Simple geometry tribological study of osteochondral graft implantation in the knee

Robust preclinical test methods involving tribological simulations are required to investigate and understand the tribological function of osteochondral repair interventions in natural knee tissues. The aim of this study was to investigate the effects of osteochondral allograft implantation on the local tribology (friction, surface damage, wear and deformation) of the tissues in the natural knee joint using a simple geometry, reciprocating pin-on-plate friction simulator. In addition, the study aimed to assess the ability of osteochondral grafts to restore a low surface damage, deformation and wear articulation when compared to the native state. A method was developed to characterise and quantify surface damage wear and deformation of the opposing cartilage-bone pin surface using a non-contacting optical profiler (Alicona Infinite Focus). Porcine 12 mm diameter cartilage-bone pins were reciprocated against bovine cartilage-bone plates with 6 mm diameter osteochondral allografts, cartilage defects or stainless steel pins (positive controls) inserted centrally. Increased levels of surface damage with changes in geometry were not associated with significant increases in the coefficient of dynamic friction. Significant damage to the opposing cartilage surface was observed in the positive control groups. Cartilage damage, deformation and wear (as measured by change in geometry) in the xenograft (2.4 mm³) and cartilage defect (0.99 mm³) groups was low and not significantly different (p>0.05) compared to the negative control in either group. The study demonstrated the potential of osteochondral grafts to restore the congruent articular surface and biphasic tribology of the natural joint. An optical method has been developed to characterise cartilage wear, damage and deformation, that can be applied to the tribological assessment of osteochondral grafts in a whole natural knee joint simulation model

Mechanical Properties and Tribology of Tissue Engineered Cartilage

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Carcinomes canalaires in situ du sein : valeur diagnostique de la microbiopsie et place dans la statégie chirurgicale (à propos du suivi chirurgical et anatomopathologique de 197carcinomes canalaires in situ diagnostiqués par biopsie percutanée au Centre Léon Bérard [de Lyon] entre juin 1994 et décembre 2001)

LYON1-BU Santé (693882101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Un algorithme conservatif de dètection des miettes en milieu rèparti

International audienceNous présentons un nouveau protocole pour la détection de miettes réparties. Il se prête à une mise en oeuvre au niveau système. Il se base sur des hypothèses réalistes : un message peut se perdre ou être dupliqué; un site peut tomber en panne; un objet peut migrer ou être effacé. Ce protocole n'utilise que des informations locales à un site, ou échangées entre deux sites; aucun mécanisme global n'est nécessaire. Il est parallèle et se prête à des systèmes à très grande échelle. Il tire parti des autres composantes du système, comme le protocole de recherche des objets. Son interface permet une grande indépendance entre les composants

A Distributed Garbage Collection in an Object-Support Operating System

International audienceWe describe a distributed garbage collector protocoltargeted for uncooperative distributed object orientedsystems. The protocol has been implementedon distributed Lisp system and a few performancemeasurements are discussed. Since this implementation,we have refined deeply the protocol to addressnon FIFO channels. A new reference model is proposedalong with the protocol to improve invocationefficiency.1 IntroductionOur research is concerned with distributed garbagecollectio

Distributed Garbage Collection in the System is Good

International audienceWe present a protocol for the distributed detection of garbage in a distributed system subject to common failures such as lost and duplicated messages, network partition, dismounted disks, and process, site and disk crashes. The protocol uses only information local to each site, or exchanged between pairs of sites; no global mechanism is necessary. Since overhead is low, the protocol can be integrated into the operating system. We show than a logical separation of responsibility allows to integrate in the operating system the detection rôle leaving up to the application the collection rôl