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Two-frequency mutual coherence function and its applications to pulse scattering by random rough surface

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Science China(Physics,Mechanics & Astronomy) 2008年第2期51卷 157-164页

作者： REN YuChao GUO LiXin School of Science Xidian UniversityXi’an 710071China

An analytic expression of the two-frequency mutual coherence function (MCF) was derived for a two-dimensional random rough surface. The scattered field was cal-culated by the Kirchhoff approximation, which is valid in the case that the radius of curvature of the surface is much larger than the incident wave length. The scatter-ing problem of narrowband pulse was investigated to simplify the analytic expres-sion of the two-frequency MCF. Numerical simulations show that the two-frequency MCF is greatly dependent on the root-mean-square (RMS) height, while less de-pendent on the correlation length. The analytic solutions were compared with the results of Monte Carlo simulation to assess the accuracy and computational efficiency.

关键词： mutual coherence function pulse scattering random rough surface

Macular retinal thickness and flow density change by optical coherence tomography angiography after posterior scleral reinforcement

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Science China(Life Sciences) 2019年第7期62卷 930-936页

作者： Liya Qiao Xifang Zhang Catherine Jan Xiaoxia Li Meng Li Huaizhou Wang Beijing Tongren Eye Center Beijing Tongren HospitalCapital Medical UniversityBeijing Institute of OphthalmologyBeijing Ophthalmology and Visual Sciences Key LaboratoryBeijing 100730China Centre for Brain and Cognitive Sciences and School of Psychological and Cognitive Sciences Peking UniversityBeijing 100871China

Optical coherence tomography angiography(Angio-OCT) has introduced a new non-invasive,quantitative method to assess superficial and deep capillary networks of the *** this study,we investigated macular retinal thickness and flow density change following posterior scleral reinforcement(PSR) surgery,using an RTVue XR Avanti Angio-OCT,in patients with pathological myopia.A total of 13 patients with pathological myopia were recruited and all patients completed the 6 months follow-up *** from 22 eyes were used in this *** mean age was 36.23±15.29 years,and 43%(n=6) were *** equivalent refractive error(SE) ranged from –8.0 to –24.0 *** axial length,best-corrected visual acuity and SE did not change significantly at each follow-up,compared with pre-operative measures(P>0.05).Postoperative flow density of superficial and deep retinal layers at each sector did not change significantly at each follow-up,compared with preoperative measures(P>0.05).However,we found significant decrease in retinal thickness of parafovea-inferior sector after PSR surgery(P<0.01),indicating potential relaxation of vitreofoveal traction after PSR surgery.

关键词： macular retinal thickness macular flow density optical coherence tomography angiography posterior scleral reinforcement

Uncertainty relations for quantum coherence with respect to mutually unbiased bases

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Frontiers of physics 2018年第1期13卷 179-185页

作者： Alexey E. Rastegin Department of Theoretical Physics Irkutsk State University Russia

The concept of quantum coherence, including various ways to quantify the degree of coherence with respect to the prescribed basis, is currently the subject of active research. The complementarity of quantum coherence in different bases was studied by deriving upper bounds on the sum of the corre- sponding measures. To obtain a two-sided estimate, lower bounds on the coherence quantifiers are also of interest. Such bounds are naturally referred to as uncertainty relations for quantum coherence. We obtain new uncertainty relations for coherence quantifiers averaged with respect to a set of mutually unbiased bases （MUBs）. To quantify the degree of coherence, the relative entropy of coherence and the geometric coherence are used. Further, we also derive novel state-independent uncertainty relations for a set of MUBs in terms of the min-entropy.

关键词： coherence complementarity uncertainty mutually unbiased bases

Uncertainty Relations for coherence

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Communications in Theoretical Physics 2019年第12期71卷 1443-1447页

作者：骆顺龙孙源 Academy of Mathematics and Systems Science Chinese Academy of SciencesBeijing 100190China School of Mathematical Sciences University of the Chinese Academy of SciencesBeijing 100049China

Quantum mechanical uncertainty relations are fundamental consequences of the incompatible nature of noncommuting *** terms of the coherence measure based on the Wigner-Yanase skew information,we establish several uncertainty relations for coherence with respect to von Neumann measurements,mutually unbiased bases(MUBs),and general symmetric informationally complete positive operator valued measurements(SIC-POVMs),*** coherence is intimately connected with quantum uncertainties,the obtained uncertainty relations are of intrinsically quantum nature,in contrast to the conventional uncertainty relations expressed in terms of variance,which are of hybrid nature(mixing both classical and quantum uncertainties).From a dual viewpoint,we also derive some uncertainty relations for coherence of quantum states with respect to a fixed *** particular,it is shown that if the density operators representing the quantum states do not commute,then there is no measurement(reference basis)such that the coherence of these states can be simultaneously small.

