Accuracy of axial length measurements from immersion B-scan ultrasonography in highly myopic eyes

AIM:To evaluate the accuracy of axial length(AL)measurements obtained from immersion B-scan ultrasonography(immersion B-scan)for intraocular lens(IOL)power calculation in patients with high myopia and cataracts.METHODS:Immersion B-scan,contact A-scan ultrasonography(contact A-scan),and the IOLMaster were used to preoperatively measure the AL in 102 eyes from 102 patients who underwent phacoemulsification and IOL implantation.Patients were divided into two groups according to the AL:one containing patients with22 mm≤AL【26 mm(group A)and the other containing patients with AL≥26 mm(group B).The mean error(ME)was calculated from the difference between the AL measurement methods predicted refractive error and the actual postoperative refractive error.RESULTS:Ingroup A,ALs measured byimmersion Bscan(23.48±1.15)didn’t differ significantly from those measured by the IOLMaster(23.52±1.17)or from those by contact A-scan(23.38±1.20).In the same group,the standard deviation(SD)of the mean error(ME)of immersion B-scan(-0.090±0.397 D)didn’t differ significantly from those of IOLMaster(-0.095±0.411 D)and contact A-scan(-0.099±0.425 D).In group B,ALs measured by immersion B-scan(27.97±2.21 mm)didn’t differ significantly from those of the IOLMaster(27.86±2.18 mm),but longer than those measured by Contact A-scan(27.75±2.23 mm,P=0.009).In the same group,the standard deviation(SD)of the mean error(ME)of immersion B-scan(-0.635±0.157 D)didn’t differ significantly from those of the IOLMaster(-0.679±0.359 D),but differed significantly from those of contact A-scan(-0.953±1.713 D,P=0.028).CONCLUSION:ImmersionB-scanexhibitsmeasurement accuracy comparable to that of the IOLMaster,and is thus a good alternative in measuring AL in eyes with high myopia when the IOLMaster can’t be used,and it is more accurate than the contact A-scan.

Comparison axial length measurements from three biometric instruments in high myopia

AIM： To compare the axial lengths （ALs） measured with Lenstar, IOLMaster and A-scan contact ultrasound （Ultrasound） in normal and high myopia （HM）. METHODS： Eighty-four normal eyes and 49 HM eyes were included. Three consecutive measurements were performed on each eye in the following order： Lenstar, IOLMaster, and Ultrasound. The repeatabilities of the AL measurements for each instrument were assessed by calculating the pooled coefficients of variation （CVs） of 18 eyes in each group. Comparisons between the HM and normal groups were made with independent sample t-tests. The inter-device agreements were evaluated with Bland-Altman analyses and paired two-tailed t-tests. RESULTS： For normal group, the CVs of the AL measurements taken with the Lenstar, IOLMaster and Ultrasound were 0.001%, 0.01% and 0.14%, respectively. The corresponding CVs for the HM group were 0.005%, 0.02% and 0.15%, respectively. There was significant difference between the Lenstar and the IOLMaster in normal group （P=0.031） but not in HM group （n=0.100）. In the two groups, the Lenstar and the IOLMaster produced higher values than did the Ultrasound （all P〈 0.001）. All three instruments exhibited good agreement in terms of AL values. For the intraocular lens （IOL） power calculation using SRK II formula, the Lenstar and the IOLMaster showed 0.5 D higher than Ultrasound in both groups （all P〈0.001）. No significant difference existed between the Lenstar and the IOLMaster for the IOL power calculation in both normal （n=0.474） and HM group （P= 0.103）. CONCLUSION： The three devices exhibited excellent intra-visit repeatabilities in the AL measurements. The AL and IOL power difference between partial coherence interferometry and ultrasound instruments should be noticed.

On the Elastic Vibration Model for High Length-Diameter Ratio Rocket with Attitude Control System

An elastic vibration model for high length diameter ratio spinning rocket with attitude control system which can be used for trajectory simulation is established. The basic theory of elastic dynamics and vibration dynamics were both used to set up the elastic vibration model of rocket body. In order to study the problem more conveniently, the rocket's body was simplified to be an even beam with two free ends. The model was validated by simulation results and the test data.

