Magnetically textured y-Fe2O3 nanoparticles in a silica gel matrix: structural and magnetic properties

International audienceThis paper is devoted to magnetic and structural properties of anisotropic g -Fe2O3 superparamagnetic particles dispersed in a transparent xerogel matrix. The effect of frozen anisotropy axes and magnetic texture, induced by a magnetic field applied during the solidification of the matrix on the in-field magnetization process, is studied by alternating gradient force magnetometry and first and second order magneto-optical effects. The changes of magnetization curves with respect to the ferrofluid solution at the same particle concentration are interpreted on the basis of an existing statistical approach extended to systems with particle size distribution, which has to be taken into account for real samples. A very good agreement between the experiment and theory was achieved for a log-normal distribution of diameters which well resembles that deduced from electron microscopy observations in different imaging modes. This structural analysis states the parameter values used in calculations and confirms the relevance of basic assumptions of the model for the specimens studied. The experimental results and the related theoretical discussion should be of use to understand magnetic properties of other magnetically textured superparamagnetic system

An analysis and an affordable regularization technique for the spurious force oscillations in the context of direct-forcing immersed boundary methods

The framework of this paper is the improvement of direct-forcing immersed boundary methods in presence of moving obstacles. In particular, motivations for the use of the Direct Forcing (DF) method can be found in the advantage of a fixed computational mesh for fluid–structure interaction problems. Unfortunately, the direct forcing approach suffers a serious drawback in case of moving obstacles: the well known spurious force oscillations (SFOs). In this paper, we strengthen previous analyses of the origin of the SFO through a rigorous numerical evaluation based on Taylor expansions. We propose a remedy through an easy-to-implement regularization process (regularized DF). Formally, this regularization is related to the blending of the Navier–Stokes solver with the interpolation, but no modification of the numerical scheme is needed. This approach significantly cuts off the SFOs without increasing the computational cost. The accuracy and the space convergence order of the standard DF method are conserved. This is illustrated on numerical and physical validation test cases ranging from the Taylor–Couette problem to a cylinder with an imposed sinusoidal motion subjected to a cross-flow

Single day 2 embryo versus blastocyst-stage transfer: a prospective study integrating fresh and frozen embryo transfers

International audienceWhether extended culture allowing selection of embryos with high development potential has any advantage over cleavage-stage embryo transfer remains a matter of debate. Among the currently unsolved questions, the cumulative delivery rate resulting from fresh and frozen embryo transfers needs to be taken into account in both strategies. The aim of our study was, therefore, to compare the efficacy of single embryo transfer either on Day 2 or on Day 5/6 combining fresh and frozen embryo transfers. A prospective study including 478 couples assigned on a voluntary basis to undergo elective single embryo transfer (eSET, n = 243) on Day 2 or single blastocyst transfer (SBT, n = 235) on Day 5/6 was performed. The primary outcome measurement was the cumulative delivery rate including fresh and frozen-thawed cycles in both groups. The delivery rate per cycle following fresh embryo transfer was significantly higher in the SBT group compared with the eSET group (P < 0.01). Conversely, frozen embryo and/or blastocyst transfers tended to result in a higher number of deliveries in the eSET compared with the SBT group. Altogether, the cumulative delivery rate per couple, including fresh and frozen embryo transfers, was similar between the two groups (37.9% versus 34.2% in the SBT and eSET groups, respectively). The observed cumulative delivery rates in this study do not allow us to take a position in favor of SBT or eSET. An improvement in blastocyst cryopreservation may change this attitude

Weak D caused by a founder deletion in the RHD gene.

International audienceBACKGROUND: The RhD blood group system exemplifies a genotype-phenotype correlation by virtue of its highly polymorphic and immunogenic nature. Weak D phenotypes are generally thought to result from missense mutations leading to quantitative change of the D antigen in the red blood cell membrane or intracellularly. STUDY DESIGN AND METHODS: Different sets of polymerase chain reaction primers were designed to map and clone a deletion involving RHD Exon 10, which was found in approximately 3% of approximately 2000 RHD hemizygous subjects with D phenotype ambiguity. D antigen density was measured by flow cytometry. Transcript analysis was carried out by 3'-rapid amplification of complementary DNA ends. Haplotype analysis was performed by microsatellite genotyping. RESULTS: A 5405-bp deletion that removed nearly two-thirds of Intron 9 and almost all of Exon 10 of the RHD gene was characterized. It is predicted to result in the replacement of the last eight amino acids of the wild-type RhD protein by another four amino acids. The mean RhD antigen density from two deletion carriers was determined to be only 30. A consensus haplotype could be deduced from the deletion carriers based on the microsatellite genotyping data. CONCLUSION: The currently reported deletion was derived from a common founder. This deletion appears to represent not only the first large deletion associated with weak D but also the weakest of weak D alleles so far reported. This highly unusual genotype-phenotype relationship may be attributable to the additive effect of three distinct mechanisms that affect mRNA formation, mRNA stability, and RhD/ankyrin-R interaction, respectively

Le français : des mots de chacun, une langue pour tous

Vraie problématique linguistique, socio-économique et culturelle que traitent dans ce volume des chercheurs et des universitaires, des enseignants et des hommes d’affaires, des juristes et des écrivains. Comment faire pour que les mots spécialisés de nos professions, ancrés dans des savoir-faire, deviennent également les formes ouvertes d’une langue à partager ? Comment faire aussi pour que les mots de tous les jours, ceux des enfants des banlieues comme ceux des fils de la terre, soient les gages d’une compréhension et d’une reconnaissance mutuelles, d’un accès à la langue des pères, dans une société en perpétuel mouvement ? Comment faire encore pour mettre en résonance les accents des français régionaux et les échos lointains des français de la francophonie, afin que se déploie plus largement cet idéal linguistique commun ? Autant de questions qui trouvent leur champ de réflexion et leur voie de réponse dans les différentes parties de cet ouvrage : le lecteur chemine d’abord à travers les accents du français parlé, en France et dans la francophonie, pénètre au cœur des particularités de l’écrit, réfléchit aux conditions des échanges et du partage de la langue pour pénétrer enfin dans le monde des poètes et s’initier aux enchantements de la langue littéraire qui n’a cessé de dire la vie, la jouissance et la fortune des mots d’où qu’ils proviennent, ceux de La Pléiade, archaïques, techniques ou dialectaux, ceux des poètes modernes, riches de sensations, constellés d’associations, pleins de fulgurances, ceux de Léopold Sedar Senghor, vibrant aux accords de l’Afrique et de la France, fondues dans une mythologie neuve, faite de valeurs singulières mais partagées, métissées par deux cultures dans une même vision poétique. Finalement, c’est encore là une belle escale dans le temps et l’espace que cette troisième étape du voyage au long cours que constituent les Lyriades renouvelées de la langue française. Cet ouvrage est issu des 3e journées de la langue française, Les Lyriades, qui se sont tenues à Liré en Anjou, les 19-20-21 mai 2006. Il a été conçu sous la direction de Françoise Argod-Dutard, professeur des universités et responsable du comité scientifique avec la collaboration de Dominique Beaumon, coordonnateur des Lyriades