Objective To estimate the probability of unprotected heterosexual vaginal transmission of HIV-1 from clients to Female Sex Workers (FSWs) in Kaiyuan County, Yunnan province, China, and analyze factors which impact t...Objective To estimate the probability of unprotected heterosexual vaginal transmission of HIV-1 from clients to Female Sex Workers (FSWs) in Kaiyuan County, Yunnan province, China, and analyze factors which impact the transmission probability. Methods An open cohort research of FSWs in Kaiyuan was created from surveys conducted in April 2008, October 2008, and April 2009. Two cross-sectional surveys of local clients were also carried out in May 2008 and November 2008. A model was developed to estimate the probability of unprotected heterosexual vaginal transmission of HIV-1 from clients to FSWs. Results The transmission probability from clients to FSWs was estimated as 0.0023 [95% CI 0.0014-0.0032] per unprotected heterosexual act. Conclusion The transmission probability among this group engaging in commercial sex in Yunnan province differs from that found in studies from other countries, and future studies should estimate the influence factors of HIV-1 transmission probability, such as stage of HIV infection, co-morbid sexually transmitted infections (STIs).展开更多
This paper calculates the lifetime of resonant state and transmission probability of a single electron tunnelling in a spherical quantum dot (SQD) structure by using the transfer matrix technique. In the SQD, the el...This paper calculates the lifetime of resonant state and transmission probability of a single electron tunnelling in a spherical quantum dot (SQD) structure by using the transfer matrix technique. In the SQD, the electron is confined both transversally and longitudinally, the motion in the transverse and longitudinal directions is separated by using the adiabatic approximation theory. Meanwhile, the energy levels of the former are considered as the effective confining potential. The numerical calculations are carried out for the SQD consisting of GaAs/InAs material. The obtained results show that the bigger radius of the quantum dot not only leads significantly to the shifts of resonant peaks toward the low-energy region, but also causes the lengthening of the lifetime of resonant state. The lifetime of resonant state can be calculated from the uncertainty principle between the energy half width and lifetime.展开更多
We study electrons tunneling through a double-magnetic-barrier structure on the surface of monolayer graphene. The transmission probability and the conductance are calculated by using the transfer matrix method. The r...We study electrons tunneling through a double-magnetic-barrier structure on the surface of monolayer graphene. The transmission probability and the conductance are calculated by using the transfer matrix method. The results show that the normal incident transmission probability is blocked by the magnetic vector potential and the Klein tunneling region depends strongly on the direction of the incidence electron. The transmission probability and the conductance can be modulated by changing structural parameters of the barrier, such as width and height, offering a possibility to control electron beams on graphene.展开更多
Within the framework of the Floquet theorem, we have investigated single-electron photon-assisted tunneling in a double-well system using the transfer matrix technique. The transmission probability displays satellite ...Within the framework of the Floquet theorem, we have investigated single-electron photon-assisted tunneling in a double-well system using the transfer matrix technique. The transmission probability displays satellite peaks on both sides of the main resonance peaks and these satellite peaks originate from emission or absorption photons. The single-electron resonance tunneling can be controlled through changing the applied harmonically potential positions, such as driven potential in wells, in barriers, or in whole double-well systems. This advantage should be useful in the optimization of the parameters of a transmission device.展开更多
In the ring-shaped Su–Schrieffer–Heeger(SSH)double-chain,the quantum interference between the two different electron tunneling paths of the upper and lower chains has an important influence on the electron transport...In the ring-shaped Su–Schrieffer–Heeger(SSH)double-chain,the quantum interference between the two different electron tunneling paths of the upper and lower chains has an important influence on the electron transport properties of non-trivial topological edge states.Here,we have studied the electron transport signatures of non-trivial topological edge states in a ring-shaped SSH double-chain system based on the wave-guide theory and transfer-matrix method.In the ringshaped SSH double-chain with the upper chain being different from the lower one,it is demonstrated that the electron transmission probability displays the four and two resonance peaks associated with the non-trivial topological edge states in the weak and strong coupling regimes,respectively.Whereas in the case of the upper chain being the same as the lower one,the two transmission resonance peaks associated with the non-trivial topological edge states in the weak coupling regime are only found,and that in the strong coupling regime disappear that originated from the destructive interference between the two different electron tunneling paths of the upper and lower chains.Consequently,the variation of the number of transmission resonance peaks associated with the non-trivial topological edge states in the weak and strong coupling regimes suggests that an alternative scheme for detecting non-trivial topological edge states in the ring-shaped SSH doublechain system.展开更多
Caching popular content in the storage of small cells is deemed as an efficient way to decrease latency, offload backhaul and satisfy user's demands. In order to investigate the performance of cache-enabled small cel...Caching popular content in the storage of small cells is deemed as an efficient way to decrease latency, offload backhaul and satisfy user's demands. In order to investigate the performance of cache-enabled small cell networks, coverage probability is studied in both single-point transmission and cooperative multipoint(Co MP) transmission scenarios. Meanwhile, the caching distribution modeled as Zipf and uniform distribution are both considered. Assuming that small base stations(SBSs) are distributed as a homogeneous Poisson point process(HPPP), the closed-form expressions of coverage probability are derived in different transmission cases. Simulation results show that Co MP transmission achieves a higher coverage probability than that of single-point transmission. Furthermore, Zipf distribution-based caching is more preferable than uniform distribution-based caching in terms of coverage probability.展开更多
基金supported by the mega-projects of national science research for the 11th Five-Year Plan of China (2008ZX10001-003)
文摘Objective To estimate the probability of unprotected heterosexual vaginal transmission of HIV-1 from clients to Female Sex Workers (FSWs) in Kaiyuan County, Yunnan province, China, and analyze factors which impact the transmission probability. Methods An open cohort research of FSWs in Kaiyuan was created from surveys conducted in April 2008, October 2008, and April 2009. Two cross-sectional surveys of local clients were also carried out in May 2008 and November 2008. A model was developed to estimate the probability of unprotected heterosexual vaginal transmission of HIV-1 from clients to FSWs. Results The transmission probability from clients to FSWs was estimated as 0.0023 [95% CI 0.0014-0.0032] per unprotected heterosexual act. Conclusion The transmission probability among this group engaging in commercial sex in Yunnan province differs from that found in studies from other countries, and future studies should estimate the influence factors of HIV-1 transmission probability, such as stage of HIV infection, co-morbid sexually transmitted infections (STIs).
