Accumulation is a fundamental process in dynamic systems: inventory accumulates production less shipments; the national debt accumulates the federal deficit. Effective decision making in such systems requires an understanding of the relationship between stocks and the flows that alter them. However, highly educated people are often unable to infer the behavior of simple stock-flow systems. Poor...

The Lucas-Kanade tracker has proven to be an efficient and accurate method for calculation of the optical flow. However, this algorithm can reliably track only suitable image features like corners and edges. Therefore, the optical flow can only be calculated for a few points in each image, resulting in sparse optical flow fields. Accumulation of these vectors over time is a suitable method to r...

The clinical hallmarks of hibernating myocardium include hypocontractility while retaining an inotropic reserve (using dobutamine echocardiography), having normal or increased [18F]fluoro-2-deoxyglucose-6-phosphate (18FDG6P) accumulation associated with decreased coronary flow [flow-metabolism mismatch by positron emission tomography (PET)], and recovering completely postrevascularization. In t...

In this paper, we study the asymptotic behavior of an AQM router serving many AIMD flows. Our model for the AQM router is general and covers most AQM schemes in the current literature. We use a window-based model for the AIMD flows. When the number of AIMD flows is large, we show that the system converges point wise to a limit model. Further, under certain technical conditions, we prove that th...

IP multicast is gaining acceptance among service providers as the protocols and infrastructure mature. Yet characteristics of multicast traffic remain poorly understood. Using passive OC-12 monitors we observe multicast traffic on links connecting aggregated customers and peer networks to our native multicast backbone network. We first refine existing traffic flow profiling methodologies via an...

plicated processes on the wheel surf ace along the wheel width. In order to make these processes clear, the experimental analysis of traverse grinding was conducted by widely changing the speed ratio, Kv, the setting depth of wheel, ‡TMT, and the number of total steps, m, (the ratio of the wheel width over the traverse feed per one revolution of the workpiece). The following results were obtain...

Monitoring tissue hypoxia in critically ill patients is a challenging task. Tissue PCO2 has long been proposed as a marker of tissue hypoxia, although there is considerable controversy on whether the rise in CO2 with hypoxia is caused by anaerobic metabolism and excess CO2 production or by the accumulation of aerobically produced CO2 in the setting of blood flow stagnation. The prevention of in...

A mathematical model of the rat collecting duct (CD) has been developed by concatenating previously published models of cortical (Weinstein AM. Am J Physiol Renal Physiol 280: F1072-F1092, 2001); outer medullary (Weinstein AM. Am J Physiol Renal Physiol 279: F24-F45, 2000); and inner medullary segments (Weinstein AM. Am J Physiol Renal Physiol 274: F841-F855, 1998). Starting with end-distal tub...

Atherosclerosis is inflammation of the vessel wall of the arterial tree. This inflammation arises at specific areas that experience disturbed blood flow such as bifurcations and the lesser curvature of the aortic arch. Although all endothelial cells are exposed to comparable levels of circulating plasma cholesterol, only endothelial cells overlaying lesions display an inflamed phenotype. This o...