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Abstract Teleoperation can enable human intervention to help handle instances of failure in autonomy thus allowing for much safer deployment of autonomous vehicle technology. Successful teleoperation requires recreating the environment around the remote vehicle using camera data received over wireless communication channels. This paper develops a new predictive display system to tackle the significant time delays encountered in receiving camera data over wireless networks. First, a new high gain observer is developed for estimating the position and orientation of the ego vehicle. The novel observer is shown to perform accurate state estimation using only GNSS and gyroscope sensor readings. A vector field method which fuses the delayed camera and Lidar data is then presented. This method uses sparse 3D points obtained from Lidar and transforms them using the state estimates from the high gain observer to generate a sparse vector field for the camera image. Polynomial based interpolation is then performed to obtain the vector field for the complete image which is then remapped to synthesize images for accurate predictive display. The method is evaluated on real-world experimental data from the nuScenes and KITTI datasets. The performance of the high gain observer is also evaluated and compared with that of the EKF. The synthesized images using the vector field based predictive display are compared with ground truth images using various image metrics and offer vastly improved performance compared to delayed images. 

Teleoperation is increasingly used in the operation of delivery robots and is beginning to be utilized for certain autonomous vehicle intervention applications. This paper addresses the challenges in teleoperation of an autonomous vehicle due to latencies in wireless communication between the remote vehicle and the teleoperator station. Camera video images and Lidar data are typically delayed during wireless transmission but are critical for proper display of the remote vehicle's real-time road environment to the teleoperator. Data collected with experiments in this project show that a 0.5 second delay in real-time display makes it extremely difficult for the teleoperator to control the remote vehicle. This problem is addressed in the paper by using a predictive display (PD) system which provides intermediate updates of the remote vehicle's environment while waiting for actual camera images. The predictive display utilizes estimated positions of the ego vehicle and of other vehicles on the road computed using model-based extended Kalman filters. A crucial result presented in the paper is that vehicle motion models need to be inertial rather than relative and so tracking of other vehicles requires accurate localization of the ego vehicle itself. An experimental study using 5 human teleoperators is conducted to compare teleoperation performance with and without predictive display. A 0.5 second time-delay in camera images makes it impossible to control the vehicle to stay in its lane on curved roads, but the use of the developed predictive display system enables safe remote vehicle control with almost as accurate a performance as the delay-free case. 

Abstract Myxobacteria are non-photosynthetic bacteria distinguished among prokaryotes by a multicellular stage in their life cycle known as fruiting bodies that are formed in response to nutrient deprivation and stimulated by light. Here, we report an entrained, rhythmic pattern ofMyxococcus macrosporusfruiting bodies, forming consistently spaced concentric rings when grown in the dark. Light exposure disrupts this rhythmic phenotype, resulting in a sporadic arrangement and reduced fruiting-body count.M. macrosporusgenome encodes a red-light photoreceptor, a bacteriophytochrome (BphP), previously shown to affect the fruiting-body formation in the related myxobacteriumStigmatella aurantiaca. Similarly, the formation ofM. macrosporusfruiting bodies is also impacted by the exposure to BphP—specific wavelengths of light. RNA-Seq analysis ofM. macrosporusrevealed constitutive expression of thebphPgene. Phytochromes, as light-regulated enzymes, control many aspects of plant development including photomorphogenesis. They are intrinsically correlated to circadian clock proteins, impacting the overall light-mediated entrainment of the circadian clock. However, this functional relationship remains unexplored in non-photosynthetic prokaryotes. Genomic analysis unveiled the presence of multiple homologs of cyanobacterial core oscillatory gene,kaiC, in various myxobacteria, includingM. macrosporus,S. aurantiaca and M. xanthus. RNA-Seq analysis verified the expression of allkaiChomologs inM. macrosporusand the closely relatedM. xanthus, which lacksbphPgenes. Overall, this study unravels the rhythmic growth pattern duringM. macrosporusdevelopment, governed by environmental factors such as light and nutrients. In addition, myxobacteria may have a time-measuring mechanism resembling the cyanobacterial circadian clock that links the photoreceptor (BphP) function to the observed rhythmic behavior. Graphical abstract 

