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symmetry of upper eyelid after unilateral blepharoptosis repair with minimally invasive conjoint fascial sheath suspension technique

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International Journal of Ophthalmology(English edition) 2024年第1期17卷 53-60页

作者： Yianzhu Liu Wenli Chen Xia Chen Tianjin Eye Hospital Tianjin 300020China Tianjin Key Lab of Ophthalmology and Visual Science Tianjin 300020China

AIM:To investigate the symmetry of upper eyelid in patients with unilateral mild and moderate blepharoptosis who underwent unilateral minimally invasive combined fascia sheath(CFS)***:A retrospective study of patients who underwent unilateral minimally invasive CFS suspension surgery between January 2018 and December *** criteria included unilateral mild and moderate ptosis,good levator muscle function(>9 mm)and follow-up of at least ***-and post-operative symmetry was graded subjectively for marginal reflex distance 1(MRD1),tarsal platform show(TPS)and eyebrow fat span(BFS).A t-test was used to evaluate MRD1,TPS and BFS asymmetry by calculating delta *** Bézier curve tool of the Image J software was used to extract the upper eyelid contours,where the symmetry was measured by the percentage of overlapping curvatures(POC).RESULTS:Totally 105 patients(105 eyelids)were included(mild group,n=84;moderate group,n=21).Postoperatively,all patients increased MRD1 and decreased TPS in the ptotic eye while maintaining unchanged *** asymmetric delta value for MRD1 was measured to be 1.48±0.86 preoperatively,and it decreased to 0.58±0.67 postoperatively in all cases(P=0.0004).In patients with mild ptosis,the asymmetry value of TPS fell significantly from 1.15±0.62 to 0.68±0.38(P=0.0187).The symmetry of the upper eyelid contour increased in all subgroups of patients,with a POC of 59.39%±13.45%preoperatively and POC of 78.29%±13.80%***:Minimally invasive CFS suspension is proved to be an effective means of improving the symmetry of unilateral ptosis in terms of MRD1(all subgroups),POC(all subgroups)and TPS(only mild group),whereas BFS is unaffected.

关键词： symmetry unilateral blepharoptosis minimally invasive combined fascia sheath suspension

Multi-layer analytic solution for k-ωmodel equations via a symmetry approach

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Applied Mathematics and Mechanics(English Edition) 2023年第2期44卷 289-306页

作者： Fan TANG Weitao BI Zhensu SHE Department of Mechanics and Engineering Science College of EngineeringPeking UniversityBeijing 100871China State Key Laboratory for Turbulence and Complex Systems Peking UniversityBeijing 100871China

Despite being one of the oldest and most widely-used turbulence models in engineering computational fluid dynamics(CFD),the k-ωmodel has not been fully understood theoretically because of its high nonlinearity and complex model parameter ***,a multi-layer analytic expression is postulated for two lengths(stress and kinetic energy lengths),yielding an analytic solution for the k-ωmodel equations in pipe *** local balance equations are analyzed to determine the key parameters in the solution,which are shown to be rather close to the empirically-measured values from the numerical solution of the Wilcox k-ωmodel,and hence the analytic construction is fully *** results provide clear evidence that the k-ωmodel sets in it a multilayer structure,which is similar to but different,in some insignificant details,from the Navier-Stokes(N-S)*** finding explains why the k-ωmodel is so popular,especially in computing the near-wall ***,the analysis is extended to a newlyrefined k-ωmodel called the structural ensemble dynamics(SED)k-ωmodel,showing that the SED k-ωmodel has improved the multi-layer structure in the outer flow but preserved the setting of the k-ωmodel in the inner region.