基金Project supported by the National Nature Science Foundation of China (Grant No 10347004).
文摘This paper calculates the lifetime of resonant state and transmission probability of a single electron tunnelling in a spherical quantum dot (SQD) structure by using the transfer matrix technique. In the SQD, the electron is confined both transversally and longitudinally, the motion in the transverse and longitudinal directions is separated by using the adiabatic approximation theory. Meanwhile, the energy levels of the former are considered as the effective confining potential. The numerical calculations are carried out for the SQD consisting of GaAs/InAs material. The obtained results show that the bigger radius of the quantum dot not only leads significantly to the shifts of resonant peaks toward the low-energy region, but also causes the lengthening of the lifetime of resonant state. The lifetime of resonant state can be calculated from the uncertainty principle between the energy half width and lifetime.
基金Project supported by the National Natural Science Foundation of China (Grant No.10974043)the Natural Science Foundation of Hebei Province of China (Grant No.A2009000240)
文摘We study electrons tunneling through a double-magnetic-barrier structure on the surface of monolayer graphene. The transmission probability and the conductance are calculated by using the transfer matrix method. The results show that the normal incident transmission probability is blocked by the magnetic vector potential and the Klein tunneling region depends strongly on the direction of the incidence electron. The transmission probability and the conductance can be modulated by changing structural parameters of the barrier, such as width and height, offering a possibility to control electron beams on graphene.
文摘Within the framework of the Floquet theorem, we have investigated single-electron photon-assisted tunneling in a double-well system using the transfer matrix technique. The transmission probability displays satellite peaks on both sides of the main resonance peaks and these satellite peaks originate from emission or absorption photons. The single-electron resonance tunneling can be controlled through changing the applied harmonically potential positions, such as driven potential in wells, in barriers, or in whole double-well systems. This advantage should be useful in the optimization of the parameters of a transmission device.
基金supported by the National Natural Science Foundation of China(Grant No.11974153)the Natural Science Foundation of Shanxi Province,China(Grant No.20210302123184)+1 种基金the Program for the Outstanding Innovative Teams of Higher Learning Institutions of Shanxi Province,China(Grant No.163220120-S)the Natural Science Foundation of Shandong Province,China(Grant No.ZR2020MA091)。
文摘In the ring-shaped Su–Schrieffer–Heeger(SSH)double-chain,the quantum interference between the two different electron tunneling paths of the upper and lower chains has an important influence on the electron transport properties of non-trivial topological edge states.Here,we have studied the electron transport signatures of non-trivial topological edge states in a ring-shaped SSH double-chain system based on the wave-guide theory and transfer-matrix method.In the ringshaped SSH double-chain with the upper chain being different from the lower one,it is demonstrated that the electron transmission probability displays the four and two resonance peaks associated with the non-trivial topological edge states in the weak and strong coupling regimes,respectively.Whereas in the case of the upper chain being the same as the lower one,the two transmission resonance peaks associated with the non-trivial topological edge states in the weak coupling regime are only found,and that in the strong coupling regime disappear that originated from the destructive interference between the two different electron tunneling paths of the upper and lower chains.Consequently,the variation of the number of transmission resonance peaks associated with the non-trivial topological edge states in the weak and strong coupling regimes suggests that an alternative scheme for detecting non-trivial topological edge states in the ring-shaped SSH doublechain system.
基金supported by National Natural Science Foundation of China (61302081)the National Hi-Tech Research and Development Program of China (2014AA01A701)
文摘Caching popular content in the storage of small cells is deemed as an efficient way to decrease latency, offload backhaul and satisfy user's demands. In order to investigate the performance of cache-enabled small cell networks, coverage probability is studied in both single-point transmission and cooperative multipoint(Co MP) transmission scenarios. Meanwhile, the caching distribution modeled as Zipf and uniform distribution are both considered. Assuming that small base stations(SBSs) are distributed as a homogeneous Poisson point process(HPPP), the closed-form expressions of coverage probability are derived in different transmission cases. Simulation results show that Co MP transmission achieves a higher coverage probability than that of single-point transmission. Furthermore, Zipf distribution-based caching is more preferable than uniform distribution-based caching in terms of coverage probability.