The evolution of self organized Ge quantum dots structure is investigated by scanning tunneling microscopy and atomic force microscopy during annealing treatment up to 700℃ in an ultra high vacuum(UHV) system.When t...The evolution of self organized Ge quantum dots structure is investigated by scanning tunneling microscopy and atomic force microscopy during annealing treatment up to 700℃ in an ultra high vacuum(UHV) system.When the sample temperature rises to 630℃,a great amount of new dots emerge on the wetting layer,which are believed to be incoherent islands compared with the dislocation free coherent islands formed during molecular beam epitaxy growth.展开更多
Objective： The aim of the study was to investigate CT and MRI findings of parotid Warthin＇s tumors （parotid ad- enolymphomas）. Methods： CT and MRI findings of 14 patients with pathologically-confirmed Warthin＇s ...Objective： The aim of the study was to investigate CT and MRI findings of parotid Warthin＇s tumors （parotid ad- enolymphomas）. Methods： CT and MRI findings of 14 patients with pathologically-confirmed Warthin＇s tumor （10 males and 4 females） were retrospectively analyzed. The average age was 56 years （range 44-77 years）. Twelve patients underwent CT plain scan, of which, 10 received the further enhancement; other 2 patients performed MR plain scan, of which, 1 was enhanced. The disease course ranged from 20 days to 4 years with the average of 22 months. Ten patients had the smoking history （71.4%）. Results： A total of 22 foal were found in all 14 patients, multiple in one parotid gland in 3 patients, single in one parotid gland in 9 patients and single in bilateral glands in 2 patients （one recurred the tumor in the contralateral gland 14 years after the surgery）. Sixteen （72.7%） foci or the main bodies [long diameter of 0.8-5.0 crn with the average of （2.3 ＋ 1.3） crn] were located in the posterior and interior role of the superficial lobe of the parotid gland. The foci were round or oval. The boundary was smooth in 21 （95.5%） loci and blurred in 3 loci which were proved by biopsy to be accompanied with infection. Fourteen foci （77.7%） with uniform density and 4 foci with nonuniform density were found in 12 patients under CT plain. A total of 15 loci in 10 patients were enhanced, 7 （46.7%） on significant enhancement, 5 （33.3%） on moderate enhancement and 3 on slight enhancement. The margin was enhanced slightly in 3 foci. In MR images, the signal of tumor was uniform or nonunifrom, TlWl showed low signal and T2Wl showed moderate or high signal. The envelope displayed signal shadow under plain scan and the enhancement was slightly. Conclusion： For middle or elder males with the smoking history, if they have the foci in the posterior and interior parts of the parotid gland which show clear boundary and significant enhancement, especially for multiple or bilateral foci, parotid Warthin＇s tumor should be considered firstly.展开更多
Using the configuration-integration methods （CI） [Phys. Rev. B 45 （1992） 19], we report the results of the Hydrogenie-impurity ground state in a GaAs/AIAs spherical quantum dot under an electric field. We discuss ...Using the configuration-integration methods （CI） [Phys. Rev. B 45 （1992） 19], we report the results of the Hydrogenie-impurity ground state in a GaAs/AIAs spherical quantum dot under an electric field. We discuss the variations of the binding energies of the Hydrogenic-impurity ground state as a function of the position of impurity D, the radius R of the quantum dot, and also as a function of electric field F. We find that the ground energy and binding energy of impurity placed anywhere depend strongly on the position of impurity. Also, electric field can largely change the Hydrogenic-impurity ground state only limiting to the big radius of quantum dot. And the differences in energy level and binding energy are observed from the center donor and off-center donor.展开更多
This paper presents a new graph-based single-copy routmg method m delay tolerant networks （DTN）. With time goes on in the networks, a DTN connectivity graph is constituted with mobility of nodes and communication, a...This paper presents a new graph-based single-copy routmg method m delay tolerant networks （DTN）. With time goes on in the networks, a DTN connectivity graph is constituted with mobility of nodes and communication, and a corresponding greedy tree is obtained using a greedy algorithm in DTN connectivity graph. While there are some bad nodes such as disabled nodes or selfish nodes in delay tolerant networks, the nodes can choose the next p^oper intermediate node to transmit the mes- sage by comparing the location of neighboring nodes in the greedy tree. The single-copy routing method is very appropriate for energy-constrained, storage-constrained and bandwidth-constrained applications such as mobile wireless DTN networks. We show that delivery ratio is increased significantly by using the graph-based single-copy routing when bad nodes exist.展开更多
文摘The evolution of self organized Ge quantum dots structure is investigated by scanning tunneling microscopy and atomic force microscopy during annealing treatment up to 700℃ in an ultra high vacuum(UHV) system.When the sample temperature rises to 630℃,a great amount of new dots emerge on the wetting layer,which are believed to be incoherent islands compared with the dislocation free coherent islands formed during molecular beam epitaxy growth.
