Intraocular retinal thickness asymmetry in early stage of primary open angle glaucoma and normal tension glaucoma

AIM： To investigate the intraocular retinal thickness asymmetry of peripapillary retinal nerve fiber layer（pR NFL） and macular layers measured by spectral-domain optical coherence tomography（SD-OCT） in patients with early stage of primary open angle glaucoma（POAG） and normal tension glaucoma（NTG）.METHODS： A total of 117 patients with early stage of glaucoma（54 patients with POAG and 63 patients with NTG） and 32 normal subjects were recruited for the study. The pR NFL thickness, total macular layer（TML） thickness, and isolated inner macular layer（IML） thickness were measured by SD-OCT. Hemisphere TML thickness asymmetry measured by the posterior pole asymmetry scan was evaluated. Thickness differences of pR NFL and IML between superior and inferior quadrants were calculated. Asymmetry indices（AIs） of the p RNFL, TML and isolated IML were also computed. Areas under the receiver-operating characteristic curves（AROCs） were generated to determine the diagnostic capabilities of different parameters. RESULTS： Intraocular p RNFL thickness differences and AIs between the superior and inferior quadrants were significantly different between normal and NTG groups（P=0.009 and P〈0.001, respectively）. Intraocular p RNFL thickness differences and AIs between the temporal-superior and temporal-inferior sectors were also significantly different between normal and NTG groups（P=0.035 and P〈0.001, respectively）. The thickness differences and AIs of TML between superior and inferior hemispheres were significantly different between normal and NTG groups（P=0.001 and P=0.001, respectively） and between normal and POAG groups（P=0.032 and P=0.020, respectively）. The thickness differences and AIs of macular ganglion cell layer（mG CL） between superior and inferior quadrants were significantly different between normal and NTG groups（P=0.013 and P=0.004, respectively）, and between NTG and POAG groups（P=0.015 and P=0.012, respectively）. The thickness difference of TML between superior and inferior hemispheres showed the highest diagnostic capability for early NTG eyes（AROC=0.832）.CONCLUSION： Intraocular retinal thickness asymmetry in pR NFL, TML and mG CL are found in early stage of NTG. Hemisphere TML thickness asymmetry is also found in POAG eyes. Asymmetry analysis of retinal thickness can be an adjunctive modality for early detection of glaucoma.

Macular Thickness by Optical Coherence Tomography in Normal Togolese Melanoderma Subjects: A Case Study of 338 Eyes

Objective: Maculopathies are more and more frequent. For the follow-up of its evolution and therapy, it seems important for us to determine the baseline in normal subjects by Optical Coherence Tomography (OCT). The goal here is to determine the acceptable range of macular thickness in normal black subjects in Lomé. Methodology: This is a retrospective study over a 6-month period. It did not include all patients with retinopathy of any cause, maculopathy, and glaucoma. The analyzed variables were the average macular thickness, the central macular thickness, and the total macular volume. Results: Out of the 433 macular OCT performed, 191 patients were selected;a total of 338 eyes. These included 96 men and 95 women. A sex ratio was 1.01. The median age was 44.1 years with extremes ranging from 10 to 70 years. The average macular thickness was 263.4 μm for the right eye and 263.7 μm for the left eye. The central macular thickness was 174.1 μm for the right eye and 173.3 μm for the left eye. The total macular volume was 7.4 in both eyes. Discussion: No significant statistical difference existed between the two sexes. The average macular thickness found in this study was within the range of normality observed in the literature, which is between 216 and 288 μm. Conclusion: The average macular thickness of the normal subject in Lomé was 263.4 μm.

Finite element analysis on stresses field of normalized layer thickness within ceramic coating on aluminized steel

Multilayer ceramic coatings were fabricated on steel substrate using a combined technique of hot dipping aluminum(HDA) and plasma electrolytic oxidation(PEO). A triangle of normalized layer thickness was created for describing thickness ratios of HDA/PEO coatings. Then, the effect of thickness ratio on stresses field of HDA/PEO coatings subjected to uniform normal contact load was investigated by finite element method. Results show that the surface tensile stress is mainly affected by the thickness ratio of Al layer when the total thickness of coating is unchanged. With the increase of Al layer thickness, the surface tensile stress rises quickly. When Al2O3 layer thickness increases, surface tensile stress is diminished. Meanwhile, the maximum shear stress moves rapidly towards internal part of HDA/PEO coatings. Shear stress at the Al2O3 /Al interface is minimal when Al2O3 layer and Al layer have the same thickness.

