Patchworking the Log-critical locus of planar curves

We establish a patchworking theorem \`a la Viro for the Log-critical locus of algebraic curves in $(\mathbb{C}^*)^2$. As an application, we prove the existence of projective curves of arbitrary degree with smooth connected Log-critical locus. To prove our patchworking theorem, we study the behaviour of Log-inflection points along families of curves defined by Viro polynomials. In particular, we prove a generalisation of a theorem of Mikhalkin and the second author on the tropical limit of Log-inflection points.Comment: 30 pages, 11 figures. Version 2: minor changes, new Remark 3.1, new Figure 6. Comments are welcom

Morphology based automatic acquisition of large-coverage lexica

International audienceIn this article, we introduce a new technique for constructing wide-coverage morphological lexica from large corpora and morphological knowledge, with an application to French. Basically, it relies on the idea that the existence of a hypothetical lemma can be guessed if several different words found in the corpus are best interpreted as morphological variants of this lemma. We first validated our technique by extracting verbs and adjectives on a general French corpus of 25 million words. Compared with other lexical resources available for French, our results are very satisfying, since we cover many words, often derived words, that are not always present in other lexica. Application of our algorithm to the acquisition of domain-specific adjectives on a botanic corpus gave also very good results, thus demonstrating its usability to extract domain-specific lexica. Moreover, it is generalizable to any language with a substantial morphology

The PGE2-Stat3 interaction in doxorubicin-induced myocardial apoptosis

Aims Both cyclooxygenase-2 (COX-2) and the transcription factor signal transducer and activator of transcription 3 (Stat3) are involved in adaptive growth and survival of cardiomyocytes. In ventricular cardiomyocytes, prostaglandin E2 (PGE2), a major COX-2 product, leads to adaptive growth via Stat3 activation, but whether this transcription factor acts as a signalling molecule in PGE2-induced cell survival is unknown. Therefore, the purpose of this study was to determine whether PGE2 counteracts cardiac apoptosis induced by doxorubicin (DOX), and if so, whether Stat3 plays a critical role in this cardioprotective effect. Methods and results Neonatal rat ventricular cardiomyocytes were incubated with DOX (0.5 µM) and/or PGE2 (1 µM). Apoptosis was assessed by determining caspase3 activation and apoptotic DNA fragmentation. The role of Stat3 was evaluated in vitro and in vivo by transfecting cardiomyocytes with siRNA targeting rat Stat3 and by using cardiomyocyte-restricted Stat3 knockout (Stat3 KO) mice, respectively. Incubation of ventricular cardiomyocytes with PGE2 led to a time-dependent decrease in the DOX-induced caspase3 activation, reaching a maximal inhibition of 70 ± 5% after 4 h. Similarly, PGE2 inhibited DOX-induced DNA fragmentation by 58 ± 5% after 24 h. This antiapoptotic action of PGE2 was strongly reduced by the ERK1/2 inhibitor, U0126, whereas the p38 MAP kinase inhibitor, SB203580, had no effect. Depleting Stat3 expression by 50-60% in isolated ventricular cardiomyocytes markedly reduced the protective effect of PGE2 on DOX-induced caspase3 activation and DNA fragmentation. Likewise, the stable PGE2 analogue, 16,16-dimethyl-PGE2, was unable to counteract cardiac apoptosis induced by DOX in Stat3 KO mice. Conclusion Our results demonstrate that PGE2 prevents myocardial apoptosis induced by DOX. This protection requires the activation of the prosurvival pathways of Stat3 and ERK1/

The Connection between Biaxial Orientation and Shear Thinning for Quasi-Ideal Rods

The complete orientational ordering tensor of quasi-ideal colloidal rods is obtainedas a function of shear rate by performing rheo-SANS (rheology with small angle neutronscattering) measurements on isotropic fd-virus suspensions in the two relevant scatteringplanes, the flow-gradient (1-2) and the flow-vorticity (1-3) plane. Microscopic ordering canbe identified as the origin of the observed shear thinning. A qualitative description of therheological response by Smoluchowski, as well as Doi–Edwards–Kuzuu theory is possible,as we obtain a master curve for different concentrations, scaling the shear rate with theapparent collective rotational diffusion coefficient. However, the observation suggests that theinterdependence of ordering and shear thinning at small shear rates is stronger than predicted.The extracted zero-shear viscosity matches the concentration dependence of the self-diffusion ofrods in semi-dilute solutions, while the director tilts close towards the flow direction already atvery low shear rates. In contrast, we observe a smaller dependence on the shear rate in the overallordering at high shear rates, as well as an ever-increasing biaxiality