Reducing treatment zone diameter in orthokeratology and its effect on peripheral ocular refraction

PurposeTo determine whether orthokeratology (OK) induced treatment zone (TZ) diameter can be reduced by altering OK lens design, and if so the impact of modifying TZ diameter on relative peripheral refraction (RPR).Methods16 subjects (mean age 23.4 ± 1.5 years; 8 female) completed the study. Standard (Control) OK lens design (PJ, Capricornia, Australia) or a modified version (Test) where the back optic zone diameter was reduced, and back optic zone asphericity and intermediate lens curves were altered, were worn overnight only for 7-nights in a randomised double masked order, with a minimum 1-week wash out (no lens wear) between lens designs. Full correction of refractive error was targeted. Refraction; best corrected visual acuity (BCVA); RPR (Shin-Nippon NVision-k 5001) along the horizontal and vertical meridians; and corneal topography (Medmont E300) were measured before starting lens wear and in the morning after lens removal after the seventh night of lens wear for both lens designs. TZ diameter and decentration was calculated from corneal topography.ResultsAfter 7-nights of wear both lens designs created -2.00D refraction effect with no significant difference in refractive effect or change to BCVA between the designs. The Test design created a significantly smaller horizontal (4.78 ± 0.37 vs 5.70 ± 0.37 mm, p < 0.001) and vertical (5.09 ± 0.51 vs 5.92 ± 0.51 mm p < 0.001) TZ diameter. The TZ was decentered inferior temporal with no significant difference between designs. There was no significant difference between the lens designs in RPR along the horizontal and vertical meridians at any measurement period.ConclusionsOK induced TZ diameter can be reliably reduced by altering OK lens design without detrimentally effecting lens centration or refractive effect. Reducing TZ diameter did not alter RPR, though measurement artifacts could be responsible for masking an effect. Longitudinal studies are needed to assess whether smaller TZ OK lens designs increase efficacy for slowing progression of myopia.     

基于对比折射法的三维静校正技术及其应用

在地形起伏剧烈、速度和厚度横向变化大的地区，折射静校正技术的应用受到诸多限制，主要表现在不能准确地识别和拾取来自于地下连续地质界面的折射波，使得精确求取的长波长静校正量困难。为此，提出了一种基于对比折射法的三维静校正技术。介绍了这种静校正技术的方法原理和特点，基于对比折射法的折射波至拾取实质上是一个折射层的对比分析解释过程，因此能准确地拾取折射波至，精确地求解低速带的绝对延迟时；然后利用延迟时和近地表速度模型（等效，时深，空变）反演表层模型，最终一次性完成基准面静校正（包含低速带校正和高程校正）。在黄土塬、沙漠以及沙漠和山地的接合部等地区，利用基于对比折射法的三维静校正技术进行静校正处理，使资料的品质得到了明显改善，反射同相轴连续性好，信噪比和分辨率高，构造形态清晰可靠，提高了勘探精度。     

人工免疫原理在网络入侵检测系统中的研究

文章分析了人工免疫系统的原理,简单建立了一种基于否定选择算法的网络入侵检测系统,引入了一种用于异常事件识别的r-字符块匹配规则,并对规则存在的漏洞进行了分析。     

油酸酯与ZDDP复配的摩擦学特性研究

研究了油酸酯与ZDDP复配的润滑油品，其PB值是46号液压油的1．88倍，摩擦行程6h，终止摩擦系数为0．008，是46号液压油终止摩擦系数的1／3，摩擦行程26．0km，摩擦副的磨损量为0．07mg。     

等偏移距自动初至静校正

茅金根 ,梁秀文 ,杨午阳 ,冯有奎 .等偏移距自动初至静校正 .石油地球物理勘探 ,2 0 0 2 ,37(5 ) :4 6 9～ 4 72　　本文提出一种自动计算静校正量的新方法。它首先在等偏移距道集内对相邻道的初至波采用高精度相关构建一个关于炮、检时差的超大矩阵方程 ,然后采用优化统计迭代算法求解炮点和检波点的静校正量 ,并用概率分布函数确定精确的炮、检静校正量 ,最后用误差校正函数消除炮、检静校正误差。实际资料处理结果表明 ,本方法自动、省时、精度高。     

济钢转炉煤气储存加压系统存在缺陷及处理措施

济钢燃气厂针对济钢转炉煤气储存加压系统的设备现状，组织了一次设备大修，大修后煤气柜升降速度提高到了1．0m/min，并解决了加压机前负压等问题。     

硅光电负阻器件的构成原理与分类

将三端负阻器件与硅光电探测器相结合 ,通过新的构思成功地提出并构成了一类新型光电器件——硅光电负阻器件。文中报道了该器件构成的一般性原理 ,以及依据此构成原理确定的分类方法     

Effect of refraction on optical microscopic measurement of internal blood-vessel diameter and its correction

In optical microscopic measurement of internal blood-vessel diameters, the effect of refraction must be taken into account to ensure accuracy of the result. This effect is discussed and an analytical correction formula derived. Phantom blood vessels with known internal and external diameters were used to test the validity of the correction formula. The errors obtained prior to correction were reduced significantly after correction.     

Nonlinear electrical transport in K-TCNQ at low temperatures

A remarkable nonlinearity has been observed for electric transport in K-TCNQ (potassium tetracyanoquinodimethane) quasi-one-dimensional conductor. The negative differential resistance region appears afterV _m (turn over voltage), beyond which voltage goes down with increase of current. A possible mechanism is discussed in terms of dynamics of charged solitons and domain walls in one-dimensional molecular stacks of these types of crystals.     

ZnO陶瓷材料的负阻特性

介绍了ＺｎＯ陶瓷的负阻特性，主要研究了ＭｎＯ２掺杂和Ｎｉ２Ｏ３掺杂对ＺｎＯ陶瓷负阻特性的影响。