Aix-Marseille University

About: Aix-Marseille University is a education organization based out in Marseille, France. It is known for research contribution in the topics: Population & Galaxy. The organization has 24326 authors who have published 54240 publications receiving 1455416 citations. The organization is also known as: University Aix-Marseille & université d'Aix-Marseille.

Modern unicompartmental knee arthroplasty with cement: a three to ten-year follow-up study.

Abstract: Background Unicompartmental arthroplasty is a treatment alternative when only one compartment of the knee is affected with arthritis, but the reported results of this procedure have been variable The purpose of the present study was to evaluate the results of a modern unicompartmental knee arthroplasty performed with use of a cemented metal-backed prosthesis and surgical instrumentation comparable with that used for total knee replacement Methods The indications for the procedure were osteonecrosis or osteoarthritis associated with full-thickness loss of cartilage that was limited to one tibiofemoral compartment as evaluated on standing and stress radiographs One hundred and sixty consecutive cemented metal-backed Miller-Galante prostheses in 147 patients were evaluated after a mean duration of follow-up of sixty-six months (range, thirty-six to 112 months) The mean age of the patients at the time of the index procedure was sixty-six years Results Three knees were revised because of progression of osteoarthritis in the patellofemoral joint (two knees) or the lateral tibiofemoral compartment (one knee) Two knees had revision of the polyethylene liner The average Hospital for Special Surgery knee score improved from 59 points preoperatively to 96 points at the time of the review According to Kaplan-Meier analysis, the ten-year survival rate (with twenty-nine knees at risk) was 94% +/- 3% with revision for any reason or radiographic loosening as the end point Conclusions A modern unicompartmental knee arthroplasty is a valid alternative for patients with unicompartmental tibiofemoral noninflammatory disease The patient selection must be strict with regard to the status of the patellofemoral joint The preoperative planning includes stress radiographs to assess the correction of the deformity and the status of the uninvolved compartment Continued long-term follow-up is necessary to evaluate long-term polyethylene wear

Rheology of dense granular suspensions

Abstract: Suspensions are composed of mixtures of particles and fluid and are omnipresent in natural phenomena and in industrial processes. The present paper addresses the rheology of concentrated suspensions of non-colloidal particles. While hydrodynamic interactions or lubrication forces between the particles are important in the dilute regime, they become of lesser significance when the concentration is increased, and direct particle contacts become dominant in the rheological response of concentrated suspensions, particularly those close to the maximum volume fraction where the suspension ceases to flow. The rheology of these dense suspensions can be approached via a diversity of approaches that the paper introduces successively. The mixture of particles and fluid can be seen as a fluid with effective rheological properties but also as a two-phase system wherein the fluid and particles can experience relative motion. Rheometry can be undertaken at an imposed volume fraction but also at imposed values of particle normal stress, which is particularly suited to yield examination of the rheology close to the jamming transition. The response of suspensions to unsteady or transient flows provides access to different features of the suspension rheology. Finally, beyond the problem of suspension of rigid, non-colloidal spheres in a Newtonian fluid, there are a great variety of complex mixtures of particles and fluid that remain relatively unexplored.

Interplay of cell dynamics and epithelial tension during morphogenesis of the Drosophila pupal wing.

Abstract: The individual cells in a developing animal embryo organize themselves into tissues with specific and reproducible shapes, which requires the cells to communicate with one another. Cells in tissues exert forces on their neighbors, and respond to being pushed and pulled by the cells around them. In the fruit fly Drosophila melanogaster, each wing consists mainly of a framework of proteins and other molecules that is built by epithelial cells. These epithelial cells divide and grow during the life of a fly larva, and then reorganize themselves into the shape of the wing after it forms into a pupa. During this reshaping, epithelial cells in some regions of the wing experience powerful contractions. Previous work had suggested that and these forces produced tension in the rest of the wing to pull it into its final elongated shape. But it wasn't clear what exactly these contractions were pulling against to produce the tension. Nor was it understood exactly how wing epithelial cells responded to tension to reorganize themselves into a different wing shape. Now, Etournay, Popovic, Merkel, Nandi et al. have analyzed the forces acting across the entire wing blade and how these forces shape the wing. All cell divisions, cell neighbor exchanges and changes in cell shape in the developing wing blade were tracked under a microscope; this revealed how each one of them contributed to the change in wing shape. Further experiments revealed that localized contractile forces produce tension in the wing because it is connected around its edge to surrounding structures via an extracellular protein called Dumpy. Releasing these contacts, by severing them with a laser or by mutating Dumpy, caused the wing to develop into abnormal shapes, showing that the tension in the wing blade has an important role in determining wing shape. Furthermore, by tracking cells in wings that had been severed by a laser, or mutated for Dumpy Etournay, Popovic, Merkel, Nandi et al. could figure out exactly which cellular processes were guided by epithelial tension. Etournay Popovic, Merkel, Nandi et al. also present a theoretical model that describes how the interplay between active force generation and the response of cells to the resulting tension shapes the wings of fruit flies. They propose that epithelial tension provides a mechanism through which cells can communicate with each other to ensure that together the combined behavior of these cells generates reproducible shapes. Further studies are required to analyze how active force generation is patterned and cells sense and respond to external forces during development.

De novo metagenomic assembly reveals abundant novel major lineage of Archaea in hypersaline microbial communities.

Abstract: De novo metagenomic assembly reveals abundant novel major lineage of Archaea in hypersaline microbial communities