Summary. Generalized A(c~)-stable Runge-Kutta methods of order four with stepsize control are studied. The equations of condition for this class of semiimplicit methods are solved taking the truncation error into consideration. For application an A-stable and an A(89.3~ method with small truncation error are proposed and test results for 25 stiff initial value problems for different tolerances are discussed.

SUMMARY Streptokinase was infused into the ischemia-related coronary artery at a rate of 1000-2000 U/min for 15-95 minutes in 29 patients with acute myocardial infarction(AMI group) and in five patients with unstable angina pectoris (UAP group). Reopening of the completely obstructed vessel or increase of diameter at the site of subtotal lesions occurred in 22 AMI patients within 15-90 minutes of streptokinase infusion. In four of these patients, antegrade flow to the distal segments of the infarct vessel was seen after intracoronary nitroglycerin or sublingual nifedipine administration, which preceded streptoklinase infusion, and in two patients, streptokinase infusion was combined with recanalization by means of a guide wire. Chest pain was alleviated after reperfusion; ejection fraction was 50.5 ± 12% before and 54.6 ± 9% immediately after successful intracoronary lysis (p < 0.05). Repeat angiography, performed 25 ± 11 days after the acute intervention in 19 AMI patients, revealed reocclusion of the infarct vessel in one patient. Aortocoronary bypass surgery was performed electively in six AMI patients at varying intervals after successful lysis. Upon intraoperative inspection, the bulk of myocardium perfused by the recanalized vessel was found to be viable.Intracoronary streptokinase infusion did not result in opening the complete obstruction or improvement of lumen at the site of subtotal lesions in seven AMI patients and in all UAP patients. The total dose of 128,000 ± 36,000 U of streptokinase resulted in only minor decrease of fibrinogen, from 451 ± 93 mg% to 430 ± 91 mg%. Bleeding from the arterial puncture site in two patients, the only complications that could be attributed to the procedure, was due to heparinization.Intracoronary streptokinase application appears to be a safe and efficient method of achieving reperfusion and alleviating ischemia in the majority of patients with acute myocardial infarction. The method was not beneficial in treating unstable angina pectoris, and its potential for salvage of myocardium is yet to be assessed.IN A PREVIOUS STUDY, coronary angiography performed in 18 medically treated infarct patients during the acute and chronic stage revealed spontaneous recanalization of the infarct vessel in 40% of the cases.' In another study, acutely occluded coronary arteries could be recanalized mechanically by use of guide wires and catheters in 10 patients.2 Repeat angiography in the chronic stage of myocardial infarction showed increases in diameter of the recanalization canal in six of these patients. Most 307Materials and Methods Study GroupThe study group consisted of 34 patients in whom acute coronary angiography was performed between June 22, 1979 and March 30, 1980. The final diagnosis of AMI (patients 1-29) and UAP (patients 30-34) was based on serial CPK4 and CK-MB5 values. These enzymes were normal in the UAP patients, but were increased to pathologic levels (peak CPK 879 ± 816 U/1) in the AMI patients. All patients were admitted to the hospital because they had ches...

In technical applications, uncertainties are a topic of increasing interest. During the last years the Polynomial Chaos of Wiener (Amer. J. Math. 60(4),897-936, 1938) was revealed to be a cheap alternative to Monte Carlo simulations. In this paper we apply Polynomial Chaos to stationary and transient problems, both from academics and from industry. For each of the applications, chances and limits of Polynomial Chaos are discussed. The presented problems show the need for new theoretical results.

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Summary.A modification of the well-known continuation (or homotopy) method for actual computation is worked out. Compared with the classical method, the modification seems to be a more reliable device for supplying useful initial data for shooting techniques. It is shown that computing time may be significantly reduced in the numerical solution of sensitive realistic two-point boundary value problems.