Analysis and computation of ESI coefficient of planar waveguide based on field matching

首次采用了场的最小二乘方 (LSE)和最小均方误差 (LMS)判据寻找平板波导的等效阶跃折射率 (ESI)模型 ,并通过它预测了平板波导的传输特性。计算结果表明 ,原始波导与等效波导场分布在具有最大近似性的基础上 ,ESI模型可以在一定范围内有效的预测平板波导的传输特性。归一化频率与第一个高阶模的截止频率之比在小于 0 7的情况下 ,用上述两种判据找到的ESI模型预测传输常数相对误差小于 0 0 1 % ,预测归一化传输常数的相对误差小于 1 0 %。A method to find Effective Step-Index(ESI) model based on field matching criter ia of least-square-error(LSE) and least-mean-square(LMS) error is put forward, and the propagation quality from ESI coefficients is predicted. When the ESI model a n d the original waveguide have the best approximated field distribution, the prop agation quality of planar waveguide efficiently can be predicted based on ESI mo del in specific range. When the ratio between normalized frequency and cut-off fre quency of the first higher model is lower than 0.7, the relative error of predic t ing propagation constant from the ESI model is less than 0.01%, and the relative error of predictiong normalized propagation constant is less than 10%

降钙素受体基因多态性与老年男性骨密度关系

[目的]探讨降钙素受体基因（CTR）C1377T基因多态性与老年男性人群骨密度相互关系.[方法]选取年龄≥65岁广州地区汉族男性个体247例,采用双能X线吸收法（DEXA）测定其全身、腰椎2～4（L2～4）、股骨颈（Neck）、粗隆间（Inter）、Ward＇三角和大转子（Troch）区等部位的骨密度（BMD）值,并采用聚合酶链反应限制性片段长度多态性（PCR-RFLP）技术检测外周血白细胞基因组降钙素受体基因多态性.[结果]247例受试对象中,CTR基因型分别为CC型205例（83.0%）,CT型39例（15.8%）,TT型3例（1.2%）;基因频率CC型为90.9%,TT型为9.1%,基因型分布符合Hardy-weinberg定律.分析其基因型与骨密度的关系显示,含有酶切位点的个体（CT＋TT）除在腰椎侧位（L2～L4）及Ward＇三角（Ward＇s）的骨密度比不含酶切位点的基因型的骨密度值有显著性升高外（P＜0.05）,其他部位骨密度值之间的差异无统计学意义.[结论]降钙素基因C1377T基因多态性尚不能作为预测汉族老年男性发生骨质疏松危险性的遗传标志

Post-trauma Mental Health Problem among 8~14 Year Old Children and Its Risk Factors One Year after Sichuan Earthquake in Mianyang

目的:探讨BDNF Val66Met基因多态性与温暖的教养方式对青少年抑郁水平的影响。方法:采用爱荷华青年和家庭项目(Iowa Youth and Families Project)中教养问卷的温暖维度与儿童抑郁自评量表(Children’s Depression Inventory,CDI)分别对838名青少年抑郁症状与父母的教养方式进行测量,在确定被试BDNF Val66Met基因型后,用多重线性回归对测得数据进行分析。结果:温暖的家庭教养方式与青少年抑郁症状负相关;BDNF Val66Met多态性与青少年抑郁症状无显著相关;BDNF Val66Met多态性与温暖的家庭教养方式的交互作用显..

Post-trauma Mental Health Problem among 8～14 Year Old Children and Its Risk Factors One Year after Sichuan Earthquake in Mianyang

目的：了解震后1年北川小学生创伤症状的严重程度及风险因素。方法：在汶川地震1年后,整群抽样北川地区两所小学的715名3-5年级学生。使用自编基本情况问卷和儿童用创伤症状量表简版测查。结果：震后1年小学生的焦虑症状最为突出,其次是抑郁、创伤后应激障碍和分离,愤怒症状最弱。震前创伤、丧亲和当时感到强烈的害怕/无助/恐惧能显著预测创伤症状的各个维度;受伤和目睹死亡能预测PTSD症状和分离症状;男生的焦虑症状更严重。结论：震后1年灾区小学生心理健康状况仍然不容乐观,应当继续坚持心理辅导和干预,并特别关注有震前创伤、创伤暴露水平高（丧亲、受伤、目睹死亡）、和震时情绪反应强烈的学生

Application and Improvement of Finite-difference Time-domain Algorithm in the Analyses of Optical Waveguide

对时域有限差分算法在弱导光纤中应用时吸收边界条件的设置和计算结果的误差进行了讨论 ,并提出改善计算精度的方法。文中给出用这种方法计算普通光纤传输特性的结果In this paper,we discuss the application of CFDTD (Cylindrical Finite Difference Time Domain)algorithm in the analyses of weak guide optical fiber.Especially,the setting of the absorbing boundary condition and the error of the result are discussed.We present a way to improve the accuracy of the algorithm.Finally,the propagation characters of optical fiber are given in the paper

新型光纤的技术发展及应用

文章介绍了国际上最新的通信光纤的技术发展情况,包括新型多模光纤、单模光纤的制造技术及其应用,还详细地介绍了国内外最新类型的特种光纤及其发展、应用。此外,对我国光通信的技术现状、发展和趋势也进行了一定程度的阐述

Technology of Filters Based on Fiber Bragg Gratings

介绍了国际上最新的基于光纤Bragg光栅的光纤滤波技术发展情况,详细阐述了分布反馈式光纤Bragg光栅滤波器、多波长选择光纤Bragg光栅滤波器、应用光纤Bragg光栅的Michelson干涉型（MI）滤波器以及光纤Bragg光栅滤波耦合器的理论难点、基本原理及其应用。The paper introduces the latest technical development of band-pass filters based on fiber Bragg gratings.The major theoretical principle,as well as application of Distributed feed back FBG filters, multewavelength selectieve FBG filters, Michelson interferometer band-pass filters and in-coupler Bragg grating filters are elaborated in details

基于光纤Bragg光栅的滤波技术

介绍了国际上最新的基于光纤Bragg光栅的光纤滤波技术的发展情况,详细阐述了分布反馈式光纤Bragg光栅滤波器、多波长选择光纤Bragg光栅滤波器、应用光纤Bragg光栅的Michelson干涉型(MI)滤波器以及光纤Bragg光栅滤波耦合器的理论难点、基本原理及其应用

Technical Development and Application of Novel Optical Fiber

介绍了国际上最新的通信光纤技术发展情况 ,包括新型多模光纤、单模光纤的制造技术及其应用。文章还详细地介绍了国内外最新类型的特种光纤及其发展、应用。此外 ,对我国光通信的技术现状、发展和趋势也作了一定程度的阐述The paper introduces the latest technical development of communication fiber, including the manufacturing technology and application of novel multimode optical fiber and single mode optical fiber. The development and application of the latest special optical fiber are also presented in details, moreover, the domestic present situation and developing trend of fiberoptic communication are described to certain degree