Hybridizing matter-wave and classical accelerometers

We demonstrate a hybrid accelerometer that benefits from the advantages of both conventional and atomic sensors in terms of bandwidth (DC to 430 Hz) and long term stability. First, the use of a real time correction of the atom interferometer phase by the signal from the classical accelerometer enables to run it at best performances without any isolation platform. Second, a servo-lock of the DC component of the conventional sensor output signal by the atomic one realizes a hybrid sensor. This method paves the way for applications in geophysics and in inertial navigation as it overcomes the main limitation of atomic accelerometers, namely the dead times between consecutive measurements

Real-time vibration rejection in an absolute atomic gravimeter

International audienc

Real-time vibration rejection in an absolute atomic gravimeter

International audienc

Optimal Denial-of-Service Attack Scheduling with Energy Constraint over Packet-Dropping Networks

The recent years have seen a surge of security issues of cyber-physical systems (CPS). In this paper, denial-of-service (DoS) attack scheduling is investigated in depth. Specifically, we consider a system where a remote estimator receives the data packet sent by a sensor over a wireless network at each time instant, and an energy-constrained attacker that cannot launch DoS attacks all the time designs the optimal DoS attack scheduling to maximize the attacking effect on the remote estimation performance. Most of the existing works concerning DoS attacks focus on the ideal scenario in which data packets can be received successfully if there is no DoS attack. To capture the unreliability nature of practical networks, we study the packet-dropping network in which packet dropouts may occur even in the absence of attack. We derive the optimal attack scheduling scheme that maximizes the average expected estimation error, and the one which maximizes the expected terminal estimation error over packet-dropping networks. We also present some countermeasures against DoS attacks, and discuss the optimal defense strategy, and how the optimal attack schedule can serve for more effective and resource-saving countermeasures. We further investigate the optimal attack schedule with multiple sensors. The optimality of the theoretical results is demonstrated by numerical simulations

Guided Assembly of Tetramolecular G-Quadruplexes

Nucleic acids are finding applications in nanotechnology as nanomaterials, mechanical devices, templates, and biosensors. G-quadruplex DNA, formed by pi-pi stacking of guanine (G) quartets, is an attractive alternative to regular B-DNA because of the kinetic and thermodynamic stability of quadruplexes. However, they suffer from a fatal flaw: the rules of recognition, i.e., the formation of a G-quartet in which four identical bases are paired, prevent the controlled assembly between different strands, leading to complex mixtures. In this report, we present the solution to this recognition problem. The proposed design combines two DNA elements: parallel-stranded duplexes and a quadruplex core. Parallel-stranded duplexes direct controlled assembly of the quadruplex core, and their strands present convenient points of attachments for potential modifiers. The exceptional stability of the quadruplex core provides integrity to the entire structure, which could be used as a building block for nucleic acid-based nanomaterials. As a proof of principle for the design\u27s versatility, we assembled quadruplex-based 10 structures and visualized them using atomic force and transmission electron microscopy. Our findings pave the way to broader utilization of G-quadruplex DNA in structural DNA nanomaterials