Procédés pour l’identification de nouveaux composés activateurs des ERα dans la production du monoxyde d’azote endothélial

La présente invention décrit l\u27utilisation de composés chimiques dérivés de la delphinidine dans des procédés de criblage pour identifier des composés capables d\u27activer sélectivement le récepteur aux œ strogènes ERa, et de stimuler la production de monoxyde d\u27azote (NO) par l\u27endothélium, de tels composés pouvant être par la suite incorporés dans des compositions pharmaceutiques destinées à traiter notamment les maladies cardiovasculaires

Deletion of estrogen receptor-alpha abolishes endothelial response to wine polyphenols without affecting the main cardiovascular parameters in mice

Date du colloque : 10/2009International audienc

Collaborative Delivery with Energy-Constrained Mobile Robots

We consider the problem of collectively delivering some message from a specified source to a designated target location in a graph, using multiple mobile agents. Each agent has a limited energy which constrains the distance it can move. Hence multiple agents need to collaborate to move the message, each agent handing over the message to the next agent to carry it forward. Given the positions of the agents in the graph and their respective budgets, the problem of finding a feasible movement schedule for the agents can be challenging. We consider two variants of the problem: in non-returning delivery, the agents can stop anywhere; whereas in returning delivery, each agent needs to return to its starting location, a variant which has not been studied before. We first provide a polynomial-time algorithm for returning delivery on trees, which is in contrast to the known (weak) NP-hardness of the non-returning version. In addition, we give resource-augmented algorithms for returning delivery in general graphs. Finally, we give tight lower bounds on the required resource augmentation for both variants of the problem. In this sense, our results close the gap left by previous research.Comment: 19 pages. An extended abstract of this paper was published at the 23rd International Colloquium on Structural Information and Communication Complexity 2016, SIROCCO'1

Rendezvous of Distance-aware Mobile Agents in Unknown Graphs

We study the problem of rendezvous of two mobile agents starting at distinct locations in an unknown graph. The agents have distinct labels and walk in synchronous steps. However the graph is unlabelled and the agents have no means of marking the nodes of the graph and cannot communicate with or see each other until they meet at a node. When the graph is very large we want the time to rendezvous to be independent of the graph size and to depend only on the initial distance between the agents and some local parameters such as the degree of the vertices, and the size of the agent's label. It is well known that even for simple graphs of degree $\Delta$, the rendezvous time can be exponential in $\Delta$ in the worst case. In this paper, we introduce a new version of the rendezvous problem where the agents are equipped with a device that measures its distance to the other agent after every step. We show that these \emph{distance-aware} agents are able to rendezvous in any unknown graph, in time polynomial in all the local parameters such the degree of the nodes, the initial distance $D$ and the size of the smaller of the two agent labels $l = \min(l_1, l_2)$. Our algorithm has a time complexity of $O(\Delta(D+\log{l}))$ and we show an almost matching lower bound of $\Omega(\Delta(D+\log{l}/\log{\Delta}))$ on the time complexity of any rendezvous algorithm in our scenario. Further, this lower bound extends existing lower bounds for the general rendezvous problem without distance awareness

Laser-induced electron emission from a tungsten nanotip: identifying above threshold photoemission using energy-resolved laser power dependencies

We present an experiment studying the interaction of a strongly focused 25 fs laser pulse with a tungsten nanotip, investigating the different regimes of laser-induced electron emission. We study the dependence of the electron yield with respect to the static electric field applied to the tip. Photoelectron spectra are recorded using a retarding field spectrometer and peaks separated by the photon energy are observed with a 45 % contrast. They are a clear signature of above threshold photoemission (ATP), and are confirmed by extensive spectrally resolved studies of the laser power dependence. Understanding these mechanisms opens the route to control experiment in the strong-field regime on nanoscale objects.Comment: 9 pages, 6 figure

