Fear-Neuro-Inspired Reinforcement Learning for Safe Autonomous Driving

Ensuring safety and achieving human-level driving performance remain challenges for autonomous vehicles, especially in safety-critical situations. As a key component of artificial intelligence, reinforcement learning is promising and has shown great potential in many complex tasks; however, its lack of safety guarantees limits its real-world applicability. Hence, further advancing reinforcement learning, especially from the safety perspective, is of great importance for autonomous driving. As revealed by cognitive neuroscientists, the amygdala of the brain can elicit defensive responses against threats or hazards, which is crucial for survival in and adaptation to risky environments. Drawing inspiration from this scientific discovery, we present a fear-neuro-inspired reinforcement learning framework to realize safe autonomous driving through modeling the amygdala functionality. This new technique facilitates an agent to learn defensive behaviors and achieve safe decision making with fewer safety violations. Through experimental tests, we show that the proposed approach enables the autonomous driving agent to attain state-of-the-art performance compared to the baseline agents and perform comparably to 30 certified human drivers, across various safety-critical scenarios. The results demonstrate the feasibility and effectiveness of our framework while also shedding light on the crucial role of simulating the amygdala function in the application of reinforcement learning to safety-critical autonomous driving domains

Correlating spectral and timing properties in the evolving jet of the micro blazar MAXI J1836-194

During outbursts, the observational properties of black hole X-ray binaries (BHXBs) vary on timescales of days to months. These relatively short timescales make these systems ideal laboratories to probe the coupling between accreting material and outflowing jets as a the accretion rate varies. In particular, the origin of the hard X-ray emission is poorly understood and highly debated. This spectral component, which has a power-law shape, is due to Comptonisation of photons near the black hole, but it is unclear whether it originates in the accretion flow itself, or at the base of the jet, or possibly the interface region between them. In this paper we explore the disk-jet connection by modelling the multi-wavelength emission of MAXI J1836-194 during its 2011 outburst. We combine radio through X-ray spectra, X-ray timing information, and a robust joint-fitting method to better isolate the jet's physical properties. Our results demonstrate that the jet base can produce power-law hard X-ray emission in this system/outburst, provided that its base is fairly compact and that the temperatures of the emitting electrons are sub-relativistic. Because of energetic considerations, our model favours mildly pair-loaded jets carrying at least 20 pairs per proton. Finally, we find that the properties of the X-ray power spectrum are correlated with the jet properties, suggesting that an underlying physical process regulates both.Comment: 17 pages, 10 figures, accepted for publication on MNRA

A008 Presence of tissue factor and other components of atherosclerosis in human aortic valve stenosis

BackgroundIt is now generally accepted that calcific aortic valve disease is an atherosclerotic-like process. Recent studies in an experimental model of aortic valve sclerosis demonstrated the presence of tissue factor (TF), the main contributor to atherosclerotic plaque thrombogenicity, in diseased valve leaflets. We assessed the hypothesis that human aortic valve disease is an atherosclerotic-like process in which TF plays an important role and evaluated the valvular expression and localization of TF and other components of atherosclerosis.MethodsCalcified aortic valves (n=52) were obtained from patients undergoing aortic valve replacement. Leaflet structure, cellular and lipid infiltration and expression of TF, its inhibitors, VEGF and other components of atherosclerosis were evaluated by histological and immunohistochemical staining. TF, TFPI, osteopontin, MMP- 9, TIMP-1 and VEGF antigen were measured by ELISA and TF and alkaline phosphatase activity were determined using chromogenic assays. Finally, we performed semi-quantification of TF transcripts by RT- PCR and further analyzed protein expression by Western blot.ResultsHistological and immunohistochemical staining of the valve leaflets revealed neovascularisation at the centre of the lesions, overall macrophage and myofibroblast infiltration and the abundant presence of MMP-9. On the other hand, TF and TFPI were associated with calcification and extracellular lipid deposits in the fibrosa and the subendothelial layer of the aortic side of the leaflets. Correspondingly, TF antigen and activity were found to be higher in calcified regions of the valve leaflets (733.29±70.49pg/mgvs 429.40±73.17pg/mg and 144.75±14.65pg/mgvs 40.15±6.19pg/mg respectively (p<0.0001)). Similar results were found for osteopontin, MMP-9, TIMP-1 and VEGF. In contrast, TFPI antigen was found to be much lower in these calcified regions (722.54±153.92pg/mgvs 2459.28±285.36pg/mg (p<0.0001)).ConclusionThese results demonstrate that aortic valve lesions display several characteristics of atherosclerosis, including TF expression. In addition, we showed that TF is colocalized with calcification and lipid deposition. Further studies are now set up to evaluate the role of TF in aortic valve disease and its association with other components of the atherosclerotic process

Peering at the outflow mechanisms in the transitional pulsar PSR J1023+0038: simultaneous VLT, XMM-Newton, and Swift high-time resolution observations