Accuracy of segmented measurement of axial length in ultra-high myopia filled with silicone oil using immersion B-scan ultrasonography

AIM:To evaluate the accuracy of segmented measurement of axial length(AL)in high myopia filled with silicone oil by immersion B-scan ultrasonography(immersion B-scan).METHODS:From June 2016 to June 2020,a total of 67 ultra-high myopia inpatients(67 eyes)who underwent silicone oil removal combined with cataract extraction and intraocular lens(IOL)implantation were retrospectively enrolled.The preoperative axial length(AL)of 31 patients with severe cataract were segmented measured using immersion B-scan(B-scan group)and another 36 patients with mild or moderate cataract were measured using IOLMaster 500(IOLMaster group).The post-operative ALs in two groups were both measured using IOLMaster 500.The IOL power was calculated with Haigis formula.The differences in ALs between pre-and post-surgery,as well as the postoperative refractive spherical equivalent,absolute refractive error,the prediction deviation of postoperative refraction and best corrected visual acuity(BCVA)were compared.RESULTS:The pre-and post-operative ALs were 30.46±1.63 mm(range 28.09-33.51 mm)and 30.42±1.70 mm(range 28.03-33.90 mm)in B-scan group(t=0.644,P=0.542)and 30.51±1.21 mm(range 28.03-33.90 mm)and 30.43±1.27 mm(range 28.54-33.50 mm)in IOLMaster group(t=1.843,P=0.074),respectively.Three months after surgery,BCVA were 0.45±0.13(range 0.3-0.9)and 0.44±0.20(range 0.2-1.0)in B-scan and IOLMaster group respectively(t=0.086,P=0.932).There was no significant difference of the postoperative spherical equivalent(-3.11±0.65 D vs-3.21±0.51 D,t=0.671,P=0.505)and the absolute refractive error(0.589±0.340 vs 0.470±0.245 D,t=1.615,P=0.112)between two groups.In B-scan group,absolute refractive error within±0.50 D was found in 18 eyes(58.1%),within±1.00 D in 26 eyes(83.9%),and within±1.50 D in 31 eyes(100%).In IOLMaster group,absolute refractive error within±0.50 D was found in 23 eyes(63.9%),within±1.00 D in 34 eyes(94.4%),and within±1.50 D in 36 eyes(Z=0.757,P=0.449).CONCLUSION:The segmented measurement of ALs by immersion B-scan shows comparable measurement accuracy with that of IOLMaster 500 in ultra-high myopia patients with severe cataract secondary to silicone oil filling and can obtain an ideal postoperative refractive state.

Change in foveal position based on age and axial length in high myopic eyes

AIM：To evaluate the influence of age and axial length（AL） on the position of the fovea in patients with high myopia（HM）.METHODS：In this prospective study,96 patients（186 eyes） with HM were consecutively recruited from the Third Affiliated Hospital of Nanchang University.DRI-OCT Atlantis,fundus imaging,and IOL Master were used in this study.Three indices were measured：the distance between the fovea and the optic nerve head（ONH） center（DFO）,the vertical distance between the fovea and the horizontal line pass of the ONH center（VDFO）,and the horizontal distance between the fovea and the vertical line pass of the ONH center（HDFO）.These measurements were used to analyze the effects of different age groups（A1,A2,A3 groups） and AL（AL1,AL2,AL3,AL4 groups） on these indices.RESULTS：The results showed that there was no statistical significance in DFO among the age and AL groups（F=0.46,0.37;P=0.62,0.76,respectively）.In HDFO,there was also no statistical significance among the age and AL groups（F=0.10,0.48;P=0.90,0.69,respectively）.In VDFO,however,the difference in the age and AL groups was statistically significant（F=3.21,3.12;P=0.04,0.02,respectively）.Thus,VDFO were correlated with age and AL（r=0.21,0.23,all P〈0.01）,while HDFO and DFO were not correlated with age and AL（r=0.30,P〉0.05）.CONCLUSION：In high myopia,the foveal position changes mainly in the vertical direction along with factors of age and AL.

