Nonintrusive approximation of parametrized limits of matrix power algorithms -- application to matrix inverses and log-determinants

We consider in this work quantities that can be obtained as limits of powers of parametrized matrices, for instance the inverse matrix or the logarithm of the determinant. Under the assumption of affine dependence in the parameters, we use the Empirical Interpolation Method (EIM) to derive an approximation for powers of these matrices, from which we derive a nonintrusive approximation for the aforementioned limits. We derive upper bounds of the error made by the obtained formula. Finally, numerical comparisons with classical intrusive and nonintrusive approximation techniques are provided: in the considered test-cases, our algorithm performs well compared to the nonintrusive ones

The Effect of the Euro on Aeronautic Trade: A French Regional Analysis

International audienc

Avantages comparatifs et distance, le cas de l'île de la Réunion

Avantages comparatifs et distance, le cas de l'île de la Réunion

Taux de change réel et compétitivité de l'économie réunionnaise

Taux de change réel et compétitivité de l'économie réunionnaise

Taux de change réel et compétitivité de l'économie réunionnaise

L'île de La Réunion, région française ultrapériphérique, se caractérise par des performances économiques généralement en deçà de celles de la métropole, mais aussi de celles de partenaires commerciaux qui partagent nombre de caractéristiques communes. Le très fort déficit de la balance commerciale réunionnaise en est un des révélateurs. Ceci nous conduit à étudier la compétitivité-prix de La Réunion grâce au calcul et à l'examen des propriétés statistiques de l'indicateur de taux de change effectif réel. Il ressort que ce taux est stationnaire autour d'une tendance et qu'il ne révèle pas de phénomène de surévaluation significatif. Par conséquent les piètres performances en matière de commerce extérieur ne peuvent être mises sur le compte d'un euro qui serait « trop fort », mais doivent conduirent les décideurs à réfléchir sur les causes structurelles d'un modèle économique peu performant.taux de change réel;Stationnarité;racine unitaire;la reunion

Taux de change réel et compétitivité de l’économie réunionnaise

L’île de La Réunion, région française ultrapériphérique, se caractérise par des performances économiques généralement en deçà de celles de la métropole, mais aussi de celles de partenaires commerciaux qui partagent nombre de caractéristiques communes. Le très fort déficit de la balance commerciale réunionnaise en est un des révélateurs. Ceci nous conduit à étudier la compétitivité-prix de La Réunion grâce au calcul et à l’examen des propriétés statistiques de l’indicateur de taux de change effectif réel. Il ressort que ce taux est stationnaire autour d’une tendance et qu’il ne révèle pas de phénomène de surévaluation significatif. Par conséquent les piètres performances en matière de commerce extérieur ne peuvent être mises sur le compte d’un euro qui serait « trop fort », mais doivent conduirent les décideurs à réfléchir sur les causes structurelles d’un modèle économique peu performant.taux de change réel, Stationnarité, racine unitaire, la reunion

Optimization of spray-dried hyaluronic acid microspheres to formulate drug-loaded bone substitute materials

Wepresent here our first results concerning the evaluation of hyaluronic acid (HA) as a candidate to formulate an organic–mineral cement with sustained release properties. Incorporating drug-loaded microspheres in mineral bone cements is an alternative strategy to improve their ability as drug delivery materials. To synthesize microspheres according to a reproducible process and control at the same time their morphology and their encapsulation efficiency is one of the main challenges of the conception of such drug-loaded bone substitute. In this context, we investigated the potentialities of two HA, differing by theirmolecular weight, to form microspheres by a spray-drying technique. Erythrosin B (EB) was encapsulated as a model drug and spray-drying process conditionswere optimized. To performthis, the rheological behavior and viscosity of HA solutions have been related to their spray-drying ability, and then to the resulting microparticles morphological properties and size distribution. Reproducible microspheres, answering to the requirements in terms of size and encapsulation efficiency, have been obtained from both HA. However the HA exhibiting the lowest molecular weight, HA600, led to smaller microparticles, with a higher polydispersity index. Their swelling ability, related to their stability upon rehydration, also appeared reduced. In this context, HA850, with the highest molecular weight, was selected and the possibility to modulate drug release by HA850 microspheres incorporation into a mineral cement was explored. EB release kinetics from HA microspheres, HA microspheres loaded cement and reference cement were followed at 37 °C, in Tris buffer at pH 7.4, using European Pharmacopoeia flow-through cells. Results showed that HA microspheres incorporation into a mineral cement permitted to modify the cement drug release profile and led to a sustained release

Adsorption on apatitic calcium phosphates for drug delivery: interaction with bisphosphonate molecules

Bisphosphonates (BPs) are well established as an important class of drugs for the treatment and prevention of several bone disorders including osteoporosis. This work investigated the interaction of two bisphosphonates, risedronate and tiludronate, with several apatitic supports, a well-crystallised hydroxyapatite (HA) and nanocrystalline apatites with varying maturation times, chemical composition and surface characteristics. The purpose was to fully understand the adsorption mechanism and desorption process, by the evaluation of the effect of several physicochemical parameters (temperature, pH and concentration of calcium and phosphate ions). Whatever the nature of the BP and the structure and composition of the apatite, the adsorption of such anti-resorptive agents can be well described as an ion exchange-reaction between phosphates species on the apatitic surface and BP molecules in solution. However, the parameters of adsorption can vary depending on the physicochemical conditions of the adsorption reaction. In addition, the structure and composition of the apatitic surface also influence the adsorption properties. Finally, BPs molecules are slowly released from apatitic supports, because most of the adsorbed molecules are irreversibly bound and not spontaneously released by dilution or simple washing. Moreover, similar to their adsorption, the release of bisphosphonates is strongly affected not only by the chemical properties of the molecule, but also by the chemical and structural characteristics of the apatitic substrates. The understanding of the adsorption and release processes provides fundamental tools for the development of drug delivery systems using apatite materials

Surface properties of biomimetic nanocrystalline apatites; applications in biomaterials

Several types of nanocrystalline apatites have been described, obtained in various ways. Among these, biomimetic nanocrystalline apatites (BNA), whose characteristics are close to those of biological apatites, have been shown to exhibit specific properties mainly related to their surface structure and composition. The aim of this paper is to review current knowledge of these compounds

Transcriptome analysis in non-model species: a new method for the analysis of heterologous hybridization on microarrays

Background: Recent developments in high-throughput methods of analyzing transcriptomic profiles are promising for many areas of biology, including ecophysiology. However, although commercial microarrays are available for most common laboratory models, transcriptome analysis in non-traditional model species still remains a challenge. Indeed, the signal resulting from heterologous hybridization is low and difficult to interpret because of the weak complementarity between probe and target sequences, especially when no microarray dedicated to a genetically close species is available. Results: We show here that transcriptome analysis in a species genetically distant from laboratory models is made possible by using MAXRS, a new method of analyzing heterologous hybridization on microarrays. This method takes advantage of the design of several commercial microarrays, with different probes targeting the same transcript. To illustrate and test this method, we analyzed the transcriptome of king penguin pectoralis muscle hybridized to Affymetrix chicken microarrays, two organisms separated by an evolutionary distance of approximately 100 million years. The differential gene expression observed between different physiological situations computed by MAXRS was confirmed by real-time PCR on 10 genes out of 11 tested. Conclusions: MAXRS appears to be an appropriate method for gene expression analysis under heterologous hybridization conditions