Persistent coordination patterns in a complex task after 10 years delay

The aim of this experiment was to examine the qualitative behavioral reorganizations of a complex skill acquisition on a ski-simulator that occur after a long term delay. 10 years before, five subjects practiced for 39 sessions of ten 1-min trials on a modified version of the ski-simulator. In the present study, a retention test (10 years after) was conducted for 1 session of ten 1-min trials, with the same subjects in the same conditions. Analyses focused on the motion of the apparatus platform modeled as a self-sustained oscillator. At the beginning of the experiment, all subjects adopted a behavior that could be modeled with a moderate non-linear stiffness function, a van der Pol damping function, a frequency and amplitude values under the previous experiment. In the final part of the experiment we observed: a linear stiffness function, a van der Pol damping behaviour and frequency and amplitude values near but always under the previous study. The results indicate that the acquisition of expert pattern behaviour persists well over a long delay

Hyperspectral Computed Tomographic Imaging Spectroscopy of Vascular Oxygen Gradients in the Rabbit Retina In Vivo

Diagnosis of retinal vascular diseases depends on ophthalmoscopic findings that most often occur after severe visual loss (as in vein occlusions) or chronic changes that are irreversible (as in diabetic retinopathy). Despite recent advances, diagnostic imaging currently reveals very little about the vascular function and local oxygen delivery. One potentially useful measure of vascular function is measurement of hemoglobin oxygen content. In this paper, we demonstrate a novel method of accurately, rapidly and easily measuring oxygen saturation within retinal vessels using in vivo imaging spectroscopy. This method uses a commercially available fundus camera coupled to two-dimensional diffracting optics that scatter the incident light onto a focal plane array in a calibrated pattern. Computed tomographic algorithms are used to reconstruct the diffracted spectral patterns into wavelength components of the original image. In this paper the spectral components of oxy- and deoxyhemoglobin are analyzed from the vessels within the image. Up to 76 spectral measurements can be made in only a few milliseconds and used to quantify the oxygen saturation within the retinal vessels over a 10–15 degree field. The method described here can acquire 10-fold more spectral data in much less time than conventional oximetry systems (while utilizing the commonly accepted fundus camera platform). Application of this method to animal models of retinal vascular disease and clinical subjects will provide useful and novel information about retinal vascular disease and physiology

Humanités Numériques et Pensée complexe

International audienc

Humanités Numériques et Pensée complexe

International audienc

Persistent coordination patterns in a complex task after 10 years delay

The aim of this experiment was to examine the qualitative behavioral reorganizations of a complex skill acquisition on a ski-simulator that occur after a long term delay. 10 years before, five subjects practiced for 39 sessions of ten 1-min trials on a modified version of the ski-simulator. In the present study, a retention test (10 years after) was conducted for 1 session of ten 1-min trials, with the same subjects in the same conditions. Analyses focused on the motion of the apparatus platform modeled as a self-sustained oscillator. At the beginning of the experiment, all subjects adopted a behavior that could be modeled with a moderate non-linear stiffness function, a van der Pol damping function, a frequency and amplitude values under the previous experiment. In the final part of the experiment we observed: a linear stiffness function, a van der Pol damping behaviour and frequency and amplitude values near but always under the previous study. The results indicate that the acquisition of expert pattern behaviour persists well over a long delay

Les fonctions sociales du commérage et le modèle Leviathan

International audienceIn this paper, we are interested in understanding the relation between gossip and two social phenomena: consensus and the positivity bias. These two properties of a population together seem somewhat counterintuitive: a population needs some consensus to act as a group, at the same time the positivity bias is said to be quite universal and it means people diverge. This paradox can perhaps be solved by the understanding of its links to gossip and its social functions (Foster, 2004). Deffuant, Carletti, and Huet (2013) have shown that the Leviathan model is able to exhibit these two social phenomena. They emerge from the individual’s need to form a valuation of themselves (i.e. self-valuation), as well as defining the value of others, through direct interaction and gossip. The particular role of gossip in their emergence and maintenance has not been exhaustively investigated in this model. That is the purpose of this paper, which starts from four hypotheses: gossip leads to consensus which increases with its intensity; gossip decreases the strength of the positivity bias and can suppress it; positivity bias and disagreement are linked to each other; the positivity bias and bias to negativity occurring in the Leviathan model appear conjointly whatever the level of gossip (they have been conjointly diagnosed in the first investigations of Deffuant et al. 2013). Overall, our hypotheses are confirmed. We especially find that consensus is almost never reached without gossip. We also show how an asymmetrical level of openness to the influence of others, depending on how high they are held in esteem, is important for the positivity bias, as well as for the bias to negativity. The number of peers discussed during a meeting is also shown to be essential for consensus