Effect of prisms on visual acuity,contrast sensitivity and nystagmus in patients with albinism

AIM:To investigate the effect of using base-out prisms on nystagmus,visual acuity and contrast sensitivity in patients with albinism.METHODS:In this interventional study,patients with albinism who had nystagmus were enrolled.A comprehensive eye exam was conducted,which included refraction,assessment of far and near vision acuity,and contrast sensitivity measurements.To check for the nystagmus,a videonystagmography was used.The tests were carried out in three modes:without any correction,with optical correction,and with correction using base-out prisms in three different powers,including 4,6,and 8 prism diopters.RESULTS:Totally 23 patients with average age of 28.65±12.13 were examined.It was found that the use of optical correction and optical correction with prisms resulted in a statistically significant improvement in both far(at least:P<0.006)and near visual acuity(at least:P<0.001 except for prism 8;P<0.02).In addition,contrast sensitivity significantly improved at all low and medium frequencies except for correction with prism 8 in frequency 1.5(at least:P<0.01 except for prism 4,frequency 6;P=0.04).no significant improvement was observed in the evaluation of nystagmus characteristics.CONCLUSION:Optical correction with a prism can improve visual acuity and some spatial frequencies,but failed to improve nystagmus parameters.

Advances in the Theory of Conjugation for Reflecting Prisms in China

The achievements made in China in the field of the theory of conjugation for reflecting prisms are outlined which mainly includes 6 theorems, 2 corollaries, over 30 formulae, 4 matric operators, 20 characteristic parameters, a new principle for dassification, and a new system of graphical tabulation for reflecting prisms. As an approach to developing the theory, an imaginary physical model called 'rigid body's kinematics model' has been creatively initiated to simulate the real physical phenomena of both image formation and image motion for reflecting prisms. Such a method of treatment has been successfully making the evolving theory more complete, more systematic, more generalized, and unique as well.

Improvement of visual acuity in children with anisometropic amblyopia treated with rotated prisms combined with near activity

·AIM: To evaluate the efficacy of a new modality for improving visual acuity (VA) in pediatric patients with anisometropic amblyopia. · METHODS: Retrospective and interventional case series. Medical records of 360 children with anisometropic amblyopia treated with a modality that included rotated prisms, lenses, and near activities from January 2008 to January 2012 were analyzed. Characteristics such as improvement of VA and contrast sensitivity in amblyopic eyes and resolution of amblyopia (VA ≤ 0.1logMAR or a difference of ≤ 2 lines in logMAR between the eyes) were assessed. ·RESULTS: Among the patients, the mean VA of the amblyopic eyes improved from 0.48logMAR (SD=0.16) to 0.12logMAR (SD =0.16) and the mean VA improvement was 0.36logMAR (SD =0.10, P【0.001). Resolution of amblyopia was achieved in 233 of 360 patients (64.72%). The mean time for resolution of amblyopia was 8.05 weeks (SD=4.83) or 14.14 sessions (SD=8.76). Among the study group, refraction error did not change significantly after treatment (P=0.437). We found that better baseline VA may be related to success and shorten the time to amblyopic resolution. ·CONCLUSION: VA and contrast sensitivity improved with rotated prisms, correcting lenses, and near activities in children with anisometropic amblyopia. The VA improvement by this modality was comparable to other methods. However, the time to resolution of amblyopia was shorter with this method than with other modalities. Rotated prisms combined with near acuity could provide an alternative treatment in children with anisometropic amblyopia who can’t tolerant traditional therapy method like patching.

Multi-frequency focusing of microjets generated by polygonal prisms

We systematically investigate the power distribution characteristics of microjets generated by prismatic scatterers with different shapes at sub-THz region(λ = 8.57 mm). Among these prismatic scatterers, the hexagonal-type one shows better focusing feature than the others. Aiming at the hexagonal-type one, we propose a double-layer scatterer composed of a Teflon hexagonal prism as an outer layer and a semiconductor cuboid as an inner layer. Aiming at the double-layer scatterer, we further study the effects of refractive index, size, and shape of the inner cuboid on microjet’s features. The study allows us to present an optimized double-layer scatterer, which has a side length λ/2(λ) and a refractive index 2.0(1.4) for the inner(outer) layer. We show that the optimized scatterer can produce an ultra-strong, ultra-narrow microjet with a power enhancement of;0 and a full width at half maximum(FWHM) of;0.26λ, and the microjet is just located at the output face. The microjet keeps compact within the distance range of λ from the output face. These features and effects are explained from the viewpoint of ray optics theory. According to the optimized double-layer scatterer, we further study the multi-frequency focusing features of the microjets, and find that the microjet remains good features at harmonic frequencies 2f_(0) and 3f_(0). In addition, we investigate the effect of an Au sphere presence in the center of the microjet on the power distribution. The results show that a spherical dark spot with a size similar to that of the Au sphere emerges in the area where the Au sphere is placed. The feature can be used to measure the size of a metallic particle.