关键词： turbulence model k-ωmodel structural ensemble dynamics(SED) multilayer structure symmetry

Unfolding the structural stability of nanoalloys via symmetry-constrained genetic algorithm and neural network potential

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npj Computational Materials 2022年第1期8卷 1135-1145页

作者： Shuang Han Giovanni Barcaro Alessandro Fortunelli Steen Lysgaard Tejs Vegge Heine Anton Hansen Department of Energy Conversion and Storage Technical University of DenmarkFysikvej2800Kgs.LyngbyDenmark CNR-ICCOM&IPCF Consiglio Nazionale delle Ricerchevia G.Moruzzi 156124PisaItaly

The structural stability of nanoalloys is a challenging research subject due to the complexity of size,shape,composition,and chemical *** genetic algorithm is a popular global optimization method that can efficiently search for the ground-state nanoalloy ***,the algorithm suffers from three significant limitations:the efficiency and accuracy of the energy evaluator and the algorithm’s *** we describe the construction of a neural network potential intended for rapid and accurate energy predictions of Pt-Ni nanoalloys of various sizes,shapes,and *** further introduce a symmetry-constrained genetic algorithm that significantly improves the efficiency and viability of the algorithm for realistic size *** combination of the two allows us to explore the space of homotops and compositions of Pt-Ni nanoalloys consisting of up to 4033 atoms and quantitatively report the interplay of shape,size,and composition on the dominant chemical ordering patterns.

关键词： structure symmetry constrained

Observation of parity-time symmetry in time-division multiplexing pulsed optoelectronic oscillators within a single resonator

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Photonics Research 2022年第8期10卷 1915-1923页

作者： HAO DING QIZHUANG CEN KUN XU MING LI YITANG DAI State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and TelecommunicationsBeijing 100876China State Key Laboratory on Integrated Optoelectronics Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China School of Electronic Electrical and Communication EngineeringUniversity of Chinese Academy of SciencesBeijing 100049China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100190China Peng Cheng Laboratory Shenzhen 518052China

In recent years,parity-time(PT)symmetry in optoelectronic systems has been widely studied,due to its potential applications in lasers,sensors,topological networks,and other *** this paper,a time-division multiplexed pulsed optoelectronic oscillator(OEO)is proposed to study the dynamics of a PT symmetry *** microwave pulses are used to realize the PT symmetry in a single spatial resonator based on the temporal degrees of *** gain and loss of the microwave pulses and the coupling coefficient between them can then be *** first demonstrate the phase diagram from PT broken to PT symmetry in the OEO *** theoretically prove that the perturbation of a coupling-induced phase shift larger than(2π)×10^(-2)causes the disappearance of the PT *** this experiment,the perturbation is less than(2π)×0.5×10^(-2);thus,the phase transition of PT symmetry is *** addition,multipairs of PT-symmetry pulses indicate that pulsed OEO could be used to implement complex non-Hermitian Hamilton ***,it is confirmed that pulsed OEO is an excellent platform to explore the dynamics of PT symmetry and other non-Hermitian Hamiltonian systems.

关键词： optoelectronic resonator symmetry

Anisotropic Dzyaloshinskii-Moriya interaction protected by D_(2d) crystal symmetry in two-dimensional ternary compounds

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npj Computational Materials 2022年第1期8卷 1209-1215页

作者： Yonglong Ga Qirui Cui Yingmei Zhu Dongxing Yu Liming Wang Jinghua Liang Hongxin Yang Ningbo Institute of Materials Technology and Engineering Chinese Academy of SciencesNingbo315201China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing100049China

Magnetic skyrmions,topologically protected chiral spin swirling quasiparticles,have attracted great attention in fundamental physics and ***,the discovery of two-dimensional(2D)van der Waals(vdW)magnets have aroused great interest due to their appealing physical ***,both experimental and theoretical works have revealed that isotropic Dzyaloshinskii–Moriya interaction(DMI)can be achieved in 2D magnets or ferromagnet-based ***,2D magnets with anisotropic DMI haven’t been reported ***,via using first-principles calculations,we unveil that anisotropic DMI protected by D_(2d)crystal symmetry can exist in 2D ternary compounds MCuX_(2)(M:3d transition metal(TM),X:group VIA).Interestingly,by using micromagnetic simulations,we demonstrate that ferromagnetic(FM)antiskyrmions,FM bimerons,antiferromagnetic(AFM)antiskyrmions,and AFM bimerons can be realized in the MCuX_(2)*** discovery opens up an avenue to creating antiskyrmions and bimerons with anisotropic DMI protected by D_(2d)crystal symmetry in 2D magnets.

