RDMNet: Reliable Dense Matching Based Point Cloud Registration for Autonomous Driving

Point cloud registration is an important task in robotics and autonomous driving to estimate the ego-motion of the vehicle. Recent advances following the coarse-to-fine manner show promising potential in point cloud registration. However, existing methods rely on good superpoint correspondences, which are hard to be obtained reliably and efficiently, thus resulting in less robust and accurate point cloud registration. In this paper, we propose a novel network, named RDMNet, to find dense point correspondences coarse-to-fine and improve final pose estimation based on such reliable correspondences. Our RDMNet uses a devised 3D-RoFormer mechanism to first extract distinctive superpoints and generates reliable superpoints matches between two point clouds. The proposed 3D-RoFormer fuses 3D position information into the transformer network, efficiently exploiting point clouds' contextual and geometric information to generate robust superpoint correspondences. RDMNet then propagates the sparse superpoints matches to dense point matches using the neighborhood information for accurate point cloud registration. We extensively evaluate our method on multiple datasets from different environments. The experimental results demonstrate that our method outperforms existing state-of-the-art approaches in all tested datasets with a strong generalization ability.Comment: 11 pages, 9 figure

Metabolic perturbation of Streptomyces albulus by introducing NADP-dependent glyceraldehyde 3-phosphate dehydrogenase

The available resources of Streptomyces represent a valuable repository of bioactive natural products that warrant exploration. Streptomyces albulus is primarily utilized in the industrial synthesis of ε-poly-L-lysine (ε-PL). In this study, the NADP-dependent glyceraldehyde 3-phosphate dehydrogenase (GapN) from Streptococcus mutans was heterologously expressed in S. albulus CICC11022, leading to elevated intracellular NADPH levels and reduced NADH and ATP concentrations. The resulting perturbation of S. albulus metabolism was comprehensively analyzed using transcriptomic and metabolomic methodologies. A decrease in production of ε-PL was observed. The expression of gapN significantly impacted on 23 gene clusters responsible for the biosynthesis of secondary metabolites. A comprehensive analysis revealed a total of 21 metabolites exhibiting elevated levels both intracellularly and extracellularly in the gapN expressing strain compared to those in the control strain. These findings underscore the potential of S. albulus to generate diverse bioactive natural products, thus offering valuable insights for the utilization of known Streptomyces resources through genetic manipulation

Dynamic Capture Using a Traplike Soft Gripper With Stiffness Anisotropy

Dynamic capture is a common skill that humans have practiced extensively but is a challenging task for robots in which sensing, planning, and actuation must be tightly coordinated to deal with targets of diverse shapes, sizes, and velocity. In particular, the impact force may cause serious damage to a rigid gripper and even its carrier, e.g., a robotic arm. Existing soft grippers suffer from low speed and force to actively respond to capturing dynamic targets. In this article, we propose a soft gripper capable of efficient capture of dynamic targets, taking inspiration from the biological structures of multitentacled animals or plants. The presented gripper uses a cluster of tentacles to achieve an omnidirectional envelope and high tolerance to dynamic target during the capturing process. In addition, a stiffness anisotropy property is implemented to the tentacle structure to form a “trap” making it easy for the targets to enter yet difficult to escape. We also present an analytical model for the tentacle structure to describe its deformation during the collision with a target. In experiments, we construct a robotic prototype and demonstrate its ability to capture dynamic targets

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Phenotype evaluation on downy mildew resistance of spinach germplasm resources

Downy mildew is the main disease in the production of spinach.The selection and evaluation of germplasm resources is the implantation and basis of the breeding of spinach against downy mildew.In this study,the spinachtraits from different germplasm resources,such as botanical characteristics,reproduction cycle and disease resistance,which have downy mildew resistance,were identifiedby field observation.The results showed that the diversity index of 10 qualitative traits of 59 spinach germplasm resources was distributed between 0.25 and 1.23,and the coefficient of variation of 8 quantitative traits was between 24.25% and 42.80%,with an average of 29.54%.The identification of the resistance to downy mildew show that the spinach materials S1 to S36 are high-resistant materials,S37-S41 are disease-resistant materials,and S42-S59 are medium-resistant materials.The results of the bolting period survey showed that 81.4% of the materials belonged to early or middle bolting materials,18.6% of the spinach materials belonged to the late bolting materials.In conclusion,the spinach material S1 has an erect plant type,oval leaves,late bolting and high resistance to downy mildew,and there was no downy mildew disease in the test period,and the downy mildew disease index and incidence rate were both 0. It was excellent germplasm resource for resisting to spinach downy mildew and for late bolting breeding