A general lower bound for collaborative tree exploration

We consider collaborative graph exploration with a set of $k$ agents. All agents start at a common vertex of an initially unknown graph and need to collectively visit all other vertices. We assume agents are deterministic, vertices are distinguishable, moves are simultaneous, and we allow agents to communicate globally. For this setting, we give the first non-trivial lower bounds that bridge the gap between small ($k \leq \sqrt n$) and large ($k \geq n$) teams of agents. Remarkably, our bounds tightly connect to existing results in both domains. First, we significantly extend a lower bound of $\Omega(\log k / \log\log k)$ by Dynia et al. on the competitive ratio of a collaborative tree exploration strategy to the range $k \leq n \log^c n$ for any $c \in \mathbb{N}$. Second, we provide a tight lower bound on the number of agents needed for any competitive exploration algorithm. In particular, we show that any collaborative tree exploration algorithm with $k = Dn^{1+o(1)}$ agents has a competitive ratio of $\omega(1)$, while Dereniowski et al. gave an algorithm with $k = Dn^{1+\varepsilon}$ agents and competitive ratio $O(1)$, for any $\varepsilon > 0$ and with $D$ denoting the diameter of the graph. Lastly, we show that, for any exploration algorithm using $k = n$ agents, there exist trees of arbitrarily large height $D$ that require $\Omega(D^2)$ rounds, and we provide a simple algorithm that matches this bound for all trees

Size-dependent infrared properties of MgO nanoparticles with evidence of screening effect

We have investigated the infrared (IR) absorption properties of MgO nanoparticles (NPs) with the means of molecular dynamics simulations. Several size effects have been observed. We show in particular that the absorption of IR radiation does not occur predominantly through the polariton mode but preferentially through surface modes. This enhanced surface absorption is found to result from the absence of dielectric screening of the first atomic layer of the NPs. We demonstrate concomitantly that a macroscopic description of electrodynamics is inadequate to capture these unusual IR properties

Sonic hedgehog carried by microparticles prevents angiotensin II-induced hypertension and endothelial dysfunction in mice

Microparticles (MPs) are small fragments generated from the plasma membrane after cell stimulation. Among the candidate proteins harbored by MPs, we recently showed that morphogen Sonic hedgehog is present in MPs generated from activated/apoptotic human T lymphocytes and corrects endothelial injury through nitric oxide (NO) release (Agouni et al. FASEB J 2007). The present study further investigates whether MPs bearing Shh prevent angiotensin II (Ang II)-induced hypertension and endothelial dysfunction in mice. Male Swiss mice (6–8 week old) were subcutaneously implanted with osmotic minipumps delivering Ang II (0.5 mg/kg per day) or NaCl (0.9%, control group). Systolic blood pressure and heart rate were measured daily during 21 consecutive days using tail cuff plethysmography connected to a computerized system (LE 5002 # , BIOSEB). Mice were tained for 7 days. After 7 day of minipump implantation, mice received i.v. injections of MPs (10 μg/mL) or i.p. Sonic Hedgehog receptor antagonist cyclopamine (10 mg/kg per 2 days) during 1 week prior sacrifice. Thoracic aorta was removed, cleaned of connective tissue and cut in rings (3 mm length) and mounted in a myograph to study vascular reactivity. Ang II induced a significant rise in systolic blood pressure without affecting heart rate when compared to control mice. Interestingly, MPs alone did not modify both parameters but reversed Ang II-induced hypertension. Moreover, cyclopamine prevented the effects of MPs on Ang II-induced hypertension, suggesting the involvement of a Sonic Hedgehog-dependent mechanism. In the aorta, MPs alone slightly increased the sensitivity of endothelium-dependent relaxation to acetylcholine and completely reversed the impairment of acetylcholine-induced relaxation in aorta from Ang II-infused mice. The improvement of endothelial function induced by MPs was completely prevented by cyclopamine treatment. Moreover, measurement of NO production showed that MPs alone did not modify NO production in aorta, but significantly restored its decrease in Ang II-treated mice. Altogether, these results show that MPs bearing Sonic hedgehog prevent Ang II-induced hypertension and endothelial dysfunction in aorta through a mechanism associated with Sonic hedgehog-induced NO production. These MPs may represent a new therapeutic approach in cardiovascular diseases associated with decreased NO production