By virtue of the operator Hermite polynomial method and the technique of integration within the ordered product of operators we derive a new kind of special function, which is closely related to one- and two-variable ...By virtue of the operator Hermite polynomial method and the technique of integration within the ordered product of operators we derive a new kind of special function, which is closely related to one- and two-variable Hermite polynomials.Its application in deriving the normalization for some quantum optical states is presented.展开更多
One of the great difficulties in understanding nitrogen plasma elementary processes is the lack of an available database of the cross-sections of electron-impact excitations and radiations. Ab initio calculations of v...One of the great difficulties in understanding nitrogen plasma elementary processes is the lack of an available database of the cross-sections of electron-impact excitations and radiations. Ab initio calculations of vibrational excitation cross sections for electron collisions with nitrogen molecules in low-lying states using similarity function approach, such as a-a＇, a-w, B-B＇ and B-W transition systems, are reported here for the first time. In the meantime, the average excitation energies of neighboring levels of these systems have been calculated. In order to obtain the cross sections, accurate spectroscopic constants and transition dipole moments have been investigated. Potential energy curves and other electronic transition dipole moments for the low-lying states of N2 have been re-evaluated using complete active space self-consistent field （CASSCF） approach with aug-cc-pVqZ basis set. The calculated cross-sections could provide a database for studying the elementary processes and the properties in N2 plasma.展开更多
Since the introduction of total mesorectal excision as the standard approach in mid and low rectal cancer,the incidence of local recurrence has sharply declined.Similar attention to surgical technique in colon cancer(...Since the introduction of total mesorectal excision as the standard approach in mid and low rectal cancer,the incidence of local recurrence has sharply declined.Similar attention to surgical technique in colon cancer(CC) has resulted in the concept of complete mesocolic excision(CME),which consists of complete removal of the intact mesentery and high ligation of the vascular supply at its origin.Although renewed attention to meticulous surgical technique certainly has its merits,routine implementation of CME is currently unfounded.Firstly,in contrast to rectal cancer,local recurrence originating from an incompletely removed mesenteryis rare in CC and usually a manifestation of systemic disease.Secondly,although CME may increase nodal counts and therefore staging accuracy,this is unlikely to affect survival since the observed relationship between nodal counts and outcome in CC is most probably not causal but confounded by a range of clinical variables.Thirdly,several lines of evidence suggest that metastasis to locoregional nodes occurs early and is a stochastic rather than a stepwise phenomenon in CC,in essence reflecting the tumor-host-metastasis relationship.Unsurprisingly,therefore,comparative studies in CC as well as in other digestive cancers have failed to demonstrate any survival benefit associated with extensive,additional or extra-mesenteric lymphadenectomy.Finally,routine implementation of CME may cause patient harm by longer operating times,major vascular damage and autonomic nerve injury.Therefore,data from randomized trials reporting relevant endpoints are required before CME can be recommended as a standard approach in CC surgery.展开更多
励磁故障引起的发电机失磁,将影响电网电压水平和并联运行机组间无功功率的分配,破坏发电机与电网之间的稳定性。以励磁绕组开路失磁为例,利用M AT L A B/S i m u l i n k软件平台,对汽轮发电机失磁物理过程的动态特性进行仿真研究。研...励磁故障引起的发电机失磁,将影响电网电压水平和并联运行机组间无功功率的分配,破坏发电机与电网之间的稳定性。以励磁绕组开路失磁为例,利用M AT L A B/S i m u l i n k软件平台,对汽轮发电机失磁物理过程的动态特性进行仿真研究。研究结果表明:失磁故障时,降负荷至稳态异步越快,越有利于保障发电机的安全运行。展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.11175113)
文摘By virtue of the operator Hermite polynomial method and the technique of integration within the ordered product of operators we derive a new kind of special function, which is closely related to one- and two-variable Hermite polynomials.Its application in deriving the normalization for some quantum optical states is presented.
基金supported by National Natural Science Foundation of China(Nos.11175035,10875023)the National Magnetic Confinement Fusion Science Program of China(No.2013GB109005)+1 种基金Chinesisch-Deutsches Forschungsprojekt(GZ768)the Fundamental Research Fundsfor the Central Universities of China(No.DUT12ZD(G)01)
文摘One of the great difficulties in understanding nitrogen plasma elementary processes is the lack of an available database of the cross-sections of electron-impact excitations and radiations. Ab initio calculations of vibrational excitation cross sections for electron collisions with nitrogen molecules in low-lying states using similarity function approach, such as a-a＇, a-w, B-B＇ and B-W transition systems, are reported here for the first time. In the meantime, the average excitation energies of neighboring levels of these systems have been calculated. In order to obtain the cross sections, accurate spectroscopic constants and transition dipole moments have been investigated. Potential energy curves and other electronic transition dipole moments for the low-lying states of N2 have been re-evaluated using complete active space self-consistent field （CASSCF） approach with aug-cc-pVqZ basis set. The calculated cross-sections could provide a database for studying the elementary processes and the properties in N2 plasma.
基金Supported by The Fund for Scientific Research-Flanders(FWO)to Ceelen W(Senior Clinical Researcher)
文摘Since the introduction of total mesorectal excision as the standard approach in mid and low rectal cancer,the incidence of local recurrence has sharply declined.Similar attention to surgical technique in colon cancer(CC) has resulted in the concept of complete mesocolic excision(CME),which consists of complete removal of the intact mesentery and high ligation of the vascular supply at its origin.Although renewed attention to meticulous surgical technique certainly has its merits,routine implementation of CME is currently unfounded.Firstly,in contrast to rectal cancer,local recurrence originating from an incompletely removed mesenteryis rare in CC and usually a manifestation of systemic disease.Secondly,although CME may increase nodal counts and therefore staging accuracy,this is unlikely to affect survival since the observed relationship between nodal counts and outcome in CC is most probably not causal but confounded by a range of clinical variables.Thirdly,several lines of evidence suggest that metastasis to locoregional nodes occurs early and is a stochastic rather than a stepwise phenomenon in CC,in essence reflecting the tumor-host-metastasis relationship.Unsurprisingly,therefore,comparative studies in CC as well as in other digestive cancers have failed to demonstrate any survival benefit associated with extensive,additional or extra-mesenteric lymphadenectomy.Finally,routine implementation of CME may cause patient harm by longer operating times,major vascular damage and autonomic nerve injury.Therefore,data from randomized trials reporting relevant endpoints are required before CME can be recommended as a standard approach in CC surgery.
文摘励磁故障引起的发电机失磁,将影响电网电压水平和并联运行机组间无功功率的分配,破坏发电机与电网之间的稳定性。以励磁绕组开路失磁为例,利用M AT L A B/S i m u l i n k软件平台,对汽轮发电机失磁物理过程的动态特性进行仿真研究。研究结果表明:失磁故障时,降负荷至稳态异步越快,越有利于保障发电机的安全运行。
