Christian Dior (France)

Why different bird species lay different numbers of eggs is a question that has long been associated with factors external to the organism, that is, factors which operate on inherited variation in clutch size through the action of natural selection. Yet, while external factors are important, the extent of what is evolutionarily possible rests with the mechanisms developed by birds for clutch-size control. Hitherto neglected, these mechanisms generate factors internal to the organism that are central to the origin of evolutionary change. They are related to the fact that a species-specific range of clutch size arises from the differential survival of pre-ovulatory follicles undergoing growth when the signal causing egg laying to end reaches the ovary. Herein, I examine three internal factors that, together with external factors, could impact the evolution of avian clutch size. Each factor acts by changing either the number of pre-ovulatory follicles present in the ovary at the time of follicular disruption or the timing of this event. These changes to clutch size can be explained by the concept of heterochrony. In light of this, the role of phenotypic plasticity and genes determining clutch size is discussed. Finally, to account for the origin of evolutionary change in clutch size, I detail an hypothesis involving a process similar to Waddington's theory of genetic assimilation.

The purpose of this study was to evaluate the effects of a GENESIS-BCP™ scaffold composed of hydroxyapatite (HAp) and β-tricalcium phosphate (β-TCP) on bone formation. The relative ratio of components forming GENESIS-BCPTM was investigated by confirming the molar ratio of Ca/P through energy dispersive spectrometer (EDS) analysis. The results being that the scaffold is comprised of 60% HAp and 40% β-TCP. Moreover, scanning electron microscopy (SEM) images showed a unique surface morphology similar to a soccer ball. X-ray diffraction (XRD) analysis showed that the porosity, crystallinity, and Ca/P ratio were 65.5%, 84.9%, and 1.61%, respectively. In vitro tests including cytotoxicity and cell proliferation showed a good biocompatibility of GENESIS-BCP™. In vivo tests, including mouse skull test, and hematoxylin and eosin stains of GENESIS-BCP™ implanted in rabbit and human subjects showed that the bone graft is effective to accelerate new bone formation. It was concluded that GENESIS-BCP™ can be used as an effective alloplast bone graft.

La revista ICONO 14 publica trabajos científicos cuya temática aborde la comunicación bajo la perspectiva de las Tecnologías de la Información y Comunicación, y muy especialmente de las tecnologías emergentes, aplicadas a diversos campos del conocimiento, mediante investigación básica o aplicada, experimental, descriptiva o epistemológica

Total knee replacement (TKR) for treatment of osteoarthritis in a valgus knee is, in most cases, not more challenging than in a varus knee. However, in the presence of severe valgus deformity, it is more difficult to achieve good ligament balance and adequate bone coverage, despite contracture of the lateral structures. The worst case scenario is a mixed deformity which combines wear, contracture of lateral structures, slackening of medial ligamentous structures, and extra-articular bone deformity as may be seen after tibial osteotomy or post-traumatic malunion.

En 1780, le critique littéraire Edward Capell publiait une courte note, dans Notes and Various Readings to Shakespeare, dans laquelle il indiquait que Shakespeare s’était inspiré des propos de Montaigne dans l’essai « Des Cannibales » (i, 31) pour composer le discours de Gonzalo, sur un état idéal, dans La Tempête (ii.ii.143-52) : « The speech that offers these changes, and one after it, prove the writer’s acquaintance with one he has not been trac’d in by any, annotator or editor ; for then ...

Une forme de proximité entre Shakespeare et Montaigne a déjà été repérée, en particulier par l’autre géant, Hugo. On voudrait s’intéresser ici à la présence, chez l’un et chez l’autre, de Plutarque. Mais de quel Plutarque, au juste ? Chez Montaigne, Plutarque est surtout le modèle d’un psycho-historien, mais pas seulement cela… Chez Shakespeare, Plutarque est surtout un metteur en scène, un dramaturge virtuel, mais pas seulement cela… Chez l’un et l’autre, l’accent est mis décisivement sur les obscurités du sujet, son trouble, son inconsistance, son altérité. N’est-ce pas là l’héritage de Plutarque, du Plutarque auteur de l’E de Delphes ? Si l’héritage est légué en voie directe à Montaigne, peut-être est-il transmis à Shakespeare par l’intermédiaire des Essais ?

Countercurrent chromatography is a powerful separation technique based on the partition of solutes between two immiscible liquid phases. The first one, maintained in the column by a centrifugal force, acts as the stationary phase; the second phase, circulating through the apparatus, elutes compounds according to their partition coefficients. The total liquid nature of this process allows the addition of auxiliary components in both phases, increasing the separation power of countercurrent chromatography. In 1991, Y. Ito introduced pH-Zone refining systems in which the stationary phase contains a retainer and the mobile one an eluter. The acid-base system that acts as the retainer-eluter pair interacts with solutes and enables a separation based on acidic constant (pKa) base. First, this method was successfully used to separate and purify two poly-aza heterocyclic isomers, obtained by hetarynic dimerization and which are precursors of antitumor agents. Because of several imperatives, a new system, adapted from the classical one (eluter-retainer), was developed to respect our limitations. Secondly, ionic solutes such as sulfonic acid compounds cannot be studied by such a system, based on the influence of the acidic constant. Therefore, the retainer is replaced by a cationic liquid resin with very strong hydrophobic properties. Added to the organic stationary phase, this resin gives the stationary phase an ion-exchange behavior, guided by the eluter contained in the mobile phase. Applied to ionic solutes, the study of this new system highlights the main parameters of the separation.

A series of highly concentrated lipophilic cosmetic emulsions were analysed, in order to determine their rheological and textural properties, as a function of their microstructure. The originality of this study lies in the methodology used, especially the shear-stress scanning analysis. The results of a very powerful and comprehensive dynamic rheological analysis suggest the existence of two critical volume fraction values: besides the “close-packed” value φ c , a “slack-packed” value φ0, close to 0.60 could be demonstrated. It has been shown that the close-packed structure is stable under shear; in constrast, the slack-packed configuration, defined as φ0<φ<φ c is unstable under shear. A comparison with theoretical models, especially that of Princen, showed good agreement and allowed the close-packed value φ c to be defined more precisely as 0.67. The gap between 0.67 and 0.74 is probably indicative of a highly polydisperse distribution, as confirmed by microscopic analysis. Flow experiments confirmed the validity of Princen‘s model.