Research on refractive index of optical cement used in Glan-Thompson prisms

The influence of the refractive index n2 of optical cement on the structure angle, field angle, and transmission of Glan-Thompson prism has been studied in detail. The results show that the structure angle will increase with the decrease of n2 under the condition of the largest field angle. Thus, the ratio of length to width （L/A） of the prism will decrease, which means more materials can be saved. When the value of L/A is 3.0 or 2.5 in the routine design, the field angle will firstly increase and then decrease with the increment of n2. Two routine designs with the n2 values of 1.47 and 1.45 have the optimal field angle. In addition, n2 also has great influence on light intensity transmittance of the prism. Considering all these factors, it will be the best choice with L/A = 2.5 and n2 = 1.45 - 1.46.

Predicting bathymetry based on vertical gravity gradient anomaly and analyses for various influential factors

The prediction of bathymetry has advanced significantly with the development of satellite altimetry.However,the majority of its data originate from marine gravity anomaly.In this study,based on the expression of vertical gravity gradient(VGG)of a rectangular prism,the governing equations for determining sea depths to invert bathymetry.The governing equation is solved by linearization through an iterative process,and numerical simulations verify its algorithm and its stability.We also study the processing methods of different interference errors.The regularization method improves the stability of the inversion process for errors.A piecewise bilinear interpolation function roughly replaces the low-frequency error,and numerical simulations show that the accuracy can be improved by 41.2%after this treatment.For variable ocean crust density,simulation simulations verify that the root-mean-square(RMS)error of prediction is approximately 5 m for the sea depth of 6 km if density is chosen as the average one.Finally,two test regions in the South China Sea are predicted and compared with ship soundings data,RMS errors of predictions are 71.1 m and 91.4 m,respectively.

Independent and continuous third-order dispersion compensation using a pair of prisms

The dispersion of a pair of prisms is analyzed by means of a ray-tracing method operating at other than tip-to-tip propagation of the prisms, taking into consideration the limited spectral bandwidth. The variations of the group delay dispersion and the third-order dispersion for a pair of prisms are calculated with respect to the incident position and the separation between the prisms. The pair of prisms can provide a wide range of independent and continuous third-order dispersion compensation. The effect of residual third-order dispersion on the pulse contrast ratio and pulse duration is also calculated. The residual third-order dispersion not only worsens the pulse contrast ratio, but also increases the pulse duration to the hundreds of femtosecond range for a tens of femtosecond pulse, even when the residual thirdorder dispersion is small. These phenomena are helpful in compensating for the residual high-order dispersion and in understanding its effect on pulse contrast ratios and pulse durations in ultrashort laser systems.

PRISM媒体分析平台在IP播出的应用

当前,广播电视的传输技术正在实现从SDI技术向IP技术的传输架构过渡,如何监测SDI/IP混合环境中的信号数据仍然是挑战。本文介绍了PRISM媒体分析平台实际应用中的插件选项,分析其中监测的IP系统数据,研究将多个IP信号与PRESET插件结合的可行性。

Space-time prisms in multimodal supernetwork-Part 2:Application for analyses of accessibility and equality

Space-time prism(STP)is a fundamental concept in time geography and has been predominately constructed in unimodal transportation networks.Due to the vast trip chaining options by private vehicles and public transportation,it was challenging to construct STP over multimodal transportation networks.We previously put forward an efficient method to narrow down the action space for trip chaining and construct STPs effectively in a multimodal supernetwork.This study applies multimodal STP modeling to measure space-time accessibility and equality of daily activity opportunities.Two equality measures(Gini coefficient and 20:20 ratio)are derived from two space-time accessibility measures based on delineated STPs.We examine the equality of access to shopping and leisure opportunities in the Rotterdam-The Hague metropolitan area,the Netherlands.The results show the effects of various factors on accessibility and equality.It is found that although the study area has relatively low inequality using single modes,multimodal trip chaining further reduces inequality to access the distributed space-time opportunities.

发达国家重大科技计划研究及对我国标准化科研的启示——以日本PRISM计划为例

随着全球化的发展,世界主要经济体将“标准化战略”作为一种通过构建技术壁垒提高国际竞争力的重要手段。本文通过以日本PRISM计划下设的“推进标准利用支持专项”为例,分析日本政府推进政府与私营部门协同开展标准化工作的基本思路、政策布局和具体做法,为我国政府与私营部门协调开展标准化工作,参与国际竞争提供参考。

基于WPF和Unity3D的机器视觉虚拟仿真教学平台研究

本文研究了一种机器视觉虚拟仿真教学平台,旨在提高教学效果和教学体验。该平台由控制端和虚拟仿真端2部分组成,控制端采用WPF和Prism框架编写,虚拟仿真端采用Unity搭建,2个部分使用Socket进行通讯。控制端包括大量机器视觉处理算子,可以对虚拟仿真端返回的图片进行机器视觉处理,以达到教学效果。本文详细介绍了平台的架构设计、采图指令及图像处理算子、平台应用案例等方面,并分析了平台的优势、局限性以及对未来的展望。

Prism彩色电子纸在装饰应用场景中的创新实践

基于Prism彩色电子纸原理,通过与其他电子纸技术对比分析,着重介绍了Prism彩色电子纸的原理、种类和特点,以及其在指示牌、温湿度计、服饰类、建筑类等装饰型场景的创新实践,并对Prism未来的发展方式进行展望。

