Between September 1981 and May 1986, coronary angioplasty immediately after intracoronary thrombolysis was attempted in 115 patients with acute myocardial infarction. The present study describes our experience with this combined procedure. Primary success was achieved in 102 patients (89%). Before discharge, 79 of these patients agreed to be restudied angiographically. The infarct-related vessel was still patent in 71 patients (patency rate of 90%). Sequential left ventricular angiograms of quality sufficient to allow automated analysis were obtained in 58 patients. Global ejection fraction improved significantly from 52 ± 10% to 55 ± 9% (p = 0.01) from the acute to the chronic stage. In patients with anterior infarction, the increase in global ejection fraction was primarily the result of significant improvement of the regional myocardial function of the infarct zone. No significant changes in global and regional myocardial function could be seen in patients with inferior infarction. However, when patients in whom the infarct-related vessel was reoccluded at follow-up angiography are excluded from analysis, the global and regional myocardial function did improve significantly irrespective of the location of the infarct. Median clinical follow-up of 20 months (range 4 to 50) resulted in an overall mortality rate of 4%. Preservation of global and regional left ventricular function with a low mortality rate suggests that immediate coronary angioplasty after thrombolysis can be safely used to provide reperfusion in the setting of acute myocardial infarction and that this combined procedure may be the optimal mode of therapy. Further randomized studies are warranted to precisely define the role of coronary angioplasty in acute myocardial infarction.
Abstract The application of design by finite element analysis (FEA) is becoming increasingly prevalent in applied engineering; however, codified provisions remain scarce. The vision of CEN/TC 250/SC 3 was to develop a new comprehensive document based on the existing provisions currently distributed throughout the different Eurocode 3 parts, and with extension where necessary to cover all fields of structural steel design. Within the development process, two documents are being prepared: (i) the code, prEN 1993‐1‐14 and (ii) a Technical Report. The new code aims to provide rules on the use of finite element analysis and other numerical methods for verifying ultimate limit states, serviceability limit states and fatigue. In parallel, the Technical Report will provide background information and explanations of all aspects of the code, as well as benchmark cases and design examples to support the correct application of the prEN1993‐1‐14 design rules and the necessary benchmarking required for model validation. The assumed stakeholders are mainly designers who can find direct guidance for design by finite element analysis in daily engineering practice. This current paper gives an overview of the new code and accompanying Technical Report, as well as the development process and harmonisation within the current Eurocode 3 framework.
Australian Calvinism is part of an international movement and it tends to reflect some of the strengths and weaknesses of its counterparts in Britain and the USA. The article traces the history of Calvinism and highlights its various features in Australia.
Radiographically guided investigations may be associated with excessive radiation exposure, which may cause skin injuries. The purpose of this study was to develop and test a system that measures in real time the dose applied to each 1-cm(2) area of skin, taking into account the movement of the x-ray source and changes in the beam characteristics. The goal of such a system is to help prevent high doses that might cause skin injury.The entrance point, beam size, and dose at the skin of the patient were calculated by use of the geometrical settings of gantry, investigation table, and x-ray beam and an ionization chamber. The data are displayed graphically. Three hundred twenty-two sequential cardiac investigations in adult patients were analyzed. The mean peak entrance dose per investigation was 0.475 Gy to a mean skin area of 8.2 cm(2). The cumulative KERMA-area product per investigation was 52.2 Gy/cm(2) (25.4 to 99.2 Gy/cm(2)), and the mean entrance beam size at the skin was 49.2 cm(2). Twenty-eight percent of the patients (90/322) received a maximum dose of <1 Gy to a small skin area ( approximately 6 cm(2)), and 13.5% of the patients (42/322) received a maximum dose of >2 Gy.Monitoring of the dose distribution at the skin will alert the operator to the development of high-dose areas; by use of other gantry settings with nonoverlapping entrance fields, different generator settings, and extra collimation, skin lesion can be avoided.
The effect of element interaction and material nonlinearity on the ultimate capacity of stainless steel plated cross-sections is investigated in this paper. The focus of the research lies in cross-sections failing by local buckling; member instabilities, distortional buckling and interactions thereof with local buckling are not considered. The cross-sections investigated include rectangular hollow sections (RHS), I sections and parallel flange channels (PFC). Based on previous finite element investigations of structural stainless steel stub columns, parametric studies were conducted and the ultimate capacity of the aforementioned cross-sections with a range of element slendernesses and aspect ratios has been obtained. Various design methods, including the effective width approach, the direct strength method (DSM), the continuous strength method (CSM) and a design method based on regression analysis, which accounts for element interaction, were assessed on the basis of the numerical results, and the relative merits and weaknesses of each design approach have been highlighted. Element interaction has been shown to be significant for slender cross-sections, whilst the behaviour of stocky cross-sections is more strongly influenced by the material strain-hardening characteristics. A modification to the continuous strength method has been proposed to allow for the effect of element interaction, which leads to more reliable ultimate capacity predictions. Comparisons with available test data have also been made to demonstrate the enhanced accuracy of the proposed method and its suitability for the treatment of local buckling in stainless steel cross-sections.