Autonomous exploration is an important application of multi-vehicle systems, where a team of networked robots are coordinated to explore an unknown environment collaboratively. This technique has earned significant research interest due to its usefulness in search and rescue, fault detection and monitoring, localization and mapping, etc. In this paper, a novel cooperative exploration strategy is proposed for multiple mobile robots, which reduces the overall task completion time and energy costs compared to conventional methods. To efficiently navigate the networked robots during the collaborative tasks, a hierarchical control architecture is designed which contains a high-level decision making layer and a low-level target tracking layer. The proposed cooperative exploration approach is developed using dynamic Voronoi partitions, which minimizes duplicated exploration areas by assigning different target locations to individual robots. To deal with sudden obstacles in the unknown environment, an integrated deep reinforcement learning based collision avoidance algorithm is then proposed, which enables the control policy to learn from human demonstration data and thus improve the learning speed and performance. Finally, simulation and experimental results are provided to demonstrate the effectiveness of the proposed scheme.

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Sorafenib in combination with cytarabine resulted in strong anti-AML activity in vitro and in vivo. These results warrant clinical evaluation of sorafenib with cytarabine-based regimens in molecularly heterogeneous AML.

Ten new phenolic compounds including the six neolignans 1 -3 and 6 -8 and four caffeoyl derivatives, i.e., myo-inositol 1-caffeate (9), myo-inositol 6-caffeate (10), myo-inositol 5-caffeate (11), and paucine 3'-b-d-glucopyranoside (12) were isolated from the whole plants of Selaginella moellendorffii (caffeic acid ¼ 3-(3,4-dihydroxyphenyl)prop-2-enoic acid). Their structures were established by spectroscopic and chemical methods.Introduction. -Selaginella moellendorffii Hieron. (Selaginellaceae), a perennial herb, is mainly distributed in the southern area of the Changjiang River in China and has been used to treat jaundice, gonorrhea, bleeding, acute hepatitis, and idiopathic thrombocytopenic purpura (ITP) [5] biflavones in this plant. In our recent research, a series of pyrrolidinoindoline alkaloids were found from this plant [6]. In continuation of the studies on this plant, ten new phenolic derivatives, 1 -3 and 6 -12, and four known ones, compounds 4 and 5, paucine (¼ (2E)-N-(4-aminobutyl)-3-(3,4-dihydroxyphenyl)prop-2-enamide 13) [7], and N