Paul Sabatier University

About: Paul Sabatier University is a education organization based out in Toulouse, France. It is known for research contribution in the topics: Population & Adipose tissue. The organization has 15431 authors who have published 23386 publications receiving 858364 citations.

Evidence for water ice near Mercury's north pole from MESSENGER Neutron Spectrometer measurements.

Abstract: Measurements by the Neutron Spectrometer on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft show decreases in the flux of epithermal and fast neutrons from Mercury’s north polar region that are consistent with the presence of water ice in permanently shadowed regions. The neutron data indicate that Mercury’s radar-bright polar deposits contain, on average, a hydrogen-rich layer more than tens of centimeters thick beneath a surficial layer 10 to 30 cm thick that is less rich in hydrogen. Combined neutron and radar data are best matched if the buried layer consists of nearly pure water ice. The upper layer contains less than 25 weight % water-equivalent hydrogen. The total mass of water at Mercury’s poles is inferred to be 2 × 1016 to 1018 grams and is consistent with delivery by comets or volatile-rich asteroids.

Conditioning procedure and color discrimination in the honeybee Apis mellifera.

Abstract: We studied the influence of the conditioning procedure on color discrimination by free-flying honeybees. We asked whether absolute and differential conditioning result in different discrimination capabilities for the same pairs of colored targets. In absolute conditioning, bees were rewarded on a single color; in differential conditioning, bees were rewarded on the same color but an alternative, non-rewarding, similar color was also visible. In both conditioning procedures, bees learned their respective task and could also discriminate the training stimulus from a novel stimulus that was perceptually different from the trained one. Discrimination between perceptually closer stimuli was possible after differential conditioning but not after absolute conditioning. Differences in attention inculcated by these training procedures may underlie the different discrimination performances of the bees.

TNFα up-regulates apelin expression in human and mouse adipose tissue

Abstract: We have recently identified apelin as a novel adipokine up-regulated by insulin and obesity. Since obesity and insulin resistance are associated with chronically elevated levels of both insulin and TNFalpha, the present study was performed to investigate a putative regulation of apelin expression in adipocytes by TNFalpha. Herein, we report a tight correlation between apelin and TNFalpha expression in adipose tissue of lean and obese humans. Apelin regulation by TNFalpha was further studied in cultured explants of human adipose tissue. The endogenous expression of TNFalpha in adipocytes isolated from the explants was accompanied by a 6-9 h subsequent increase of apelin expression in adipocytes. This increase was reversed by inhibiting TNFalpha expression with 100 microM isobutylmethylxanthine. In different mouse models of obesity, expression of both TNFalpha and apelin was also significantly increased in adipocytes of obese mice. Furthermore, short-term exposure to an i.p. injection of TNFalpha in C57Bl6/J mice induced an increase of apelin expression in adipose tissue as well as apelin plasma levels. Finally, a direct positive effect of TNFalpha has been shown in differentiated 3T3F442A adipocytes on apelin expression and secretion. The signaling pathways of TNFalpha for the induction of apelin were dependent of PI3-kinase, c-Jun NH2-terminal kinase (JNK), and MAPK but not PKC activation. All together, these findings suggest that apelin might be a candidate to better understand potential links between obesity and associated disorders such as inflammation and insulin resistance.

Airy Distribution Function: From the Area Under a Brownian Excursion to the Maximal Height of Fluctuating Interfaces

Abstract: The Airy distribution function describes the probability distribution of the area under a Brownian excursion over a unit interval. Surprisingly, this function has appeared in a number of seemingly unrelated problems, mostly in computer science and graph theory. In this paper, we show that this distribution function also appears in a rather well studied physical system, namely the fluctuating interfaces. We present an exact solution for the distribution P(h m ,L) of the maximal height h m (measured with respect to the average spatial height) in the steady state of a fluctuating interface in a one dimensional system of size L with both periodic and free boundary conditions. For the periodic case, we show that P(h m ,L)=L−1/2f(h m L−1/2) for all L>0 where the function f(x) is the Airy distribution function. This result is valid for both the Edwards–Wilkinson (EW) and the Kardar–Parisi–Zhang interfaces. For the free boundary case, the same scaling holds P(h m ,L)=L−1/2F(h m L−1/2), but the scaling function F(x) is different from that of the periodic case. We compute this scaling function explicitly for the EW interface and call it the F-Airy distribution function. Numerical simulations are in excellent agreement with our analytical results. Our results provide a rather rare exactly solvable case for the distribution of extremum of a set of strongly correlated random variables. Some of these results were announced in a recent Letter [S.N. Majumdar and A. Comtet, Phys. Rev. Lett. 92: 225501 (2004)].