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With the deployment of IPTV reliability for multicast is becoming an important research topic again. Even though it has been intensively investigated before, there is now an understanding of the deployment scenario and the application requirements that allows solutions to be evaluated in detail. We describe how to design a fast retransmission cache based on recent extensions of RTP. We have implemented a prototype intended for deployment in an access node and explain the necessary trade-offs in the design. The paper also contains a performance evaluation which shows the efficiency of the retransmission functionality to handle losses and its performance in congested networks.

The function of a device for frequency filtration of roentgenograms with digital filters has been tested with the use of different filters. The image was altered in the expected way, which means that the device is suitable for investigating the possibilities of different filters to improve the diagnostic ability. The results of the tests indicate that improvement should be achieved by low-pass filtration.

The potential value of positron emission tomography (PET) in evaluating the myocardial energy metabolism was studied in two previously healthy mini-pigs before, during and after the induction of non-insulin dependent diabetes with alloxan. The distribution and kinetics of radioactivity derived from trace amounts of 11C-pyruvate and 1-11C-palmitate were followed in different sections of the myocardium. The early distribution of both tracers was similar even after the development of diabetes. The elimination of 11C-pyruvate derived radioactivity was slower in the diabetic heart. The rate of beta-oxidation was also decreased as suggested by the elimination curve of 11C-palmitate and the incorporation of 11C-palmitate into the triglyceride and phospholipid pool of the myocardium was increased in the diabetic animals. The results are consistent with previous observations using other techniques. Positron emission tomography offers the opportunity to characterize regional tissue metabolism quantitatively in vivo. This method may become a powerful tool in studying myocardial metabolism and the metabolic basis for the cardiac dysfunction in diabetes mellitus.