Size dependent free vibration analysis of functionally graded piezoelectric micro/nano shell based on modified couple stress theory with considering thickness stretching effect

Higher-order shear and normal deformation theory is used in this paper to account thickness stretching effect for free vibration analysis of the cylindrical micro/nano shell subjected to an applied voltage and uniform temperature rising.Size dependency is included in governing equations based on the modified couple stress theory.Hamilton’s principle is used to derive governing equations of the cylindrical micro/nano shell.Solution procedure is developed using Navier technique for simply-supported boundary conditions.The numerical results are presented to investigate the effect of significant parameters such as some dimensionless geometric parameters,material properties,applied voltages and temperature rising on the free vibration responses.

Age related changes of the central lamina cribrosa thickness, depth and prelaminar tissue in healthy Chinese subjects

AIM： To investigate the variation in the central lamina cribrosa thickness（cLCT）, and the central anterior lamina cribrosa surface depth（cALCSD）, as well as the central prelaminar tissue thickness（cPLTT） related to age in healthy Chinese subjects.METHODS： A total of 96 eyes from 96 Chinese healthy subjects were recruited. According to age, the 96 cases were divided into three groups： the young group（YG, 18-39 y）, middle-age group（MG, 40-59 y） and older-age group（OG, 60 y and above）. Lamina cribrosa images were obtained from all participants using radial linear protocol by enhanced depth imaging spectral-domain optical coherence tomography. The cLCT, cALCSD and cPLTT were calculated from the average value of the lamina cribrosa thickness, anterior lamina cribrosa surface depth and prelaminar tissue thickness in the optic nerve head（ONH） centre point and paracentral points（150 μm from the centre point in the horizontal and vertical directions）. RESULTS： For the total subjects, the mean cLCT, c ALCSD and cPLTT were 235.18±41.27, 358.02±93.80 and 182.02±92.11 μm, respectively. No statistically significant differences in cLCT, cALCSD or cPLTT were found between gender and different eyes（P=0.27-0.92）. The cLCT of the OG was the thickest among the three groups, while the c PLTT of the YG was the thickest among the three groups（P〈0.05）. Age was positively correlated with cLCT（r=0.42, P〈0.001）, and negatively correlated with cPLTT（r=-0.24, P=0.02）. No significant correlation was found between the age and cALCSD（r=-0.06, P=0.55）. And no correlation has been found between axial length and cLCT, cALCSD and c PLTT（P=0.11-0.81）.CONCLUSION： The impact of age on the cLCT and the cPLLTT should be taken into account when analysing glaucoma and other diseases related to lamina cribrosa.

Experimental research on oil fi lm thickness and its microwave scattering during emulsifi cation

Synthetic Aperture Radar(SAR) plays a major role in identifying oil spills on the sea surface.However,obtaining information of oil spill thickness(volume) is still a challenge.Emulsification is an important process affecting the thickness and normalized radar cross section(NRCS) of oil film.Experiments of crude oil emulsification with C-band fully-polarized scatterometer were conducted combining airborne hyperspectral imaging spectrometer and 3 D laser scanner observation data,to provide experimental parameters and method to support accurate remote sensing monitoring on marine oil spill.It is further proved that through quantitative homogeneous emulsified oil spill experiments,to a certain extent,the NRCS of oil film increased during the emulsification process of crude oil.The backscattering mechanism of crude oil emulsification was explored using a semi-empirical model(SEM);the change of oil film NRCS was modulated by its dielectric constant and surface roughness,in which the dielectric constant showed a dominant effect.The relationship between thickness and NRCS of oil film was studied under two experimental conditions.The differences of NRCS between oil film and adjacent seawater(Δσ~0) and the damping ratio(DR) were found to have a linear relationship with oil thickness,which were best in the vertical polarization mode(VV) at 45° incident angle during the quantitative crude oil homogeneous emulsification process.In the natural emulsification process of continuous oil spill in which oil film was mixed with both crude oil and emulsified oil,an empirical equation of oil film thickness is preliminarily established.The Δσ~0,DR,and the empirical equation of oil film thickness were applied to the marine continuous oil spill incident on a 19-3 oil platform with spaceborne SAR image and successfully explained the distribution of the relative thickness of the oil film.

