Characterization of Initial Parameter Information for Lifetime Prediction of Electronic Devices.

Newly manufactured electronic devices are subject to different levels of potential defects existing among the initial parameter information of the devices. In this study, a characterization of electromagnetic relays that were operated at their optimal performance with appropriate and steady parameter values was performed to estimate the levels of their potential defects and to develop a lifetime prediction model. First, the initial parameter information value and stability were quantified to measure the performance of the electronics. In particular, the values of the initial parameter information were estimated using the probability-weighted average method, whereas the stability of the parameter information was determined by using the difference between the extrema and end points of the fitting curves for the initial parameter information. Second, a lifetime prediction model for small-sized samples was proposed on the basis of both measures. Finally, a model for the relationship of the initial contact resistance and stability over the lifetime of the sampled electromagnetic relays was proposed and verified. A comparison of the actual and predicted lifetimes of the relays revealed a 15.4% relative error, indicating that the lifetime of electronic devices can be predicted based on their initial parameter information.

The role of prourokinase gene in protecting vein grafts from intimal hyperplasia.

OBJECTIVE: To study the duration of prourokinase gene expression in vein grafts and the role of the prourokinase gene in protecting vein grafts from neointimal hyperplasia. METHODS: Fifty-four Wistar rats were used in this study. In each rat, the jugular vein was excised and distended for 30 minutes using a solution containing either Adv(5)-CMV (control group) or Adv(5)-CMV/Pro-UK (treatment group). Next, the jugular vein was reversed and interposed into the divided carotid artery of the same rat. On the 14th day after transfection, vein grafts of the control group were collected in order to perform a fibrinolysis test for prourokinase (Pro-UK) activity. On the 2nd, 7th, 14th, 28th, and 60th day, the vein grafts of the treatment group were likewise collected in order to detect prourokinase activity. On the 28th day, the vein grafts of both groups were explanted to evaluate the (3)H-TDR incorporation so that pathologic analysis could be performed. RESULTS: Pro-UK activity could not be detected in the control group, while in the treatment group, the Pro-UK activity could be detected from the 2nd day onwards, peaking on the 7th day and declining from the 14th day, but yet persisting at a low level for a further month. The amount of (3)H-TDR incorporated in the control group was higher than that in the treatment group. Pathologic analysis demonstrated that vein grafts of both groups exhibited wall thickening, but that the degree of graft neointimal hyperplasia and reduction of the graft lumen was greater in the control group than that in the treatment group. The occlusion rate of grafts in the control group was 20%. All grafts in the treatment group were patent. CONCLUSIONS: Pro-UK gene transfer before vein grafting in vitro results in a high level of gene expression in the vein graft from the 7th day to 14th day. And its gene expression in the vein graft could reduce neointimal hyperplasia in the vein graft.