Factors associated with axial length elongation in high myopia in adults

AIM:To investigate the association of axial length(AL)and ocular factors on AL elongation.METHODS:A retrospective chart review of patients who underwent two or more AL examinations for more than two years.Totally 4 groups were divided according to initial AL(<24 mm,24-26 mm,26-28 mm,≥28 mm).Initial fundus photograph was used to find risk factors associated AL elongation.RESULTS:The mean age of the patients was 47.21±7.79 y.AL remained almost unchanged in the groups with AL<24 mm and 24≤AL<26 mm.On the contrary,AL increased by 0.011 mm/y in the group with 26≤AL<28 mm and 0.035 mm/y in the group with AL≥28 mm(P<0.001).In high myopia,AL elongation increased in eye with longer AL(r=0.003,P=0.024),female gender(r=0.014,P=0.019),eye with larger peripapillary chorioretinal atrophic area(r=0.002,P=0.019),and smaller vascular arcade angle(r=-0.004,P=0.006).The risk of elongation 0.03 mm/y in high myopia was increased in female gender(P=0.040),and gradually increased in eye with large peripapillary chorioretinal atrophy area(P<0.01).CONCLUSION:AL elongate significantly in the eye with longer AL,female gender,and the eye with larger atrophic area and smaller arcade angle on fundus photography.

Flexural Bond Behavior of Rebar in Ultra-High Performance Concrete Beams Considering Lap-Splice Length and Cover Depth

This study intends to find out the correlation between the cover depth and the bond characteristics of UHPC through pull-out tests of UHPC specimens with different cover depths and bond tests of rebar using flexural members. In this experimental study, specimens are fabricated with the lap-splice length as test variable in relation with the calculation of the lap-splice length for 180- MPa UHPC. Moreover, specimens are also fabricated with the cover depth as test variable to evaluate the effect of the cover depth on the UHPC flexural members. The load-displacement curves are analyzed for each of these test variables to compute the lap-splice length proposed in the K-UHPC structural design guideline and to evaluate the influence of the cover depth on the flexural members. As a result, the stability of the structural behavior can be significantly enhanced by increasing slightly the cover depth specification of the current UHPC Structure Design Guideline from the maximum value between 1.5 times of rebar diameter and 20 mm to the maximum value between 1.5 times of rebar diameter and 25 mm.

Effect of gate length on breakdown voltage in AlGaN/GaN high-electron-mobility transistor

The effects of gate length L_G on breakdown voltage VBRare investigated in AlGaN/GaN high-electron-mobility transistors（HEMTs） with L_G= 1 μm^20 μm. With the increase of L_G, VBRis first increased, and then saturated at LG= 3 μm. For the HEMT with L_G= 1 μm, breakdown voltage VBRis 117 V, and it can be enhanced to 148 V for the HEMT with L-_G= 3 μm. The gate length of 3 μm can alleviate the buffer-leakage-induced impact ionization compared with the gate length of 1 μm, and the suppression of the impact ionization is the reason for improving the breakdown voltage.A similar suppression of the impact ionization exists in the HEMTs with LG〉 3 μm. As a result, there is no obvious difference in breakdown voltage among the HEMTs with LG= 3 μm^20 μm, and their breakdown voltages are in a range of 140 V–156 V.

Selection of optimal window length using STFT for quantitative SNR analysis of LFM signal

An adaptive approach to select analysis window param- eters for linear frequency modulated （LFM） signals is proposed to obtain the optimal 3 dB signal-to-noise ratio （SNR） in the short- time Fourier transform （STFT） domain. After analyzing the instan- taneous frequency and instantaneous bandwidth to deduce the relation between the window length and deviation of the Gaus- sian window, high-order statistics is used to select the appropriate window length for STFT and get the optimal SNR with the right time-frequency resolution according to the signal characteristic under a fixed sampling rate. Computer simulations have verified the effectiveness of the new method.

Study on the breakup lengths of free round liquid jets

An experi ment was conducted to measure the breakup lengths of water jets with a high-speed video camera for Weber numbers from0 to about 1.1×103.The initial jet diameters are changed from0.3 mmto 1. 0 mm.The results indicate that at lowjet velocity the breakup lengths of the jets are increased linearly from 0 to a maxi mumvalue.At the Weber number about 20 the breakup length of the jet reaches its maxi mum value for different initial jet diameter.Acomputation based onthe dispersion equationis conducted to study the relationship between the growth rate of the jet surface wave and the maxi mumbreakup length.The computations showthat the maxi mumgrowth rate for the axisymmetric surface wave has a turning point at Weber number about 20,and that agrees well with the experi ments.

