Purpose: To study the clinicopathological change on "Multiple Evanescent White-dot Syndrome (MEWDS)"through fundus angiogrphy analyses.Methods:Examing the case with fluorescein angiography (FFA) and indocyan...Purpose: To study the clinicopathological change on "Multiple Evanescent White-dot Syndrome (MEWDS)"through fundus angiogrphy analyses.Methods:Examing the case with fluorescein angiography (FFA) and indocyanine green angiography(ICGA), visual field and following up for 15 months.Results :There exist multiple white dots in the fundus photo and angiography. The changes on ICGA maintain longer than fundus photo and FFA. Papille may be edematous and macula could present with special hypofluorescent flecks.Conclusions:MEWDS has specific angiographic features. Its pathological changes involve deep retinal pigment epithelium(RPE) as well as choroidal capillaries. The prognosis of the visual acuity for MEWDS is very good.展开更多
Dot,line,plane,body are dominant elements for creating visual originality of modern landscapes,among which dot is the fundamental one in the visual design.It is a significant subject in modern landscape design to crea...Dot,line,plane,body are dominant elements for creating visual originality of modern landscapes,among which dot is the fundamental one in the visual design.It is a significant subject in modern landscape design to create visual originality and style of dotted landscapes,and also a premise for humanistic design.The visual characteristics of dotted landscapes were analyzed from the perspectives of style,size,location,configuration and so on.The principles of creating green visual originality for dotted landscapes were concluded,that is,coordination and unification,ratio and scale,balance and stability,rhythm and tempo.Then novel and elegant dotted landscapes can be created by using new materials and techniques,applying deformation,cutting and connection,alternation,distortion and rotation;by adopting motif composition method,motif with outstanding features can be selected as dotted landscapes to form contrast with background and break the rigid atmosphere.展开更多
We have studied the transport properties of a ring-coupled quantum dot array driven by an AC magnetic field, which is connected to two leads, and we give the response of the transport current to the dynamical localiza...We have studied the transport properties of a ring-coupled quantum dot array driven by an AC magnetic field, which is connected to two leads, and we give the response of the transport current to the dynamical localization. We found that when the ratio of the magnetic flux to the total quantum dots number is a root of the zeroth order Bessel function, dynamical localization and collapse of quasi-energy occurs and importantly~ the transport current displays a dip which is the signal of dynamical localization. The dynamical localization effect is strengthened as a result of the increase of the quantum dot number, and it is weakened on account of the increase of the dots-lead hopping rate.展开更多
This paper investigates theoretically the electronic structure and transport of a two-level quantum dot irradiated under a strong laser field at low temperatures. Using the method of Keldysh equation of motion for non...This paper investigates theoretically the electronic structure and transport of a two-level quantum dot irradiated under a strong laser field at low temperatures. Using the method of Keldysh equation of motion for nonequilibrium Green functions, it examines the time-averaged density of states and conductance for the system with photon polarization parallel with and perpendicular to the tunnelling current direction respectively. It is demonstrated that, by analysing some numerical examples, more photon sidebands resonance states and multi-and single-photon transitions are found when diagonal matrix elements dominate the interaction, while the electronic transitions due to multiphoton absorption are more or less suppressed when off-diagonal interaction dominates.展开更多
Using the nonequilibrium Keldysh Green's function technique, the Fano effect of a parallel-coupled triple Rashba quantum dot system is investigated. The conductance as a function of electron energy is numerically cal...Using the nonequilibrium Keldysh Green's function technique, the Fano effect of a parallel-coupled triple Rashba quantum dot system is investigated. The conductance as a function of electron energy is numerically calculated. Compared with the case of a parallel-coupled double quantum dot system, two additional Fano resonance peaks occur in the conductance spectrum. By adjusting the structural parameters, the two Fano resonance peaks may change into the resoaance peaks. In addition, the influence of Rashba spin-orbit interaction on the conductance is studied.展开更多
