Effects of pyruvate administration on infarct volume and neurological deficits following permanent focal cerebral ischemia in rats

Recent experimental evidences indicate that pyruvate, the final metabolite of glycolysis, has a remarkable protective effect against different types of brain injury. The purpose of this study was to assess the neuroprotective effect and the neurological outcome after pyruvate administration in a model of ischemic stroke induced by permanent middle cerebral artery occlusion (pMCAO) in rats. Three doses of pyruvate (250, 500 and 1000 mg/kg, i.p.) or vehicle were administered intraperitoneally 30 min after pMCAO. In other set of experiments, pyruvate was given either before, immediately after ischemia or in a long-term administration paradigm. Functional outcome, mortality and infarct volume were determined 24 h after stroke. Even when the lowest doses of pyruvate reduced mortality and neurological deficits, no concomitant reduction in infarct volume was observed. The highest dose of pyruvate increased cortical infarction by 27% when administered 30 min after pMCAO. In addition, when pyruvate was given before pMCAO, a significant increase in neurological deficits was noticed. Surprisingly, on the contrary of what was found in the case of transient global ischemia, present findings do not support a great neuroprotective role for pyruvate in permanent focal cerebral ischemia, suggesting two distinct mechanisms involved in the effects of this glycolytic metabolite in the ischemic brain

Autonomous coalitions

We consider in this paper solutions for TU-games where it is not assumed that the grand coalition is necessarily the final state of cooperation. Partitions of the grand coalition, or balanced collections together with a system of balancing weights interpreted as a time allocation vector are considered as possible states of cooperation. The former case corresponds to the c-core, while the latter corresponds to the aspiration core or d-core, where in both case, the best configuration (called a maximising collection) is sought. We study maximising collections and characterize them with autonomous coalitions, that is, coalitions for which any solution of the d-core yields a payment for that coalition equal to its worht. In particular we show that the collection of autonomous coalitions is balanced, and that one cannot have at the same time a single possible payment (core element) and a single possible configuration. We also introduce the notion of inescapable coalitions, that is, those present in every maximising collection. We characterize the class of games for which the sets of autonomous coalitions, vital coalitions (in the sense of Shellshear and Sudhölter), and inescapable coalitions coincide, and prove that the set of games having a unique maximising coalition is dense in the set of games.Dans cet article, nous étudions des solutions de jeux coopératifs à utilité transférable où il n'est pas requis que la grande coalition soit nécessairement l'état final de coopération. On suppose que les joueurs peuvent jouer en partition ou en collection équilibrée de la grande coalition : dans ce dernier cas le poids associé à chaque coalition est interprété comme une allocation de temps. On étudie en particulier quelles sont les meilleures configurations pour les joueurs, c'est-à-dire quelles sont les coalitions générant le c-coeur dans le cas où les joueurs jouent en partition, ou le d-coeur sinon. Nous appelons collections maximisantes ces meilleures configurations, nous les étudions et les caractérisons par les coalitions autonomes, c'est-à-dire par les coalitions dont la valeur est égale à n'importe quel paiement donné par le d-coeur. Nous montrons qu'il existe toujours de telles coalitions, et qu'elles forment une collection équilibrée quel que soit le jeu. Nous montrons que pour les jeux équilibrés, il n'est pas possible d'avoir en même temps une unique collection maximisante et un unique paiement (cœur réduit à la singleton). Nous introduisons pour un jeu quelconque la notion de coalition incontournable : coalition se trouvant dans toute collection maximisante, nous caractérisons l'ensemble des jeux pour lesquels les coalitions vitales introduites par Shellshear et Sudhölter, les coalitions autonomes et les coalitions incontournables coïncident. Nous prouvons enfin que l'ensemble des jeux possédant une unique collection maximisante est dense dans l'ensemble des jeux