ABSTRACT Many bacterial histidine kinases work in two-component systems that combine into larger multi-kinase networks. NahK is one of the kinases in the GacS Multi-Kinase Network (MKN), which is the MKN that controls biofilm regulation in the opportunistic pathogenPseudomonas aeruginosa. This network has also been associated with regulating many virulence factorsP. aeruginosasecretes to cause disease. However, the individual role of each kinase is unknown. In this study, we identify NahK as a novel regulator of the phenazine pyocyanin (PYO). Deletion ofnahKleads to a fourfold increase in PYO production, almost exclusively through upregulation of phenazine operon two (phz2). We determined that this upregulation is due to mis-regulation of allP. aeruginosaquorum-sensing (QS) systems, with a large upregulation of thePseudomonasquinolone signal system and a decrease in production of the acyl-homoserine lactone-producing system,las. In addition, we see differences in expression of quorum-sensing inhibitor proteins that align with these changes. Together, these data contribute to understanding how the GacS MKN modulates QS and virulence and suggest a mechanism for cell density-independent regulation of quorum sensing. IMPORTANCEPseudomonas aeruginosais a Gram-negative bacterium that establishes biofilms as part of its pathogenicity.P. aeruginosainfections are associated with nosocomial infections. As the prevalence of multi-drug-resistantP. aeruginosaincreases, it is essential to understand underlying virulence molecular mechanisms. Histidine kinase NahK is one of several kinases inP. aeruginosaimplicated in biofilm formation and dispersal. Previous work has shown that the nitric oxide sensor, NosP, triggers biofilm dispersal by inhibiting NahK. The data presented here demonstrate that NahK plays additional important roles in theP. aeruginosalifestyle, including regulating bacterial communication mechanisms such as quorum sensing. These effects have larger implications in infection as they affect toxin production and virulence. 

We vary the inflow properties in a finite-volume solver to investigate their effects on the computed cyclonic motion in a right-cylindrical vortex chamber. The latter comprises eight tangential injectors through which steady-state air is introduced under incompressible and inviscid conditions. To minimize cell skewness around injectors, a fine tetrahedral mesh is implemented first and then converted into polyhedral elements, namely, to improve convergence characteristics and precision. Once convergence is achieved, our principal variables are evaluated and compared using a range of inflow parameters. These include the tangential injector speed, count, diameter, and elevation. The resulting computations show that well-resolved numerical simulations can properly predict the forced vortex behavior that dominates in the core region as well as the free vortex tail that prevails radially outwardly, beyond the point of peak tangential speed. It is also shown that augmenting the mass influx by increasing the number of injectors, injector size, or average injection speed, further amplifies the vortex strength and all peak velocities while shifting the mantle radially inwardly. Overall, the axial velocity is found to be the most sensitive to vertical displacements of the injection plane. By raising the injection plane to the top half portion of the chamber, the flow character is markedly altered, and an axially unidirectional vortex is engendered, particularly, with no upward motion or mantle formation. Conversely, the tangential and radial velocities are found to be axially independent and together with the pressure distribution prove to be the least sensitive to injection plane relocations. 

We vary the inflow properties in a finite-volume solver to investigate their effects on the computed cyclonic motion in a right-cylindrical vortex chamber. The latter comprises eight tangential injectors through which steady-state air is introduced under incompressible and inviscid conditions. To minimize cell skewness around injectors, a fine tetrahedral mesh is implemented first and then converted into polyhedral elements, namely, to improve convergence characteristics and precision. Once convergence is achieved, our principal variables are evaluated and compared using a range of inflow parameters. These include the tangential injector speed, count, diameter, and elevation. The resulting computations show that well-resolved numerical simulations can properly predict the forced vortex behavior that dominates in the core region as well as the free vortex tail that prevails radially outwardly, beyond the point of peak tangential speed. It is also shown that augmenting the mass influx by increasing the number of injectors, injector size, or average injection speed further amplifies the vortex strength and all peak velocities while shifting the mantle radially inwardly. Overall, the axial velocity is found to be the most sensitive to vertical displacements of the injection plane. By raising the injection plane to the top half portion of the chamber, the flow character is markedly altered, and an axially unidirectional vortex is engendered, particularly, with no upward motion or mantle formation. Conversely, the tangential and radial velocities are found to be axially independent and together with the pressure distribution prove to be the least sensitive to injection plane relocations.