关键词： DMI symmetry magnets

symmetry-protected third-order exceptional points in staggered flatband rhombic lattices

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Photonics Research 2023年第2期11卷 225-233页

作者： YINGYING ZHANG SHIQIANG XIA XINGDONG ZHAO LU QIN XUEJING FENG WENRONG QI YAJING JIANG HAI LU DAOHONG SONG LIQIN TANG ZUNLUE ZHU WUMING LIU YUFANG LIU School of Physics Henan Normal UniversityXinxiang 453007China MOE Key Laboratory of Weak-Light Nonlinear Photonics TEDA Applied Physics Institute and School of PhysicsNankai UniversityTianjin 300457China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China Institute of Physics Henan Academy of SciencesZhengzhou 450046China

Higher-order exceptional points(EPs), which appear as multifold degeneracies in the spectra of non-Hermitian systems, are garnering extensive attention in various multidisciplinary fields. However, constructing higher-order EPs still remains a challenge due to the strict requirement of the system symmetries. Here we demonstrate that higher-order EPs can be judiciously fabricated in parity–time(PT)-symmetric staggered rhombic lattices by introducing not only on-site gain/loss but also non-Hermitian couplings. Zero-energy flatbands persist and symmetry-protected third-order EPs(EP3s) arise in these systems owing to the non-Hermitian chiral/sublattice symmetry, but distinct phase transitions and propagation dynamics occur. Specifically, the EP3 arises at the Brillouin zone(BZ) boundary in the presence of on-site gain/loss. The single-site excitations display an exponential power increase in the PT-broken phase. Meanwhile, a nearly flatband sustains when a small lattice perturbation is applied. For the lattices with non-Hermitian couplings, however, the EP3 appears at the BZ center. Quite remarkably, our analysis unveils a dynamical delocalization-localization transition for the excitation of the dispersive bands and a quartic power increase beyond the EP3. Our scheme provides a new platform toward the investigation of the higher-order EPs and can be further extended to the study of topological phase transitions or nonlinear processes associated with higher-order EPs.

关键词： exceptional protected symmetry

Anti-parity-time symmetry enabled on-chip chiral polarizer

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Photonics Research 2022年第1期10卷 76-83页

作者： YANXIAN WEI HAILONG ZHOU YUNTIAN CHEN YUNHONG DING JIANJI DONG XINLIANG ZHANG Wuhan National Laboratory for Optoelectronics School of Optical and Electronic InformationHuazhong University of Science and TechnologyWuhan 430074China Department of Photonics Engineering Technical University of Denmark2800 LyngbyDenmark SiPhotonIC ApS 2830 VirumDenmark

Encircling an exceptional point(EP) in a parity-time(PT) symmetric system has shown great potential for chiral optical devices,such as chiral mode switching for symmetric and antisymmetric ***,to our best knowledge,chiral switching for polarization states has never been reported,although chiral polarization manipulation has significant applications in imaging,sensing,communication,***,inspired by the anti-PT symmetry,we demonstrate,for the first time to our best knowledge,an on-chip chiral polarizer by constructing a polarization-coupled anti-PT symmetric *** transmission axes of the chiral polarizer are different for forward and backward propagation.A polarization extinction ratio of over 10 dB is achieved for both propagating ***,a telecommunication experiment is performed to demonstrate the potential applications in polarization encoding *** provides a novel functionality for encircling-an-EP parametric evolution and offers a new approach for on-chip chiral polarization manipulation.

