Peutz-Jeghers syndrome: clinicopathology and molecular alterations

Peutz-Jeghers syndrome (PJS, OMIM 175200) is an unusual inherited intestinal polyposis syndrome associated with distinct peri-oral blue/black freckling [1–9]. Variable penetrance and clinical heterogeneity make it difficult to determine the exact frequency of PJS [4]. PJS is a cancer predisposition syndrome. Affected individuals are at high risk for intestinal and extra-intestinal cancers. In 1997, linkage studies mapped PJS to chromosome 19p [10, 11], and subsequently a serine/threonine kinase gene defect (LKB1) was noted in a majority of PJS cases [12, 13]. A phenotypically similar syndrome has been produced in an LKB1 mouse knockout model [14–18]. Several PJS kindred without LKB1 mutations have been described, suggesting other PJS loci [19–22]. The management of PJS is complex and evolving. New endoscopic technologies may improve management of intestinal polyposis. Identification of specific genetic mutations and their targets will more accurately assess the clinical course, and help gage the magnitude of cancer risk for affected individuals. Received 20 February 2006; received after revision 5 May 2006; accepted 15 June 2006     

Nodal signals pattern vertebrate embryos

Vertebrate embryonic patterning requires several conserved inductive signals–including Nodal, Bmp, Wnt and Fgf signals. Nodal, which is a member of the transforming growth factor β (TGFβ) superfamily, activates a signal transduction pathway that is similar to that of other TGFβ members. Nodal genes, which have been identified in numerous vertebrate species, are expressed in specific cell types and tissues during embryonic development. Nodal signal transduction has been shown to play a pivotal role in inducing and patterning mesoderm and endoderm, and in regulating neurogenesis and left-right axis asymmetry. Antagonists, which act at different steps in the Nodal signal transduction pathway, have been shown to tightly modulate the inductive activity of Nodal. Received 20 October 2005; received after revision 15 November 2005; accepted 25 November 2005     

未知噪声统计的交错估计GPS导航定位算法

将未知噪声统计量的估计与信号状态估计交替进行的算法引入 Ｇ Ｐ Ｓ定位,计算机模拟结果表明效果很好。     

植物标签技术

传统的正向遗传学主要用于克隆表型或功能已确定的基因。转座子标签突变体可用随机标签法从带有活性转座子的自交后代中筛选得到,或用定向标签法从杂交一代中筛选得到,即用目的基因的隐性突变统合体与具高度活性转座号的统合体杂交,极大多数的FI个体为正常表型,但其中会有极少量的表现隐性性状的转庄子插入突变体。正向基因标签和克隆法在利用异源和低拷贝数品系时尤其有用。采用反向fCR或热不对称交替PCR（TAIL－PCR）且很容易从单拷贝或低拷贝数品系中获得插入于两侧的基因组序列。TAIL－PCR由三轮连续的半巢式PCR组成,所…     

一种基于导弹地面试验台的对心调节机构设计与研究

针对导弹地面试验台中需要很多对心安装工作,如迷宫内外套对心安装等,存在安装过程复杂,调整困难,安装时间长,定位精度较差等问题。以迷宫内外套对心安装为例,通过非标结构选型和加工,设计了一套对心调节机构,通过现场安装对比,得出新型对心调节机构具有定位精度高、操作简单方便、大大节约工作时长、调节迅速且简便等优点。该新型对心调节机构,对导弹地面试验台其他需要对心调整的工作,同样具有简单、高效、节约成本的作用,它的设计与研究有很高的工程实践意义。     

不同环境温度下的织物芯输送带压陷滚动阻力仿真研究

随着带式输送机绿色节能要求的提高,如何有效减小压陷滚动阻力成为重要课题。为研究环境温度对带式输送机压陷滚动阻力的影响规律,并克服实际工程数据检测难这一困难,提出了一种围绕环境温度的有限元仿真方法。以织物芯带式输送机为研究对象,通过SolidWorks建立三维模型,之后利用ANSYS Workbench有限元分析软件开展在不同环境温度下的压陷滚动阻力仿真研究,其中使用Mooney-Rivlin的两参数模型定义输送带覆盖层材料。结果表明,环境温度的升高使得压陷滚动阻力逐渐减小。研究结果为带式输送机绿色节能提供了依据。     

LBHF型电液执行机构的通电锁位功能改造

本文从分析锦州石化分公司三催化车间一起闪电事故入手,分析了采用SA-4B型放大器的LBHF型电液执行机构在事故发生时不锁位的原因,并对其进行了改造,使其成为真正的事故安全型电液执行机构。     

汽车电子机械制动器的效能分析

为了分析电子机械制动器（electmmechanical bloking,简称EMB）的制动效能,建立了电子机械制动器的数学模型和在水平路面上汽车制动时整车动力学模型,运用MATLAB／SIMULINK仿真软件对电子机械制动器和液压制动器（hydmulic braking简称HB）的制动性能进行了比较．结果表明：电子机械制动器的制动效能明显优于传统的液压制动器,为电子机械制动器工程开发提供了理论依据.