Background and ObjectivesThe so-called 'stress-induced cardiomyopathy' or takotsubo cardiomyopathy, mimicking acute myocardial infarction AMI , has recently been reported, particularly in Japan. We prospectively studied the clinical characteristics of, for the first time with a Korean series, this novel syndrome. Subjects and Methods Eighteen patients, fore filling the inclusion criteria, were entered onto the study. The criteria for inclusion were 1 no previous history of cardiac disease, 2 acute onset, 3 a regional wall motion abnormality in the left ventriculogram, typically in the apical segment, and 4 no significant stenosis in the coronary angiogram. Results The events preceding the condition included emotional stress N 7 , acute illness N 5 , non-cardiac surgery or medical procedure N 4 and accident N 2 . Chest pain, dyspnea, or nausea/vomiting were initially noted in 12 cases 66% . Pulmonary edema was demonstrated in 10 56% , and cardiogenic shock in 4 23% of the patients. The peak creatinine kinase MB fraction was 69 136 IU/L. A T wave inversion was noted in all patients, whereas, a Q wave was noted transiently in only 1. The average left ventricular ejection fraction LVEF was 38 8% on the initial echocardiograms. On the left ventriculograms, 15 patients showed akinetic wall motion, or aneurysmal dilatation in the apical wall, however, notably in 3 patients in the mid-ventricular wall. The coronary vasospasm provocation tests were negative in all 10 patients tested. An intravascular ultrasonography showed no infarct-related plaques in the 4 patients examined. On a follow-up echocardiogram, the average LVEF was improved to 51 8%, and regional wall motion was normalized after 30 29 days following onset. Conclusion We report, for the first time in a series of Korean patients, on a novel stress-induced cardiomyopathy with transient regional wall motion abnormality, mimicking AMI. The precise etiology remains to be elucidated in further studies.

The main contents of this paper are to verify the environmental factors affecting the power generation of floating photovoltaic systems and to present the power generation prediction model considering environmental factors by using regression analysis and neural networks studied during the last decade. This study focused on a comparative analysis of which model is best suited for the power generation prediction of the floating photovoltaic (PV) system. To compare the power generation characteristics of a floating and a land-based PV system, two identical 2.5 kW PV systems were installed—one on the water surface in the Boryeong Dam, Korea, and the other nearby on dry land—and their performances were compared. The solar irradiance of the floating PV system was 1.1% lower than that of the land-based PV. Nevertheless, the floating PV module temperature was 4.9% lower than that of the land-based PV, generating approximately 3% more power. Using the correlation analysis of data mining techniques, environmental factors affecting the efficiency of the floating PV system were investigated. The correlation coefficient between the module temperature and water temperature was r = 0.6317 which proves that the high efficiency and low module temperature characteristics of the floating PV system, when compared with that of the land-based PV, are due to the water evaporation effect. Considering environmental factors, power-generation prediction models based on regression analysis and neural networks are presented, and their accuracies are compared. This comparison confirms that the accuracy of the power generation prediction model using neural networks was approximately 2.59% higher than that of the regression analysis method. As a result of adjusting the hidden nodes in the neural network algorithm, it was confirmed that a neural network algorithm with ten hidden nodes was most suitable for calculating the amount of power generation.

Stress-induced cardiomyopathy is described as an acute cardiomyopathy that occurs under the influence of an excessive level of catecholamine related to intense emotional stress. A 64-year-old woman presented with symptoms of acute myocardial infarction after emotional upset, but her coronary angiographic findings were revealed to be normal. Diffuse T wave inversions were observed in her electrocardiograms with akinetic wall motions sparing the basal segments in her left ventriculography. After four months, her electrocardiogram and echocardiogram findings had completely returned to normal. The precise diagnosis of this acute cardiomyopathy must be emphasized because it can initially be misdiagnosed as acute coronary syndromes. However in complete contrast to acute myocardial infarction, it has a rapid and favorable recovery with hardly any sequelae after a few months.