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The Fukushima Daiichi nuclear disaster occurred during the Great East Japan Earthquake. Inside the reactor, materials with high radioactivity were scattered entirely, leading to a severe condition that restricted the number of measurement spots where the detector could be used. We propose a new system based on a plane model that uses fewer measurement spots and causes fewer estimation errors. We estimated the radiation source distribution using the maximum-likelihood estimation method optimized by gradient descent. Consequently, it was found that the proposed system, showed fewer errors than the previous system with a limited number of measurement spots. [ABSTRACT FROM AUTHOR]

Background: Heart failure (HF), which can be caused by left ventricular systolic dysfunction (LVSD), is a growing problem in developed countries with a large aging population. The aim of the present study was to characterize outpatients with LVSD in the adult population (45-84 years) in an urban Japanese community (Niigata City), and delineate their characteristics in comparison with those in a rural one (Sado)., Methods and Results: Over a 5-year period, 1,297 patients (67% males) with LVSD (defined as ejection fraction < or =50%) were extracted from 87,953 echocardiography records available in 15 hospitals in Niigata City. The proportion of LVSD increased progressively with age (p-for-trend <0.0001), reaching 1-2% in those aged > or =75 years. The prevalence of comorbidities was noticeable (47% had hypertension, 41% myocardial ischemia, 34% atrial fibrillation, 33% previous hospitalization because of congestive HF, 27% cerebral stroke). In comparison with Sado, Niigata patients were younger, with a higher prevalence of comorbidities (hypertension, diabetes, dyslipidemia, and cerebral stroke)., Conclusions: As the proportion of LVSD cases increases progressively with age, it is expected to simulate a future epidemic. The differences between patients' characteristics and disease patterns in urban and rural communities may favor individually tailoring preventive strategies for HF in these areas.