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As foremost sensors of ambient conditions, temperature sensors are regarded as the most vital ones in wide-ranging applications touching the societal life. Amongst the temperature sensors, NTC thermistors have captured their unique place due to the favorable metrics such as highest sensitivity, low cost, and ease of deployment. Transition metal oxides especially the NixMnxOx are widely used for thermistor synthesis in spite of the main difficulty of predicting the final sensor characteristics before the actual synthesis. In view of the above, we report an Artificial Neural Network (ANN) technique to accomplish the synthesis with predictable results saving valuable resources. In the said ANN modeling we use hyperbolic tangent sigmoid transfer function for input layer and linear transfer function for the output layer. Leven- berg-Marquardt feed-forward algorithm trains the neural net. We measure the performance of the ANN model with regard to mean square error (MSE) and the correlation coefficient between expected output and output provided by the network. Moreover, we uniquely model the resistance-temperature (R-T) characteristics of different thermistor samples using optimized ANN structure. To model such sort of behavior, we provide nickel content, room temperature resistance, and concentration of oxalic acid as an input data to the network and predict the nickel acetate and manganese acetate concentration. The accomplished ANN modeling evidences a lower number of hidden neuron architecture exhibiting optimum performance as regards to prediction accuracy. The lower number of hidden neurons signifies a lesser amount of memory required for prediction of different chemical composition. Thus, we demonstrate exploitation of modeling, simulation and soft computational approaches for predicting the best suitable chemical composition and thus establish the synergy between the materials science and soft computing paradigm. [ABSTRACT FROM AUTHOR]

To map precise myocardial perfusion anatomy, we correlated detailed coronary arteriographic anatomy for every coronary artery and all secondary branches in the heart that had flow-limiting stenosis with corresponding specific, circumscribed, myocardial perfusion defects by positron emission tomography. Eight hundred ninety-five patients with abnormal coronary arteriograms showing any visible coronary artery narrowing of greater than 10% diameter stenosis underwent positron emission tomography perfusion imaging at rest and after dipyridamole stress; the data obtained were processed automatically into 3-dimensional topographic displays of relative radionuclide uptake in anterior, septal, left lateral, and inferior quadrant views, without attenuation artifacts, depth-dependent resolution, or spatial distortion of polar displays. The selection criterion for detailed anatomic analysis was the presence of a discrete, localized, moderate to severe, dipyridamole-induced perfusion defect, defined by automated algorithms as 1 quadrant view outside 2 SDs of healthy control subjects with which a specific stenotic coronary artery and/or its secondary branches could be correlated unequivocally on the coronary arteriogram for mapping precise perfusion anatomy, not for determining sensitivity or specificity. Because the anatomy of myocardial perfusion is inherently not statistical data, the results are presented as a summary atlas and series of individual cases that illustrate myocardial perfusion anatomy. Because the patterns of myocardial perfusion anatomy were derived from a large number of subjects, the atlas provides generalized information, not previously published, that correlates detailed arteriographic anatomy with perfusion anatomy including secondary diagonal, marginal, and posterior descending branches of the coronary arteries. [ABSTRACT FROM AUTHOR]

Occurrence of cerebrovascular accidents has been associated with cocaine abuse. We investigated the relative distribution of cerebral blood flow (CBF) in groups of chronic cocaine users, and of normal controls. Relative CBF was measured using positron emission tomography and 15 oxygen-labelled water. The cocaine users showed areas of deranged CBF as evidenced by patchy regions of defective isotope accumulation throughout their brain. The chronic cocaine users showed decreased relative CBF in the prefrontal cortex when compared with normal subjects. The repeated scans of some cocaine users, after 10 days of cocaine withdrawal, continued to show decreased relative CBF of the prefrontal cortex. We hypothesise that some of the widespread defects in CBF in the cocaine users could reflect the effects of vasospasm in cerebral arteries exposed chronically to the sympathomimetic actions of cocaine. [ABSTRACT FROM AUTHOR]

Objectives: The purpose of this study was to determine if combined intense lifestyle and pharmacologic lipid treatment reduce myocardial perfusion abnormalities and coronary events in comparison to usual-care cholesterol-lowering drugs and whether perfusion changes predict outcomes.Background: Lifestyle and lipid drugs separately benefit patients with coronary artery disease (CAD).Methods: A total of 409 patients with CAD, who underwent myocardial perfusion imaging by dipyridamole positron emission tomography at baseline and after 2.6 years, had quantitative size/severity of perfusion defects measured objectively by automated software with follow-up for five additional years for coronary artery bypass graft, percutaneous coronary intervention, myocardial infarction, or cardiac death. Patients were categorized blindly according to prospective, predefined criteria as "poor" treatment without diet or lipid drugs, or smoking; "moderate" treatment on American Heart Association diet and lipid-lowering drugs or on strict low-fat diet (<10% of calories) without lipid drugs; and "maximal" treatment with diet <10% of calories as fat, regular exercise, and lipid active drugs dosed to target goals of low-density lipoproteins <2.3 mmol/l (90 mg/dl), high-density lipoproteins >1.2 mmol/l (45 mg/dl), and triglycerides <1.1 mmol/l (100 mg/dl).Results: Over five years, coronary events occurred in 6.6%, 20.3%, and 30.6% of patients on maximal, moderate, and poor treatment, respectively (p = 0.001). Size/severity of perfusion abnormalities significantly decreased for patients receiving maximal treatment and increased for patients undergoing moderate and poor treatment (p = 0.003 and 0.0001, respectively). Combined intense lifestyle change plus lipid active drugs and severity/change of perfusion abnormalities independently predicted cardiac events.Conclusions: Intense lifestyle and pharmacologic lipid treatment reduce size/severity of myocardial perfusion abnormalities and cardiac events compared with usual-care cholesterol-lowering drugs. Perfusion changes parallel treatment intensity and predict outcomes. [ABSTRACT FROM AUTHOR]