DELIBERATlON TO THE DEFINITION OF TOOTH THICKNESS FOR INVOLUTE HELICAL GEAR IN INTERNATIONAL STANDARD ISO1122／1

The definitions of the normal chordal tooth thichness and the constant chord in interna-tional standard ISO 1122/1-1983(E) are analyzed according to the basic principle of involute cy-lindrical gear geometry. It is pointed out that in the case of spur gears, the two definitions arerespectively identical with generally recognized traditional formulas, but in the case of helical gears,they are respectively contradictory with their traditional formulas. The general principle of themethod of the two-point measuring for the tooth thickness of gears is analysized, and the calcula-tion formulas of the two-point measuring for the tooth thickness of the involute helical gear ispresented. It is proved theoretically that a constant chord can be measured with the method of thetwo-point measuring (with the tooth thickness caliper) while normal chordal tooth thickness cannot be measured with the tooth thickness caliper (the method of the two-point measuring). The is-sues of the two definitions of the tooth thickness in the international standard are analysed outagain in measurng.

颈动脉斑块负荷联合超声定量参数在评估急性脑梗死患者神经功能缺损程度中的应用价值

目的探讨颈动脉斑块负荷联合超声定量参数在评估急性脑梗死(ACI)患者神经功能缺损程度中的应用价值。方法选取2020年1月至2023年1月河南中医药大学第一附属医院收治的106例ACI患者作为研究对象,所有患者均接受彩色多普勒超声检查。采用国立卫生研究院卒中量表(NIHSS)评估ACI患者神经功能缺损程度,并以此分为轻度缺损组、中度缺损组及重度缺损组。比较不同组别ACI患者颈动脉斑块负荷指标与超声定量参数,使用Pearson相关性检验颈动脉斑块负荷指标、超声定量参数与患者NIHSS评分的相关性;绘制受试者工作特征(ROC)曲线分析颈动脉斑块负荷指标联合超声定量参数对ACI患者神经功能缺损程度的评估价值。结果106例ACI患者中,轻度、中度缺损组各35例,重度缺损组36例。重度缺损组斑块厚度、管壁面积、血管总面积及标准化管壁指数(NWI)高于中度、轻度缺损组,且中度缺损组高于轻度缺损组,差异均有统计学意义(P<0.05);重度缺损组管腔面积低于中度、轻度缺损组,中度缺损组低于轻度缺损组,差异均有统计学意义(P<0.05)。重度缺损组颈总动脉内膜中层厚度(IMT)、舒张末期血流速度(EDV)高于中度、轻度缺损组,中度缺损组高于轻度缺损组,差异均有统计学意义(P<0.05);重度缺损组颈总动脉收缩期峰值血流速度(PSV)低于中度、轻度缺损组,中度缺损组低于轻度缺损组,差异均有统计学意义(P<0.05)。Pearson相关性检验显示,斑块厚度、管壁面积、血管总面积、NWI、IMT、EDV与NIHSS评分呈正相关(r>0,P<0.05),PSV、管腔面积与NIHSS评分呈负相关(r<0,P<0.05)。绘制ROC曲线,结果显示,颈动脉斑块负荷指标联合超声定量参数对中度、重度神经功能缺损均有较高的评估价值,曲线下面积(AUC)分别为0.936、0.987。结论颈动脉斑块负荷联合超声定量参数可有效评估ACI患者的神经功能缺损程度。

混合型缓冲回填材料劈裂抗拉强度尺寸效应统计分析

高放废物深地质处置库中的混合型缓冲回填材料是由膨润土和各类掺合料压实而成的多相复合材料,在多组分混合与压制过程中其内部孔洞、微裂隙等缺陷随机分布,即使在相同试验条件下其抗拉强度值也表现出较大的变异性。为阐明试验试样厚径比对混合型缓冲回填材料劈裂抗拉强度的影响规律,针对不同厚径比试样开展了大量的巴西劈裂试验,探讨了不同厚径比试样抗拉强度统计特征及分布概型。结果表明:混合型缓冲回填材料试样劈裂抗拉强度与圆盘厚径比呈显著的幂函数关系,显著性检验结果小于0.05。混合型缓冲回填材料劈裂抗拉强度的均值、极差、标准差及变异系数都呈现出明显的尺寸效应。圆盘厚径比为1.0时,劈裂抗拉强度的极差、标准差及变异系数均最小,从统计特征来看,建议进行巴西劈裂试验时圆盘厚径比设定为1.0。根据K-S检验和有限比较法知圆盘厚径比不同,劈裂抗拉强度最优分布概型也不相同。常用的4种概率分布形式中的正态分布和威布尔分布能更好地描述混合型缓冲回填材料劈裂抗拉强度分布规律。