关键词： uncertainty relations coherence Wigner-Yanase skew information quantum uncertainty von Neumann measurements

Experimental observation of backscattered light based on different coherence between incident laser beams

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High Power Laser Science and Engineering 2013年第2期1卷 94-97页

作者： Xiangfu Meng Chen Wang Honghai An Guo Jia Huazhen Zhou Sizu Fu Shanghai Institute of Laser Plasma

Recent experimental results on NIF revealed a much higher stimulated Brillouin scattering(SBS)and stimulated Raman scattering(SRS)backscatter than expected;one possible reason was due to the coherence between incident laser *** our research,two laser beams(~1 ns,~250 J,527 nm in each one)with different coherent degrees between them from the SG-II facility were employed to irradiate an Au plate target;the backscatter of SBS and SRS in the range of the given solid angle had been *** results showed that it could change dramatically corresponding to the difference of the coherent degree between the two laser beams,and there was usually more intense backscatter the higher the coherent degree between the incident beams.

关键词： backscatter coherence laser–plasma interaction

Delay-induced coherence bi-resonance-like behavior in stochastic Hodgkin-Huxley neuron networks

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Science China Chemistry 2010年第8期53卷 1762-1766页

作者： HAO YingHang,GONG YuBing,LIN Xiu & MA XiaoGuang School of Physics,Ludong University,Yantai 264025,China School of Physics Ludong University Yantai China

In this paper,we study how information transmission delays affect the spiking behavior of electrically coupled stochastic Hodgkin-Huxley (HH) neurons on Newman-Watts *** is found that the spiking behavior becomes the most regular at an optimal time delay,indicating the occurrence of delay-induced coherence resonance-like (CR-like) ***,there are different CR-like types,depending on the membrane patch size of the *** a smaller patch size,only single CR-like behavior occurs;while for a larger patch size,coherence bi-resonance-like (CBR) behavior *** findings show that the delay-induced CR-like behavior is closely related to the channel noise strength,and the coupled neurons may exhibit different spiking behaviors under the interplay of the channel noise and time ***,the channel noise should be taken into account in the study of time delay-related spiking activity in stochastic HH *** work provides new insight into the role of channel noise and information transmission delays in realistic neural systems.

关键词： stochastic HH neuron delay through electric synapse coherence resonance and bi-resonance Newman-Watts network

Effects of chronic elevated intraocular pressure on parameters of optical coherence tomography in rhesus monkeys

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International Journal of Ophthalmology(English edition) 2019年第4期12卷 542-548页

作者： Zhi-Chao Yan Xue-Jiao Yang Hong-Rui Chen Shui-Feng Deng Ying-Ting Zhu Ye-Hong Zhuo Department of Ophthalmology the Second Affiliated Hospital of Guangzhou Medical University State Key Laboratory of Ophthalmology Zhongshan Ophthalmic Center Sun Yat-sen University Department of Ophthalmology the Affiliated Hospital of Qingdao University

AIM: To determine the progression of parameters from optical coherence tomography(OCT) in chronic elevated intraocular pressure(IOP) ***: A chronic elevated IOP model of rhesus monkeys was induced by laser photocoagulation. Representative OCT parameters, including the average and four-quadrant retinal nerve fiber layer(RNFL) thickness, and parameters from optic nerve head(ONH) analysis were collected before and after laser treatments biweekly for up to 28 wk. The performance of each parameter for early progression detection was analyzed. The progressive trends toward elevated IOP were analyzed using a linear mixed-effects ***: There were 10 successfully maintained high IOP eyes in 7 monkeys. The follow-up time was 24±5.37 wk. With cumulative IOP elevation, the cup area, rim area and C/D area ratio were statistically significantly changed as early as 2 wk after elevated IOP induction(P<0.05). The quadrant RNFL thickness changed at 6wk after high IOP induction, and the superior and inferior RNFL thicknesses exhibited more obvious reductions than other quadrants. The average RNFL thickness was the last one to show a significant decrease at ***: The parameters of ONH are most sensitive to elevated IOP in a primate glaucomatous model. These findings suggest that we should focus on those parameters instead of RNFL thickness in patients with elevated IOP, as they might present with earlier glaucomatous changes.

