A negative example shows that the model given by Mason Iri is used to prove that the relationship between the minimum flow problem and the Hamiltonian path problem in a (directed) network, is not rigorous. A new model...A negative example shows that the model given by Mason Iri is used to prove that the relationship between the minimum flow problem and the Hamiltonian path problem in a (directed) network, is not rigorous. A new model called minimum spanning flow in a network is established to revise the old one. It is proved that the problem of determining whether there is a Hamiltonian path from a specified vertex s to another t on a given digraph can be reducible at polynomial time to the problem of constructing a minimum spanning flow in a two-terminal extended network s,t , with the unit capacity for all arcs.展开更多
Objective: To study the causes and value of the pseudo-occlusion of the anastoraotic pathway between celiac and superior mesenteric arteries. Methods: 15 patients including 12 patients with hepatocellular carcinoma an...Objective: To study the causes and value of the pseudo-occlusion of the anastoraotic pathway between celiac and superior mesenteric arteries. Methods: 15 patients including 12 patients with hepatocellular carcinoma and 3 patients with hepatic hemangioma underwent superior mesenteric arteriography (SMA) and celiac arteriography (CA) in interventional therapy. The angiographic features of the 15 cases were dynamically observed by 2 experienced radiologists in double-blind manner. Results: Similar interpretations were given by the 2 radiologists. In CA, pseudo-occlusion occurred at the bifurcation of the common hepatic artery and the celiac artery in 8 cases, at the bifurcation of the common hepatic artery and the gastroduodenal artery in 6 cases and at the bifurcation of the right hepatic artery and the celiac artery in 1 case. No occlusion was found in SMA and the angiographic wire and catheter could pass easily through the occluded regions seen in CA. Conclusion: Pseudo occlusion of the anastomotic pathway between the superior mesenteric and celiac arteries is rare phenomenon. Its cause was not identified in our cases. It may result from the hemodynamic change or abnormality of the hepatic artery. It is very important to understand the existence of pseudo-occlusion in order to guide the catheterization in interventional therapy.展开更多
文摘A negative example shows that the model given by Mason Iri is used to prove that the relationship between the minimum flow problem and the Hamiltonian path problem in a (directed) network, is not rigorous. A new model called minimum spanning flow in a network is established to revise the old one. It is proved that the problem of determining whether there is a Hamiltonian path from a specified vertex s to another t on a given digraph can be reducible at polynomial time to the problem of constructing a minimum spanning flow in a two-terminal extended network s,t , with the unit capacity for all arcs.
文摘Objective: To study the causes and value of the pseudo-occlusion of the anastoraotic pathway between celiac and superior mesenteric arteries. Methods: 15 patients including 12 patients with hepatocellular carcinoma and 3 patients with hepatic hemangioma underwent superior mesenteric arteriography (SMA) and celiac arteriography (CA) in interventional therapy. The angiographic features of the 15 cases were dynamically observed by 2 experienced radiologists in double-blind manner. Results: Similar interpretations were given by the 2 radiologists. In CA, pseudo-occlusion occurred at the bifurcation of the common hepatic artery and the celiac artery in 8 cases, at the bifurcation of the common hepatic artery and the gastroduodenal artery in 6 cases and at the bifurcation of the right hepatic artery and the celiac artery in 1 case. No occlusion was found in SMA and the angiographic wire and catheter could pass easily through the occluded regions seen in CA. Conclusion: Pseudo occlusion of the anastomotic pathway between the superior mesenteric and celiac arteries is rare phenomenon. Its cause was not identified in our cases. It may result from the hemodynamic change or abnormality of the hepatic artery. It is very important to understand the existence of pseudo-occlusion in order to guide the catheterization in interventional therapy.