We report on a NIR, optical and X-ray campaign performed in 2017 with the XMM-Newton and Swift satellites and the VLT/HAWK-I instrument on the transitional MSP PSR J1023+0038. NIR observations were performed in fast-photometric mode in order to detect any fast variation of the flux and correlate them with the optical and X-ray light curves. The optical curve shows the typical sinusoidal modulation at the orbital period (4.75hr). No flaring or flickering is found in the optical, neither signs of transitions between active and passive states. On the contrary, the NIR curve displays a bimodal behaviour, showing strong flares in the first part of the curve, and an almost flat trend in the rest. The X-ray curves show a few low/high mode transitions, but no flaring activity. One of the low/high mode transition is found to happen at the same time as the emission of an infrared flare. This can be interpreted as the emission of a jet: the NIR flare could be due to the evolving spectrum of the jet, which possesses a break frequency that moves from higher (NIR) to lower (radio) frequencies after the launching, that has to happen at the low/high mode transition. We also present the cross correlation function between the optical and near infrared curves. Due to the bimodality of the NIR curve, we divided it in two parts (flaring and quiet). While the CCF of the quiet part is found to be flat, the one referring to the flaring part shows a narrow peak at ~10s, which indicates a delay of the NIR emission with respect to the optical. This lag can be interpreted as reprocessing of the optical emission at the light cylinder radius with a stream of matter spiraling around the system due to a phase of radio-ejection. This strongly supports a different origin of the NIR flares observed for PSR J1023+0038 with respect to the optical and X-ray flaring activity reported in other works on the same source.Comment: 10 pages, 9 figures. Accepted for publication in Astronomy&Astrophysic

An underlying clock in the extreme flip-flop state transitions of the black hole transient Swift J1658.2-4242

Aims: Flip-flops are top-hat-like X-ray flux variations which occur in some transient accreting black hole binary systems and feature simultaneous changes in the spectral hardness and the Power Density Spectrum (PDS). They occur at a crucial time in the evolution of these systems, when the accretion disk emission starts to dominate over coronal emission. Flip-flops have only rarely been observed and are poorly understood. Methods: We detect 15 flip-flops in the 2018 outburst of Swift J1658.2-4242, in observations by XMM-Newton, NuSTAR, Astrosat, Swift, Insight-HXMT, INTEGRAL, and ATCA. We analyse their light curves, search for periodicities, compute their PDS, and fit their X-ray spectra, to investigate the source behaviour during flip-flop transitions, and how the interval featuring flip-flops differs from the rest of the outburst. Results: The flip-flops of Swift J1658.2-4242 are of an extreme variety, exhibiting flux differences of up to 77% within ~100s, much larger than has been seen so far. We observe radical changes in the PDS simultaneous with the sharp flux variations, featuring transitions between the Quasi-Periodic Oscillation types C and A, which have never been observed before. Changes to the PDS are delayed, but more rapid than changes in the light curve. Flip-flops occur in two intervals, separated by two weeks in which these phenomena were not seen. Transitions between the two flip-flop states occurred at random integer multiples of a fundamental period, of 2.761ks in the first interval, and 2.61ks in the second. Spectral analysis reveals the high and low flux flip-flop states to be similar, but distinct from intervals lacking flip-flops. A change in the inner temperature of the accretion disk is responsible for most of the flux difference in the flip-flops. We highlight the importance of correcting for the influence of the dust scattering halo on the X-ray spectra.Comment: 30 pages, 28 figures, accepted for publication in Astronomy & Astrophysic

Low power coordination in wireless ad-hoc networks

ABSTRACT Distributed wireless ad-hoc networks @WANs) pose numerous technical Among them, two are widely conthese problems, two are of dominating importance: (i) low energy and Operation and (ii) autonomous localized operation and decision making. Recent studies have shown sidered as crucial: autonomous localized operation and minimization of energy consumption. We address the fundamental problem of how to maximize life-time of the network by using only local information while preserving network connectivity, We start by introducing the Care-Ree Sleep (CS) Theorem that provides provably optimal necessary and nodes are not required for addressing the current network cient conditions for a node to turn off its radio while ensuring and Although there have been a number of efforts to deterthat global connectivity is not affected. The cS theorem is the basis for an efficient localized almine the conditions for a node to enter sleep state using gorithm that decides which node will turn its radio off, and only locally available information while preserving the overfor how long, The effectiveness of the approach is demonall connectivity of the network, only heuristic answers have sleep coordination problem. The sleep coordination problem the algorithm over a wide range of network parameters. is interesting and challenging from several view points: 0 Complexity of the Problem. The nodes that stay Categories and Subject Descriptors awake to preserve the connectivity of the network form a [ C O M P U T E R -C O M M U N I C A T I O N N E T W O R K S ] : connected dominating set on the network graph. Finding Network Protocols; C.4 [ P E R F O R M A N C E OF S Y S - the minimum connected dominating set can be proven to be TEMS]: [Reliability, availability, and serviceability] NP-complete. Therefore, even in cases where we do have the complete graph information about the whole network, finding the optimal solution in polynomial time is unlikely. Furthermore, setting the proper sleep times t o the nodes to maximize the overall network&apos;s lifetime, adds a new dimension to the NP-complete minimum connected dominating 0 Scope of the Problem. For a sleep coordination procedure, making a globally sound decision using only local information is a challenging task. Changing the status of even one node can potentially impact any node in the network ill terms Of its CODneCtiVity and energy consumption. 0 Guaranteed Connectivity. There is a need to determine under which conditions, a Particular node can sleep, while still guaranteeing that the network is connected. 0 Protocol Design. The autonomous operation of the nodes in DWANs has several advantages including fault tolerance, fast response to changes, and non-PrePlanned network structure. However, interaction and collaboration between the nodes and existence of shared resources, dictates a need for a protocol that can handle concurrency and synchronization of the autonomous ad-hoc node decisions. The power saving coordination strategy introduced here attempts to address these challenges. we start by introducing the care-nee sleep (CS) theorem that establishes provably optimal necessary and sufficient conditions for a given node to enter sleep state without disconnecting the network. strated using numerous simulations of the performance of been Presented [17, 3~ &apos; 1. we refer to this Problem as the General Terms Algorithms, Design, Performance Keywords set problem. Wireless ad-hoc network, low-power, coordinatio

Engineering change in a non-deterministic FSM setting

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