Measuring the universal synchronization properties of coupled oscillators across the Hopf instability

When a driven oscillator loses phase-locking to a master oscillator via a Hopf bifurcation, it enters a bounded-phase regime in which its average frequency is still equal to the master frequency, but its phase displays temporal oscillations. Here we characterize these two synchronization regimes in a laser experiment, by measuring the spectrum of the phase fluctuations across the bifurcation. We find experimentally, and confirm numerically, that the low frequency phase noise of the driven oscillator is strongly suppressed in both regimes in the same way. Thus the long-term phase stability of the master oscillator is transferred to the driven one, even in the absence of phase-locking. The numerical study of a generic, minimal model suggests that such behavior is universal for any periodically driven oscillator near a Hopf bifurcation point.Comment: 5 pages, 5 figure

Frequency-locked chaotic opto-RF oscillator

A driven opto-RF oscillator, consisting of a dual-frequency laser (DFL) submitted to frequency-shifted feedback, is studied experimentally and numerically in a chaotic regime. Precise control of the reinjection strength and detuning permits to isolate a parameter region of bounded-phase chaos, where the opto-RF oscillator is frequency-locked to the master oscillator, in spite of chaotic phase and intensity oscillations. Robust experimental evidence of this synchronization regime is found and phase noise spectra allows to compare phase-locking and bounded-phase chaos regimes. In particular, it is found that the long-term phase stability of the master oscillator is well transferred to the opto-RF oscillator even in the chaotic regime

Excitable-like chaotic pulses in the bounded-phase regime of an opto-radiofrequency oscillator

We report theoretical and experimental evidence of chaotic pulses with excitable-like properties in an opto-radiofrequency oscillator based on a self-injected dual-frequency laser. The chaotic attractor involved in the dynamics produces pulses that, albeit chaotic, are quite regular: They all have similar amplitudes, and are almost periodic in time. Thanks to these features, the system displays properties that are similar to those of excitable systems. In particular, the pulses exhibit a threshold-like response, of well-defined amplitude, to perturbations, and it appears possible to define a refractory time. At variance with excitability in injected lasers, here the excitable-like pulses are not accompanied by phase slips.Comment: 2nd versio

A 2D nanosphere array for atomic spectroscopy

We are interested in the spectroscopic behaviour of a gas confined in a micrometric or even nanometric volume. Such a situation could be encountered by the filling-up of a porous medium, such as a photonic crystal, with an atomic gas. Here, we discuss the first step of this program, with the generation and characterization of a self-organized 2D film of nanospheres of silica. We show that an optical characterization by laser light diffraction permits to extract some information on the array structure and represents an interesting complement to electron microscopy.Comment: accept\'e pour publication \`a Annales de Physique- proceedings of COLOQ1

Dual-Frequency 780-nm Ti:Sa Laser for High Spectral Purity Tunable CW THz Generation

International audience— A two-axis, two-polarization, dual-frequency Ti:Sa laser optimized for high spectral purity CW-THz generation is demonstrated. The laser output power is 50mW. Its mean emission wavelength is optimized around 780nm in order to suit the maximum efficiency of low temperature grown GaAs photomixers. Despite the extremely wide gain bandwidth of Ti:Sa, a proper intracavity filtering design, adapted to this particular laser architecture, enables tunable and single-frequency operation of each laser mode. The resulting beatnote is shown to be tunable between DC and 1.5 THz by steps of 82GHz. Its linewidth is narrower than 30 kHz without any active stabilization or cavity insolation

Efficacy of adalimumab for the treatment of refractory paediatric acrodermatitis continua of hallopeau

Acrodermatitis continua of Hallopeau (ACH) is a rare, chronic disease characterized by acropustular eruptions predominantly involving the distal phalanges of the hands and feet with marked involvement of the nail bed. The sterile pustules may coalesce to form groups of lesions, which, over time, may spread proximally to involve the dorsal side of the hands, forearms and feet. Pustulation of the nail bed and nail matrix are often associated with onychodystrophy and even anonychia of the involved digits. Atrophic skin changes, onychodystrophy and osteolysis are frequently present, causing painful and disabling lesions

Derivation of Constraints from Machine Learning Models and Applications to Security and Privacy

This paper shows how we can combine the power of machine learning with the flexibility of constraints. More specifically, we show how machine learning models can be represented by first-order logic theories, and how to derive these theories. The advantage of this representation is that it can be augmented with additional formulae, representing constraints of some kind on the data domain. For instance, new knowledge, or potential attackers, or fairness desiderata. We consider various kinds of learning algorithms (neural networks, k-nearest-neighbours, decision trees, support vector machines) and for each of them we show how to infer the FOL formulae. Then we focus on one particular application domain, namely the field of security and privacy. The idea is to represent the potentialities and goals of the attacker as a set of constraints, then use a constraint solver (more precisely, a solver modulo theories) to verify the satisfiability. If a solution exists, then it means that an attack is possible, otherwise, the system is safe. We show various examples from different areas of security and privacy; specifically, we consider a side-channel attack on a password checker, a malware attack on smart health systems, and a model-inversion attack on a neural network

Dante's Antiutilitarianism

È opinione oggi largamente diffusa che la visione storica e politica di Dante abbia caratteri fortemente conservatori o addirittura reazionari. In sintesi, la polemica dantesca contro lʼavarizia e la cupidigia nasconderebbe un radicale rifiuto della modernità e della nuova realtà socioeconomica che si stavano affermando ai suoi tempi, in nome di un ritorno al «buon tempo antico» e al mondo immobile e chiuso della tradizione. In questo saggio intendo dimostrare, al contrario, che lʼipotesi elaborata da Dante è tuttʼaltro che conservatrice, ma propone invece un modello rivoluzionario di società fondata sui valori del dono e della caritas opposti allʼutilitarismo che fino da allora si stava imponendo come principio guida della civiltà occidentale.It is a widespread opinion that the historical and political vision of Dante has highly conservative or even reactionary characteristics. In brief, Dante's polemics against avarice and cupidity hides a radical refusal of modernity and the new socio-economic reality that was taking place in his time, in the name of a return to «good old days» and to the immobile and closed world of tradition. This article demonstrates that, on the contrary, the hypothesis elaborated by Dante was everything but conservative. He proposed, instead, a revolutionary society founded on the value of the present and of caritas, as opposed to utilitarianism that had been imposed, since then, as a guideline of Western civilization

Spotlight on dupilumab in the treatment of atopic dermatitis: Design, development, and potential place in therapy

Atopic dermatitis (AD) is among the most common inflammatory skin diseases in children and adults in industrialized countries. Up to one-third of adults (probably a smaller proportion in childhood) suffer from moderate-to-severe AD, whose recommended treatment is usually based on systemic therapies. The currently available therapeutics are limited, and AD management becomes challenging in most cases. Over the last few years, new advances in the understanding of AD pathogenic mechanisms and inflammatory pathways have led to the identification of specific therapeutic targets and new molecules have been tested. Dupilumab is a fully human monoclonal antibody directed against the IL-4 receptor α subunit that is able to block the signaling of both IL-4 and IL-13 and achieve rapid and significant improvements in adults with moderate-to-severe AD. Dupilumab is ready to inaugurate a long and promising biological target treatment option for Th2 cell-mediated atopic immune response that characterizes AD