A Genome‑Wide Association Study for Susceptibility to Axial Length in Highly Myopic Eyes

High myopia has long been highly prevalent worldwide with a largely yet unexplained genetic contribution.To identify novel susceptibility genes for axial length(AL)in highly myopic eyes,a genome-wide association study(GWAS)was performed using the genomic dataset of 350 deep whole-genome sequencing data from highly myopic patients.Top single nucleotide polymorphisms(SNPs)were functionally annotated.Immunofluorescence staining,quantitative polymerase chain reaction,and western blot were performed using neural retina of form-deprived myopic mice.Enrichment analyses were further performed.We identified the four top SNPs and found that ADAM Metallopeptidase With Thrombospondin Type 1 Motif 16(ADAMTS16)and Phosphatidylinositol Glycan Anchor Biosynthesis Class Z(PIGZ)had the potential of clinical signifi-cance.Animal experiments confirmed that PIGZ expression could be observed and showed higher expression level in form-deprived mice,especially in the ganglion cell layer.The messenger RNA(mRNA)levels of both ADAMTS16 and PIGZ were significantly higher in the neural retina of form-deprived eyes(p=0.005 and 0.007 respectively),and both proteins showed significantly upregulated expression in the neural retina of deprived eyes(p=0.004 and 0.042,respectively).Enrichment analysis revealed a significant role of cellular adhesion and signal transduction in AL,and also several AL-related pathways including circadian entrainment and inflammatory mediator regulation of transient receptor potential channels were proposed.In conclusion,the current study identified four novel SNPs associated with AL in highly myopic eyes and confirmed that the expression of ADAMTS16 and PIGZ was significantly upregulated in neural retina of deprived eyes.Enrichment analyses provided novel insight into the etiology of high myopia and opened avenues for future research interest.

Internal limiting membrane peeling combined with silicone oil or air tamponade for highly myopic foveoschisis

AIM:To compare the efficacy of pars plana vitrectomy(PPV)combined with internal limiting membrane(ILM)and silicone oil or sterile air tamponade for the treatment of myopic foveoschisis(MF)in highly myopic eyes.METHODS:This retrospective study included 48 myopic eyes of 40 patients with MF and axial lengths(ALs)ranging from 26-32 mm treated between January 2020 and January 2022.All patients were underwent PPV combined with ILM peeling followed by sterile air or silicone oil tamponade and followed up at least 12mo.Based on the features on spectral-domain optical coherence tomography(SD-OCT),the eyes were divided into the MF-only group(Group A,n=15 eyes),MF with central foveal detachment group(Group B,n=20 eyes),and MF with lamellar macular hole group(Group C,n=13 eyes).According to AL,eyes were further divided into three groups:Group D(26.01-28.00 mm,n=12 eyes),Group E(28.01-30.00 mm,n=26 eyes),and Group F(30.01-32.00 mm,n=10 eyes).The best-corrected visual acuity(BCVA),central foveal thickness(CFT),and complications were recorded.RESULTS:The patients included 16 males and 24 females with the mean age of 56±9.82y.The BCVA and CFT improved in all groups after surgery(P<0.01),while there was no significant difference of the CFT in Group A,B,and C postoperatively(P>0.05).The intergroup differences of BCVA and CFT postoperatively were statistically significant in Group D,E,and F.Twenty eyes were injected with sterile air,and 28 eyes were injected with silicone oil for tamponade based on the AL.However,there was no statistically significant difference among Groups D,E,and F in terms of the results of sterile air or silicone oil tamponade.The mean recovery time was 5.9mo for MF patients subjected to silicone oil tamponade and 7.7mo for patients subjected to sterile air tamponade,and the difference was not statistically significant.CONCLUSION:PPV and ILM peeling combined with silicone oil or sterile air tamponade can achieve good results for MF in highly myopic eyes with ALs≤32 mm.

Length estimation of extended targets based on bistatic high resolution range profile

The approach to estimate the length of extended targets by using the bistatic high resolution range profile（ H RRP） is analyzed in this paper. The relationship between the bistatic H RRP and the monostatic H RRP of extended targets are investigated. It is demonstrated by simulations that the target length measured by the bistatic H RRP is more meaningful and accurate than that by the monostatic HRRP,though the monostatic H RRP has been well developed and widely used in target recognizing and classification. The estimation results of a cone shaped target are present and compared at the end of the paper. To assure the reliability of the simulation,the bistatic H RRP is obtained through the scattering field data calculated by a fullwave numerical method,FE-BI-MLFMA.