关键词： optical coherence tomography rhesus monkey glaucoma high intraocular pressure retinal nerve fiber layer

Segmentation of retinal fluid based on deep learning:application of three-dimensional fully convolutional neural networks in optical coherence tomography images

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International Journal of Ophthalmology(English edition) 2019年第6期12卷 1012-1020页

作者： Meng-Xiao Li Su-Qin Yu Wei Zhang Hao Zhou Xun Xu Tian-Wei Qian Yong-Jing Wan School of Information Science and Engineering East China University of Science and TechnologyShanghai 200237China Department of Ophthalmology Shanghai General HospitalShanghai Jiaotong University School of MedicineShanghai Key Laboratory of Ocular Fundus DiseasesShanghai 200080China

AIM: To explore a segmentation algorithm based on deep learning to achieve accurate diagnosis and treatment of patients with retinal ***: A two-dimensional(2D) fully convolutional network for retinal segmentation was employed. In order to solve the category imbalance in retinal optical coherence tomography(OCT) images, the network parameters and loss function based on the 2D fully convolutional network were modified. For this network, the correlations of corresponding positions among adjacent images in space are ignored. Thus, we proposed a three-dimensional(3D) fully convolutional network for segmentation in the retinal OCT ***: The algorithm was evaluated according to segmentation accuracy, Kappa coefficient, and F1 score. For the 3D fully convolutional network proposed in this paper, the overall segmentation accuracy rate is 99.56%, Kappa coefficient is 98.47%, and F1 score of retinal fluid is 95.50%. CONCLUSION: The OCT image segmentation algorithm based on deep learning is primarily founded on the 2D convolutional network. The 3D network architecture proposed in this paper reduces the influence of category imbalance, realizes end-to-end segmentation of volume images, and achieves optimal segmentation results. The segmentation maps are practically the same as the manual annotations of doctors, and can provide doctors with more accurate diagnostic data.

关键词： optical coherence tomography images fluid segmentation 2D fully convolutional network 3D fully convolutional network

Microvascular changes after conbercept therapy in central retinal vein occlusion analyzed by optical coherence tomography angiography

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International Journal of Ophthalmology(English edition) 2019年第5期12卷 802-808页

作者： Yang Deng Qi-Wen Zhong Ai-Qi Zhang Xiao-Juan Cai Ming-Zhi Lu Shao-Chong Zhang Li-Shi Su Hui Chen Ying Lin Li-Mei Sun Guan-Di Chen Li-Ting Zhong Chen-Jin Jin Wei Chi State Key Laboratory of Ophthalmology Zhongshan Ophthalmic CenterSun Yat-sen University Wuping Hospital The Second Affiliated Hospital of Harbin Medical University The People's Hospital of Gaoyao District

AIM: To investigate microvascular changes in eyes with central retinal vein occlusion(CRVO) complicated by macular edema before and after intravitreal conbercept injection and evaluate correlations between these changes and best-corrected visual acuity(BCVA) and retinal thickness. METHODS: Twenty-eight eyes of 28 patients with macular edema caused by CRVO were included in this retrospective study. All patients received a single intravitreal conbercept injection to treat macular edema. BCVA and the results of optical coherence tomography angiography(OCTA) automatic measurements of the vessel density in the superficial(SCP) and deep retinal capillary plexus(DCP), the foveal avascular zone(FAZ) area, the FAZ perimeter(PERIM), the vessel density within a 300-μm wide ring surrounding the FAZ(FD-300), the acircularity index(AI), the choriocapillaris flow area, and retinal thickness were recorded before and at one month after treatment and compared with the results observed in age-and sexmatched healthy subjects. RESULTS: The vessel density in the SCP and DCP, the FD-300, and the flow area of the choriocapillaris were allsignificantly lower in CRVO eyes than in healthy eyes, while the AI and retinal thickness were significantly higher(all P<0.05). After treatment, retinal thickness was significantly decreased, and the mean BCVA had markedly improved from 20/167 to 20/65(P=0.0092). The flow area of the choriocapillaris was also significantly improved, which may result from the reduction of shadowing effect caused by the attenuation of macular edema. However, there were no significant changes in SCP and DCP vessel density after treatment. The flow area of the choriocapillaris at baseline was negatively correlated with retinal ***: OCTA enables the non-invasive, layerspecific and quantitative assessment of microvascular changes both before and after treatment, and can therefore be used as a valuable imaging tool for the evaluation of the follow-up in CRVO pat

关键词： central retinal vein occlusion optical coherence tomography angiography macular edema conbercept vessel density flow area foveal avascular zone