关键词： chiral symmetry parity

Tunable parity-time symmetry vortex laser from a phase change material-based microcavity

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Microsystems & Nanoengineering 2023年第6期9卷 273-280页

作者： Ying Su Hongji Fan Shitong Zhang Tun Cao School of Optoelectronic Engineering and Instrumentation Science Dalian University of TechnologyDalian 116024China School of Science and Letters UC Davis21005th StDavisCA 95618USA

Traditional light sources cannot emit an electromagnetic(EM)field with an orbital angular momentum(OAM),limiting their applications in modern *** recent development of the OAM laser,mainly based on micro-and nanostructures,can satisfy the increasing requirements for on-chip photonics and information ***,the photonic structures have fixed parameters that prevent these OAM lasers from being dynamically ***,we propose tunable vortex lasing from a microring cavity integrated by a phase change material,Ge_(2)Sb_(2)Te_(5)(GST225).By modulating the complex refractive index to create an exceptional point(EP)to break the degeneracy of whispering gallery modes with opposite orientations,the microlaser working at the EP can impart an artificial angular momentum,thus emitting vortex beams with well-defined *** grating scatter on the edge of the microring can provide efficient vertical *** vortex laser wavelength from the GST225/InGaAsP dual-layered microring cavity can be dynamically tuned by switching the state of GST225 between amorphous and crystalline without changing the microring *** construct an electric-thermal model to show the tuning range of operating wavelengths(EPs)from 1544.5 to 1565.9 nm in~25 *** study on high-speed tunable PT-symmetry vortex lasers facilitates the next generation of integrated optoelectronic devices for optical computing and communications in both classical and quantum regions.

关键词： tuning symmetry vortex

Steerable merging bound states in the continuum on a quasi-flatband of photonic crystal slabs without breaking symmetry

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光子学研究:英文版 2023年第7期11卷 1262-1274页

作者： XIN QI JIAJU WU FENG WU MINA REN QIAN WEI YUFEI WANG HAITAO JIANG YUNHUI LI ZHIWEI GUO YAPING YANG WANHUA ZHENG YONG SUN HONG CHEN MOE Key Laboratory of Advanced Micro-structured Materials School of Physics Sciences and EngineeringTongji UniversityShanghai 200092China School of Optoelectronic Engineering Guangdong Polytechnic Normal UniversityGuangzhou 510665China State Key Laboratory on Integrated Optoelectronics Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China Department of Electrical Engineering Tongji UniversityShanghai 201804China

Optical resonators with high quality(Q)factors are paramount for the enhancement of light–matter interactions in engineered photonic structures,but their performance always suffers from the scattering loss caused by fabrication *** bound states in the continuum(BICs)provide us with a nontrivial physical mechanism to overcome this challenge,as they can significantly improve the Q factors of ***,most of the reported merging BICs are found atΓpoint(the center of the Brillouin zone),which intensively limits many potential applications based on angular *** date,studies on manipulating merging BICs at off-Γpoint are always accompanied by the breaking of structural symmetry that inevitably increases process difficulty and structural defects to a certain ***,we propose a scheme to construct merging BICs at almost an arbitrary point in momentum space without breaking *** by the topological features of BICs,we merge four accidental BICs with one symmetry-protected BIC at theΓpoint and merge two accidental BICs with opposite topological charges at the off-Γpoint only by changing the periodic constant of a photonic crystal ***,the position of off-Γmerging BICs can be flexibly tuned by the periodic constant and height of the structure ***,it is observed that the movement of BICs occurs in a quasi-flatband with ultra-narrow ***,merging BICs in a tiny band provide a mechanism to realize more robust ultrahigh-Q resonances that further improve the optical performance,which is limited by wide-angle ***,as an example of application,effective angle-insensitive second-harmonic generation assisted by different quasi-BICs is numerically *** findings demonstrate momentum-steerable merging BICs in a quasi-flatband,which may expand the application of BICs to the enhancement of frequency-sensitive light–matter interaction with angular selectivit

关键词： quasi symmetry breaking