Regulation of hepatic metabolism by AMPK.

3 pagesInternational audiencen.

Discreteness Unravels the Black Hole Information Puzzle: Insights from a Quantum Gravity Toy Model

The black hole information puzzle can be resolved if two conditions are met. Firstly, if the information of what falls inside a black hole remains encoded in degrees of freedom that persist after the black hole completely evaporates. These degrees of freedom should be capable of purifying the information. Secondly, if these purifying degrees of freedom do not significantly contribute to the system's energy, as the macroscopic mass of the initial black hole has been radiated away as Hawking radiation to infinity. The presence of microscopic degrees of freedom at the Planck scale provides a natural mechanism for achieving these two conditions without running into the problem of the large pair-creation probabilities of standard remnant scenarios. In the context of Hawking radiation, the first condition implies that correlations between the 'in' and 'out' Hawking partner particles need to be transferred to correlations between the microscopic degrees of freedom and the 'out' partners in the radiation. This transfer occurs dynamically when the 'in' partners reach the singularity inside the black hole, entering the UV regime of quantum gravity where the interaction with the microscopic degrees of freedom becomes strong. The second condition suggests that the conventional notion of the vacuum's uniqueness in quantum field theory should fail when considering the full quantum gravity degrees of freedom. In this paper, we demonstrate both key aspects of this mechanism using a solvable toy model of a quantum black hole inspired by loop quantum gravity.Comment: arXiv admin note: text overlap with arXiv:2301.03951, arXiv:1703.0914

Feed-forward and visual feedback control of head roll orientation in wasps (Polistes humilis, Vespidae, Hymenoptera)

Flying insects keep their visual system horizontally aligned, suggesting that gaze stabilization is a crucial first step in flight control. Unlike flies, hymenopteran insects such as bees and wasps do not have halteres that provide fast, feed-forward ang

Bio-Inspired Hovering Control for an Aerial Robot Equipped with a Decoupled Eye and a Rate Gyro

International audienceThis work provides an hovering control strategy for a sighted robot, the eye of which being decoupled from the body and controlled by means of a tiny rotative piezo motor. The main purpose of this paper is to show the effectiveness and the efficiency of this fundamental bio-inspired mechanical decoupling. Indeed, it exhibits several benefits: * it enables to stabilize the robot's gaze on the basis of three bio-inspired oculomotor reflexes (ORs) : a visual fixation reflex (VFR), a translational and rotational vestibulo- ocular reflexes (tVOR and rVOR), * the eye can better, quickly and accurately compensate for sudden, untoward disturbances caused by the vagaries of the supporting head or body, * it yields a reference visual signal that can be used to unbias the rate gyro used to implement the VORs and to stabilize the hovering robot, * it increases the tracking accuracy with moving targets compared to without OR, This paper shows also that lateral disturbances are rejected 2 times faster with the decoupled eye robot, and roll perturbations induce a retinal error 20 times smaller. The occulomotor reflexes enables to cancel retinal error 6 times faster with 5 times lower retinal error picks. The conclusion of the paper is that decoupled eye must be considered as an efficient autonomous flight solution

Bypassing AMPK Phosphorylation

International audienceAMP-activated protein kinase (AMPK) functions as a signaling hub to balance energy supply with demand. Phosphorylation of activation loop Thr172 has been considered as an essential step in AMPK activation. In this issue of Chemistry & Biology, Scott and colleagues show that the small molecule direct AMPK activator, A-769662, bypasses this phosphorylation event, and acts synergistically with AMP on naive AMPK

Steering by Gazing: An Efficient Biomimetic Control Strategy for Visually-guided Micro-Air Vehicles

International audienceOSCAR 2 is a twin-engine aerial demonstrator equipped with a monocular visual system, which manages to keep its gaze and its heading steadily fixed on a target (a dark edge or a bar) in spite of the severe random perturbations applied to its body via a ducted fan. The tethered robot stabilizes its gaze on the basis of two Oculomotor Reflexes (ORs) inspired by studies on animals: - a Visual Fixation Reflex (VFR) - a Vestibulo-ocular Reflex (VOR) One of the key features of this robot is the fact that the eye is decoupled mechanically from the body about the vertical (yaw) axis. To meet the conflicting requirements of high accuracy and fast ocular responses, a miniature (2.4-gram) Voice Coil Motor (VCM) was used, which enables the eye to make a change of orientation within an unusually short rise time (19ms). The robot, which was equipped with a high bandwidth (7Hz) "Vestibulo-Ocular Reflex (VOR)" based on an inertial micro-rate gyro, is capable of accurate visual fixation as long as there is light. The robot is also able to pursue a moving target in the presence of erratic gusts of wind. Here we present the two interdependent control schemes driving the eye in the robot and the robot in space without any knowledge of the robot's angular position. This "steering by gazing" control strategy implemented on this lightweight (100-gram) miniature aerial robot demonstrates the effectiveness of this biomimetic visual/inertial heading control strategy

A mouse sensor and a 2-pixel motion sensor exposed to continuous illuminance changes

International audienceConsiderable attention has been paid during the last decade to navigation systems based on the use of visual optic flow cues, especially for guiding autonomous robots designed to travel under specific lighting conditions. In the present study, the performances of two visual motion sensors used to measure a local 1-D angular speed, namely (i) a bio-inspired 2-pixel motion sensor and (ii) an off-the-shelf mouse sensor, were tested for the first time in a wide range of illuminance levels. The sensors' characteristics were determined here by recording their responses to a purely rotational optic flow generated by rotating the sensors mechanically and comparing their responses with an accurate rate gyro output signal. The refresh rate, a key parameter for future optic flow-based robotic applications, was also defined and tested in these two sensors. The bio-inspired 2-pixel motion sensor was found to be more accurate indoors whereas the mouse sensor was found to be more efficient outdoors