Myopia,amnesia, and consistent intertemporal choice

Social scientists often explain observed streams of behavior as the outcome of constrained choice at successive dates, with actors choosing among planned sequences of actions extending into the future. This paper presents four axioms for consistent intertemporal choice in such models. Within this framework, myopia and amnesia are defined to be choice processes in which future feasible actions and past decisions, respectively, play no role in current choice. Each of these modeling strategies is argued to have some plausibility on the basis of bounded rationality considerations. It is shown that an anticipatory process reduces to a behaviorally equivalent myopic process if and only if binary choices are lexically organized. Amnesia, or the absence of endogenous preference formation, is characterized by the condition that binary choices be ‘ahistorical’. The paper closes with some remarks on the methodological role of the consistency axioms, and the problems posed by inconsistent choice processes.     

Dual role of price and myopia in a marketing channel

In this paper we study a dynamic two-player channel where the manufacturer controls the wholesale price and the investment in quality and the retailer chooses the retail price. We consider that the retail price affects both the demand and the perceived quality of the brand and that its variations contribute to the building of an internal reference price. One of the model’s distinctive features is that it accounts for the two meanings of price, i.e., its classical objective measure of the cost of acquiring a particular quantity of the product, and its subjective roles as an assessment of the quality of the product and an evaluation of gains or losses (deal vs. sacrifice) resulting from buying a “cheap” or an “expensive” product. This dual computation is done with respect to the internal reference price.     

角膜塑形镜与框架镜控制近视进展的Meta分析

目的 评价角膜塑形镜控制儿童近视进展的有效性及安全性。方法 计算机检索Pubmed、OVID、The Cocharane Library、EMbase、CBM、万方、CNKI等数据库,全面收集角膜塑形镜控制儿童近视的随机对照试验（RCT）及非随机的前瞻性同期对照临床试验,检索时间为1990年1月至2014年5月,并追溯纳入文献的参考文献。由2位研究者按照纳入与排除标准独立筛选文献、提取资料及评价文献质量,采用RevMan5.2软件进行Meta分析。结果 共纳入5篇文献,323 例患者。Meta分析结果显示,角膜塑形镜在控制眼轴增长方面明显优于框架镜,两组差异有统计学意义[ MD= -0.25,95%CI（-0.32,-0.19）,P＜0.00001 ]。角膜塑形镜组玻璃体腔深度延长少于框架镜组（P＜0.001）。角膜塑形镜组出现6例角膜荧光素染色阳性,1例角膜浸润,1例结膜充血。结论 角膜塑形镜能明显控制低度近视儿童的眼轴增长,角膜荧光染色阳性是主要并发症。     

Optical quality in a myopic population of human eyes

An aberrometer was used to measure the monochromatic aberration of 219 eyes in a population of 113 myopic subjects. The Zernike expansion was used to describe the wavefront aberration of the human eyes. From the distribution of Zernike coefficients, the means of almost all Zernike coefficients are approximately zero, and the mean absolute values of Zernike coefficients convey the level of aberration for our study population. Based on the distribution of Zernike coefficients, the averaged optical quality was computed in different methods. The mean MTF and PSF of individual eyes represent the optical quality for a typical myopic eye. Through the calculation of the visual benefits expected from correcting Zernike modes, a large expected visual benefit can be achieved across all spatial frequencies after correcting 5 Zernike modes. Furthermore, the larger improvement of optical quality can be achieved with correcting more Zernike modes at a higher spatial frequency.     

汉族儿童近视眼与角膜波阵面像差的相关性研究

目的 观察儿童眼轴长度（AXL）、角膜曲率（K）、前房深度（ACD）等屈光参数以及角膜高阶像差的变化特点。方法 收集64 例（64 眼）汉族近视儿童的资料（6～12 岁），以右眼为研究对象，采用散瞳验光测定屈光不正度数并计算等效球镜度数（SE）、角膜地形图测定并计算K 值、A 超测定AXL和ACD。角膜像差通过角膜地形图数据转换成Zernike多项式获得。所有病例均跟踪随访观察1 年，对比1 年前后的各参数的变化，分析各屈光参数与高阶像差间的相关性。结果 患儿1年后出现显著近视化方向漂移，以眼轴延长为主要特征，ACD 亦有显著加深，差异均有统计学意义（均P＜0.01）。角膜高阶像差则无显著变化（P＞0.05）。入选时角膜Zernike 3阶总像差与SE 显著相关（P＜0.01），Z（4,0）球差与SE 也显著相关（P＜0.05）。1年后，角膜像差与SE 及各屈光参数无显著相关性（均P ＞0.05）。结论 儿童在青少期近视化进展显著，且以眼轴延长为主要特征，而角膜高阶像差与近视化发展的相关性尚有待进一步研究。