ALOS卫星PRISM影像严格几何模型的构建与验证

根据ALOS卫星全色遥感立体测绘仪(PRISM)传感器的成像原理,利用卫星影像的辅助数据文件构建无需地面点的严格几何模型。试验发现,直接利用星上提供的轨道姿态数据和严格几何模型进行无控制定位精度较差,经分析发现ALOS卫星辅助数据文件中提供的CCD侧视角可能存在固定的系统误差,经校正后能使定位精度得到显著提高,达到ALOS卫星标称的几何定位精度。不同景影像定位精度的差异可能的原因是CCD侧视角的细微变化。

基于PRISM和泰森多边形的地形要素日降水量空间插值研究

以黑河流域河西走廊中段地区为例,利用该研究区年、月降水与地形间较强的相关性特点,在PRISM方法的基础上对该地区日降水量进行了空间插值计算。文章提出了以月降水量的PRISM空间插值结果为该月逐日降水空间分布的参考本底,利用泰森多边形方法确定空间日降水的概率,从而实现黑河流域河西走廊中段地区日降水的空间制图方法,并对该方法得到的日降水时空数据集进行了误差分析和评估。分析结果表明,这一方法简单可靠,满足分布式水文模型或相关陆表过程分布式模拟对分布式日降水数据时空精度的要求。

基于DEM的地理要素PRISM空间内插研究

利用PRISM模型基于DEM、站点数据和其它空间数据图层内插了气象要素,以便准确表达其空间分布特征。为了比较PRISM空间内插结果,采用GIS常用的Kriging内插、Spline内插等方法分别对降水和气温站点数据进行空间插补,并对内插结果进行精度分析、DEM空间分辨率的影响分析和各个权重因子的影响分析。分析表明,PRISM方法比其它内插方法能够更加精确地表达气象要素的空间分布,更适合于在地形复杂地区地表参数的空间内插。由于气象要素空间分布的复杂性,PRISM内插方法不能完全表达地表参数空间异质性。以后研究中,应在更小的站点影响单元内考虑更多因子利用PRISM方法进行气象要素的空间内插。

ALOS-PRISM遥感影像超分辨率重建

介绍了日本ALOS卫星PRISM三线阵传感器的成像原理和方法,提出了利用PRISM三线阵影像进行超分辨率重建来提高PRISM影像的空间分辨率。提出了新的光流配准算法,该算法将标准互相关配准算法引入到Lucas-Kanade光流配准算法中,大大的减少了误配率,能够有效的消除PRISM Level1级别的影像之间由于地形起伏所引起的变形。同时,改进了影像的高斯退化模型,在超分辨率算法中,引入了可变退化函数,通过交替最小化(AM)算法对可变退化函数进行盲估计,实验结果表明,超分辨率重建影像与插值影像相比,细节清晰很多,有效的提高了影像的分辨率。实验结果说明了本文配准算法可以达到超分辨率重建的亚像素的精度要求,可以应用于航空遥感影像的高精度匹配,同时也说明了将航空遥感影像的退化函数算子分为高斯退化算子和可变退化算子的思想是正确的,符合实际情况。

基于GIS技术的黑河流域地表通量及蒸散发遥感反演

大范围非均匀陆表域的蒸散发计算非常复杂，在寒、旱区更甚。利用遥感和地理信息系统集成的方法，在基于数字高程模型(DEM)的PRISM空间内插方法得到的空间分布的初始气象参数输入的平台上，采用陆表能量平衡算法(SEBAL)，从经过地形校正和大气校正等预处理的TM影像上反演出地表能量通量各分量的空间分布，从而得到黑河流域蒸散发。对使用该方法反演得到的地表通量各分量和日蒸发量的结果分析表明，本算法结果与HEIFI试验中观测到的若干测点结果非常吻合，与白天在黑河流域戈壁沙漠区潜热和蒸散发出现负值、而在绿洲植被区潜热大概为显热4倍左右野外观测结果非常一致，证明该方法对计算黑河流域非均匀陆表能量平衡和蒸散发是有效的。

新闻XML标准的比较与研究

列举当前的主要几种新闻XML标准,进行比较和分析。

竞争情报价值的度量探究

竞争情报既是一种产品,也是一个操作过程。为了确定竞争情报的价值,并有效地管理竞争情报的操作过程,本文分析了国内外的相关研究成果,从“产品观”和“过程观”两个视角探讨了竞争情报价值的可行的度量方法,并对这些度量方法的适用性提出了作者的看法。

PRISM在松花江流域降水分布中的应用研究

基于松花江流域46个国家基准站的年降水资料和分辨率为1 km的数字高程模型(DEM)数据,考虑了距离和高程权重,利用PR ISM(Parameter-elevation Regression on Independent SlopesModel)内插方法计算了松花江流域2000—2004年各年降水量,通过Arcinfo输出了含有地理信息的降水量分布,细致地反映了松花江流域降水量的空间分布状况,并对所用气象站点数据作了交叉验证,误差在可接受范围内。