Search results for "résonance"
showing 6 items of 26 documents
Electronic implementation of a non-linear oscillator subjected to noise : application to the modeling of neuronal information coding
2011
We study the nonlinear FitzHugh-Nagumo model witch describes the dynamics of excitable neural element. It is well known that this system exhibits three different possible responses. Indeed, the system can be mono-stable, oscillatory or bistable. In the oscillatory regime, the system periodically responds by generating action potential. By contrast, in the mono-stable state the system response remains constant after a transient. Under certain conditions, the system can undergo a bifurcation between the stable and the oscillatory regime via the so called Andronov-Hopf bifurcation. In this Phd thesis, we consider the FitzHugh-Nagumo model in the stable state, that is set near the Andronov-Hopf…
Rôle des antigènes tissulaires de groupes sanguins humains A, B, H et Lewis dans l'évolution des Norovirus GII.4
2011
Noroviruses are one of the leading causes of gastroenteritis worldwide. Since 2002 successive GII.4 variants have circulated in the population before being replaced every 2-3 years, which raises questions about the role of their histo-blood group antigen (HBGAs) receptors in their evolution. We analyzed the interaction between representative GII.4 variants and HBGAs and determined the role of selected amino acids (aa) in the binding profiles. By mutagenesis, we showed that there was a strict structural requirement for the aa directly implicated in HBGA bindings. The ablation of the threonine 395 residue, an epidemiological feature of the post 2002 variants, allowed to gain the capacity to b…
L'image bruissante
2019
By making a dialogue between a selection of Pía Elizondo's black-and-white photographs and Coral Bracho's poems, we propose to question the textures and rustling forms in action in the photo-poetic object a priori silent. In spite of their own technicality, these esthesic expressions engage in converging gaze and listening: words, rhythms, images of light and shadow configure landscapes of outcrops, fleeting or lasting resonances, intensities territories and thus pose the problem of the figurability of silence and its circulation in the sensitive material. Playing here with the precarious limits of seeing and saying, always in tension with what escapes them, photography and poem alternately…
Nonlinear resonances and some of their applications to information processing
2021
The study of resonance phenomena in nonlinear dynamical systems has drawn considerable attention for years. The most studied nonlinear resonance is undoubtedly the famous stochastic resonance, which consists of perturbing a nonlinear system with an appropriate amount of noise to enhance the detection of a subthreshold input signal. Since the introduction of stochastic resonance in the context of climate dynamics, it was later observed that a deterministic high frequency perturbation can replace noise leading to vibrational resonance. Even if this latter resonance was investigated in many areas of science for more than two decades now, it is still receiving attentions. It is the subject of t…
Salt release and perception in model cheeses are influenced by salt/fat contents, microstructure and salt mobility
2013
Introduction and objectivesThe health authorities recommend a reduction in salt (NaCl) and fat contents of foodstuff. Reducing such components without affecting acceptability is a major challenge, particularly because of the interactions with other ingredients such as aroma compounds. This study consisted in a multimodal approach to understand the effect of changes in composition of model cheeses on the mobility and release of sodium chloride, masticatory behaviour and saltiness perception.MethodologySix model cheeses have been formulated (three fat/protein contents, two NaCl contents). The rheological properties were analysed using uniaxial compression tests. Microstructure and homogeneity…
FORMATION OF MOLECULES IN ULTRACOLD ATOMIC GASES VIA QUASI-RESONANT FIELDS
2010
we study the nonlinear mean-field dynamics of diatomic molecule formation at coherent photo- and magneto-association of ultracold atoms focusing on the case when the system is initially in the all-atomic state. We show that in the limit of strongly nonlinear interaction between an ultra-cold atomic-molecular system and a quasi-resonant electromagnetic field, the molecule formation process, depending on the characteristics of the associating field, may evolve according two different scenarios, namely, weak- and strong-oscillatory regimes. In the first case the number of molecules increases without pronounced oscillations of atom-molecule populations, while in the second case high-amplitude R…