文摘Objective： The aim of the study was to investigate CT and MRI findings of parotid Warthin＇s tumors （parotid ad- enolymphomas）. Methods： CT and MRI findings of 14 patients with pathologically-confirmed Warthin＇s tumor （10 males and 4 females） were retrospectively analyzed. The average age was 56 years （range 44-77 years）. Twelve patients underwent CT plain scan, of which, 10 received the further enhancement; other 2 patients performed MR plain scan, of which, 1 was enhanced. The disease course ranged from 20 days to 4 years with the average of 22 months. Ten patients had the smoking history （71.4%）. Results： A total of 22 foal were found in all 14 patients, multiple in one parotid gland in 3 patients, single in one parotid gland in 9 patients and single in bilateral glands in 2 patients （one recurred the tumor in the contralateral gland 14 years after the surgery）. Sixteen （72.7%） foci or the main bodies [long diameter of 0.8-5.0 crn with the average of （2.3 ＋ 1.3） crn] were located in the posterior and interior role of the superficial lobe of the parotid gland. The foci were round or oval. The boundary was smooth in 21 （95.5%） loci and blurred in 3 loci which were proved by biopsy to be accompanied with infection. Fourteen foci （77.7%） with uniform density and 4 foci with nonuniform density were found in 12 patients under CT plain. A total of 15 loci in 10 patients were enhanced, 7 （46.7%） on significant enhancement, 5 （33.3%） on moderate enhancement and 3 on slight enhancement. The margin was enhanced slightly in 3 foci. In MR images, the signal of tumor was uniform or nonunifrom, TlWl showed low signal and T2Wl showed moderate or high signal. The envelope displayed signal shadow under plain scan and the enhancement was slightly. Conclusion： For middle or elder males with the smoking history, if they have the foci in the posterior and interior parts of the parotid gland which show clear boundary and significant enhancement, especially for multiple or bilateral foci, parotid Warthin＇s tumor should be considered firstly.
基金Supported by the National Natural Science Foundation of China under Grant No.10775035
文摘Using the configuration-integration methods （CI） [Phys. Rev. B 45 （1992） 19], we report the results of the Hydrogenie-impurity ground state in a GaAs/AIAs spherical quantum dot under an electric field. We discuss the variations of the binding energies of the Hydrogenic-impurity ground state as a function of the position of impurity D, the radius R of the quantum dot, and also as a function of electric field F. We find that the ground energy and binding energy of impurity placed anywhere depend strongly on the position of impurity. Also, electric field can largely change the Hydrogenic-impurity ground state only limiting to the big radius of quantum dot. And the differences in energy level and binding energy are observed from the center donor and off-center donor.
基金Supported by the National High Technology Research and Development Programme of China （No. 2007AA01Z429, 2007AA01Z405 ） and the National Natural Science Foundation of China （No. 60633020, 60702059, 60872041 ）.
文摘This paper presents a new graph-based single-copy routmg method m delay tolerant networks （DTN）. With time goes on in the networks, a DTN connectivity graph is constituted with mobility of nodes and communication, and a corresponding greedy tree is obtained using a greedy algorithm in DTN connectivity graph. While there are some bad nodes such as disabled nodes or selfish nodes in delay tolerant networks, the nodes can choose the next p^oper intermediate node to transmit the mes- sage by comparing the location of neighboring nodes in the greedy tree. The single-copy routing method is very appropriate for energy-constrained, storage-constrained and bandwidth-constrained applications such as mobile wireless DTN networks. We show that delivery ratio is increased significantly by using the graph-based single-copy routing when bad nodes exist.