Time trends in myopia and high myopia prevalence in young university adults in China

AIM:To investigate time trends in myopia and high myopia prevalence over 6y among young university adults in China.METHODS:This is a 6-year series cross-sectional study from 2016 to 2021.Totally 4910 freshmen were enrolled and completed a questionnaire concerning age,gender,and disease history.Students with eye diseases were excluded after a detailed eye examination.The refractive status was measured by non-cycloplegic objective refraction and ocular parameters were measured by Lenstar 900.The examination followed the same protocol each year.Trends over time in myopia and high myopia prevalence,as well as ocular biometry parameters,were analyzed.RESULTS:From 2016 to 2021,the axial length(AL)and corneal radius(CR)increased significantly(P=0.002 for AL;P=0.04 for CR).However,the spherical equivalent(SE)and the ratio of axial length to the corneal radius(AL/CR)did not change significantly(P=0.59 for SE;P=0.24 for AL/CR).The frequency of AL≥26.0 mm increased from 26.6%in 2016 to 29.3%in 2021(P=0.05 for trend).The prevalence of myopia and high myopia did not change significantly in our study(P≥0.18).Compared to a similar cross-sectional study conducted 10 years ago,the prevalence of myopia decreased significantly(94.9%vs 91.8%,P<0.001).Whereas the prevalence of high myopia increased largely(18.12%vs 27.6%,P<0.001).CONCLUSION:The prevalence of high myopia increases in young university adults during 10y period.Myopia control should begin earlier in childhood.However,these interventions are still needed for high myopia even in young adulthood.

Changes of optic nerve head microcirculation in high myopia

AIM:To analyze the correlation of age,spherical equivalent(SE),and axial length(AL)with the microcirculation of optic nerve head(ONH)in high myopia(HM).METHODS:In this cross-sectional clinical study,164 right eyes were included.Optical coherence tomography angiography(OCTA)was used to detect ONH vessel density.Eyes were classified based on age,SE,and AL.Groups of Age1,Age2,and Age3 were denoted for age classification(Age1<20y,20y≤Age2<30y,Age3≥30y);Groups SE1,SE2,and SE3 for the SE classification(-9≤SE1<-6 D,-12≤SE2<-9 D,SE3<-12 D);Groups AL1,AL2,AL3,and AL4 for the AL classification(AL1<26 mm,26≤AL2<27 mm,27≤AL3<28 mm,AL4≥28 mm).RESULTS:No significant difference was observed in vessel density among the Age1,Age2,and Age3 groups(all P>0.05)and the SE1,SE2,and SE3 groups(all P>0.05).No significant difference was observed in the intrapapillary vascular density(IVD)among AL1,AL2,AL3,and AL4 groups(P>0.05).However,a significant decrease was found in the peripapillary vascular density(PVD)in the AL1,AL2,AL3,and AL4 groups(F=3.605,P=0.015),especially in the inferotemporal(IT;F=6.25,P<0.001),temporoinferior(TI;F=2.865,P=0.038),and temporosuperior(TS;F=6.812,P<0.001)sectors.The IVD was correlated with age(r=-0.190,P<0.05)but not with SE or AL(P>0.05).The PVD was correlated with AL(r=-0.236,P<0.01)but not with age or SE(P>0.05).CONCLUSION:With the increase of AL,the IVD remains stable while the PVD decreases,especially in the three directions of temporal(IT,TI,and TS).The main cause of microcirculation reduction may be related to AL elongation rather than an increase in age or SE.