针对Landsat遥感影像的去云处理方法研究

遥感传感器获取的光学影像中部分区域不可避免存在云遮挡现象。本文选择的实验区位于西昆仑山的古里雅冰帽,将影像上的云区域划分为薄云与厚云,针对Landsat遥感影像进行去云处理方法研究。结果表明:针对Landsat遥感影像,直方图匹配和小波融合两种方法能够有效去除薄云;构建的归一化厚云检测模型能够较好地对厚云进行检测;匹配算法是当前比较有效的厚云处理方法。

Comparisons of ganglion cell-inner plexiform layer loss patterns and its diagnostic performance between normal tension glaucoma and primary open angle glaucoma: a detailed, severity-based study

AIM: To evaluate the patterns of macular ganglion cell-inner plexiform layer(GCIPL) loss in normal tension glaucoma(NTG) and primary open angle glaucoma(POAG) in a detailed, disease severity-matched way;and to assess the diagnostic capabilities of GCIPL thickness parameters in discriminating NTG or POAG from normal subjects.METHODS: A total of 157 eyes of 157 subjects, including 57 normal eyes, 51 eyes with POAG and 49 eyes with NTG were enrolled and strictly matched in age, refraction, and disease severity between POAG and NTG groups. The average, minimum, superotemporal, superior, superonasal, inferonasal, inferior, and inferotemporal GCIPL thickness, and the average, superior, temporal, inferior, and nasal retinal nerve fiber layer(RNFL) thickness were obtained by Cirrus optical coherence tomography(OCT). The diagnostic capabilities of OCT parameters were assessed by area under receiver operating characteristic(AUROC) curves. RESULTS: Among all the OCT thickness parameters, no statistical significant difference between NTG group and POAG group was found(all P>0.05). In discriminating NTG or POAG from normal subjects, the average and inferior RNFL thickness, and the minimum GCIPL thickness had better diagnostic capabilities. There was no significant difference in AUROC curve between the best GCIPL thickness parameter(minimum GCIPL) and the best RNFL thickness parameter in discriminating NTG(inferior RNFL;P=0.076) and indiscriminating POAG(average RNFL;P=0.913) from normal eyes.CONCLUSION: Localized GCIPL loss, especially in the inferior and inferotemporal sectors, is more common in NTG than in POAG. Among all the GCIPL thickness parameters, the minimum GCIPL thickness has the best diagnostic performance in differentiating NTG or POAG from normal subjects, which is comparable to that of the average and inferior RNFL thickness.

QAS联合QIMT技术对正常高值血压患者颈动脉硬化的研究

目的应用动脉僵硬度定量检测(QAS)技术联合血管内-中膜分析(QIMT)技术评价正常高值血压患者颈动脉的结构与功能。方法根据血压水平将接受颈动脉超声及QAS联合QIMT检查的人群分为血压正常组(82例)、正常高值血压组(90例)和高血压组(68例)。应用QAS技术测量双侧颈动脉的弹性参数:扩张系数(DC),顺应性系数(CC),僵硬度系数(α、β),脉搏波传导速度(PWV);应用QIMT技术测量双侧颈动脉内-中膜厚度(IMT);收集受检者体质量指数(BMI)、总胆固醇(TC)、三酰甘油(TG)、高密度脂蛋白胆固醇(HDL-C)和低密度脂蛋白胆固醇(LDL-C)。比较各组不同性别间颈动脉各弹性参数及IMT,正常高值血压患者颈动脉左侧和右侧各弹性参数及不同水平血压各组颈动脉各弹性参数及IMT,分析血脂与各参数的相关性。结果正常高值血压组男性颈动脉IMT高于女性(P<0.05),左侧和右侧颈动脉IMT、DC、CC、α、β及PWV比较,差异均无统计学意义;与血压正常组相比,正常高值血压组与高血压组的IMT、α、β、PWV增大,DC、CC减小;高血压组PWV较正常高值血压组增大(P<0.05)。正常高值血压患者HDL-C与DC、CC呈正相关,与α、β、PWV呈负相关(P<0.01);LDL-C与DC、CC呈负相关,与α、β、PWV呈正相关(P<0.01)。结论应用QAS联合QIMT技术发现正常高值血压患者颈动脉弹性减低,IMT增厚。

THEORY OF THICK-WALLED SHELLS AND ITS APPLICATION IN CYLINDRICAL SHELL

In this paper, a theory of thick-walled shells is established by means of Hellinger-Reissner's variational principle, with displacement and stress assumptions. The displacements are expanded into power series of the thickness coordinate. Only the first four and the first three terms are used for the displacements parallel and normal to the middle surface respectively. The normal extruding and transverse shear stresses are assumed to be cubic polynomials and to satisfy the boundary stress conditions on the outer and inner surfaces of the shell. The governing equations and boundary conditions are derived by means of variational principle. As an example, a thick-walled cylindrical shell is disscussed with the theory proposed. Furthermore, a photoelastic experiment has been carried out, and the results are in fair agreement with the computations.

