Focal nodular hyperplasia(FNH) of the liver is a benign lesion occurring in 0.6%-3% of the general population that probably reflects a local hyperplastic response of hepatocytes to a vascular abnormality. Most lesions...Focal nodular hyperplasia(FNH) of the liver is a benign lesion occurring in 0.6%-3% of the general population that probably reflects a local hyperplastic response of hepatocytes to a vascular abnormality. Most lesions are diagnosed incidentally and the natural history of the disease remains largely unknown. It has been shown that most FNH remain stable, or even regress, over a long follow-up period. We present a patient with FNH of the liver who was followed up for 7 years. A 26-yearold woman with a 5-year history of oral contraceptive use was referred to our hospital in February 2005 for further examination of a liver tumour. The diagnosis of FNH was made using magnetic resonance(MR) imaging with hepatospecific contrast media; this technique allows a correct diagnosis, in particular distinguishing FNH from hepatic adenoma, avoiding an invasive procedure such as the lesion biopsy. After 7-year from the diagnosis, we observed the complete spontaneous regression of the lesion by enhanced MR scanning. In this patient, discontinuation of oral contraceptive use and two childbirths may have influenced the natural history of FNH. To our knowledge, in the English literature there is no report illustrating a complete regression of giant FNH but only studies of decreasing in size. The present case suggests that a young patient with giant FNH should be managed conservatively rather than by resection, because FNH has the potential for spontaneous regression.展开更多
Cooperative path planning is an important area in fixed-wing UAV swarm.However,avoiding multiple timevarying obstacles and avoiding local optimum are two challenges for existing approaches in a dynamic environment.Fir...Cooperative path planning is an important area in fixed-wing UAV swarm.However,avoiding multiple timevarying obstacles and avoiding local optimum are two challenges for existing approaches in a dynamic environment.Firstly,a normalized artificial potential field optimization is proposed by reconstructing a novel function with anisotropy in each dimension,which can make the flight speed of a fixed UAV swarm independent of the repulsive/attractive gain coefficient and avoid trapping into local optimization and local oscillation.Then,taking into account minimum velocity and turning angular velocity of fixed-wing UAV swarm,a strategy of decomposing target vector to avoid moving obstacles and pop-up threats is proposed.Finally,several simulations are carried out to illustrate superiority and effectiveness.展开更多
文摘Focal nodular hyperplasia(FNH) of the liver is a benign lesion occurring in 0.6%-3% of the general population that probably reflects a local hyperplastic response of hepatocytes to a vascular abnormality. Most lesions are diagnosed incidentally and the natural history of the disease remains largely unknown. It has been shown that most FNH remain stable, or even regress, over a long follow-up period. We present a patient with FNH of the liver who was followed up for 7 years. A 26-yearold woman with a 5-year history of oral contraceptive use was referred to our hospital in February 2005 for further examination of a liver tumour. The diagnosis of FNH was made using magnetic resonance(MR) imaging with hepatospecific contrast media; this technique allows a correct diagnosis, in particular distinguishing FNH from hepatic adenoma, avoiding an invasive procedure such as the lesion biopsy. After 7-year from the diagnosis, we observed the complete spontaneous regression of the lesion by enhanced MR scanning. In this patient, discontinuation of oral contraceptive use and two childbirths may have influenced the natural history of FNH. To our knowledge, in the English literature there is no report illustrating a complete regression of giant FNH but only studies of decreasing in size. The present case suggests that a young patient with giant FNH should be managed conservatively rather than by resection, because FNH has the potential for spontaneous regression.
文摘Cooperative path planning is an important area in fixed-wing UAV swarm.However,avoiding multiple timevarying obstacles and avoiding local optimum are two challenges for existing approaches in a dynamic environment.Firstly,a normalized artificial potential field optimization is proposed by reconstructing a novel function with anisotropy in each dimension,which can make the flight speed of a fixed UAV swarm independent of the repulsive/attractive gain coefficient and avoid trapping into local optimization and local oscillation.Then,taking into account minimum velocity and turning angular velocity of fixed-wing UAV swarm,a strategy of decomposing target vector to avoid moving obstacles and pop-up threats is proposed.Finally,several simulations are carried out to illustrate superiority and effectiveness.