Multicoalitional solutions

Documents de travail du Centre d'Economie de la Sorbonne 2013.62 - ISSN : 1955-611XThe paper proposes a new concept of solution for TU games, called multicoalitional solution, which makes sense in the context of production games, that is, where v(S) is the production or income per unit of time. By contrast to classical solutions where elements of the solution are payoff vectors, multicoalitional solutions give in addition an allocation time to each coalition, which permits to realize the payoff vector. We give two instances of such solutions, called the d-multicoalitional core and the c-multicoalitional core, and both arise as the strong Nash equilibrium of two games, where in the first utility per active unit of time is maximized, while in the second it is the utility per total unit of time. We show that the d-core (or aspiration core) of Benett, and the c-core of Guesnerie and Oddou are strongly related to the d-multicoalitional and c-multicoalitional cores, respectively, and that the latter ones can be seen as an implementation of the former ones in a noncooperative framework.Nous proposons dans ce papier un nouveau concept de solutions pour les jeux coopératifs à utilité transférable, que nous appelons solutions multicoalitionnelles. Ce type de solutions fera particulièrement sens pour modéliser des problèmes où la valeur d'un jeu correspondra à une quantité de biens produits par unité de temps. Contrairement au cadre classique où les vecteurs de paiements correspondent à un partage de la valeur de la grande coalition, les éléments d'une solution multicoalitionnelle indiqueront un vecteur de paiement et la durée d'activité de chaque coalition ayant permis d'engendrer ce vecteur de paiement. Nous étudions plus particulièrement deux exemples de ce type de solutions : le d-coeur multicoalitionnel et le c-coeur multicoalitionnel. Nous montrons que chacune de ces deux solutions correspond aux équilibres de Nash forts d'un jeu non coopératif très naturel pour modéliser une formation de coalitions. Une stratégie d'un joueur consiste à déclarer le temps qu'il souhaite passer dans chaque coalition et le paiement qu'il souhaite recevoir pour cela. Les équilibres de Nash forts du d-coeur multicoalitionnel sont issus du jeu ayant une utilité pour chaque joueur égale au gain par heure travaillée, tandis que les équilibres du c-coeur multicoalitionnel ayant une utilité pour chaque joueur égale au gain reçu à la fin du processus de formation coalitionnelle, c'est-à-dire au gain par heure vécue. Nous voyons enfin en quoi ces deux solutions sont fortement liées au concept de d-coeur (Bennett) et de c-coeur (Guesnerie et Oddou), et en quoi nous les implémentons dans un cadre non-coopératif

Post-ischaemic treatment with the cyclooxygenase-2 inhibitor nimesulide reduces blood-brain barrier disruption and leukocyte infiltration following transient focal cerebral ischaemia in rats

Several studies suggest that cyclooxygenase (COX)-2 plays a pivotal role in the progression of ischemic brain damage. In the present study, we investigated the effects of selective inhibition of COX-2 with nimesulide (12 mg/kg) and selective inhibition of COX-1 with valeryl salicylate (VAS, 12-120 mg/kg) on prostaglandin E2 (PGE2) levels, myeloperoxidase (MPO) activity, Evans Blue (EB) extravasation and infarct volume in a standardized model of transient focal cerebral ischemia in the rat. Postischemic treatment with nimesulide markedly reduced the increase in PGE2 levels in the ischemic cerebral cortex 24 h after stroke and diminished infarct size by 48 % with respect to vehicle-treated animals after 3 days of reperfusion. Furthermore, nimesulide significantly attenuated the blood-brain barrier (BBB) damage and leukocyte infiltration (as measured by EB leakage and MPO activity, respectively) seen at 48 h after the initial ischemic episode. These studies provide the first experimental evidence that COX-2 inhibition with nimesulide is able to limit BBB disruption and leukocyte infiltration following transient focal cerebral ischemia. Neuroprotection afforded by nimesulide is observed even when the treatment is delayed until 6 h after the onset of ischemia, confirming a wide therapeutic window of COX-2 inhibitors in experimental stroke. On the other hand, selective inhibition of COX-1 with VAS had no significant effect on the evaluated parameters. These data suggest that COX-2 activity, but not COX-1 activity, contributes to the progression of focal ischemic brain injury, and that the beneficial effects observed with non-selective COX inhibitors are probably associated to COX-2 rather than to COX-1 inhibition

The accretion disk in the post period-minimum cataclysmic variable SDSS J080434.20+510349.2

