用蒙特卡罗方法确定81-02型198Au短程治疗源剂量计算参数

针对81-02型¹⁹⁸Au短程治疗源的临床应用，用蒙特卡罗方法计算了在一半径为30cm的理论球体模型中，AAPMTG43U1所推荐剂量计算参数的数值，包括剂量率常数、径向剂量函数和各向异性函数。所得单个81-02型¹⁹⁸Au短程治疗源的剂量率常数为1.113 cGy·h^-1·U^-1，与Dauffy等的理论计算值和TLD实测值分别相差0.18%和1.62％。在源中垂轴0.1～10.0cm距离范围内计算径向剂量函数的数值，在角度0°～90°（10°间隔）、距离0.5～9.0cm（1cm间隔）范围内计算各向异性函数的数值，最后对径向剂量函数和各向异性函数进行拟合，得到实用性较强的经验公式。     

基于颜色描述的快速视频去雾算法

雾霾天气下拍摄的图像,由于大气中混浊悬浮物对光的吸收和散射的影响,导致"透光"强度减弱,图像能见度严重降低,许多特征被覆盖或模糊,限制和影响了可见光视觉系统工作效用的发挥.研究针对低能见度天气下,可见光视觉系统工作受限的现实,从雾天图像退化模型出发,通过发掘颜色分布与透射率两者之间的约束关系构建透射率求解方程.之后,通...     

大型冶金成套设备合作制造模式的现状分析与改进方案

根据我国大型钢铁企业"十五"、"十一五"期间从国外引进了大批先进的冶金技术和成套设备,其中国内有加工能力的重要设备均采用"联合设计、合作制造"的引进方式。结合武钢最近十几年来引进设备的实践经验,对传统合作制造模式在实际操作过程中出现的各种利弊通过实例进行详细分析研究,分析研究的结果为弊大于利,并研究提出了一种改进型的合作制造模式,经过试用效果良好,值得在冶金及其它行业企业的设备采购系统推广应用。     

系统动力学在累积环境影响评价中的应用研究

文章分析了利用系统动力学 (SD)方法进行累积影响评价的能力 .实例研究表明 ,SD方法能较好地反映环境影响的动态变化过程 ,在空间累积效应的评价方面也有一定作用 ,是进行累积影响评价的有效方法     

Contourlet变换在图像检索中的应用

利用 Contourlet 变换良好的稀疏特性及其能准确地捕获图像中边缘信息的特性,分析了纹理图像Contourlet系数的统计特征,提出了一种滤波算法。该算法根据纹理图像Contourlet系数分布的特点,采用高斯模型对其进行精确拟合提取纹理特征,针对各子带数据的离散程度进行加权处理,为分类能力强的特征量赋予较大的权值,并加入在低频子带上提取的灰度—平滑共生矩阵统计量,来形成最终的特征向量,以两幅图像不同特征向量间的加权欧氏距离作为图像的相似度进行检索。仿真实验结果表明,该方法在检索效果上有一定的优越性。     

ADS熔盐散裂靶中子学性能研究

与传统加速器驱动次临界系统（ADS）采用金属靶作为散裂中子靶的设计不同,加速器驱动次临界熔盐堆（AD-MSRs）采用靶堆一体的设计,直接使用燃料熔盐作为散裂中子靶。由于熔盐靶的中子学性能直接影响AD MSRs的能量放大系数、核废物的嬗变和核燃料增殖的效率,所以本研究基于MCNPX程序,详细计算了高能质子轰击氟盐和氯盐两种熔盐靶产生的散裂中子产额、散裂中子能谱、能量沉积分布以及散裂产物等中子学性能,并与液态Pb和铅铋共熔体（LBE）两种液态金属靶进行了对比。计算结果表明,熔盐靶在散裂中子产额上与液态金属靶有一定的差距,但熔盐靶内能量沉积分布的梯度较小,更有利于靶区的热量导出。与液态Pb和LBE靶相比,熔盐靶的散裂产物中包含更多的气体以及高质量数的α发射体核素。     