Using the nonequilibrium Green's function technique,electron transport through a laterally coupled vertical triple quantum dot is investigated.The conductance as a function of electron energy is numerically calculate...Using the nonequilibrium Green's function technique,electron transport through a laterally coupled vertical triple quantum dot is investigated.The conductance as a function of electron energy is numerically calculated.The evolution of the conductance strongly depends on the configuration of dot levels and interdot coupling strengths.展开更多
Using Keldysh nonequilibrium Green function formalism and mapping a many-body electron-phonon interaction onto a one body problem, the electron transport through a serially coupled double quantum dot system is analyze...Using Keldysh nonequilibrium Green function formalism and mapping a many-body electron-phonon interaction onto a one body problem, the electron transport through a serially coupled double quantum dot system is analyzed. The influence of the electron-phonon interaction, temperature, detuning, and interdot tunneling on the transmission coefficient and current is studied. Our results show that the electron-phonon interaction results in the appearance of the side peaks in the transmission coefficient, whose height is strongly dependent on the phonon temperature. We have also found that the inequality of the electron-phonon interaction strength in two dots gives rise to an asymmetry in the current-voltage characteristic. In addition, the temperature difference between the phonon and electron subsystems results in the reduction of the saturated current and the destruction of the step-like behavior of the current. It is also observed that the detuning can improve the magnitude of the current by compensating the mismatch of the quantum dots energy levels induced by the electron-phonon interaction.展开更多
Self assembled quantum dots have shown a great promise as a leading candidate for infrared detection at room temperature. In this paper, a theoretical model of the absorption coefficient of quantum dot devices is pres...Self assembled quantum dots have shown a great promise as a leading candidate for infrared detection at room temperature. In this paper, a theoretical model of the absorption coefficient of quantum dot devices is presented. Both of bound to bound absorption and bound to continuum absorption are taken into consideration in this model. This model is based on the effective mass theory and the Non Equilibrium Greens Function (NEGF) formalism. NEGF formalism is used to calculate the bound to continuum absorption coefficient. The results of the model have been compared with a published experimental work and a good agreement is obtained. Based on the presented model, the bound to bound absorption coefficient component is compared to the bound to continuum absorption coefficient component. In addition, the effects of the dot dimensions and electron filling on the bound to continuum absorption coefficient are also investigated. In general, increasing the dot filling increases the absorption and decreasing the dots dimensions will increase the absorption and move the absorption peak towards longer wavelengths.展开更多
文摘Purpose: To study the clinicopathological change on "Multiple Evanescent White-dot Syndrome (MEWDS)"through fundus angiogrphy analyses.Methods:Examing the case with fluorescein angiography (FFA) and indocyanine green angiography(ICGA), visual field and following up for 15 months.Results :There exist multiple white dots in the fundus photo and angiography. The changes on ICGA maintain longer than fundus photo and FFA. Papille may be edematous and macula could present with special hypofluorescent flecks.Conclusions:MEWDS has specific angiographic features. Its pathological changes involve deep retinal pigment epithelium(RPE) as well as choroidal capillaries. The prognosis of the visual acuity for MEWDS is very good.
文摘Dot,line,plane,body are dominant elements for creating visual originality of modern landscapes,among which dot is the fundamental one in the visual design.It is a significant subject in modern landscape design to create visual originality and style of dotted landscapes,and also a premise for humanistic design.The visual characteristics of dotted landscapes were analyzed from the perspectives of style,size,location,configuration and so on.The principles of creating green visual originality for dotted landscapes were concluded,that is,coordination and unification,ratio and scale,balance and stability,rhythm and tempo.Then novel and elegant dotted landscapes can be created by using new materials and techniques,applying deformation,cutting and connection,alternation,distortion and rotation;by adopting motif composition method,motif with outstanding features can be selected as dotted landscapes to form contrast with background and break the rigid atmosphere.