STUDY ON BOND LENGTH AND FORCE CONSTANT OF GRAPHITE AT HIGH TEMPERATURE

Some behavior of graphite at high temperature has been studied using X-ray diffraction and Raman spectrat. Recently a model, which can be used to calculate the bond length of sp2 in graphite using the frequency of Raman active mode E2g, has been proposed by E. Fitzer. This model is successful at ambient temperature. But is it suitable at high temperature? In this note, the law of bond length changing with temperature for TG64 type graphite is studied by X-ray diffraction and Raman spectra at

Length optimization of straight line connecting turnout on main line in high-speed railway station yard

Taking the development of high-speed railway in China as background, and referring to the dynamic theory and wheel-rail contact mode, dynamic analysis model was established, considering the setting position of straight lines and running conditions of train in high-speed railway station yard. Using the established model, and choosing vehicle lateral acceleration and wheel suspension as the evaluation indexes, dynamic characteristic of vehicle traveling in turnout and adjacent area on main line was analyzed, and effects on travelling safety and stability of train aroused by length variation of straight lines were calculated based on analyzing the damping rules of vibration. The results show that, a certain length of straight lines can alleviate the vibration aroused in turnout and curve(turnout), length of straight lines connecting turnouts in different sections on main line was proposed to meet the demand of traveling stability, and shortening or cancelation of straight line for the scale limitation of station yard has less influence on operation safety of train.

以数字技术推动人口高质量发展——基于健康人力资本的跨国实证研究

数字技术在促进经济增长和改善社会福祉方面发挥了积极作用,成为实现经济和社会高质量发展的重要引擎。数字技术是促进健康人力资本积累的重要途径和实现人口高质量发展的关键支撑。本文从理论层面系统阐述了数字技术促进健康人力资本积累的逻辑机制,并采用全球118个国家1990—2020年跨国面板数据,结合不同国家经济发展水平差异,从人口“生命长度和生命质量”两个维度,实证检验数字技术对健康人力资本积累的具体影响。研究发现,数字技术在大健康领域的广泛应用,有助于降低人口死亡率、提高人口健康预期寿命,进而促进健康人力资本积累;其作用途径主要通过提高政府卫生支出效率、提升数字健康素养、增加闲暇时间和促进环境改善四个路径来实现;数字技术在改善健康人力资本方面的差异与国家经济发展水平差距密切相关。基于以上分析,研究认为应加大医疗技术创新,发挥新型举国体制的优势,集中力量技术攻关,实现现代数字技术、医疗健康大数据、医疗全流程、医疗健康行业相关方多要素融合,创新中国式精准医疗发展模式。

数字化转型、创新发展与制造业价值链高质量发展

创新驱动发展战略背景下,企业数字化转型对制造业价值链高质量发展具有重要意义。采用2007—2021年沪深A股制造业上市企业数据,从价值链上游度即“强链”和价值链长度即“延链”双重视角,探析企业数字化转型对制造业价值链高质量发展的影响效果、作用机制与异质性特征。研究结果表明:企业数字化转型从“强链”和“延链”两方面推动了制造业价值链高质量发展,且该结论通过了稳健性检验。作用机制检验表明,企业创新发展在此过程中具有显著的正向传导作用。异质性分析表明,在非国有制企业、技术密集型行业、劳动密集型行业和创新引领型城市,企业数字化转型通过“强链”和“延链”推动制造业价值链高质量发展的效果更为显著。为此,在城市层面应健全数字化转型治理体系,在行业层面应加快“新基建”建设进程,促进数字化均衡发展,在企业层面应鼓励以强带弱、协同发展,为企业数字化转型提速增质。

一种基于关联程度的高效用数量比频繁模式挖掘算法

高效用频繁模式挖掘算法运用数据项的重要度信息,能够从数据中挖掘出更重要的频繁模式,而高效用数量比频繁模式挖掘算法可以进一步研究频繁模式中数据项的数量比例关系,是目前数据挖掘领域中的研究课题。从提高算法性能和实用性的角度出发对高效用数量比频繁模式挖掘算法进行优化,提出了一种基于关联程度的高效用数量比频繁模式挖掘算法RHUQI-Miner。RHUQI-Miner首先提出关联程度的概念,依据关联程度构建项目关联程度结构,并给出关联剪枝优化策略,寻找关联程度更高的项目集合,减少冗余和无效的频繁模式;随后运用修正模式长度策略,修正挖掘过程中项集的效用信息,使算法可根据实际数据情况控制输出频繁模式的长度,进一步提升算法的性能,提高算法的实用性。通过对RHUQI-Miner在动车组PHM系统车载故障数据集上的实验结果进行分析,表明该算法能够有效减少挖掘过程中的时间以及内存消耗,可以得出该算法适用于铁路实际数据和业务的有效结论。