基于分布式组件动态集成的网络GIS设计模式及其实现*

摘要：提出了一种基于分布式组件动态集成方法的网络GIS开发模型。该模型允许用户定制扩展功能组件,提供扩展组件与原有系统实时、动态、无缝集成机制,并可在一个平台上提供实现C/S及B/S两种网络GIS工作模式,并提供单机模式的后台数据管理系统,满足了中小型应用系统对网络GIS平台功能小而全的需求。阐述了该开发模型的概念设计、架构设计及关键技术,并开发实现了一个原型系统FreeXGIS,验证了该模型的可行性。     

TV图像插值的双方向扩散改进算法

提出了一种双方向扩散图像插值方法,有效地减小了插值图像的边缘宽度,从而获得清晰而光滑的图像边缘.这种双方向扩散在图像边缘斜坡较亮一侧进行前向扩散,而在边缘斜坡较暗一侧进行后向扩散.同时,它能根据图像边缘的特征自适应地调整前向、后向扩散强度,从而避免了在插值的图像中产生虚的纹理或边缘.数值实验结果显示,该方法既能很好地减小插值图像的边缘宽度,又不会产生其他人工虚像.     

Secreted HSP90α-LRP1 Signaling Promotes Tumor Metastasis and Chemoresistance in Pancreatic Cancer

The extracellular heat shock protein 90α (eHSP90α) has been reported to promote cancer cell motility. However, whether pancreatic cancer (PC) cells expressed membrane-bound or secreted HSP90α, as well as its underlying mechanism for PC progression, were still unclear. Our study demonstrated that the amounts of secreted HSP90α proteins were discrepant in multiple PC cells. In addition, highly invasive Capan-2 cells have a higher level of secreted HSP90α compared with those of less invasive PL45 cells. The conditioned medium of Capan-2 cells or recombinant HSP90α treatment stimulated the migration and invasion of PC cells, which could be prevented with a neutralizing anti-HSP90α antibody. Furthermore, secreted HSP90α promoted elements of epithelial–mesenchymal transition in PL45 cells, including increases in vimentin and Snail expressions, decreases in E-cadherin expression, and changes in cell shape towards a mesenchymal phenotype, but these phenomena were reversed by the anti-HSP90α antibody in Capan-2 cells. In addition, high levels of low-density lipoprotein receptor-related protein 1 (LRP1) were associated with worsened patient survival in pancreatic adenocarcinoma. We demonstrated LRP1 as a receptor of eHSP90α for its stimulatory role in metastasis, by activating the AKT pathway. In addition, silencing LRP1 enhanced the chemosensitivity to gemcitabine and doxorubicin in Capan-2 cells. Therefore, our study indicated that blocking secreted HSP90α underlies an aspect of metastasis and chemoresistance in PC.     

Genome-Wide Association Study Identifies a Rice Panicle Blast Resistance Gene,Pb2, Encoding NLR Protein

Rice blast is one of the main diseases in rice and can occur in different rice growth stages. Due to the complicated procedure of panicle blast identification and instability of panicle blast infection influenced by the environment, most cloned rice resistance genes are associated with leaf blast. In this study, a rice panicle blast resistance gene, Pb2, was identified by genome-wide association mapping based on the panicle blast resistance phenotypes of 230 Rice Diversity Panel 1 (RDP1) accessions with 700,000 single-nucleotide polymorphism (SNP) markers. A genome-wide association study identified 18 panicle blast resistance loci (PBRL) within two years, including 9 reported loci and 2 repeated loci (PBRL2 and PBRL13, PBRL10 and PBRL18). Among them, the repeated locus (PBRL10 and PBRL18) was located in chromosome 11. By haplotype and expression analysis, one of the Nucleotide-binding domain and Leucine-rich Repeat (NLR) Pb2 genes was highly conserved in multiple resistant rice cultivars, and its expression was significantly upregulated after rice blast infection. Pb2 encodes a typical NBS-LRR protein with NB-ARC domain and LRR domain. Compared with wild type plants, the transgenic rice of Pb2 showed enhanced resistance to panicle and leaf blast with reduced lesion number. Subcellular localization of Pb2 showed that it is located on plasma membrane, and GUS tissue-staining observation found that Pb2 is highly expressed in grains, leaf tips and stem nodes. The Pb2 transgenic plants showed no difference in agronomic traits with wild type plants. It indicated that Pb2 could be useful for breeding of rice blast resistance.