子宫内膜非典型增生的临床检验指标分析

目的 分析子宫内膜非典型增生(Endometrial Atypical Hyperplasia,EAH)的临床检验指标,寻找危险因素及诊断预测指标,为疾病的预防及筛查诊断提供新思路。方法 收集2020年6月至2021年12月于首都医科大学附属北京妇产医院妇科行宫腔镜治疗的211例患者的临床资料,EAH患者为研究组(n=107),宫腔粘连患者为对照组(n=104)。回顾性分析两组患者的妊娠次数、初潮年龄、体质指数(Body Mass Index,BMI)、实验室检验指标及子宫内膜厚度、子宫体积等项目,并探寻疾病相关危险因素及有效诊断预测指标。结果 研究组BMI、血小板计数、低密度脂蛋白胆固醇、子宫内膜厚度及子宫体积均高于对照组,差异有统计学意义(P<0.001);研究组甘油三酯高于对照组,差异有统计学意义(P<0.01);研究组国际标准比值(International Normalized Ratio,INR)及高密度脂蛋白胆固醇(High Density Lipoprotein Cholesterol,HDL-C)低于对照组,差异有统计学意义(P<0.001);研究组妊娠次数低于对照组,差异有统计学意义(P<0.05)。HDL-C、INR、子宫内膜厚度及子宫体积为EAH的独立危险因素(P<0.05),其中子宫内膜厚度危险性最大(OR=5.984)。子宫体积预测EAH的受试者工作特征曲线下面积为0.947(95%CI:0.912~0.982),优于子宫内膜厚度。结论 HDL-C、INR、子宫内膜厚度及子宫体积为EAH的独立危险因素,其中子宫内膜厚度危险性最大,而子宫体积对疾病预测有较好的临床意义。应在工作中提高对以上检验检查指标的重视,并对临床诊断截断值的确定进行深入研究,以利于疾病的快速筛查及预防。

不同形式正断层采动应力及瓦斯赋存规律研究

为了探究不同形式正断层的采动应力及瓦斯赋存规律,以界沟煤矿为工程背景,采用FLAC3D数值模拟研究了工作面过断层时的采动应力演化规律,通过在界沟煤矿西一采区进行现场测试,得出了不同类型正断层附近的瓦斯赋存规律。研究表明:正断层随着断裂带宽度的增大,断层带的影响范围也越大;断层带的卸压程度随断层倾角的增大,而逐渐变小,随断层落差的增大,而逐渐增大;阶梯式、地堑式、地垒式断层组合中间区域呈两边低中间高的应力分布规律,并且卸压程度要强于断层组合外侧区域;当煤厚突增发生在正断层上盘应力增高区附近时应力相对于非构造区域会增大约1.22倍,受叠加应力影响会出现应力集中现象;瓦斯含量与煤层厚度呈正相关关系,正断层附近煤层厚度与瓦斯含量总体呈现逐渐减小的趋势,并且断层落差越大断层附近的瓦斯含量和K1值就越小。当工作面推进到断层附近时应注意煤层厚度变化,加强瓦斯相关参数测试,提前预测风险,有针对性地做好防治措施。

基于图像边缘检测和法向探测的导线覆冰监测方法

输电线路导线覆冰是影响电网安全稳定运行的主要隐患之一,现有的覆冰监测存在传感器监测类型单一、精度低、不能实时处理等突出问题。提出了一种基于图像边缘检测和法向探测的覆冰监测方法。该方法首先对线路的微拍图像进行预处理,并采用八邻域追踪等算法进行边缘检测获得导线最长边,进一步设计了边缘法向探测的覆冰厚度检测方法。此法不仅可以判断是否存在覆冰,而且可以计算出导线的覆冰厚度。基于ARM 8.2处理器的嵌入式系统实验结果表明,所提出的方法实时检测导线覆冰厚度的相对误差不超过9%,且比现有的称重法降低了约6.1%。

激光焊接技术导入工程机械结构件制造的范式研究

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