The materials used up to now for grafting arteries have not proved entirely satisfactory. It was the purpose of the project described here to find a more satisfactory method for replacing arteries. Previous experience has shown that glutaraldehyde-treated grafts are non-viable, avascular, and known to pre serve their general structure. In this study small bowel taken from a cat and treated with glutaraldehyde was used to replace the aorta in dogs. Ten dogs were used. The G.A. treated graft in a length of 10 cm bypassed the abdominal aorta. The dogs were sacrificed from 20 days up to one year. Repeated angiographies showed the patency of the graft. After sacrificing the dogs, the grafts were examined macroscopically and microscopically. The site of the anastomosis was strong and no aneurysms were seen. The graft is easy to handle and can be tailored to size.
Defecting the existence of a fault in complex systems is neither sufficient nor economical without diagnostics assisting in fault isolation and cost-effective repairs. This work attempts to put in economical terms the technical decisions involving diagnostics. It looks at the cost factors of poor diagnostics in terms of the accuracy and completeness of fault idestification and the time and effort it takes to come to a final (accurate) repair decision. No Problems Found (NPF), Retest OK (RTOK), False Alarms, Cannot Duplicates (CND) and other diagnostic deficiencies can range from 30% to 60% of a// repair actions. According to a 1995 survey run by the /€€E Reliability Society, the Air Transport Association (ATA) has determined that 4500 NPF events cost ATE member airlines $100 million annually. A US. Army study has shown that maintenance costs can be reduced by 25% if 7040% of the items it had been repairing were to be discarded. Many of these situations can be overcome by investing in emerging technologies, such as Built-ln (Selr) Test (BIST) and expert diagnostic tools. The role of these tools is to minimize dependence on the skills, knowledge and experience of individuals, and thus overcome costs of inaccurate, inefficient, and incomplete diagnostics. Use of BlST can also directly reduce costs. This paper will present technical solutions and economic analyses showing to what extent such solutions provide a sufficient return on investment.
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