Collège de France

About: Collège de France is a education organization based out in Paris, France. It is known for research contribution in the topics: Population & Receptor. The organization has 6541 authors who have published 11983 publications receiving 648742 citations. The organization is also known as: College de France.

Dynamic representations underlying symbolic and nonsymbolic calculation: evidence from the operational momentum effect.

Abstract: When we add or subtract, do the corresponding quantities “move” along a mental number line? Does this internal movement lead to spatial biases? A new method was designed to investigate the psychophysics of approximate arithmetic. Addition and subtraction problems were presented either with sets of dots or with Arabic numerals, and subjects selected, from among seven choices, the most plausible result. In two experiments, the subjects selected larger numbers for addition than for subtraction problems, as if moving too far along the number line. This operational momentum effect was present in both notations and increased with the size of the outcome. Furthermore, we observed a new effect of spatial-numerical congruence, related to but distinct from the spatial numerical association of response codes effect: During nonsymbolic addition, the subjects preferentially selected numbers at the upper right location, whereas during subtraction, they were biased toward the upper left location. These findings suggest that approximate mental arithmetic involves dynamic shifts on a spatially organized mental representation of numbers. Supplemental materials for this study may be downloaded from app.psychonomic-journals.org/content/supplemental.

Experiments on wetting on the scale of nanometers: Influence of the surface energy.

Abstract: Via ellipsometry, the time-dependent profiles of liquid droplets spreading completely on plane solid substrates are measured in the range 0--200 \AA{} Two different surfaces are used, a ``high-energy'' surface (wettable by water) and a ``low-energy'' surface (Langmuir-Blodgett layer of a double-bond-terminated fatty acid), respectively We have observed that the shape of spreading droplets of the same fluid (polydimethylsiloxane) are quite different on these two surfaces: On the low-energy surface, the spreading occurs by the macroscopic lateral spreading of essentially one monolayer, away from the central part of the drop On the contrary, for the high-energy surface, spreading occurs by the macroscopic lateral spreading of several monolayers in a kind of hierarchical process Nevertheless, in both cases there is a signature of molecular structuring in the fluid flow at the center of the drop

Polymodal activation of the endocannabinoid system in the extended amygdala

Abstract: The reason why neurons synthesize more than one endocannabinoid (eCB) and how this is involved in the regulation of synaptic plasticity in a single neuron is not known. We found that 2-arachidonoylglycerol (2-AG) and anandamide mediate different forms of plasticity in the extended amygdala of rats. Dendritic L-type Ca(2+) channels and the subsequent release of 2-AG acting on presynaptic CB1 receptors triggered retrograde short-term depression. Long-term depression was mediated by postsynaptic mGluR5-dependent release of anandamide acting on postsynaptic TRPV1 receptors. In contrast, 2-AG/CB1R-mediated retrograde signaling mediated both forms of plasticity in the striatum. These data illustrate how the eCB system can function as a polymodal signal integrator to allow the diversification of synaptic plasticity in a single neuron.

Scaling Description of Two-Dimensional Chain Conformations in Polymer Monolayers

Abstract: It is shown how the molecular weight dependence of the radius of gyration ${R}_{F2}$ of two-dimensional polymeric chains can be derived from surface-pressure isotherms in Langmuir monolayers. ${R}_{F2}$ scales as ${N}^{\ensuremath{ u}}$ with $\ensuremath{ u}=0.56$ for polymethylmethacrylate and 0.79 for polyvinylacetate. These values are in agreement with the scaling predictions for tricritical and excluded-volume behaviors, respectively. The crossover between the dilute and the intermediate regimes is also clearly observed in one case.