opportunity identification. (3) Promotional regulatory focus, a type of regulation that tends to adopt a radical approach to achieve goals, positively moderates the mediating effect of team knowledge heterogeneity on entrepreneurial opportunity identification through social capital. However, preventive regulatory focus, a type of regulation that tends to adopt a cautious and vigilant way to achieve goals, has no moderating effect. DISCUSSION: In order to improve the correct identification of entrepreneurial opportunities, it is necessary to establish team with knowledge heterogeneity rationally and excavate different levels of social capital behind heterogeneous members. In addition, it also reveals that team style can retain certain promotive in the process of entrepreneurship, which is conducive to the feasibility and profitability of entrepreneurial opportunity identification.

Down-regulation of Polη expression leads to increased DNA damage, apoptosis and enhanced S phase arrest in L-02 cells exposed to hydroquinone.

DNA polymerase eta (Polη), the product of the xeroderma pigmentosum variant gene, is required for translesion DNA synthesis, and plays a pivotal role in preventing genome instability after DNA damage induced by genotoxic agents. Studies have previously suggested a link between Polη and susceptibility to hydroquinone (HQ)-induced toxicity. To further address the role of Polη in the response of L-02 cells to HQ, we employed RNA interference to silence Polη expression in L-02 cells and examined the susceptibility of these Polη-deficient cells to the toxic effects of HQ. In this study, cell survival rate was determined using the MTT assay, DNA damage was determined by the Comet assay, apoptosis and cell cycle distribution were determined using flow cytometry, the mRNA expression levels of Polη were determined by real-time PCR, and the protein expression levels of Polη and γ-H2AX were determined by Western blot, γ-H2AX foci were visualized by confocal laser scanning fluorescence microscopy after cells were exposed to HQ at various concentrations for 24h in vitro. The results showed that stable Polη-knockdown cells were successfully constructed and more than 80% inhibition of Polη expression was confirmed. The results also showed that down-regulation of Polη led to a decrease in cell proliferation and an enhanced susceptibility to HQ-induced cytotoxicity. Polη-deficient cells were 2-fold more sensitive to HQ when compared with nonspecific siRNA control cells. Moreover, Polη-silenced L-02 cells treated with HQ displayed an increased level of DNA double-strand breaks as measured by olive tail moment, and an elevated DNA damage response as indicated by the induction of γ-H2AX. In addition, knockdown of Polη resulted in more enhanced apoptosis and more pronounced S phase arrest following HQ treatment. Together, these results show that Polη plays an important role in the response of L-02 cells to HQ-induced DNA damage.

SiO(2) nanoparticles induce global genomic hypomethylation in HaCaT cells.

The increasing amount of nanotechnological products, found in our environment and those applicable in engineering, material sciences and medicine has stimulated a growing interest in examining their long-term impact on genetic and epigenetic processes. We examined here the epigenomic response to nm-SiO(2) particles in human HaCaT cells and methyltransferases (DNMTs) and DNA-binding domain proteins (MBDs) induced by nano-SiO(2) particles. Nm-SiO(2) treatment induced global hypoacetylation implying a global epigenomic response. The levels of DNMT1, DNMT3a and methyl-CpG binding protein 2 (MBD2) were also decreased in a dose dependent manner at mRNA and protein level. Epigenetic changes may have long-term effects on gene expression programming long after the initial signal has been removed, and if these changes remain undetected, it could lead to long-term untoward effects in biological systems. These studies suggest that nanoparticles could cause more subtle epigenetic changes which merit thorough examination of environmental nanoparticles and novel candidate nanomaterials for medical applications.