This study of SDSS0804 is primarily concerned with the double-hump shape in the light curve and its connection with the accretion disk in this bounce-back system. Time-resolved photometric and spectroscopic observations were obtained to analyze the behavior of the system between superoutbursts. A geometric model of a binary system containing a disk with two outer annuli spiral density waves was applied to explain the light curve and the Doppler tomography. Observations were carried out during 2008-2009, after the object's magnitude decreased to V~17.7(0.1) from the March 2006 eruption. The light curve clearly shows a sinusoid-like variability with a 0.07 mag amplitude and a 42.48 min periodicity, which is half of the orbital period of the system. In Sept. 2010, the system underwent yet another superoutburst and returned to its quiescent level by the beginning of 2012. This light curve once again showed a double-humps, but with a significantly smaller ~0.01mag amplitude. Other types of variability like a "mini-outburst" or SDSS1238-like features were not detected. Doppler tomograms, obtained from spectroscopic data during the same period of time, show a large accretion disk with uneven brightness, implying the presence of spiral waves. We constructed a geometric model of a bounce-back system containing two spiral density waves in the outer annuli of the disk to reproduce the observed light curves. The Doppler tomograms and the double-hump-shape light curves in quiescence can be explained by a model system containing a massive >0.7Msun white dwarf with a surface temperature of ~12000K, a late-type brown dwarf, and an accretion disk with two outer annuli spirals. According to this model, the accretion disk should be large, extending to the 2:1 resonance radius, and cool (~2500K). The inner parts of the disk should be optically thin in the continuum or totally void.Comment: 12 pages, 15 figures, accepted for publication in A&

RT-SLAM: A Generic and Real-Time Visual SLAM Implementation

This article presents a new open-source C++ implementation to solve the SLAM problem, which is focused on genericity, versatility and high execution speed. It is based on an original object oriented architecture, that allows the combination of numerous sensors and landmark types, and the integration of various approaches proposed in the literature. The system capacities are illustrated by the presentation of an inertial/vision SLAM approach, for which several improvements over existing methods have been introduced, and that copes with very high dynamic motions. Results with a hand-held camera are presented.Comment: 10 page

The mediating roles of pre-competitive coping and affective states in the relationships between coach-athlete relationship, satisfaction and attainment of achievement goals

The study is aimed to explore the relationship between coach-athlete relationship, precompetitive coping and affective states, satisfaction and attainment of achievement goals. A sample of 567 French athletes (Mage = 22.10; SD = 5.66; 377 men and 190 women) involved in 75 training groups participated in the study and completed a series of self-report measures in a temporal design with three measure points. Results of multilevel analyses revealed that the coach-athlete dyad (level 2; between-person level of analysis or training groups) and task-oriented coping (level 1; within person level of analysis or individuals) significantly predicted goal attainment (level 1). Moreover, the results of the Sobel test revealed that task-oriented coping (level 1) marginally mediated the relationship between coach-athlete dyad (level 2) and sport satisfaction (level 1). Besides, the coach-athlete dyad (level 1) and Intensity of positive affect (PA) mediated the relationship between coach-athlete dyad and goal attainment. Finally, the coach-athlete dyad (level 1) and Intensity of PA mediated the relationship between coach-athlete dyad and satisfaction (level 1). In conclusion, the display of Coach-Athlete relationship strategies may enhance higher levels of precompetitive task-oriented coping, intensity of PA, goal attainment and satisfaction. Subsequently, coaches and practitioners should focus their training on enhancing coach-athlete relationship as a crucial part of training in order to perform in competitions

Bank Value and Financial Fragility

We propose a valuation model for a bank which faces a bankruptcy risk. Banks are identified with a possibly infinite random sequence of net benefits. A bank is solvent as long as its benefits remain non-negative. To preserve distressed banks from destruction, banks will be pooled within a financial coalition. When possible, those with current positive balance sheet will refinance those in need of liquidity. Banks are refinanced to the extent that their current needs for liquidity do not exceed their expected endogenous continuation value. This value itself is affected by future refinancing possibilities. We provide a recursive formula to compute this value when there is an aggregate liquidity constraint.