Biomedical subjects

PA Kelly

Publications and source records attributed to PA Kelly.

2 recordsLinked to original sources

PubMed2000

The quasistatic approximation for a cracked interface between a layer and a substrate

Heuristic in nature, the quasistatic approximation (QSA) describes the interaction of ultrasonic waves with imperfect interfaces by modeling the interfacial imperfection as distributions of springs and masses. The QSA does not provide any relationship between the interfacial stiffness constants and the micromechanics of the defects. The aims of this paper are threefold. First, a derivation from first principles of the QSA boundary conditions on a cracked interface is presented. Relationships linking the interfacial constants to the mechanical and geometrical properties of the distributed cracks are also obtained. Second, the stiffness dependence of a cracked interface between a layer and a substrate on the layer thickness is investigated. It is shown that the interfacial stiffnesses cannot be regarded as intrinsic properties of the interface, but they may also depend on the structural properties of the hosting system. Finally, the effect of the thickness dependence of the interfacial stiffnesses on the phase velocity of the lowest mode supported by the layered structure is investigated.

Journal Article↗

PubMed1997

Total Endovascular Reconstruction of Occluded Saphenous Vein Grafts Using Coronary or Peripheral Wallstents.

Degeneration of saphenous vein grafts (SVG) resulting in severe stenosis and, ultimately, occlusion is common. Re-do bypass grafting is less successful than the original operation. Intervention with balloon angioplasty alone has poor long-term results, and although improved long-term benefit has been demonstrated with stenting, most stents are limited by their diameter and length. The self-expanding Wallstent has a number of properties that make it particularly suitable for this purpose. We reviewed 26 patients, mean age 64.9 years, 24 males, who had Wallstents deployed in totally occluded or severely obstructed SVG. Seven patients had total graft occlusion, all patients had severe diffuse graft body disease. The mean length of Wallstent used was 54.1 mm. Routine anti-coagulation protocol was used. There were 2 major initial adverse events and no further in-hospital complications. Mean follow-up was 18.8 months. A total of 3 major late clinical events were identified. We conclude that coronary or peripheral Wallstents should be considered for the management of these patients.

Journal Article↗