Kinematics and statics of eccentric soft bending actuators with external payloads

Soft bending actuators, born with the considerable capacity of structural flexibility and environmental adaptability, have been widely favored for years. However, the highly nonlinear coupling between force and deformation in such robots are very complex, especially considering the external payloads. This paper puts forward a concept of eccentric soft bending actuators (ESBAs) that can exhibit different output characteristics by modifying the geometric parameters. A virtual trajectory based kinematic model is introduced to describe the deformation of ESBAs so that the screw theory based product of exponentials (POE) formula is applied to the analysis of such soft tentacle-like structures for the first time. Following this, the static model takes the input pressure, external payloads, and material parameters into account by utilizing the principle of minimum potential energy, making a generalized mathematical expression. The proposed model is then verified via finite element methods (FEM), and finally through experiments. An application example shows that the Particle Swarm Optimization (PSO) is introduced to find appropriate geometric parameters to make an ESBA have maximum stiffness. (C) 2019 Elsevier Ltd. All rights reserved

Oridonin ameliorates depressive-like behaviors induced by chronic unpredictable mild stress in mice via TXNIP/NLRP3 signaling pathway

Purpose: To investigate the effect and mechanism of oridonin in chronic unpredictable mild stress (CUMS)-induced depressive-like behaviors. Methods: CUMS was established using 6-week stress stimuli, including feed/water deprivation, night lighting, inverted light/dark cycle, and tail clamping. Depressive behaviors were analyzed using the sucrose preference test, forced swim test (FST), and tail suspension test (TST). Locomotor activity was analyzed using the open field test (OFT) while inflammatory cytokines were analyzed by enzyme-linked immunosorbent assay. The activation of the TXNIP/NLRP3 signaling pathway was evaluated by western blot. Results: Sucrose consumption of CUMS-treated mice was significantly decreased, while immobility times of the FST (control vs. CUMS, ~50 to 150 s; p < 0.01) and TST (Control vs. CUMS, ~50 to 130 s; p < 0.01) were increased; oridonin significantly reversed these effects. Spontaneous locomotor activities (crossing, rearing, and grooming) measured in the OFT were decreased after the CUMS procedure, and oridonin increased these activities (p < 0.01 vs. CUMS). Oridonin decreased the production of tumor necrosis factor alpha, interleukin (IL)-1β, IL-6, and monocyte chemoattractant protein-1 in the hippocampus of CUMS-treated mice and significantly inhibited activation of the TXNIP/NLRP3 pathway induced by CUMS. Conclusion: Oridonin ameliorates depressive-like behaviors in mice induced by CUMS, partly via TXNIP/NLRP3 signaling pathway. Thus, the findings provide evidence for the potential application of oridonin in depression therapy

Variable-gain control for continuum robots based on velocity sensitivity

Kinematic control for continuum robots usually involves an inverse model to provide actuator positions according to the desired end-tip position, as well as a servo controller at the actuator level. The resulting control performance of a continuum robot is then related to its kinematic characteristics that vary at different configurations. In this paper, a kinematic model for a typical rod-driven continuum robot is presented. Following this, a kinematic parameter, velocity sensitivity, is proposed to evaluate the kinematic characteristics of the continuum robot, indicating the contribution of the individual actuators to the instant movement of the end-tip when tracking a given path. Next, a variable gain control strategy is presented to tune the servo controller with respect to the varying velocity sensitivity along the path, reducing the fluctuation of the tracking errors in real time. The simulated and experimental results show that the presented methods can effectively smooth the movement of the continuum robot over its workspace by considering the coordination between the kinematic and servo controllers

Design and modeling of a soft robotic surface with hyperelastic material

While most existing soft robots have tentacle-like morphology, this paper extends the morphology of a soft robot from a curve to a surface. The presented robotic surface is fabricated using hyperelastic silicone material, and its morphology and deformation can be actively controlled through two pneumatic soft bending actuators embedded along the edges. Quasi-steady-state models of the embedded actuators and the surface structure are established using the principle of virtual work and elastic plate theory, respectively, and then combined to relate the input pressure and external force to the deformation of the soft surface. The complete model is validated experimentally against a robotic prototype where the error is within 5% of the side length of the surface for a number of actuation levels