文摘We have studied the transport properties of a ring-coupled quantum dot array driven by an AC magnetic field, which is connected to two leads, and we give the response of the transport current to the dynamical localization. We found that when the ratio of the magnetic flux to the total quantum dots number is a root of the zeroth order Bessel function, dynamical localization and collapse of quasi-energy occurs and importantly~ the transport current displays a dip which is the signal of dynamical localization. The dynamical localization effect is strengthened as a result of the increase of the quantum dot number, and it is weakened on account of the increase of the dots-lead hopping rate.
基金Project supported by the National Natural Science Foundation of China (Grant No 10574042) and the Guizhou Provincial Science and Technology Foundation of China (Grant No 20052088).
文摘This paper investigates theoretically the electronic structure and transport of a two-level quantum dot irradiated under a strong laser field at low temperatures. Using the method of Keldysh equation of motion for nonequilibrium Green functions, it examines the time-averaged density of states and conductance for the system with photon polarization parallel with and perpendicular to the tunnelling current direction respectively. It is demonstrated that, by analysing some numerical examples, more photon sidebands resonance states and multi-and single-photon transitions are found when diagonal matrix elements dominate the interaction, while the electronic transitions due to multiphoton absorption are more or less suppressed when off-diagonal interaction dominates.
基金supported by the Youth Foundation of Heilongjiang Province,China(Grant No.QC2009C41)the Heilongjiang Provincial Natural Science Foundation,China(Grant No.F200939)
文摘Using the nonequilibrium Keldysh Green's function technique, the Fano effect of a parallel-coupled triple Rashba quantum dot system is investigated. The conductance as a function of electron energy is numerically calculated. Compared with the case of a parallel-coupled double quantum dot system, two additional Fano resonance peaks occur in the conductance spectrum. By adjusting the structural parameters, the two Fano resonance peaks may change into the resoaance peaks. In addition, the influence of Rashba spin-orbit interaction on the conductance is studied.
基金Project supported by the Youth Foundation of Heilongjiang Province,China (Grant No. QC2009C41)the Heilongjiang Provincial Natural Science Foundation,China (Grant No. F200939)
文摘Using the nonequilibrium Green's function technique,electron transport through a laterally coupled vertical triple quantum dot is investigated.The conductance as a function of electron energy is numerically calculated.The evolution of the conductance strongly depends on the configuration of dot levels and interdot coupling strengths.
文摘Using Keldysh nonequilibrium Green function formalism and mapping a many-body electron-phonon interaction onto a one body problem, the electron transport through a serially coupled double quantum dot system is analyzed. The influence of the electron-phonon interaction, temperature, detuning, and interdot tunneling on the transmission coefficient and current is studied. Our results show that the electron-phonon interaction results in the appearance of the side peaks in the transmission coefficient, whose height is strongly dependent on the phonon temperature. We have also found that the inequality of the electron-phonon interaction strength in two dots gives rise to an asymmetry in the current-voltage characteristic. In addition, the temperature difference between the phonon and electron subsystems results in the reduction of the saturated current and the destruction of the step-like behavior of the current. It is also observed that the detuning can improve the magnitude of the current by compensating the mismatch of the quantum dots energy levels induced by the electron-phonon interaction.
文摘Self assembled quantum dots have shown a great promise as a leading candidate for infrared detection at room temperature. In this paper, a theoretical model of the absorption coefficient of quantum dot devices is presented. Both of bound to bound absorption and bound to continuum absorption are taken into consideration in this model. This model is based on the effective mass theory and the Non Equilibrium Greens Function (NEGF) formalism. NEGF formalism is used to calculate the bound to continuum absorption coefficient. The results of the model have been compared with a published experimental work and a good agreement is obtained. Based on the presented model, the bound to bound absorption coefficient component is compared to the bound to continuum absorption coefficient component. In addition, the effects of the dot dimensions and electron filling on the bound to continuum absorption coefficient are also investigated. In general, increasing the dot filling increases the absorption and decreasing the dots dimensions will increase the absorption and move the absorption peak towards longer wavelengths.